Advancement of Salinity and Flow Monitoring
in the San Francisco Bay Delta
San Francisco Bay Delta Action Plan Implementation
Support
FINAL REPORT
Contract No. EP099BOA001
Prepared by:
David B. Hericks1, Sujoy B. Roy1, Jon Burau2, and Erin Foresman3
1Tetra Tech, Inc.
3746 Mount Diablo Blvd., Suite 300
Lafayette, CA 94549
California Water Science Center
US Geological Survey
6000 J Street, Placer Hall
Sacramento, CA 95819
3U.S. Environmental Protection Agency Region 9
75 Hawthorne Street
San Francisco, California 94105
February 2017
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Executive Summary
This report evaluates the cost and utility of adding coupled surface and near-bottom salinity
monitors along the axis of the San Francisco Estuary, and the types of equipment and
approximate costs of this additional monitoring effort. Expanding the monitoring network
by adding downstream monitoring stations, adding stations at depth, and increasing the
resolution of monitoring stations along the axis of the estuary will generate data that
capture tidal dynamics and may be used to derive equations that predict salinity and other
hydrodynamic endpoints with greater precision than currently possible. The proposed
monitoring is expected to enhance the hydrodynamic modeling of the salt field and the
accuracy of compliance and prediction methods in the estuary.
Springtime outflows through the San Francisco Estuary are managed through the position
of the 2 parts per thousand bottom salinity isohaline (X2) along the center-line of the
estuary, measured in kilometers relative to the Golden Gate Bridge. X2 is calculated from
surface salinity measurements with a constant vertical conversion factor. The current
framework of sampling stations does not collect near-bottom salinity along the estuary
center-line, does not extend far enough down-estuary to adequately characterize X2 during
high flows, and the separation of monitoring locations limits the precision with which the
position of X2 can be calculated.
Near-surface and near-bed salinity and turbidity sensors and ancillary hardware could be
added to the estuary for an estimated cost of ~ $780K in capital costs and $500K/yr in
operation, maintenance, and data processing costs based on a proposed addition to an
existing surface salinity network in San Francisco Estuary operated by the US Geological
Survey. While this document does not recommend a particular plan for implementation,
the compiled information provides rough costs for planning considerations. Data collected
through a network of this kind could improve precision of compliance methods with the
existing Delta outflow standard. With data collected over time, it would support
modifications to a new/modified Delta outflow standard, improve our ability to assess the
effectiveness of water quality standards, and improve protection of water supply and
aquatic life habitat. These data would also improve the salinity modeling capability and
accuracy for future predictions and past evaluations. Expanding the monitoring network
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also provides a platform to connect hydrodynamic and biological measurements which is
necessary for integrating biological and hydrodynamic modeling and advancing
knowledge of estuarine mechanisms that influence fish population trends. The specific
design of a monitoring network and whether or not the improvements can be optimized for
their potential outputs was beyond the scope of the present document and needs to be based
on a broader discussion among science experts, regulators, and the regulated community.
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Table of Contents
1 Introduction 1-1
1.1 Purpose 1-1
1.2 Report Goals 1-2
2 Flow and Salinity in San Francisco Estuary 2-1
2.1 Behavior of the Salt Field and Delta Outflow in San Francisco Estuary 2-1
2.2 Summary of Delta Outflow Objective and X2 2-4
2.3 Estimating, Measuring, and Error in Delta outflow 2-5
2.4 Estimating, Measuring, and Error in Salinity and the X2 Isohaline 2-6
2.4.1 X2 Model-based Calculations 2-7
2.4.2 X2 Calculation by Interpolation 2-10
3 Existing Monitoring Network 3-1
3.1 Interagency Ecological Program - Environmental Monitoring Program 3-2
3.2 US Geological Survey (USGS) Monitoring Network 3-4
3.2.1 Water Quality Monitoring 3-7
3.2.2 Flow (Discharge) Monitoring 3-9
4 Desired Improvements in Salinity and Flow Monitoring 4-1
4.1 Deficiencies in Existing Monitoring Data and for Predicting X2 4-1
4.2 Desired Monitoring Data and Accuracies 4-2
4.2.1 Preferred Salinity Monitoring Design 4-3
4.2.2 Flow Monitoring Design 4-4
4.3 Summary 4-6
5 USGS Monitoring Proposal 5-1
5.1 Overview 5-2
5.2 Instrumentation and Deployment Details 5-2
5.2.1 Option 1- Monitor X2 and the ETM with Greater Precision and Capture
the Physics 5-2
5.2.2 Option 2 - Monitor X2 and the ETM with Greater Precision Only 5-3
5.2.3 Option 3 - Monitor X2 with Greater Precision Only 5-3
5.3 Cost Estimates Developed by USGS 5-4
6 Report Summary and Considerations for Monitoring System Improvement 6-1
6.1 Challenges in measuring near-bottom salinity 6-1
6.2 Station Location Options 6-2
6.3 Technology and Methods to Consider 6-2
6.4 Changes to Data Analysis Methods 6-3
6.5 Summary 6-3
7 References 7-1
Appendices
APPENDIX A:
Salinity / Conductivity Instrumentation Equipment Overview, Comparison and Manufacturers'
Specifications
APPENDIX B:
Flow Measurement Instrumentation Equipment Overview, Comparison and Manufacturers'
Specifications
APPENDIX C:
Equipment Deployment Options
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List of Figures
Figure 1-1 Stations with Records of Salinity Data in the North San Francisco Bay and
western Delta 1-3
Figure 2-1 A Conceptual Model of Gravitational Circulation, Estuarine Turbidity
Maximum (ETM) Formation, Salinity Stratification and Intrusion in the North
Bay and Western Delta 2-4
Figure 3-1 Bay Delta Continuous Monitoring Sites (Reproduced from Jabusch and
Gilbreath, 2009) 3-3
Figure 3-2 EMP's Real time Monitoring Stations 3-4
Figure 3-3 USGS Continuous Monitoring Stations in SF Bay (Blue) and the Bay Delta
(Green) 3-6
Figure 3-4 Typical monitoring installation, San Francisco Bay study (Buchanan 2014) 3-8
Figure 3-5 Example of USGS WQ Monitoring Station (using YSI 6920V2 internal
logging Sonde) 3-8
Figure 5-1 USGS Locations of Proposed Temperature, Salinity and Turbidity Monitoring
Equipment. All of the stations proposed are new (circle icons), except at
MAL(s), RIO and JPT (square icons), which are long-term monitoring
stations run by the DWR-RTM. (Burau 2017) 5-5
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List of Tables
Table 2-1 Recalibration of KM-equation with Monthly Interpolated X2s. Coefficient
Columns are Displayed as Estimate +/- One Standard Error. (SAC=
Sacramento River Branch; SJR = San Joaquin River Branch) 2-9
Table 2-2 X2 auto-regressive equations and RMS errors. (Adapted from M.
MacWillams presentation with citations revised and all equations converted
to units of flow in cfs). Table courtesy of Reed et al., 2014: Panel Summary
Report on the State Water Resources Control Board's Workshop on Delta
outflows and Related Stressors, May 5, 2014 2-10
Table 5-1 Cost Estimates of Three Monitoring Advancement Plans/Options 5-4
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1 Introduction
1.1 Purpose
The purpose of this report is to evaluate the need for and benefits of improving the
monitoring network that supports the Delta outflow objective. The US Environmental
Protection Agency (EPA) identified strengthening water quality standards and advancing
regional water quality monitoring programs as the two highest priority actions that EPA
could take to accelerate restoration of aquatic life and ensure a reliable water supply for
cities and farms in the San Francisco Estuary watershed (EPA Action Plan 2012).
California is in the process of updating federal and state water quality standards for the San
Francisco Estuary and the upper watershed. The Delta outflow objective is one of several
water quality standards in the San Francisco Bay/Sacramento-San Joaquin Delta Estuary
Water Quality Control Plan. The State Water Board is evaluating changes to the Delta
outflow objective (and several other objectives) in an effort to improve protection of
aquatic life. It is timely and useful to consider changes to the monitoring network as the
state considers updating and implementing the Delta outflow objective and other standards.
This report evaluates the cost and utility of adding coupled surface and near-bottom salinity
monitors along the axis of the San Francisco Estuary and the types of equipment and
approximate costs of this additional monitoring effort. Technological advances in
monitoring equipment have occurred since the Delta outflow objective was first
implemented in the 1990s; however, the monitoring network has not changed substantially
in more than twenty years. Modern instruments and higher spatial resolution can greatly
increase the precision and utility of monitoring data for determining compliance with
standards, advancing forecasting tools, and evaluating the effectiveness of water quality
standards in protecting water quality for aquatic life and water deliveries.
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1.2 Report Goals
1. Summarize knowledge of the salt field and freshwater outflow in San Francisco
Estuary and identify the data limitations.
2. Evaluate the feasibility of adding coupled surface and near-bottom salinity
measurements in the estuary to ongoing continuous monitoring programs.
3. Evaluate the feasibility of improving flow measurements enough to accurately
measure and calculate net freshwater outflow with existing technology.
4. Describe an improved salinity monitoring design and methods for incorporating it
into existing monitoring programs.
5. Estimate the cost of improving the existing monitoring system to measure coupled
surface and near-bottom salinity and to improve flow measurements.
In the following chapters, we summarize existing scientific and regulatory knowledge of
the salinity field in San Francisco Estuary, including the current regulatory framework and
reporting requirements (Chapter 2). An overview of the monitoring currently being done
is presented in Chapter 3. We identify desired improvements in the monitoring network
(Chapter 4) based on our understanding of salinity behavior in the estuary. And, we provide
an estimate of installation, operation, and maintenance costs for a coupled, surface and
near-bottom salinity monitoring array based on preliminary plans developed by the US
Geological Survey (USGS) (Chapter 5). Considerations for monitoring system design,
going beyond the preliminary USGS proposal, are presented in Chapter 6.
A comprehensive evaluation of costs and performance of available instruments for
monitoring salinity and flow is reported in Appendix A and B. Conceptual ideas for
potential deployment options, based on our prior experience in other water bodies, are
provided in Appendix C. While the instrument selection in the estuary may have been
narrowed down based on ongoing or planned efforts, as described in this document, the
information in the Appendices provides a reference for cost and performance comparison
for other instruments that are available commercially at this time.
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2 Flow and Salinity in San Francisco Estuary
2.1 Behavior of the Salt Field and Delta Outflow in San
Francisco Estuary
Freshwater inflows into SF Estuary vary strongly by season and by year, creating a time-
varying salinity gradient that has been related to the abundance of various marine,
estuarine, and freshwater fish species. The horizontal and vertical salinity profile in the
northern part of San Francisco Estuary—including San Francisco, San Pablo, Richardson,
Suisun and Grizzly Bays, Suisun Marsh, and the Sacramento-San Joaquin River Delta—is
primarily affected by freshwater flows from the contributing watershed and exchange with
ocean water through Golden Gate. Secondary drivers include wind and spring-neap tidal
variations. The actual salinity distribution in time and space is a function of these drivers
and the complex bathymetry of the estuary. Salinity is managed at key locations in the
northern part of the estuary to support multiple aquatic species and drinking water and
irrigation water uses.
The movements of the salt field and Delta outflow are coupled. When Delta outflow
increases, the salt field moves downstream in response, primarily due to advection by the
net flow. In other words, saltier water is pushed toward the sea by freshwater flow from
tributaries, a relatively straightforward process. However, when freshwater flows from
tributaries decrease and Delta outflow decreases, the salt field moves upstream, but, in this
case, the physical processes are more complex and depend on gradients in the salt field
interacting with the tidal currents and the geometry of the estuary.
Large changes in the position of the salt field occur in the winter in response to the
uncontrolled run-off events associated with wintertime storms. During low flow periods
(typically late spring through early winter), the salt field remains relatively stable because
Central Valley Project (CVP) and State Water Project (SWP) operators adjust reservoir
releases and/or export rates to maintain salinity standards at Jersey Point, and occasionally
at Emmaton (Figure 1-1). During these periods, project operators make adjustments in
Delta outflow primarily in response to spring/neap tidal variations in the strength of salinity
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intrusion, and occasionally to make adjustments for atmospheric pressure changes and
sustained westerly winds.
Downstream movements of the salt field can be relatively quick in response to an increase
in Delta outflow, following an advective timescale. Upstream movements of the salt field
are often slower depending on the suite of dispersive processes that are primarily controlled
by the position and structure of the salt field in the estuary and the timing of tidal forces
(spring/neap cycle) relative to when an outflow event occurred.
The horizontal salinity gradient is the primary driver of salinity intrusion. The horizontal
salinity gradient is the spatial change in salinity along the axis of the estuary, which varies
from oceanic salinity (roughly 35 psu) near the Golden Gate Bridge to fresh water (zero)
at Rio Vista on the Sacramento River. One of the best ways of thinking about the horizontal
salinity gradient is to think of it as a spring. Compression of the horizontal salinity gradient
occurs when Delta outflow increases, expansion of the gradient occurs when Delta outflow
decreases. Compression of the horizontal salinity gradient increases the rate of salinity
intrusion through a host of mechanisms that include gravitational circulation (tidally
averaged two-layer exchange flow that is driven by a horizontal density gradient created
by the difference in salty water in the bay and fresh water), tides, and winds. Dilation, or
relaxation of the spring reduces the rate of salinity intrusion due to the same mechanisms.
The greater the increase in Delta outflow, the farther the salt field is pushed downstream
and the more compressed the spring becomes. For example, when the salt field is pushed
downstream of the Benicia Bridge, it moves back very rapidly, because: (1) the salt field
is highly compressed when it is seaward of the Benicia Bridge, and (2) Carquinez Straight
is deep, which enhances gravitational circulation. Once the salt field is fully in Suisun Bay
or the western Delta, the horizontal salinity gradient is relaxed and the depth in the channels
is shallower.
The movements of the salt field can appear complicated, especially given the complexities
of the bathymetry in Suisun Bay and in the western Delta. However, for the most part, we
understand how the salt field works, at least at the time and space scales necessary for the
proposed work. In this regard, the basic physics of the process is relatively mature. Unlike
Delta outflow, the position of salt field can be accurately measured, provided the
monitoring program has sufficient spatial resolution.
A conceptual model of freshwater/saltwater mixing in San Francisco Estuary is shown in
Figure 2-1. Seaward of the approximate 2 parts per thousand isohaline (X2), both
barotropic (water surface slope driven) and baroclinic pressure gradients (pressure
differences due to a density difference between salt and freshwater) exist. The baroclinic
pressure gradient is created in estuaries by the horizontal salinity gradient which drives
periodic, density driven circulation cells on a tidal timescale. This can be visualized as
upstream flow at the bed and a downstream flow at the surface. These density-driven
circulation cells are strongest near slack water (a short period before the reversal of tidal
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direction in which water is not moving in either direction), especially during neap tides
when vertical mixing is weakest.
The current framework of sampling stations does not extend far enough down-estuary and
monitoring locations are too far apart to capture the tidal dynamics that determine the
position of X2. Pulses of density driven 2-layer exchange flows typically occur near slack
water twice a day which create varying degrees of periodic stratification throughout the
brackish water regions of the estuary. Importantly, the salt field, including its vertical and
horizontal structure and the density-driven two-layer exchange flow (when it is occurring
near slack water) are all advected by the tidal currents long distances with each tide, a
distance known as the tidal excursion. In Suisun Bay the tidal excursion is on the order of
21 km (roughly the length of Suisun Bay), and 13 km in the western Delta. This two-layer
exchange flow occurs downstream of the 2 psu isohaline in a reference frame which
traverses up to 21 km every ~6 hours. Expanding the monitoring network by adding
downstream monitoring stations and increasing the resolution of monitoring stations along
the axis of the estuary will generate measurement data that capture tidal dynamics and are
then used to derive equations that predict X2 and other hydrodynamic endpoints with
greater precision.
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Formation, Salinity Stratification and Intrusion in the North Bay and Western Delta.
2.2 Summary of Delta Outflow Objective and X2
The State Water Resources Control Board (State Water Board) sets water quality objectives
under the Porter-Cologne Water Quality Control Act and delegated authority of the Clean
Water Act to protect beneficial uses of water in the SF Estuary. The Delta outflow objective
was adopted by the State Water Board and approved by USEPA in 1995 to protect resident
and migratory fish that use the SF Estuary. The relationship between fish species
abundance and X2, the near-bottom 2 parts per thousand (ppt.1) salinity isohaline as
described in Jassby et al. (1995), is the scientific foundation of the flow and salinity-based
Delta outflow objective which has controlled regulation of springtime freshwater flows in
the estuary over the past two decades. During that time scientific research has continued to
evaluate the relationships between salinity and biology (Feyrer et al., 2007, 2011;
Kimmerer et al., 2009) and between salinity and flow (e.g., Monismith et al., 2002; Gross
et al., 1999; MacWilliams et al., 2015). Nevertheless, the basic approach and tools for
'In current usage, ppt and practical salinity units (psu) are equivalent.
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measuring, managing, and calculating salinity and freshwater flow outlined in 1995 are
still in use.
