Holistic Watershed Management for Existing and Future Land
Use Development Activities: Opportunities for Action for Local
Decision Makers: PHASE 2 - FDC APPLICATION MODELING
(FDC2A PROJECT)
SUPPORT FOR SOUTHEAST NEW ENGLAND PROGRAM (SNEP)
COMMUNICATIONS STRATEGY AND TECHNICAL ASSISTANCE
DRAFT Project Report
September 15,2022
Prepared for:
U.S. EPA Region 1
Prepared by:
Paradigm Environmental Great Lakes Environmental Center
PARADIGM
ENVIRONMENTAL
GleC
Blanket Purchase Agreement: BPA-68HE0118A0001-0003
Requisition Number: PR-R1-20-00322
Order: 68HE0121F0052
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FDC 2A Project
Draft Project Report
EXECUTIVE SUMMARY
This report presents a quantitative analysis of Flow Duration Curves (FDCs) and other associated metrics
for understanding the impact of land use decision-making on freshwater flow regimes and ecosystem health.
These analyses are based on long-term continuous hydrologic models developed under Phase 1 of this project
for the Taunton River Basin in eastern Massachusetts using the Loading Simulation Program in C++ (LSPC)
and EPA's stormwater best management practices optimization (Opti-Tool) models. The goal of this report
(Phase 2A) is to conceptualize, evaluate, and communicate the benefits of next-generation conservation-
focused development and stormwater management practices.
The project goals are demonstrated by modeling and evaluating a wide range of scenarios from individual
stormwater control measures (SCMs), to conservation-focused conceptual new and redevelopment sites, to
a small urbanized watershed using both historic and future projections of land use and climate. Results
presented in this report indicate that individual conservation-focused SCMs, when sized to maintain
predevelopment hydrologic conditions, can achieve 95% and 90% reductions in annual average Total
Nitrogen (TN) and Total Phosphorous (TP) load, respectively. These High control SCMs outperform
conventional (MS4) control SCMs by 8% for TN and by 13% for TP. When individual High control SCMs
are combined within a new or redevelopment site, they can be configured as a system to achieve goals such
as maintaining resilient, predevelopment hydrology with little to no net increase in nutrient loads. This was
demonstrated for a high-density residential site, a high-density commercial site, and a low-density residential
site in this report.
Average annual pollutant reductions (%) for individual conventional (MS4) and conservation (High) control SCMs
Metric
Flow Volume
TSS
TN
TP
Zn
MS4
High
MS4
High
MS4
High
MS4
High
MS4
High
Minimum3
17%
35%
95%
99%
79%
90%
65%
80%
87%
94%
Average
45%
66%
98%
99%
87%
95%
77%
90%
93%
98%
Maximum15
89%
91%
99%
100%
97%
99%
98%
99%
99%
100%
a Hydrologic Soil Group (HSG) D;b HSG A
One of the key comparisons made in this report is the reduction in pollutants for a watershed with
conventional SCMs based on current MassDEP and MS4 standards and a watershed with conservation-
focused SCMs. This was evaluated using the Upper Hodges Brook subwatershed, a small urbanized
subwatershed within the Taunton River Basin, which was selected as a pilot for this study. This comparison
is visualized in the figure below. For example, with Conservation Development (High control SCMs and
regulations that require treating flow from 80% of impervious cover [1 /8th of an acre threshold for MS4]) the
watershed's TP load is reduced by 48% compared to 14% for the Business-as-Usual scenario (MS4 control
SCMs and 30% of IC area treated [1-acre threshold for MS4]). FDCs for these comparisons are presented in
the report and illustrate impacts on the flow regime of Upper Hodges Brook. Across the FDCs, the amount
of flow above or below the predeveloped condition can be summarized as ecosurpluses and ecodeficits.
Compared to the Business-as-Usual scenario, the Conservation Development scenario reduced ecosurpluses
and essentially eliminated ecodeficits.
The SCMs evaluated in this report represent structural controls for treating runoff from impervious surfaces.
While the performance of Conservation Development SCMs at the SCM scale and site scale represents a
marked improvement over stormwater management in conventional development, at the watershed scale
their impact depends on the amount of impervious cover and the percentage of that IC which is being treated.
This highlights the fact that stormwater management requires multifaceted approaches including structural
controls, as well as source control (e.g., fertilizer reduction, pet waste collection) from pervious areas to be
most effective. Evaluating the impact of structural and source controls in combination at the watershed level
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in future work would provide valuable insights for next-generation conservation development and
stormwater management.
Business-as-Usual
Conservation Development
Hypothetical Maximum
CO
*
03
Pervious H) Impervious (^Treated Impervious
.
O
40 —
20
500
Ecosurplus Ecodeficit
¦ Unmanned
Ecosurplus Ecodeficit
• Unmanaged
Ecosurplus Ecodeficit
¦ Unmanned
Summary information for Business-as-Usual, Conservation development, and hypothetical maximum watershed
management scenarios and their impact on Total Phosphorous and flow regime in the Upper Hodges
Brook watershed.
n
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Table of Contents
Executive Summary i
1. Introduction 8
2. GIS Data Review for THE Taunton River Watershed 10
2.1. Baseline Land Use Land Cover Data 10
2.2. Future Land Cover Data 12
2.3. Municipalities 13
2.4. Buildings 14
2.5. Baseline HRUs Layer 15
3. Development of Future HRU Layer for Taunton River Watershed 21
3.1. Land Cover Change Between 2010 and 2060 NELF Dataset 22
3.2. Mapping Between Opti-Tool and NELF Land Use Classification 22
3.3. Percent Imperviousness for Developed Land Use Classification 25
3.4. Developed Land Use Distribution by Municipality in Taunton River Watershed 26
3.5. Future HRU Layer for the Taunton River Watershed 29
4. Selection of Future Climate Models 34
5. Comparison of Existing and Future (IC and Climate) Conditions in THE Taunton River Watershed 35
5.1. Change in Impervious Cover by 2060 in Taunton River Watershed 35
5.2. Change in Hydrology and Water Quality by 2060 in Taunton River Watershed 37
5.3. Summary of Changes from Future IC and Climate 42
6. Impacts of Future Land Use and Climate on the Upper hodges Brook Subwatershed 45
7. Site Scale Modeling Analyses 53
7.1. Site Scale Modeling Scenarios 53
7.2. Site Scale Opti-Tool Setup 54
7.3. Site Scale Modeling Results 65
8. HRU Scale Modeling Analyses 74
8.1. HRU Scale Modeling Scenarios 74
MassDEP and MS4 Control 74
High Control 75
8.2. HRU Scale Opti-Tool Setup 76
8.3. HRU Scale Modeling Results 77
9. Watershed Scale Modeling Analyses 86
9.1. Watershed Scale Next-Generation SCM Modeling Scenarios 86
9.2. Watershed Scale Opti-Tool Setup 86
9.3. Watershed Scale Modeling Results 93
10. Conclusions and recommendations 98
11. References 99
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Figures
Figure 2-1. A map showing 2016 land use - land cover for the Taunton River watershed 11
Figure 2-2. A historical land use trend for the year 2010 (left) and projected future land use trend for the year
2060 (right) for the Taunton River watershed 12
Figure 2-3. A map showing the municipal boundaries in the Taunton River watershed 13
Figure 2-4. A map showing the building footprints in the Taunton River watershed 14
Figure 2-5. Baseline HRUs spatial overlay process (from top to bottom: land use - land cover, soil, and slope
layers) 16
Figure 2-6. A map showing the 2016 baseline HRU raster layer for the Taunton River watershed 20
Figure 3-1. Mapped future HRU spatial overlay process (from top to bottom: NELF 2060 land cover,
baseline HRUs, municipalities, and final future HRU layer) 30
Figure 3-2. A map showing the 2060 future HRU raster layer for the Taunton River watershed 32
Figure 3-3. A map showing the comparison between the 30-m resolution 2060 future NELF layer (left) and
1-m resolution 2060 future HRU layer (right) for the Upper Hodges Brook sub-watershed 33
Figure 4-1. Percent change in annual average precipitation and temperature from baseline conditions for the
FDC Phase 1 selected models presented in Table 4-1 34
Figure 5-1. Comparison of changes in hydrology (runoff, groundwater recharge GW, and evapotranspiration
ET) and water quality parameters (total nitrogen TN and total phosphorous TP) between the baseline and
future land use/climate conditions across the entire Taunton River watershed 42
Figure 6-1. Flow duration curves for the Upper Hodges Brook for predevelopment, baseline (2016 existing
conditions), and future land use/land cover (FLULC) with varying amounts of IC disconnection (existing
condition, fully connected (EIA=TIA), and fully disconnected (EIA=0)). All scenarios use historic climate
data 47
Figure 6-2. Water balance (pie charts) and FDC comparisons for existing baseline conditions and future land
use with the historic climate scenario for the Upper Hodges Brook subwatershed 48
Figure 6-3. Water balance (pie charts) and FDC comparisons for existing baseline conditions and future land
use with the dry future climate scenario for the Upper Hodges Brook subwatershed 49
Figure 6-4. Water balance (pie charts) and FDC comparisons for existing baseline conditions and future land
use with the median future climate scenario for the Upper Hodges Brook subwatershed 50
Figure 6-5. Water balance (pie charts) and FDC comparisons for existing baseline conditions and future land
use with the wet future climate scenario for the Upper Hodges Brook subwatershed 51
Figure 6-6. Comparison of changes in hydrology (runoff, groundwater recharge GW, and evapotranspiration
ET) and water quality parameters (total nitrogen TN and total phosphorous TP) between the baseline and
future land use/climate conditions for the Upper Hodges Brook subwatershed 52
Figure 7-1. Opti-Tool watershed sketch for Scenario 1.3 with conceptual SCM diagrams 55
Figure 7-2. Opti-Tool watershed sketch for Scenario 1.4 with conceptual SCM diagrams 56
Figure 7-3. Opti-Tool watershed sketch for Scenario 2.3 with conceptual SCM diagrams 57
Figure 7-4. Opti-Tool watershed sketch for Scenario 2.4 with conceptual SCM diagrams 58
Figure 7-5. Runoff duration curve for CD1.3 with historic and future climate 66
Figure 7-6. Runoff duration curve for CD1.4 with historic and future climate 66
Figure 7-7. Runoff duration curve for CD2.3 with historic and future climate 67
Figure 7-8. Runoff duration curve for CD2.4 with historic and future climate 67
Figure 7-9. Runoff duration curve for CD3.3 with historic and future climate 68
Figure 7-10. Runoff duration curve for CD3.4 with historic and future climate 68
Figure 7-11. Hyetograph (top) and hydrograph (bottom) for a 10yr-24hr storm event for CD2.4 illustrating
peak runoff capture of the GI and CD practices that is similar to the predeveloped condition 69
Figure 7-12. Hyetograph (top) and hydrograph (bottom) for a 10yr-24hr storm event for CD3.4 illustrating
peak runoff capture of the GI and CD practices that is similar to the predeveloped condition 70
Figure 7-13. Annualized TP, TSS, and Runoff load and removal cost for High Density Residential (HSG-C)
conceptual design for conventional development practices and GI and conservation design practices with
historic climate 71
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Figure 7-14. Annualized TP, TSS, and Runoff load and removal cost for High Density Commercial (HSG-
A) conceptual design for conventional development practices and GI and conservation design practices with
historic climate 72
Figure 7-15. Annualized TP, TSS, and Runoff load and removal cost for Low Density Residential (HSG-C)
conceptual design for conventional development practices and GI and conservation design practices with
historic climate 73
Figure 8-1. Runoff duration curve for MS4 control level infiltration basin on HSG C with an infiltration rate
of 0.17 in/hr 80
Figure 8-2. Runoff duration curve for High control level infiltration basin on HSG C with an infiltration rate
of 0.17 in/hr 80
Figure 8-3. Runoff duration curve for MS4 control level infiltration trench on HSG C with an infiltration
rate of 0.17 in/hr 81
Figure 8-4. Runoff duration curve for High control level infiltration trench on HSG C with an infiltration
rate of 0.17 in/hr 81
Figure 8-5. Runoff duration curve for High control level infiltration basin on HSG A with an infiltration rate
of 2.41 in/hr with historic and future climate 82
Figure 8-6. Runoff duration curve for High control level infiltration basin on HSG B with an infiltration rate
of 0.52 in/hr with historic and future climate 82
Figure 8-7. Runoff duration curve for High control level infiltration basin on HSG C with an infiltration rate
of 0.17 in/hr with historic and future climate 83
Figure 8-8. Runoff duration curve for High control level infiltration basin on HSG D with an infiltration rate
of 0.05 in/hr with future climate 83
Figure 8-9. Runoff duration curve for High control level infiltration trench on HSG A with an infiltration
rate of 2.41 in/hr with future climate 84
Figure 8-10. Runoff duration curve for High control level infiltration trench on HSG B with an infiltration
rate of 0.52 in/hr with future climate 84
Figure 8-11. Runoff duration curve for High control level infiltration trench on HSG C with an infiltration
rate of 0.17 in/hr with future climate 85
Figure 8-12 Runoff duration curve for High control level infiltration trench on HSG D with an infiltration
rate of 0.05 in/hr with future climate 85
Figure 9-1 Flow duration curve with MS4 control of 80% of the Upper Hodges Brook subwatershed's
impervious cover under historic LULC and climate conditions (Scenario 1) 95
Figure 9-2. Flow duration curve with High control of 80% of the Upper Hodges Brook subwatershed's
impervious cover under historic LULC and climate conditions (Scenario 7) 95
Figure 9-3. Flow duration curve with MS4 control of 80% of the Upper Hodges Brook subwatershed's
impervious cover under historic LULC and climate conditions (Scenario 6) 96
Figure 9-4 Flow duration curve with High control of 80% of the Upper Hodges Brook subwatershed's
impervious cover under future LULC and climate conditions (Scenario 12) 96
Figure 9-5. Comparison of ecosurpluses and deficits for each watershed scale scenario and percentage of IC
treated 97
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Tables
Table 2-1. Landscape GIS data 10
Table 2-2. Land use - land cover reclassification 17
Table 2-3. Soil - HSG reclassification 18
Table 2-4. Percent slope reclassification 18
Table 2-5. Summary of final HRU categories 18
Table 3-1. NELF recent trend 2010 and 2060 land cover comparison 22
Table 3-2. Reclassification Scheme for CCDC and NLCD Data for NELF Land Cover (Thompson et al.,
2017) 22
Table 3-3. Mapping table between NELF and Opti-Tool land use classification 25
Table 3-4. Summary of percent imperviousness for developed land use classification 26
Table 3-5. Summary of high-density development land use area distribution by municipality in the Taunton
River watershed 26
Table 3-6. Summary of low-density development land use area distribution by the municipality in the
Taunton River watershed 27
Table 3-7. Comparison ofHRU area distribution between theMassGIS 2016 baseline and NELF 2060 future
conditions in the Taunton River watershed 31
Table 4-1. FDC Phase 1 selected models from ensemble results for future climate projections (2079-2099)
34
Table 4-2. Summary of ecosurpluses and ecodeficits (million gallons per year) within the Upper Hodges
Brook watershed for RCP 4.5 and 8.5 scenarios 35
Table 5-1. Summary of increase in impervious cover by the municipality in the Taunton River watershed
35
Table 5-2. Summary of unit-acre-based annual average (Oct 2000 - Sep 2020) runoff volume, groundwater
(GW) recharge, evapotranspiration (ET), total nitrogen (TN) load, and total phosphorus (TP) load for the
modeled HRU types in the Wading River watershed (FDC Phase 1) 37
Table 5-3. Summary of unit-acre-based annual average (Oct 2079 - Sep 2099) runoff volume, groundwater
(GW) recharge, evapotranspiration (ET), total nitrogen (TN) load, and total phosphorus (TP) load for the
modeled HRU types in the Wading River watershed (Ecodeficit 8.5 Dry) 38
Table 5-4. Summary of unit-acre-based annual average (Oct 2079 - Sep 2099) runoff volume, groundwater
(GW) recharge, evapotranspiration (ET), total nitrogen (TN) load, and total phosphorus (TP) load for the
modeled HRU types in the Wading River watershed (Ecodeficit 8.5 Median) 39
Table 5-5. Summary of unit-acre-based annual average (Oct 2079 - Sep 2099) runoff volume, groundwater
(GW) recharge, evapotranspiration (ET), total nitrogen (TN) load, and total phosphorus (TP) load for the
modeled HRU types in the Wading River watershed (Ecodeficit 8.5 Wet) 40
Table 5-6. Summary of change in major land use area distribution between 2016 baseline and 2060 future
conditions in the Taunton River watershed 43
Table 5-7. Summary of changes between baseline land use and historic climate model results and the future
land use and climate scenarios for annual average runoff volume, groundwater (GW) recharge,
evapotranspiration (ET), total nitrogen (TN) load, and total phosphorus (TP) load by major land use in
Taunton River watershed 44
Table 6-1. Summary of changes in the land cover area between baseline land cover and the future land cover
in Upper Hodges Brook sub-watershed 45
Table 7-1. Conceptual design scenarios 53
Table 7-2. SCM drainage areas (acres) for the concept designs 1, 2, and 3 59
Table 7-3. SCM capacity (ft3) for the concept designs 1, 2, and 3 60
Table 7-4. SCM design specifications for conceptual design 1 61
Table 7-5. SCM design specifications for conceptual design 2 62
Table 7-6. SCM design specifications for conceptual design 3 63
Table 7-7. Summary of total cost and cost of unit-acre IC treated for each scenario at site-scale concept plans
65
Table 8-1. Impervious Cover HRU SCM Design Storage Volume (DSV) Sizing for MassDEP (2008) & MS4
level of Control (MS4 Control) 74
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Table 8-2. Impervious Cover HRU SCM Design Storage Volume (DSV) Sizing for Predevelopment Average
Annual Recharge and Nutrient Export Level of Control (High Control) 75
Table 8-3. SCM specifications for HRU level models 76
Table 8-4. Summary of cost of unit-acre IC treated for HRU level SCM scenarios 78
Table 8-5. Annual average percent reductions for HRU level SCM scenarios 79
Table 8-6. Change in annual average percent reduction for selected HRU-level SCM scenarios with a future
climate 79
Table 9-1. Table of watershed-scale modeling scenarios using HRU level SCMs 86
Table 9-2. SCM drainage areas (ac) for watershed scale scenarios by the percentage of IC treated 87
Table 9-3. SCM footprints (ft2) for watershed scale scenarios by the percentage of IC treated and LULC and
climate boundary conditions 89
Table 9-4. SCM specifications for watershed scale scenarios 92
Table 9-5. Summary of total cost and cost of unit-acre IC treated for each scenario at the watershed-scale93
Table 9-6. Watershed total annual average percent reductions for watershed level scenarios with 30%, 80%,
and 100% IC treated 94
Table 9-7. Impervious cover annual average percent reductions for watershed level scenarios with 30%, 80%,
and 100% IC treated 94
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1. INTRODUCTION
Stormwater management is a key component of minimizing the impact of development on freshwater
ecosystems. The health of these ecosystems is influenced by the characteristics of a long-term flow regime
(Walsh et al., 2016), however, stormwater management is largely focused on matching pre-development
peak flow for a small set of design storms. The purpose of this project has been to (1) demonstrate the use of
flow duration curves (FDCs) as a more holistic metric for stormwater management (Phase 1) and (2) envision
the next generation of stormwater management structures, regulations, and bylaws (Phase 2).
Land use decision-making, especially in terms of the extent and connectedness of impervious cover (IC), is
a driving factor behind changes to freshwater flow regimes and ecosystem health. FDCs provide a powerful
tool to illustrate the effect of land use decision-making at scales ranging from large basins to individual sites.
Through FDC application at the site scale, potential next-generation local regulatory options (i.e., municipal
bylaws/ordinances that address stormwater management and site development activities) can be
conceptualized and evaluated. This information can help to inform land use planning by local decision-
makers, particularly for new development and/or redevelopment (nD/rD). Quantifying hydrologic, water
quality, and other impacts, as well as the benefits of potential management solutions (in part by applying the
FDC and continuous modeling simulation approaches at the site scale), will facilitate municipal practitioner
appreciation of how nD/rD impacts water quality, flooding frequency and duration, channel stability,
ecohydrological function, and hydrogeomorphology. With increased appreciation for land use impacts at
multiple scales, the next generation of nD/rD practices for robust stormwater management, here termed
Conservation Development (CD) practices, can be envisioned.
As contemplated here, CD practices promote the conservation of site-scale ecology to help ensure the
preservation of pre-development-like hydrology, hydrogeology, pollutant export, and ecological diversity
and vitality. Such practices are anticipated to include, among others, a de-emphasis of impervious cover
(e.g., primarily access roads, driveways, parking lots, and rooftops), and increased reliance on low-impact
development (LID) practices that emphasize next-generation site design and green infrastructure (GI)
management practices (e.g., dispersed hydrologic controls and soil management practices), architecture
(e.g., green roofs, LID) and landscape architecture. Additionally, CD practices can emphasize the value of
permeable vegetated land cover including opportunities for local agriculture uses to increase the
sustainability of local food systems and the use of forest canopy and landscape architecture to promote
evapotranspiration for hydrologic benefits and to offset the "heat island effect" that results from excessive
IC.
A key component of the evaluation of CD practices is consideration of projected future land use and climate
conditions. Recent research from the New England Landscape Futures (NELF) project indicates that recent
land cover changes over the 1990-2010 period are based on the conversion of forests into low- and high-
density development, as well as some land conservation within core forests (Thompson et al., 2017). Over
time, the impact of these development trends, without additional management, will continue to reduce
evapotranspiration (ET) and carbon sequestration, as well as increase pollutant load carried by greater
volumes of stormwater runoff. The impact of future development on hydrologic regimes and ecosystem
conditions will be compounded by the effects of an uncertain and changing climate. Projections of future
climate in the Massachusetts Climate Change Report (MA EOEE, 2011) estimate that annual precipitation
in the state will increase 5-8% in 2035-2064 and 7-14% in the period 2070-2099, with increased precipitation
rates especially occurring during winter months (Hayhoe et al., 2006). Similar trends are expected for the
entire New England region.
