Chesapeake Bay Watershed Model
Application & Calculation of Nutrient
& Sediment Loadings
•
Appendix D: Phase IV
Chesapeake Bay
Watershed Model
Precipitation &
Meteorological Data
Development &
Atmospheric
Nutrient
Deposition
Prepared by the
Modeling Subcomittee
of the
Chesapeake Bay Program
EPA 903-R-97-022
CBP/TRS 181/97
Recycled/Recyclable
Primed wiih Scy/CanoJa Ink on paper thai
contains al leasl 50% recyded liber
Chesapeake Bay Program
-------
903R97022
Principal Authors
Dr. Ping Wang
Maryland Department of Natural Resources
Chesapeake Bay Program Office
Annapolis, MD
Lewis C. Linker
United States Environmental Protection Agency
Chesapeake Bay Program Office
Annapolis, MD
Jennifer Storrick
Chesapeake Research Consortium, Inc.
Chesapeake Bay Program Office
Annapolis, MD
U. S. Environmental Protection Agency
Environmental Science Center
701 Mapes Road
Ft. Meade, MD 20755-5350
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Modeling Subcommittee Members
James R. Collier, Chairman of the
Subcommittee,
Program Manager
Water Resources Management Division
Washington, DC
Dr. Joseph Bachman
US Geological Survey
Towson, MD
Mark Bennett
Department of Soil and Water Conservation
Richmond, VA
Dr. Peter Bergstrom
Chesapeake Bay Field Office
US Fish & Wildlife Service
Annapolis, MD
Dr. Arthur Butt
Chesapeake Bay Office
VA Department of Environmental Quality
Richmond, VA
Brian Hazelwood
Metropolitan Washington Council of
Governments
Washington, DC
Dr. Albert Y.Kuo
VA Institute of Marine Science
Gloucester Point, VA
Lewis C. Linker, Coordinator of the
Subcommittee
US EPA Chesapeake Bay Program Office
Annapolis, MD
Alan Lumb
Hydrologic Analysis Support Section
USGS National Center MS 415
Reston, VA
Dr. Robert Magnien
MD Department of Natural Resources
Assessment Administration
Annapolis, MD
Dr. Ross Mandel
Interstate Commission on the Potomac
River Basin
Rockville, MD
Dr. Bruce Parker
National Oceanic and Atmospheric
Administration/NOS/OES33
Coastal & Estuarine Oceanography Branch
Silver Spring, MD
Kenn Pattison .
PA Department of Environmental Protection
Bureau of Water Quality Protection
Harrisburg, PA
Ron Santos
US Army Corps of Engineers
Baltimore, MD
Tom Stockton
MD Department of Environmental Resources
Watershed Modeling & Analysis Division
Annapolis, MD
Paul Welle
USDA Soil Conservation Service
Northeast National Technical Center
Chester, PA
-------
Table of Contents
Section Page
1 Introduction 1
2 Observed Meteorological Data Base Development 2
3 Observed Precipitation Data Base Development 13
4 Simulation of the Atmospheric Deposition of Nutrients 34
IV
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List of Figures
Figure Page
D.2.1 Phase IV Model Segments of the Chesapeake Bay Watershed 3
D.2.2 Meteorologic Regions and Principal Stations 4
D.3.1 Thiessen Polygon of Precipitation Stations 15
D.3.2 Precipitation Segments of Phase IV Watershed Model 16
D.3.3 Location of Hourly and Daily Precipitation Stations 17
D.4.1 3D Model Cells 45
D.4.2 Precipitation Regions for the 3D Model 46
D.4.3 Precipitation Regions of the 3D Model & Coastal Watershed Model 47
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List of Tables
Table Page
D.2.1 Stations Used to Develop 1992-1994 Regional Meteorological Data 2
D.2.2 Missing Data and Filling Method < 5
D.2.3 Monthly Correction Factors to Potential Evaporation 6
D.2.4 Comparison of Meteorological Data Development 8
D.3.1 Precipitation Stations and Theissen Weights for Precipitation Segments 18
D.3.2 Format of Input Files for PRECIP.exe Program 23
D.3.3 Summary of Precipitation Data 25
D.4.1 Average Annual Atmospheric Wet NO3 and Wet NH, Depositions for 34
the Phase IV Chesapeake Bay Watershed Model Precipitation Segments,
1984-1994
D.4.2.a Annual Wet Deposition of NO3 at NADP Sites 36
D.4.2.b Annual Wet Deposition of NH4 at NADP Sites 36
D.4.3 Average Annual Atmospheric Wet & Dry NO3 Atmospheric Deposition 37
Loading Rates
D.4.4 Phase IV Chesapeake Bay Watershed Model Precipitation Segments, 41
1984-1991 Average Annual Atmospheric Dissolved Organic Nitrogen
Atmospheric Deposition Loading Rates
DAS 1984-1994 Annual Average Atmospheric Nitrogen Deposition to 42
the Chesapeake Bay Watershed
D.4.6 Correspondence of Phase IV Chesapeake Bay Watershed Model 44
Precipitation Segments with the Chesapeake Bay Water Quality Model
Precipitation Regions
Dry/Wet NO3 Atmospheric Deposition for the Chesapeake Bay 48
Water Quality Model Precipitation Regions
VI
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Acronyms and Abbreviations,
CBPAS
CBPO
CRC
deg-F
DIP
DON
DSN
FORTRAN
HSPF
kg/ha
Ib/ac
Ib/ac-yr
mg/1
NADP
NOAA
OrN
OrP
ppn
RADM
STAC
USEPA
USGS
WDM
WSM
Chesapeake Bay Program Ak Subcommittee
Chesapeake Bay Program Office
Chesapeake Research Consortium
Degrees Fahrenheit
Dissolved Inorganic Phosphorus
Dissolved Organic Nitrogen
Data Set Numbers
Formula Translation
Hydrological Simulation Program-FORTRAN
Kilograms per hectare
Pounds per acre
Pounds per acre per year
Milligrams per liter
National Ak Deposition Program
National Oceanic and Atmospheric Administration
Organic Nitrogen
Organic Phosphorus
Precipitation (mm)
Regional Acid Deposition Model
Scientific and Technical Advisory Committee
United States Environmental Protection Agency
United States Geological Survey
Watershed Data Management
Watershed Model
VII
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Section D.I Introduction
Precipitation and meteorological data are the primary forcing functions in the Phase IV
Chesapeake Bay Watershed Model. Flow, nonpoint source loads, and reaction rates all primarily
depend on the continuous hourly input of precipitation,temperature, evaporation, and solar radiation.
Consequently, great care is used in the development of .the precipitation and meteorological data
base.
The Phase IV Chesapeake Bay Watershed Model requires continuous hourly input data for
the 1984 to 1995 simulation. Developing twelve years of hourly precipitation tune series is a
challenge. One of the first decisions encountered in precipitation time series development is the
choice between obtaining the greatest number of observed stations and obtaining the greatest
consistency in stations. If the greatest number of observed stations is used, many large gaps occur
in the data as stations became operative and enter the data set, or, as the stations are discontinued and
leave the data set. The possibility of introducing error due to the inconsistency of the precipitation
stations throughout the simulation is a concern. On the other hand, if consistency is an absolute
priority many stations will be eliminated due to data gaps.
In an effort to compromise, a total of 147 precipitation stations are used, of which 88 are
hourly and 59 are daily records of rainfall. Data gaps exist in these observed stations, but overall
the observed stations used are relatively continuous over the entire simulation period. A computer
program, PRECIP.exe, provides a technique to partially overcome the discontinuity of some station
within a segment by re-weighting the data with the exclusion of the station with the missing data.
All seven of the primary meteorological stations within or adjacent to the Chesapeake basin
are used, including Binghamton, NY, Williamsport, PA, Harrisburg, PA, Elkton, WV, Dullas
Airport, Richmond, VA, and Roanoake, VA. The work hi this phase of Watershed Model
development is expansion of the precipitation and meteorological data base from 1984-91 to 1984-
1995. Slightly different methods were used in the 1991-95 data development due to upgrades in
computer hardware and software, and a change from VMS/DOS to UNIX operating systems.
Specifically, in the 1984-91 database development the program NOAA.EXE was used to
transform the observed data into WDM file format. In the 1991 -95 database development, the newer
programs PREDY, PREHR and HSPF programs were used the develop WDM files. In the
meteorological data, various programs were used in the development of he 1984-91 WDM files
whereas in the 1991-95 WDM development the newer program USGS METCOMP was used. In
all cases the programs were designed for the same purpose and generated the same type of output.
To assess comparability between the 1984-91 and the 1991-95 data, a year of overlap 1991
data is used. The 1991 precipitation and meteorological data is developed under the two equivalent
methodologies and compared. No significant differences are discerned in the 1991 data generated
from either of the two methodologies.
-------
Section D.2 Observed Meteorological Data Base Development
The National Oceanic and Atmospheric Administration (NOAA) standard formatted daily
maximum air temperature, minimum air temperature, dew point temperature, cloud coverage, and
wind speed for 1991 -1994 were collected from seven stations for the seven meteorological regions
of the Phase IV Chesapeake Bay Watershed Model. Figure D.2.1 shows the Phase IV Watershed
Model segments. The seven meteorological regions and associated model segments are illustrated
on Figure D.2.2 and listed in Table D.2.1.
Table D.2.1.
Stations Used to Develop 1992-1994 Regional Meteorological Data
Region # Station # Location
1 • 04725 Binghamton, NY
2 14778 Williamsport, PA
3 14711 Middletown Harrisburg, PA*
4 13729 Elkins, WV
5 93738 Dulles Airport, VA
6 13741 Roanoke,VA
7 ' 13740 Richmond, VA
lb** ' 14768 Rochester, NY
2b** 14777 Wilkes-Barre/Scranton, PA
7b** 13733 Lynchburg AP, VA
* Note: The Harrisburg Station, PA was used in Phase II. However, data after 10/01/91 were no longer
available from the Harrisburg Station, PA so the Middletown Harrisburg Station, PA was used in Phase
IV (1992-1994). Therefore, for the intercomparison stage 1 and stage 2 data transformations, Phase IV
data for 1/91-9/91 were from Harrisburg and the 10/91-12/91 .data were from Middletown Harrisburg,
PA.
** Note: These stations were utilized as alternative stations to fill in any missing data for the
corresponding primary stations.
The NOAA formatted data were reformatted to the HYDDY format using dBase and a
FORTRAN program PREDY.F.1 A copy of this program is located at the end of this section. The
HYDDY format is a code including information such as the station number, year, month and data.
The format is generally encoded as follows:
1 Wang, P. (1995). Chesapeake Bay Program Office, Annapolis, MD.
2
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Figure D.2.1
Phase IV Chesapeake Bay Watershed Model Segments
LOCATION MAP
OFTHE
Chesapeake Bay Watershed
NY,PA,MD.D.C,DE.
WVANDVA
PW M^J Dale: June 20.1997 spoubome/pwang/sctup/ps/arcT/cov/ '
Source: USEPA Chesapeake Bay Program Office
-------
Figure D.2.2
Phase IV Chesapeake Bay Watershed Model
Meteorologic Regions and Principal Stations
LOCATION MAP
OF THE
Chesapeake Bay Watershed
NY.PA.MD.DC.DE.
WVANDVA
PW Map Pgg June 20.1997
Source: USEPA Chesapeake Bay Program Office
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HYDDY
1. Station identifier (7 digits)
2. Year (last two digits)
3. Month (two digits)
4. Card Number: 1 is for days 1-10
2 is for days 11-20
3 is for days 21up to 31
5. Ten fields, for the daily data (11 fields for the card number 3).
The HYDDY formatted data were then reformatted to Watershed Data Management (WDM)
format using the HSPF software. WDM files are the type used as input to the watershed model.
Data were inspected manually hi order to locate any possible missing data periods. The
missing data periods in some meteorological regions were filled hi manually by utilizing data from
nearby stations, as listed in Table D.2.2.
Table D.2.2
Missing Data and Filling Method
Region with
missing data
1
2
3
4
7
Missing
data type
Cloud cover
Cloud cover
Cloud cover
Cloud cover
Cloud cover
Missing
period
11/01/95-12/31/95
06/01/94-09/30/94
09/01/95-12/31/95
09/01/91-09/30/91
09/28/92-10/28/92
10/13/94-12/31/94
01/01/95-09/30/95
10/01/95-12/31/95
Region used for
filling data
lt>
1
2b
2
5
6
3b
The Metcmp software2 was used to retrieve the WDM formatted meteorological data in order
to generate the required input data hi HSPF format hi order to compute the following operations:
2 Flynn, K., Lumb, A. (1991). Computation and Modification of Meteorolgic Time Series. Version
1.1. United States Geological Survey, Water Resources Division, Reston, VA.
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a. Hourly air temperature was calculated from daily maximum and minimum air temperature.
b. Hourly wind speed was disaggregated from daily data.
c. Hourly solar radiation was generated using cloud coverage data and the regional latitudes.
d. Hourly potential evaporation was generated by applying the Penman method3 using daily
maximum air temperature, daily minimum air temperature, daily dew point temperature, daily wind
speed, and hourly solar radiation. Monthly correction factors to the potential evaporation for the
seven regions were estimated by examination of observed evaporation records and used on the
potential evaporation data calculated with the Penman method. Monthly correction factors are
tabulated in Table D.2.3.
Table D.2.34
Monthly Correction
Jan
1 0.555
R 2 0.548
E 3 0.562
G 4 0.569
I 5 0.562
O 6 0.562
N 7 0.540
Feb
0.593
0.585
0.601
0.608
0.601
0.601
0.608
Factors to Potential Evaporation
Mar
0.722
0.713
0.732
0.741
0.732
0.732
0.703
Apr
0.851
0.840
0.862
0.874
0.862
0.862
0.829
May
0.889
0.878
0.901
0.913
0.901
0.901
0.866
Jun
0.912
0.900
0.924
0.936
0.924
0.924
0.888
Jul
0.912
0.900
0.924
0.936
0.924
0.924
0.888
Aug
0.897
0.885
0.909
0.920
0.909
0.909
0.873
Sep
0.836
0.825
0.847
0.858
0.847
0.847
0.814
Oct
0.745
0.735
0.755
0.764
0.755
0.755
0.725
Nov
0.646
0.638
0.655
0.663
0.655
0.655
0.629
Dec
0.562
0.555
0.570
0.577
0.570
0.570
0.548
Test for Consistency Between the 1984-91 and 1991-1995 Data Sets
The program ANNIE.exe5 was used to export the hourly air temperature, wind speed, solar
radiation, cloud coverage, and potential evaporation data from both (a) the WDM file which was
generated in the above process (for 1991-1995), and (b) the WDM file which was developed in stage
3Viessman, W., Lewis, G.L., and Knapp, J.W. (1989). Introduction to Hydrology. Harper & Row
Publishers. New York.
4 Provided by Aqua Terra Inc.
5 Lumb, A.M., Kittle, J., and Flynn, K.M. (1990). Users Manual for ANNIE, A Computer Program for
Interactive Hydrologic Analyses and Data Management. U.S. Geological Survey. Reston, Virginia.
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1 (for 1984-1991) to insure the consistency between them. The HSPF software was used to process
the 1991 meteorological data from these two Phases by summing up the daily values to yield a
monthly summation. The results are summarized hi Table D.2.4.
Table D.2.4 shows that the 1984-1991 and 1991-1995 methodologies are entirely consistent
- most with <0.01 % difference, although up to 1 -2% difference in the monthly values summed from
the daily data are observed. These differences may be due to the different methods in calculation,
particularly for solar radiation, which in turn affects the calculation of evaporation.