The Delta outflow objective includes flow and salinity targets for compliance, dependent
on location and seasonal hydrology and precipitation. Delta outflow targets of 7,100 cubic
feet per second (cfs), 11,400 cfs, and 29,200 cfs are established at specific compliance
locations of Collinsville, Chipps Island, and Port Chicago, respectively (Figure 1-1). These
compliance locations correspond to X2 values of approximately 80 km, 75km, and 65 km
respectively. Compliance with the flow objective is determined using the Net Delta outflow
Index (NDOI), a tidally-averaged, daily estimate and not a direct observation. The NDOI
has large, known inaccuracies at low freshwater flows.
A surface salinity target in the form of specific conductance of 2.64 mmhos/cm2 is
established at Collinsville, Chipps Island, and Port Chicago to approximate a near-bottom
salinity of 2 ppt or psu (3.8 mmhos/cm) at 80 km, 75 km, and 65 km from the Golden Gate
Bridge respectively. A constant factor is used at all three compliance locations to represent
vertical salinity stratification (fixed ratio between surface and bottom salinity), yet we
know that salinity stratification varies significantly with the tides, the spring/neap cycle
and the position of the salt field (Stacey et al. 2010; MacWilliams et al., 2015). Near-
bottom salinity measurements are not routinely measured, and are not part of the
compliance calculation.
2.3 Estimating, Measuring, and Error in Delta outflow
Delta outflow on a daily average basis is reported as the Net Delta outflow Index (NDOI).
The NDOI is calculated as the sum of all Delta inflows minus exports through aqueducts,
and minus the net channel depletion in the Delta, which accounts for consumptive use and
precipitation. Inflows are measured at five locations: Sacramento, San Joaquin River,
Cosumnes and Mokelumne Rivers, and the Yolo Bypass; with a term for other
miscellaneous flows. Exports are summed for four aqueducts that transfer water outside
the Delta: CVP, SWP, North Bay Aqueduct, and the Contra Costa Canal. The NDOI is a
daily, tidally-averaged estimate and not a direct observation. Actual Delta flows change
rapidly over the course of tidal cycle, and this tidal variation is not part of NDOI.
Moreover, variations in the net flow and dispersive mixing associated with the spring/neap
cycle and changes in atmospheric pressure can significantly alter the position of the salt
field.
Forecasting methods for flow targets contain errors which result in small to large
differences between predicted and actual ecological conditions and water supply export
volumes. For example, comparisons of measured Net Delta outflow using USGS acoustic
Doppler measuring instruments at four locations near the confluence of the Sacramento
2 Note that continuous salinity measurements in modern sensors are obtained as electrical conductivity, and reported
at a standard temperature of 25° C, termed specific conductance. Electrical conductivity and specific conductance
are typically reported units of millimhos/cm or mmhos/cm.
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and San Joaquin Rivers to estimates of NDOI show significant differences because both
methods are imprecise, for different reasons. For example, NDOI estimates are based on a
mass balance approach, where all of the measured inflows and outflows into and out of the
Delta are summed. Therefore, NDOI includes the sum of all the inaccuracies in the
measurements that make up the NDOI estimate. Moreover, net Delta island consumptive
use is an estimate based on cropping patterns. When inflows and exports are both high, the
net Delta island consumptive use is a relatively small component of the NDOI estimate.
However, when inflows and exports are low, the net Delta island consumptive use can
make up a significant portion of the NDOI estimate, and errors in the estimate translate to
errors in NDOI.
Measuring net Delta outflow with the USGS acoustic Doppler instruments is also
challenging at low Delta outflows. Measuring net Delta outflow in the field is characterized
by a classic signal to noise problem. The tidal signals are orders of magnitude greater than
the net flows. Daily peak tidal flows in the western Delta can be on the order of 150,000
cubic feet per second (cfs) (Department of Water Resources, 2016) while net freshwater
flow in dry periods is often 5,000 cfs or less and sometimes negative during strong spring
tides or during prolonged wind events. The measured net Delta outflow is actually a
calculation including the sum of the tidal average of the measured data at four locations
using a tidal filter (Walters, 1984). Tidal filters basically subtract the flood and ebb
discharges to compute the net. Therefore, the combined tidal discharge at four stations must
be measured with an accuracy of < 3% (=100*5,000/150,000) to compute Delta outflow
when the outflow is 5,000 cfs or lower. The technology to measure Delta outflow to this
level of accuracy does not exist. Not surprisingly, given the imprecision in both estimates
of net Delta outflow (measured and NDOI), analysis by Monismith shows that there is no
relationship between these estimates when Delta outflows are less than 10,000 cfs
(Monismith, personal communication). A similar analysis by the Department of Water
Resources (2016) indicates a significant difference between NDOI and measured Delta
outflow.
2.4 Estimating, Measuring, and Error in Salinity and the X2
ISOHALINE
X2 is computed by interpolation from salinity at fixed stations and using different
predictive equations that are primarily driven by flow history. Estimates of X2 are based
on surface salinity measurements because near-bottom salinity is not routinely measured.
The reason bottom salinity is the ecological variable of choice over surface water
measurements is that in the brackish estuarine environment salinity stratification associated
with gravitational circulation fluctuates with the tides (weak during the tidal current
magnitudes and strong during near slack water periods) can make surface measurements
problematic. Moreover, the location of the estuarine turbidity maximum is more closely
physically associated with the position of the 2 psu isohaline (Arthur and Ball, 1978; Burau
et.al., 1998) because X2 is roughly the location where the strength of the horizontal salinity
gradient becomes dynamically insignificant.
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The original analysis supporting the use of X2 as an estuarine water quality standard
assumed a constant vertical salinity gradient of 0.24 ppt such that a bottom salinity of 2 ppt
corresponded to an average surface salinity value of 1.76 ppt; this was based on a limited
amount of observed data at the surface and bottom. For regulatory purposes, this bottom
salinity was assumed to be equivalent to a surface electrical conductance (standardized to
25 °C) of 2.64 mmhos/cm or mS/cm (2,640 |a,S/cm). Specifically, Jassby et al. (1995)
wrote:
"Where the bottom salinity was near 2%o (specifically, between 1.5 and 2.5%o), the
difference between bottom and surface salinity was unrelated to flow, except at very high
flow. The median difference (bottom minus surface) was 0.24±0.06 (mean and 95%
confidence interval), implying that a bottom salinity of 2%o; corresponded to a surface
salinity of 1.76%o. "
Since the development of the original regulation, X2 has been characterized using surface
salinity measurements and an equation using a constant ratio between the bottom and
surface salinity, as in the above quote. However, the exact value of the ratio is different in
other X2 calculation approaches (Reed et al., 2014).
Bottom salinity data in the estuary are limited because of the challenges of supporting
continuous long-term sensors at depth, related to maintenance, access, and fouling by near
bottom sediments. A small number of stations have been monitored at the bottom, but they
are usually near shore. Nearshore bottom salinity measurements often more closely
represent the near surface measurements because shallow regions do not support
gravitational circulation and salinity stratification. Moreover, most of the salt flux
associated with salinity intrusion and brackish water habitats occurs at depth, in the
shipping channels in Suisun Bay (Burau et al., 1998, 1999; Stacey et al. 2010). Despite the
challenges, measurement of near-bottom salinity is consistent with the X2 standard and
aquatic habitat knowledge that supports the Delta outflow objective.
2.4.1 X2 Model-based Calculations
Over the past two decades, various modeling frameworks (equations or sets of equations)
have been applied to the prediction of the X2 position and of the salinity patterns in the
Delta and San Francisco Bay, ranging from simple statistical models (a log-linear equation)
to complex three-dimensional hydrodynamic models. A widely used statistical approach is
the autoregressive equation between Delta outflow and X2 position, termed the K-M model
(Kimmerer and Monismith, 1992; Jassby et al., 1995). This equation was calibrated using
salinity data in the Bay and Delta from October 1967 to November 1991, the most complete
data set available at the time of publication. The monthly flow-X2 relationship (Kimmerer
and Monismith, 1992) was expressed in the original document as:
X2(t) = 122.2 + 0.328X2(t-l) -17.65 logio(Q0ut(t)) Eq. 1
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where Qout is the mean monthly Delta outflow in terms of cubic feet per second (cfs) and
X2(t-1) is the previous month isohaline position expressed as km from Golden Gate.
A recent review and evaluation, including discussion with the original authors, of the above
equation being presented with different coefficients, suggests a slightly modified set of
coefficients (Reed et al., 2014):
X2(t) = 10.16 + 0.945X2(t-l) -1.487 logio(Qout(t)) Eq. 2
Both equations are in units of cfs for flow. The standard error computed for Eq. 2 is 6.11 km
(Reed et al., 2014, based on a presentation provided to the Delta outflows and Related
Stressors Panel by Michael MacWilliams). Several variations of the original equation, with
different coefficients, have been reported, as summarized in Muller-Solger (2012).
Most available formulations use a limited subset of the data that are available today. For
example, Mueller-Solger (2012) reported that even if one retained the original formulation
of the X2 equation, an additional 20 years of data have become available (Jassby et al.,
1995 used data from 1967-1991).
In more recent work (Roy et al., 2014), the Jassby et al. (1995) model was recalibrated and
the constants in the autoregressive equation (A, B, and C) were obtained:
X2(t) = A + B X2(t-1) - C log(Qout(t)),
This was done for each river branch using data for several different time periods:
• the entire record of observed salinity data at fixed stations (Hutton et al., 2015),
October 1921 to September 2012;
• the period with only historical grab sample data, October 1921 to June 1964;
• the period with only continuous data, July 1971 to September 2012; and,
• the period for which the original estimate of Kimmerer and Monismith was
computed, October 1967 to November 1991.
Results are shown in Table 2-1. Note that the logarithmic term in the K-M equation
precludes its use for negative outflows that occurred during some periods of the historical
record. In all cases, equations that are broadly similar to the original K-M equation provide
reasonable fits, with coefficients that are approximately in the same range for the flow
term.
The flow-X2 equation has also been proposed using an exponent form of the Qout term,
rather than the logarithm, using the same surface salinity dataset as in the original analysis
(Monismith et al., 2002), as well as with other coefficients for flow added to the basic
structure of Eq 2 (MacWilliams et al., 2015). A review of the equations incorporated in
Reed et al. (2014) is reproduced in Table 2-2.
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In addition, there are several published one-, two- and three-dimensional numerical model
applications for salinity in the region, each of which has been applied for research or to
understand mechanistically the effects of specific system changes, such as changes in
inflows and Delta operations or external effects such as sea level rise (e.g., Mierzwa and
Anderson, 2002; Anderson etal., 2008; Gross etal., 2007,2010; MacWilliams etal., 2015).
Table 2-1
Recalibration of KM-equation with Monthly Interpolated X2s.
Coefficient Columns are Displayed as Estimate +/- One Standard Error. (SAC= Sacramento River
Branch; SJR = San Joaquin River Branch)
River
Period
of Regression
r2
Standard
Error of
Regression
(km)
A
B
C
SAC
10/01/1921 to
09/01/2012
0.930
3.51
114. +/-1.80
0.418+/-0.0106
-17.3 +/-0.291
SAC
10/01/1921 to
06/01/1964
0.923
3.95
112. +/- 2.65
0.432 +/-0.0158
-17.2 +/-0.439
SAC
07/01/1971 to
09/01/2012
0.939
3.07
119. +/- 2.63
0.392 +/-0.0153
-17.9 +/-0.418
SAC
10/01/1967 to
11/01/1991
(K-M period, as
used in Jassby et
al., 1995)
0.948
2.79
110. +/- 3.36
0.419+/-0.0198
-16.2 +/-0.517
SJR
10/01/1921 to
09/01/2012
0.923
3.92
119. +/-1.92
0.425 +/-0.0107
-18.5 +/-0.321
SJR
10/01/1921 to
06/01/1964
0.912
4.57
119. +/-2.91
0.433 +/-0.0162
-18.8 +/-0.506
SJR
07/01/1971 to
09/01/2012
0.935
3.31
120. +/- 2.75
0.410+/-0.0155
-18.4 +/-0.445
SJR
10/01/1967 to
11/01/1991
(K-M period, as
used in Jassby et
al., 1995)
0.946
3.00
110. +/- 3.52
0.439 +/- 0.0201
-16.5 +/-0.551
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Table 2-2
X2 auto-regressive equations and RMS errors. (Adapted from M. MacWillams presentation with
citations revised and all equations converted to units of flow in cfs). Table courtesy of Reed et al.,
2014: Panel Summary Report on the State Water Resources Control Board's Workshop on Delta
outflows and Related Stressors, May 5, 2014.
Citation
Autoregressive Equation
(X,inkm, Qinefs)
RMS
Error
(km)'
1.) Schubel et al (1993),
Appendix A. (DAYFLOW)
X/n = 1016 - 0945 X/r-l > - 1 487 log fQ jtu
611
2. (Jassby fl )L (1995)
(not plotted in Figure 2)
3.) Jassby eq. as cited by
Mon< smith et al (2002)
4.) Momsmnthet al.
(2002)
5.) Gross et al. (2010)
6.) MacWilliamsct al. (In
review) with flow-
dependent a
1 RMSt cxi diMercncei with X2.
XJt> = 103* 094? ¦ A'/M> - 1,5 log,, (Q .W)
XJti -1376+0945 • A'/M t - 23 log (Q
\'M) = 0.919 X./tAj * 22 U Q .w 1,1
X/n = 0j910 > * 3616
X.lt) - a'XJt-l) * (\-a) MA9 Q jt)
ut>c
7.33
9.22
7,47
5-31
Constanta
4.17
Vanablca
3.10
I for 4/94 to 4/97
2.4.2 X2 Calculation by Interpolation
In 2007, the California Data Exchange Center (CDEC) started reporting the X2 value as a
linear interpolation for the 2.64 mS/cm EC isohaline location from the following four
stations (with distances from Golden Gate): Martinez (56 km), Port Chicago (64 km),
Chipps Island (74 km) and Collinsville (81 km). By this definition, the value is not reported
when the X2 falls outside the 56-81 km range. This is available online at:
http://cdec.water.ca.gov/cgi-progs/stationInfo7station id=CX2. Each of these 4
monitoring stations has upper and lower measuring probes, although the lower probes are
not currently used for X2 determination. This is because they have shorter records and
generally do not measure salinity at the bottom along the center-line of the estuary, but
rather at a location corresponding to the surface salinity observation point (Reed et al.,
2014). Importantly, the surface salinity data are used as a surrogate for bottom salinity with
a constant difference of 0.64 (Reed et al., 2014, based on M. MacWilliams, workshop
presentation), which is different from the value of 0.24 used by Jassby et al. (1995) and
discussed in the introduction of this chapter.
Another related approach is to use log-linear interpolation, as employed in the original
Jassby et al. (1995) approach. In this approach, log salinity versus distance interpolation is
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performed across two stations that bound a specific isohaline level, i.e., for the X2 or 2.64
mS/cm isohaline. This can be generalized to any position within the estuary, and the
interpolated X2 can be outside of the 56-81 km range, which does occur frequently.
Similar to net Delta outflow, measurement and prediction methods describing the estuarine
salinity gradient and near-bottom salinity are characterized by significant error. One reason
for the error is poor spatial resolution in the data (measurements separated by at least 10
km) because some of the dynamics that determine the position of the salt field occur at
spatial scales than are less than the distance between the salinity monitoring stations. A
second reason is that bottom salinity is not directly measured, but estimated as a constant
factor of the surface salinity, which is a coarse simplification of the underlying process.
Large water costs may occur due to insufficient monitoring resolution and subsequent large
errors in predictive equations. Equations to estimate X2 described above have standard
errors that range from 3 to 9 km. The difference in the estimate for X2 could result in
substantially different water costs to municipal and agricultural water users and represent
a significantly different index of the aquatic habitat available for resident and migratory
fish species for a given X2. For example, if an X2 equation predicts a value of 75 km, but
X2 is actually 70 km (as measured near the bottom), more freshwater would need to be
released from reservoirs than necessary or export pumping would be restricted more than
necessary to meet the 75 km requirement. The subsequent water cost to water users is
approximately 300,000 acre feet per month (Schubel Report, 1993, Appendix A, table 2,
page A-10). Alternatively, if an X2 equation predicts a value of 70 km, but X2 is actually
75 km, then the aquatic habitat loses approximately 300,000 acre feet of freshwater per
month and more importantly the habitat and abundance benefits associated with an X2
location of 70 km over 75 km in the estuary.
These well-known deficiencies in salinity and flow measurement and prediction methods
led to a Delta Stewardship Council panel suggestion of installing salinity monitoring
instruments at "both the surface and bottom of the water column on channel markers at
regular intervals along the axis of the estuary," as a method for generating new field data
that can be used to increase the precision of equations that predict salinity and X2 (Reed et
al., 2014). Instruments that directly measure near-bottom salinity are now widely available.
In addition, new technology is in development to measure a continuous vertical salinity
profile in the water column at a given location and measuring multiple water quality
elements at these locations will provide important habitat quality information.