This project is about envisioning a different future in watershed management. Phase 1 (Paradigm
Environmental and Great Lakes Environmental Center, 2021) demonstrated the utility of FDCs and
provided a foundation for Phase 2 to develop an understanding between FDCs and watershed development.
In Phase 2, practitioners were asked to compare and consider likely scenarios ranging from inaction (status
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quo policies) to actions that incorporate flooding risks, stream-channel stability, increased pollutant export
and reduced base flows. These insights were used in Phase 2 A (presented in this report) and Phase 2B
(presented in a companion report), which conceptualizes site-scale CD practices and next-generation by-
laws/ordinances. The Phase 2A work documented in this report uses FDCs and other metrics to
communicate the impacts of watershed management decision-making for a wide range of scenarios,
including future status quo development and stormwater management which are compared to CD practices
at the site- and watershed scales for historic and future climate conditions. By quantifying and
communicating these impacts, practitioners can have an increased appreciation of the impact of nD/rD on
the future of their watersheds and glean the future of a watershed managed for optimal sustainability and
resilience, compared to one that acquiesces, or continues to facilitate by inertia, the phenomenon of "urban
sprawl".
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2. GIS DATA REVIEW FOR THE TAUNTON RIVER WATERSHED
The Phase 2 methodology uses previously acquired data from MassGIS (Bureau of Geographic Information)
during Phase 1, as well as new sources of future land use - land cover data from the NELF project. The
subset of data used for Phase 2 is shown in Table 2-1.
Table 2-1. Landscape GIS data
Description
Dataset
Resolution
Source
Baseline Land Use-Land Cover
LULC_2016
polygon
2016
-
MassGIS
Future Land Cover
Recent_Trends_2010
raster
1990-2010
30m
NELF
Recent_T rends_2060
raster
2010-2060
30m
NELF
Municipalities
Towns
polygon
2020
-
MassGIS
Buildings
Structures
polygon
2019
-
MassGIS
Baseline HRUs
Baseline_HRUs_2016
raster
2016
lm
FDC Phase 1
2.1. Baseline Land Use Land Cover Data
MassGIS 2016 land use - land cover layer contains a combination of land cover mapping from 2016 aerial
imagery and land use derived from standardized assessor parcel information for Massachusetts. It contains
both land use and land cover information as separate attributes and can be accessed independently or in a
useful combination with one another. For example, it is possible to measure the portions of pervious and
impervious surfaces for a commercial parcel. Figure 2-1 shows the land use - land cover map for the Taunton
River watershed.
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Residential - Single Family
Mixed Use - Primarily Commercial
Developed Open Space
in
Forested Wetland
Residential - Multi-Family
Mixed Use - Other
| Deciduous Forest
SUS
Non-forested Wetland
Residential - Other
| Other Impervious
| Evergreen Forest
BB
Saltwater Wetland
Commercial
| Right-of-way
Grassland
V\feter
Industrial
Cultivated
Scrub/Shrub
SH
Unconsolidated Shore
RSI
Mixed Use - Primarily Residential
Pasture/Hay
Bare Land
M
Aquatic Bed
Figure 2-1. A map showing 2016 land use - land cover for the Taunton River watershed.
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2.2. Future Land Cover Data
NELF is a multi-institutional project with the overarching goal of building and evaluating scenarios that
show how land use choices could shape the landscape over the next 50 years. The NELF project envisions
potential trends and impacts of landscape change in New England based on community collaboration and
expert analysis (NELF, n.d.). Future land cover data representing historical and projected trends was
acquired from the NELF project data repository (available on request at:
https://databasin.org/groups/26ceb6c7ece64bQd9872ell8bae80d41/'). These datasets were created with a
cellular land-cover change model using satellite imagery from 1990-2010 (Thompson et al., 2017). The
historical data represents observed trends from 1990-2010; the statistical relationships of land cover change
rate and spatial patterns were then linearly projected to the year 2060 as a baseline business-as-usual scenario
(Figure 2-2). Major land cover changes over the 1990-2010 period include forest loss to low- and high-density
development, as well as new land conservation (Thompson et al., 2017). Over 50 years between 2010 and
2060, the largest changes in land use across all of New England (not just the Taunton River watershed) were
a 37% increase in developed areas and a 123% increase in conserved areas (Thompson et al., 2020). However,
the conserved area is concentrated in core forest areas in northern New England (e.g., Maine and Vermont),
while the more developed southern areas saw lower land conservation. At 30-m resolution, both of these
datasets are consistent with the National Land Cover Databases (NLCD), however, they are limited to land
cover projections of seven lumped categories and do not directly estimate the percent imperviousness within
the land cover category. Both the Recent Trends 2010 and 2060 datasets, as well as other NELF future
scenarios, can be explored on their web viewer.
Recent Trends 2010
A
value
| High Density Development
| Low Density Development
J Unprotected Fores
I Conserved Fotesl
J Agriculture
~\ Cther
Recent Trends 2060
A
Value
High Oensty Development
Hj Low Density Development
]' "B Unprotected Foms
Conserves Porta
[ ! Aflncuitixe
[ 1 bftcf
Vtoter
Figure 2-2. A historical land use trend for the year 2010 (left) and projected future land use trend for the year 2060
(right) for the Taunton River watershed.
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2.3. Municipalities
MassGIS 2020 municipal boundaries were created by MassGIS by adjusting older USGS topo map town
boundaries to connect the survey points of a community. In many areas, boundary creation was simply a
matter of "connecting the dots" from one boundary point to the next. Where boundaries follow a
stream/river or road right-of-way (ROW) the boundary was approximately delineated using the 2001 Aerial
Imagery as a base. Figure 2-3 shows the municipal boundaries within the Taunton River watershed.
Figure 2-3. A map showing the municipal boundaries in the Taunton River watershed.
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2.4. Buildings
MassGIS 2021 buildings dataset consists of 2-dimensional roof outlines ("roof-prints") for all buildings larger
than 150 square feet in all of Massachusetts. In 2019, MassGIS refreshed the data to abaseline of 2016 and
continues to update features using newer aerial imagery that allows MassGIS staff to remove, modify and
add structures to keep up with more current ground conditions. In March 2021, the layer was updated with
2017 and 2018 structure review edits along with the first data edits compiled atop spring 2019 imagery. In
July 2021, MassGIS completed the statewide update based on 2019 imagery. Figure 2-4 shows the building
boundaries within the Taunton River watershed.
Figure 2-4. A map showing the building footprints in the Taunton River watershed.
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2.5. Baseline HRUs Layer
Hydrologic Response Units (HRUs) are key components of watershed modeling and spatially represent
areas of similar physical characteristics that drive watershed hydrology and water quality. A baseline HRU
layer representing the land use, land cover, soil, and slope characteristics in the Taunton River watershed
was developed during Phase 1 of the FDC project (Paradigm Environmental and Great Lakes
Environmental Center, 2021). The baseline HRU layer for the Taunton River watershed combines spatial
information into a single raster layer with 36 unique categories. The unit-area HRU time series for the
baseline conditions were developed using the most recent 20-year period of observed meteorological
boundary conditions and calibrating the rainfall-runoff response on each HRU along with reach routing
processes in the LSPC model under Phase 1 of the FDC project.
Figure 2-5 shows the spatial overlay process used to develop the baseline HRU categories. During the HRU
development process, raw spatial data were reclassified into relevant categories. Table 2-2 shows the
reclassification of Mass GIS 2016 land use and land cover data to derive the modeled land use categories in
the Opti-Tool. Table 2-3 shows the reclassification of the Soil Survey Geographic (SSURGO) database and
the State Soil Geographic (STATSG02) database to derive the modeled Hydrologic Soil Group (HSG)
categories in the Opti-Tool. Table 2-4 shows the reclassification of the percent slope attribute to derive the
modeled slope categories in the Opti-Tool. Table 2-5 shows the final 36 HRU categories developed for the
Taunton River watershed. Figure 2-6 shows the spatial location of the baseline HRUs in the Taunton River
watershed.
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Figure 2-5. Baseline HRUs spatial overlay process (from top to bottom: land use - land cover, soil, and slope layers)
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Table 2-2. Land use - land cover reclassification
Land Cover
Code
Land Cover
Description
Land Use
Code
Land Use
Description
Land Use
Reclassification
Cover Type
2
Impervious
0
Unknown
Paved Open Land
Impervious
2
Impervious
2
Open land
Paved Open Land
Impervious
2
Impervious
3
Commercial
Paved Commercial
Impervious
2
Impervious
4
Industrial
Paved Industrial
Impervious
2
Impervious
6
Forest
Paved Forest
Impervious
2
Impervious
7
Agriculture
Paved Agriculture
Impervious
2
Impervious
8
Recreation
Paved Open Land
Impervious
2
Impervious
9
Tax exempt
Paved Open Land
Impervious
2
Impervious
10
Mixed use, primarily
residential
Paved Medium
Density Residential
Impervious
2
Impervious
11
Residential - single
family
Paved Low Density
Residential
Impervious
2
Impervious
12
Residential - multi-
family
Paved High Density
Residential
Impervious
2
Impervious
13
Residential - other
Paved Medium
Density Residential
Impervious
2
Impervious
20
Mixed use, other
Paved Open Land
Impervious
2
Impervious
30
Mixed use, primarily
commercial
Paved Commercial
Impervious
2
Impervious
55
Right-of-way
Paved Transportation
Impervious
2
Impervious
88
Water
Paved Open Land
Impervious
5
Developed Open
Space
N/A
N/A
Developed Open
Space
Pervious
6
Cultivated
N/A
N/A
Agriculture
Pervious
7
Pasture/Hay
N/A
N/A
Agriculture
Pervious
8
Grassland
N/A
N/A
Agriculture
Pervious
9
Deciduous Forest
N/A
N/A
Forest
Pervious
10
Evergreen Forest
N/A
N/A
Forest
Pervious
12
Scrub/Shrub
N/A
N/A
Agriculture
Pervious
13
Palustrine Forested
Wetland
N/A
N/A
Forested Wetland
Pervious
14
Palustrine
Scrub/Shrub Wetland
N/A
N/A
Non-Forested
Wetland
Pervious
15
Palustrine Emergent
Wetland
N/A
N/A
Non-Forested
Wetland
Pervious
18
Estuarine Emergent
Wetland
N/A
N/A
Water
Pervious
19
Unconsolidated Shore
N/A
N/A
Water
Pervious
20
Bare Land
N/A
N/A
Developed Open
Space
Pervious
21
Water
N/A
N/A
Water
Pervious
22
Palustrine Aquatic Bed
N/A
N/A
Water
Pervious
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Table 2-3. Soil - HSG reclassification
HSG -
SSURGO
HSG -
STATSG02
HSG
Reclassification
Justification
No Data
A
A
When no other information was available, the STATSG02
data layer was used to fill the gaps.
No Data
B
B
No Data
C
C
No Data
D
D
A
N/A
A
A/D
N/A
D
Dual HSGs were represented, and their undrained condition
('D') was selected as a conservative choice.
B
N/A
B
-
B/D
N/A
D
Dual HSGs were represented, and their undrained condition
('D') was selected as a conservative choice.
C
N/A
C
-
C/D
N/A
D
Dual HSGs were represented, and their undrained condition
('D') was selected as a conservative choice.
D
N/A
D
-
Table 2-4. Percent slope reclassification
Percent Slope
Slope Reclassification
<5%
Low
5% -15%
Medium
>15%
High
Table 2-5. Summary of final HRU categories
HRU Code
HRU Description
Land Use
Soil
Slope
Land Cover
1000
Paved Forest
Paved Forest
N/A
N/A
Impervious
2000
Paved Agriculture
Paved Agriculture
N/A
N/A
Impervious
3000
Paved Commercial
Paved Commercial
N/A
N/A
Impervious
4000
Paved Industrial
Paved Industrial
N/A
N/A
Impervious
5000
Paved Low Density Residential
Paved Low Density Residential
N/A
N/A
Impervious
6000
Paved Medium Density
Residential
Paved Medium Density
Residential
N/A
N/A
Impervious
7000
Paved High Density Residential
Paved High Density Residential
N/A
N/A
Impervious
8000
Paved Transportation
Paved Transportation
N/A
N/A
Impervious
9000
Paved Open Land
Paved Open Land
N/A
N/A
Impervious
10110
Developed OpenSpace-A-Low
Developed OpenSpace
A
Low
Pervious
10120
Developed OpenSpace-A-Med
Developed OpenSpace
A
Med
Pervious
10210
Developed OpenSpace-B-Low
Developed OpenSpace
B
Low
Pervious
10220
Developed OpenSpace-B-Med
Developed OpenSpace
B
Med
Pervious
10310
Developed OpenSpace-C-Low
Developed OpenSpace
C
Low
Pervious
10320
Developed OpenSpace-C-Med
Developed OpenSpace
C
Med
Pervious
10410
Developed OpenSpace-D-Low
Developed OpenSpace
D
Low
Pervious
10420
Developed OpenSpace-D-Med
Developed OpenSpace
D
Med
Pervious
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HRU Code
HRU Description
Land Use
Soil
Slope
Land Cover
11000
Forested Wetland
Forested Wetland
N/A
N/A
Pervious
12000
Non-Forested Wetland
Non-Forested Wetland
N/A
N/A
Pervious
13110
Forest-A-Low
Forest
A
Low
Pervious
13120
Forest-A-Med
Forest
A
Med
Pervious
13210
Forest-B-Low
Forest
B
Low
Pervious
13220
Forest-B-Med
Forest
B
Med
Pervious
13310
Forest-C-Low
Forest
C
Low
Pervious
13320
Forest-C-Med
Forest
C
Med
Pervious
13410
Forest-D-Low
Forest
D
Low
Pervious
13420
Forest-D-Med
Forest
D
Med
Pervious
14110
Agr
culture-A-Low
Agr
culture
A
Low
Pervious
14120
Agr
culture-A-Med
Agr
culture
A
Med
Pervious
14210
Agr
culture-B-Low
Agr
culture
B
Low
Pervious
14220
Agr
culture-B-Med
Agr
culture
B
Med
Pervious
14310
Agr
culture-C-Low
Agr
culture
C
Low
Pervious
14320
Agr
iculture-C-Med
Agr
iculture
C
Med
Pervious
14410
Agr
iculture-D-Low
Agr
iculture
D
Low
Pervious
14420
Agr
iculture-D-Med
Agr
iculture
D
Med
Pervious
15000
Water
Water
N/A
N/A
Pervious
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HRU Classification
Agriculture-A-Low
Agriculture-A-Med
Agriculture-B-Low
Agriculture-B-Med
Agriculture-C-Low
Agriculture-C-Med
Agriculture-D-Low
Agriculture-D-Med
Developed OpenSpace-A-Low
Developed OpenSpace-A-Med
Developed OpenSpace-B-Low
Developed OpenSpace-B-Med
Developed OpenSpace-C-Low
Developed OpenSpace-C-Med
Developed OpenSpace-D-Low
Developed OpenSpace-D-Med
Forest-A-Low
Forest-A-M ed
Forest-B-Low
Forest-B-Med
Forest-C-Low
Forest-C-Med
Forest-D-Low |
Forest-D-M ed
Forested Wetland
Non-Forested Wetland
Paved Agriculture
Paved Commercial
Paved Forest
| Paved High Density Residential
| Paved Industrial
Paved Low Density Residential
Paved Medium Density Residential
Paved Open Land
| Paved Transportation
| V\foter
0 1.5 3 6
12
¦ Miles
Figure 2-6. A map showing the 2016 baseline HRU raster layer for the Taunton River watershed.
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3. DEVELOPMENT OF FUTURE HRU LAYER FOR TAUNTON
RIVER WATERSHED
To simulate future hydrological conditions within the Taunton River watershed, the NELF projected 2060
land cover datasets were analyzed and processed to update the 2016 baseline HRU layer. The baseline HRUs
were built with high-resolution (1-m) impervious cover data across the Taunton River watershed. However,
the projected 2060 land cover data is at 30-m; this coarser resolution also does not provide the percent
imperviousness associated with the given land use classification which is needed to develop HRUs.
Additionally, the land use classification is much coarser and does not differentiate between commercial,
industrial, residential, and open space but instead is lumped into just two developed categories: high-density
and low-density development. The methodology to develop a 1-m resolution future HRU layer consistent
with the baseline HRU layer includes five main steps:
1. Compare the land cover change between the recent trends 2010 and 2060 NELF datasets and preserve
the spatial footprints for the developed areas presented in the 2060 NELF dataset for developing the
future HRU layer for the Taunton River watershed.
2. Establish mapping rules between the major land use categories used in the Opti-Tool and the land use
categories used in the NELF dataset. These rules define how to disaggregate the two developed land use
(high-density and low-density) classifications from the NELF dataset into 7 major developed land use
(commercial, industrial, high-density residential, medium-density residential, low-density residential,
open land, and transportation) classifications for the Opti-Tool.
3. Estimate the percent imperviousness rules for the 7 major developed land use categories established in
step 2 by using the MassGIS 2016 land use - land cover dataset for the Taunton River watershed. These
rules are assumed to remain the same at different spatial extents. For example, the percent
imperviousness for commercial land use remains the same for future development areas regardless of
where they are located in the watershed. The projected future commercial areas in any municipal
boundary will have the same percent imperviousness as it is overall in the Taunton River watershed
based on the MassGIS 2016 land use - land cover dataset.
4. Estimate the area distribution rules between the 7 major developed land use categories (i.e., commercial,
industrial, high-density residential, medium-density residential, low-density residential, open space, and
transportation) by the municipality within the Taunton River watershed. Apply these rules to new
development areas to break down the two developed NELF categories (high-density and low-density)
into 7 developed Opti-Tool categories at the municipal level. These rules are derived at the municipality
level and remain the same within the given municipal boundary but can vary from one municipality to
another. It is assumed that area distribution between developed land use categories follows the same
trend for the projected 2060 future land use - land cover classification.
5. Identify the undeveloped areas from the baseline HRU layer that are subject to future development based
on an overlay with the 2060 NELF dataset and apply the rules established in steps 3 and 4 at the
municipality level. Apply the peppered raster method developed in Phase 1 of the FDC project to convert
one-to-many HRU categories using the probabilistic raster reclassification algorithm. For example, if
there are 100 acres of forest category within a given municipality that is subject to high-density
development, then those acres are split into paved commercial, paved industrial, paved high-density
residential, paved transportation, and developed open space based on the established area distribution
rules of those developed categories within the same municipal boundary. The underlying soil (i.e., HSG)
and slope classifications remain the same as in the baseline HRU layer.
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The following sections provide more detail on the process of developing the future HRU raster layer and
summarize the change in the baseline HRUs due to the projected future development in the Taunton River
watershed.
3.1. Land Cover Change Between 2010 and 2060 NELF Dataset
Within the Taunton River watershed, both low- and high-density development increased between the NELF
2010 and 2060 recent trend datasets (Table 3-1). This is generally due to the conversion of unprotected forest
areas to developed areas. However, the recent trends underpinning the NELF datasets also indicate an
increase in conserved forests. The baseline HRUs developed under Phase 1 of the FDC project use higher
resolution MassGIS 2016 land use - land cover data, so the NELF 2060 projected future dataset was
overlayed with the baseline HRU layer to identify the areas subject to projected future development.
Table 3-1. NELF recent trend 2010 and 2060 land cover comparison
NELF Land Use Classification
Recent Trend 2010 (acre)
Recent Trend 2060 (acre)
Change (%)
Agriculture
23,735
24,568
4%
Conserved Forest
44,372
79,238
79%
High Density Development
14,889
20,906
40%
Low Density Development
79,795
112,477
41%
Other
32,758
32,758
0%
Unprotected Forest
129,871
55,474
-57%
Water
16,032
16,032
0%
3.2. Mapping Between Opti-Tool and NELF Land Use Classification
Table 3-2 shows a mapping table between NELF, Continuous Change Detection and Classification (CCDC),
and National Land Cover Dataset (NLCD) datasets. These datasets were used in the NELF project and,
where CCDC data was not available, NLCD data was used to fill the gaps. The CCDC and NLCD maps
were reclassified to a common legend consisting of High-Density Development, Low-Density Development,
Forest, Agriculture, Water, and a composite "Other" class for developing the NELF datasets (Thompson et
al., 2017). Based on the land use description shown in Table 3-2, new mapping rules were developed to
disaggregate the NELF classification into the Opti-Tool land use classification as shown in Table 3-3. These
mapping rules are assumed to remain the same across any municipal boundary within the Taunton River
watershed.
Table 3-2. Reclassification Scheme for CCDC and NLCD Data for NELF Land Cover (Thompson et al., 2017)
NELF
Classification
CCDC Class
CCDC Class
Description
NLCD 2001/2011
Class
NLCD 2001/2011 Class
Description
High Density
Developed
Commercial/
Industrial
Area of urban
development;
impervious surface
area target 80-100%
Developed High
Intensity
Highly developed areas where
people reside or work in high
numbers. Examples include
apartment complexes,
rowhouses, and commercial
/industrial. Impervious surfaces
account for 80% to 100% of the
total cover.
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NELF
Classification
CCDC Class
CCDC Class
Description
NLCD 2001/2011
Class
NLCD 2001/2011 Class
Description
High Density
Residential
Area of residential
urban development
with some
vegetation;
impervious surface
area target 50-80%
Developed,
Medium
Intensity
Areas with a mixture of
constructed materials and
vegetation. Impervious surfaces
account for 50% to 79% of the
total cover. These areas most
commonly include single-family
housing units.
Low Density
Developed
Low Density
Residential
Area of residential
urban development
with significant
vegetation;
impervious surface
area target 0-50%
Developed, Low
Intensity
Areas with a mixture of
constructed materials and
vegetation. Impervious surfaces
account for 20% to 49% percent
of total cover. These areas most
commonly include single-family
housing units.