Based on the above analysis documenting the consistency of data from the two
methodologies, the 1992-94 data were combined with the 1984-91 data using the ANNIE.exe
software.
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Table D.2.4
Comparison of Meteorological Data Development for Stage 1 and Stage 2
Region I (monthly averages from daily data in 1991)
Stage 1
Date
Jan-91
Feb-91
Mar-91
Apr-91
May-91
Jun-91
Jul-91
Aug-91
Sep-91
Oct-91
Nov-91
Dec-91
Evapor.
(inch)
0.0258
0.0348
0.0740
0.1488
0.2189
0.2576
0.2357
0.1986
0.1473
0.0939
0.0456
0.0291
Dew Point Cloud Cov
(degF)
16.4355
20.5714
25.7164
35.8694
50.5161
52.7861
56.5323
58.6935
48.1903
40.5390
30.0264
23.1129
(AID)
7.7419
7.6429
7.2258
7.0000
5.6774
5.8000
6.2903
5.9677
5.4667
6.5806
7.8667
7.7419
Wind Speed
(meters/hr)
265.4704
248.5714
271.1962
248.6389
218.7903
211.5972
205.7796
2152285
2182361
2382258
231.7639
263.1452
SolarRad
(Langleys)
123.9651
182.2173
248.5887
336.9861
484.4220
5122778
442.8226
404.0457
352.4444
233.4946
131.1333
110.4005
MaxTemp •
(degF)
30.4194
36.0357
43.6774
58.4000
72.4839
77.4000
80.5161
79.0000
69.5667
61.3226
46.2667
37.0968
MinTemp
(degF)
16.5161
20.7857
28.2258
39.8667
50.9677
55.8667
59.7097
59.3871
48.4333
41.4516
32.0333
23.2258
AirTemp
(degF)
23.1707
28.1875
35.5981
48.7986
61.3091
66.1611
69.6895
68.6882
58.5917
50.9261
38.8125
29.7460
Stage 2
Jan-91
Feb-91
Mar-91
Apr-91
May-91
Jun-91
Jul-91
Aug-91
Sep-91
Oct-91
Nov-91
Dec-91
0.0256
0.0341
0.0723
0.1461
0.2166
0.2552
02331
0.1950
0.1432
0.0914
0.0448
0.0286
16.1707
20.5432
25.7164
35.8694
50.5161
52.7861
56.5323
58.6935
48.1903
40.5390
30.0264
23.1129'
7.7419
7.6429
72258
7.0000
5.6774
5.8000
6.2903
5.9677
5.4667
6.5806
7.8667
7.7419
265.4704
248.5714
271.1962
248.6389
218.7903
211.5972
205.7796
2152285
2182361
238.2258
231.7639
263.1452
113.1989
171.0714
236.0215
'326.3056
478.0914
506.2361
435.9409
394.6505
338.6528
220.4301
121.0111
99.2460
30.4194
36.0357
43.6774
58.4000
72.4839
77.4000
80.5161
79.0000
69.5667
61.3226
46.2667
37.0968
16.3226
20.7857
282258
39.8667
50.9677
55.8667
59.7097
59.3871
48.4333
41.4516
32.0333
23.2258
23.0645
28.1860
35.5981
48.8000
61.3065
66.1597
69.6895
68.6855
58.5903
50.9220
38.8097
29.7487
Region II (monthly averages from daily data in 1991)
Stage 1
Stage 2
Date
Jan-91
Feb-91
Mar-91
Apr-91
May-91
Jun-91
Jul-91
Aug-91
Sep-91
Oct-91
Nov-91
Dec-91
Jan-91
Feb-91
Mar-91
Apr-91
May-91
Jun-91
Jul-91
Aug-91
Sep-91
Oct-91
Nov-91
Dec-91
Evapor. Dew Point Cloud Cov
(inch)
0.0307
0.0452
0.0860
0.1214
02148
0.2534
0.2276
0.1927
0.1240
0.0802
0.0485
0.0344
0.0307
0.0451
0.0855
0.1210
0.2148
0.2528
0.2274
0.1922
0.1229
0.0796
0.0484
0.0342
(degF)
19.0296
22.4033
30.0027
40.0139
53.6519
56.0764
60.7258
62.0000
52.8833
45.2003
31.4000
24.5712
18.9261
22.4033
30.0027
40.0139
53.6519
56.0764
60.7258
62.0000
52.8833
45.2003
31.4000
24.5712
(rtO)
7.0968
7.6786
7.1613
7.9667
6.3226
5.9667
6.4194
6.0645
5.9333
6.4839
7.7333
7.2581
7.0968
7.6786
7.1613
7.9667
6.3226
5.9667
6.4194
. 6.0645
5.9333
6.4839
7.7333
7.2581
Wind Speed
(meters/hr)
199.1263
214.1964
240.3898
211.2778
1612634
148.4028
1452419
128.5161
134.1597
183.7097
193.3611
202.3790
199.1263
214.1964
240.3898
211.2778
161.2634
148.4028
145.2419
128.5161
134.1597.
183.7097
193.3611
202.3790
SolarRad
(Langleys)
142.9973
183.3036
255.5511
284.6111
475.1478
508.2778
438.9785
412.8091
346.5417
251.4516
144.9167
123.2070
140.7527
181.5476
252.5269
282.5556
475.0941
506.8333
438.1855
411.6129
343.1528
248.6022
143.4444
1202325
MaxTemp
(degF)
36.8387
42.7143
51.4194
62.9000
81.0968
86.1000
87.9032
86.3871
74.5333
65.6774
50.3000
42.0968
36.8387
42.7143
51.4194
. 62.9000
81.0968
86.1000
87.9032
86.3871
74.5333
" 65.6774
50.3000
42.0968
MinTemp
(degF)
19.4516
24.7500
32.0323
41.1667
53.0323
57.0667
62.4839
61.5806
50.7333
42.7742
33.6000
25.9355
19.4516
24.7500
32.0323
41.1667
53.0323
57.0667
62.4839
61.5806
50.7333
42.7742
33.6000
25.9355
AirTemp
(degF)
27.7728
33.3839
41.3468
51.6056
66.5296
70.9486
74.6505
73.3978
62.1542
53.6680
41.6278
33.5202
27.7702
33.3824
41.3454
51.6042
66.5255
70.9458
74.6492
73.3952
62.1514
53.6680
41.6264
33.5094
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Table D2.4
Comparison of Meteorological Data Development for Stage 1 and Stage 2
Region III (monthly averages from daily data in 1991)
Stage 1
Stage 2'
Region
Stage 1
Stags 2
Date
Jan-91
Feb-91
Mar-91
Apr-91
May-91
Jun-91
Jul-91
Aug-91
Sep-91
Oct-91
Nov-91
Dec-91
Jan-91
Feb-91
Mar-91
Apr-91
May-91
Jun-91
Jul-91
Aug-91
Sep-91
Oct-91
Nov-91
Dec-91
E vapor.
(inch)
0.0343
0.0550
0.0981
0.1471
0.2425
0.2880
0.2464
0.2218
0.1337
0.1008
0.0618
0.0405
0.0347
0.0561
0.0989
0.1481
0.2440
0.2883
0.2475
0.2236
0.1349
0.0983
0.0545
0.0401
Dew Point
(degF)
0.1895
0.2098
0.1895
0.1958
0.1895
0.1958
0.1895
0.1895
0.1958
0.1895
0.1958 '
0.1895
0.1895
0.2098
0.1895
0.1958
0.1895
0.1958
0.1895
0.1895
0.1958
0.1895
0.1958
0.1895
Cloud Cov
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Table D.2.4
Comparison of Meteorological Data Development for Stage 1 and Stage 2
Region VI (monthly averages from daily data in 1991)
Stage 1
Date Evapor. Dew Point Cloud Cov Wind Speed
(inch) (degF) (/ID) (meters/hr)
Oct-91 0.1337 42.5806 4.1935 161.0349
Nov-91 0.0739 30.7833 6.1000 183.6806
Dec-91 0.0549 28.4651 5.4516 199.5833
SolarRad MaxTemp MinTemp • AirTemp
(Langleys) (degF) (degF) (degF)
338.9113
199.9306
170.0806
73.5161
57.2667
5Z7742
45.2581 58.6976
36.3333 46.4444
31.8710 41.7272
Stage 2
Oct-91
Nov-91
Dec-91
0.1384
0.0763
0.0564
42.5806
30.7833
28.4651
4.1935
6.1000
5.4516
161.0349
183.6806
199.5833
355.9946
217.0417
185.9005
73.5161
57.2667
52.7742
45.2581 58.6573
36.3333 46.4444
31.8710 41.6989
Region VII (monthly averages from daily data in 1991)
Stage 1
Date
Oct-91
Nov-91
Dec-91
Evapor. Dew Point Cloud Cov Wind Speed
(inch) (degF) (/10) (meters/hr)
0.1021 48.7513
0.0675 37.5764
0.0481 32.8844
5.3548 158.7097
6.1000 203.4444
5.1290 205.7796
SolarRad MaxTemp MinTemp AirTemp
(Langleys) (degF) (degF) {degF)
301.6532 72.7419
210.5139 60.8667
189.0995 55.2581
46.9677 595487
38.1667 49.1056
33.2258 43.6331
Stage 2 Oct-91 0.1026 48.7513
Nov-91 0.0682 37.5764
Dec-91 0.0484 32.8844
5.3548 158.7097
6.1000 203.4444
5.1290 205.7796
303.7634 72.7419
214.6944 60.8667
191.9892 55.2581
46.9677 59.2097
38.1667 49.1042
33.2258 43.6599
The numbers in Table D.2.4 are only for the purpose of comparing the agreement of stage 1 and stage 2 data processes. Although the values of
intensive variables such as wind speed cannot be simply added to represent the sum of the wind speed in the month, here they were summed up
merely to show their values in these two phases for comparison. Therefore, the units should be ignored for the summation in the output files. The
units in Table D.2.4 are the units for the houriy or daily Data Set Numbers (DSN) of WDM files.
For Regions 4,5,6, and 7, the 1/91-9/91 data were not reported in Table D.2.4 because there were some missing data during 1/91-9/91 for these
regions, and the missing data were filled in with the nearby stations' data. The stations used to fill in the missing data may be different
between stage 1 and stage 2. Therefore, it is not accurate to use the data within the periods with missing data as a base to verify the
consistency between the two phases of data development. For the stage 1 and stage 2 data verification, only 10/91-12/91 data were processed
for Regions 4,5,6, and 7.
10
-------
The following is a copy of the PREDY.F program utilized to reformat the NOAA formatted
dairy data into the HYDDY format hi order to make the data compatible with the HSPF
software so that it may be inputted into the Phase IV Chesapeake Bay Watershed Model.
character* 1 2 filtat(3), filin, filnam, filin2, filog
character*3 rectypl
character*8 stnid
character* 4 elmtypl; stnid
character*2 eunitl, state, stnidl
character*! flagl 1(100), flag21(100),typ, stal
character*5 stdumyl
dimension idayl(100),ihourl(100),ivaluel(100), value(31)
dimension isumyr(3), isumv2(3), iy(3), iso( 100,4)
dimension isumv3(3), isumv4(3), my(3), PP(1 100,4)
isumv2=0
isumv3=0
isumv4=0
PP = 0
Write(*,*)'Data extraction from NOAA Daily data1
WriteCVyreformat for HSPF runs'
filin2 = 'predy.lis'
open (8, file=filin2, access^sequential'jStatus^old1)
read(8,*) nfil
read(8,66) filin
66 format(al2)
open (10, file=filin, access- sequential^status^old1)
filnam = 'xxxxxxx.out'
filog = 'xxxxxxx.log1
rewind(lO)
ciose(lO)
typ =
i2 = 2
i3 = 3
LR = 0
line = 0
do 200 m= 1,1 00
line = line - 1
open (10, file=fiiin, access- sequential',status='old')
200 read(10,39,end=49,err=49)rectypel
39 format(a3)
33 format (a3, al , a2, a5, a4, a2, i4, i2, i2, i2; i2
11
-------
49 write(*,*) line
filnam(l:7) =
filog(l:7) =
open(24,FILE=filnam,STATUS='unknown')
open (10, file=filin, access-sequential',status='old')
do 100m=l,line
read(10,33, end=301, err=301) rectypl, stal, stnidl, stdumyl,
* elmtypl, eunitl, iyearl, imonl, ifill, inum, numvl,
* (idayl(j), ihourl(j),
* ivaluelG),flagll(j),flag21G)J = l,31)
40 iyr = iyearl -1900
do 53 k= 1,31
if(abs(ivaluel(k)) .gt. 99998) then
ivaluel(k) = -999
endif
53 continue
do 55 k= 1,31
value(k) = float(ivaluel(k)) / 100.
55 continue '
if(stal .eq. '18') state='MD'
if(stal .eq. '36') state='PA'
if(stal .eq. '44') state='VA'
if(stal .eq. '46') state='WV'
if(stal .eq. '07') state='DE'
if(stal .eq.'18') state='MD'
if(stal .eq. '30') state='NY1
write(24,205) stnidl, stdumyl, iyr, imonl, il,
1 (valueG)J=l,10)
write(24,205) stnidl, stdumyl, iyr, imonl, i2,
1 (value(j),j=ll,20)
write(24,207) staid 1, stdumy 1, iyr, imon 1, i3,
1 (valueO),j=21,31)
300 continue
100 continue
301 continue
close(lO)
close(24)
666 continue
205 format(a2, a5, i2, i2, il, 10f6.2)
207 format(a2, a5, i2, i2, il, 1 If6.2)
end
12
-------
Section D3 Observed Precipitation Database Development
The basic procedure for stage 2 precipitation data development follows the stage 1 method.
Hourly stations and daily stations were selected in reference to stage 1. The stage 1 stations were
selected based upon their locations within or near the boundary of the Chesapeake Bay watershed.
Due to discontinuity in the operation of individual precipitation stations, data from 88 stations and
59 daily precipitation stations ( a total of 147 stations) were used in stage 2 database development
compared with data from 155 precipitation stations used in stage 1. The data were formatted to
Watershed Data Management (WDM) file format.
Data from selected stations were reviewed hi an effort to guarantee the integrity of the data.
These verified NOAA formatted daily precipitation data sets were then converted to the HYDDY
format as previously described (see page 2). The hourly data were reformatted into the HYDHR
format using the FORTRAN program PREHR. A copy of this program is found at the end of this
section. The conversion for the HYDHR format is as follows:
HYDHR
1. Station identifier (10 digits)
2. Year (last two digits)
3. Month (two digits)
4. Day (two digits)
5. Card number: 1 is for a.m. hours
2 is for p.m. hours
6. Twelve fields for hourly data.
The HSPF software was utilized to reformat both the HYDDY and HYDHR formats into the
WDM format. At this point the files were then applied to the PRECIP.exe program together with
information from the Thiessen Polygon network of precipitation stations. The Thiessen polygon
network of precipitation is illustrated in Figure D.3.1. The Thiessen polygon method was chosen
for this data analysis because it makes it possibleto aerially weight the rainfall from each gage. This
method is exceptionally useful in those situations in which the stations are not uniformly distributed
and when the variations in rainfall amounts are relatively large in comparison to the mean. Although
the Thiessen polygon method is the most widely used, it does not account for any elevations effects
upon the precipitation distribution. The Thiessen polygon network is created by first drawing lines
that connect the stations on a map. In order to form polygons around each gage, perpendicular lines
are drawn on the map so that they bisect the before mentioned lines between the stations. Each
stations weighted rainfall is calculated as the ratio of the area of each polygon within the model
segment boundary to the total area6.