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3 Existing Monitoring Network
The Delta outflow objective, along with other flow and salinity objectives, is implemented
by the State Water Board in a water rights decision issued to the Department of Water
Resources (DWR) and U.S. Bureau of Reclamation (USBR) for the operation of the State
Water Project (SWP) and the Central Valley Project (CVP) water delivery projects. Water
quality standards (objectives) were last amended under the 1995 Water Quality Control
Plan and Water Right Decision 1641 (D-1641) established in 1999. The SWP and CVP are
currently operated to comply with the monitoring and reporting requirements described in
D-1641. D-1641 requires both agencies to conduct a comprehensive environmental
monitoring program to determine compliance with water quality standards and also to
submit an annual report to SWRCB discussing data collected.
Continuous water quality monitoring is one element of the Bay-Delta Monitoring and
Analysis Section (EMP) conducted by DWR and USBR with support from the USGS under
the Interagency Ecological Program (IEP). The overall objective of the water quality
monitoring program is to provide information for water resource management in
compliance with flow-related water quality standards set forth in the Water Right Decision
1641 described above. These decisions permit the USBR and DWR to deliver water by
operating the CVP and the SWP. In return, the two agencies are required to monitor the
effects of diversions and flow manipulations resulting from project operations and ensure
the compliance with existing water quality standards and protection of the most sensitive
beneficial uses.
This chapter presents a general description of the ongoing monitoring programs and the
different approaches for computing X2 that are based on these programs. Monitoring
programs in place include:
• Continuous Multi-parameter Monitoring (IEP Environmental Monitoring
Program), operated by the Department of Water Resources
• Continuous Recorder Sites, operated by the Department of Water Resources and
the U.S. Bureau of Reclamation
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• Delta-Mendota Canal Water Quality Monitoring Program, operated by the U.S.
Bureau of Reclamation
• Municipal Water Quality Investigations (real-time sampling), operated by the
Department of Water Resources
• State Water Project Water Quality Monitoring (continuous sites), operated by the
Department of Water Resources
Continuous monitoring focuses mainly on flow and general water quality characteristics
such as salinity, temperature, and turbidity with limited coverage of a few other parameters
such as chlorophyll fluorescence, organic carbon, and nutrients (Jabusch and Gilbreath,
2009). An overview of the continuous monitoring sites is shown in Figure 3-1.
3.1 Interagency Ecological Program - Environmental
Monitoring Program
The DWR Environmental Real Time Monitoring (RTM) and Support section monitors
Delta water at nine continuous water quality monitoring stations from Martinez in Suisun
Bay to Hood on the Sacramento River and Vernalis on the San Joaquin River (Figure 3-2).
DWR-RTM water quality instruments are all manufactured by YSI. The instruments
presently in use include the YSI 6600 and EX02. The YSI 6000 is deployed 3 feet below
water surface, and the EXOl is deployed the 5 feet above river bottom. Bottom salinity
(reported as specific conductance) is currently collected at only three locations, Martinez,
Mallard Island, and Antioch, of the nine multi-parameter stations in support of X2
monitoring. Bottom specific conductance is also collected by USBR at 2 sites, Collinsville
and Antioch, within the Sacramento-San Joaquin Delta. RTM is currently in process of
upgrading from the YSI 6600 series to the new YSI EXO platform with improved
calibration and related performance characteristics (instrument details are presented in
Appendix A.
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EMP's Real Time Data-
Active Stations
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The calibration intervals vary depending on the parameter being measured and the type of
the instrument being used. Handheld devices are used as a way to cross-check the data
collected at monitoring stations. All calibration is done in the lab with the exception of
dissolved oxygen (DO).
Data are transmitted to State Water Project operations via wireless telemetry real-time to
provide information on Delta conditions. Publically available data are posted to the CA
DWR Real Time Monitoring web site (http://www.water.ca.gov/rtm) and the California
Data Exchange Center (CDEC) web site (http://cdec.water.ca.gov).
3.2 US Geological Survey (USGS) Monitoring Network
The San Francisco Bay Hydrodynamics project, managed by USGS California Water
Science Center (CAWSC), conducts hydrodynamic transport investigations in the Bay and
Bay Delta, with financial support from the DWR and USBR and in collaboration with a
broad coalition of state and federal agencies (SWRCB, CDFW, and USFWS).
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The USGS CAWSC has standardized flow and water quality monitoring methods in the
Bay and Delta for data collection instrumentation, equipment configuration, telemetry
protocols and data QC and reporting. This approach allows multiple individuals to work
on station servicing and maintenance without the need for site specific knowledge of any
particular setup or instrument configuration. By using standard methods, it is relatively
easy for USGS to add additional monitoring stations, with identical equipment
configurations, while only incrementally increasing annual maintenance costs for the
monitoring network.
The USGS owns multiple vessels configured for field measurements and maintenance of
the fixed monitoring stations. Each vessel is stocked with equipment spares, sampling
equipment and a permanently installed Acoustic Doppler Current Profiler (ADCP) for flow
monitoring and to update index ratings of installed discharge monitoring stations.
The USGS maintains a network of 38 flow and water quality stations across the Delta
(Figure 3-3). This project began measuring the flows in the Delta in 1987. The network
has been expanding since then, and now is comprised of 21 continuously operating flow
stations and 32 continuous water quality monitoring stations. Plans are to expand the flow
measurement network from 21 to 29 stations, with additional stations in the Deep Water
Ship Channel and Liberty Island Cache Slough region.
(http://ca.watcr.usgs. gov/proi ects/sf hydrodynamics .html). Collection of salinity,
temperature, and water level time series began in 1988; collection of turbidity and
suspended sediment concentration (SSC) time series began in 1991; and collection of
dissolved oxygen time series began in 2012 (Buchanan, 2014).
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3.2.1Water Quality Monitoring
Continuous water-quality measurements are collected at stations throughout the San
Francisco Bay and Delta using multi-parameter water quality sondes. The sondes are
usually deployed in the water by suspension from a stainless-steel cable anchored to the
bottom (Figure 3-4 and Figure 3-5) or in plastic pipes strapped to pilings. The sondes are
equipped with sensors that measure water level (pressure sensor), temperature, specific
conductance, turbidity (optical), Chlorophyll-a (optical), fluorescent dissolved organic
matter (FDOM, optical) and dissolved oxygen. Data are recorded every 15 minutes and are
retrieved either real time via cellular telemetry or by manual download during routine
station visits
(http://ca.water.usgs.gov/projects/baydelta/methods.html).
Biological activity and growth (biofouling) interfere with sensor readings, requiring
regular servicing intervals and that data affected by biofouling to be corrected or deleted.
Biofouling increases with time and generally is greatest during spring and summer; the
degree of biofouling is site dependent, causing data return to vary among stations.
Biofouling is mitigated by routine sensor cleaning and anti-fouling sensor equipment such
as wipers for optical sensors. Self-cleaning sensors have proven to reduce data loss only in
relatively fresh water because they are ineffective when fouling is excessive and they are
prone to leak and malfunction in saltier water (Buchanan and Ruhl 2001), though wiper
technology has greatly improved in the last 5 years. Every 2-5 weeks, each station is visited
to clean, calibrate, and download the instruments. The CAWSC hydrodynamics project
checks their data every day and sends out crews on an as needed basis when sensors are
fouled. Sensor performance is also ensured by comparing sensor output with nearby
stations in real-time and known values; such comparison is used to identify sensor drift,
calibration errors, or malfunction. For example, for temperature, sensor output is compared
to that from a NIST traceable thermistor. For specific conductance and turbidity, sensor
output is checked against and, if needed, calibrated to, solutions of known value
(standards). For dissolved oxygen, sensor output is checked in water-saturated air.
Water samples are collected from the same depth as the sensor to calibrate the turbidity
data to the suspended-sediment concentrations. For stations that compute water discharge
and cross-sectionally averaged SSC, water samples are collected periodically at points
across the channel by using the equal-discharge-increment method, and velocity is
measured by ADCP.
Specific conductance (reported in micro-Siemens per centimeter at 25° Celsius) and water
temperature (reported in degrees Celsius) have been measured by using a YSI, Inc.,
conductance/temperature sensors. Two types of optical sensors have been used to monitor
turbidity: the DTS-12, manufactured by Forest Technology Systems, and the model 6136,
manufactured by YSI, Inc. Dissolved oxygen has been measured by using the optical model
6150, manufactured by YSI, Inc.
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Figure 3-5 Example of USGS WQ Monitoring Station (using YSI 6920V2 internal logging Sonde)
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3.2.2 Flow (Discharge) Monitoring
The network is comprised of 21 continuously operating flow stations (Figure 3-3). These
stations measure flows in the Delta in channels as well as at Chipps Island.
(http://ca.water.usgs.gov/proiects/sf hydrodynamics.html). Discharge is calculated from
velocity data in a two-step process (Ruhl and Simpson, 2005). First, the cross-sectional
area of the channel is computed from measured water levels and the mean cross-sectional
velocity is computed on the basis of the measured index velocity. The discharge is
calculated as the product of the channel cross-sectional area and mean velocity.
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4 Desired Improvements in Salinity and Flow
Monitoring
4.1 Deficiencies in Existing Monitoring Data and for Predicting
X2
Given the importance of flow and salinity in the San Francisco Estuary, we are fortunate
to have an extensive long term record of salinity, spanning more than nine decades (data
summarized in Hutton et al., 2015). However, most of the historical salinity data in San
Francisco Bay are based on measurements made near the surface, and were originally
motivated by upstream withdrawals and salinity intrusion in the Delta (e.g., Department of
Public Works, 1931).
The present-day monitoring setup generally pre-dates the understanding of the role of near-
bottom salinity on estuarine physics and habitat and hence for outflow management. This
limitation was known at the time of the development of the X2 approach (Jassby et al.,
1995), and the method of predicting X2 used surface measured salinities as a surrogate for
bottom salinity with a correction factor. The top -bottom salinity difference was assumed
to be constant at 0.24 psu in Jassby et al (1995), but appears to have been modified to 0.64
psu in more recent reporting of X2 by DWR (Reed et al., 2014). The basis for the 0.64 psu
correction is not clearly documented in the literature. Given the dynamic nature of
stratification in partially mixed estuaries like San Francisco Bay (Stacey et al., 2010), the
assumption of a constant factor decreases the accuracy and precision of X2 time series
based on this assumption, although it may also give a systematic downstream bias to the
X2 estimate at very high flow rates when stratification can be significantly stronger than
0.24 psu (Monismith 2002). The development of X2 relationships has continued, with
different auto-regressive formulations in the literature (summarized in Reed et al., 2014
and as described in Chapter 4).
Some of the modified fits for X2 and flow appear to perform better than the original
formulation reported in the X2 publication (Jassby et al., 1995) because of the
incorporation of additional parameters, and/or with the use of a larger data set. In the final
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analysis, we do not expect the relationships to improve if they are based on surface
measurements taken at a small number of locations roughly 10 km apart. The current
monitoring is inadequate given our current understanding of the physics of salt transport in
this estuary (Burau et.al. 1998, 1999; Stacey et. al, 2010, Monismith et.al., 2002). More
detailed analysis of existing data, collected by the current monitoring network, may not
substantially improve the accuracy and predictive capability of these relationships.
Besides X2, another way of looking at the salinity management problem is to use the net
Delta outflow as a predictor for the position of the low salinity zone. However, recent work
shows that measurements of Delta outflow are problematic in strongly tidally-influenced
channels with weak net currents. For example, there are major differences between NDOI
estimates reported by DWR and direct measurements made by USGS using acoustic
Doppler (Monismith, 2015, personal communication; DWR, 2016).
Based on above discussion, it appears that a better estimate of X2, or the low salinity zone
in general, could be obtained by using a set of top and bottom salinity recorders that will
give us a more complete picture of the salt field, including along-channel variability in the
horizontal salinity gradient (or barotropic pressure gradient - the driver of gravitational
circulation and salinity intrusion) and vertical salinity gradient (as also noted by Monismith
et al. 2002 and Reed et al. 2014). This information would not be available retroactively, of
course, but methods could be developed to allow translation using surface salinity and flow
data that may permit more effective hind-casting of the bottom low salinity than the use of
constant difference between top and bottom salinity. Or, more simply, a relationship may
be possible that is not only based on improved measurements of the position of the salt
field but data on the dynamics of the salt field, such as the along-channel and internal
structure of the salt field, the spring/neap cycle, and possibly atmospheric pressure changes.
Analytical methods based on the physics of the salt field with data collected at the
appropriate resolution could then be developed to more accurately predict X2 which would
allow evaluation of the water costs under different scenarios with greater accuracy.
4.2 Desired Monitoring Data and Accuracies
While past experience and efficiency of existing methods and equipment are of significant
value, this effort is aimed at evaluating ways to improve the quality, accuracy, resolution,
and usefulness of the salinity and flow data without unnecessarily constraining ourselves
to existing practices and methods. Previous sections of the report outline and support the
primary reasons to improve the monitoring network. They include: 1) improve precision
of compliance methods for water quality standards, 2) improved ability to accurately
evaluate the effectiveness of water quality standards and management actions, 3) increase
precision of modeling equations used for forecasting and hindcasting, and 4) establishing
a framework for connecting hydrodynamic and biological measurements and exploring the
mechanistic drivers of biological outcomes in the estuary.
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It is important to evaluate how specific scientific and regulatory data requirements can be
better addressed through the use of existing state-of-the-art technology before constraining
the monitoring program design by choosing specific equipment, sampling methods, and
locations. In addition to more monitoring stations, we suggest reviewing newer
instrumentation, antifouling technology and deployment methods that might provide more
robust data, decrease data loss and maintenance costs and decrease the uncertainty in the
estimated X2 position. Key issues to be addressed are discussed below. In Chapter 4, we
present an alternative plan developed by Jon Burau of the USGS that addresses some, but
not all, of these issues.
4.2.1 Preferred Salinity Monitoring Design
An ideal monitoring network for X2 measurement and interpolation, and for the other
biologically relevant constituents would have the following design criteria:
Spatial Measurement Criteria:
• Monitoring locations spaced at intervals of no greater than 1/4 the tidal
excursion. Within reason, the closer the spacing, the more accurate the estimate
of X2. For example, a target spacing of 5 km has been proposed (Monismith,
2015, personal communication)
• Near-bottom (lm height) measurement of temperature, salinity, turbidity and DO
• Near-surface (lm depth) measurement of temperature, salinity, turbidity and DO
• Optional, full vertical water column profiles of all parameters, technology is still
in development
Temporal Measurement Criteria:
• Sampling interval not greater than 15 minutes
• Real-time reporting of near-bottom salinities (and additional water quality
parameters)
• Real-time reporting of near-surface salinities (and additional water quality
parameters)
• Daily reporting of tidally averaged near-bottom salinity
Instrumentation and Installation Requirements:
• At a minimum must measure conductivity, temperature
• Preferably measure conductivity, temperature depth, turbidity, DO
• Resistant to biological fouling for periods of at least 1 month and preferably
longer
• Deployment method must protect communication/power cables from debris
damage
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• Instrumentation must be easily recoverable from a surface structure or vessel (no
divers)
• Instrumentation must have sufficient batteries and PV panels to operate at
1 sample /15min
Data Quality Criteria:
• Daily QC of all real-time station data to highlight outliers and trigger site visit
• Greater than 95% of time with no data loss for instrument fouling/failure
• Monthly QC of all data sets before posting to USGS/ NWIS
4.2.2 Flow Monitoring Design
4.2.2.1 OVERVIEW AND BASIS FOR DATA NEED
Outflows in the San Francisco Estuary are strongly tidally influenced with large positive
(toward the ocean) and negative (toward inland) flows occurring over a tidal cycle. Tidal
flows are often much larger than the freshwater flows exiting the estuary (e.g., +/- 150,000
cfs for tidal flows, compared to freshwater outflows that are typically 10% of this value,
and often much lower in dry periods). For this reason, it is challenging to measure the
freshwater outflows directly, and there are programs that report data based on inflows into
the Delta at upstream non-tidally influenced locations (the DAYFLOW program used by
the Department of Water Resources; http://www.water.ca.gov/dayflow/). In reporting the
NDOI values of Delta freshwater outflow, besides the observed values of inflows and out-
of-Delta exports, DWR also makes an estimate of the in-Delta consumptive use, a quantity
that is not directly measured. When freshwater outflow is low, during the driest months of
the year and/or drought periods, the estimated consumptive use is often of the same
magnitude as the Delta outflow, and the overall estimate may be less accurate. For this
reason, there is a need to measure the outflows as directly and accurately as possible.
4.2.2.2 DEFICIENCIES IN EXISTING FLOW MONITORING DATA
Net Delta outflow is considered extremely challenging to measure. This is based on the
following current constraints:
• Existing installed flow monitoring stations
• Existing Acoustic Velocity Meter/Acoustic Doppler Current Profiler
(AVM/ADCP) technologies, methods and accuracies.
• Difficulty in determining net daily outflow from measured bi-directional velocity
profiles resulting from tidal flow and gravity driven flow.