Developed,
Open Space
Areas with a mixture of some
constructed materials, but
mostly vegetation in the form of
lawn grasses. Impervious
surfaces account for less than
20% of total cover. These areas
most commonly include large-lot
single-family housing units,
parks, golf courses, and
vegetation planted in developed
settings for recreation, erosion
control, or aesthetic purposes.
Agriculture
Agriculture
Non-woody
cultivated plants;
includes cereal and
broadleaf crops
Pasture/Hay
Areas of grasses, legumes, or
grass-legume mixtures are
planted for livestock grazing or
the production of seed or hay
crops, typically on a perennial
cycle. Pasture/hay vegetation
accounts for greater than 20% of
total vegetation.
Cultivated Crops
Areas used for the production of
annual crops, such as corn,
soybeans, vegetables, tobacco,
and cotton, and also perennial
woody crops such as orchards
and vineyards. Crop vegetation
accounts for greater than 20%
of total vegetation. This class
also includes all land being
actively tilled.
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NELF
Classification
CCDC Class
CCDC Class
Description
NLCD 2001/2011
Class
NLCD 2001/2011 Class
Description
Forest
Mixed
Forest
Forested land with at
least 40% tree
canopy cover
comprising no more
than 80% of either
evergreen needle
leaf or deciduous
broadleaf cover
Mixed Forest
Areas dominated by trees are
generally greater than 5 meters
tall, and greater than 20% of
total vegetation cover. Neither
deciduous nor evergreen species
are greater than 75% of the total
tree cover.
Deciduous
Broadleaf
Forest
Forested land with at
least 40% tree
canopy cover
comprising more
than 80% deciduous
broadleaf cover
Deciduous
Forest
Areas dominated by trees are
generally greater than 5 meters
tall, and greater than 20% of
total vegetation cover. More
than 75% of the tree species
shed foliage simultaneously in
response to seasonal change.
Evergreen
Needleleaf
Forest
Forested land with at
least 40% tree
canopy cover
comprising more
than 80% evergreen
needle leaf cover
Evergreen Forest
Areas dominated by trees are
generally greater than 5 meters
tall, and greater than 20% of
total vegetation cover. More
than 75% of the tree species
maintain their leaves all year.
Canopy is never without green
foliage.
Woody
Wetland
An additional class of
wetland that tries to
separate wetlands
with considerable
biomass from mainly
herbaceous wetlands
Woody
Wetlands
Areas where forest or shrubland
vegetation accounts for greater
than 20% of vegetative cover
and the soil or substrate is
periodically saturated with or
covered with water.
Shrub/Scrub
Areas dominated by shrubs; less
than 5 meters tall with shrub
canopy typically greater than
20% of total vegetation. This
class includes true shrubs, young
trees in an early successional
stage, or trees stunted from
environmental conditions.
Other
Wetland
Vegetated land
(woody and non-
woody) with
inundation from high
water table; includes
swamps, salt, and
freshwater marshes
and tidal
rivers/mudflats
Emergent
Herbaceous
Wetlands
Areas where perennial
herbaceous vegetation accounts
for greater than 80% of
vegetative cover and the soil or
substrate is periodically
saturated with or covered with
water.
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NELF
Classification
CCDC Class
CCDC Class
Description
NLCD 2001/2011
Class
NLCD 2001/2011 Class
Description
Herbaceous
/ Grassland
Non-woody naturally
occurring or slightly
managed plants;
includes pastures
Barren Land
(Rock/Sand/Clay)
Areas of bedrock, desert
pavement, scarps, talus, slides,
volcanic material, glacial debris,
dunes, strip mines, gravel pits,
and other accumulations of
earthen material. Generally,
vegetation accounts for less
than 15% of total cover.
Bare
Non-vegetated land
comprised of above
60% rock, sand, or
soil
Water
Water
Lakes, ponds, rivers,
and ocean
Open Water
Areas of open water, generally
with less than 25% cover of
vegetation or soil.
Table 3-3. Mapping table between NELF and Opti-Tool land use classification
NELF ID
NELF Land Use Classification
Opti-Tool Land Use Classification
Commercial
1
High Density Development
Industrial
High-Density Residential
Transportation
Low-Density Residential
2
Low Density Development
Medium-Density Residential
Open Land
Transportation
3
Unprotected Forest
Forest
4
Conserved Forest
5
Agriculture
Agriculture
6
Other
Wetland
7
Water
Water
3.3. Percent Imperviousness for Developed Land Use Classification
Using the MassGIS 2016 land use - land cover dataset, the percent imperviousness was estimated for the 7
developed land use categories used in the Opti-Tool (Table 3-4). As well as the total percentage of IC, the
percent of IC from buildings (i.e., roof-area) was calculated for each developed land use classification. These
rules were developed at the Taunton River watershed scale and are assumed to hold at any spatial scale
within the Taunton River watershed. For example, the projected future commercial land use in any
municipality within the Taunton River watershed will have 66.8% impervious area, with 23.8% building
rooftops representing 23.8% of that total IC.
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Table 3-4. Summary of percent imperviousness for developed land use classification
Developed Land Use Classification
Total Impervious Cover (%)
Buildings (% of Total IC)
Commercial
66.8%
23.8%
Industrial
75.3%
38.2%
High-Density Residential
51.4%
35.4%
Transportation
80.6%
0.0%
Low-Density Residential
31.5%
40.1%
Medium-Density Residential
43.0%
29.5%
Open Land
30.0%
19.9%
3.4. Developed Land Use Distribution by Municipality in Taunton River Watershed
For each municipality within the Taunton River watershed, the breakdown of developed land use area was
calculated from the MassGIS 2016 land use - land cover data. This allowed conversion between the NELF
and Opti-Tool classes (as shown in Table 3-3). Table 3-5 summarizes high-density developed areas into
commercial, industrial, high-density residential, and transportation categories. Table 3-6 summarizes the
breakdown of low-density developed areas into low-density residential, medium-density residential, open
space, and transportation categories. These rules were developed at the municipality level to allow different
development patterns across different municipalities based on the baseline development trends. It was
assumed that the area distribution between the developed land use categories shown in Table 3-5 and Table
3-6 holds for the projected future development within the same municipal boundary.
Table 3-5. Summary of high-density development land use area distribution by municipality in the Taunton River
watershed
Municipality
High-Density Development (MassGIS 2016)
ID
Name
Commercial
Industrial
High Density
Residential
Transportation
1
ABINGTON
40.5%
0.7%
34.4%
24.4%
16
ATTLEBORO
10.3%
43.8%
16.3% 29.6%
18
AVON
28.8%
38.0%
5.3% 27.9%
27
BERKLEY
31.6%
4.7%
27.7% 36.0%
42
BRIDGEWATER
22.9%
11.7%
40.7% 24.7%
44
BROCKTON
34.8%
8.9%
31.8% 24.5%
52
CARVER
43.2%
7.3%
6.0% 43.6%
72
DARTMOUTH
32.3%
16.2%
24.8% 26.7%
76
DIGHTON
35.8%
20.6%
16.1% 27.5%
83
EAST BRIDGEWATER
27.2%
19.3%
26.1% 27.4%
88
E ASTON
32.4%
15.2%
26.8% 25.7%
95
FALL RIVER
16.3%
28.0%
30.2% 25.5%
99
FOXBOROUGH
39.4%
8.1%
20.1% 32.4%
102
FREETOWN
23.9%
38.0%
6.4% 31.6%
118
HALIFAX
34.7%
6.9%
35.0% 23.4%
123
HANSON
28.4%
24.7%
20.1%
26.8%
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Municipality High-Density Development (MassGIS 2016)
ID
Name
Commercial
Industrial
High Density
Residential
Transportation
133
HOLBROOK
36.2%
14.3%
18.7%
30.8%
145
KINGSTON
0.0%
0.0%
62.7%
37.3%
146
LAKEVILLE
37.0%
21.7%
15.7%
25.6%
167
MANSFIELD
25.1%
31.6%
15.2%
28.2%
182
MIDDLEBOROUGH
38.8%
10.3%
19.1%
31.9%
201
NEW BEDFORD
33.9%
0.0%
30.3%
35.8%
208
NORFOLK
32.3%
16.2%
24.8%
26.7%
211
NORTH ATTLEBOROUGH
64.9%
0.0%
0.0%
35.1%
218
NORTON
21.2%
19.9%
32.2%
26.7%
231
PEMBROKE
20.6%
9.6%
41.5%
28.3%
238
PLAINVILLE
46.0%
8.1%
20.9%
25.0%
239
PLYMOUTH
61.0%
0.0%
24.4%
14.6%
240
PLYMPTON
54.1%
9.9%
8.6%
27.3%
245
RAYNHAM
46.5%
9.5%
15.0%
28.9%
247
REHOBOTH
31.5%
0.0%
37.9%
30.5%
250
ROCHESTER
0.0%
0.0%
63.3%
36.7%
251
ROCKLAND
53.3%
0.0%
20.1%
26.6%
266
SHARON
47.4%
0.3%
10.3%
42.0%
273
SOMERSET
36.5%
12.8%
23.7%
27.0%
285
STOUGHTON
29.4%
34.4%
8.1%
28.1%
292
SWANSEA
9.4%
0.0%
61.2%
29.5%
293
TAUNTON
32.1%
12.0%
32.7%
23.3%
307
WALPOLE
32.3%
16.2%
24.8%
26.7%
322
WEST BRIDGEWATER
34.2%
26.6%
11.3%
27.8%
336
WEYMOUTH
0.1%
0.0%
65.9%
34.0%
338
WHITMAN
26.8%
12.5%
34.3%
26.3%
350
WRENTHAM
30.9%
5.6%
29.5%
34.0%
Table 3-6. Summary of low-density development land use area distribution by the municipality in the Taunton River
watershed
Municipality
Low-Density Development (MassGIS 2016)
ID
Name
Medium Density
Residential
Low Density
Residential
Open Land
Transportation
1
ABINGTON
0.6%
64.6%
20.4%
14.4%
16
ATTLEBORO
0.0%
72.9%
10.9%
16.1%
18
AVON
0.2%
57.9%
27.3%
14.6%
27
BERKLEY
5.7%
58.5%
12.9%
22.9%
42
BRIDGEWATER
1.3%
51.4%
32.8%
14.6%
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Municipality
Low-Density Development (MassGIS 2016)
ID
Name
Medium Density
Residential
Low Density
Residential
Open Land
Transportation
44
BROCKTON
0.6%
52.5%
32.8%
14.1%
52
CARVER
1.6%
59.2%
12.3%
26.8%
72
DARTMOUTH
2.1%
57.1%
24.9%
15.9%
76
DIGHTON
3.2%
53.5%
28.0%
15.3%
83
EAST BRIDGEWATER
1.8%
61.0%
21.5%
15.7%
88
E ASTON
0.2%
58.4%
26.9%
14.6%
95
FALL RIVER
2.1%
41.6%
42.0%
14.3%
99
FOXBOROUGH
1.3%
54.8%
24.8%
19.1%
102
FREETOWN
6.2%
52.3%
24.1%
17.4%
118
HALIFAX
4.0%
66.3%
15.9%
13.8%
123
HANSON
1.9%
58.8%
24.3%
14.9%
133
HOLBROOK
1.2%
72.5%
8.4%
17.9%
145
KINGSTON
0.0%
31.0%
42.7%
26.3%
146
LAKEVILLE
0.7%
67.9%
17.3%
14.0%
167
MANSFIELD
0.5%
66.1%
17.9%
15.4%
182
MIDDLEBOROUGH
10.7%
50.6%
19.4%
19.3%
201
NEW BEDFORD
0.9%
62.4%
14.1%
22.7%
208
NORFOLK
0.0%
89.4%
0.2%
10.4%
211
NORTH ATTLEBOROUGH
0.0%
70.4%
9.3%
20.2%
218
NORTON
3.1%
59.0%
22.3%
15.6%
231
PEMBROKE
1.2%
69.3%
12.1%
17.4%
238
PLAINVILLE
0.1%
54.4%
31.4%
14.0%
239
PLYMOUTH
0.0%
81.3%
10.8%
7.9%
240
PLYMPTON
6.4%
62.3%
16.0%
15.4%
245
RAYNHAM
1.4%
56.9%
25.3%
16.4%
247
REHOBOTH
0.5%
73.5%
6.9%
19.2%
250
ROCHESTER
2.9%
52.1%
18.6%
26.4%
251
ROCKLAND
0.0%
84.0%
0.6%
15.4%
266
SHARON
0.0%
67.3%
6.6%
26.1%
273
SOMERSET
0.3%
68.2%
16.0%
15.5%
285
STOUGHTON
1.4%
66.8%
16.7%
15.1%
292
SWANSEA
0.3%
66.2%
13.8%
19.7%
293
TAUNTON
0.5%
52.9%
33.3%
13.3%
307
WALPOLE
0.0%
76.0%
0.1%
23.9%
322
WEST BRIDGEWATER
5.0%
50.2%
29.5%
15.3%
336
WEYMOUTH
0.0%
73.3%
2.7%
24.1%
338
WHITMAN
1.7%
60.6%
22.2%
15.5%
350
WRENTHAM
0.9%
43.0%
35.3%
20.9%
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3.5. Future HRU Layer for the Taunton River Watershed
Based on the relationships established between the MassGIS 2016 baseline and NELF future datasets, the
future mapped HRU area distribution was estimated for each municipality based on the change from
baseline undeveloped areas (e.g., agriculture and forest) to the developed areas in the projected NELF data.
The spatial overlay process shown in Figure 3-1 illustrates how the relevant layers are aligned. Any areas
that are undeveloped in the projected future NELF data layer maintain their baseline HRU values; areas
that are undeveloped in the baseline but subject to development in the future layer are reclassified to the
appropriate class from the baseline HRU layer. As an example, parcels of unprotected forest within a
municipality boundary that are subject to projected future development are converted to developed parcels;
the percentage distribution rules for the detailed developed land use categories (Table 3-5 and Table 3-6) and
the corresponding imperviousness rules (Table 3-4) are used to predict the future HRUs. Table 3-7
summarizes the change in each HRU category between the baseline and future HRUs; Figure 3-2 shows the
spatial distribution of future HRUs. Figure 3-3 shows the comparison between coarse resolution 2060 NELF
classification and high resolution 2060 Future HRUs for the Upper Hodges Brook sub-watershed.
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Figure 3-1. Mapped future HRU spatial overlay process (from top to bottom: NELF 2060 land cover, baseline HRUs,
municipalities, and final future HRU layer).
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Table 3-7. Comparison of HRU area distribution between the MassGIS 2016 baseline and NELF 2060 future conditions
in the Taunton River watershed
HRU
Code
Land Use Classification
Land Cover
Soil
Slope
Baseline
(acre)
Future
(acre)
mtM
1,000
Paved Forest
Impervious
N/A
N/A
9
9
0.0%
2,000
Paved Agriculture
Impervious
N/A
N/A
128
158
23.0%
3,000
Paved Commercial
Impervious
N/A
N/A
4,858
6,873
41.5%
4,000
Paved Industrial
Impervious
N/A
N/A
2,745
3,892
41.8%
5,000
Paved Low Density Residential
Impervious
N/A
N/A
9,951
20,717
108.2%
6,000
Paved Medium Density
Residential
Impervious
N/A
N/A
489
1,133
131.7%
7,000
Paved High Density Residential
Impervious
N/A
N/A
2,856
4,041
41.5%
8,000
Paved Transportation
Impervious
N/A
N/A
11,852
21,709
83.2%
9,000
Paved Open Land
Impervious
N/A
N/A
4,138
8,377
102.4%
10,110
Developed OpenSpace
Pervious
A
Low
13,210
18,203
37.8%
10,120
Developed OpenSpace
Pervious
A
Med
5,864
14,785
152.1%
10,210
Developed OpenSpace
Pervious
B
Low
3,621
5,792
59.9%
10,220
Developed OpenSpace
Pervious
B
Med
1,897
4,483
136.3%
10,310
Developed OpenSpace
Pervious
C
Low
4,326
7,243
67.4%
10,320
Developed OpenSpace
Pervious
C
Med
2,488
4,809
93.3%
10,410
Developed OpenSpace
Pervious
D
Low
7,944
17,328
118.1%
10,420
Developed OpenSpace
Pervious
D
Med
1,604
3,478
116.9%
11,000
Forested Wetland
Pervious
N/A
N/A
66,463
66,463
0.0%
12,000
Non-Forested Wetland
Pervious
N/A
N/A
9,734
9,734
0.0%
13,110
Forest
Pervious
A
Low
17,071
7,615
-55.4%
13,120
Forest
Pervious
A
Med
33,959
17,511
-48.4%
13,210
Forest
Pervious
B
Low
7,649
3,553
-53.6%
13,220
Forest
Pervious
B
Med
10,948
6,320
-42.3%
13,310
Forest
Pervious
C
Low
12,123
6,470
-46.6%
13,320
Forest
Pervious
C
Med
9,548
4,954
-48.1%
13,410
Forest
Pervious
D
Low
43,764
26,559
-39.3%
13,420
Forest
Pervious
D
Med
9,331
5,850
-37.3%
14,110
Agr
culture
Pervious
A
Low
4,780
4,426
-7.4%
14,120
Agr
culture
Pervious
A
Med
3,095
3,590
16.0%
14,210
Agr
culture
Pervious
B
Low
1,204
1,187
-1.4%
14,220
Agr
culture
Pervious
B
Med
1,106
1,090
-1.4%
14,310
Agr
iculture
Pervious
C
Low
1,925
1,966
2.1%
14,320
Agr
iculture
Pervious
C
Med
1,092
1,178
7.9%
14,410
Agr
iculture
Pervious
D
Low
10,907
11,157
2.3%
14,420
Agr
iculture
Pervious
D
Med
1,146
1,173
2.4%
15,000
Water
N/A
N/A
N/A
17,628
17,628
0.0%
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FDC 2A Project Draft Project Report
HRU Classification
Ag ri c u Itu re-A- Low
Agriculture-A-Med
Agriculture-B-Low
Agriculture-B-Med
Agriculture-C-Low
Agriculture-C-Med
Agriculture-D-Low
Agriculture-D-Med
Developed OpenSpace-A-Low
Developed OpenSpace-A-Med
Developed OpenSpace-B-Low
Developed OpenSpace-B-Med
Developed OpenSpace-C-Low
Developed OpenSpace-C-Med
Developed OpenSpace-D-Low
Developed OpenSpace-D-Med
Forest-A-Low
Forest-A-Med
Forest-B-Low
Forest-B-Med
Forest-C-Low
Forest-C-Med
Forest-D-Low
Forest-D-Med
Forested Wetland
Non-Forested Wetland
Paved Agriculture
Paved Commercial
Paved Forest
Paved High-Density Residential
Paved Industrial
Paved Low-Density Residential
Paved Medium-Density Residential
Paved Open Land
| Paved Transportation
Vteter
0 1.5 3 6
12
h Miles
Figure 3-2, A map showing the 2060 future HRU raster layer for the Taunton River watershed,
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Recent Trend 2060
| j High Density Development
Low Density Development
Unprotected Forest
Conserved Forest
Agriculture
~ Other
Water
HRU Classification
Agriculture-A-Low
Agriculture-A-Med
Agriculture-B-Low
Agriculture-B-Med
Agriculture-C-Low
|_. Agriculture-C-Med
Agriculture-D-Low
Agriculture-D-Med
Developed OpenSpace-A-Low
Developed OpenSpace-A-Med
Developed OpenSpace-B-Low
Developed OpenSpace-B-Med
Developed OpenSpace-C-Low
Developed OpenSpace-C-Med
Developed OpenSpace-D-Low
Developed OpenSpace-D-Med
I Forest-A-Low
| Forest-A-Med
Forest-B-Low
Forest-B-Med
| Forest-C-Low
| Forest-C-Med
Forest-D-Low
Forest-D-Med
Forested Wetland
Non-Forested Wetland
Paved Agriculture
Paved Commercial
Paved Forest
Paved High-Density Residential
/
Paved Industrial
V _.| tr- f'
Paved Low-Density Residential
Paved Medium-Density Residential
Paved Open Land
Paved Transportation
Vteter
0 0.175 0.35 0.7
1.4
¦ Miles
Figure 3-3. A map showing the comparison between the 30-m resolution 2060 future NELF layer (left) and 1-m
resolution 2060 future HRU layer (right) for the Upper Hodges Brook sub-watershed.
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4. SELECTION OF FUTURE CLIMATE MODELS
To simulate future climate conditions, meteorological time series from three GCMs were selected from those
used in FDC Phase 1 (Table 4-1) (Paradigm Environmental and Great Lakes Environmental Center, 2021).
The GCMs for use in Phase 2 were selected to represent the greatest increase in both precipitation and
temperature, as well as the modeled ecodeficits and ecosurpluses for the Upper Hodges Brook watershed
from FDC Phase 1 (Figure 4-1 and Table 4-2). As shown in Table 4-1, these climate projections are from
Representative Concentration Pathway (RCP) 8.5, which represents a scenario in which carbon emissions
continue to climb at historical rates (in contrast, RCP 4.5 predicts a stabilization of carbon emissions by
2100). Using these models in conjunction with the projected future land cover conditions should provide
"bookends" within which to evaluate innovative stormwater control measures and protective ordinances.
The downscaled meteorological data for the selected GCMs will be used to drive the LSPC hydrology model
in FDC Phase 2.
Table 4-1. FDC Phase 1 selected models from ensemble results for future climate projections (2079-2099)
RCP
Scenario1
Ecosuplus Model
Ecodeficit Model
RCP 4.5
Dry
hadgem2-cc-l
mpi-esm-mr-1
Median
bcc-csml-l-m-1
bcc-csml-l-m-1
Wet
bcc-csm 1-1-1
miroc-esm-chem-1
RCP 8.5
Dry
inmcm4-l
miroc-esm-1
Median
cesml-cam5-l
cesml-cam5-l
Wet
cesml-bgc-1
mri-cgcm3-l
1: Dry, Median, and Wet correspond to the 20th, 50th, and 80th percentile hydrological responses.
Models chosen for FDC Phase 2 are highlighted in yellow.