6Bedient, P.B., Huber, W.C. (1992). Hydrology andFloodplain Analysis. 2nded Addison-Wesley
Publishing Co., New York: 26-27.
13
-------
The precipitation segments'illustrated in Figure D.3.2, are primarily based upon the Phase
IV Chesapeake Bay Watershed Model Segments (Figure D.2.1). Since some of the model segments
were too small to have sufficient hourly stations fall within them, some aggregation, determined by
the number of hourly precipitation stations, of model segments occurred to form precipitation
segments.
The location of hourly and daily precipitation stations are shown in Figure D.3.3. Each
station was assigned a DSN number for WDM file development. A Thiessen polygon network was
generated using Arc/Info with the geographical locations of precipitation stations.
The resultant Thiessen polygon network (Figure D.3.1) and Phase IV Watershed Model
segmentation (Figure D.3.2) were overlapped to calculate the measurement of Thiessen polygon
distribution within a precipitation segment, and then the area! percentage of each Thiessen polygon
in a precipitation segment. Table D.3.1 lists precipitation stations and their areal percentage weights
for each precipitation segment.
Some of the areal percentage weights were converted to zero, because these stations actually
had no precipitation data during 1991-1994 and they were not included in the input files when
running the PRECIP.exe program. It is also acceptable for the calculation if the weight percentage
still keeps the measured areal percentage in a precipitation segment.
Additional adjustment to the Thiessen polygon network was required for precipitation
segments 60, 80 and 100. All three of these segments had more than ten hourly stations falling
within their boundaries. The PRECIP.exe program allows a maximum often hourly stations for
the calculation of estimated precipitation. As a result, the data were manually inspected and
stations with the least information based on the period of operation or Thiessen weight were
selectively culled.
Precipitation segments 700 and 750 are small segments with only three hourly precipitation
stations each. Data from all six stations were missing for April 1994. Precipitation stations near
segments 700 and 750 were selected and a new Thiessen polygon network was developed, which
was then overlapped with both segments. The exposed area was used for Segments 700 and 750
to calculate April 1994 precipitation.
The weight for precipitation stations in segments were then used to generate the input files
(as the weight of precipitation contributing to certain segment) for PRECIP.exe program. The
PRECIP.exe program read the input file (with ".inp" extension) and read from and wrote to the
WDM. Table D.3.2 is the format for input files.
The PRECIP.exe program operates by calculating the sum of a single day's precipitation
using the respective weights for both hourly (hourly precipitation is summed to a daily value) and
daily DSNs. The total daily weighted volume was then compared against the hourly stations total
daily volumes. The hourly station that had a total daily volume closest to the weighted volume was
u
14
-------
Figure D.3.1
Thiessen Polygon of Phase IV Chesapeake Bay
Watershed Model Precipitation Stations
Source: USEPA Chesapeake Bay Program Office
15
-------
Figure D.3.2
Phase IV Chesapeake Bay Watershed Model
Precipitation Segments
LOCATION MAP
OF THE
Chesapeake Bay Watershed
NY.PA.MD.DC.DE.
WVANDVA
PW Map Dae June 20,1997
Source: USEPA Chesapeake Bay Program Office
16
-------
Rgure D.3.3
Location of Hourly and Daily Precipitation Stations
Used in the Phase IV Chesapeake Bay Watershed Model
Hourly Precipitation Station
Daily Precipitation Station
PW Map Dale June 20.19»7
Source: USEPA Chesapeake Bay Program Office
17
-------
Table 0.3.1
Precipitation Stations and Their Weights for Precipitation Segments
Precip Model DSN Station
Segment Segment Name
Station Observation
Weight Time **
(If daily)
Precip Model DSN Station
Segment Segment Name
Station Observation
Weight Time
(if daily)
10
20
30
40
50
101
9
10
18
20
108
142
152
160
179
336
20 1
2
3
5
11
15
16
17
19
22
300
30 108
117
130
'141
142
147
170
173
181
187
300
315
40117
124
149
166
177
187
141*
146*
181*
999*
284
315
50113.
114
116
133
134
155
NYHR0270 '
NYHR3979
NYHR3983
NYHR8498
NYHR9229
PAHR1212
PAHR5731
PAHR6627
PAHR7310
PAHR8868
PADY9408
NYHR0270
NYHR0687
NYHR1987
NYHR2454
NYHR4070
NYHR5682
NYHR6685
NYHR7830
NYHR8625
NYHR9522
PADY7029
PAHR1212
PAHR2325
PAHR3521
PAHR5601
PAHR5731
PAHR5915
PAHR8275
PAHR8491
PAHR8905
PAHR9705
PADY7029
PADY8057
PAHR2325
PAHR3018
PAHR6004
PAHR7931
PAHR8763
PAHR9705
PAHR5601
PAHR5825
PAHR8905
XXHROOOO
PADY5817
PADY8057
PAHR1961
PAHR2245
PAHR2298
PAHR4001
PAHR4027
PAHR6916
0.0492
0.1692
0.1550
0.1353
0.0995
0.0386
0.0733
0.1006
0.0162
0.1309
0.0322
0.0508
0.0851
0.1872
0.1015
0.0621
0.0649
0.2057
0.0849
0.0711
0.0780
0.0087
0.0682
0.1176
0.0037
0.0248
0.0152
0.2108
0.0449
0.0850
0.1797
0.1966
0.0261
0.0274
0.0397
0.0354
0.1809
0.1054
0.0824
0.0229
0.0001
0.0001
0.0001
0.0001
0.2045
0.3284
0.4211
0.0171
0.0018
0.0730
0.0177
0.2206
07:00
08:00
08:00
07:00
07:00
07:00
60
70
80
90
159
175
999*
333
60101
113
117
120
146
152
1.55
160
168
999*
268
274
283
306
323
336
342
70 108
117
166
2*
142*
147*
155*
181*
101*
999*
268
274
284
342
80 104
105
109
123
146
• 149
166
177
999*
196
268
269
283
289
345
90116
122
PAHR7217
PAHR8589
XXHROOOO
PADY9022
PAHR0147
PAHR1961
PAHR2245
PAHR2629
PAHR5825
PAHR6627
PAHR6916
PAHR7310
PAHR8155
XXHROOOO
PADY4853
PADY5109
PADY5790
PADY7409
PADY8469
PADY9408
PADY9728
PAHR1212
PAHR2325
PAHR7931
NYHR0687
PAHR5731
PAHR5915
PAHR6916
PAHR8905
PAHR0147
XXHROOOO
PADY4853
PADY5109
PADY5817
PADY9728 ,
PAHR0725
PAHR0763
PAHR1354
PAHR2838
PAHR5825
PAHR6004
PAHR7931
PAHR8763
XXHROOOO
PADY0482
PADY4853
PADY4896
PADY5790
PADY6297
PADY9950
PAHR2298
PAHR2721
0.0102
0.1344
0.0001
0.1040
0.0594
0.0314
0.0022
0.1034
0.0172
0.0001
0.0730
0.0669
0.0533
0.0001
0.0001.
0.1330
0.0370
0.1304
0.0704
0.1486
0.0751
0.0517
0.2471
0.1115
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.1038
0.0005
0.1493
0.3354
0.0581
0.1457
0.0468
0.0371
0.0288
0.1125
0.0880
0.0101
0.0001
0.1146
0.0594
0.0368
0.0635
0.1984
0.0001
0.1455
0.4343
07:00
17:00
07:00
07:00
08:00
08:00
07:00
24:00
17:00
07:00
07:00
24:00
07:00
17:00
15:00
07:00
07:00
08:00
18
-------
Table D.3.1
100
110
120
lei
men:
100
110
120
DSN
t.
127
133
161
608
134*
175*
502*
999*
312
104
105
109
113
116
133
146
155
161
999*
196 -
268
273
281
283
289
312
103
119
123
149
189
109*
137*
138*
999*
269
305
320
345
129
137
138
189
103*
119*
177*
601*
615*
999*
253
Station
Name
PAHR3295
PAHR4001
PAHR7312
MDHR4030
PADY4027
PADY8589
WVHR1323
XXHROOOO
PADY7846
PAHR0725
PAHR0763
PAHR1354
PAHR1961
PAHR2298
PAHR4001
PAHR5825
PAHR6916
PAHR7312
XXHROOOO
PADY0482
PADY4853
PADY4992
PADY5662
PADY5790
PADY6297
PADY7846
PAHR0605
PAHR2537
PAHR2838
PAHR6004
PAHR9938
PAHR1354
PAHR4763
PAHR4778
XXHROOOO
PADY4896
PADY7322
PADY8379
PADY9950
PAHR3321
PAHR4763
PAHR4778
PAHR9938
PAHR0605
PAHR2537
PAHR8763
MDHR0015
MDHR9030
XXHROOOO
PADY4019
Station
Weight
0.0683
0.0002
0.0887
0.0003
0.0001
0.0001
0.0001
0.0001
0.2623
0.0983
0.0034
0.0000
0.0001
0.0075
0.1737
0.0781
0.0700
0.2221
0.0001
0.0344
0.0001
0.1453
0.0000
0.0029
0.0754
0.0887
0.0078
0.0051
0.0686
0.0613
0.0981
0.0001
0.0001
0.0001
0.0001
0.2693
0.0051
0.2391
0.2452
0.1758
0.3912
0.0037
0.0021
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.4266
Observation
Time
(if daily)
07:00
07:00
17:00
08:00
08:00
07:00
07:00
07:00
15:00
07:00
08:00
09:00
07:00
Precip Model DSN Station
Segment Segment Name
160
160 122 PAHR2721 0.0028
127 PAHR3295 0.1818
503 WVHR1393 0.0112
509 WVHR6163 0.0630
Station Observation
Weight Time
(if daily)
170
175
180
190
510
116*
175*
502*
608*
999*
516
633
662
170502
503
508
509
510
707
724
127*
999*
516
525
535
633
813
175122
127
502
508
509
510
608
737
707*
999*
544
633
856
180 109
123
505
605
119*
123*
502*
742*
999*
623
640
643
818
190 707
722
726
737
742
WVHR7730
PAHR2298
PAHR8589
WVHR1323
MDHR4030
XXHROOOO
WVDY0527
MDDY2282
MDDY8065
WVHR1323
WVHR1393
WVHR5739
WVHR6163
WVHR7730
VAHR2208
VAHR5880
PAHR3295
XXHROOOO
WVDY0527
WVDY3215
WVDY6960
MDDY2282
VADY5595
PAHR2721
PAHR3295
WVHR1323
WVHR5739
WVHR6163.
WVHR7730
MDHR4030
VAHR8046
VAHR2208
XXHROOOO
WVDY9281
MDDY2282
VADY9186
PAHR1354
PAHR2838
WVHR4763
MDHR1530
PAHR2537
PAHR2838
WVHR1323
VAHR8396
VAHROOOO
MDDY1032
MDDY3355
MDDY3975
VADY5851
VAHR2208
VAHR5690
VAHR6178
VAHR8046
VAHR8396
0.1001
0.0001
0.0001
0.0001
0.0001
0.0001
0.1672
0.2188
0.2546
0.0001
0.0475
0.0253
0.1684
0.1050
0.0026
0.0004
0.0001
0.0001
0.0057
0.3803
0.1973
0.0040
0.0632
0.0625
0.0094
0.1985
0.0955
0.0400
0.1269
0.1330
0.0410
0.0001
0.0001
0.2035
0.0884
0.0011
0.0543
0.0103
0.2589
0.1778
0.0001
0.0001
0.0001
0.0001
0.0001
0.0400
0.1377
0.2429
0.0776
0.3168
0.0548
0.0051
0.0080
0.0011
07:00
07:00
08:00
07:00
08:00
08:00
07:00
07:00
08:00
07:00
08:00
18:00
07:00
18:00
08:00
508* WVHR5739 0.0001
19
-------
Table D.3.1
Precip Model DSN Station
Segment Segment Name
Station Observation
Weight Time
(if daily)
Precip Model DSN Station
Segment Segment Name
200
210
220
230
724*
729*
503*
999*
525
760
807
836
200505
707
737
742
502*
509*
724*
999*
525
535
544
807
818
842
856
210 119
123
605
615
109*
189*
138*
999*
320
220742
747
505*
604*
605*
737*
602*
999*
630
818
849
230 729
742
604*
707*
722*
726*
737*
747*
612*
999*
760
776
VAHR5880
VAHR6712
WVHR1393
XXHROOOO
WVDY3215
VADY0720
VADY5096
VADY8062
WVHR4763
VAHR2208
VAHR8046
VAHR8396
WVHR1323
WVHR6163
VAHR5880
XXHROOOO
WVDY3215
WVDY6960
WVDY9281
VADY5096
VADY5851
VADY8448
VADY9186
PAHR2537
PAHR2838
MDHR1530
MDHR9030
PAHR1354
PAHR9938
PAHR4778
XXHROOOO
PADY8379
VAHR8396
VAHR8906
WVHR4763
MDHR0700
MDHR1530
VAHR8046
MDHR0465
XXHROOOO
MDHR1995
VADY5851
VADY8903
VAHR6712
VAHR8396
MDHR0700
VAHR2208
VAHR5690
VAHR6178
VAHR8046
VAHR8906
MDHR6915
XXHROOOO
VADY0720
VADY2009
0.0001
0.0001
0.0001
0.0001
0.0117
0.1195
0.1350
0.3475
0.0752
0.0979
.0.3060
0.0557
0.0001
0.0001
0.0001
0.0001
0.0089
0.0073
0.0545
0.1108
0.1867
0 (0.2343)
0.0966
0.3897
0.0084
0.2442
0.3199
0.0001
0.0001
0.0001
0.0001
0.0374
0.2044
0.0491
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0279
0.2685
0.4495
0.3089
0.2033
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.2531
0.0325
08:00
08:00
08:00
08:00
08:00
08:00
08:00
08:00
08:00
18:00
08:00
08:00
09:00
08:00
24:00
08:00
09:00
Station Observation
Weight Time
(if daily)
265
270
280
700
710
792 VADY3466 0.0176 07:00
807 VADY5096 0.1838 -08:00
265 713
714
724
503*
513*
707*
722*
735*
999*
813
817
270506
513
707
713
714
720
722
724
735
999*
525
778
798
813
817
836
843
280707
720
722
726
729
724*
735*
999*
756
760
765
782
792
806
843
700108
142
179
181
710 137
138
189
103*
119*
VAHR3310
VAHR4128
VAHR5880
WVHR1393
WVHR9011
VAHR2208
VAHR5690
VAHR7285
XXHROOOO
VADY5595
VADY5756
WVHR5284
WVHR9011
VAHR2208
VAHR3310
VAHR4128
VAHR5120
VAHR5690
VAHR5880
VAHR7285
XXHROOOO
WVDY3215
VADY2044
VADY4565
VADY5595
VADY5756
VADY8062
VADY8600
VAHR2208
VAHR5120
VAHR5690
VAHR6178
VAHR6712
VAHR5880
VAHR7285
XXHROOOO
VADY0243
VADY0720
VADY1136
VAOY2160
VADY3466
VADY5050
VADY8600
PAHR1212
PAHR5731
PAHR8868
PAHR8905
PAHR4763
PAHR4778
PAHR9938
PAHR0605
PAHR2537
0.0960
0.0767
0.2540
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.2625
0.3102
0.0155
0.0599
0.0002
0.0259
0.0000
0.0371
0.0633
0.1082
0.1354
0.0001
0.0001
0.2057
0.2809
0.0159
0.0001
0.0427
0.0090
0.0071
0.1053
0.0870
0.000(-0.25)
0.0005
0.0001,
0.0001
0.0001
0.0717
0.0336
0.1953
0.1247
0.1363
0.0375
0.2007
0.3213
0.4548
0.0089
0.2150
0.1089
0.1552
0.2671
0.0001
0.0001
07:00
07:00
08:00
17:00
07:00
07:00
07:00
08:00
06:00
\
07:00
08:00
07:00
07:00
07:00
18:00
06:00
20
-------
Table D.3.1
Precip Model DSN Station
Segment Segment Name
Station Observation
Weight Time
(if daily)
720
730
740
750
760
123*
129*
149*
615*
999*
253
269
345
720 129
137
138
119*
177*
189*
149*
999*
253
269
305
730 104
109
123
154
105*
119*
161*
605*
999*
281
643.