• Availability of resources
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All of the methods currently used to measure flow in open channels in the Delta are based
on an Index Velocity Method (Levesque and Oberg 2012). Where an index velocity of a
portion of the total flow is measured (with AVM or ADCP) and that index velocity is
related to mean channel velocity through an index equation. The index equation is
developed by measuring the total channel flow with a moving boat ADCP while also
measuring the index velocity with the fixed instrument. The moving boat ADCP method
has errors of its own, and index ratings vary with flow and stage (water elevation).
In short, when attempting to measure a very small net daily outflow (NDO) (<10,000cfs)
by using a combination of flow meters at multiple locations, the combined
instrument/calibration errors of the flow measurements and the errors in calculating net
outflow from the total measured flow over a tidal cycle exceed the accuracy required.
4.2.2.3Possible Solutions to Improve Flow Monitoring accuracy
Measuring these net daily outflow under low-flow conditions will require more than adding
measurement locations or better index velocity meters at existing locations. It will take a
concerted effort and perhaps new technology and research to develop a measurement
system with sufficient accuracy to measure the desired flows, if it is possible at all.
One possibility might be a "large transect" approach where multiple meters at one location
(Chipps Island) could be used to fully characterize the velocities across the entire cross-
section and the index calibration for each small portion of the flow could be accurate
enough to characterize the low outflow periods. The feasibility of AVM flow measurement
at Chipps Island has previously been studied (Hoffard 1980), but no recent publications
were found that address the possibility of measuring Chipps Island channel flow with
currently available measurement technology.
While the AVM instruments installed in the Delta in the 1980s have now become difficult
to service and antiquated, their utility and proven technology could be used as a stepping
stone to a newer acoustic measurement system which might take advantage of the
substantial improvement in transducers, electronics and digital signal processing
technologies in the past 30 years.
The older AVM transit-time acoustic technology has been largely supplanted by the newer
acoustic Doppler (ADCP) technology due to cost, availability and utility of using ADCP
in fixed, side-looking, up-looking and boat mounted configurations. ADCP technology is
now off-the shelf and has instruments from several manufacturers (Appendix B) which are
specialized in physical configuration, electronics and processing capabilities for
oceanographic, hydrologic and industrial applications.
However, there has not (apparently) been sufficient market and financial incentive for
manufacturers to develop systems for large (wide) rivers which provide a high level of
accuracy which is now desired for the Bay Delta. This is not to say that it is not possible in
future, given the economic value associated with this measurement.
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4.3 Summary
In general, salinity measurement at the bottom could help to define X2 more accurately, or
another similar metric that adequately represents the position and volume of the low
salinity zone. These measurements could be made with commercially available sensors
although they have not been routinely made at most locations in the estuary. Direct
measurement of flow with commercially available instrumentation, on the other hand, are
considered much more difficult at this time, and will need much greater development effort
than bottom salinity measurements.
In support of this discussion, we performed a review of commercially available
technologies, including performance specifications and costs, for salinity and related water
quality measurements and for flow measurement (Appendices A and B, respectively).
Discussion of conceptual installation considerations are represented in Appendix C. These
appendices are intended to serve as a resource for available instrumentation and
installation, as further definition on the spatial and temporal accuracy as well as monitoring
goals, is obtained.
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5 USGS Monitoring Proposal
Here we present three monitoring options of varying degrees of complexity and costs, see
Table 5-1. The options, developed by Jon Burau of the USGS, incorporate salinity,
turbidity and velocity measurements that fit within the existing monitoring framework. Of
relevance to this proposal are installation, operation, data processing, and maintenance
costs associated with each plan. In the first option, requiring the greatest investment,
measurements are made at the spatial scales needed to resolve the physical processes that
drive salinity intrusion and ETM (estuarine turbidity maximum) formation. This plan
would generate data to forecast and hind-cast the position and character of the salt field.
The budgets associated with these plans are given as a point of reference in Section 5.3.
The monitoring options presented employ existing technologies that involve point
measurements of water quality constituents in the vertical (e.g. near-surface and near-bed
measurements of conductivity, temperature and turbidity). We know that these constituents
vary considerably in the vertical in the brackish portions of the estuary at seasonal, spring-
neap and tidal timescales depending on the strength of vertical stratification.
Measurements of complete vertical profiles of these constituents would be ideal for
developing the relations that capture the physics rather than using the near-surface and
near-bed measurements suggested here, because with point measurements we have to
infer/estimate the position and strength of the stratification within the water column.
A prototype instrument has been developed that can make continuous measurements of
vertical salinity profiles from an instrument mounted on the seafloor (Szuts et al., 2015).
This type of instrument would provide the invaluable resolution in the vertical because it
is mounted on the seafloor and can be deployed in the center of the channel. This is an
advantage over equipment deployed in the water column (e.g., a near-surface sensor) which
is not located in the center of the channel due to likely collisions with ship traffic in the
area. Moreover, since the strength of the gravitational circulation scales with depth,
obtaining a profile in the shipping channel where the depths are greatest is critical in being
able to correctly capture, calculate and model the rate of salinity intrusion.
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5.1 Overview
USGS has developed three (3) options for increasing the accuracy of salinity, flow, and X2
estimates by deploying and maintaining a number of additional salinity/turbidity sensors
in the channels in Suisun Bay and the western Delta as is shown in Figure 5-1. All of these
options provide, to varying degrees, data that will also provide the temporal evolution of
the along-channel spatial structure of habitat features for estuarine pelagic organisms such
as salinity, temperature and turbidity fields, in unprecedented detail in the region that has
the greatest abundance of adult Delta smelt in the summer through winter period (Moyle
et al 2016).
These data will give us the ability to calibrate and validate numerical models in this region,
which are increasing in sophistication and predictive capability. Additionally, these data
could be used to reformulate and evaluate the efficacy of the X2-abundance relationships
computed at a variety of times scales (daily, weekly, fortnightly and monthly).
Lastly, these monitoring designs are a platform to connect biological, ecological, and
hydrodynamic data and models. Adding biological monitoring at these sites would produce
a data set that could be used to identify and better describe the connection between the
physical processes (of which X2 is a bulk metric) and the biology and ecology of the
estuary. Hydrodynamic and biological data collected at these sites can then be used to make
the first tangible steps toward integrating biological and ecological models with
hydrodynamic models.
5.2 Instrumentation and Deployment Details
Three monitoring options of varying degrees of usefulness and rigor are outlined below.
These plans represent the extremes in effort (and cost), or bookends, ranging from the most
complex to the simplest. Variants of these options are also possible.
5.2.1 Option 1- Monitor X2 and the ETM with Greater Precision and Capture
the Physics
Beginning with the most extensive plan, which will allow us monitor X2 and the estuarine
turbidity maximum (ETM) with greater precision and to capture the physics, 11 stations
are proposed (Figure 5-1). In addition to deploying new instruments to collect both near-
surface and near-bed salinities at these 11 new monitoring stations, four upward-looking
acoustic Doppler current profilers (V-ADCP) will be deployed at the locations with the red
icons in Figure 5-1, to evaluate the contribution of gravitational circulation to salinity
intrusion, vertical stratification and ETM formation in the western Delta (Schoellhamer
and Burau, 1998).
The V-ADCP's will be deployed seaward of X2 to measure gravitational circulation during
periods when salinity has intruded into the Delta as far as salinity standards at Emmaton
and Jersey point will allow, a condition that typically occurs from mid-summer to the onset
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of winter storms, November-January, in a typical year. Gravitational circulation
contributes to salinity intrusion, and, hence the water cost associated with maintaining
salinity standards in the Delta, and the formation of an ETM immediately downstream of
X2. The placement of the V-ADCP's can be adjusted (up or down-estuary) as data
collection starts and we refine the positioning of X2 and our understanding of gravitational
circulation.
All of the data will be telemetered in real-time and made available on CDEC and NWIS-
web.
The YSI sondes associated with all of these plans will be mounted on Channel Markers -
out in the channel - potentially avoiding bias associated with measurements made on the
channel edge where lateral variability in constituents can exit.
The ADCPs will be deployed toward center channel to maximize the depth and cabled to
the data-loggers and telemetry systems on the channel markers.
Option 1 involves monitoring the near-bed and near-surface conductivity, temperature and
turbidity at 11 stations, which, when combined with 4 ADCP results in a total of 70 15-
minute time series that would be collected annually.
5.2.2 Option 2 - Monitor X2 and the ETM with Greater Precision Only
Option 2 is built on a significantly smaller deployment footprint at 9 stations (Figure 5-2)
and measurements of near-bed conductivity, temperature and turbidity only (e.g. no surface
measurements will be made) and no ADCP's, resulting in 27- 15-minute time series
collected annually.
5.2.3 Option 3 - Monitor X2 with Greater Precision Only
Option 3 is built on the same footprint as in plan 2 with 9 stations (Figure 5-2) and
measurements of near-bed conductivity and temperature (e.g. no turbidity measurements
and no surface measurements will be made) and no ADCP's, resulting in 18 15-minnute
time series collected annually.
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5.3 Cost Estimates Developed by USGS
Table 5-1
Cost Estimates of Three Monitoring Advancement Plans/Options
ft, w pr
X2 Monitoring Budgets
(1)
(2)
0)
rev: 1-31-17 (JRB;
Plan ->
Monitor X2 and ETM
with prreoter precision
and capture physics
Monitor X2 and £TM Monitor X2 with
with greater precision greater precision
Stations
11
9
9
Sensors per station
2
1
1
CT Sondes
22 9 9
Number of
Turbidity Probes
22
9
0
ADCP's
4
0
0
Time series
70
27
18
Unit costs
CT Sonde
Turbidity Probe
$13,000
$2,070
ADCP
$34,500
Instrument Shelter and ancillary equipmei
$9,540
OSM (CT) - Data Program
$13,000
O&M (CT — Existing Station) - Data Progra
$9,000
O&M (Turbidity) - Data Program
O&M (ADCP) Data Program
$8,400
$9,000
Equipment
$574,480
$221,490
$202,860
Installation labor
Backup sondes (tor tul! replacement during tiel
TOTAL INSTALLATION COSTS
$27,500
$180,840
$782,820
$22,000
$75,350
$318,840
$22,000
$65,000
$289,860
CT (O&M based on data program)
$143,000
$117,000
$117,000
O&M Costs
)&M existing station based on data prog
$99,000
$81,000
$81,000
ssed on Data PrograTurtoidity (O&M based on data program)
ADCP (O&M)
$184,800
$36,000
$75,600
$0
$0
$0
ANNUAL O&M COSTS (Data Program}
$462, BOG
$273,600
$198,000
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» jh,-h k v V.« i-fi «¦-« jr. i- •"
Figure 5-1 USGS Locations of Proposed Temperature, Salinity and Turbidity Monitoring
Equipment. All of the stations proposed are new (circle icons), except at MAL(s), RIO
and JPT (square icons), which are long-term monitoring stations run by the DWR-
RTM.
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Figure 5-2 USGS Locations of Proposed Temperature, Salinity and Turbidity Monitoring
Equipment. All of the stations proposed are new (circle icons), except at MAL(s), RIO
and JPT (square icons), which are long-term monitoring stations run by the DWR-
RTM.
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6 Report Summary and Considerations for
Monitoring System Improvement
The USGS approach presented in Chapter 6 is one possibility, and while it will
considerably improve the understanding of the physical system, this is also the time to
address broader concerns related to X2 position accuracy targets and other goals related to
the scientific need for the characterization of the low salinity zone. For example, the basic
concept of X2 was developed as a monthly index, although new research shows the
importance of changes at much smaller time scales (Reed et al., 2014). A plan for
monitoring should ideally address, as far as possible, the requirements of monitoring
(temporally and spatially) given the current understanding of estuarine biology.
Based on our understanding of the current systems in place, and work with similar systems
in other locations, we provide some general recommendations that could be considered.
6.1 Challenges in measuring near-bottom salinity
• Most of the USGS, DWRIMP-EMP water quality measurement sites are located
on fixed structures, piers, docks, etc. In many cases these platforms probably
don't extend over the deepest parts of the channel and thus may not provide
access to a salinity measurement location with appropriate depth.
• One of the biggest logistical issues in installing real-time near-bottom salinity
measurement instrumentation is the requirement for and vulnerability of the
instrument power and communications cable. Internally powered data logging
instruments overcome the cable limitation but lack the real-time reporting ability
(with a few possible exceptions presented in Appendix C).
• Most near-bottom salinity measurement solutions will be constrained by a)
access to and platform installation at an appropriate location for near-bottom
measurement and b) maintaining power and communications to the instrument.
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• High-velocity currents make it difficult to maintain a floating mooring and
instrument power/communications cabling from the surface to bottom.
• Vessel navigation requirements or channel size may not allow a platform in the
deepest part of the channel or the platform would be a navigation hazard.
• Reversing tidal currents and deep water prohibit dual or multipoint mooring,
which is necessary to eliminate instrument cable entanglement.
• Excessive sedimentation, bed morphology changes, etc. may affect the long-term
operation of the system.
• Other concerns that need to be kept in mind include: Excessive floating debris
that would interfere with instrumentation or platform; vandalism; biofouling,
maintenance and data degradation; and instrument Power/ communication cable
vulnerability.
6.2 Station Location Options
While the fixed (pile) navigation aids proposed by USGS are convenient locations for
installing the monitoring equipment, limiting the installation to these structures does not
allow monitoring at some desirable center-channel locations. As an example, there are no
US Coast Guard fixed navigation structures for a distance of approximately 6 km between
the east end of Middle Ground channel (km -71) and the mark North of New York Slough
(km -77). Within this reach the monitoring stations are placed near the shoreline at Mallard
Island.
Consideration of buoy mounted systems, perhaps with integrated mid-channel ADCP
might provide benefits for both salinity and flow monitoring over some of the selected pile
locations or the addition of another fixed shoreline station (MAL) on the North side of the
channel.
6.3 TECHNOLOGY AND METHODS TO CONSIDER
Possible solutions for near-bottom salinity measurement include:
• Installation of equipment on stationary pilings located in deep water with fixed-
cable top and near-bottom CTD sensors (although Aid-TO-Navigation (ATON)
pilings, day-marks and other structures, are typically located outside of the
channel).
• Floating multi-point mooring with fixed-cable top and near-bottom CTD sensors.
• Floating single or multi-point mooring with an automated mechanical vertical
profiling system and a single CTD sensor. This would provide even more
detailed salinity data and help to define the X2 location vertically in the water
column.
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• Floating single or multi-point mooring with an internally-powered near-bottom
CTD sensor and a wireless inductive mooring cable modem for near real-time
communications to the surface.
• Floating single or multi-point mooring with a pumped flow of water from the
near-bottom to a flow-through CT sensor at the surface.
• Deep-water bottom-mounted platform with single CTD sensor and power-
communications cables run across the bottom to shore.
• Near-bottom water intake pipe with a pumped flow of water to a flow-through
CT sensor on a mooring or fixed structure.
6.4 Changes to Data Analysis Methods
As new data are envisioned to be collected, potential analysis using these data can be
discussed. These include updates to the biology-low salinity zone relationships and updates
to the flow-salinity relationships, both using a range of tools from data driven statistical
approaches to three-dimensional models. Regardless of methods discussed at this point in
time, it is also worthwhile to address how these data will be used to translate to past
observations of surface salinity, which capture a long history of estuarine response to major
upstream changes in land use, water withdrawals, and reservoir construction, and also to
past sea level rise over the 20th century.
6.5 Summary
The review of information presented above, suggests that basic improvements to the
monitoring system could be put in place at a cost of ~ $1M in capital costs and $200,000/yr
in annual operations and maintenance. This report does not recommend a particular
implementation, but these costs are a reasonable starting point for planning purposes.
These improvements could greatly improve precision of compliance methods with existing
Delta outflow standard, support modifications to new Delta outflow standard, improve
modeling capability and accuracy for future predictions and past evaluations, and make
real progress in connecting hydrodynamic and biological measurements, integrating
biological and hydrodynamic modeling, and advancing our knowledge of estuarine
mechanisms that influence fish population trends. The specific needs for the monitoring
network and whether or not the improvements can be optimized for their potential outputs
was beyond the scope of the present document and needs to be based on a broader
discussion among the science experts, regulators, and the regulated community.
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7 References
This list includes references cited in Appendices A, B, and C.
Arthur, J. F., and Ball, M. D., 1978. Entrapment of suspended materials in the San
Francisco Bay-Delta estuary. U.S. Bureau of Reclamation, Sacramento, CA, 106p
ACT, 2007a. Alliance for Coastal Technologies; State Of Technology for In-Situ Measures
of Salinity Using Conductivity-Temperature Sensors, Workshop proceedings, Savanah
Georgia, December 3-5.
ACT, 2007b. Alliance for Coastal Technology, Customer Needs and Use Assessment
Summary; Use of satisfaction with, and requirements for In-situ salinity sensors.