12
C
¦B ^
n:
m
=- 0
m
M
C
ro
u _4
-8
-12
i
i
i
i
i
1
1
X WA
O Wet
i
i
--!
1
1
1 Mean
Dry
l
Oi Wet
' Mean
!
i
i
Vledian
(5
Dry
s) Med©nDry
; Median
1
i
i
i
i
1
1
1
1
1
i
i
i
i
i
1
1
1
1
i
i
i
i
O Ecosurplus4.5
X Ecodeficit 4.5
O Ecosurplus8.5
X Ecodeficit 8.5
-18 -15 -12 -9 -6 -3 0 3 6
% change in temperature
12
15
18
Figure 4-1. Percent change in annual average precipitation and temperature from baseline conditions for the FDC
Phase 1 selected models presented in Table 4-1.
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Table 4-2. Summary of ecosurpluses and ecodeficits (million gallons per year) within the Upper Hodges Brook
watershed for RCP 4.5 and 8.5 scenarios
Ecodeficit models
Scenario
Ecodeficits
Ecosurplus
Dry
Median
Wet
Dry
Median
Wet
RCP 4.5
98.1
78.8
36.1
19.0
43.1
31.8
RCP 8.5
121.4
91.1
49.2
7.1
14.6
90.8
Ecosurplus models
Scenario
Ecodeficits
Ecosurplus
Dry
Median
Wet
Dry
Median
Wet
RCP 4.5
122.0
78.8
52.1
7.6
43.1
60.3
RCP 8.5
112.2
91.1
44.1
14.7
14.6
57.6
5. COMPARISON OF EXISTING AND FUTURE (IC AND CLIMATE)
CONDITIONS IN THE TAUNTON RIVER WATERSHED
This section compares the results between the 2016 baseline, projected 2060 future land use - land cover
conditions, and the three selected future climate scenarios. These comparisons include future estimates of
IC (assuming conventional development patterns) and estimates of unattenuated average annual run-off
volume, groundwater recharge, evapotranspiration, and nutrients (TN and TP) load export for both existing
and future land cover and climate conditions for each municipality within the Taunton River watershed.
5.1. Change in Impervious Cover by 2060 in Taunton River Watershed
The change in impervious areas between the 2016 baseline and 2060 future conditions for 7 major land use
categories, transportation (TRANS), commercial (COM), industrial (IND), high-density residential (HDR),
medium-density residential (MDR), low-density residential (LDR), and open land (OPEN), are summarized
by the municipality in Table 5-1. The change in IC reflects the increase in impervious cover due to the NELF
2060 projected future development in the Taunton River watershed. The impervious cover area for each
municipality for the 2016 baseline and 2060 future conditions is given in Appendix A (Table 1 and Table 2,
respectively).
Table 5-1. Summary of increase in impervious cover by the municipality in the Taunton River watershed
Municipality Increase in Impervious Cover (acre)
ID
Name
TRANS
COM
IND
HDR
MDR
LDR
OPEN
1
ABINGTON
198.9
85.8
1.5
55.6
3.3
241.6
72.6
16
ATTLEBORO
125.4
4.1
19.4
4.9
0.0
197.9
28.3
18
AVON
95.4
29.9
44.3
4.2
0.4
94.3
42.4
27
BERKLEY
374.9
15.3
2.5
10.2
46.6
355.5
74.9
42
BRIDGEWATER
501.5
90.6
52.0
122.7
17.8
531.5
323.2
44
BROCKTON
506.2
218.2
63.0
152.4
6.8
470.6
280.0
52
CARVER
194.4
27.8
5.3
2.9
5.1
139.4
27.7
72
DARTMOUTH
0.2
0.0
0.0
0.0
0.0
0.3
0.1
76
DIGHTON
287.3
14.4
9.3
4.9
29.6
375.7
187.0
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Municipality Increase in Impervious Cover (acre)
ID
Name
TRANS
COM
IND
HDR
MDR
LDR
OPEN
83
EAST BRIDGEWATER
409.4
81.9
65.3
60.1
19.0
472.3
158.6
88
E ASTON
517.0
43.2
22.8
27.3
2.7
750.1
329.4
95
FALL RIVER
125.1
30.8
59.5
43.8
5.1
76.5
73.6
99
FOXBOROUGH
434.2
54.1
12.5
21.0
13.6
429.0
185.5
102
FREETOWN
438.9
30.8
55.1
6.3
72.8
461.1
202.1
118
HALIFAX
146.5
14.7
3.3
11.3
20.5
254.4
58.3
123
HANSON
130.9
11.2
11.0
6.1
7.8
182.8
72.1
133
HOLBROOK
60.8
26.2
11.6
10.3
1.2
54.4
6.0
145
KINGSTON
83.7
0.0
0.0
6.3
0.0
36.1
47.4
146
LAKEVILLE
386.6
36.8
24.2
12.0
9.1
676.5
164.6
167
MANSFIELD
466.5
125.5
177.2
57.9
4.9
501.0
129.5
182
MIDDLEBOROUGH
926.7
133.1
39.7
50.1
232.9
820.6
299.7
201
NEW BEDFORD
27.3
7.2
0.0
4.9
0.4
19.7
4.2
208
NORFOLK
0.9
0.3
0.2
0.2
0.0
2.0
0.0
211
NORTH ATTLEBOROUGH
6.3
0.7
0.0
0.0
0.0
8.0
1.0
218
NORTON
517.1
59.6
62.6
69.0
44.3
637.2
229.6
231
PEMBROKE
29.4
1.5
0.8
2.3
0.9
42.2
7.0
238
PLAINVILLE
116.0
72.9
14.4
25.2
0.3
104.6
57.6
239
PLYMOUTH
4.4
8.4
0.0
2.6
0.0
8.0
1.0
240
PLYMPTON
123.2
10.4
2.2
1.3
25.4
186.0
45.6
245
RAYNHAM
503.9
204.8
47.2
50.5
15.4
479.2
202.8
247
REHOBOTH
37.4
1.1
0.0
1.0
0.5
54.4
4.8
250
ROCHESTER
31.2
0.0
0.0
1.7
1.7
23.0
7.8
251
ROCKLAND
1.8
0.5
0.0
0.1
0.0
3.4
0.0
266
SHARON
259.0
7.4
0.0
1.2
0.0
254.1
23.8
273
SOMERSET
144.3
50.5
19.9
25.0
1.2
172.7
38.6
285
STOUGHTON
229.8
89.3
117.3
18.7
6.2
221.9
52.9
292
SWANSEA
49.9
0.3
0.0
1.5
0.4
64.3
12.8
293
TAUNTON
838.2
322.2
134.8
250.9
11.9
874.7
524.2
307
WALPOLE
2.7
0.6
0.3
0.3
0.0
2.6
0.0
322
WEST BRIDGEWATER
209.9
54.3
47.5
13.7
27.1
202.1
113.2
336
WEYMOUTH
3.1
0.0
0.0
1.4
0.0
2.3
0.1
338
WHITMAN
147.4
32.8
17.2
32.1
6.2
166.9
58.4
350
WRENTHAM
163.4
15.8
3.2
11.5
3.2
115.4
90.2
Total
9,857
2,015
1,147
1,186
644
10,766
4,239
Land cover classes: TRANS - transportation, COM - commercial, IND - industrial, HDR - high-density residential,
MDR - medium-density residential, LDR - low-density residential, OPEN - open land
36
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FDC 2A Project
Draft Project Report
5.2. Change in Hydrology and Water Quality by 2060 in Taunton River Watershed
Hydrology and water quality were calibrated for the modeled HRU categories during Phase 1 of the FDC
project. The pollutant build-up and wash-off parameters from the Opti-Tool SWMM models were used as a
starting point and were adjusted to calibrate the long-term annual average loading rates reported in the Opti-
Tool. The model was simulated for 20 years (Oct 2000 - Sep 2020) and annual average loading rates from
the model prediction were compared against the pollutant export rates for the similar HRU type in the Opti-
Tool. Table 5-2 presents the summary of unit-area annual average runoff, groundwater recharge (GW),
evapotranspiration (ET), and nutrients (TN and TP) loading rates by HRU from the calibrated watershed
model in Phase 1 of the FDC project. Table 5-3 to Table 5-5 presents the same summaries for the Ecodeficit
8.5 Dry, Median, and Wet climate change scenarios (Oct 2079 - Sep 2099), respectively.
Table 5-2. Summary of unit-acre-based annual average (Oct 2000 - Sep 2020) runoff volume, groundwater (GW)
recharge, evapotranspiration (ET), total nitrogen (TN) load, and total phosphorus (TP) load for the modeled
HRU types in the Wading River watershed (FDC Phase 1)
HRU
HRU Category
Runoff
(MG/ac/yr)
GW
(MG/ac/yr)
ET
(MG/ac/yr)
TN
(lb/ac/yr)
TP
(lb/ac/yr)
1000
Paved Forest
1.234
0.000
0.126
11.480
1.502
2000
Paved Agriculture
1.234
0.000
0.126
11.480
1.502
3000
Paved Commercial
1.234
0.000
0.126
15.240
1.794
4000
Paved Industrial
1.234
0.000
0.126
15.240
1.794
5000
Paved Low Density Residential
1.234
0.000
0.126
14.270
1.503
6000
Paved Medium Density Residential
1.234
0.000
0.126
14.270
1.970
7000
Paved High Density Residential
1.234
0.000
0.126
14.260
2.381
8000
Paved Transportation
1.234
0.000
0.126
10.260
1.532
9000
Paved Open Land
1.234
0.000
0.126
11.480
1.568
10110
Developed OpenSpace-A-Low
0.218
0.686
0.455
0.230
0.020
10120
Developed OpenSpace-A-Med
0.218
0.686
0.455
0.250
0.022
10210
Developed OpenSpace-B-Low
0.380
0.514
0.464
0.930
0.097
10220
Developed OpenSpace-B-Med
0.378
0.516
0.464
1.210
0.126
10310
Developed OpenSpace-C-Low
0.493
0.396
0.469
2.260
0.209
10320
Developed OpenSpace-C-Med
0.495
0.395
0.469
2.390
0.220
10410
Developed OpenSpace-D-Low
0.592
0.294
0.472
3.300
0.305
10420
Developed OpenSpace-D-Med
0.590
0.296
0.472
4.040
0.374
11000
Forested Wetland
0.331
0.159
0.876
0.520
0.109
12000
Non-Forested Wetland
0.333
0.160
0.874
0.520
0.109
13110
Forest-A-Low
0.077
0.614
0.673
0.120
0.023
13120
Forest-A-Med
0.077
0.614
0.673
0.120
0.025
13210
Forest-B-Low
0.170
0.513
0.681
0.520
0.102
13220
Forest-B-Med
0.170
0.514
0.681
0.550
0.109
13310
Forest-C-Low
0.259
0.421
0.684
1.100
0.204
13320
Forest-C-Med
0.258
0.422
0.684
1.170
0.217
13410
Forest-D-Low
0.453
0.223
0.689
1.780
0.360
13420
Forest-D-Med
0.451
0.224
0.689
1.840
0.373
37
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FDC 2A Project
Draft Project Report
HRU
HRU Category
Runoff
(MG/ac/yr)
GW
(MG/ac/yr)
ET
(MG/ac/yr)
TN
(lb/ac/yr)
TP
(lb/ac/yr)
14110
Agriculture-A-Low
0.125
0.661
0.577
0.510
0.088
14120
Agriculture-A-Med
0.124
0.661
0.577
0.540
0.093
14210
Agriculture-B-Low
0.244
0.529
0.589
2.320
0.409
14220
Agriculture-B-Med
0.244
0.530
0.589
2.490
0.439
14310
Agriculture-C-Low
0.346
0.422
0.595
5.040
0.773
14320
Agriculture-C-Med
0.345
0.423
0.595
5.410
0.829
14410
Agriculture-D-Low
0.437
0.326
0.599
8.020
1.366
14420
Agriculture-D-Med
0.436
0.328
0.599
8.490
1.447
Units: MG - million gallons, lb - pounds, ac - acre, yr - year
Table 5-3. Summary of unit-acre-based annual average (Oct 2079 - Sep 2099) runoff volume, groundwater (GW)
recharge, evapotranspiration (ET), total nitrogen (TN) load, and total phosphorus (TP) load for the
modeled HRU types in the Wading River watershed (Ecodeficit 8.5 Dry)
HRU
HRU Category
Runoff
(MG/ac/yr)
GW
(MG/ac/yr)
ET
(MG/ac/yr)
TN
(lb/ac/yr)
TP
(lb/ac/yr)
1000
Paved Forest
1.245
0.000
0.120
10.806
1.425
2000
Paved Agriculture
1.245
0.000
0.120
10.806
1.425
3000
Paved Commercial
1.245
0.000
0.120
14.351
1.631
4000
Paved Industrial
1.245
0.000
0.120
14.351
1.631
5000
Paved Low Density Residential
1.245
0.000
0.120
13.430
1.366
6000
Paved Medium Density Residential
1.245
0.000
0.120
13.430
1.840
7000
Paved High Density Residential
1.245
0.000
0.120
13.424
2.175
8000
Paved Transportation
1.245
0.000
0.120
9.661
1.391
9000
Paved Open Land
1.245
0.000
0.120
10.806
1.425
10110
Developed OpenSpace-A-Low
0.175
0.656
0.519
0.237
0.021
10120
Developed OpenSpace-A-Med
0.175
0.664
0.518
0.259
0.023
10210
Developed OpenSpace-B-Low
0.308
0.509
0.531
0.896
0.094
10220
Developed OpenSpace-B-Med
0.305
0.504
0.531
1.126
0.118
10310
Developed OpenSpace-C-Low
0.404
0.398
0.539
1.968
0.182
10320
Developed OpenSpace-C-Med
0.405
0.399
0.538
2.071
0.191
10410
Developed OpenSpace-D-Low
0.495
0.303
0.544
2.827
0.261
10420
Developed OpenSpace-D-Med
0.491
0.303
0.544
3.422
0.316
11000
Forested Wetland
0.264
0.107
0.994
0.418
0.087
12000
Non-Forested Wetland
0.263
0.105
0.992
0.414
0.086
13110
Forest-A-Low
0.058
0.537
0.776
0.100
0.020
13120
Forest-A-Med
0.057
0.535
0.775
0.105
0.021
13210
Forest-B-Low
0.132
0.446
0.787
0.452
0.089
13220
Forest-B-Med
0.131
0.444
0.787
0.476
0.094
13310
Forest-C-Low
0.204
0.363
0.793
0.908
0.168
13320
Forest-C-Med
0.203
0.362
0.793
0.963
0.178
38
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FDC 2A Project
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HRU
HRU Category
Runoff
(MG/ac/yr)
GW
(MG/ac/yr)
ET
(MG/ac/yr)
TN
(lb/ac/yr)
TP
(lb/ac/yr)
13410
Forest-D-Low
0.370
0.186
0.801
1.438
0.291
13420
Forest-D-Med
0.369
0.186
0.801
1.490
0.302
14110
Agriculture-A-Low
0.099
0.605
0.653
0.508
0.087
14120
Agriculture-A-Med
0.098
0.604
0.653
0.536
0.092
14210
Agriculture-B-Low
0.197
0.488
0.668
2.165
0.381
14220
Agriculture-B-Med
0.196
0.488
0.668
2.305
0.406
14310
Agriculture-C-Low
0.282
0.391
0.677
4.436
0.680
14320
Agriculture-C-Med
0.281
0.391
0.677
4.730
0.725
14410
Agriculture-D-Low
0.361
0.303
0.684
6.842
1.165
14420
Agriculture-D-Med
0.359
0.304
0.684
7.237
1.233
Units: MG - million gallons, lb - pounds, ac - acre, yr - year
Table 5-4. Summary of unit-acre-based annual average (Oct 2079 - Sep 2099) runoff volume, groundwater (GW)
recharge, evapotranspiration (ET), total nitrogen (TN) load, and total phosphorus (TP) load for the
modeled HRU types in the Wading River watershed (Ecodeficit 8.5 Median)
HRU
HRU Category
Runoff
(MG/ac/yr)
GW
(MG/ac/yr)
ET
(MG/ac/yr)
TN
(lb/ac/yr)
TP
(lb/ac/yr)
1000
Paved Forest
1.251
0.000
0.126
11.147
1.477
2000
Paved Agriculture
1.251
0.000
0.126
11.147
1.477
3000
Paved Commercial
1.251
0.000
0.126
14.805
1.691
4000
Paved Industrial
1.251
0.000
0.126
14.805
1.691
5000
Paved Low Density Residential
1.251
0.000
0.126
13.854
1.416
6000
Paved Medium Density Residential
1.251
0.000
0.126
13.854
1.906
7000
Paved High Density Residential
1.251
0.000
0.126
13.848
2.254
8000
Paved Transportation
1.251
0.000
0.126
9.966
1.442
9000
Paved Open Land
1.251
0.000
0.126
11.147
1.477
10110
Developed OpenSpace-A-Low
0.185
0.674
0.498
0.209
0.019
10120
Developed OpenSpace-A-Med
0.185
0.682
0.498
0.232
0.021
10210
Developed OpenSpace-B-Low
0.327
0.520
0.508
0.901
0.094
10220
Developed OpenSpace-B-Med
0.323
0.516
0.508
1.144
0.120
10310
Developed OpenSpace-C-Low
0.428
0.405
0.515
1.999
0.184
10320
Developed OpenSpace-C-Med
0.429
0.406
0.515
2.108
0.194
10410
Developed OpenSpace-D-Low
0.522
0.307
0.519
2.893
0.267
10420
Developed OpenSpace-D-Med
0.518
0.308
0.519
3.525
0.326
11000
Forested Wetland
0.293
0.119
0.960
0.442
0.092
12000
Non-Forested Wetland
0.292
0.117
0.957
0.439
0.092
13110
Forest-A-Low
0.062
0.572
0.743
0.089
0.018
13120
Forest-A-Med
0.062
0.570
0.743
0.093
0.018
13210
Forest-B-Low
0.144
0.474
0.753
0.460
0.091
13220
Forest-B-Med
0.143
0.473
0.753
0.490
0.097
39
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FDC 2A Project
Draft Project Report
HRU
HRU Category
Runoff
(MG/ac/yr)
GW
(MG/ac/yr)
ET
(MG/ac/yr)
TN
(lb/ac/yr)
TP
(lb/ac/yr)
13310
Forest-C-Low
0.224
0.385
0.758
0.977
0.181
13320
Forest-C-Med
0.223
0.384
0.758
1.035
0.192
13410
Forest-D-Low
0.401
0.198
0.765
1.504
0.305
13420
Forest-D-Med
0.399
0.197
0.765
1.558
0.315
14110
Agriculture-A-Low
0.106
0.628
0.630
0.431
0.074
14120
Agriculture-A-Med
0.106
0.627
0.630
0.458
0.079
14210
Agriculture-B-Low
0.214
0.503
0.644
2.267
0.399
14220
Agriculture-B-Med
0.213
0.503
0.644
2.426
0.427
14310
Agriculture-C-Low
0.305
0.402
0.651
4.658
0.714
14320
Agriculture-C-Med
0.303
0.402
0.651
4.966
0.761
14410
Agriculture-D-Low
0.388
0.312
0.657
7.102
1.210
14420
Agriculture-D-Med
0.386
0.312
0.657
7.502
1.278
Units: MG - million gallons, lb - pounds, ac - acre, yr - year
Table 5-5. Summary of unit-acre-based annual average (Oct 2079 - Sep 2099) runoff volume, groundwater (GW)
recharge, evapotranspiration (ET), total nitrogen (TN) load, and total phosphorus (TP) load for the
modeled HRU types in the Wading River watershed (Ecodeficit 8.5 Wet)
HRU
HRU Category
Runoff
(MG/ac/yr)
GW
(MG/ac/yr)
ET
(MG/ac/yr)
TN
(lb/ac/yr)
TP
(lb/ac/yr)
1000
Paved Forest
1.336
0.000
0.119
11.761
1.551
2000
Paved Agriculture
1.336
0.000
0.119
11.761
1.551
3000
Paved Commercial
1.336
0.000
0.119
15.623
1.777
4000
Paved Industrial
1.336
0.000
0.119
15.623
1.777
5000
Paved Low Density Residential
1.336
0.000
0.119
14.617
1.488
6000
Paved Medium Density Residential
1.336
0.000
0.119
14.617
2.056
7000
Paved High Density Residential
1.336
0.000
0.119
14.614
2.377
8000
Paved Transportation
1.336
0.000
0.119
10.517
1.514
9000
Paved Open Land
1.336
0.000
0.119
11.761
1.551
10110
Developed OpenSpace-A-Low
0.206
0.742
0.489
0.205
0.018
10120
Developed OpenSpace-A-Med
0.206
0.750
0.489
0.230
0.021
10210
Developed OpenSpace-B-Low
0.364
0.573
0.498
0.863
0.090
10220
Developed OpenSpace-B-Med
0.361
0.568
0.498
1.102
0.115
10310
Developed OpenSpace-C-Low
0.479
0.445
0.504
2.000
0.185
10320
Developed OpenSpace-C-Med
0.480
0.446
0.504
2.120
0.196
10410
Developed OpenSpace-D-Low
0.584
0.337
0.507
3.152
0.291
10420
Developed OpenSpace-D-Med
0.580
0.339
0.507
3.903
0.361
11000
Forested Wetland
0.368
0.147
0.939
0.575
0.120
12000
Non-Forested Wetland
0.367
0.146
0.936
0.573
0.119
13110
Forest-A-Low
0.079
0.640
0.740
0.092
0.018
13120
Forest-A-Med
0.079
0.638
0.740
0.097
0.019
40
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FDC 2A Project
Draft Project Report
HRU
HRU Category
Runoff
(MG/ac/yr)
GW
(MG/ac/yr)
ET
(MG/ac/yr)
TN
(lb/ac/yr)
TP
(lb/ac/yr)
13210
Forest-B-Low
0.177
0.531
0.747
0.463
0.092
13220
Forest-B-Med
0.176
0.529
0.747
0.493
0.098
13310
Forest-C-Low
0.271
0.428
0.751
1.031
0.191
13320
Forest-C-Med
0.270
0.427
0.751
1.101
0.204
13410
Forest-D-Low
0.478
0.216
0.755
1.788
0.362
13420
Forest-D-Med
0.476
0.215
0.755
1.859
0.376
14110
Agriculture-A-Low
0.126
0.699
0.618
0.426
0.073
14120
Agriculture-A-Med
0.126
0.698
0.618
0.453
0.078
14210
Agriculture-B-Low
0.250
0.561
0.630
2.231
0.393
14220
Agriculture-B-Med
0.249
0.561
0.630
2.387
0.420
14310
Agriculture-C-Low
0.356
0.447
0.636
4.805
0.737
14320
Agriculture-C-Med
0.355
0.447
0.636
5.161
0.791
14410
Agriculture-D-Low
0.452
0.344
0.641
7.890
1.344
14420
Agriculture-D-Med
0.450
0.344
0.641
8.395
1.430
Units: MG - million gallons, lb - pounds, ac - acre, yr - year
The unit-acre unattenuated values were applied to the baseline and future development HRU areas to
estimate the net change in hydrology and water quality for the Taunton River watershed. As expected, with
the same historic climate data and increased IC from the 2060 land use, runoff and pollutant loads increased,
while groundwater recharge and evapotranspiration decreased (Figure 5-1, blue). The selected future climate
scenarios had increased precipitation and temperature compared to the baseline. Of the future scenarios, the
2060 land use Ecodeficit 8.5 Dry combination had the smallest change in the runoff, TN, and TP compared
to the 2016 baseline with historic climate, but the greatest decrease in groundwater recharge (Figure 5-1,
orange). While the Ecodeficit 8.5 Dry scenario has a 5% increase in annual average precipitation, it also has
a 16% increase in annual average temperature (Figure 4-1). The increase in temperature increased ET by
18MG/yr compared to the 2016 baseline with historic climate and drove the reduced runoff and
groundwater recharge, and subsequently the lower changes in TN and TP. At the other extreme, the
Ecodeficit 8.5 Wet scenario had the greatest changes in runoff, groundwater recharge, and TN (Figure 5-1,
red). The 8% increase in temperature for this scenario did lead to a lower reduction in ET compared to the
2060 land use-historic climate scenario, however, the 10% increase in precipitation still drove the increases
in the other parameters. Results for the Ecodeficit 8.5 Median climate scenario fell between the Wet and
Dry extremes with a consistent pattern across all of the parameters (Figure 5-1, green).