740 122
502
505
608
737
123*
127*
508*
509*
999*
281
312
643
856
750 119
123
605
760 119
615
123*
189*
604*
605*
601*
602*
PAHR2838
PAHR3321
PAHR6004
MDHR9030
XXHROOOO
PADY4019
PADY4896
PADY9950
PAHR3321
PAHR4763
PAHR4778
PAHR2537
PAHR8763
PAHR9938
PAHR6004
XXHROOOO
RADY4019
PADY4896
PADY7322
PAHR0725
PAHR1354
PAHR2838
PAHR6852
PAHR0763
PAHR2537
PAHR7312
MDHR1530
XXHROOOO
PADY5662
MDDY3975
PAHR2721
WVHR1323
WVHR4763
MDHR4030
VAHR8046
PAHR2838
PAHR3295
WVHR5739
WVHR6163
XXHROOOO
PADY5662
PADY7846
MDDY3975
VADY9186
PAHR2537
PAHR2838
MOHR1530
PAHR2537
MDHR9030
PAHR2838
PAHR9938
MDHR0700
MDHR1530
MDHR0015
MDHR0465
0.0001
0.0001
0.0001
0.0001
0.0001
0.0852
0.2141
0.1688
0.1116
0.1894
0.4663
.0.0001
0.0001
0.0001
0.0001
0.0001
0.0133
0.0823
0.1366
0.0234
0.6995
0.1386
0.0609
0.0001
0.0001
0.0001
0.0001
0.0001
0.0000
0.0771
0.0234
0.1730
0.2085
0.2063
0.0221
0.0001
0.0001
0.0001
0.0001
0.0001
0.0000
0.0002
0.1245
0.2414
0.6449
0.3549
0.0002
0.0010
0.5421
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
07:00
15:00
08:00
07:00
15:00
07:00
08:00
18:00
08:00
07:00
18:00
08:00
Precip Model DSN Station Station Observation
Segment Segment Name Weight Time
Of daily)
1001
1002
1003
1004
1005
138*
999*
320
620
629
420401
430612
440725
745
749
999*
822
400401
820601
390602
830612
770602*
780 749*
604*
747*
129*
999*
840409
410642
370601
380602
800 129*
810 137*
138*
401*
745*
' 999*
409
140 129
450 137
850189
601
602
119*
138*
605*
747*
999*
253
320 '
409
631
510 189
870601
470602
480604
860615
490 119*
612*
747*
PAHR4778
XXHROOOO
PADY8379
MDHR0470
MDHR1862
DEHR3570
MDHR6915
VAHR6139
VAHR8849
VAHR9151
XXHROOOO
VADY6475
DEHR3570
MDHR0015
MDHR0465
MDHR6915
MDHR0465
VAHR9151
MDHR0700
VAHR8906
PAHR3321
XXHROOOO
DEDY6410
MDDY3675
MDHR0015
MDHR0465
PAHR3321
PAHR4763
PAHR4778
DEHR3570
VAHR8849
XXHROOOO
DEDY6410
PAHR3321
PAHR4763
PAHR9938
MDHR0015
MDHR0465
PAHR2537
PAHR4778
MDHR1530
.VAHR8906
XXHROOOO
PADY4019
PADY8379
DEDY6410
MDDY2060
PAHR9938
MDHR0015
MDHR0465
MDHR0700
MDHR9030
PAHR2537
MDHR6915
VAHR8906
0.0001
0.0001
0.0442
0.0150
0.3969
0.2589
0.0284
0.0064
0.5244
0.0001
0.0001
0.1817
0.6525
0.0502
0.0648
0.2110
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0002
0.0207
0.6506
0.1150
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.2338
, 0.0357
0.0243
0.0439
0.1725
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.2493
0.0026
0.1214
0.3497
0.0004
0.0525
0.2394
0.0085
0.0032
0.0001
0.0001
0.0001
08:00
24:00
17:00
16:00
'
17:00
16:00
17:00
07:00
08:00
17:00.
24:00
21
-------
Table D.3.1
Precip
Segment Segment
1006
1007
1008
1009
jl DSN
nent
999*
253
320
631
620
629
642
880612
500747*
910602*
920604*
990 749*
729*
999*
642
776
550604
890612
900742
970 747
602*
615*
729*
999*
624
630
642
776
849
980 612
580734
930749
604*
729*
747*
745*
724*
999*
757
776
B22
600725
610734
590 749
940 612*
747*
745*
999*
757
776
Station
Name
XXHROOOO
PADY4019
PADY8379
MDDY2060
MDDY0470
MDDY1862
MDDY3675
MDHR6915
VAHR8906
MDHR0465
MDHR0700
VAHR9151
VAHR6712
XXHROOOO
MDDY3675
VADY2009
MDHR0700
MOHR6915
VAHR8396
- VAHR8906
MDHR0465
MDHR9030
VAHR6712
XXHROOOO
MDDY1125
MDDY1995
MDDY3675
VADY2009
VADY8903
MDHR6915
VAHR7201
VAHR9151
MDHR0700
VAHR6712
VAHR8906
VAHR8849
VAHR6139
XXHROOOO
VADY0327
VADY2009
VADY6475
VAHR6139
VAHR7201
VAHR9151
MDHR6915
VAHR8906
VAHR8849
XXHROOOO
VADY0327
VADY2009
Station
Weight
0.0001
0.0239
0.1541
0.0001
0.4498
0.0371
0.0306
0.3610
0.3048
0.0001
0.0001
0.0001
0.0001
0.0001
0.2497
0.0840
0.0500
0.0001
.0.1325
0.3211
0.0001
0.0001
0.0001
0.0001
0.0000
0.1193
0.0111
0.0105
0.3550
0.3363
0.0050
0.0873
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0326
0.4957
0.0425
0.0297
0.3208
0.3773
0.0001
0.0001
0.0001
0.0001
0.1246
0.0013
Observation
Time
(if daily)
07:00
08:00
24:00
24:00
17:00
16:00
16:00
09:00
24:00
- 09:00
16:00
09:00
24:00
18:00
09:00
16:00
18:00
09:00
Precip Model DSN Station Station Observation
Segment Segment Name Weight Time
(if daily)
1010
1011
1012
1013
780
822
830
845
857
950 725
630749
960 612*
620 734*
999*
845
330604
340615
119*
602*
605*
734*
742*
747*
999*
624
629
642
729
235 726*
250734*
260 742*
747*
612*
999*
757
776
780
792
806
734
290 720*
300 729*
310749*
722*
999*
755
756
767
757
765
780
782
786
830
857
VADY2142
VADY6475
VADY6906
VADY8800
VADY9213
VAHR6139
VAHR9151
MDHR6915
VAHR7201
XXHROOOO
VADY8800
MDHR0700
MDHR9030
PAHR2537
MDHR0465
MDHR1530
VAHR7201
VAHR8396
VAHR8906
XXHROOOO
MDDY1125
MDDY1862
MDDY3675
VAHR6712
VAHR6178
VAHR7201
VAHR8396
VAHR8906
MDHR6915
XXHROOOO
VADY0327
VADY2009
VADY2142
VADY3466
VADY5050
VAHR7201
VAHR5120
VAHR6712
VAHR9151
VAHR5690
XXHROOOO
VADY0187
VADY0243
VADY1322
VADY0327
VADY1136
VADY2142
VADY2160
VADY2941
VADY6906
VADY9213
0.0018
0.0016
0.0062
0.0454
0.0909
0.7701
0.0679
0.0001
0.0001
0.0001
0.1617
0.2692
0.0532
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0000
0.4485
0.2284
0.0827
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.2494
0.2487
0.0609
0.0652
0.2925
0.0012
0.0001
0.0001
0.0001
0.0001
0.0001
0.1788
0.0663
0.0513
0.0001
0.0001
0.1637
0.0820
0.2324
0.1191
0.1045
08:00
16:00
07:00
07:00
07:00
7:00
24:00
17:00
16:00
18:00
09:00
08:00
07:00
18:00
07:00
07:00
08:00
18:00
07:00
08:00
07:00
07:00
07:00
07:00
('indicates stations which possess Thiessen polygons outside of the segment, but are used to minimize skipped hourly precipitation events)
("indicates time of day that precipitfon data was observed at those stations subject to daily inspection)
22
-------
Table D3.2
Format of Input Files for PRECIP.exe Program
Line FORTRAN
Format
1 714
2 A64
3 14
4 2014
614
1014
7+ 10F8.2
Variable
Name
NGAGES
IDAILY
IHRLY
TYPE
COMP
DIS
AVG
WDNAME
DSN(21)
DSN(1-NGAGES)
SDATE(l-S)
EDATE(l-3)
lOBST(ll-IDAYT)
WGT(l-NGAGES)
Definition
Total number of hourly and daily
stations
Number of daily stations
Number of hourly stations
Set to 2, for Thiessen method
Set to 1
Set to 0
Set to 1
WDM file name and extension
WDM data set number for the
output time series generated by
PRECIP.exe
WDM data set numbers of the
input hourly and daily
precipitation tune series. Enter
hourly stations DSNs first, then
daily station DSNs
Start date in year, month, day format
End date in year, month, day format
Observation times of the daily
stations in the same order as they
appear in line 4. If there are no
daily stations to be included omit
this line, do not leave a blank line
Thiessen weights of the observed
precipitation stations in the same
order as line 4. Enter a maximum of ten
values per line, then start a new line
immediately below following the same
format
23
-------
used to distribute that event by employing a proportional distribution pattern on an hourly basis.
A data gap occurs when daily precipitation stations have precipitation recorded, but the hourly
stations either have zero or missing precipitation. As no hourly distribution is available, for these
instances the precipitation hourly record will contain data gaps.
To eliminate hourly data gaps an ideal hourly station that rained every hour of every day
for the period of the record. This ideal station (DSN999) had an extremely low precipitation
volume (0.00042 inches per hour, or 0.01 inches per day) and was set to a weight of 0.0001 which
was a negligable weight assigned to other nearby hourly stations not in the Thiessen precipitation
segment but close by and used for hourly weights of the precipitation volume. The ideal station had
no impact on a segment's calculated precipitation volume, but was selected when no other hourly
station had precipitation registered for that day. This ideal station was included for all precipitation
segments that missed more than one inch of calculated precipitation over the 1991-1994 run time.
For those stations with less than one inch missed, all events were reviewed and determined to be
less than 0.20 inch in depth. Table D.3.1 is the final draft with Thiessen weights with the
augmented hourly stations marked with an asterisk and the inclusion of the ideal hourly station
identified by an asterisk and a "999" in the DSN column.
Both 1991 data from the above development and from the earlier 1984-1991 dataset were
compared to verify the consistency between them. Table D.3.3 lists the monthly precipitation hi
1991 forthe 1984-1991 data set and for verification with the 1991-1995dataset, and in 1992-1995.
\
In comparing 1991 precipitation of stage 1 and stage 2, there are only minor (<1%)
differences between them. The differences may be due to any of the following reasons: 1)1984-91
used one decimal place for daily precipitation, while 1991-1995 used two decimal places, and 2)
1991-95 used eight fewer precipitation stations than 1984-91 did.
From the above analysis, the 1991-95 precipitation data development was shown to be in
agreement with 1984-91 precipitation data.
Finally, the 1992-95 precipitation data were combined with 1984-1991 data using
ANNIE.exe software, yielding 1984-95 precipitation data for application in the Phase IV
Chesapeake Bay Watershed Model.
24
-------
Table D.3.3
Summary of 1991 Precipitation Data from Stage 1 WDM Files
DATE
DSN 1010
DSN 1020
DSN 1030
DSN 1040
DSN 1050
DSN 1060
DSN 1070
DSN 1080
DSN 1090
DSN 1100
DSN 1110
DSN 1120
DSN 1160
DSN 1170
DSN 1175
DSN 1180
DSN 1190
DSN 1200
DSN 1210
DSN 1220
DSN 1230
DSN 1265
DSN 1270
DSN 1280
DSN 1700
DSN 1710
DSN 1720
DSN 1730
DSN 1740
DSN 1750
DSN 1760
DSN 2001
DSN 2002
DSN 2003
DSN 2004
DSN 2005
DSN 2006
DSN 2007
DSN 2008
DSN 2009
DSN 2010
DSN 2011
DSN 2012
DSN 2013
Jan-91
1.67
2.22
1.87
2.59
3.10
1.97
2.20
2.39
1.97
1.90
2.59
3.01
2.63
3.02
2.66
2.94
3.09
3.12
3.20
3.01
3.64
4.07
3.76
3.67
1.28'
2.46
2.79
2£4
2.81
3.00
3.38
4.59
4.55
3.68
3.50
3.26
3.31
2.98
3.62
3.90
4.55
3.24
3.71
4.17
Feb-91
1.24
1.79
1.58
1.68
1.82
1.43
1.79
1.62
1.66
1.66
1.12
1.13
1.72
0.96
1.20
1.09
1.45
1.01
1.34
0.82
1.04
1.74
2.00
1.94
1.27
1.15
1.16
1.44
1.11
1.50
1.15
0.87
0.86
1.08
1.19
0.78
0.80
0.80
0.96
1.19
0.88
0.94
1.08
2^2
Mar-91
2.96
3.63
3.33
3.64
5.20
4.15
3.59
3.97
4.12 •
4.62
3.61
3.52
4.01
5.06
4.43
4.25
5.20
4.70
4.04
4.94
5.01
6.04
6.81
5.56
2.99
3.55
3.74
4.31
4.17
4.12
4.03
. 4.89
5.56
4.92
4.34
4.89
4.71
4.92
4.48
'5.40
4.63
5.34
4.11
5.44
Apr-91
2.97
4.44.
3.11
2.91
3.52
2.89
2.72
2.48
2.67
2.70
2.00
2.25
3.04
2.03
1.93
2.11
1.88
1.93
2.02
1.80
2.48
2.14
2.25
2.42
2.99
1.85
2.28
2.87
2.04
2.36
1.73
2.96
2.64
2.66
2.34
1.91
1.66
1.67 '
1.60
1.67
5.41
1.92
1.59
1.39
' May-91 .
1.05
2.54
2.34
2.57
1.95
1.83
2.16
2.03
1.46
1.45
2.82
1.64
2.12
2.15
1.81
1.95
1.69
1.63
1.85
1.30
1.71
2.16
2.91
2.36
0.98
2.36
2.50
2.79
1.88
2.50
1.92
0.72 .