ACT, 2008, Alliance for Coastal Technologies; Protocols for Verifying the Performance
of In-Situ Salinity Sensors, ACT_PV08-01 March 2008
Barrick, D., Teague, C., Lilleboe, P., Cheng, R., and Gartner, J. C. 2003. Profiling River
Surface Velocities and Volume Flow Estimation with Bistatic UHF Riversonde Radar,
Proceedings of the IEEE/OES Seventh Working Conference on Current Measurement
Technology. Pages: 55 - 59, DOI: 10.1109/CCM.2003.1194283
Buchanan, P. A., and Ruhl, C.A. 2001. Summary of Suspended-Sediment Concentration
Data, San Francisco Bay, California, Water Year 1999: U.S. Geological Survey Open File
Report 01-100, 56 p. URL http://water.usgs.gov/pubs/of/ofr01-100/.
Buchanan, P.A., Downing-Kunz, M.A., Schoellhamer, D.H., Shellenbarger, G.G., and
Weidich, K.W. 2014. Continuous Water-Quality and Suspended-Sediment Transport
Monitoring in the San Francisco Bay, California: U.S. Geological Survey Fact Sheet
2014-3090, 4 p., http://dx.doi.org/10.3133/fs20143090.
Buchanan, P. 2014 Personal communication with Paul Buchanan, USGS about USGS
equipment and methods for real-time water quality monitoring in San Francisco Bay,
December 12.
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Burau, J. R., Gartner, J. W., and Stacey, M. T., 1998. Results from the Hydrodynamic
Element of the 1994 Entrapment Zone Study in Suisun Bay, In Kimmerer, W. Ed., Report
Of The 1994 Entrapment Zone Study. Technical Report 56, Interagency Ecological
Program for the San Francisco Bay/Delta Estuary. 55p
Burau, J.R., Monismith, S.G., Stacey, M.T., Oltmann, R.N., Lacy, J.R., Schoellhamer,
D.H., 1999, Recent Research on the Hydrodynamics of the Sacramento-San Joaquin River
Delta and North San Francisco Bay. Interagency Ecological Program Newsletter, v. 11,
no. 2, p. 45-55.
Clifford, S. F. and Farmer, D.M. 1983. Ocean Flow Measurements using Acoustic
Scintillation, J. Acoust. Soc. Amer., vol.74 (6), pp. 1826-1832.
Department of Public Works, Division of Water Resources. 1931. Bulletin 27 Variation
and Control of Salinity in the Sacramento-San Joaquin Delta and Upper San Francisco
Bay.
Department of Water Resources (DWR). 2016. On Estimating Net Delta outflow (NDO).
March.
Di Iorio, D., and Barton, A. 2003. Path-Averaged Ocean Measurements in the Deep,
Stratified Tidal Channel of Hood Canal Using Acoustical Scintillation, J. Geophys. Res.,
108(C10), 3312, doi: 10.1029/2003JC001796.
Farmer, D. M. and Clifford, S. F., and Verrall, J.A. 1987. Scintillation Structure of a
Turbulent Tidal Flow, J. Geophys. Res., vol. 92 (C5), pp. 5396-5382.
Farmer, D. M. and Clifford, S. F. 1986. Space-time Acoustic Scintillation Analysis: A New
Technique for Probing Ocean Flows, IEEE J. Ocean. Eng., vol.OE-11(1).
Feyrer, F., Newman, K., Nobriga, M., and Sommer, T. 2011. Modeling the Effects of
Future Outflow on The Abiotic Habitat of an Imperiled Estuarine Fish. Estuaries and
Coasts, 34(1), 120-128.
Feyrer, F., Nobriga, M. L., & Sommer, T. R. 2007. Multidecadal Trends for Three
Declining Fish Species: Habitat Patterns And Mechanisms in the San Francisco Estuary,
California, USA. Canadian Journal of Fisheries and Aquatic Sciences, 64(4), 723-734.
Fofonoff, N.P., Millard, R.C., 1983. -Algorithms for computation of fundamental
properties of seawater; UNESCO technical Papers in Marine Science 44.
Gross, E. S., Koseff, J. R., & Monismith, S. G. 1999. Three-dimensional Salinity
Simulations of South San Francisco Bay. Journal of Hydraulic Engineering, 125(11), 1199-
1209.
Advancement of Salinity and Flow Monitoring February 2017
7-2
-------
Tetra Tech, Inc.
San Francisco Bay Delta Action Plan Implementation Support
Gross, E. S., N. J. Nidzieko, M.L. MacWilliams, and M.T. Stacey. 2007. Parameterization
of Estuarine Mixing Processes in the San Francisco Estuary based on Analysis of Three-
Dimensional Hydrodynamic Simulations. Journal of Estuarine and Coastal Modeling,
ASCE, pp. 322-338.
Gross, E. S., MacWilliams, M. L., & Kimmerer, W. J. 2010. Three-Dimensional Modeling
of Tidal Hydrodynamics in the San Francisco Estuary. San Francisco Estuary and
Watershed Science, 7(2).
Hoffard, S. H. 1980. Feasibility of Using an Acoustic Velocity Meter to Measure Flow in
the Chipps Island Channel, Suisun Bay, California USGS Open-File Report 80-697 (not
available electronically).
Hutton, P. H., J. S. Rath, L. Chen, M. J. Ungs, and S. B. Roy. 2015. Nine Decades of
Salinity Observations in the San Francisco Bay and Delta: Modeling and Trend
Evaluations. ASCE Journal of Water Resources Planning and Management
10.1061/(ASCE)WR. 1943-5452.0000617, 04015069.
Jabusch T. and Gilbreath, A. 2009. Aquatic Science Center, Summary of Current Water
Quality Monitoring Programs in the Delta. Prepared for Central Valley Regional Water
Quality Control Board, State Water Resources Control Board November.
http://www.swrcb.ca.gov/centralvalley/water_issues/delta_water_quality/comprehensive_
monitoring_program/2009nov25_deltamon_draft_final.pdf.
Janzen C., Larson N., Moore, M. 2008. WQM: New Instrumentation for Coastal
Monitoring- Extending Deployment s and Reducing Cost by Preserving Long-Term
Accuracy. Sea Technology Magazine,
http://sbe.seabird.com/technical_references/WQM-SeaTechnologyFeb08WithSTlogo.pdf
Jassby, A.D., W.J. Kimmerer, S.G. Monismith, C.Armor, J.E. Cloern, T.M. Powell, J.R.
Schubel and T.J. Vendlinski. 1995. Isohaline Position as a Habitat Indicator for Estuarine
Populations. Ecological Applications 5: 272-289.
Kimmerer, W. J., Gross, E. S., and MacWilliams, M. L. 2009. Is the Response of Estuarine
Nekton to Freshwater Flow in the San Francisco Estuary Explained by Variation in
Habitat Volume? Estuaries and Coasts, 32(2), 375-389.
Laenen, A. 1985. Acoustic velocity meter systems: U.S. Geological Survey Techniques of
Water-Resources Investigations, Book 3, chap.A17, 38 p.
Lemon D. D., Clifford, S.F., Farmer, D. M. Parker, B.B. 1986. Scintillation current
measurements, a new approach to real-time current measurements in channels and
harbours, Applications of Real-time Oceanographic Circulation Modelling Symposium
Proceedings.
Advancement of Salinity and Flow Monitoring February 2017
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Lemon, D. D. and Farmer, D.M. 1990. "Experience with a multi-depth scintillation
flowmeter in the Fraser estuary," Proc. of the IEEE Fourth Working Conference on
Current Measurement, Clinton, MD, pp. 290-298.
Levesque, V.A., and Oberg, K.A. 2012. Computing discharge using the index velocity
method: U.S. Geological Survey Techniques and Methods 3-A23, 148 p. (Also available at
http: //pubs .usgs .gov/tm/3a23/.).
MacWilliams, M. L., Bever, A. J., Gross, E. S., Ketefian, G. S., Kimmerer, W. J., and
Center, R. T. 2015. Three-Dimensional Modeling of Hydrodynamics and Salinity in the
San Francisco Estuary: An Evaluation of Model Accuracy, X2, and the Low-Salinity Zone.
San Francisco Estuary and Watershed Science, 13(1).
Mierzwa, M. 2002. Chapter 4: CALSIM versus DSM2 ANN and G-model Comparisons.
Methodology for flow and salinity estimates in the Sacramento-San Joaquin Delta and
Suisun Marsh. 23rd Annual Progress Report. June.
Monismith, S. G., Kimmerer, W., Burau, J. R., and Stacey, M. T. 2002. Structure and
Flow-Induced Variability of the Subtidal Salinity Field in Northern San Francisco Bay.
Journal of Physical Oceanography, 32(11), 3003-3019.
Moyle, P.B., Brown, L.R., Durand, J.R., Hobbs, J.A. 2016. Delta Smelt: Life History and
Decline of a Once-Abundant Species in the San Francisco Estuary. San Francisco and
Estuary Watershed Science, 14(2) July 2016.
Oltmann R.N. , Simpson M.R. (undated) Measurement of Tidal Flows in the Sacramento-
San Joaquin Delta, California- U. S. Geological Survey, Sacramento, California-mini
Poster, on the Internet at
http://sfbay.wr.usgs.gov/watershed/tidal_flow/images/miniposter.pdf.
Radtke, D.B., Davis, J.V., and Wilde, F.D., eds. 2005. Specific Electrical Conductance
(version 1.2): U.S. Geological Survey Techniques of Water-Resources Investigations, book
9, chap. A6, section 6.3, 22 p.; http://pubs.water.usgs.gov/twri9A6/.
RBR. 2010. Advantages in Performance of the RBR Conductivity Channel With
Delrintm/Ceramic Inductive Cell. I. Shkvorets and F. Johnson, OCEANS Conference 2010.
Reed D. et al. 2014. Panel Summary Report on the State Water Resources Control Board's
Workshop on Delta outflows and Related Stressors, on the Internet at:
http://deltacouncil.ca.gov/sites/default/files/documents/files/Delta-Outflows-Report-
Final-2014-05-05.pdf.,.
Roy, S.B., Rath, J., Chen, L., Ungs, M.J., and Guerrero, M. 2014. Salinity Trends in Suisun
Bay and the Western Delta (October 1921 - September 2012), Prepared for the San Luis
and Delta Mendota Water Authority and State Water Contractors, January.
Advancement of Salinity and Flow Monitoring February 2017
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Ruhl, C. A., and Simpson, M. 2005. Computation of Discharge Using the Index-Velocity
Method in Tidally Affected Areas U.S. Geological Survey Scientific Investigations Report
2005-5004.
Ruhl, C. A. and DeRose J. B. 2004. Investigation of Hydroacoustic Flow-Monitoring
Alternatives at the Sacramento River at Freeport, California: Results of the 2002-2004
pilot study. Scientific Investigation Report, USGS, 2004-5172.
Schoellhamer, D. H., Buchanan, P. A., and Ganju, N. K. 2002. Ten Years of Continuous
Suspended-Sediment Concentration Monitoring In San Francisco Bay And Delta;
Turbidity and Other Sediment Surrogates Workshop, April 30 - May 2, 2002, Reno, NV.
Schubel, J.R., et al. 1993, Managing Freshwater Discharge to the San Francisco
Bay/Sacramento-San Joaquin Delta Estuary — The Scientific Basis for an Estuarine
Standard: San Francisco Estuary Project, U.S. Environmental Protection Agency, San
Francisco, CA, 109 p. (Accessible May 1, 2014 at:
http://www2.epa.gov/sites/production/files/documents/sfep_1993_managing_fw_dischar
ge_sf_bay_delta_estuary_0.pdf)
Stacey, M.T., Brennan, M.L., Burau, J.R. and Monismith, S.G. 2010. The Tidally Averaged
Momentum Balance in a Partially and Periodically Stratified Estuary, J. Phys. Oceanogr.,
v. 40, 2418-2434.
State Water Resources Control Board. 1999 Water Right Decision 1641, on the Internet at:
http://www.swrcb.ca.gov/waterrights/board decisions/adopted orders/decisions
/d!600 d 1649/wrd 1641 .pdf.
State Water Resources Control Board. 2006. Water Quality Control Plan for the San
Francisco Bay/Sacramento-San Joaquin Delta Estuary, on the Internet at: Division of
Water Rights. htttp://www.waterboards.ca.gov/waterrights/water_issues/
programs/bay_delta/wq_control_plans/2006wqcp/index.shtml
Simpson, M. and Bland, R. 2000. Methods for Accurate Estimation of Net Discharge in a
Tidal Channel IEEE Journal of Oceanic Engineering, Volume: 25, Issue: 4, Pages: 437 -
445, DOI: 10.1109/48.895351.
Szuts B.Z., A.A. Ganse, and T.B. Sanford, 2015, Continuous Monitoring of Salinity
Profiles from a Seafloor Instrument, Poster, 23rd Coastal and Estuarine Research Federation
(CERF) Biennial Conference, Portland Oregon, 8-12, November 2015.
Teague, C.C., Barrick, D., Lilleboe, P.M., Cheng, R.T., Stumpner, P., Burau, J.R. 2008.
"Dual-River Sonde Measurements of Two-Dimensional River Flow Patterns," in Current
Measurement Technology, 2008. CMTC 2008. IEEE/OES 9th Working Conference
pp.258-263, doi: 10.1109/CCM.2008.4480877.
Advancement of Salinity and Flow Monitoring February 2017
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San Francisco Bay Delta Action Plan Implementation Support
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UNESCO. 1988. The acquisition, calibration and analysis of CTD data, UNESCO
Technical papers in marine science, No. 54, 94pp.
US Bureau of Reclamation. 2013. Laboratory Evaluation of Open Channel Area-Velocity
Flow Meters. Hydraulic Laboratory Report HL-2012-03.
USGS Nov 2013 Fact Sheet 2013-3-37
(http://pubs.usgs.gov/fs/2013/3037/pdf/fs2013-3037.pdfUSGS Science at Work in the San
Francisco Bay and Sacramento-San Joaquin Delta Estuary).
Wagner, R.J., Boulger, R.W., Jr., Oblinger, C.J., and Smith, B.A. 2006. Guidelines and
Standard Procedures for Continuous Water-Quality Monitors—Station Operation, Record
Computation, and Data Reporting: U.S. Geological Survey Techniques and Methods 1-
D3, 51 p. + 8 attachments; accessed April 10, 2006, at http://pubs.water.usgs.gov/tmld3.
Woody, C., E. Shih, J. Miller, T. Royer, L.P. Atkinson, R.S. Moody, 2000.Measurements
of Salinity in the Coastal Ocean: A Review of Requirements and Technologies. Marine
Technology Society Journal, 34(2), 26-33.
XYLEM, Inc. 2015 - 6-Series Discontinuation Schedule YSI plan for 6-series phase out
and future support.
YSI. 2010. Using a Copper-Alloy Based System for Effective Biofouling Deterrence, YSI
Incorporated.
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APPENDIX A:
Salinity / Conductivity Instrumentation
Equipment Overview, Comparison and
Manufacturers' Specifications
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A. Conductivity/Salinity
Instrumentation
A.1 Overview
Water conductivity and temperature (CT) are measured directly using a submerged or flow-
through sensor and conductivity is typically reported as specific conductance standardized
to a temperature of 25°C (77°F). Salinity is typically calculated from the measured
conductivity and temperature, depending upon the specific sensor type, the salinity
standard in use and the units being used to report the data (Fofonoff, N.P.; Millard, R.C.,
1983).
Conductivity probes are available from a wide range of manufacturers of oceanographic
and engineering equipment and are generally referred to as CT sensors, or CTD when depth
measurement is integrated. The conductivity probes are compact, as small as 4 inches long
by 1 inch diameter. Measurements can be recorded over a wide range of user-defined
intervals, from seconds to hours or days. The collected data are stored either internally or
externally via a cable to a data logger. Instrument vendors usually provide dedicated data
loggers and frequently can provide integrated telemetry systems, as well.
A.2 Resources for Sensor Evaluation and Performance
Verification
The Alliance for Coastal Technologies (ACT) is a partnership of research institutions,
resource managers, and private sector companies dedicated to fostering the development
and adoption of effective and reliable sensors and platforms for use in coastal, freshwater
and ocean environments. Because of their unique affiliation and specific involvement with
the evaluation of conductivity/salinity sensors, ACT is a key resource for identifying State-
of-the-Art sensor technology. ACT serves as an unbiased, third party test bed for evaluating
sensors and provides technology verifications of specific manufacturer's instruments.
ACT conducts two levels of Technology Evaluations: Verifications and Demonstrations.
Technology Verifications focus on classes of commercially available instruments to
provide confirmation that each technology meets the manufacturer's performance
specifications or claims and/or provides verified data on those operational parameters that
stakeholders require to make a use decision. Verifications are a 25-step process, which
includes community consensus on test protocols, laboratory and field-testing, and QA/QC
based on Environmental Protection Agency (EPA) and International Organization for
Standardization (ISO) guidelines. Field tests are carried out at no fewer than four but
typically all six ACT partner sites. Technology Demonstrations involve fewer steps and
focus on highlighting the capabilities and potential of pre-commercial or emerging early-
stage technologies, building user awareness, and facilitating technology maturation and
transition into operational observing. Working closely with developers, Demonstration
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field tests may be conducted at only two or three Partner sites, depending on stakeholder
priority needs.