The trends seen at the Taunton River watershed scale are also reflected at the municipality level (annual
average runoff and loadings and the change between baseline and future conditions by the municipality are
shown in Appendix A (Table 3 through Table 11). As an example (Table 8 in Appendix A), IC in the
Taunton Municipality increased by nearly 3,000 acres. This led to an increase in runoff of nearly 3,600
million gallons/year and an additional 38,000 pounds and 4,500 pounds of TN and TP per year on average
for the 2060 land use-historic climate scenario. Correspondingly, groundwater recharge and
evapotranspiration decreased by 1,300 and 2,300 million gallons/year.
41
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FDC 2A Project
Draft Project Report
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2060
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-------
FDC 2A Project
Draft Project Report
of TN and 1.5 large dump trucks of TP as the average annual increase in nutrients load in the entire Taunton
River watershed.
Table 5-6. Summary of change in major land use area distribution between 2016 baseline and 2060 future conditions
in the Taunton River watershed
Major Land Use Classification
Land Cover
2016 Baseline
(acre)
2060 Future
(acre)
Change (%)
Paved Forest
Impervious
9
9
0%
Paved Agriculture
Impervious 128
158
23%
Paved Commercial
Impervious 4,858
6,873
41%
Paved Industrial
Impervious 2,745
3,892
42%
Paved Low Density Residential
Impervious 9,951
20,717
108%
Paved Medium Density Residential
Impervious 489
1,133
132%
Paved High Density Residential
Impervious 2,856
4,041
42%
Paved Transportation
Impervious 11,852
21,709
83%
Paved Open Land
Impervious 4,138
8,377
102%
Developed OpenSpace
Pervious 40,955
76,120
86%
Forested Wetland
Pervious 66,463
66,463
0%
Non-Forested Wetland
Pervious 9,734
9,734
0%
Forest
Pervious 144,393
78,832
-45%
Agriculture
Pervious 25,255
25,768
2%
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Table 5-7. Summary of changes between baseline land use and historic climate model results and the future land use and climate scenarios for annual average
runoff volume, groundwater (GW) recharge, evapotranspiration (ET), total nitrogen (TN) load, and total phosphorus (TP) load by major land use in
Taunton River watershed
Runoff (MG/yr)
GW Recharge (MG/yr)
ET (MG/yr)
TN (Ib/yr)
TP (Ib/yr)
Classification
2060
FLULC
Ecodef.
8.5 Dry
Ecodef.
8.5 Med.
Ecodef.
8.5 Wet
2060
FLULC
Ecodef.
8.5 Dry
Ecodef.
8.5 Med.
Ecodef.
8.5 Wet
2060
FLULC
Ecodef.
8.5 Dry
Ecodef.
8.5 Med.
Ecodef.
8.5 Wet
2060
FLULC
Ecodef.
8.5 Dry
Ecodef.
8.5 Med.
Ecodef.
8.5 Wet
2060
FLULC
Ecodef.
8.5 Dry
Ecodef.
8.5 Med.
Ecodef.
8.5 Wet
Paved Forest
0
0
0
1
0
0
0
0
0
0
0
0
0
-6
-3
3
0
-1
0
0
Paved
Agriculture
36
38
39
53
0
0
0
0
4
3
4
3
339
233
287
384
44
32
40
52
Paved
Commercial
2,486
2,559
2,601
3,185
0
0
0
0
254
212
256
202
30,707
24,599
27,714
33,340
3,615
2,494
2,905
3,495
Paved
Industrial
1,416
1,457
1,480
1,811
0
0
0
0
145
121
146
115
17,484
14,025
15,789
18,975
2,058
1,424
1,656
1,990
Paved Low
Density
Residential
13,285
13,503
13,630
15,390
0
0
0
0
1,357
1,230
1,364
1,201
153,634
136,222
145,011
160,824
16,182
13,352
14,390
15,878
Paved Medium
Density
Residential
795
807
814
910
0
0
0
0
81
74
82
73
9,192
8,239
8,720
9,585
1,269
1,122
1,196
1,367
Paved High
Density
Residential
1,463
1,505
1,530
1,874
0
0
0
0
149
125
151
119
16,905
13,528
15,241
18,335
2,823
1,992
2,311
2,807
Paved
Transportation
12,164
12,392
12,525
14,369
0
0
0
0
1,242
1,110
1,250
1,079
101,133
88,134
94,758
106,720
15,101
12,042
13,152
14,720
Paved Open
Land
5,231
5,319
5,370
6,080
0
0
0
0
534
483
537
471
48,661
43,020
45,875
51,011
6,646
5,447
5,884
6,506
Developed
OpenSpace
14,083
8,832
10,186
13,169
17,380
16,647
17,524
21,417
16,308
21,417
19,698
18,925
59,202
44,899
45,999
51,368
5,516
4,203
4,309
4,801
Forested
Wetland
0
-4,420
-2,529
2,444
0
-3,463
-2,631
-767
0
7,816
5,554
4,199
0
-6,797
-5,163
3,631
0
-1,459
-1,118
715
Non-Forested
Wetland
0
-683
-403
330
0
-540
-418
-141
0
1,145
810
602
0
-1,027
-785
511
0
-220
-170
100
Forest
-15,491
-19,672
-18,225
-14,457
-29,320
-33,833
-32,054
-28,694
-44,636
-36,120
-38,835
-39,411
-56,406
-70,920
-68,137
-58,062
-11,193
-14,100
-13,549
-11,522
Agriculture
174
-1,287
-785
416
220
-707
-355
891
304
2,402
1,738
1,374
2,916
-14,091
-10,533
-301
485
-2,386
-1,791
-58
TOTAL
35,642
20,349
26,233
45,576
-11,720
-21,895
-17,933
-7,295
-24,259
18
-7,245
-11,046
383,765
280,057
314,774
396,321
42,545
23,943
29,216
40,850
Units: MG - million gallons, lb - pounds, yr - year
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6. IMPACTS OF FUTURE LAND USE AND CLIMATE ON THE
UPPER HODGES BROOK SUBWATERSHED
The preceding sections described projections of future land use and climate for the Taunton River watershed
as a whole; much of the remainder of this report focuses on the impact of next-generation SCMs on second
and third-order headwater stream segments and finer scales. The Upper Hodges Brook subwatershed, which
is a tributary to the Wading river within the Taunton River watershed, was used as a pilot for this purpose.
Table 6-1 shows a 34% increase in impervious cover and a 55% increase in developed pervious cover
resulting from a 67% decrease in the forested land cover for 2060 future land use/land cover in the pilot
subwatershed. As such, the impacts of future land use, climate, and IC disconnection were evaluated for
Upper Hodges Brook and are presented in this section.
Table 6-1. Summary of changes in the land cover area between baseline land cover and the future land cover in Upper
Hodges Brook sub-watershed
Land Cover Class
2016 Existing Area
2060 Future Area
Change in Area
Acres
%
Acres
%
Acres
%
Impervious
424.1
32%
567.6
42%
143.5
34%
Developed Pervious
273.7
20%
422.9
32%
149.2
55%
Forest
461.5
35%
153.8
11%
-307.7
-67%
Agriculture
17.8
1%
32.8
2%
15.0
84%
Water/Wetland
160.2
12%
160.2
12%
0.0
0%
Total
1,337.3
100%
1,337.3
100%
-
-
When future land use is simulated in the Upper Hodges Brook subwatershed with historic climate
conditions, there is a moderate increase in flow across the entire FDC (Figure 6-1). When future IC is fully
connected (100% unmanaged), high flows are increased and low flows are decreased compared to the
existing IC and predevelopment conditions. This is because of increase in IC generates more runoff causing
an increase in the high flows and loss of vegetated cover causes less infiltration and evapotranspiration
resulting in a decrease in low flows. Conversely, when IC is fully disconnected (100% managed), the highest
10% of flows are less than existing conditions, and moderate to low flows are greater. This is because
capturing all runoff from IC under a 100% managed scenario brings down the high flows but due to loss in
vegetated areas the ET is significantly reduced and higher infiltrated water causes an increase in the baseflow.
Impacts from the combination of future land use and future climate scenarios on the Upper Hodges Brook
are generally consistent with those for the larger Taunton River watershed. These are key points for
comparing baseline scenarios against future land use scenarios under various climatic conditions.
• The historic climate scenario for future land use conditions generates more flow across the entire
FDC by comparing against the baseline scenario. This reflects the increased IC at the expense of
natural vegetated cover, which increases runoff primarily by decreasing evapotranspiration and
creates an ecosurplus of 90 MG/yr (Figure 6-2).
• The dry future climate scenario for future land use conditions creates ecodeficit across all but the
highest 10% of flows. It creates an ecosurplus of 66.9 MG/yr and an ecodeficit of 90.5 MG/yr
(Figure 6-3).
• The median future climate scenario for future land use conditions shows slightly higher ecosurplus
(79.9 MG/yr) and lower ecodeficit (68.2 MG/yr) patterns as compared to the dry future climate
scenario (Figure 6-4).
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• The wet future climate scenario for future land use conditions shows similar trends with higher
ecosurplus (182.4 MG/yr) and lower ecodeficit (55.9 MG/yr) patterns as compared to the median
future climate scenario (Figure 6-5).
Figure 6-6 shows the impacts of various climatic conditions on hydrology and water quality between the
baseline scenario and future land use scenario in the pilot sub-watershed. The trend is consistent across three
future climate conditions. There is an increasing trend in runoff and nutrient loads for the dry, median, and
wet future climate conditions, respectively.
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FDC 2A Project
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10
20
30 40 50 60
Percent of time discharge was equaled or exceeded
70
80
90
100
Figure 6-1. Flow duration curves for the Upper Hodges Brook for predeveiopment, baseline (2016 existing conditions), and future land use/land cover (FLULC) with
varying amounts of IC disconnection {existing condition, fully connected (EIA=TIA), and fully disconnected (EIA=0)). All scenarios use historic climate
data.
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FDC 2A Project
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Baseline
2060 FLULC,
Historic Climate
I Overland Flow (MG/yr)
Interflow (MG/yr)
Groundwater (MG/yr)
Evapotranspiration (MG/yr)
I Ecodeficit: 0.0 cfs/day (0.0 MG/year)
i Ecosurplus: 0.4 cfs/day (90.0 MG/year)
1000
100
10
0.1
0.01
— Baseline/Existing Conditions
— — 2060 Land Use, Historic Climate
O
5?
o
c:5
O
£
o
cN
O
VD
K
o
*
o
00
£
o
cr>
Percent of time discharge was equaled or exceeded
Figure 6-2. Water balance (pie charts) and FDC comparisons for existing baseline conditions and future land use with
the historic climate scenario for the Upper Hodges Brook subwatershed.
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Baseline
2060 FLULC,
Ecodeficit 8.5 Dry
i Overland Flow (MG/yr)
Interflow (MG/yr)
Groundwater (MG/yr)
Evapotranspiration (MG/yr)
xooo
100
10
0.1
o.oi
^¦i Ecodeficit: 0.4 cfs/day (90.5 MG/year)
Baseline/Existing Conditions
Ecosurplus: 0.3 cfs/day (66.9 MG/year)
— — miroc-esm-1 - RCP 8.5 Dry
5?
O
o
o
o
$
o
SS
o
o
o
00
SS
o
en
Percent of time discharge was equaled or exceeded
Figure 6-3. Water balance (pie charts) and FDC comparisons for existing baseline conditions and future land use with
the dry future climate scenario for the Upper Hodges Brook subwatershed.
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FDC 2A Project
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Baseline
¦ Overland Flow (MG/yr)
¦ Interflow (MG/yr)
¦ Groundwater (MG/yr)
¦ Evapotranspiration (MG/yr)
2060 FLULC,
Ecodeficit 8.5 Median
M
IV
¦C
1000
100
10
0.1
0.01
>5
o
: Ecodeficit: 0.3 cfs/day (68.2 MG/year)
I Ecosurplus: 0.3 cfs/day (79.9 MG/year)
Baseline/Existing Conditions
cesml-cam5-:
1-RCP8.5-
Median
"""" ~ ~ —
~~ — — „
l
O
£
o
£
o
5?
o
<3-
•P
O
= -
O
£
o
:-r
o
00
o
Percent of time discharge was equaled or exceeded
Figure 6-4. Water balance (pie charts) and FDC comparisons for existing baseline conditions and future land use with
the median future climate scenario for the Upper Hodges Brook subwatershed.
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FDC 2A Project
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Baseline
2060 FLULC,
Ecodeficit 8.5 Wet
¦ Overland Flow (MG/yr)
¦ Interflow (MG/yr)
Groundwater (MG/yr)
¦ Evapotranspiration (MG/yr)
1000
100
10
MM Ecodeficit: 0.2 cfs/day (55.9 MG/year)
Baseline/Existing Conditions
Ecosurplus: 0.8 cfs/day (182.4 MG/year)
— — mri-cgcm3-l - RCP8.5 - Wet
0.1
0.01
1
O
6?
O
c<
o
*
o
*
o
3?
o
*
o
£
o
---?
o
00
O
Percent of time discharge was equaled or exceeded
Figure 6-5. Water balance (pie charts) arid FDC comparisons for existing baseline conditions and future land use with
the wet future climate scenario for the Upper Hodges Brook subwatershed.
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100
> 50
en
-50
>0 -
JL
1000
800
- 600
r
u
- 400 --
- 200
0
Runoff GW ET TN TP
2060 Landuse, Historic Climate - 2016 Baseline Condition, Historic Climate
2060 Landuse, Ecodeficit 8.5 Dry - 2016 Baseline Condition, Historic Climate
2060 Landuse, Ecodeficit 8.5 Median - 2016 Baseline Condition, Historic Climate
2060 Landuse, Ecodeficit 8.5 Wet - 2016 Baseline Condition, Historic Climate
Figure 6-6. Comparison of changes in hydrology (runoff, groundwater recharge GW, and evapotranspiration ET) and
water quality parameters (total nitrogen TN and total phosphorous TP) between the baseline and future
land use/climate conditions for the Upper Hodges Brook subwatershed.
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7. SITE SCALE MODELING ANALYSES
This section shows the modeling analysis of 12 scenarios for 3 site-scale concept designs which were taken
from the real-world site plans to demonstrate the effectiveness of green infrastructure stormwater control
measures (GI SCMs) that meet the existing standard of the Massachusetts Department of Environmental
Protection (MassDEP) and also include a more protective high level of controls that nearly return the
predevelopment hydrology. These site-scale conceptual designs were created for nD/rD scenarios. Each of
these scenarios was configured in the Opti-Tool and the results are analyzed under the following sub-
sections. Some of the CD practices were added to the Opti-Tool to simulate those GI SCMs under the site-
scale and watershed-scale modeling scenarios. Appendix B outlines four new GI SCM, incorporated into
the Opti-Tool to support management alternative analyses involving disconnection of impervious cover.
7.1. Site Scale Modeling Scenarios
Table 7-1 lists the site scale modeling scenarios; these are further distinguished by the level of stormwater
control. Scenarios 1.2, 2.2, and 3.2 are developed sites with no SCMs. Scenarios 1.3, 2.3, and 3.3 represent
current MassDEP and MS4 standards with peak flow control. Scenarios 1.4, 2.4, and 3.4 represent next-
generation SCMs that promote resilient hydrology similar to predevelopment conditions with no net increase
in nutrient loads. These scenarios were tested with both historic and future climate conditions.
Table 7-1. Conceptual design scenarios
Concept
Design
Site Type
HSG
Scenario
Control Level
1
High Density Residential
C
1.1
Predevelopment
1.2
No Controls
1.3
Conventional
1.4
GI and CD Practices
2
High Density Commercial
A
2.1
Predevelopment
2.2
No Controls
2.3
Conventional
2.4
GI and CD Practices
3
Low Density Residential
B
3.1
Predevelopment
3.2
No Controls
3.3
Conventional
3.4
GI and CD Practices
Conceptual Design 1 represents the new development of a high-density residential site. In Scenario 1.3, each
single-family home has a rain garden that treats driveway runoff and an infiltration trench that treats rooftop
runoff (Figure 7-1). These SCMs, and road runoff, all drain into a detention pond. In comparison, Scenario
1.4 treats road and roof runoff with infiltration trenches sized for enhanced capture; rooftop infiltration
trenches drain into the roadway infiltration system (Figure 7-2). This eliminates the need for a detention
pond and allows an additional house to be built.
The new development of a high-density commercial site is represented in Conceptual Design 2. In Scenario
2.3, infiltration trenches treat rooftop runoff from one building and drain to subsurface detention (pipe
storage) below a parking lot (Figure 7-3). Runoff from another rooftop is treated by permeable pavement. In
Scenario 2.4, the subsurface detention is replaced with permeable pavement for the entire parking lot (Figure
7-4).
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Conceptual Design 3 represents the new development of a low-density residential area with dispersed
housing units and large meadow and forest buffers. Runoff from rooftops, driveways, and roads is treated
by routing it via sheet flow over buffer areas (i.e., IC disconnection). This allows for runoff reduction by
infiltration and evapotranspiration, sediment capture based on the vegetated land cover, and nutrient uptake
by vegetation. Scenario 3.4 provides enhanced treatment by first treating runoff from impervious surfaces
through infiltration trenches that infiltrate and act as level spreaders to pervious areas when their capacity is
exceeded.
7.2. Site Scale Opti-Tool Setup
The setup of site scale conceptual designs began by transferring site information (e.g., land use, soil type)
and SCM information (e.g., type, sizing, drainage area) into the Opti-Tool. One Opti-Tool model was
created for each conceptual design and scenario; Figure 7-1 to Figure 7-4 show the Opti-Tool watershed
sketch for Scenarios 1.3, 1.4, 2.3, and 2.4, respectively. The drainage area and footprints for SCMs used in
each scenario are shown in Table 7-2 and Table 7-3, respectively. SCM specifications used in concept designs
1, 2, and 3 are given in Table 7-4, Table 7-5, and Table 7-5, respectively.
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Specif?' Watershed Information
1 LomnVfler"Jii | optional)
d
1 Watfnlwdlflfcrnirticu
J Landlh* Ia&nnahco
4 Poflnian! Dfiitincw;
f Aanffcr lifctnwxu
_Sketch and Model Setup
Step 6. Add Subwatershed/Junctions
Step 7. AddBMPs
Step 8. Add Stream/Conduits (optional)
o Optmnifltiai Strap
10 Crerte hput File and Run
Re vet All Information
Return to Hod* Pase
Number of Subwatersheds: 1
Number of Landuses: 38
Number of BMPs: 13
Number of Pollutants: 5
Number of Aquifers: 1
Ram Garden
Detention Pood
Figure 7-1. Opti-Tool watershed sketch for Scenario 1.3 with conceptual SCM diagrams.
Detention Pond
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FDC 2A Project
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1 LoadW«*rJisdU9B,'CDHaoflll
Step 8. Add Subwatershed/Junctions
Step 7. Add BMPs
p 8. Add Stream/Conduits (optional)
9 Optitnunhai Setup
Number of Subwatersheds: 1
Number of Landuses: 36
Number of BMPs: 8
Number of Pollutants: 5
Number of Aquifers: 1
Sketch and Model Setup
BMP & Stream Network Sketc hD..
Garden
infiltration Trench
Rooftop Downspout
and infiltration Trench
Figure 7-2. Opti-Tool watershed sketch for Scenario 1.4 with conceptual SCM diagrams.