1.23
2.14
2,17
1.34
1.62
1.64
1.49
0.98
0.67
2.02
1.36
1.93
Jun-91
0.92
1.55
1.13
2.34
2.64
1.51
1.37
0.84
1.28
1.37
0.66
1.65
1.48
1.22
Z25
1.27
3.56
2.48
0.90
3.98
3.47
2.33
2.65
3.22.
0.67
0.81
1.92
0.58
1.61
0.50
1.43
2.62
3.22
1.34
1.73
0.80
2.45
3.46
3.39
4.82
4.22
1.95
3.72
2.88
Jul-91
2.53
3.12
2.84
3.31
3.33
2.80
3.23
2.06
2.61
2.37
1.92
3.24
2.69
4.02
2.43 .
1.93
7.31
2.74
2.08
2.65
5.30
5.74
6.00
8.24
2.05
1.90
3.06
2.03
1.63
2.32
1.67
3.89
4.34
3.18
3.19
2.47
3.58
3.66
4.12
5.91
7.15
2.25
' 7.61
6.30
Aug-91
2.61
3.72
2.29
4.48
1.78
2.76
3.6
4.58
2.47
2.93
3.77
2.40
2.32
2.35
2.32
2.23
2.26
1.71
5.54
1.07
1.43
2.89
2.13
2.51
1.63
3.39
3.41
2.75
2.21
4.61
4.63
5.48
4.10
3.39
3.21
2.53
2.08
1.69
1.17
2.86
4.10
3.21
1.20
4.13
Sep-91
2.45
3.09
"> 3.15
3.63
3.00
3.29
4.18
2.32
1.49
2.32
3.65"
4.43
1.19
1.31
0.94
1.78
0.80
1.33
4.29
2.56
1.67
0.60
0.77
1.29
2.40
3.67
3.53
1.46
1.79
2.10
3.85
2£9
4.09
4.42
4.25
3.68
3.11
2.98
3.01
2.74
2.27
3.42
2.47
2.83
Oct-91
1.81
1.85
2.14
2.71
1.31
1.69
2.26
2.09
1.16
1.42
2.96
2.48
1.09
0.5
0.91
2.62
0.99
1.47
2.17
1.71
1.73
1.11
0.63
1.13
1.37
2.8
2.78
2.81
1.55
2.69
1.87
3.62
3.04
1.83
1.93
2.55
2.77
1.94
2.74
2.92
4.26
2.59
1.83
1.87
Nov-91
2.86
3.91
3.52
3.49
2.49
2.86
3.12
2.95
2.73
2.76
2.27
2.22
2.68
2.22
2.48
1.92
2.43
2.13
2.11
2.32
2.71
3.38
3.42
2.67
3.47
2.04
1.96
2.44
2.3
2.25
2.36
0.86
0.98
2.18
2.18
2.02
1.11
1.86>
1.15
0.85
1.46
2.16
1.42
1.23
Dec-91
2.76
2.8
2.81
3.19
2.83
3.01
3.18
2.93
3.06
2.62
3.41
3.7
3.97
3.88
3.64
4.1
4.46
4.29
3.86
4.6
4.73
5.63
4.79
5.36
2.47
3.44
3.35
3.42
3.72
3.73
4.23
3.54
4.37
4.21
A 4
•». 1
4.38
5.28
4.89
5.82
3.93
2.5
4.73
5.36
4.68
25
-------
Table D.3.3
Summary of 1991 Precipitation Processed by Stage 2 for Verification with Stage 1
DSN 1010
DSN1020
DSN 1030
DSN 1040
DSN 1050
DSN 1060
DSN 1070
DSN 1080
DSN 1090
DSN 1100
DSN 1110
DSN 1120
DSN 1160
DSN 1170
DSN 1175
DSN 1180
DSN 1190
DSN 1200
DSN 1210
DSN 1220
DSN 1230
DSN 1265
DSN 1270
DSN 1280
DSN 1700
DSN 1710
DSN 1720
DSN 1730
DSN 1740
DSN 1750
DSN 1760
DSN 2001
DSN 2002
DSN 2003
DSN 2004
DSN 2005
DSN 2006
DSN 2007
DSN 2008
DSN 2009
DSN 2010
DSN 2011
DSN 2012
DSN 2013
Jan-91
1.68
2.22
1.87
2.54
3.10
2.00
2.22
2.41
2.01
1.97
2.63
2.90
3.27
2.81
2.75
3.61
3.48
3.25
3.21
2.89
3.57
3.46
3.75
3.51
1.28
2.45
2.73
2.69
2.84
3.00
3.32
4.60
4.55
3.68
3.34
3.25
3.32
2.95
3.59
3.90
4.56
3.18
3.63
4.19
Feb-91
1.26
1.79
1.59
1.74
1.59
1.54
1.79
1.60
1.68
1.63
1.14
1.23
1.65
0.96
1.16
1.18
1.47
1.02
1.45
0.85
1.00
1.75
2.01
2.04
1.27
1.16
1.27
1.45
1.11
1.50
1.11
0.88
0.86
1.08
1.19
0.84
0.83
0.84
0.96
1.16
0.84
1.01
1.05
2.23
Mar-91
2.96
3.63
3.31
3.53
5.20
4.11
3.56
3.97
4.08
4.58
3.61
3.45
4.10
5.12
4.45
4.21
5.17
4.78
4.04
5.02
. 5.01
5.64
6.75
5.61
2.99
3.54
3.77
4.32
4.17
4.12
4.12
4.87
5.56
4.94
4.36
4.92
4.75
4.98
4.47
5.82
6.08
5.46
4.09
5.44
Apr-91
2.97
4.44
3.11
2.84
3.08
2.88
2.70
2.49
2.67
2.66
1.96
2.60
3.06
2.06
1.98
2.22
1.92
1.93
2.02
1.76
2.46
2.02
2.19
2.33
2.99
1.84
• 2.40
2.93
2.01
2.36
1.69
2.98
2.64
2.64
2.42
1.86
1.70
1.63
1.76
1.71 .
5.42
1.88
1.70
1.32
C
May-91
1.05
2.54
2.33
2.57
1.95
1.87
2.14
2.01
1.45
1.49
2.83
1.79
2.11
2.13
.84
.41
.76
.55
.85
1.33
1.73
2.12
2.94
2.50
0.98
2.49'
2.93
2.75
1.83
2.50
1.86
0.73
1.23
2.15
2.26
1.35
1.61
1.64
1.56
0.98
0.66
1.98
1.40
1.96
(ATE
Jun-91
0.92
1.55
1.12
2.31
2.32
1.53
1.40
0.96
1.32
1.39
0.65
1.67
1.45
1.18
2.35
1.22
3.53
2.49
0.90
4.02
3.49
2.16
2.65
3.43
0.67
0.68
2.11
0.60
1.72
0.50
1.36
2.64
3.22
1.34
1.72
0.84
2.45
3.49
3.43
4.85
4.50
1.86
3.76
2.86
Jul-91
2.52
3.12
2.85
3.39
3.33
2.80
3.20
2.04
2.58
2.42
1.83
3.78
2.69
4.06
2.38
1.87
7.30
2.80
2.07
2.57
5.34
5.89
6.15
7.12
2.05
1.80
3.24
2.03
1.62
2.32
1.66
3.90
4.37
3.17
3.22
2.36
3.59
3.61
4.18
5.92
7.06
2.30
7.69
6.23
Aug-91
2.61
3.72
2.30
4.48
1.71
2.79
3.62
4.59"
2.44
2.85
3.81
2. 1O
2.34
2.36
2.33
2.03
2.24
1.69
5.55
1.04
1.43
2.72
2.14
2.62
1.63
3.50
3.69
2.79
2.19
4.61
4.62
5.46
4.10
3.35
3.24
2.46
2.09
1.70
0.96
2.87
.4.08
3.25
1.23
4.18
Sep-91
2.46
3.09
3.16
3.67
3.24
3.34
4.23
2.30
1.47
2.19
3.70
4.53
1.14
1.33
1.02
—
0.77
1.14
—
2.61
•1.61
0.63
0.79
1.51
2.40
3.66
3.44
—
—
—
3.93
2.89
4.09
4.38
4.16
3.72
3.12
3.04
3.20
2.73
2.26
3.48
2.46
2.84
Oct-91
1.81
1.85
2.14
2.71
1.32
1.74
2.26
2.12
1.14
1.38
2.96
2.15
1.08
0.55
0.97
2.07
1.06
1.32
2.17
1.75
1.76
1.10
0.63
0.96
1.37
2.78
2.81
2.77
1.64
2.69
1.91
3.63
3.04
1.80
1.92
2.57
2.77
1.99
2.76
2.95
4.25
2.62
1.88
1.87
Nov-91
2.86
3.91
3.51
3.39
2.59
2.87
3.18
3.01
2.82
2.80
2.33
2.28
2.69
2.92
2.46
1.69
2.51
2.00
2.11
2.40
2.75
3.36
3.49
2.61
3.47
Z11
2.06
2.43
1.20
2.25
2.34
0.86
0.98
2.08
2.10
2.01
1.14
1.90
1.14
0.88
1.45
2.15
1.39
1.15
Dec-91
2.76
2.8
2.81
3.21
2.94
3.04
3.22
2.93
2.98
2.57
3.57
3.63
4.00
'3.88
3.69
3.02
4.43
4.35
3.86
4.53
4.67
5.59
4°82
5.53
2.47
3.53
. 3.14
3.26
3.66
3.73
4.35
3.56
4.37
4.18
4.09
4.36
5.31
4.84
5.76
3.89
2.49
4.88
5.44
4.70
Note: There are no values for segments 1180,1210,1730,1740, and 1750 due to unacceptable raw data for those segments.
26
-------
Table D.3.3
Summary of 1992 Precipitation Data Processed by Stage 2
DSN 1010
DSN 1020
DSN 1030
DSN 1040
DSN 1050
DSN 1060
DSN 1070
DSN 1080
DSN 1090
DSN 1100
DSN 1110
DSN 1120
DSN 1160
DSN 1170
DSN 1175
DSN 1180
DSN 1190
DSN 1200
DSN 1210
DSN 1220
DSN 1230
DSN 1265
DSN 1270
DSN 1280
DSN 1700
DSN 1710
DSN 1720
DSN 1730
DSN 1740
DSN 1750
DSN 1760
DSN 2001
DSN 2002
DSN 2003
DSN 2004
DSN 2005
DSN 2006
DSN 2007
DSN 2008
DSN 2009
DSN 2010
DSN 2011
DSN 201 2
DSN 201 3
Jan-92
1.73
1.70
1.69
1.34
1.84
1.93
1.76
1.62
1.87
1.53
1.37
1.87
1.79
1.35
1.36
1.47
2.57
2.26
1.52
2.38
3.03
1.49
2.28
2.80
.69
.50
.56
.66
.38
.65
2.04
1.57
1.06
1.14
1.57
1.43
1.92
2.38
2.17
2.41
4.37
2.06
2.03
2.37
Feb-92
1.21
2.07
1.70
2.00
1.76
1.42
1.66
1.90
1.96
1.64
1.58
1.47
2.88
1.49
1.82
1.29
2.05
1.77
1.84
2.07
2.19
4.01
2.82
2.99
1.36
1.55
1.45
1.99
' 1.95
1.98
2.50
2.76
3.12
2.57
1.26
2.35
2.72
2.25
2.95
2.75
2.09
2.58
2.8
3.03
Mar-92
3.24
3.30
3.52
4.97
3.22
3.59
4.74
4.73
3.96
3.79
4.54
3.90
4.07
2.76
3.08
3.86
3.01
3.11
5.09
3.49
3.05
4.04
3.48
3.20
, 3.59
4.26
3.83
5.13
3.63
5.49
4.29
3.42
3.59
4.67
4.26
4.38
4.50
3.50
4.42
4.88
2.72
4.27
4.22
4.02
Apr-92
2,88
3.17
2.53
2.68
2.45
2.58
2.30
2,64
1.91
2.02
2.3B
1.70
2.33
2.52
2.35
4.09
4.44
4.01
, 3.53
3.73
4.23
3.46
4.39
3.34
2.40
1.97
1.48
3.26
• 3.52
3.18
2.76
1.56
1.36
1.67
0.98
1.98
2.19
2.78
1.77
2.44
1.70
2.62
2.04
2.72
C
May-92
2.56
4.68
4.11
2.45
2.63
2.72
3.44
3.09
2.59
2.77
3.97
4.18
3.28
3.49
3.60
3.93
4.16
3.79
3.29
4.09
4.49
4.61
4.43
4.84
3.54
3.99
4.36
4.14
4.15
4.08
3.45
4.15
3.57
4.30
4.10
3.19
3.54
3.91
3.96
4.55
3.78
4.04
3.94
4.87
IATE
Jun-92
2.03
1.73
1.64
2.82
1.58
2.22
2.82
£15
1.99
1.83
2.30
2.60
2.12
2.01
. 2.78
3.21
3.27
3.10
3.32
2.81
4.09
4.61
4.60
3.62
1.52
2.01
2.94
2.75
3.65
2.81
1.77
2.78
3.50
3.51
1.64
2.29
2.67
2.48
2.48
2.86
2.36
1.72
2.47
2.90
Jul-92
7.34
6.17
5.27
5.32
6.98
8.09
7.97
4.87
5.28
4.02
4.67
2.74
7.43
3.09
5.14
4.81
4.19
4.70
6.55
6.78
4.80
3.94
3.12
3.35
6.02
4.21
4.01
4.11
4.41
5.69
5.81
4.81
8.24
5.94
3.47
4.61
7.14
6.79
6.15
5.76
4.77
7.55
3.48
3.34
Aug-92
3.32
2.71
2.83
2.97
4.92
3.98
2.64
2.48
2.77
1.82
1.88
2.15
2.B3
1.65
2.56
2.55
2.00
2.08
2.51
1.68
2.60
2.22
2.27
2.05
3.54
1.81
2.36
2.08
2.32
1.60
2.14
5.16
4.85
2.95
2.33
2.48
4.14
2.03
5.76
7.49
12.97
2.41
4.03
3.86
Sep-92
3.87
3.43
3.30
3.02
4.34
4.09
2.60
3.00
3.10
3.21
4.75
3.78
1.75
1.96
2.60
4.96
4.38
4.83
4.81
5.39
6.03
2.18
2.95
5.46,
2.78
4.44
4.17
4.24
3.82
4.69
'4.19
5.59
5.20
5.62
2.42
5.45
4.17
4.81
3.87
2.29
2.31
4.45
4.15
3.12
Oct-92
2.17
3.34
2.52
2.15
1.45
1.77
1.20
1.75
0.68
0.85
1.58
2.50
0.59
0.29
0.47
0.65
1.57
0.75
1.32
2.11
1.97
1.06
1.54
1.87
2.72
1.50
1.82
0.68
0.41
1.26
1.98
1.45
1.65
1.86
2.14
2,18
1.82
2.04
1.93
2.37
2.82
2.17
2.09
2.25
Nov-92
3.13
4.06
3.75
3.52
4.14
4.30
3.65
4.31
3.66
4.03
4.96
3.57
3.28
1.65
3.03
3.74
4.06
3.42
4.78
5.26
5.82
4.81
4.54
5.60
3.07
4.31
4.11
5.28
2.20
6.18
5.22
4.65
2.77
4.04
2.24
4.20
3.28
4.30
3.09
3.03
4.00
4.88
4.09
3.69
Dec-92
2.74
2.6
3.18
2.17
3.39
3.29
1.94
3.57
4.21
4.09
2.87
3.79
4.59
2.56
4.25
4.49
5.68
5.81
3.81
4.73
7.69
3.00
2.85
4.60
3.06
2.87
3.75
5.63
4.65
4.30
4.87
4.46
4.61
4.85
3.73
4.11
4.08
3.88
4.40
3.53
3.44
4.53
4.83
3.94
27
-------
Table D.3.3
Summary of 1993 Precipitation Data Processed by Stage 2
DATE
DSN 1010
DSN 1020
DSN 1030
DSN 1040
DSN 1050
DSN 1060
DSN 1070
DSN 1080
DSN 1090
DSN 1100
DSN 1110
DSN 1120
DSN 1160
DSN 1170
DSN 1175
OSN 1180
DSN 1190
DSN 1200
DSN 1210
DSN 1220
DSN 1230
DSN 1265
DSN 1270
DSN 1280
DSN 1700
DSN 1710
DSN 1720
DSN 1730
DSN 1740
DSN 1750
DSN 1760
DSN 2001
DSN 2002
DSN 2003
DSN 2004
DSN 2005
DSN 2006
DSN 2007
DSN 2008
DSN 2009
DSN 2010
DSN 2011
DSN 201 2
DSN 201 3
Jan-93
1.78
2L39
1.80
1.85
2.95
2.48
1.53
2.24
1.75
1.88
1.94
1.77
1.81
1.32
1.41
1.73
2.39
1.81
2.08
2.50
2.88
1.94
2.70
4.38
1.41
1.76
1.97
2.08
1.67
2^7
2.41
3.62
3.21
2.80
2.02
2.55
3.27
2.84
3.65
4.66
4.93
2.86
3.99
4.81
Feb-93
.28
.77
.45
.37
2.10
.75
.14
.66
2.08
1.90
2.40
2.40
2.42
1.52
1.83
2.14
2.29
1.84
3.26
2.44
2.56
2.18
3,00
3.45
1.13
2.08
2.39
2.76
1.67
3.20
2.54
1.64
2.84
3.11
1.44
2.75
2.53
2.46
2.72
2.48
2.23
2.30
2.83
, 3.24
Mar-93
3.81
3.98
4.36
3.63
4.77
5.18
3.9
6.25
5.93
5.31
6.10
6.63
7.16
6.62
6.94
5.57
7.38
7.85
7.81
7.67
7.75
5.69
7.49
8.25
3.61
5.60
5.97
6.99
6.73
7.77
1.28
5.87
7.81
7.57
7.17
7.92
7.38
7.53
8.08
6.86
6.23
4.24
8.08
7.90
Apr-93
6.72
6.95
7.59
7.49
6.98
7.45
6.17
6.89
8.77
7.81
6.90
6.08
6.59
3.60
6.26
4.91
4.34
4.08
6.07
3.76
4.98
3.69
3.67
4.57
7.43
6.54
6.62
8.06
5.81
6.97
6.32
2.88
2.99
4.85
3.24
4.39
3.43
4.64
4.20
3.75
3.57
. 4.95
4.74
6.20
May-93
. 1.47
1.63
1.58
1.61
2.47
1.86
1.65
2.31
2.39
2.09
2.45
1.75
2.23
1.30
1.48
2.21
2.84
1.56
2.24
2.58
3.46
4.20
3.02
4.92
1.61
1.85
1.68
2.25
1.20
2.08
2.49
4.22
3.60
3.94
2.44
2.87
3.86
3.21
4.48
5.02
3.57
3.51
4.75
5.15
Jun-93 ,.