ACT Technology Evaluations also are open and transparent, free of charge for all
applicants with appropriate instrumentation, and all results are released to the public in
final reports. However, ACT and its Partner Institutions do not certify or guarantee
performance of technologies, nor does ACT rank or directly compare the individual
instruments tested.
A.3 Current State of Salinity Monitoring Technology
When evaluating conductivity/salinity instrumentation, several things should be
considered, including:
• The current state-of-the-art in electrical conductivity measurement for water quality
monitoring has not changed significantly since 2000 (ACT 2007a).
• Due to the capital, installation and maintenance costs of water quality measurements,
conductivity and temperature are rarely the only parameters measured at a monitoring station.
(ACT 2007b)
• The selection and purchase of water quality monitoring instrumentation is often driven by the
need for simultaneous measurement of parameters other than conductivity so, rather than
recommending a specific manufacturer's model of instrument, specifications for required
salinity accuracy should be driven by instrument conductivity specifications (i.e. accuracy,
range) while allowing the user to select the most appropriate combined-sensor package if
required. (ACT 2007b)
• Current development efforts related to conductivity measurement have been focused on
methods to limit sensor bio-fouling, which helps to maintain measurement accuracy, ensure
long term data stability, increase deployment duration and decrease maintenance costs. Some
examples of these anti-biofouling methods are outlined in Table A-l.
• The Alliance for Coastal Technologies estimates that maintenance costs due to biofouling
consume 50% of operational budgets. Over the years, methods for combating biofouling on
submerged sensors have evolved from the use of toxic chemicals and pumps to more
mechanical systems that use wipers or shutters to combination systems that use mechanical
systems and technologies such as ultrasonic or chlorine generation systems. (YSI 2010)
• "Data from deployments indicated that anti-fouling hardware effectively provided viable data
for deployments longer than 40 days. Without anti-fouling hardware, sensors were affected
by fouling in as few as nine days. By using anti-fouling components, the monitoring program
in St. Petersburg Harbor decreased its maintenance visits by 66% and saved $10,000. Overall,
anti-fouling components for water quality instruments very effectively extend deployment
times and collect high quality data for water managers." (YSI 2010)
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Table A-1
New Developments in Anti-biofouling Technology
New Technology
Description
AML-UV'Xchange™
UV-Xchange is a subsea module that prevents biofouling during long-term,
in-situ deployments. UV-Xchange inhibits marine growth by bathing critical
surfaces in ultraviolet (UV) light. Comparative studies show UV-Xchange
to be as effective as leading chemical protection methodologies, such as
bis(tributylin)oxide (TBT), at eliminating drift due to biofouling in CTDs and
multi-parameter instruments.
YSI-6-Series
Copper Sensor and Sensor
Guard Components
YSI Environmental has developed a copper-alloy based system to
significantly slow the rate of biological fouling on water quality
instruments and extend long-term instrument deployments. These "anti-
fouling kits" are an affordable solution to biofouling and thereby decrease
the number of site visits and maintenance needed at remote sites (YSI,
2010).
YSI-EXO series new
independent Antifouling wiper
and U-shape conductivity
probe.
The newly designed EX02 Central Wiper occupies the central port on an
EX02 sonde rather than being separate wipers incorporated into
individual sensors as in the 6-series. To keep it from interfering with data,
an EX02 sonde can be equipped with this anti-fouling wiper to prolong
deployments and improve data accuracy. Note: A biennial (every two
years) wiper shaft o-ring replacement is necessary to maintain optimum
performance of the EX02 central wiper.
RBR Inductive Cell
Technology
Instruments that use inductive cell technology are not as susceptible to
biofouling due to the configuration of the sensor. Whereas conductivity
meters have electrodes in direct contact with the water and are subject to
fouling, the inductive meter requires only submersion of the sealed
electrical coil, which measures the inductance of the fluid without
electrical contact. (RBR, 2010).
Seabird-Coastal - WQM
Technology
An instrument the water quality monitor (WQM), integrates high-accuracy
sensors to measure pressure, temperature, salinity, dissolved oxygen,
chlorophyll fluorescence and turbidity. The WQM design includes several
synergistic anti-foulant strategies such as unique plumbing that protects
the sensors from continuous exposure, passive diffusion of anti-foulant,
and a copper guard installed over the sensors (Janzen, Larson and
Moore, 2008).
MicroCAT/HydroCAT
antifoulant-protected flow
path
The Sea-Bird Coastal MicroCAT/HydroCAT measure and record
conductivity, temperature and optical dissolved oxygen ensuring long
term data stability. The HydroCAT has unique bio-fouling protection
method using an integral pump, and unique internal flow path, and EPA-
approved anti-foulant devices installed in the flow path. This configuration
minimizes biological contact and flow across the sensor between
samples and provides stable measurements throughout a deployment.
A.4 Conductivity/Salinity Sensors for Consideration
Existing and newer conductivity sensors to be considered for the Bay Delta Action Plan
are presented in Table A-.
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Table A-2
Conductivity/Salinity Sensors for Consideration
Instrument
Description
Pros
Cons
Capital Cost
YSI 6-Series
These water quality sondes are ubiquitous
in the measurement community. Over the
past two decades 28 varieties of 6-Series
instruments have been manufactured to
meet the needs of customers across the
globe. These sondes are used extensively
by EPA, USGS, and NOAA throughout the
US.
Very widely used/accepted sensor
systems. Copper-based antifoulant
probes. High-quality at reasonable
cost.
Older electronics nearing
obsolescence. Phase out
2018-2021.
Self-cleaning sensors have
proven to reduce data loss only
in relatively fresh water
because they are ineffective
when fouling is excessive and
they are prone to leak and
malfunction in saltier
water.(Buchanan and Ruhl
2001)
$3800-$7400+
depending upon
sensors
installed.
YSI EXO Series
The EX02 water quality sonde are new YSI
multi-parameter instruments that can
accommodate up to six user-replaceable
sensors, a central wiper to keep sensors
clean of biofouling, and an integral
pressure transducer for depth. The EXOI
can accommodate fewer sensors.
YSI EXO Conductivity Sensor (New Fall
2015)
Newer electronics, titanium sensors
and data storage technology. Smart
ports on the sonde accept any EXO
water quality sensor. Newer
independent wiper mechanism
eliminates leaks from having wiper
integrated into individual sensors.
Currently fewer copper-based
antifouling sensors with this
compared with 6-Series
EX02 sonde
with pressure:
$6980
CT sensors:
$820
Turb: $1800
Wiper: $1010
Cable: $ 500
Total: -$11,110
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Table A-2
Conductivity/Salinity Sensors for Consideration
Instrument
Description
Pros
Cons
Capital Cost
SBE-
37SIP/37SMP
MicroCAT CTD family, which make
measurements at user-programmable
intervals. All MicroCATs:
•Measure Conductivity and Temperature.
•Can include an optional strain-gauge
Pressure sensor.
•Can include an integrated pump for
improved bio-fouling protection and
improved conductivity and oxygen sensor
response.
•Have 8 Megabyte memory.
•Are available for depths to 350 meters
(plastic housing) or 7000 meters (titanium
housing).
Proven long-term stability and high-
accuracy. Specialized antifouling with
integral pump and flow path, high
accuracy, long term (30-90 days)
stability (<3% error) in biofouling
environments.
Capability to add SeapHOx and
Optical DO sensors. Capability to add
inductive-cable modem telemetry.
Do not incorporate a Turbidity
sensor at instrument level. Has
to be incorporated as an
external sensor via cable.
$8000 Ext
Power
$8500 Internal
Pwr
Sea-Bird
Coastal
HydroCAT
Conductivity, temperature, depth and
optical dissolved oxygen sensor designed
for long term deployments.
Specialized antifouling with integral
pump and flow path, high accuracy,
long term (30-90 days) stability (<3%
error) in biofouling environments
No other sensors can be
integrated directly to
instrument.
$9000
Sea-Bird
Wetlabs WQM
Designed specifically for long-term moored
operations in biologically rich water.
Sensors include fluorometer, conductivity,
temperature and depth. Includes active flow
control, passive flow prevention, light-
blocking, active biocide injection and
passive inhibitors to limit biofouling
Specialized antifouling with active
injection and copper optical shutters.
Has integrated fluorometer for
measuring fDOM
No other sensors can be
integrated directly to
instrument.
Slightly higher capital cost and
requirement to handle biocide
chemicals during servicing.
$14000
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Table A-2
Conductivity/Salinity Sensors for Consideration
Instrument
Description
Pros
Cons
Capital Cost
AML MetrecX
Metrec-X is an externally-powered,
multiparameter instrument that allows you
to change the instrument's sensor load, in
the field and on-demand.
Specialized UV-Xchange antifouling
with
•No toxic chemicals.
•No moving parts and hence greater
reliability compared to wipers.
•Protects complex and delicate
surfaces, for which wipers are
unsuitable.
•Adjustable LED sub-modules ensure
effective coverage of all critical
surfaces, regardless of geometry.
No internal battery
$11300
AML Plus X
Plus*X is a logger that allows you to
change the instrument's sensor load, in-
the-field and on-demand. With Plus*X, your
CTD can become an sound velocity
temperature profiler (SVTP); shallow
pressure sensors can be swapped for
deep; and temperature range can be
extended or tightened, as needed. One
single logger meets multiple deployment
requirements.
Specialized UV-Xchange antifouling
$14300
RBR Concerto
CTD Inductive
Sensor
Inductive meter for determination of
conductivity/salinity temperature. Toroidal
sensor design, encased in plastic is a non-
contact conductivity meter with good
antifouling capability.
Testing has shown biofouling has much
less effect on conductivity
measurements that direct-contact
conductivity probes.
No other sensors can be
integrated directly to
instrument.
$6,750 w/cable
APL-UW Sigma
Profiler
University of Washington Applied Physics
Lab's Experimental Water Column
Conductivity instrument.
Measures conductivity as a function of
depth and time in the water column.
Longer endurance and reliability than
mechanical CTD systems. Measures
conductivity of water column.
Not a commercial product, In
development.
N/A
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Table A-3
Instrument Sensor Specification Comparison
Instrument
Range
Resolution
Accuracy
Stability
Respons
e time
OR Time
constant
Maintena
nee
Interval
YSI 6-Series
Conductivity (6560)
Temperature(6560)
Depth (Medium)
Dissolved 02 (6150)
0 to 100 mS/cm
-5 to +50°C
0-61 m
0 to 50 mg/L
0.001 to 0.1
mS/cm
o.orc
0.001 m
0.01 mg/L
±0.5% of reading + 0.001 mS/cm
±0.15°C
± 0.003 m
0 to 20 mg/L: ± 0.1 mg/L or 1% of
reading, whichever is greater: 20 to
50 mg/L: ±15% of reading, relative
to calibration gases
?
?
1-5 weeks
YSI EXO Series
Conductivity (?#)
Temperature
Depth
Dissolved 02 (Optical)
Turbidity
0 to 200 mS/cm
-5 to 50°C0-0 to
100 m
to 50 mg/L
to 0.01 mS/cm
0.01 °C
0.01 m
0.01 mg/L
0 to 100: ±0.5% of reading or 0.001
mS/cm
-5 to 35°C: ±0.01 °C, 35 to 50°C:
±0.05°C
±0.04 m
0 to 20 mg/L: ±0.1 mg/L or 1% of
reading, w.i.g.; 20 to 50 mg/L: ±5%
of reading
?
T63<2
sec
T63<1
sec
T63<2
sec
T63<5
sec
1-5 weeks
SBE-37SIP/37SMP
Conductivity
Temperature
Depth
0 to 70 mS/cm
-5 to +45 °C
0 to 20 m
0.0001 mS/cm
0.0001 °C
0.002%
±0.0003 S/m
±0.002 °C l± 0.01oC (over 32°C)
± 0.1%
0.0003
S/m/month
0.0002 °C/month
0.05%
1-6
months
Sea-Bird Coastal
HydroCAT
Conductivity
Temperature
Depth
Dissolved 02 (Optical)
0- 70 mS/cm
-5 to 45°C
0- 20 m
120% of surface
saturation
0.0001 mS/cm
o.ooorc
0.002%
0.007 mg/L
± 0.003 mS/cm
± 0.002°C/± 0.01oC (over 32°C)
± 0.1%
± 0.1 mg/L or
± 2% whichever is greater
0.003
mS/cm/month
0.0002°C/month
0.05%
< 0.03 mg/L/
100,000 samples
?
1-3
months
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Table A-3
Instrument Sensor Specification Comparison
Instrument
Range
Resolution
Accuracy
Stability
Respons
e time
OR Time
constant
Maintena
nee
Interval
Sea-Bird Wetlabs
WQM
Conductivity
Temperature
Depth
Optical DO
Chlorophyll (Several)
Turbidity (Several)
CDOM
0- 90 mS/cm
-5 to 45°C
0-100 m
120% of surface
saturation
0- 250 |jg Chi
0- 250 |jg Chi
0- 375 ppb
0.0001 mS/cm
o.ooorc
0.002%
0.035% of
saturation
± 0.003 mS/cm
± 0.002°C/± 0.01 °C (over 32°C)
± 0.1%
± 2% of saturation
0.28 ppb
0.003 mS/cm
0.002°C/month
0.05%
.5% per 1000
hours
1-3
months
AML MetrecX
Conductivity (RA090)
Temperature (n545)
Depth (0050)
Turbidity (Several)
0-90 mS/cm
-5-45°C
0 to 50 m
1 to 3000 NTU
0.001 mS/cm
o.oorc
0.02%
0.01 to 0.1 NTU
0.01 mS/cm
0.005°C
0.05%
1 to 5%
25 ms
100 ms
10 ms
<0.7s
AML Plus X
Conductivity (RA090)
Temperature (n545)
Depth (0050)
Turbidity (Several)
0-90 mS/cm
-5-45°C
0 to 50 m
1 to 3000 NTU
0.001 mS/cm
o.oorc
0.02%
0.01 to 0.1 NTU
0.01 mS/cm
0.005°C
0.05%
1 to 5%
25 ms
100 ms
10 ms
<0.7s
RBR Concerto CTD
Inductive Sensor
Conductivity
Temperature
Depth
0-85mS/cm
-5°C to 35°C
0 to 50 m
~1 pS/cm
<0.00005°C
<0.001%
±0.003 mS/cm
±0.002°C
±0.05%
~1 pS/cm/month
~0.002°C/year
~0.1%/year
<100ms
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Table A-4
Instrument Physical Specification Comparison
Instrument
Housing Material
Depth Rating
Anti-Fouling
Acquisition Time
External Power
Memory Capacity
YSI 6-Series
Plastic
200 m
Copper Alloy
Accessories
12 V DC
YSI EXO Series
Plastic
250 m
Copper Alloy
Accessories
1,000,000 logged
readings
SBE-
37SIP/37SMP
Plastic
350 m
Expendable
devices
1.0-2.9 sec/sample
0.25 to 0.5 A at 8.5
to 24 VDC
530,000 samples
CTD
Sea-Bird Coastal
HydroCAT
Plastic
350 m
Anti-fouling
capability
2.3-3.2
sec/sample
0.25 A at 9 to 24
VDC
Sea-Bird Wetlabs
WQM
Plastic (Acetal
copolymer, ABS,
PVC, titanium,
copper)
200 m
Anti-fouling
capability, copper
alloy
1 Hz
350 mA Peak, 9 -
16 VDC
AML MetrecX
Hard anodized
Aluminum
6000 m
Ultraviolet LED
light
Scan up to 25 Hz
10 to 36 VDC
Gigabyte non-
volatile memory
AML Plus X
Hard anodized
Aluminum
5000-6000 m
Ultraviolet LED
light
Scan up to 25 Hz
10 to 36 VDC
Gigabyte non-
volatile memory
RBR Concerto
CTD Inductive
Sensor
Plastic
740 m
1s to 24 h
30M readings
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A.4.1 YSI 6-Series water quality sondes
During the early 1990's, YSI introduced what has become one of the most widely used
water quality instrument systems - the 6-Series environmental monitoring sondes. Over
the past two decades what started as a single sonde product evolved over 28 varieties of 6-
Series instaimentation to meet the needs of customers across the globe. These sondes are
used extensively by EPA, USGS, and NOAA throughout the US. The 6-Series will be
phased out over the next 3-5 years and will be replaced with the YSI-EXO series (Xylem
2015).
The most robust and newest of the 6-series sondes is the YSI 6920 V2 water quality logging
system which is ideal for economical long-term in situ monitoring and profiling. The sonde
comes in two versions:
• 6920 V2-1 has 1 optical port, 1 conductivity/temperature port, 1 Rapid Pulse Dissolved
Oxygen port, 1 pH/ORP port, and 3 ISE ports
• 6920 V2-2 has 2 optical ports, 1 conductivity/temperature port, 1 pH port, and 1 ISE port
Available optical sensors include:
• ROX optical dissolved oxygen
• Blue-green algae
• Chlorophyll
• Turbidity
• Rhodamine
A pressure sensor is an option on both versions.