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Specify Watershed Information
1 LoodWnle rJxed Map (optional)
J
2. Water-lie dlafcrnmriau
J. LmdVie In&rmaaon
4 Pollutant Defnitinr.
? Aquiier hiautttuta
Sketch and Model Setup
Step 6. Add Subwatershed/Junctions
Step 7. Add BMPs
Step 8. Add Stream/Conduits (optional)
N.
9 Optimu nbai S etnp
10 Create hpntFile and Run
Re set All Information
Return to Home Pase
Number of Subwatersheds: 1
Number of Landuses: 36
Number of BMPs: 4
Number of Pollutants: 5
Number of Aquifers: 1
BMP AJitream.N'emork Sketch Design
5TRM 1 Junctionl
Figure 7-3. Opti-Tool watershed sketch for Scenario 2.3 with conceptual SCM diagrams.
Drip Edge Infiltration
Trench and Walkway
UMfW *
J I /
itlon f
il#ui t. r.ii
H
W
Subsurface Detention
Rooftop Downspout and Permeable Pavers
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_S£ecif£jjVatershedlnformation_
1. Lend Wne rrliwl ilnp (optional)
J
BMP & Stream Network Sketch Design
3 Laodl?^ IafirmailoD
4 PoEutrmt D* initial-.
5 Aqmfer fafbrmatioa
Sketch and Model Setup
Step 6. Add Subwatershed/Junctions
Step 8. Add Stream/Conduits (optional)
N.
9 Optmm.irion Setup
10 Create hputFil* and Run
Re set .All Infbrmaticu
Return to Heme Pee*
Number of Subwatersheds: 1
Number of Landuses: 36
Number of BMPs: 4
Number of Pollutants: 5
Number of Aquifers: 1
Figure 7-4. Opti-Tool watershed sketch for Scenario 2.4 with conceptual SCM diagrams.
STRM.l Junction 1
BVIP4
Drip Edge Infiltration
Trench and Walkway
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Table 7-2. SCM drainage areas (acres) for the concept designs 1, 2, and 3
Residential
Transportation
Open Land
Developed Open
Space
.4 2.3 2.4 3.3
Rooftop
Infiltration Trench
A
0.17
0.17
Porous Pavement
A
0.10
0.06
Other IC
Porous Pavement
A
0.22
Bioretention
A
0.18
Rooftop
Infiltration Trench
B
0.92
IC Disconnection
B
0.92
Rooftop
Infiltration Trench
C
0.36
0.41
Bioretention
C
0.12
Other IC
Infiltration trench
C
0.14
Infiltration trench
C (1.4)
B (3.4)
0.12
0.24
Other IC
Bioretention
C
0.12
IC Disconnection
B
0.24
Other IC
Infiltration trench
C
0.66
Bioretention
C
0.97
NA
IC Disconnection
B
7.15
7.15
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Table 7-3. SCM capacity (ft3) for the concept designs 1,2, and 3
H KilllJl K11 roil
Open Land
Developed Open
Space
.4 2.3
Rooftop
Infiltration
Trench
A
1,245
1,423
Porous Pavement
A
1,244
566
Other IC
Porous Pavement
A
12,019
Bioretention
A
1,698
Rooftop
Infiltration
Trench
B
34,911
IC Disconnection
B
Rooftop
Infiltration
Trench
C
1,508
1,471
Bioretention
C
840
Other IC
Infiltration trench
C
4,689
Infiltration trench
C
4,004
Other IC
Bioretention
C
429
IC Disconnection
B
Other IC
Infiltration trench
C
2,008
Bioretention
C
NA
IC Disconnection
B
47,021
47,021
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Table 7-4. SCM design specifications for conceptual design 1
General
Information
SCM
Parameters
Infiltration Trench
HSG-C
Bioretention
(Rain Garden)
HSG-C
Bioretention
(Detention Pond)
HSG-C
Infiltration Trench
(Roadway
Subsurface) HSG - C
Surface
Storage
Configuration
Orifice Height
(ft)
0
0
0
0
Orifice
Diameter (in.)
0
0
0.75
0
Rectangular or
Triangular
Weir
Rectangular
Rectangular
Rectangular
Rectangular
Weir Height
(ft)/Ponding
Depth (ft)
0
0.5
4
0
Crest Width
(ft)
30
30
30
30
Soil Properties
Depth of Soil
(ft)
3
2
0
2.5
Soil Porosity
(0-1)
0.4
0.25
0.4
0.4
Vegetative
Parameter A
0.9
0.9
0
0.9
Soil Infiltration
(in/hr)
0.27
0.27
0
0.27
Underdrain
Properties
Consider
Underdrain
Structure?
No
No
No
No
Storage Depth
(ft)
0
0
0
0
Media Void
Fraction (0-1)
0
0
0
0
Background
Infiltration
(in/hr)
N/A
N/A
N/A
N/A
Cost
Parameters
(CD1.4)
Storage
Volume Cost
($/ft3)
$12.82 ($10.53)
$6.35
$6.98
$5.51
Cost Function
Adjustment
(CD1.4)
SCM
Development
Type
New SCM in
Undeveloped
Area
New SCM in
Undeveloped
Area
New SCM in
Undeveloped
Area
New SCM in
Undeveloped Area
Cost
Adjustment
Factor
1 (0.8215)
0.4
0.44
0.43
Decay Rates
TSS (1/hr)
0.74
0.79
0.79
0.74
61
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General
Information
SCM
Parameters
Infiltration Trench
HSG-C
Bioretention
(Rain Garden)
HSG-C
Bioretention
(Detention Pond)
HSG-C
Infiltration Trench
(Roadway
Subsurface) HSG - C
TN (1/hr)
0.42
0.01
0.01
0.42
TP (1/hr)
0.03
0.01
0.01
0.03
1 ZN (1/hr)
0.45
0.49
0.49
0.45
Underdrain
Removal Rates
TSS (%, 0-1)
N/A
N/A
N/A
N/A
TN (%, 0-1)
N/A
N/A
N/A
N/A
TP (%, 0-1)
N/A
N/A
N/A
N/A
ZN (%, 0-1)
N/A
N/A
N/A
N/A
Table 7-5. SCM design specifications for conceptual design 2
General
Information
SCM
Parameters
Infiltration Trench
HSG-A
Porous
Pavement
(Concrete) HSG A
Porous Pavement
(Asphalt) HSG A
Bioretention
(Subsurface
Detention) HSG A
Orifice
Height (ft)
0
0
0
0
Orifice
Diameter
(in.)
0
0
0
1
Surface
Storage
Configuration
Rectangular
orTriangular
Weir
Rectangular
Rectangular
Rectangular
Rectangular
Weir Height
(ft)/Ponding
Depth (ft)
0
0
0
3.5
Crest Width
(ft)
30
30
30
30
Depth of Soil
(ft)
1.75 (2)
1.1(0.5)
1.75
0
Soil
Soil Porosity
(0-1)
0.4
0.4
0.4
0.4
Properties
(CD2.4)
Vegetative
Parameter A
0.9
0.1
0.1
0.9
Soil
Infiltration
(in/hr)
2.41
2.41
2.41
0
Consider
Underdrain
Structure?
No
No
No
No
Underdrain
Properties
Storage
Depth (ft)
0
0
0
0
Media Void
Fraction (0-1)
0
0
0
0
62
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FDC 2A Project
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General
Information
SCM
Parameters
Infiltration Trench
HSG-A
Porous
Pavement
(Concrete) HSG A
Porous Pavement
(Asphalt) HSG A
Bioretention
(Subsurface
Detention) HSG A
Background
Infiltration
(in/hr)
N/A
N/A
N/A
N/A
Cost
Parameters
Storage
Volume Cost
($/ft3)
$12.82
$18.07
$5.46
$15.87
Cost Function
Adjustment
SCM
Development
Type
New SCM in
Undeveloped
Area
New SCM in
Undeveloped
Area
New SCM in
Undeveloped Area
New SCM in
Undeveloped Area
Cost
Adjustment
Factor
1
1
1
1
Decay Rates
TSS (1/hr)
0.74
0.22
0.22
0.79
TN (1/hr)
0.42
0.26
0.26
0.01
TP (1/hr)
0.03
0.0051
0.0051
0.01
ZN (1/hr)
0.45
0.14
0.14
0.49
Underdrain
Removal
Rates
TSS (%, 0-1)
N/A
N/A
N/A
N/A
TN (%, 0-1)
N/A
N/A
N/A
N/A
TP (%, 0-1)
N/A
N/A
N/A
N/A
ZN (%, 0-1)
N/A
N/A
N/A
N/A
Table 7-6. SCM design specifications for conceptual design 3
General Information
SCM Parameters
Infiltration Trench HSG - B
IC Disconnection HSG - B
Surface Storage
Configuration
Orifice Height (ft)
0
0
Orifice Diameter (in.)
0
0
Rectangular or Triangular Weir
Rectangular
Rectangular
Weir Height (ft)/Ponding Depth (ft)
0.5
0.15
Crest Width (ft)
30
0
Pervious Area
Properties
Depression Storage (in.)
N/A
0.15
Slope
N/A
0.19
Mannings n
N/A
0.12 (meadow), 0.05
(forest)
Soil Properties
Depth of Soil (ft)
4
0
63
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FDC 2A Project
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General Information
SCM Parameters
Infiltration Trench HSG - B
IC Disconnection HSG - B
Soil Porosity (0-1)
0.4
0.3
Vegetative Parameter A
0.9
0.9
Soil Infiltration (in/hr)
1.5
0.1
Underdrain
Properties
Consider Underdrain Structure?
No
No
Storage Depth (ft)
0
0
Media Void Fraction (0-1)
0
0
Background Infiltration (in/hr)
N/A
N/A
Cost Parameters
Storage Volume Cost ($/ft3)
$12.82
$0.00
Cost Function
Adjustment
SCM Development Type
New SCM in Undeveloped
Area
New SCM in Undeveloped
Area
Cost Adjustment Factor
1
1
Decay Rates
TSS (1/hr)
0.74
0.2
TN (1/hr)
0.42
0.2
TP (1/hr)
0.03
0.2
ZN (1/hr)
0.45
0.2
Underdrain Removal
Rates
TSS (%, 0-1)
N/A
N/A
TN (%, 0-1)
N/A
N/A
TP (%, 0-1)
N/A
N/A
ZN (%, 0-1)
N/A
N/A
64
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FDC 2A Project
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7.3. Site Scale Modeling Results
Runoff duration curves (RDCs), which account for storm runoff only, are conceptually similar to FDCs and
provide a powerful tool to illustrate the differences between the control levels for each conceptual design.
Each of the RDCs in Figure 7-5 to Figure 7-10 shows predevelopment hydrology ("Pre-Dev"), no controls
developed under historical climate conditions ("Post-Dev, no BMPs"), the controlled developed under
historical climate conditions ("Post-Dev, with BMPs"), and the controlled developed under future climate
conditions ("Future Climate, with BMPs"). Comparing scenarios 1.3 and 1.4, it is clear that the SCMs in
scenario 1.4 are a much better match to predevelopment hydrology for the high density residential site.
Similarly, scenario 2.4 achieves near-predevelopment hydrology across the entire runoff duration curve. An
example of what a large event on the upper end of the RDC looks like is shown in Figure 7-11 and Figure
7-12. For this 10-year, 24-hour storm event (totaling 4.9 in of rainfall in 24 hours) from the historical
precipitation record, the GI and CD practices eliminated peak flow and attenuated the entire event.
The RDCs for the median future climate ("Future Climate, with BMPs") as compared to the RDCs for
historic precipitation ("Post-Dev, with BMPs"), show all flows are shifted somewhat higher, reflecting the
increase in precipitation. Even with the increased precipitation, the GI and CD practices like those used in
scenario 2.4 are effective at approaching predevelopment hydrology.
Annualized runoff, TSS, and TP loads for each conceptual design are shown in Figure 7-13 to Figure 7-15
for both historic and median future climate conditions. For each conceptual design, the GI and CD practices
outperform conventional and no control scenarios. The capital cost and the cost per acre IC treated for each
scenario are shown in Table 7-7. Further, while pollutant loads from the GI and CD practices are greatly
reduced for the high-density residential site compared to conventional practices, they are almost eliminated
for the commercial site. IC disconnection for the low-density residential site is a particularly effective SCM,
with or without the infiltration trenches used in scenario 3.4. Infiltration trenches would be needed to meet
the peak flow standard as shown in Figure 7-12.
Table 7-7. Summary of total cost and cost of unit-acre IC treated for each scenario at site-scale concept plans
Concept
Design
Site Type
HSG
Scenario
Control Level
Total Cost ($)
Cost/Acre IC
Treated ($)
1.1
Predevelopment
-
-
1
High Density
C
1.2
No Controls
-
-
Residential
1.3
Conventional
$37,804
$63,536
1.4
GI and CD Practices
$33,843
$50,815
2.1
Predevelopment
-
-
2
High Density
A
2.2
No Controls
-
-
Commercial
2.3
Conventional
$42,337
$93,459
2.4
GI and CD Practices
$37,678
$83,173
3.1
Predevelopment
-
-
3
Low Density
B
3.2
No Controls
-
-
Residential
3.3
Conventional
$0*
$0*
3.4
GI and CD Practices
$208,861
$180,052
*The cost of disconnecting the IC and level spreader to route the flow to the buffer area is not considered.
65
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FDC 2A Project
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Post-Dev, no BMPs Post-Dev, with BMPs Future Climate, with BMPs Pre-Dev
1
Flow-Exceedance Percentiles (Wet Days Only)
0.001
0.001
15%
Figure 7-5. Runoff duration curve for CD1.3 with historic and future climate,
Post-Dev, no BMPs Post-Dev, with BMPs Future Climate, with BMPs Pre-Dev
Figure 7-6. Runoff duration curve for CD1.4 with historic and future climate.
0.001
s? s?
o m
\0 \0 \0 N.O \0 \0 \0 \0 \P S.O sP \o
OS ON. 0s* ON 0s" 0s* ON ffS ON ON ffS
LnOLOOLOOLOOLDOLnO
m^^tLnLouD^Dr^r^ooooa»
Flow-Exceedance Percentiles (Wet Days Only)
66
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FDC 2A Project
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-Post-Dev, rio BMPs
¦Post-Dev, with BMPs Future Climate, with BMPs Pre-Dev
to
it
o
c
3
cc
£
o
¦M
to
0.1
0.01
0.001
\p so sp
cN oN ON ON
LO O LO O
(N rsi m
^ ^ ^ ^
O LO O LO
CO 00 CTi CT>
Flow-Exceedance Percentiles (Wet Days Only)
Figure 7-7. Runoff duration curve for CD2.3 with historic and future climate.
•Post-Dev, no BMPs
• Post-Dev, with BMPs Future Climate, with BMPs
Pre-Dev
*4—
U
!t
o
c
3
DC
E
o
4->
to
0.1
0.01
NO
ON
NP
ON
NO
ON
NP
ON
\p
ON
sP
ON
Np
ON
NP
©**•
NP
ON
NP
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\P
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NO
ON
no
ON
NP
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nP
ON
NP
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nP
on
NP
ON
NP
ON
NP
ON
NP
on
o
LO
O
LO
O
LO
O
LO
o
LO
o
LO
O
LO
o
LO
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LO
o
LO
O
*—1
rsi
("NJ
m
m
LO
LO
LD
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r-
00
oo
en
o
0.001
\P \0 sP nP nP \0 \0
ON ON ON ON ON 0s- ON
O LD O LO O LO O
rH r\i rsi m
Flow-Exceedance Percentiles (Wet Days Only)
Figure 7-8. Runoff duration curve for CD2.4 with historic and future climate.
67
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FDC 2A Project
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Post-Dev, no BMPs Post-Dev, with BMPs Future Climate, with BMPs Pre-Dev
Figure 7-9. Runoff duration curve for CD3.3 with historic and future climate.
\0 \0 \0 vO \0 \0 \0 \0 sP \0 Vp \0
o^ os OS OS ON os o^ OS ON ON OS o^
OLOOLDOLnoLOOLnOLn
roro^-^-mLnix>^Dr^r^oooo
Flow-Exceedance Percentiles (Wet Days Only)
0.001
10
to
n-
u
it
O
c
3
DC
0.1
o
+->
to
0.01
Post-Dev, no BMPs Post-Dev, with BMPs Future Climate, with BMPs Pre-Dev
0.001
S?
o
sP
sP
LO
O
00
cn
Flow-Exceedance Percentiles (Wet Days Only)
Figure 7-10. Runoff duration curve for CD3.4 with historic and future climate.
68
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FDC 2A Project
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0.3
0.2
0.1
0.0
0.0
0.5
1.0
1.0
0.9
0.8
0.7
0.6
0.5
0.4
n
lt^year 24-hour Storm (4.9 inch)
Rainfall (in./hr)
Selected 24-hours
C
eveloped, no BMPs
D
eveloped, with BMPs
P
re-ueveiopmeni
1.
a/I
K
/ V
AN.
ID
O
o
fNI
no
O
ID
O
tD
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lo
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o
ID
o
o
fNI
O
tD
O
UD
O
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fNI
r^
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ID
O
ID
O
o
fNI
00
o
ID
O
UD
O
O
fNI
ai
o
ID
O
ID
O
o
fNI
ID
O
ID
O
O
fNI
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FDC 2A Project
Draft Project Report
0.0
=s 0.5
1.0
3.0
2.5
2.0 H
1.5
1.0
0.5
0.0
r
10-year 24-hour Storm (4.9 inch)
Rainfall (in./hr)
Selected 24-hours
Post-Dev, no BMPs
-Post-Dev, with BMPs
Pre-Dev
111
¦ 1
SI
It ft
i
i
II
1
i
¦
1 1
IX)
o
o
CM
m
o
(X)
o
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o
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o
o
fN
CTl
O
IX)
o
IX)
O
O
fN
IX)
O
UD
O
O
fN
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FDC 2A Project
Draft Project Report
1,8
1.6
1.4
1,2
IT- 0.8
>-
if 0.6
0.4
I—
0.2
I i
I I
I a
Historic Future Historic Future Historic Future
Pre-Development Developed, no BMPs Developed, with
BMPs
Conventional Development Practices
Historic Future Historic Future Historic Future
Pre-Development Developed, no BMPs Developed, with
BMPs
Gl and CD Practices
600
500
400
_ 300
L_
>-
200
i/i
i/i
100
0
a
Historic Future Historic Future Historic Future Historic Future Historic Future Historic Future
Developed, no
BMPs
Pre-Development
Conventional Development Practices
Developed, with Pre-Development
BMPs
Developed, no
BMPs
Gl and CD Practices
Developed, with
BMPs
<5
St
o
c
3
EC
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
I I
Historic Future Historic Future Historic Future
Developed, no
BMPs
Pre-Development
Conventional Development Practices
Developed, with
BMPs
Historic Future Historic Future Historic Future
Pre-Development
Developed, no
BMPs
Gl and CD Practices
Developed, with
BMPs
:igure 7-13. Annualized TP, TSS, and Runoff load and removal cost for High Density Residential (HSG-C) conceptual
design for conventional development practices and Gl and conservation design practices with historic
climate.
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>-
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
i
Historic Future Historic Future Historic Future Historic Future Historic Future Historic Future
Developed, no
BMPs
Pre-Development
Conventional Development Practices
Developed, with Pre-Development
BMPs
Developed, no
BMPs
Gl and CD Practices
Developed, with
BMPs
>¦
-Q
to
180
160
140
120
100
80
60
40
20
0
¦ BR
_
Historic Future Historic Future Historic Future
Pre-Development Developed, no Developed, with
BMPs BMPs
Conventional Development Practices
Historic Future
Pre-Development
Historic Future
Developed, no
BMPs
Gl and CD Practices
Historic Future
Developed, with
BMPs
£
o
c
zs
cc
0.6
0.5
0.4
0.3
0.2
0.1
0
1
Historic Future Historic Future Historic Future Historic Future Historic Future Historic Future
Developed, no
BMPs
Pre-Development
Conventional Development Practices
Developed, with Pre-Development
BMPs
Developed, no
BMPs
Gl and CD Practices
Developed, with
BMPs
Figure 7-14. Annualized TP, TSS, and Runoff load and removal cost for High Density Commercial (HSG-A) conceptual
design for conventional development practices and Gl and conservation design practices with historic
climate.
72
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3
2.5
2
1.5
1
0.5
¦
_ „
1
Historic Future Historic Future Historic Future
Pre-Development Developed, no Developed, with
BMPs BMPs
Conventional Development Practices
Historic Future
Pre-Development
Historic Future
Developed, no
BMPs
Gl and CD Practices
Historic Future
Developed, with
BMPs
_o
l/l
l/l
1200
1000
800
600
400
200
0
Historic Future Historic Future Historic Future Historic Future Historic Future Historic Future
Pre-Development Developed, no
BMPs
Developed, with Pre-Development
BMPs
Conventional Development Practices
Developed, no
BMPs
G1 and CD Practices
Developed, with
BMPs
>¦
o
c
2
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
Historic Future Historic Future Historic Future
Developed, no
BMPs
Pre-Development
Conventional Development Practices
Developed, with
BMPs
Historic Future Historic Future Historic Future
Pre-Development
Developed, no
BMPs
Gl and CD Practices
Developed, with
BMPs
Figure 7-15. Annualized TP, TSS, and Runoff load and removal cost for Low Density Residential (HSG-C) conceptual
design for conventional development practices and Ql and conservation design practices with historic
climate.
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8. HRU SCALE MODELING ANALYSES
The surface and subsurface infiltration SCMs are the most efficient stormwater (SW) practices to meet small-
scale site control targets under current MassDEP (2008) and MS4 regulations. These regulations require SW
controls to be implemented if the projects fall below a certain regulatory threshold area of disturbance or
impervious cover. For example, MassDEP requires a threshold of 1 acre IC (approximately 30% of total IC
treated at the watershed scale) and a more stringent regulation requires a threshold of 1 /8th of an acre IC
(approximately 80% of total IC treated at the watershed scale). In practice, these requirements may not
provide enough treatment to protect water quality with continued future development and climate change.
The next generation of SCMs could provide greater water quality to maintain predevelopment groundwater
recharge and nutrient export.