2.36
3.52
2.82
2.42
2.69
3.23
2.62
2.44
2.74
2.43
2.96
1.70
2.74
2.33
2.65
2.16
2.02
3.04
2.15
3.12
2.69
2.00
3.27
2.15
3.65
2.74
2.27
2.59
2.73
2.65
3.37
1.71
2.06
2.81
1.10
2.66
1.85
1.96
2.05
2.26
2.70
2.40
1.87
2.07
Jul-93
1.56
1.65
2.09
1.70
3.83
2.88
1.71*
3.41
3.89
3.13
3.44
2.19
3.48
1.78
3.49
2.07
2.65
2.66
2.12
1.68
3.03
2.16
2.47
2.86
1.32
3.09
2.68
3.40
2.75
2.78
1.58
0.44
1.27
2.43
1.86
2.11
1.10
1.56
1.10
1.48
0.36
1.37
1.58
1.93
Aug-93
3.08
3.03
3.71
4.42
2.55
3.93
3.68
4.29
2.57
2.14
4.16
3.33
2.48
2.11
1.88
2.28
2.18
2.25
3.48
3.68
2.71
2.32
2.05
2.32
3.24
3.75
2.48
2.57
1.86
3.44
4.04
3.00
4.73
2.93
3.54
3.60
4.54
4.36
3.44
2.50
1.34
4.84
2.35
2.54
Sep-93
4.42
3.69
5.42
4.56
5.50
5.10
4.21
4.34
4.63
4.27
6.47
6.09
5.04
4.09
4.29
6.97
4.23
4.13
8.84
4.22
3.60
4.98
4.31
3.88
3.76
6.70
7.46
5.57
5.39
7.79
5.16
2.76
2.58
6.09
6.59
4.99
3.24
4.26
4.25
2.78
3.95
4.17
4.14
4.30
Oct-93
2.10
2.84
3.61
2.90
3.03
3.30
2.52
3.32
2.81
2.47
3.47
2.93
2.78
2.08
2.25
1.92
2.32
2.38
2.91
2.41
2.79
2.64
2.11
2.44
2.23
3.35
3.41
3.10
2.49
3.12
2.98
4.02
2.46
3.08
3.86
3.22
2.65
2.51
2.60
2.78
3.45
3.35
2.39
2.75
Nov-93
4.17
3.91
4.13
2.99
5.38
4.86
3.53
3.45
4.90
4.77
4.46 '
3.97
3.46
3.29
4.15
3.21
3.87
4.47
4.61
5.86
5.74
2.87
2.80
5.96
3.50
4.46
4.50
5.11
4.29
4.68
4.72
1.78
3.23
2.94
3.64
3.61
4.89
5.70
4.33
2.98
1.25
5.13
6.57
6.40
Dec-93
1.84
2.97
3.16
2.85
2.78
2.50
2.17
3.23
2.84
2.50
4.30
4.35
3.14
2.37
3.07
3.00
3.71
3.69
4.10
4.12
3.90
4.69
3.82
4.88
2.50
4.42
4.78
3.72
3.89
3.94
4.52
3.51
4.53
4.56
4.70
4.50
4.41
4.31
4.41
3.89
3.38
4.81
4.53
5.56
28
-------
Table D.3.3
Summary of 1994 Precipitation Data Processed by Stage 2
DATE
DSN 1010
DSN 1020
DSN 1030
DSN 1040
DSN 1050
DSN 1060
DSN 1070
DSN 1080
DSN 1090
DSN 1100
DSN 1110
DSN 1120
DSN 1160
DSN 1170
DSN 1175
DSN 1180
DSN 1190
DSN 1200
DSN 1210
DSN 1220
DSN 1230
DSN 1265
DSN 1270
DSN 1280
DSN 1700
DSN 1710
DSN 1720
DSN 1730
DSN 1740
DSN 1750
DSN 1760
DSN 2001
DSN 2002
DSN 2003
DSN 2004
DSN 2005
DSN 2006
DSN 2007
DSN 2008
DSN 2009
DSN 2010
DSN 2011
DSN 2012
DSN 2013
Jan-94
2.57 .
3.59
3.82
4.04
4.03
3.00
3.07
4.73
4.55
4.05
4.10
4.75
4.72
2.28
3.92
2.70
4.55
3.62
3.78
4.12
4.34
4.49
4.17
4.42
3.32
3.44
5.05
4.69
4.03
3.90
3.72
3.35
4.62
4.32
5.33
4.42
4.50
4.28
4.29
3.31
3.89
4.56
3.92
3.32
Feb-94
1.56
1.91
1.45
1.65
2.75
2.11
1.73
2^7
3.44
2.98
3.40
4.14
5.65
3.81
4.30
256
3.65
3.96
3.74
3.80
3.81
4.84
3.78
5.10
1.51
3.36
3.06
3.40
4.14
3.39
4.22
5.13
4.00
2.57
3.52
4.17
4.25
3.88
5.52
4.40
3.64
3.65
5.06
5.40
Mar-94
4.11
5.09
4.46
4.78
6.54
4.93
4.32
6.34
6.37
5.78
5.68
5.51
6.47
4.66
6.03
4.20
7.01
6.65
6.41
6.98
7.61
6.64
6.30
8.73
4.31
5.45
5.52
5.80
6.19
5.56
7.29
9.72
9.78
7.66
6.06
8.24
9.36
7.76
9.69
8.29
10.01
8.69
9.37
9.10
Apr-94
2.67
3.36
4.57
3.18
5.61
3.71
3.23
2.70
2.99
2.66
2.08
2.82
3.91
1.92
2.90
1.75
2.54
2.73
2.16
2.19
3.08
2.69
3:28
2.09
0.00
0.00
3.12
0.37
2.51
0.00
1.81
0.94
3.09
3.01
2.72
2.12
2.51
1.84
2.65
2.44
0.70
2.57
3.45
2.51
May-94
2.47
2.52
2.45
2.03
3.41
2.40
2.25
2.87
3.00
2.66
3.01
3.80
4.34
2.86
3.20
2.16
2.53
3.02
2.75
3.15
2.24
4.12
2.63
2.14
1.81
3.41
4.11
2.86
3.95
2.71
3.25
2.89
3.07
3.40
3.27
2.83
2.12
2.57
1.91
2.96
3.24
2.94
2.33
3.09
Jun-94
5.64
6.30
5.03
4.66
4.61
5.90
4.39
3.51
2.09
1.91
2.21
2.16
3.36
2.00
2.63
1.78
2.83
2.89
4.15
4.06
3.77
2.84
3.20
3.45
7.63
1.96
2.61
1.92
1.56
3.55
2.19
2.82
1.86
0.90
1.68
2.45
2.19
3.71
2.87
1.69
1.36
2.61
2.33
3.79
Jul-94
2.88
4.19
4.34
4.14
3.73
4.42
4.61
4.80
4.50
3.50
6.40
5.69
5.29
4.85
5.40
3.36
4.42
4.70
3.73
5.52
6.82
-6.88
5.53
6.81
5.29
7.34
6.67
3.84
4.45
3.78
4.98
6.90
6.32
9.28
6.46
5.22
5.97
5.12
7.57
7.67
12.46
8.47
7.62
5.52
Aug-94
6.82
6.46
7.16
4.84
8.84
8.29
5.47
6.95
7.58
6.60"
5.31
5.94
5.02
4.28
4.56
4.16
5.20
5.72
4.08
5.34
5.54
3.73
5.64
5^10
6.25
4.93
5.81
7.39
6.28
5.21
4.95
3.23
3.93
3.83
4.04
4.47
5.11
4.92
4.86
3.35
3.62
7.61
5.46
3.71
Sep-94
2.19
2.68
3.96
3.07
3.12
2.89
3.60
2.33
2.12
2.31
2.67
3.12
1.03
0.78
1.26
2.85
1.67
2.54
3.65
3.47
3.51
0.57
1.06
3.11
3.05
2.60
2.78
3.84
2.02
3.84
2.89
3.55
3.09
2.23
2.56
2.98
3.14
3.05
4.02
3.43
2.59
3.10
4.38
3.86
Oct-94
1.63
0.91
1.10
6.66
0.89
0.74
0.59
0.78
0.97
0.72
1.04
1.10
0.79
0.40
0.96
0.79
1.28
0.80
0.91
1.06
1.20
0.97
1.49
1.63
1.27
1.04
1.10
0.80
1.13
0.94
1.08
2.28
. 1.56
0.82
0.93
1.29
1.44
1.14
1.67
2.36
2.52
1.35
1.79
2.16
Nov-94
3.36
3.05
4.26
4.01
4.74
4.36
4.01
3.70
4.04
4.16
5.39
3.16
3.38
2.06
3.63
2.15
2.47
2.93
4.89
2.33
3.01
1.72
1.45
221
2.76
5.14
4.69
5.27
3.68
5.29
4.06
3.90
2.07
2.52
3.26
2.71
2.11
1.91
2.75
3.54
4.95
2.39
2.41
3.45
Dec-94
1.89
2.72
2.54
2.15
3.04
2.70
2.45
2.74
2.91
2.71
2.93
1.81
2.99
1.78
2.88
2.47
2.12
2.54
Z53
2.62
2.51
2.54
2.32
1.66
2.13
2.97
3.06
3.30
3.04
2.64
3.13
1.54
1.49
2.13
228
2.05
1.71
2.42
1.16
0.89
1.22
2.31
1.53
0.80
29
-------
Table D.3.3
Summary of 1995 Precipitation Data Processed by Stage 2
DSN 1010
DSN 1020
DSN 1030
DSN 1040
DSN 1050
DSN 1060
DSN 1070
DSN 1080
DSN 1090
DSN 1100
DSN 1110
DSN 1120
DSN 1160
DSN 1170
DSN 11 75
DSN 1180
DSN 1190
DSN 1200
DSN 1210
DSN 1220
DSN 1230
DSN 1265
DSN 1270
DSN 1280
DSN 1700
DSN 1710
DSN 1720
DSN 1730
DSN 1740
DSN 1750
DSN 1760
DSN 2001
DSN 2002
DSN 2003
DSN 2004
DSN 2005
DSN 2006
DSN 2007
DSN 2008
DSN 2009
DSN 2010
DSN 2011
DSN 2012
DSN 201 3
Jan-95
2.83
2.43
2.97
3.87
2.78
3.47
4.23
4.52
3.16
3.50
4.18
4.13
3.71
4.70
3.45
3.37
6.56
4.06
4.48
3.97
5.28
6.20
7.24
5.60
2.14
4.08
3.61
4.17
3.64
4.54
3.89
2.82
3.08
3.80
4.46
3.41
3.61
3.67
3.94
3.25
2.58
3.87
4.60
4.41
Feb-95
0.95
, 2.50
1.38
1.46
1.96
1.47
1.37
1.74
1.68
1.59
1.81
2.04
1.89
0.66
0.83
0.92
1.19
0.90
1.68
1.51
1.47
1.80
1.78
2.31
0.66
1.87
1.98
1.34
0.62
1.10
1.93
1.82
2.16
2.12
2.29
1.89
1.89
1.71
1.70
1.68
2.67
2.07
1.48
1.77
Mar-95
0.91
1.13
1.03
1.24
1.44
1.17
1.11
1.16
1.34
1.21
1.38
2.41
0.89
1.33
1.33
1.45
1.51
1.31
0.81
1.58
2.28
1.82
1.57
1.70
0.63
1.42
1.94
1.29
1.59
0.98
1.44
1.98
2.26
1.36
2.26
1.67
2.55
1.89
2.81
3.11
3.28
1.90
2.46
2.67
Apr-95
1.76
/ 2.38
2.47
2.40
2.67
2.67
2.36
2.31
2.37
2.45
2.10
1.33
2.35
2.11
1.81
2.29
1.65
1.76
1.00
2.15
1.83
1.88
1.45
1.65
2.33
1.94
1.95
• 1.95
1.92
1.33
1.68
3.86
2.48
2.09
1.83
1.63
2.22
2.07
2.66
2.34
2.94
2.20
2.39
2.29
C
May-95
1.56
1.91
1.93
2.31
4.30
3.48
2.46
2.91
3.36
3.59
4.39
3.40
4.33
4.06
3.55
3.48
4.81
4.13
3.70
4.76
5.31
4.30
4.47
5.83
1.49
3.76
3.29
3.05
4.87
3.47
5.88
4.06
4.22
3.89
3.63
4.08
4.39
4.91
4.23
4.61
2.68
6.15
5.31
5.97
IATE
Jun-95
1.87
1.88
2.00
3.88
5.12
3.23
3.59
5.50
5.02
5.84
3.51
2.42
6.29
6.78
5.84
8.23
10.44
6.68
7.72
5.19
10.60
7.71
11.11
9.56
1.93
3.76
3.21
6.26
6.46
7.10
2.94
2.56
2.73
1.53
3.09
1.88
2.95
3.34
4.02
3.17
4.80
2.48
6.48
4.94
Jul-95
1.79
2.32
3.38
3.83
3.16
2.31
2.50
2.47
2.12
2.10
5.92
3.98
2.71
4.10
2.95
3.32
2.48
2.25
2.84
3.78
3.38
2.54
3.03
4.17
2.53
6.73
5.68
2.97
3.73
3.03
6.05
4.10
6.45
3.02
2.65
4.34
3.57
3.90
5.77
4.00
2.27
3.32
5.26
6.43
Aug-95
3.02
2.55
1.72
0.72
1.73
1.25
0.75
0.83
1.28
1.16
1.29
1.13
3.71
3.23
3.42
4.10
2.00
3.90
1.54
2.78
2.42
1.23
0.94
1.38
3.22
0.77
0.50
0.79
3.70
1.26
3.06
1.59
2.37
1.96
1.45
2.71,
.02
.71
.08
.65
.43
2.02
1.25
0.92
Sep-95
2.08
3.15
2.81
2.04
1.34
1.39
1.57
1.79
1.72
1.70
2.48
3.70
1.77
1.67
1.68
3.15
3.40
2.38
2.95
2.93
3.17
2.37
2.37
3.27
3.22
2.80
2.99
1.75
2.08
2.68
2.79
5.15
3.65
3.81
4.34
.3.20
3.26
3.16
2.99
3.76
4.63
3.38
3.14
3.49
Oct-95
6.41
6.51
6.78
7.87
6.30
7.27
7.42
8.23
6.58
7.18
6.67
7.14
4.46
3.65
5.50
6.54
7.15
6.24
5.09
6.41
7.50
4.15"
4.70
8.29
6.12
6.80
8.27
8.89
7.06
6.50
6.05
4.74
6.61
6.46
6.38
6.27
7.37
7.18
6.89
5.47
4.95
7.44
8.39
7.24
Nov-95
3.09
3.72
4.35
5.15
4.26
4.51
4.57
4.51
3.98
4.14
4.49
4.55
3.34
2.48
3.85
3.79
3.39
3.66
3.72
4.54
4.34
3.05
4.02
4.16
3.02
4.70
5.18
4.87
3.96
3.81
4.88
2.88
3.92
4.62
4.63
4.38
3.79
4.83
3.64
2.75
3.02
4.32
3.67
3.27
Dec-95
1.29
2.14
1.42
1.38
1.77
1.74
1.33
1.92
2.49
2.10
2.56
1.78
2.37
1.81
1.92
2.17
2.33
2.07
1.79
2.06
2.26
2.22
2.15
2.28
1.34
2.39
2.22
2.11
2.23
1.84
1.81
2.22
2.86
2.26
2.13
1.52
2.55
2.10
2.47
1.89
1.83
2.25
2.50
2.02
30
-------
The following is a copy of the PREHR.F program which was used to reformat the hourly data
from the NOAA format into a more compatible HYDHR format:
character* 12 filtat(3), filin, filnam, filin2, filog
character*3 rectypl
character* 8 staid
character*4 elmtypl, staid
character*2 eunitl; state, staidl
character*! flagl 1(100), flag21(100), typ, stal
character*5 stdumyl
dimension idayl(100),ihourl(100),ivaluel(100), value(31)
dimension isumyr(3), isumv2(3), iy(3), iso(100,4)
dimension isumv3(3), isumv4(3), my(3), PP(1100,4)
isumv2=0
isumv3=0
isumv4=0
' PP = 0
Write,(*,*)'Data extraction from NOAA Hourly data1
Write(*,*)lreformat for HSPF runs'
filin2 = 'prehr.lis'
open (8, file=filin2, access-sequential',status=lold')
read(8,*) nfil
read(8,66) filin
66 format(al2)
open (10, file=filin, access='sequential',status='old')
fihiam = 'xxxxxxx-out'
filog = 'xxxxxxx.log1
rewind(lO)
close(lO)
typ =
i2 = 2 ' -
i3 = 3
LR = 0
line = 0
do 200 m= 1,2000
line = line - 1
open (10, file=filin, access- sequentiar,status='old')
200 read(10, 39, end=49, err=49) rectypel
39 format(a3)
49 write(*,*) line
filnam(l:7) =
filog(l:7) =
31
-------
open(24,FILE=filnam,STATUS='unknown')
open (10, file=filin, access=lsequential',status='old')
do 100m=l,line
read(10, 33, end=40,err=40) ir, iyr, imn, idy, idum, Vdum,
l(valueG),j = l,12)
33 fonnat (i2, i2, 12, i2, i8, F8.0, 12f8.0)