Figure A-1
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Additional parameters include:
• Salinity
• Specific Conductance
• Depth or Shallow Vented Level
• Total dissolved solids (TDS)
• Open-channel Flow
• Nitrate-nitrogen, Ammonia/Ammonium-nitrogen, or Chloride (ISEs)
The manufacturer's specifications for this instrument are included in Appendix A.
A.4.2 YSI - EXO series water quality sonde
YSFs EXO sonde platform was launched in 2012. Much like the 6-Series platform, YSI
plans to grow and evolve the EXO meter series to meet the needs of specific applications.
The EX02 water quality sonde is a new YSI multi-parameter instrument that collects data
with six user-replaceable sensors, a central wiper to keep sensors clean of biofouling, and
an integral pressure transducer for depth. Each sensor port on the sonde accepts any EXO
water quality sensor and automatically recognizes it.
Newest Conductivity Sensor Option ( Fall 2015)
Sensor Options:
• Conductivity and Temperature
• Dissolved Oxygen (optical)
#
Figure A-2
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• fDOM (Fluorescent Dissolved Organic Matter, surrogate for CDOM)
• pH or pH i ORP
• Depth (integral)
• Total Algae (Dual-channel Chlorophyll and Blue-green Algae)
• Turbidity
Data Collection Options:
• Store onboard the sonde
• Transfer data to DCP
• Relay data to PC
• Relay data to EXO Handheld
The manufacturer's specifications for this instrument are included in Appendix A.
A.4.3 Seabird Electronics SBE-37 MicroCAT
Figure A-3. Seabird MicroCAT SBE-37
Sea-Bird manufactures a number of instruments within the MicroCAT CTD family, which make
measurements at user-programmable intervals. All MicroCATs:
• Measure Conductivity and Temperature.
• Can include an optional strain-gauge Pressure sensor.
• Can include an integrated pump (P in the model number designation) for improved bio-
fouling protection and improved conductivity and oxygen sensor response.
• Have 8 Megabyte memory.
• Are available for depths to 350 meters (plastic housing) or 7000 meters (titanium
housing).
Some MicroCATs also include Dissolved Oxygen:
• 1DO MicroCATs include a membrane-type Dissolved Oxygen sensor.
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• ODO MicroCATs include an Optical Dissolved Oxygen sensor.
The SBE 37-SMP-ODO MicroCAT can be integrated with a pH sensor to provide CTD + DO +
pH:
A.4.4 Sea-Bird Coastal HydroCAT
Figure A-4
The Sea-Bird Coastal HydroCAT with technology by Sea-Bird Electronics (SBE)
measures and records conductivity, temperature and optical dissolved oxygen ensuring
long term data stability. Depending on the application, the HydroCAT can collect high
quality data for several months up to a year. Excellent bio-fouling protection is provided
by US EPA-approved anti-foulant devices, integral pump, and unique internal flow path,
which minimizes flow between samples and provides stable measurements throughout a
deployment.
Conductivity and temperature sensors are based on field proven Sea-Bird Electronics
(SBE) CTD products. The aged and pressure- protected thermistor has a long history of
exceptional stability and accuracy. The oxygen sensor was designed by SBE to meet the
demand for a low maintenance and high accuracy sensor for use in applications such as
hypoxia monitoring. All HydroCAT sensors are built with careful choices of materials and
geometry combined with superior electronics and calibration methodology to optimize
field performance.
AAA.1 Applications
For continuous or real-time measurement of conductivity, temperature, depth and dissolved
oxygen in:
• Estuaries
• Lakes and reservoirs
• Rivers and streams
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A. 4.4.2 Performance Features and Benefits
• Robust - Excellent anti-fouling capability- EPA approved anti-foulant device and pumped
internal flow path for maximum biofouling protection
• Accurate- High initial accuracy and low drift rate
• Cost Effective- No in-field calibrations required, common deployment duration of three plus
month, reducing field costs
A.4.4.3 Additional Features
• Each instrument is factory calibrated in a temperature controlled bath that operates at 2-4
times the accuracy of the instrument.
The manufacturer's specifications for this instrument are included in Appendix A.
A.4.5 Sea-Bird Coastal WQM X
Figure A-5
The Sea-Bird Coastal WQM X with technology by WET Labs and Sea-Bird Electronics is
designed specifically for long-term moored operations in biologically rich water. The
WQM X combines WET Labs" state of the art fluorometers with cutting edge conductivity,
temperature, and depth technology from Sea-Bird Electronics to create a monitoring Sonde
with unprecedented long-term deployment capabilities.
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Ideally suited for unattended monitoring the WQM employs active flow control, passive
flow prevention, light-blocking, active biocide injection and passive inhibitors to combat
internal and external fouling.
The manufacturer's specifications for this instrument are included in Appendix A.
A.4.6 RBR XR-420/ XR-620 (Concerto) CTD loggers
http://www.rbr-global.com/products/ct-and-ctd-loggers
The RBRt/wo C.T and the KBRconcerto C.T.D are unique data loggers dedicated to the
determination of salinity. Salinity is calculated by measuring the conductivity and
temperature of the water. Equipped with a depth sensor, the RBR concerto C.T.D can also
derive density anomaly and speed of sound. The RBRt/wo C.T and the RBRcowcerto C.T.D
are available in configurations that support moored or profiling applications. Both loggers
meet World Ocean Circulation Experiment (WOCE) accuracy and resolution standards and
are NIST traceable.
Figure A-6
A. 4.6.1 Main features:
• High accuracy measurements.
• Fast download.
• Improved instrument design.
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• True USB speed and convenience
• Unique desiccant holder in the battery end cap.
• Store over 30 million readings internally (10 million C,T and D samples) .
• RS-232 and RS-485 support for telemetry and long cable usage.
• Longer deployments with eight CR123A batteries (optional extended body with 16 batteries).
• New microprocessor, real-time operating system, sophisticated power management, and USB
and serial connectivity.
• Mechanical redesign to reduce the complexity of the internal parts and more efficient use of
the space available.
• 6Hz and 12Hz fast sampling options for profiling
• Memory expansion to 60 or 120 million readings option
Conductivity - Measured with an inductive sensor, suitable for deployment in marine,
estuarine, or fresh water. There are no exposed contacts, which avoids susceptibility to
corrosion, and the housing may be frozen into ice without damage.
Temperature - The sensor is built and calibrated in-house using an aged thermistor. The
temperature channel is calibrated an accuracy of ± 0.002°C (ITS-90) over the range -5 to
+35°C. Extended range calibrations are available.
Pressure - Measured with a piezo-resistive transducer with nickel based super alloy
diaphragm to avoid corrosion. Accuracy is 0.05% of the full scale rating and achievable
resolution is 0.001%. The pressure sensor is available in a range between lOdbar to
740dbar. See the data sheet for possible sensor ratings.
The manufacturer's specifications for this instrument are included in Appendix A.
A.4.7 University of WA Applied Physics Lab (APL-UW) Sigma
Profiler
http://staff.washington.edu/aganse/mvresearch/sigmaProfiler/index.html
APL-UW has developed a remote sensing instrument - the "Sigma Profiler" (SP) - which
measures conductivity as a function of depth and time in the water column of an estuarine
environment.
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SP1&2 parallel source/receiver, 2.Sx6m SP3: in-line source/receiver, 2 revs 6 & 20m
Figure A-7
The Sigma Profiler is an APL-developed instrument prototype for remotely observing
estuarine salinity profiles via electromagnetic measurements. It was used repeatedly in the
Columbia River estuary in conjunction with nearby CTD profiles as part of the Center for
Coastal Margin Observation and Prediction program, which sponsored the instrument's
initial development.
The instrument's principle of operation is that electromagnetic waves are attenuated in
seawater as a function of frequency. Electrical currents at different frequencies are
produced by the instrument, and the resulting electric field is measured at a nearby dipole
receiver. These measurements can be combined to infer the conductivity (and hence
salinity) structure in the water column. Conductivity is the variable of focus from this tool
for sake of statistical rigor, but there is a nearly linear relationship to salinity in the estuarine
environment, so we can measure conductivity to directly obtain salinity with low error.
Regions of strong property gradients, such as those present at fronts of salinity intrusions
into a marine estuary, are of vital importance to the ecology of the estuary as well as the
quality of the drinking and irrigation water sourced from it. Previous technologies to
observe a salt wedge are subject to difficulties with: point sensors that are not
representative, maintaining sensors in strong current, bio-fouling and sedimentation, fish
attack and floating and submerged debris, damage from fishing and vessels and vandalism,
and costly sensors and batteries.
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APPENDIX B:
Flow Measurement Instrumentation
Equipment Overview, Comparison and
Manufacturers' Specifications
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B. Flow Measurement - Index Velocity
Instrumentation
B.1 Overview
Accurate measurement of flow in an open channel requires precise measurements of the
channel cross-section area and many independent velocity measurements taken across the
entire channel. Real-time flow measurements are typically taken with a type of meter that
only measures a portion of the channel velocity that is referred to as in Index Velocity (Vi).
An index equation is developed for the in-situ index velocity meter by conducting several
independent measurements of channel cross-section, stage and current velocity, which is
then used to calculate the average channel velocity (Va) from the measured index velocity.
The average velocity is multiplied by the channel cross-sectional area, determined from
measured stage, to calculate flow.
B.1.1 Acoustic Velocity Meter
Acoustic Velocity Meters (AVMs), also referred to as an Ultrasonic Velocity Meters
(UVM), are time-of-travel devices that measure water velocities along an acoustic path
between pairs of transducers located on a diagonal line across a channel. The transducers
are connected to a central processors by cables (Figure B-l). Acoustic pulses are
transmitted along the acoustic path; the upstream-moving (against current) pulses travel
slower than the downstream-moving (with current) pulses. The difference in travel time
between a pair of back and forth pulses provides an average velocity (Vp) across the
channel at the depth of the transducers. The measured velocity (Vp) is not an average cross-
sectional velocity and is referred to as an "index velocity" (Vi) that is used when processing
the data to determine an average cross-sectional velocity(VL). (Laenen, 1985).
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—P
centel mm
processor
.-rV'7''
y
transducer
Figure B-1 Acoustic Velocity Meter (AVM) Schematic (Laenen 1985)
B.1.2 Acoustic Doppler Current Profilers
Acoustic profilers use the Doppler frequency shift of acoustic pulses reflected from
particles in the water to measure water velocities in multiple sample cells. Profilers can be
mounted in a horizontal orientation (Figure B-2a) to measure velocity profiles across a
channel or mounted in a vertical orientation (Figure B-2b) to measure vertical velocity
profiles. A profiler uses two to four transducers set at a known orientation to measure water
velocities. Each transducer transmits sound pulses of a known frequency along a narrow
acoustic beam (Figure B-2). As the pulses travel along the acoustic beam, they strike
particulate matter (scatterers) suspended in the water. When the pulses strike scatterers
some of the sound is reflected along the acoustic beam to the transducer. The reflected
pulses have a frequency (Doppler) shift proportional to the velocities of the scatterers they
are traveling in along the acoustic beam.
Profilers measure velocities in uniformly-sized cells or bins along the acoustic beams
(Figure B-4). By measuring velocities in a number of bins across a channel or vertically
through the water column, these instruments produce horizontal or vertical water velocity
profiles, hence the designation "profiler." (Levesque 2012)
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(A) Horizontally-oriented profiler
(B) Vertically-oriented profiler
Figure B-2 Examples of Acoustic Doppler Profiler Orientations
I
Bin velocity
components
J~ **
^ ^Binvebcity
y components
Bknkirig
distance |
B.1.3 Flow Measurement by Acoustic Scintillation
In the mid-1990s, ASL AQFlow developed a new method for measuring the discharge in
low head, short intake power plants, the Acoustic Scintillation Flow Meter (ASFM).
Originally tested in rivers and ocean channels, the method uses the scintillation of an
acoustic signal transmitted along a path in a turbulent flow to measure the flow velocity.
This method may have some application in measuring the mean velocity across the channel
at a location like Chipps Island. Research application of this technology has been typically
applied with a single acoustic path, however the newer, well developed application of this
technology for use in intakes of hydroelectric dams has employed an array of vertical
sensors to provide accurate 2D velocities across short sampling paths. The application of
this technology to wide-channel flow is discussed in (Di Iorio and Barton 2003) and should
be considered as a possibility for future flow measurement in the Bay Delta.
Measurement principles
Acoustic scintillation drift is a technique for measuring flow in a turbulent medium by
analyzing the variations in ultrasonic pulses that have been transmitted through the
medium.
The Acoustic Scintillation Flow Meter (ASFM) uses this technique to measure the velocity
of the water flowing through a conduit (e.g. an intake to a hydroelectric turbine) by utilizing
the turbulence in the flow (e.g. small-scale turbulence generated by the intake trash racks).
With two transmitters placed at one side of the conduit, and two receivers at the other, the
signal amplitude at the receivers will vary randomly in time as the distribution of
turbulence along the propagation paths changes with time and the flow. If the paths are
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sufficiently closely spaced, the turbulence will remain embedded in the flow, and the
pattern of the variations (known as "scintillations") at the downstream receiver will be
nearly identical to that at the upstream receiver, except for a time delay, A (Fig 1). If these
scintillations are examined over a suitable time period, this time delay can be determined.
The mean flow velocity perpendicular to the acoustic path is then A.JAX. where A, is the
separation between the paths. Using three receivers in a triangular array allows both the
magnitude and inclination of the laterally averaged velocity to be measured.
The average velocity is measured at several pre-selected measurement levels. Total flow
rate is calculated by integrating the average horizontal component of the velocity at each
level over the total cross-sectional area of the conduit.
Di Iorio, D., and A. Barton, Path-averaged ocean measurements in the deep, stratified tidal
channel of Hood Canal using acoustical scintillation, J. Geophys. Res., 108(C10), 3312,
doi: 10.1029/2003JC001796, 2003.
Lemon D. D., S. F. Clifford and D. M. Farmer B. B. Parker "Scintillation current
measurements, a new approach to real-time current measurements in channels and
harbours", Applications of Real-time Oceanographic Circulation Modelling Symposium
Proceedings, 1986
Lemon, D. D. and D. M. Farmer, "Experience with a multi-depth scintillation flowmeter
in the Fraser estuary," Proc. of the IEEE Fourth Working Conference on Current
Measurement, Clinton, MD, pp. 290-298, April, 1990.
Clifford, S. F. and D. M. Farmer, "Ocean flow measurements using acoustic scintillation,"
J. Acoust. Soc. Amer., vol.74 (6), pp. 1826-1832, December, 1983.
Farmer, D. M. and S. F. Clifford, "Space-time acoustic scintillation analysis: a new
technique for probing ocean flows," IEEE J. Ocean. Eng., vol.OE-11 (1), January, 1986.
Farmer, D. M. and S. F. Clifford and J. A. Verrall, "Scintillation structure of a turbulent
tidal flow," J. Geophys. Res., vol. 92 (C5), pp. 5396-5382, May, 1987.
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B.2 Flow Measurement Instrumentation for Consideration
Table B-1
Flow Measurement Sensors for Consideration
Instrument
Description
Pros
Cons
Capital Cost
Sontek SL
S* ari«
The SonTek SL(Side-Looking ) is
a horizontally-oriented Acoustic
Doppler Current Profiler (H-
ADCP) It comes in 3 Models with
Range of 5,20 and 120 meters
Widely excepted and easy to use.
New versions have ability to
measure up to 128 velocity cells.
Low power electronics
Made for irrigation and
natural channels <120m
wide.
$10-12K*
SonTek IQ
\
V °\
\qJ^/
Up-Looking acoustic Doppler flow
meter made specifically for
measuring flow in irrigation and
natural channels. 3 models with
single-cell and profiling capability.
Measure flow, total volume, water
level and velocity.
Can collect flow and volume data
in as little as 8 cm (3 in) of water.
Self-contained all-in-one design.
Proprietary flow algorithms for
irrigation canals, natural streams
and pipes, SmartPulseHD
adaptive sampling. Self-
calibrating water level using
vertical acoustic beam and
pressure
Made for smaller irrigation
and natural channels Up-
looking design needs to be
mounted on the channel
bottom
S8.5K
SonTek ADP
Up-Looking Acoustic Doppler
Current Profiler (ADCP) available
in several frequencies (500, 1000,
1500kHz). Can be used on a boat
for real-time discharge monitoring
or bottom or buoy mounted for
collecting detailed vertical velocity
profiles.
Measured detailed vertical
velocity profiles with optional
CTD integration.
Can be used for moving boat as
well as autonomous deployment.
Pros/cons related to installation
needs and location.
For autonomous
deployment, Up looking
design needs to be mounted
on the channel bottom or a
mooring. Where velocity
directions are reliant on
internal compass.
$22-$28K
Depending on
model and
options.
S
I
8?.