8.1. HRU Scale Modeling Scenarios
To evaluate the performance of current and next-generation individual SCMs, they were simulated in the
Opti-Tool using a unit-area HRU approach. In the following sections, the current MassDEP and MS4
control SCMs are referred to as MS4 control SCMs and the next generation SCMs are referred to as High
control SCMs. Each control level is evaluated for surface and subsurface SCMs for HSGs A-D, with a high
and low infiltration rate for each HSG. For each combination of SCM category, HSG, and infiltration rate,
a design storage volume (DSV) necessary to reach the desired treatment efficiency and/or groundwater
recharge volume was calculated using the GI SCM performance curves. These performance curves were
developed for the infiltration basins and infiltration trenches for different soil types (HSG) using the long-
term continuous hourly rainfall data collected at Boston Logan airport. The regionally calibrated EPA
SWMM model was used to generate the runoff and pollutant loads and the regionally calibrated EPA Opti-
Tool was used to simulate the GI SCM to evaluate the performance under different DSV and native HSG
combinations.
MassDEP and MS4 Control
MassDEP (2008) requires capture depths of IC runoff no less than 0.6, 0.35, 0.25, and 0.1 inches for
predevelopment HSGs A, B, C, and D, respectively. Using a simple dynamic sizing method provided by
MassDEP, these depths translate into the DSVs shown in column "Recharge" of Table 8-1. The
performance curves for TSS do not include pretreatment for SCM. Therefore, a 10% additional reduction in
annual TTS load has been added to performance curves for determining DSVs shown in column "90% TSS
Reduction" of Table 8-1. The DSV for 60% TP reductions were derived directly from the performance
curves. The maximum required DSV was selected as the controlling size for the 16 GI SCM scenarios as
shown in Table 8-1.
Table 8-1. Impervious Cover HRU SCM Design Storage Volume (DSV) Sizing for MassDEP (2008) & MS4 level of
Control (MS4 Control)
SCM
Infiltration
Design Storage Volume (in)
Category
SCM Examples
HSG
Rate
(in/hr)
Controlling
Recharge
60% TP
Reduction
90% TSS
Reduction
A
8.27
0.36
0.36
0.10
0.20
Basin, swale,
raingarden (i.e.,
A
2.41
0.50
0.50
0.14
0.20
Surface
B
1.02
0.32
0.32
0.19
0.21
Infiltration
bioretention),
permeable pavement
B
0.52
0.34
0.34
0.22
0.22
C
0.27
0.27
0.24
0.27
0.20
C
0.17
0.29
0.25
0.29
0.20
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SCM
Infiltration
Design Storage Volume (in]
Category
SCM Examples
HSG
Rate
(in/hr)
Controlling
Recharge
60% TP
Reduction
90% TSS
Reduction
D
0.1
0.30
0.10
0.30
0.20
D
0.05
0.42
0.10
0.42
0.20
A
8.27
0.36
0.36
0.12
0.30
A
2.41
0.50
0.50
0.20
0.40
B
1.02
0.32
0.32
0.30
0.32
Subsurface
Trench, Chambers,
drywell, tree filter
retention
B
0.52
0.34
0.34
0.31
0.34
Infiltration
C
0.27
0.36
0.24
0.36
0.36
C
0.17
0.40
0.25
0.40
0.40
D
0.1
0.42
0.10
0.42
0.42
D
0.05
0.59
0.10
0.59
0.59
High Control
The predevelopment recharge was based on a Water Balance method for Boston MA using average annual
runoff yields from long-term continuous SWMM HRU models (1992-2020) of meadow and forested lands
for HSGs A, B, C, and D. Predevelopment recharge conditions were met when infiltration practices are
sized (via the DSVs) to capture 66%, 63%, 51% and 40% of average annual IC runoff volumes for HSGs A,
B, C, and D, respectively.
Predevelopment nutrient export is considered to be the nutrient load delivered in surface runoff from natural
wooded and meadow lands according to HSG. Required percent reductions to IC runoff TP export are 98%,
93%, 86%, and 77%, for predevelopment HSGs A, B, C, and D. Required percent reductions to IC runoff
TN export are 98%, 91%, 82%, and 71%, for predevelopment HSGs A, B, C, and D. The DSVs for High
control SCMs were estimated using the performance curves to meet the above mentioned required percent
reductions for TN, TP, and runoff volume as shown in Table 8-2. The maximum required DSV was
considered as the controlling size for each GI SCM scenario.
To test the resilience of High control SCMs under future climate conditions, eight additional scenarios were
run using the median RCP 8.5 ecodficit future climate as a boundary condition. These scenarios were for
infiltration basin and trench with HSG A, B, C, and D (infiltration rates of 2.41 in/hr, 0.52 in/hr, 0.17 in/hr,
and 0.05 in/hr, respectively).
Table 8-2. Impervious Cover HRU SCM Design Storage Volume (DSV) Sizing for Predevelopment Average Annual
Recharge and Nutrient Export Level of Control (High Control)
SCM
Infiltration
Design Storage Volume (in)
Category
SCM Examples
HSG
Rate
(in/hr)
Controlling
Predev
Recharge
Predev TP
Export
Predev TN
Export
Surface
Basin, swale,
A
8.27
0.39
0.15
0.39
0.39
Infiltration
raingarden
A
2.41
0.67
0.36
0.67
0.60
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SCM
Infiltration
Design Storage Volume (in)
Category
SCM Examples
HSG
Rate
(in/hr)
Controlling
Predev
Recharge
Predev TP
Export
Predev TN
Export
(i.e.,
bioretention),
permeable
B
1.02
0.59
0.37
0.59
0.39
B
0.52
0.73
0.46
0.73
0.42
pavement
C
0.27
0.60
0.40
0.60
0.33
C
0.17
0.69
0.50
0.69
0.35
D
0.1
0.60
0.50
0.60
0.25
D
0.05
0.86
0.86
0.80
0.30
A
8.27
0.60
0.20
0.60
0.60
A
2.41
1.00
0.56
1.00
0.80
Trench,
Chambers,
B
1.02
0.86
0.51
0.86
0.53
Subsurface
B
0.52
0.99
0.60
0.99
0.53
Infiltration
drywell, tree
filter retention
C
0.27
0.81
0.55
0.81
0.38
C
0.17
0.93
0.68
0.93
0.39
D
0.1
0.79
0.72
0.79
0.25
D
0.05
1.25
1.25
1.00
0.22
8.2. HRU Scale Opti-Tool Setup
Opti-Tool models were configured for each of the 32 combinations of control level, SCM, HSG, and
infiltration rate. Each SCM was sized using the DSV to treat runoff from 1 acre of commercial IC. Boundary
conditions for these models represent historic LULC and climate within the Upper Hodges Brook
subwatershed. The SCM parameters used in Opti-Tool are shown in Table 8-3. No optimization was
performed because SCMs were sized according to their required DSV which meets the MassDEP and MS4
standards. The predeveloped condition for each scenario was set as forested land cover with the
corresponding HSG.
Table 8-3. SCM specifications for HRU level models
General
Information
SCM Parameters
Infiltration Trench
Infiltration Basin
Surface
Storage
Configuration
Orifice Height (ft)
0
0
Orifice Diameter (in.)
0
0
Rectangular or Triangular Weir
Rectangular
Rectangular
Weir Height (ft)/Ponding Depth
(ft)
0.5
2
Crest Width (ft)
30
30
Depth of Soil (ft)
6
0
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General
Information
SCM Parameters
Infiltration Trench
Infiltration Basin
Soil
Properties
Soil Porosity (0-1)
0.6
0.4
Vegetative Parameter A
0.9
0.9
Soil Infiltration (in/hr)
Table 8-1 & Table 8-2
Table 8-1 & Table 8-2
Underdrain
Properties
Consider Underdrain Structure?
No
No
Storage Depth (ft)
0
0
Media Void Fraction (0-1)
0
0
Background Infiltration (in/hr)
N/A
N/A
Cost
Parameters
Storage Volume Cost ($/ft3)
$12.82
$6.41
Cost Function
Adjustment
SCM Development Type
New SCM in Undeveloped Area
New SCM in Undeveloped Area
Cost Adjustment Factor
1
1
Decay Rates
TSS (1/hr)
0.74
1.9
TN (1/hr)
0.42
0.42
TP (1/hr)
0.03
0.07
ZN (1/hr)
0.45
1.7
Underdrain
Removal
Rates
TSS (%, 0-1)
N/A
N/A
TN (%, 0-1)
N/A
N/A
TP (%, 0-1)
N/A
N/A
ZN (%, 0-1)
N/A
N/A
8.3. HRU Scale Modeling Results
The HRU scale modeling results were evaluated by comparison of annual average percent load reductions
and runoff duration curves. The cost per acre IC treated for each scenario is shown in Table 8-4. Annual
average percent reductions for the HRU scale models are shown in Table 8-5. For the same combination of
SCM, HSG, and infiltration rate, the High control SCMs achieve greater reductions than the MS4 control
SCM. Similarly, when only the infiltration rate is varied, the higher infiltration rate achieves slightly greater
reductions than the lower infiltration rate. One exception to this result was for HSG-D. The increase in SCM
capacity with the lower infiltration rate on these soils outweighed the benefit of the slightly higher infiltration
rate. Under the median future climate condition, the selected SCMs show only a minor decrease in
performance, indicating these High control SCMs still operate effectively (Table 8-6).
Runoff duration curves, which account for storm runoff only, were also created for each scenario (all RDCs
are presented in Appendix C). Figure 8-1 and Figure 8-2 provide example RDCs for an infiltration basin on
HSG-C with an infiltration rate of 0.17 in/hr for MS4 and High control levels, respectively. Examining these
two curves shows that the High control SCM, while not matching the predeveloped condition, does provide
reduced flows over a greater percentage of the time. Figure 8-3 and Figure 8-4 show similar curves for the
infiltration trench SCM.
When the High control SCMs are evaluated with the median future climate conditions (holding all other
parameters including SCM capacity constant), there is an increase in flow across the entire runoff duration
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curve that corresponds to the increased future precipitation. The impact on each RDC from future climate
varied by HSG. For example, infiltration basins and trenches on HSG A had only a slight increase in flow
(Figure 8-5 and Figure 8-9, respectively). SCMs on HSG B and HSG C had larger increases in flow compared
to the historic climate condition (Figure 8-6, Figure 8-7, Figure 8-10, Figure 8-11). HSG D has the lowest
infiltration rate and the highest flows across the RDC compared to the other HSGs. However, the increase
in flows for HSG D with the future climate condition was not as great as those for HSG B and HSG C
(Figure 8-8 and Figure 8-12).
Table 8-4. Summary of cost of unit-acre IC treated for HRU level SCM scenarios
SCM
Category
HSG
Design Storage
Volume (in.)
Infiltration Rate
(in./hr)
Cost/Acre IC Treated ($)
MS4
High
A
0.36
8.27
$8,378
$9,077
0.5
2.41
$11,636
$15,594
"i/5
ro
CO
c
o
B
0.32
1.02
$7,447
$13,732
0.34
0.52
$7,913
$16,990
¦4—1
ro
L_
C
0.27
0.27
$6,284
$13,964
-M
_c
0.29
0.17
$6,750
$16,059
D
0.3
0.1
$6,982
$13,964
0.42
0.05
$9,775
$20,015
A
0.36
8.27
$23,684
$39,474
_c
0.5
2.41
$32,899
$65,792
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Table 8-5. Annual average percent reductions for HRU level SCM scenarios
SCM
HSG
Infiltration
SCM Volume (ft3)
Flow Volume
TSS
TN
TP
Zn
Category
Rate (in/hr)
MS4
High
MS4
High
MS4
High
MS4
High
MS4
High
MS4
High
A
8.27
1307
1417
89%
91%
99%
99%
97%
98%
98%
99%
99%
99%
C
2.41
1816
2433
82%
89%
99%
100%
97%
98%
96%
98%
99%
100%
"oo
CO
CO
B
1.02
1162
2143
56%
76%
99%
100%
88%
96%
84%
94%
97%
99%
c
o
0.52
1235
2651
49%
76%
99%
100%
87%
96%
81%
94%
97%
99%
"+-1
ro
C
0.27
981
2179
34%
61%
98%
100%
81%
93%
70%
88%
96%
99%
-M
0.17
1053
2506
29%
58%
98%
100%
81%
93%
69%
87%
96%
99%
c
D
0.1
1090
2179
22%
41%
99%
100%
79%
90%
65%
81%
95%
98%
0.05
1525
3123
18%
36%
99%
100%
82%
92%
68%
83%
97%
99%
A
8.27
2929
4882
79%
91%
98%
99%
95%
98%
94%
98%
96%
99%
_c
u
2.41
4068
8136
71%
90%
98%
100%
94%
99%
91%
98%
95%
99%
c
(D
B
1.02
2604
6997
46%
78%
95%
99%
86%
97%
76%
94%
89%
98%
H
C
0.52
2766
8055
40%
76%
95%
99%
86%
97%
72%
93%
| 88%
98%
o
¦4—1
ro
C
0.27
2929
6590
33%
61%
96%
99%
85%
95%
69%
87%
87%
96%
•M
0.17
3255
7567
29%
57%
96%
99%
85%
95%
68%
87%
| 88%
96%
c
D
0.1
3417
6428
22%
38%
96%
99%
85%
92%
66%
80%
87%
94%
0.05
4800
10171
17%
35%
I 97%
99%
87%
95%
69%
84%
1 89%
96%
Table 8-6. Change in annual average percent reduction for selected HRU-level SCM scenarios with a future climate
SCM
HSG
Infiltration
Rate (in/hr)
Flow
Volume
TSS
TN
TP
Zn
Category
High
High
High
High
Infiltration
Basin
A
2.41
-1.1%
-0.1%
-0.3%
-0.4%
-0.1%
B
0.52
-6.0%
-0.1%
-0.9%
-2.2%
-0.2%
C
0.17
-7.4%
0.0%
-1.2%
-2.9%
-0.3%
D
0.05
-2.2%
0.0%
-0.4%
-1.7%
-0.1%
Infiltration
Trench
A
2.41
-1.5%
0.1%
-0.2%
-0.5%
-0.2%
B
0.52
-6.6%
0.2%
-0.6%
-2.6%
-0.6%
C
0.17
-6.7%
0.3%
-0.6%
-3.2%
-0.6%
D
0.05
-1.8%
0.2%
-0.2%
-2.3%
-0.2%
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-Post-Dev, no BMPs Post-Dev, with BMPs Pre-Dev
i/i
4"
o.i
3=
o
c
3
oc 0.01
E
o
4->
0.001
0.0001
\p \0 \0 \0 sP Sp \0 vO \P \0 \0 \0 vO sP Sp Sp sp sp Sp xP vO
OS ON OS ON OS OS OS OS ffs oS ON OS OS ON OS OS ON OS OS ON OS
O LD O LT) O LO O LD O LO O LO O LO O LT) O LO O LTJ O
vHTHrNirMcom^'d-LnLniDtDr^r^ooooCTicxiO
rH
Flow-Exceedance Percentiles (Wet Days Only)
Figure 8-1. Runoff duration curve for MS4 control level infiltration basin on HSG C with an infiltration rate of 0.17 in/hr.
Post-Dev, no BMPs Post-Dev, with BMPs Pre-Dev
0.001
Figure 8-2. Runoff duration curve for High control level infiltration basin on HSG C with an infiltration rate of 0.17
in/hr.
0.0001
5? 5? 5?
O LD O
Np Sp Sp Sp Sp Sp Sp Sp Sp Sp Np
ON ON ON ON ON ON ON OS ON oN oS
i_n o lo o lh o lo o lh o lo
m^^-LnLn^D^r^rvooco
Flow-Exceedance Percentiles (Wet Days Only)
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-Post-Dev, no BMPs
-Post-Dev, with BMPs
Pre-Dev
0.1
O
c
3
DC
E
o
4->
(~)
0.01
0.001
0.0001
s? s? s?
o in o
\P \0 S.O \P \0 N.O
QV ON cJv 0s" ON on
LH O LO O LD O
t—I rsl rsi ro ro ^1"
Np \0 vO sP Np Np \0 nO sP Np
ON OS ON ov ON OS 0s- 0s* CTN
O LO O LO O LTt O LO O LTJ
LnLnuDiDr-.r^ooooCTicxi
Flow-Exceedance Percentiles (Wet Days Only)
Figure 8-3. Runoff duration curve for MS4 control level infiltration trench on HSG C with an infiltration rate of 0.17
in/hr.
Post-Dev, no BMPs Post-Dev, with BMPs Pre-Dev
0.0001
vO Sp Np nO nO nO
CTn Cjn On ON OS OS
LO O LO O LO O
fN ro m ^ m
nP \u nP nP \o nP nP \o sp \o
ON ON ffs ON ON ON ON ON ON ON
LO O LH o lh o ld o ld o
LnuDuDr^r^ooooa^o^o
Flow-Exceedance Percentiles (Wet Days Only)
Figure 8-4. Runoff duration curve for High control level infiltration trench on HSG C with an infiltration rate of 0.17
in/hr.
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Post-Dev, no BMPs Post-Dev, with BMPs Future Climate, with BMPs
Pre-Dev
0.001
sp \p vO \0 \0 sP sP nP \0 sp sP sP sp sP sp \0 sp sp sP sp sP
0\ OS cys 0s* oS oS 0s" 0s- Os OS OS OS- os 0s- 0*s OS OS os
O lT) O LH O LO O LT) O LO O L-O O LO O LO O LO O LO O
*H*Hrsjrsimro^t^fLnLnvD^Dr^r^oocx)o,io>>o
rH
Flow-Exceedance Percentiles (Wet Days Only)
Figure 8-5. Runoff duration curve for High control level infiltration basin on HSG A with an infiltration rate of 2.41
in/hr with historic and future climate.
Post-Dev, no BMPs Post-Dev, with BMPs Future Climate, with BMPs Pre-Dev
0.001
•sP Sp sp sp sP sp sp sp sp sP sp sp sp sp sP sP sp sp sp SP sp
OS os os OS os Os os os OS os OS OS os os os OS os os OS OS o^
O LO O LO O LO O LO O LO O LD O LD O LD O LD O LD O
*-HtHrsirsimm^r«3-Lni-n<*oi£>r-shsoooo(T>cr)0
rH
Flow-Exceedance Percentiles (Wet Days Only)
Figure 8-6. Runoff duration curve for High control level infiltration basin on HSG B with an infiltration rate of 0.52
in/hr with historic and future climate.
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Post-Dev, no BMPs Post-Dev, with BMPs Future Climate, with BMPs Pre-Dev
1
0.001
SO
\P
\0
nP
NO
SP
SP
SP
\p
o
LO
o
LO
O
LO
o
LO
O
LO
O
LO
O
m
m
LO
LO
UD
UD
00
00
cr»
Flow-Exceedance Percentiles (Wet Days Only)
Figure 8-7. Runoff duration curve for High control level infiltration basin on HSG C with an infiltration rate of 0.17
in/hr with historic and future climate.
Post-Dev, no BMPs Post-Dev, with BMPs Future Climate, with BMPs Pre-Dev
0.001
\0 vp Np \0 vp \0 \0 sp VP Sp Vp Sp SP SP VP VP SP sp sP NP
OS 0s- 0s- 0s* 0s" ds 0s* 0s- ffv, ©v. 0s- 0s- 0s-
O lO O LO O LT) O LO O LO O LD O LD O LH O LO O LO O
^HrHrvj(Nmm^-^LnLn«x>uDr^r^oooocr»cno
rH
Flow-Exceedance Percentiles (Wet Days Only)
Figure 8-8. Runoff duration curve for High control level infiltration basin on HSG D with an infiltration rate of 0.05
in/hr with future climate.
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Post-Dev, no BMPs Post-Dev, with BMPs Future Climate, with BMPs Pre-Dev
0.001
3?
o
Flow-Exceedance Percentiles (Wet Days Only)
Figure 8-9. Runoff duration curve for High control level infiltration trench on HSG A with an infiltration rate of 2.41
in/hr with future climate.
Post-Dev, no BMPs Post-Dev, with BMPs Future Climate, with BMPs Pre-Dev
0.001
sp sP nP \0 \o \o \o \o \0 \o \0 sp nP nP sp sp sp sP sp sP sP
0s* 0"N o > 0s- 0s* 0s- 0s- 0s* 0s- 0s* 0s* 0s- OS 0\ 0s" 0s"
O lH O LD O LO O LO O LO O LD O LD O LO O LT) O LO O
TH^HrMrNjroro^r^d-LriLnkDuDr^r^cxDoocTicno
T—I
Flow-Exceedance Percentiles (Wet Days Only)
Figure 8-10. Runoff duration curve for High control level infiltration trench on HSG B with an infiltration rate of 0.52
in/hr with future climate.
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Post-Dev, no BMPs Post-Dev, with BMPs Future Climate, with BMPs Pre-Dev
1
0.001
a? as a?
O u-> O
SP \P N.O sP sp \0 S.O SO \0 \0 sP
pv. ps. OS ps QS ps pS oN ps ps, ps.
LnoLnoLnoLnOLDOLn
mU3i^i^oooo
Flow-Exceedance Percentiles (Wet Days Only)
sp
\o
so
o
LO
O
CD
CT>
O
^—1
1
0.1
0.01
0.001
15%
Figure 8-11. Runoff duration curve for High control level infiltration trench on HSG C with an infiltration rate of 0.17
in/hr with future climate.
to
*4—
u
it
o
c
3
DC
0.1
o
4->
to
0.01
0.001
Figure 8-12
Future Climate, with BMPs Pre-Dev
1
0.1
0.01
0.001
5% 10% 15%
Runoff duration curve for High control level infiltration trench on HSG D with an infiltration rate of 0.05
in/hr with future climate.