40 write(24,205)filin(l:7),iyr,imn,idy,il,
l(valueO),j=l,12)
write(24,205) filin(l :7), iyr, imn, idy, i2,
205 format(a7, 3x, i2, Ix, i2, Ix,i2,lx,il, 12f5.2)
if(stal .eq. '18') state='MD'
if(stal .eq. '36') state='PA'
if(stal .eq. '44') state='VA1
if(stal .eq. '46') state='WV'
if(stal .eq. '07') state='DE'
if(stal .eq. '18') state=!MD'
if(stal .eq. '30') state='NY'
100 continue
close(lO)
close(24)
666 continue
end
32
-------
Section D.4 Simulation of the Atmospheric Deposition of Nutrients
D.4.1 Introduction
The atmospheric nutrient deposition inputs for the Phase IV Chesapeake Bay Watershed
Model consist of wet nitrate (NO3), dry NO3, organic nitrogen (OrN), organic phosphorus (OrP),
and dissolved inorganic phosphorus (DIP). The total amount of dry ammonia (NH4) deposited is
assumed to be negligible.
D.4.2 Wetfall Atmospheric Deposition of NO3 and NH4 for the Phase IV Chesapeake Bay
Watershed Model Precipitation Segments
The wetfall atmospheric deposition of NO3 and NH4 for the Phase IV Chesapeake Bay
Watershed Model precipitation segments was calculatedaccording to a regression model which was
developed by the Chesapeake Bay Program's Air Subcommittee7. The regression model is based
principally on the logarithmic relationship between the amount of precipitation and the NH3 and
NO3 concentrations in the precipitation. The regression relationship was developed using weekly
data collected over an eight year period at fifteen National Air Deposition Program (NADP) sites.
Due to the weekly pooled sampling protocol of NADP and concerns over transformation of the
nutrient species over time, the data were quality controlled by selecting those data where the
precipitation event occurred only on the last day of the weekly sample. Using this criteria, 265
samples were selected from the approximately 5,000 samples collected at the NADP sites. These
selected data were then treated as daily samples and employed in developing the regressionmodel.
The regression equation expresses the wetfall deposition of NO3 andNH4 as a function of
daily precipitation, latitude, and month of the year:
N[NO3] = 0.226 * exp(-0.3852 * ln(ppn) - 0.0037 * month2 + 0.0744 * latitude -1.289)
N[NH,] = 0.7765 * exp(-0.3549 * ln(ppn) + 0.3966 * month - 0.0337 * month2 -1.226)
where: Q is the concentration (in milligrams/liter) as N,
ppn is the precipitation (in millimeters),
the month is expressed as an integer, and
the latitude is the centroid Y component (in decimal degrees) of precipitation segments.
Load of N(rn kg/ha) = N[NO3 or NH,] * precipitation = (mg/L * ppn)/100.
The regression model was applied to the precipitation data to produce daily deposition rates
with the same spatial resolution as the Theissen distributed daily precipitation inputs. The annual
average wet nitrate and ammonia atmospheric deposition loads during 1984-1994 for the Phase IV
Chesapeake Bay Watershed Model precipitation segments are listed in Table D.4.1. Information
regarding the model segments and their corresponding precipitation segments can be found in Table
D.3.1.
'Valigura, RA., Luke, W.T., Artz, R.S., Hicks, B.B. (1996). Atmospheric Nutrient Input to Coastal Areas
— Reducing the Uncertainties. NOAA Coastal Ocean Program Decision Analysis Series No. 9. Silver Spring, MD.
33
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Table D.4.1
Average Annual Atmospheric Wet NO, and Wet NH4 Depositions for the Phase IV Chesapeake Bay Watershed Model
Precipitation Segments, 1984-1994
Average Annual Average Annual
Bay Watershed Model Wet NO3 Deposition Wet NH4 Deposition
Precipitation Segments Pound/acre Pound/acre
010 4.27 2.08
, 020 4.95 2.33
030 4.37 2.23
040 4.22 2.26
050 4.36 2.31
060 4.50 2.33
070 4.00 2.11
080 4.21 234
090 3.74 2.09
100 4.09 2.23
110 3.87 2.18
120 3.60 2.06
160 3.83 2.24
170 3.26 2.02
175 , 3.36 2.01
180 3.40 2.00
190 3.33 2.15
200 3.26 2.01
210 3.63 2.12
220 3.35 2.04
230 3.54 2.26
265 3.30 2.14
270 3.36 2.26
280 3.46 2.34
700 3.64 1.84
710 3.69 2.08
720 3.80 2.16
730 3.73 . 2.16
740 3.49 2.06
750 3.53 2.03
760 3.45 2.03
1001 3.10 2.00
1002 3.40 ' 2.10
1003 3.39 2.05
1004 3.71 2.14
1005 3.44 2.03
1006 3.20 2.00
1007 3.25 2.02
1008 3.20 2.10
1009 3.10 , 2.11
1010 ' 2.92 2.11
1011 3.46 2.09
1012 3.27 2.17
1013 3.16 2.18
34
-------
D.4.3Annual Wet Deposition of NO3 and NH4
The observed measurements of wetfall NO3 and NH4 as reported by the NADP for twelve
sites in and around the Chesapeake Bay watershed are listed in Table D.4.28. The average annual
wet NO3 and NH4 depositions derived from the regression equations (Table D.4.1.) are in the same
ranges of magnitude as the observed data (Table D.4.2). Of those values obtained through the
regression equations, watershed model precipitation segments 10-100 have the highest annual
average wet NO,3 and NH4 deposition loading rates. These precipitation segments are located in
the states ofNew York and Pennsylvania portions of the Susquehanna River basin. The NADP data
(Table D.4.2) show that most of the atmospheric air deposition stations in New York and
Pennsylvania generally have higher observed wet N03 andNR, deposition loading rates. The close
agreement of the NADP values to those obtained from the regression equations verifies the
application of the Chesapeake Bay Program Air Subcommittee regression simulation for the wet
NO3 and NH4 atmospheric deposition inputs for the Phase IV Chesapeake Bay Watershed Model.
A workshop sponsored by the Chesapeake Bay Program's Scientific and Technical
Advisory Committee evaluated more recent NADP data through 1994 showed that 1983-1994
average annual inorganic nitrogen deposition at the NADP sites within or near the Chesapeake
Basin range from 3.5kg N/ha-yr in southwestern Virginia to 7.7 kg N/ha-yr in northwestern
Pennsylvania9. The wetNO3 +NH4 atmospheric deposition loading rates ranged from 6 to 7 Ib/ac-yr
and the ratio of NO3-N to NI-^-N in wet deposition ranged from 1.3 to 2.5. These are consistent
with Phase IV Chesapeake Bay Watershed Model adopted wet NO3 and NH4 deposition values
presented in Table D.4.1.
D.4.4 Dry Atmospheric Deposition for NO3 and NH4
The wet/dry ratios ofN03 atmospheric deposition was determined through the wet/dry NO3
ratio estimated by the RADM model cells distributed tot he Phase TV Chesapeake Bay Watershed
Model segments and are listed in Table D.4.3. The annual average dry NO3 deposition, calculated
by dividing the annual average (1984-94) wet NO3 deposition by the corresponding wet/dry ratio,
is also presented in Table D.4.3. The wet-NO3 deposition was associated with precipitation, and,
therefore, was differentiated among precipitation segments (as presented in Table' D.2.1). Each of
the precipitation segments either corresponds to one model segment, or is aggregated from several
model segments (see Section D.3).
8 Valigura, R.A., Luke, W.T., Artz, R.S., Hicks, B.B. (1996). Atmospheric Nutrient Input to Coastal
Areas — Reducing the Uncertainties. NOAA Coastal Ocean Program Decision Analysis Series No. 9. Silver
Spring, MD.
9 Gardner, R.H., Castro, M.S., Morgan R.P., Seagle, S.W. (1996). Perspectives on Chesapeake Bay:
Nitrogen Dynamics in Forested Lands of the Chesapeake Basin. Chesapeake Bay Program Office. Annapolis, MD.
35
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Table D.4.2.3
Annual Wet Deposition of
NADP Site
White Rock, MD
Wye,MD
Lewiston, NC
Finely Farms, NC
Chautauqau, NY
Jasper, NY
Penn State, PA
Leading Ridge, PA
Milford, PA
Charlottesville, VA
Babcock State Park, WV
Parsons, WV
1985
2.65
2.63
1.76
1.82
5.17
2.15
3.52
3.83
3.93
3.35
3.03
4.90
1986
3.27
2.77
2.05
—
5.30
2.77
3.74
4.89
—
2.97
3.51
5.58
1987
3.27
2.23
2.19
226
3.47
2.68
4.03.
4.89
4.05
3.15
2.76
3.63
NO3 at NADP Sites (Pounds Nitrogen /Acre)
1988
3.50
2.33
2.34
2.65
3.85
2.54
2.90
3.60
3.69
2.65
1.86
3.46
1989
3.96
3.85
2.54
3.35
3.63
2.70
3.72
4.81
4.06
~
3.54
4.70
1990
3.43
3.14
2.06
2.03
4.25
2.69
4.03
4.73
4.52
3.22
2.80
3.80
1991
2.77
3.01
2.05
1.98
3.19
2.06
3.49
3.56
3.22
2.93
2.52
3.54
1992
3.11
2.49
2.20
1.64
3.55
2.74
3.70
3.60
3.78
3.28
2.82
3.74
1993
4.03
3.14
2.05
1.93
3.50
2.60
4.03
4.20
3.96
3.52
3.56
3.99
1994
3.70
3.38
1.67
1.74
3.09
3.04
3.84
3.75
4.56
3.21
2.71
4.43
1995
2.58
2.66
2.13
2.26
3.09
1.84
2.85
2.84
2.93
3.18
2.87
3.61
Table D.4.2.b
Annual Wet Deposition of
NADP Site
White Rock, MD
Wye,MD
Lewiston, NC
Finely Farms, NC
Chautauqau, NY
Jasper, NY
Penn State, PA
Leading Ridge, PA
Milford, PA
Charlottesville, VA
Babcock State Park, WV
Parsons, WV
1985
1.21
1.42
1.13
1.27
3.04
1.21
1.61
1.83
1.95
1.60
1.41
2.36
1986
1.67
1.50
1.22
—
3.73
1.27
1.50
2.27
~
1.57
1.78
2.69
1987
1.77
1.21
1.45
1.78
1.92
1.50
1.78
2.29
1.39
1.45
1.59
1.92
NH4 at NADP Sites (Pounds Nitrogen / Acre)
1988
1.53
1.05
0.72
1.33
2.16
1.16
1.26
1.58
1.04
0.97
0.77
1.25
1989
2.40
2.36
1.53
3.89
2.17
1.79
2.27
2.71
1.58
-
1.89
2.58
1990
2.00
1.91
1.67
2.29
2.58
1.54
2.08
2.56
2.06
2.20
1.77
1.98
1991
1.57
1.83
1.28
2.28
1.78
1.03
1.70
1.77
1.42
1.66
1.05
1.52
1992
1.75
1.53
1.58
1.80
1.99
1.57
1.80
1.78
1.69
1.72
1.42
1.65
1993
2.34
1.95
1.85
2.13
2.05
1.14
1.64
1.84
1.69
2.34
1.91
1.71
1994
2.25
; 2.11
1.32
1.80
1.64
1.81
1.89
1.83
2.17
2.01
1.55
2.48
1995
1.67
1.90
1.58
2.41
2.05
1.15
1.57
1.39
1.51
2.17
1.85
2.21
Constant annual dry NO3 deposition applied on a daily basis are used as the inputs of dry NO3
deposition for the Phase IV Chesapeake Bay Watershed Model.