TRDI
ChannelMaster
jlfP
The compact, flexible,
CHANNELMASTER is a
horizontally-oriented Acoustic
Doppler Current Profiler (H-
ADCP) designed to collect high-
accuracy water velocity, stage,
and discharge data for a wide
array of applications
Widely accepted. New versions
have ability to measure up to 128
velocity cells. Low power
electronics
1200 kHz -11K,
600kHz-$12K,
300kHz-$18K
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Table B-1
Flow Measurement Sensors for Consideration
Instrument
Description
Pros
Cons
Capital Cost
TRDI-ADCP
u J
Up-Looking Acoustic Doppler
Current Profiler (ADCP) available
in several frequencies. Can be
used on a boat for real-time
discharge monitoring or bottom or
buoy mounted for collecting
detailed vertical velocity profiles.
Availble in 300, 600 or 1200 kHz
models
Measured detailed vertical
velocity profiles.
Depending on model, can be
used for moving boat as well as
autonomous deployment.
Pros/cons related to installation
needs and location.
For autonomous
deployment, Up looking
design needs to be mounted
on the channel bottom or a
mooring. Where velocity
directions are reliant on
internal compass.
$25-$35K+
depending on
model and
options.
CODAR
RiverSonde
The RiverSonde® is a non-
contact radar-based monitoring
With 2 systems can measure 2D
velocity vectors of entire river
surface
Does not measure
subsurface flow. Can be
$25-$??K+ for a
(Single ? Dual
|
111
iHIav •
system providing continuous
surface cross-channel velocity
profiles for streams, channels,
and rivers.
affected by wind driven
surface velocities.
Advertised with a range of
250 to 300m. Although
Hugh Roarty from Rutgers
along with the ROWG tested
the unit in the Hudson
(-800-1000m) and were
able to get coverage by
raising the antenna very
high (like building height)
system)
depending on
model and
options.
ASL-AQ Flow
Acoustic
Scintillation
* Approximate price for meter, cable and top-side interface module
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B.2.1 SonTek Side-Looking "SL" Acoustic Doppler Current Profilers
http://www.sontek.com/productsdetail.php?SonTek--SL-Series-8
The SonTek Argonaut-SL and new SonTek®-SL Series SL1500/3000 are advanced
Doppler current profilers for water velocity measurement in a horizontal layer.
The SonTek-SL (known as the Side-Looker or "SL") is used to measure water velocity and
level in open channels. The SonTek-SL features accessories, mounting options, software,
and a variety of integration formats. Designed specifically for side mounting on bridges,
canal walls, or riverbanks, the SL can be used in small channels from a few meters to rivers
several hundred meters wide.
anc
Figure B-4 Sontek SL on Pier Mount
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B.2.1.1 PRODUCT FEA TURES
• Water Velocity and Level: Water velocity, level flow, and total volume-multiple
parameters from one instrument. Acoustic Doppler profile of velocity data and
acoustic water level offer the most accurate, reliable measurements.
• SmartPulseHD®*; An algorithm that looks at water depth, profiling range,
velocity, and turbulence, and then acoustically adapts to those conditions using
pulse-coherent, broadband, and incoherent techniques.
• Water Velocity Profiling: Customizable, flexible setup options to suit a variety of
applications. 3G models offer 128-cells for high-resolution and detailed profiles.
The manufacturer's specifications for this instrument are included below
B.2.2 SonTek Up-Looking "IQ" Acoustic Doppler Current Profilers
http://www.sontek.com/productsdetail.php?SonTek-IQ-Series-15
SonTek-IQ® Series flowmeters are designed for monitoring flows in canals, culverts,
pipes, and natural streams. Four velocity beams profile water velocity in 3-D - both
vertically and horizontally - ensuring complete coverage of the velocity field. The built-in
pressure sensor and vertical acoustic beam work in tandem to measure water level. Simply
input the channel geometry using the intuitive SonTek-IQ software and you are outputting
flow data in minutes.
Capable of working both in man-made as well as natural channel, the SonTek-IQ can
collect flow (area-velocity) and volume data in as little as 8 cm (3 in) of water. Its five-
beam pulsed Doppler design is Modbus, SDI-12, RS232 and Analog ready.
Atoftg Am team
(dowmtr«m)
Skew Bfim
- VcrtKjl
¦ Pretiur* Srmof
Figure B-5
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B. 2.2.1 PRODUCT FEA TURES
• Self-contained all-in-one design
• Proprietary flow algorithms for irrigation canals, natural streams and pipes
• Uses SonTek's exclusive SmartPulseHD adaptive sampling
• Self-calibrating water level using vertical acoustic beam and pressure
The manufacturer's specifications for this instrument are included below
B.2.3 SonTek Acoustic Doppler Profiler (ADR)
The SonTek ADP (Acoustic Doppler Profiler) is a high-performance, 3-axis (3D) water
current profiler. The ADP uses state-of-the-art transducers and electronics designed to
reduce side-lobe interference problems. This allows the ADP to make the very near-
boundary (surface or bottom) current measurements critical to shallow water applications.
The 1.5-MHz profiler is available as a Mini-ADP featuring a compact transducer head
designed for applications where small size is critical.
Q 7nr\rn
Figure B-6
B. 2 3.1 STANDARD FEA TURES
• 0.25, 0.5, 1.0, and 1.5-MHz models
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• Profiling ranges up to 180m
• Side-looking configurations for horizontal profiling
• Bottom Tracking & GPS input for moving boat applications
• Compass and 2-Axis Tilt Sensor
• Low power consumption
• Temperature sensor
• Low price
• Proven SonTek reliability
B. 2.3.2 OPTIONAL FEA TURES
• SeaBird MicroCat CT Sensor
• Optical Backscatter Sensor (OBS)
• Internal Recording
• Pressure Sensor (Strain Gage)
• Pressure Sensor (Frequency-RPT)
The manufacturer's specifications for this instrument are included below
B.2.4 Teledyne-RDI ChannelMaster Acoustic Doppler Current
Profilers
Horizontal Acoustic Doppler Current Profiler
The compact, flexible, and affordable CHANNELMASTER is a horizontally-oriented
Acoustic Doppler Current Profiler (H-ADCP) designed to collect high-accuracy water
velocity, stage, and discharge data for a wide array of applications. By leveraging Teledyne
RDI's BroadBand technology, Channel-Master allows you to obtain unmatched data
quality, even in low velocities and complex flows, where a single cell cannot provide
enough information.
The ChannelMaster's innovative design includes everything you need to collect high-
quality data. The standard unit comes equipped with temperature, pressure, pitch and roll
sensors, and a vertical beam.
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Figure B-7
B. 2.4.1 PRODUCT FEA TURES
• Accurate: Teledyne RDI Broadband technology allows for small cells and/or
short averaging sampling intervals.
• Robust: Collect highly accurate velocities even in difficult environments such as
slow flow or rapidly changing flow.
• Versatile: ChannelMaster offers a range of 1-128 user selectable cell sizes from
25 cm - 8m and profiling ranges from lift - 300m (frequency dependent).
• Sturdy: Comes standard with stainless steel mounting fixture.
B.2.4.2 APPLICATIONS
• Rivers, Streams, and Irrigation Canals: Monitor discharge and water level for a
variety of applications. The ChannelMaster easily integrates with a telemetry or
SCADA system, providing you with remote access to your data.
• Estuaries: Measure complex currents for environmental monitoring or circulation
model calibrations or verifications.
• Port and Harbors: Monitor currents to provide velocity information for vessel
maneuvering and safety
The manufacturer's specifications for this instrument are included below
B.2.5 TRDI Sentinel ADCP
The self-contained Sentinel is Teledyne RD Instruments' most popular and versatile
Acoustic Doppler Current Profiler (ADCP) configuration, boasting thousands of units in
operation in over 50 countries around the world.
By providing profiling ranges from 1 to 165m, the high-frequency Sentinel ADCP is suited
for a wide variety of applications. The lightweight and adaptable Sentinel is easily
deployed on buoys, boats, or mounted on the seafloor. Real-time data can be transmitted
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to shore via a cable link or acoustic modem, or data can be stored internally for short or
long-term deployments. The Sentinel is easily upgraded to include pressure, bottom
tracking, and/or directional wave measurement—for the ultimate data collection solution.
• Versatility: Direct reading or self-contained, moored or moving, the Sentinel
provides precision current profiling data when and where you need it most.
• Precision data: Teledyne RDI's patented BroadBand signal processing delivers
very low-noise data, resulting in unparalleled data resolution and minimal power
consumption.
• A four-beam solution: Teledyne RDI's patented 4-beam design improves data
reliability by providing a redundant data source in the case of a blocked or
damaged beam; improves data quality by delivering an independent measure
known as error velocity; and improves data accuracy by reducing variance in
your data.
The manufacturer's specifications for this instrument are included below
B.2.6 CODAR RiverSonde non-contact Radar Surface current meter
The RiverSonde® is a non-contact radar-based monitoring system providing continuous
surface cross-channel velocity profiles for streams, channels, and rivers. Data output from
this system can be used as an index velocity in conjunction with other data sets or as model
input for calculation of total water discharge. It can also be used for monitoring river
movement during flood events and in disaster planning.
Figure B-8
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Continuous Realtime Two-Dimensional Vector Maps
of Surface Current Velocity
see? a} f wo
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w
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o
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combined wrtti those from addAonal faerSondes to cie.r?e continuous
resume *ecWX mips of vuri«e extent velocity **)
direction. m s*n*W rrwv** *1 SetSonde, but on a $m»8ef scjte {sp*UMy
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Figure B-9
This system is designed for operation at river's edge, in populated or remote locations.
Robust hardware and software allow automated operation and data processing, even under
extreme weather and/or vessel traffic conditions when other in-situ devices routinely fail.
B.2.6.1 Ri verSo nde Fea tures:
• Convenient: Nothing in the water: a truly non-contact sensor. All hardware is
located on land close to river's edge.
• Reliable: All system hardware and software are developed by our own staff
specifically for continuous, long-term field operations, and consistent data
outputs.
• Remote Access: Data retrieval, system monitoring, parameter modifications and
even factory support are all conducted through remote system access.
(Communication link required)
• Low Power: RiverSondes low power consumption allow for working off-the-grid
with alternative energy sources.
• Cross-Platform Data Format: All data products are stored as ASCII files for
convenient data transfer to various computer platforms.
The manufacturer's specifications for this instrument are included below
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APPENDIX C:
Deployment Equipment Options
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C. Deployment Equipment Options
C.1 Platform & deployment method
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C.1.1 Navigation or Monitoring Station Pilings
Satellite
telemetry
Sonde
Figure C-1. Examples of Pier Mounted Monitoring Stations
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C.1.2 Docks and Bridge Piers
Figure C-2. TRDI and SonTek Side-Looking ADCPs mounted on movable pier mounts
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Figure C-3 Water Quality instrument in a wall-mounted PVC pipe well
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C.1.3 Riverbank Mount
Figure C-4
C.1.4 Bottom-Mounted Monitoring Platform
Figure C-5. Trawl and Debris Resistant ADCP Platform with Acoustic Pop-up Buoy
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v
C.1.5 Moored Buoy Monitoring Station
Buoy systems are available for various power, water depth, and onshore/offshore, lake
conditions. Nexsens, YSI and Axys all make Data buoys with integrated solar panels, data
telemetry and power management systems.
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Figure C-7 YSI Pisces High-Velocity River Current Buoy
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Figure C-8 YSI Buoy Vertical Profiling System
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C. 1.5.1 Flow-Through Water Quality Monitoring Station
Table C-1
New Developments in Water Quality Sensor Deployment Methods
New Technology
Benefit
Developer
Fixed or buoy-mounted
autonomous vertical
profiling systems
Mechanically raise and lower CTD sensors to measure the
entire water column
YSI
McClane
Integrated or add-on
inductive cable modems
Allow internally powered and logging sensors to
communicate with the surface over the mechanical mooring
cable w/o the need for an electrical power/communications
cable
RBR
Seabird
Add-on inductive cable
modems for any Serial
Sonde
Allow internally powered and logging sensors to
communicate with the surface over the mechanical mooring
cable w/o the need for an electrical power/communications
cable
Sound9
Systems
Small, handheld CTD
Specifications are similar to standard scientific CTD but are
smaller and less expensive (-$5500)
YSI
Castaway
Integrated Systems
Integrated power, telemetry, instrumentation systems on pre-
fabricated buoys with solar panels, batteries, radio or cellular
near-real-time Internet web data display software
YSI
NexSens
AXYS
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C.1.6 Mechanical Profilers
Mechanical profiling systems have the advantage of obtaining a complete vertical profile
of the water column, enabling EC or salinity or volume to be extrapolated, and minimize
some of the potential complications with having to have a cabled-bottom mounted sensor
that is subject to damage.
utomafed water quality maritarirTg and fok»m
~dicing 2+/7 wzft"ctfloI rig
13-11 i** 111 Jh iiiiiI i:iJ'vH-r Ii r
fr±J-vcltt'an:i rainc aT«ircnmiTi
Figure C-10 Buoy and Dock Mounted Mechanical Profilers
Piling Mounted Vertical Profiler system with Solar Panels $30,000
Pontoon - Vertical Profiling System 100m profiler $75,000.00
Buoy - Vertical Profiling System $80,000.00
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C.1.7 Buoy Systems
Figure C-11 Multipoint mooring buoy with CTD and up-looking ADCP
Vulnerability of a buoy to both vessel traffic and floating debris
Navigation issues with buoys: To ensure an Oceanographic Data Acquisition System ODAS buoy is
compliant to IALA regulations, it has been fitted with a 3-mile visible LED navigation light displaying
the Amber Gp F1 4 (20) flash sequence and a Firdell Blipper radar reflector. Another advanced feature on
a buoy that can increase awareness of this station to marine operators is the incorporation of an Automatic
Identification System (AIS) transmitter. This device will transmit a unique platform ID along with buoy's
GPS location and basic weather information. New shipping regulations are requiring vessels to receive
this AIS data onto their navigation systems.
YSI EMM700 - Bay Buoy 2 Sondes at fixed levels $31,800.00
C.1.8 Inductive Communication Modems
New technology. Allow internally powered and logging sensors to communicate with the
surface over a plastic-jacketed mechanical (metallic) mooring cable without the need for
an electrical power/communications cable.
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An inductive modem could be used for real-time data transmission from a near-bottom
sensor in locations where electro-mechanical cables would be damaged.
Seabird Underwater Inductive Modem Module (UIMM) is a quick way for system
integrators and instrument/sensor manufacturers to adapt new or pre-existing RS-232
instruments, such as acoustic current meters, Doppler profilers, optical sensors, etc., for
integration with real-time moorings using Sea-Bird's Inductive Modem (IM)
telemetrv.http://www.seabird.com/underwater-inductive-modem-module
The Soundnine Ulti-modem is an inductive modem with internal battery and integrated
coupler. It connects any serial device to inductive telemetry, including CTDs, current
meters and custom sensors. Innovative dual-mode communications allows both
compatibility with inductive modem products from Sea-Bird Electronics and high speed
communications (to 19200 baud) with modems from Soundnine. The plastic housing with
titanium faceplate is rated to 1000 meters depth. Typical battery endurance is three years.
http ://www. soundnine. com/ultimodem
http://www.rbr-global.com/products/mooring-line-modem. RBR's inductive modem
communication system, the MLM-1000, for XR and XRX series CTD (conductivity,
temperature and depth) loggers (sonde, recorder), for the DBC2 and for OEM applications
is designed to provide fast communication with loggers deployed up to a kilometre in
depth. The modem uses an underwater transformer to transmit information through a
Figure C-12 RBR, SeaBird and SoundNine inductive cable modems
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jacketed mooring line without requiring cables or connectors. Essentially an unlimited
number of instruments may be connected to the MLM-1000 and communication at 4800
baud is provided over an insulated mooring line of up to 1,000m length. Features include
transparent link and automatic node discovery. CRC error detection is included. The MLM-
1000 can drive RF. cellular, or satellite telemetry directly. The conductor loop is comprised
of the steel core of a jacketed mooring cable and sea or fresh water. The ends of the steel
cable are stripped of the insulating jacket and are thus in contact with the water. Between
the stripped ends of the cable, the water provides a conduction path for electric current.
Each system node typically uses a toroidal transformer that is clamped around the mooring
line. The magnetic coupling between the toroid and the mooring cable is the medium by
which information is transferred between the mooring cable and the particular system node.
Features
The ability to receive oceanographic measurement data from any one of a network of deployed RBR
logger instruments in "near real-time".
The ability to alter sampling regimes for already deployed logger instruments, for example in response to
changing marine environmental conditions.
The ability to gauge the status and functional health of deployed instruments.
The ability to download data from logger instrument memory while the instrument is deployed.
C.1.9 Pumped flow-through cells
Flow through cells can be used with pumping systems to sample near-bottom water without
having to have the sensor deployed at depth. They can help to greatly minimize cable
damage and biofouling.
Figure C-13
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C.1.10 Improved Wiped Conductivity Sensor
599827 YSIEX02 Wiped CT Sensor.
Improve the representativeness of your
conductivity data by avoiding stagnant readings
and reducing the impact of micro-environments
Reduce the need for post-processing data and
spend (ess time manually adjusting forfouling-
related sensor drift
Prevent common types of foulingfrom impacting
your valuable data, including; particulates, algae,
barnacles, a nd trapped gasscs.
YSl.com/Wl pedCT
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