Post-Dev, no BMPs
Post-Dev, with BMPs
Flow-Exceedance Percentiles (Wet Days Only)
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9. WATERSHED SCALE MODELING ANALYSES
This section demonstrates the impact of GI SCM designed to meet MassDEP and MS4 stormwater
standards as well as high-level controls that provide groundwater recharge similar to the predevelopment
hydrology in the Upper Hodges Brook watershed. The DSVs for GI SCM and HSG combinations used in
the HRU scale modeling were scaled to the impervious area being treated by different GI SCM from different
land use and HSG combinations at the watershed scale. The following sub-sections provide the detail of all
modeling scenarios with existing and predicted future land use/land cover under historical and future
predicted climate conditions in the Upper Hodges Brook watershed.
9.1. Watershed Scale Next-Generation SCM Modeling Scenarios
Watershed scale Opti-Tool models were run for scenarios including historic and future land use-land cover,
historic and median RCP 8.5 future climate, and varying percentages of IC treatment. These scenarios
evaluate the MS4 and High control HRU level SCMs and are shown in Table 9-1. These twelve scenarios
are repeated for 100% IC treatment, 80% IC treatment, and 30% IC treatment for a total of 36 scenarios.
Table 9-1. Table of watershed-scale modeling scenarios using HRU level SCMs
Scenario
Number
Control Level
Land use / Land cover
Weather
1
2016 Baseline IC (treated)
Historical
2
MassDEP and MS4
2016 Baseline IC (treated)
Future Median
3
(existing standard
Scenario 1 + 2060 increase in IC (untreated)
Historical
4
for recharge and
Scenario 2 + 2060 increase in IC (untreated)
Future Median
5
load reduction)
Scenario 1 + 2060 increase in IC (treated)
Historical
6
Scenario 2 + 2060 increase in IC (treated)
Future Median
7
2016 Baseline IC (treated)
Historical
8
High (PreDev
Recharge and no net
increase in load)
2016 Baseline IC (treated)
Future Median
9
Scenario 7 + 2060 increase in IC (untreated)
Historical
10
Scenario 8 + 2060 increase in IC (untreated)
Future Median
11
Scenario 7 + 2060 increase in IC (treated)
Historical
12
Scenario 8 + 2060 increase in IC (treated)
Future Median
9.2. Watershed Scale Opti-Tool Setup
Configuration of Opti-Tool models for the watershed scale scenarios used the same number and type of
SCMs by land use and soil combinations as in the FDC1 (Phase 1) project. Namely, runoff from non-roof
IC for a given land use type was treated by infiltration basins for HSG A, B, and C and by biofiltration for
HSG-D. Rooftop runoff was treated by infiltration trenches on HSG A, B, and C. The SCM drainage areas
and footprints are given in Table 9-2 and Table 9-3 respectively; SCM parameters are shown in Table 9-4.
Infiltration rates were the lower rate for each HSG used in the HRU scale modeling. No optimization was
performed as SCM sizes were determined based on the drainage area and unit-area DSV.
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Table 9-2. SCM drainage areas (ac) for watershed scale scenarios by the percentage of IC treated
S3
O
IC Treated (%) and LULC Type
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S3
O
•
IC Treated (%) and LULC Type
53 &
Pn
rn >>»
SCM Type
HSG
30%
80%
100%
§ H
CJ
C/5
Q
Historic
Future
Historic
Future
Historic
Future
A
0.00
0.00
0.00
0.00
0.00
0.00
Infiltration
Trench
a
P
B
0.73
1.40
1.94
3.74
2.42
4.68
cfc!
o
o
C
0.13
0.26
0.36
0.69
0.45
0.87
Pi
Porous
Pavement
D
0.00
0.00
0.00
0.00
0.00
0.00
Other IC
Infiltration
basin
A
0.00
0.01
0.01
0.02
0.02
0.03
B
0.57
1.11
1.53
2.95
1.91
3.69
C
0.17
0.33
0.46
0.88
0.57
1.10
Biofiltration
D
0.87
1.68
2.32
4.47
2.90
5.59
Infiltration
Trench
A
0.00
0.00
0.00
0.00
0.00
0.00
a
o
B
0.00
0.00
0.00
0.00
0.00
0.00
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Table 9-3. SCM footprints (ft2) for watershed scale scenarios by the percentage of IC treated and LULC and climate boundary conditions
Oh
2
Pi
Porous
Pavement
D
0
0
0
0
0
0
0
0
0
0
0
0
a
i—i
Other IC
Infiltration
basin
A
1,150
1,256
1,541
1,683
3,067
3,349
4,110
4,488
3,834
4,186
5,137
5,610
B
277
303
595
650
740
807
1,588
1,734
924
1,009
1,985
2,167
C
8,613
9,405
20,494
22,377
22,969
25,080
54,650
59,673
28,711
31,350
68,313
74,591
Biofiltration
D
19,450
21,238
39,827
43,487
51,867
56,634
64,834
70,793
Infiltration
Trench
A
723
2,476
1,445
4,952
1,927
6,603
3,854
13,206
2,409
8,254
4,817
16,507
£ C
a
o
B
163
557
473
1,622
434
1,486
1,263
4,326
542
1,857
1,578
5,408
p 3
C/3
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Oh
3
o
Vh
a
CJ
-------
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Oh
3
o
Vh
a
CJ
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Table 9-4. SCM specifications for watershed scale scenarios
General
Information
SCM Parameters
Infiltration Trench
Infiltration Basin
Biofiltration
Surface
Storage
Configuration
Orifice Height (ft)
0
0
0
Orifice Diameter
(in.)
0
0
0
Rectangular or
Triangular Weir
Rectangular
Rectangular
Rectangular
Weir Height
(ft)/Ponding Depth
(ft)
0.5
2
0.5
Crest Width (ft)
30
30
30
Soil
Properties
Depth of Soil (ft)
6
0
2.5
Soil Porosity (0-1)
0.4
0.4
0.2
Vegetative
Parameter A
0.9
0.9
0.9
Soil Infiltration
(in/hr)
Table 8-1 & Table 8-2,
Lower value by HSG
Table 8-1 & Table 8-2,
Lower value by HSG
2.5
Underdrain
Properties
Consider
Underdrain
Structure?
No
No
Yes
Storage Depth (ft)
0
0
1
Media Void Fraction
(0-1)
0
0
0.4
Background
Infiltration (in/hr)
N/A
N/A
0.05
Cost
Parameters
Storage Volume
Cost ($/ft3)
$12.82
$6.41
$15.87
Cost Function
Adjustment
SCM Development
Type
New SCM in
Undeveloped Area
New SCM in
Undeveloped Area
New SCM in
Undeveloped Area
Cost Adjustment
Factor
1
1
1
Decay Rates
TSS (1/hr)
0.74
1.9
0.79
TN (1/hr)
0.42
0.42
0.01
TP (1/hr)
0.03
0.07
0.01
ZN (1/hr)
0.45
1.7
0.49
Underdrain
Removal
Rates
TSS (%, 0-1)
N/A
N/A
0.89
TN (%, 0-1)
N/A
N/A
0.015
TP (%, 0-1)
N/A
N/A
0.23
ZN (%, 0-1)
N/A
N/A
0.84
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9.3. Watershed Scale Modeling Results
The watershed-scale modeling results were evaluated by comparison of annual average percent load
reductions, ecodeficit/ecosurplus, and flow duration curves. The capital cost and the cost per acre IC treated
for each scenario are shown in Table 9-5. Annual average percent reductions, as evaluated at the watershed
outlet, are shown in Table 9-6; Table 9-7 presents these metrics but are evaluated for the load from IC only
since no pervious areas were treated by any of the modeled scenarios. All FDCs from the watershed scale
modeling are presented in Appendix D.
There are several ways to compare the watershed scale scenarios. First, annual average load reductions can
be compared between the same scenario but with varying percentages of IC treated. The 30% IC treated
represents an estimate of the amount of IC treated at the watershed scale when the projects fall under a
regulatory threshold area of 1-acre disturbance or impervious cover, while 80% IC treated represents a more
stringent regulation that requires a threshold of 178th of an acre IC. Treatment of 100% of the IC is included
as a theoretical maximum. Increasing the percentage of IC treated understandably leads to greater treatment
and lower loads to receiving waters.
A second way to compare the results of the watershed scale modeling is at the same scenario, but for different
control levels. For instance, Scenarios 1 and 7 both have historic boundary conditions but use the MS4 and
High control SCMs, respectively. High control under these conditions, and with 80% IC treated, achieves
an 11% greater TP reduction than the MS4 control level. This comparison can be extended to the FDCs
(Figure 9-1 and Figure 9-2) and ecosurplus/ecodeficit (Figure 9-5). Visual differences in the FDCs can be
subtle, however, their cumulative impact is seen in the ecosurplus and ecodeficit values. In this example, the
High control SCMs have a slightly lower ecosurplus (by 2.6 MG/yr).
The third comparison of results can be made between the same control level, but with varying boundary
conditions. Figure 9-1 and Figure 9-2 show an example of this between High control SCMs with historic
LULC and climate (Scenario 7) compared to High control SCMs with future LULC and climate (Scenario
12). Between these scenarios, there is an increase in ecodeficit and ecosurplus (6.5 MG/yr, 248 MG/yr,
respectively) which demonstrates the impact of increased IC coupled with increased precipitation and
temperature on the flow duration curve. While these scenarios both treat 80% of the IC, the area treated and
SCM capacity is greater under the future LULC condition.
Table 9-5. Summary of total cost and cost of unit-acre IC treated for each scenario at the watershed-scale
Scenario
Control
IC Area Treated (ac)
Total Cost ($)
Cost/Acre IC
Level
30%
80%
100%
30%
80%
100%
Treated ($)
1
127
339
424
$2,028,935
$5,410,492
$6,763,114
$15,947
2
127
339
424
$2,028,935
$5,410,492
$6,763,114
$15,947
3
MS4
127
339
424
$2,028,935
$5,410,492
$6,763,114
$15,947
4
127
339
424
$2,028,935
$5,410,492
$6,763,114
$15,947
5
170
454
568
$2,717,964
$7,247,905
$9,059,881
$15,962
6
170
454
568
$2,717,964
$7,247,905
$9,059,881
$15,962
7
127
339
424
$4,294,313
$11,451,500
$14,314,377
$33,753
8
127
339
424
$4,294,313
$11,451,500
$14,314,377
$33,753
9
High
127
339
424
$4,294,313
$11,451,500
$14,314,377
$33,753
10
127
339
424
$4,294,313
$11,451,500
$14,314,377
$33,753
11
170
454
568
$5,721,734
$15,257,954
$19,072,444
$33,603
12
170
454
568
$5,721,734
$15,257,954
$19,072,444
$33,603
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Table 9-6. Watershed total annual average percent reductions for watershed level scenarios with 30%, 80%, and 100% IC treated
Scenario
1
2
3
4
5
6
MS4
23.2%
62.3%
78.1%
16.1%
42.1%
52.6%
13.4%
34.4%
42.9%
23.1%
61.7%
77.3%
23.5%
63.2%
79.2%
16.1%
41.8%
52.2%
13.1%
33.2%
41.3%
23.1%
61.4%
76.9%
17.9%
48.2%
60.4%
12.7%
33.1%
41.4%
11.0%
28.1%
35.1%
18.7%
49.9%
62.5%
18.0%
48.5%
60.8%
12.6%
32.7%
40.9%
10.6%
27.0%
33.6%
18.6%
49.4%
61.9%
24.7%
66.5%
83.4%
16.9%
44.2%
55.3%
14.7%
38.0%
47.5%
24.3%
65.1%
81.5%
24.8%
66.8%
83.8%
16.8%
43.7%
54.6%
14.3%
36.5%
45.5%
24.2%
64.5%
80.8%
7
8
9
10
11
12
High
24.6%
66.1%
82.8%
18.7%
50.0%
62.7%
16.9%
45.1%
56.4%
25.2%
67.5%
84.6%
24.8%
66.9%
83.8%
18.6%
49.7%
62.2%
16.3%
43.6%
54.6%
25.1%
67.5%
84.6%
19.0%
51.2%
64.1%
14.7%
39.4%
49.3%
13.8%
36.9%
46.1%
20.3%
54.6%
68.4%
19.1%
51.3%
64.3%
14.5%
38.9%
48.7%
13.3%
35.4%
44.3%
20.2%
54.3%
68.1%
26.2%
70.5%
88.3%
19.5%
52.4%
65.6%
18.4%
49.3%
61.6%
26.4%
71.0%
88.9%
26.2%
70.7%
88.5%
19.3%
51.7%
64.8%
17.8%
47.4%
59.3%
26.3%
70.7%
88.5%
Table 9-7. Impervious cover annual average percent reductions for watershed level scenarios with 30%, 80%, and 100% IC treated
Scenario
1
27.0%
72.6%
91.1%
19.6%
51.4%
64.2%
17.0%
43.6%
54.3%
25.4%
67.8%
85.0%
2
27.2%
73.2%
91.8%
19.3%
50.3%
62.8%
16.4%
41.5%
51.6%
25.1%
66.9%
83.8%
3
MS4
19.6%
52.8%
66.3%
14.8%
38.8%
48.5%
12.8%
32.9%
41.0%
19.6%
52.3%
65.6%
4
19.8%
53.2%
66.8%
14.6%
38.0%
47.4%
12.4%
31.3%
39.0%
19.4%
51.6%
64.7%
5
27.0%
72.9%
91.4%
19.7%
51.8%
64.7%
17.2%
44.5%
55.5%
25.5%
68.3%
85.5%
6
27.3%
73.4%
92.1%
19.5%
50.7%
63.3%
16.6%
42.4%
52.9%
25.2%
67.4%
84.4%
7
28.6%
77.1%
96.6%
22.8%
61.1%
76.5%
21.4%
57.1%
71.4%
27.6%
74.2%
93.0%
8
28.8%
77.4%
97.0%
22.3%
59.8%
74.9%
20.4%
54.5%
68.2%
27.4%
73.6%
92.2%
9
High
20.8%
56.1%
70.3%
17.2%
46.1%
57.7%
16.1%
43.1%
53.9%
21.3%
57.3%
71.7%
10
20.9%
56.3%
70.6%
16.9%
45.1%
56.5%
15.4%
41.1%
51.5%
21.1%
56.8%
71.1%
11
28.7%
77.3%
96.8%
22.9%
61.3%
76.7%
21.5%
57.6%
72.0%
27.7%
74.4%
93.2%
12
28.8%
77.6%
97.2%
22.4%
60.0%
75.1%
20.6%
55.1%
68.9%
27.4%
73.8%
92.5%
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0.1
Developed, no BMPs Developed, with BMPs Pre-Development
Developed, no BMPs Ecodeficit: 0.00 cfs (0.0 MG/year)
Developed, no BMPs Ecosurplus: 2.18 cfs (515.0 MG/year)
Developed, with BMPs Ecodeficit: 0.00 cfs (0.0 MG/year)
Developed, with BMPs Ecosurplus: 2.17 cfs (510.8 MG/year)
Flow-Exceedance Percentiles
Figure 9-1 Flow duration curve with MS4 control of 80% of the Upper Hodges Brook subwatershed's impervious cover
under historic LULC and climate conditions (Scenario 1).
Developed, no BMPs Developed, with BMPs Pre-Development
0.1
Developed, no BMPs Ecodeficit: 0.00 cfs (0.0 MG/year)
Developed, no BMPs Ecosurplus: 2.18 cfs (515.0 MG/year)
Developed, with BMPs Ecodeficit: 0.00 cfs (0.0 MG/year)
Developed, with BMPs Ecosurplus: 2.15 cfs (508.1 MG/year)
Flow-Exceedance Percentiles
Figure 9-2. Flow duration curve with High control of 80% of the Upper Hodges Brook subwatershed's impervious
cover under historic LULC and climate conditions (Scenario 7).
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Developed, no BMPs Developed, with BMPs Pre-Development
0.1
Developed, no BMPs Ecodeficit: 0.29 cfs (68.0 MG/year)
Developed, no BMPs Ecosurplus: 2.03 cfs (479.1 MG/year)
Developed, with BMPs Ecodeficit: 0.05 cfs (11.7 MG/year)
Developed, with BMPs Ecosurplus: 1.76 cfs (416.3 MG/year)
Flow-Exceedance Percentiles
Figure 9-3. Flow duration curve with MS4 control of 80% of the Upper Hodges Brook subwatershed's impervious
cover under historic LULC and climate conditions (Scenario 6).
Developed, no BMPs Developed, with BMPs Pre-Development
0.1
Developed, no BMPs Ecodeficit: 0.29 cfs (68.0 MG/year)
Developed, no BMPs Ecosurplus: 2.03 cfs (479.1 MG/year)
Developed, with BMPs Ecodeficit: 0.00 cfs (0.2 MG/year)
Developed, with BMPs Ecosurplus: 1.68 cfs (397.0 MG/year)
Flow-Exceedance Percentiles
Figure 9-4 Flow duration curve with High control of 80% of the Upper Hodges Brook subwatershed's impervious
cover under future LULC and climate conditions (Scenario 12).
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0
2
U1
D
500 -
400
300
01 200
o
u
LU
100 -
0
0
10 -
20 -
>,
0
u
30 -
t 40
X3
o
u
LU
50 -
60 -
70 -
-r—
1
-r-
2
-r-
3
IC Treated (%)
1 0 I 1 30 I 1 80
!![,¦ 114a up Ufa i if
IC Treated f%)
] 30 80
~r-
4
-^4*-
100
nia
100
I
6
r~
7
8
I
9
"10"
Scenario
I
11
I
12
Figure 9-5. Comparison of ecosurpluses arid deficits for each watershed scale scenario and percentage of IC treated.
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10. CONCLUSIONS AND RECOMMENDATIONS
This report presented a quantitative analysis of Flow Duration Curves (FDCs) and other associated metrics
for understanding the impact of land use decision-making on freshwater flow regimes and ecosystem health.
These analyses were based on long-term continuous hydrologic models developed under Phase 1 of this
project for the Taunton River Basin in eastern Massachusetts using the Loading Simulation Program in C++
(LSPC) and EPA's stormwater best management practices optimization (Opti-Tool) models. This report
(Phase 2A) conceptualized, evaluated, and communicated the benefits of next-generation conservation-
focused development and stormwater management practices.
In this report, a wide range of scenarios were evaluated from individual source control measures (SCMs) to
conservation-focused conceptual new and redevelopment sites, to a small urbanized watershed using both
historic and future projections of land use and climate. Results presented in this report indicate that
individual conservation-focused SCMs, when sized to maintain predevelopment hydrologic conditions, can
achieve 95% and 90% reductions in annual average Total Nitrogen (TN) and Total Phosphorous (TP) load,
respectively. These High control SCMs outperform conventional (MS4) control SCMs by 8% for TN and by
13% for TP. When individual High control SCMs are combined within a new or redevelopment site, they
can be configured as a system to achieve goals such as maintaining resilient, predevelopment hydrology with
little to no net increase in nutrient loads. This was demonstrated for a high-density residential site and a
high-density commercial site in this report.
Recommendations from the findings in this report include the following:
• First, the SCMs evaluated in this report represent structural controls for treating runoff from
impervious surfaces. However, there is a need to look at the impact of treating pervious areas in
order to meet watershed load reduction targets. Source control (e.g., fertilizer reduction, leaf pickup,
pet waste, etc.) should be added to the modeling to reflect more holistic stormwater management.
• Second, while the GI and CD SCMs evaluated in this report are an improvement over conventional
development practices, additional increases to required design storage volumes should be explored.
For instance, another set of SCMs that uses a static 1-in DSV could be compared to the High control
SCMs.
• A conceptual design for a low-density residential site in this report used IC disconnection as an SCM.
IC disconnection, with and without temporary storage as well as Gl-like green roofs, should be
further evaluated and their secondary or co-benefits should be included to the extent possible.
This report adds to a body of work that envisions the next generation of stormwater management practices.
Stormwater management requires multifaceted approaches including structural controls similar to those
evaluated here, as well as source control from developed pervious areas and locally driven conservation-
focused regulations and ordinances to be most effective. Evaluating the impact of structural and source
controls in combination at the watershed level in future work would provide valuable insights for next-
generation conservation development and stormwater management.
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11. REFERENCES
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Hydrological Indicators in the U.S. Northeast. Clim Dyn 28, 381-707. https://doi.org/10.1007
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Marasco, D. E., Hunter, B. N., Culligan, P. J., Gaffin, S. R., &McGillis, W. R. (2014). Quantifying
evapotranspiration from urban green roofs: A comparison of chamber measurements with commonly
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NELF, n.d. New England Landscape Futures Project [WWW Document], URL
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Paradigm Environmental and Great Lakes Environmental Center, 2021. Holistic watershed management
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Razzaghmanesh, M., & Beecham, S. (2014). The hydrological behaviour of extensive and intensive green
roofs in a dry climate. Science of the Total Environment, 499(1), 284-296.
https://doi.Org/10.1016/j.scitotenv.2014.08.046
Thompson, J.R., Plisinski, J.S., Lambert, K.F., Duveneck, M.J., Morreale, L., McBride, M., MacLean,
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Thompson, J.R., Plisinski, J.S., Olofsson, P., Holden, C.E., Duveneck, M.J., 2017. Forest loss in New
England: A projection of recent trends. PLoS One 12.
https://doi.org/10.1371/JOURNAL.PONE.0189636
USEPA (United States Environmental Protection Agency). 2012. Report on Enhanced Framework
(SUSTAIN) and Field Applications to Placement of BMPs in Urban Watersheds. U.S.
Environmental Protection Agency, Washington, DC, EPA/600/R-11/144, 2012.
USEPA (United States Environmental Protection Agency). 2009. SUSTAIN - A Framework for
Placement of Best Management Practices in Urban Watersheds to Protect Water Quality. U.S.
Environmental Protection Agency, Washington, DC, EPA/600/R-09/095, 2009.
Walsh, C.J., Booth, D.B., Burns, M.J., Fletcher, T.D., Hale, R.L., Hoang, L.N., Livingston, G., Rippy,
M.A., Roy, A.H., Scoggins, M., Wallace, A., 2016. Principles for urban stormwater management to
protect stream ecosystems, in: Freshwater Science. University of Chicago Press, pp. 398-411.
https://doi.org/10.1086/685284
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