36
-------
Table D.4.3
Average Annual Wet & Dry NO3 Atmospheric Deposition Loading
Rates
(Pounds-Nitrogen / Acre-Year)
Phase IV Watershed
Model Segment
10
20
30
40
50
60
70
80
90
100
' 110
120
140
rl60
170
175
180
190
200
210
220
230
235
240
250
260
265
270
280
290
300
310
1984-1994
Annual Average
Wet NO3 Atmospheric
Deposition
4.27
4.95
4.37
4.22
4.36
4.50
4.00
4.21
3.74
4.09
3.87 •
3.60
3.71
3.83
3.26
3.36
3.40
3.33
3.26
3.63
3.35
3.54
327
327
3.27
3.27
3.30
3.36
3.46
3.16
3.16
3.16
Wet/Dry Ratio of
NO3 Atmospheric
Deposition
0.99
1.07
1.08
1.07
1.14
1.08
1.05
1.07
1.17
1.13
1.05
1.01
1.01
1.18
1.14
1.13
1.05
1.02
1.08
1.02
1.01
1.01
0.96
0.93
0.95
0.93
0.99
0.88
0.91
0.90
0.87
0.87
Estimated
Annual Average
Dry NO3 Atmospheric
Deposition
4.32
4.63
4.04
3.95
3.82
4.17
3.81
3.93
3.20
3.62
3.69
3.56
3.67
3.25
2.86
2.98
324
321
3.02
3.56
3.31
3.50
3.40
3.51
3.44
3.51
3.34
3.82
3.81
3.51
3.63
3.63
37
-------
Table D.4.3 continued
Phase IV Watershed
Model Segment
330
340
370
380
390
400
410
420
430
440
450
470-
480
490
500
510
540
550
560
580
. 590
600
610
620
630
650
700
710
720
730
740
750
760
770
780
800
810
1984-1994
Annual Average
Wet NO3 Atmospheric
Deposition
3.46
3.46
3.39
3.39
3.40
3.40
3.40
3.10
3.10
3.10
3.71
3.44
3.44
3.44
3.20
3.44
3.25
325
3.20
3.20
3.10
3.10
3.10
2.92
2.92
3.44
3.64
3.69
3.80
3.73
3.49
3.53
3.45
3.40
3.40
3.39
3.39
Wet/Dry Ratio of
NO3 Atmospheric
Deposition
0.99
0.99
0.99
0.99
0.99
0.99
0.97
0.95
0.94
0.90
1.00
1.01
0.99
0.99
0.97
0.99
0.98
0.99
0.92
0.90
0.90
0.88
0.90
0.86
0.84
1.00
1.01
1.03
1.03
1.10
1.10
1.05
1.00
0.99
0.99
0.99
0.99
Estimated
Annual Average
Dry NO3 Atmospheric
Deposition
3.49
3.49
3.42
3.42
3.44
3.44
3.51
3.26
3.30
3.45
3.71
3.40
3.47
3.47
3.30
3.47
3.32
3.28
3.48
3.56
3.45
3.53
3.45
3.40
3.48
3.44
3.60
3.58
3.69
3.40
3.18
3.37
3.45
3.44
3.44
3.42
3.42
38
-------
Table D.4.3 continued
Phase IV Watershed
Model Segment
820
830
840
850
860
870
880
890
900
910
920
930
940
950
960
970
980
990
1984-1994
Annual Average
Wet NO3 Atmospheric
Deposition
3.40
3.40
3.40
3.71
3.44
3.44
3.20
3.25
3.25
3.20
3.20
3.20
3.10
2.92
2.92
3.25
3.20
3.20
Wet/Dry Ratio of
NO3 Atmospheric
Deposition
0.99
0.98
0.96
1.00
0.99
0.99
0.98
0.98
0.98
0.97
0.95
0.90
0.89
0.86
0.86
0.97
0.94
0.94
Estimated
Annual Average
Dry NO3 Atmospheric
Deposition
3.44
3.47
3.54
3.71
. 3.47
3.47
3.26
3.32
3.32
3.30
3.37
3.56
3.49
3.40
3.40
3.35
3.41
3.40
D.4.5 Atmospheric Deposition for Organic Nitrogen.
Organic nitrogen is only represented as wet atmospheric deposition of dissolved organic
nitrogen (DON). This is because the magnitude of the dry fall organic nitrogen is currently
unknown and, therefore, not accounted for separately. Organic nitrogen remains the least well
characterized of all the nitrogen species in atmospheric deposition.
It is useful to utilize previous studies' data to understand the magnitude of the values being
incorporated into the Phase IV Chesapeake Bay Watershed Model. Dissolved organic nitrogen has
considerable seasonal variability with the seasonal high occurring from April to June and the
seasonal low from July to March10. Organic nitrogen measurements from Bermuda collected by
10 Smullen, J.T., Taft, J.L., Macknis, J. (1982). Nutrient and Sediment Loads to the Tidal Chesapeake
Bay System. U.S. EPA Chesapeake Bay Program Technical Studies. Chesapeake Bay Program Office, Annapolis,
MD.
39
-------
Knap and co-workers (1986) were calculated atabout 100 ug/1 (as N)11. Moper and Zika (1987)
reported an average DON concentration from the western Atlantic and Gulf of Mexico of about 100
ug/1 (as N)12. This is consistent with the reported range of concentrations from the North Sea and
Northeast Atlantic of between 90 ug/1 to 120 ug/113. A recent study reported an annual volume
weighted avereage DON concentration in the mid-Atlantic coastal areas to be about 130 ug/1 (as
N)14. The measurements in this study are consistent with the interannual variation (maximum in
spring) reported hi previous studies15.
»
According to the studies focused on the mid-Atlantic coastal areas, 130 ug/1 (as N) is
regarded as representative of an average annual DON wet deposition concentration14. Based on
these studies, an average concentration of 98 ug/1 for July to March rainfall and an average
concentration of'224 ug/1 for April to June rainfall were applied to the Chesapeake Bay watershed
and tidal surface waters as part of the Phase IV model. Table D.4.4 summarizes the 1984-1991
average annual DON loading rates by the Phase IV watershed model precipitation segments.
D.4.6 Atmospheric Deposition for Organic P and Inorganic Phosphate
Daily atmospheric deposition loads of organic phosphorous (OrP) and inorganic phosphate
(DIP) are employed hi the Phase IV Chesapeake Bay Watershed Model. The annual loading rates
are 0.423 Ib/ac for P[Organic P] and 0.143 Ib/ac for PpPhosphate]16. The yearly loads were evenly
allocated as daily loads for model input throughout all of the Phase IV watershed model segments.
D.4.7 Atmospheric Deposition to Chesapeake Bay Water Quality Model Cells
Inputs of atmospheric deposition of nutrients to the mainstem Bay and tidal tribuaries'
surface waters—Chesapeake Bay Water Quality Model—utilizes the atmospheric deposition data for
the coastal Phase IV Chesapeake Bay Watershed Model. As mentioned hi Sections D.4.2-D.4.5,
the atmospheric NO3, NH4, and DON depositions were calculated and associated with precipitation,
therefore, in order to utilize the atmospheric nutrient deposition of the Watershed Model for the
11 Knap, A., Jickells, T., et al. (1086). Significance of atmospheric-derived fixed nitrogen on productivity
of the Sargasso Sea. Nature 320 (3/13): 158-160.
12 Moper, K., Zika, R.G. (1987). Free amino acids in marine rain: Evidence for oxidation and potential
role in nitrogen cycling. Nature 325:246-249.
13 Scudlark, J.R., Church, T.M. (1993). Atmospheric input of inorganic nitrogen to Delaware Bay.
Estuaries 16(4): 747-754.
14 Scudlark, J.R., Russel, K.M., et al. (1996) Dissolved Organic Nitrogen in Precipitation: Collection,
Analysis, and Atmospheric Flux. Report to: Maryland Department of Natural Resources, Annapolis, MD.
15 Smullen, J.T., Taft, J.L., Macknis, J. (1982). Nutrient and Sediment Loads to the Tidal Chesapeake Bay
System. U.S. EPA Chesapeake Bay Program Technical Studies. Chesapeake Bay Program Office, Annapolis, MD.
16 .(1982). Technical Studies: A Synthesis. U.S. Environmental Protection Agency. Chesapeake
Bay Program Office. Annapolis, MD.
40
-------
Chesapeake Bay Water Quality Model, a development or allocation of the watershed precipitation
to the 3D water quality model cells is necessary.
Arc/Info software was applied to data supplied by the Waterways Experimental Station of the U.S.
Army Corps of Engineers on a grid with 2100 surface cells in order to divide the SD-cells into eight
precipitation regions. The 3D-cells were divided based upon the NADP station's proximity to the
Chesapeake Bay and the boundaries of the precipitation regions. Figure D.4.2 illustrates the eight
precipitation regions for the 3D model cells. Each of the Bay Water Quality Model precipitation
regions is associated with one coastal Chesapeake Bay Watershed Model precipitation segment
(Table DAS, Figure D.4.3).
Table D.4.4
Phase IV Chesapeake Bay Watershed Model Precipitation Segments 1984-1991 Average Annual
Atmospheric Dissolved Organic Nitrogen Atmospheric Deposition Loading Rates (Pounds Nitrogen/Acre-
Phase IV Watershed
Model Precipitation
Segment
10
20
30
40
50
60
70
80
90
100
110
120
160
170
175
180
190
200
210,
220'
230
265
270
280
Average Annual
DON Deposition
Loading Rate
1.02
1.18
1.19
1.24
1.26
1.19
1.14 '
1.19
1.13
1.13
1.19
1.17
1.19
1.00
1.06
1.10
1.18
1.07
1.21
1.19
1.30
1.18
1.23
1.34
Year)
Phase IV Watershed
Model Precipitation
Segment
700
710
720
730
740
750
760
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
Average Annual
DON Deposition
Loading Rate
1.00
1.15
1.24
.24
.10
.22
.17
.13
.17
.24
.16
.15
.16
.17
.21
.22
.25
.24
1.27
1.26
Table 0.4.5 shows the atmospheric nitrogen deposition to the Chesapeake Bay Watershed
based upon 1991 landuse data and 1984-1994 annual average loads.
41
-------
Table 0.4.5
1984-1994 Annual Average Atmospheric Nitrogen Deposition Loads to the Chesepeake
Bay Watershed
(based on 1991 landuse as analyzed on March 16,1997 at the Chesapeake Bay Program Office)
Mode! Wet-NO3 Wet-NH4 Dry-NO3 DON TN
Segment thousand Ibs/yr thousand Ibs/yr thousand Ibs/yr thousand Ibs/yr thousand Ibs/yr
10 7223 3512 7296 1738 19770
20 15733 7407 14704 3764 41609
30 6114 3121 5661 1673 16569
40 4015 2148 3753 1188 11104
50 3985 2113 3496 1160 10754
60 12270 6350 11361 3246 33228
70 3400 1794 3239 975 9408
80 6142 3418 5740 1748 17047
90 . 2245 1256 1919 678 6097
100 6326 3443 5599 1748 17116
110 4385 2463 4176 1358 12382
120 475 271 470 154 1370
140 689 397 682 217 1986
160 3311 - 1932 2806 1030 9080
170 3093 1917 2714 959 8683
175 2710 1616 2398 855 7580
180 1392 820 1326 454 3992
190 3466 2239 3398 1228 10330
200 2939 1814 2721 971 8445
210 ~ 1862 1089 1826 623 5400
220 2042 1244 2022 732 6041
230 3635 2324 3599 1344 10901
235 537 357 559 . 209 1662
240 705 468 758 . 274 2205
250 698 464 735 . 272 2169
260 1539 1022 1655 599 4815
265 738 477 745 264 2224
270 6289 4236 7147 2316 19987
280 6692 4513 7353 2593 21151
290 1040 717 1156 418 3331
300 2415 1664 2776 970 7825
310 320 220 367 128 1036
330 294 177 297 , 106 875
340 475 287 480 172 1414
370 128 78 129 47 382
380 .898 .544 907 330 2680
390 196 121 198 68 582
400 1025 633 1035 355 3048
410 1575 974 1624 546 4719
420 423 272 446 155 1296
430 1482 953 1576 541 4552
440 637 410 . 708 232 1987
450 1758 1014 1758 553 5082
470 1000 590 990 335 2916
480 271 160 273 91 795
490 341 201 345 114 1002
500 1068 666 1101 388 3223
510 104 61 105 35 306
540 336 209 343 121 1009
550 1301 810 1315 470 3896
560 2003 1311 2177 ' 761 6251
42
-------
Table 0.4.5
1984-1994 Annual Average Atmospheric Nitrogen Deposition Loads to the Chesepeake
Bay Watershed
(based on 1991 landuse as analyzed on March 16,1997 at the Chesapeake Bay Program Office)
DON
TN
Model Wet-NO3 Wet-NH4 Dry-NO3
Segment thousand Ibs/yr thousand Ibs/yr thousand Ibs/yr thousand Ibs/yr thousand Ibs/yr
580
590
600
610
620
630
650
700
710
720
730
740
750
760
770
780
800
810
820
830
840
850
860
870
,880
890
900
910
320
930
940
950
960
970
980
990
Total
133
1826
2650
492
414
53
358
564
572
1153
1191
306O
379
272
243
154
173
366
91
296
942
204
203
94
369
189
461
515
1258
102
778
184
450
119
1229
67
155347
87
1239
1798
334
298
38
211
285
323
656
688
1802
218
160
150
95
105
222
56
183
582
117
120
55
230
118
287
321
785
67
528
133
324
74
804
42
89838
147
2029
3012
547
481
63
358
559
555
1120
1082
2781
361
272
245
156
175
370
92
302
981
204
205
95
377
193
470
530
1324
113
874
214
523
123
1307
71
152277
50
722
1048
195
178
23
122
156
180
377
395
967
131
93
84
54
63
134
32
103
326
64
68
31
134
68
166
187
457
39
308
79
193
43
467
24
49067
"417
5817
8508
1568
1371
178
1049
1563
1630
3305
3356
8609
1090
798
722
459
515
1092
272
884
2831
589
596
275
1111
568
1385
1553
3824
320
2487
611
1489
360
3807
205
446530
43
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Table D.4.6
Correspondence of Phase IV Chesapeake Bay Watershed Model Precipitation Segments
with the Chesapeake Bay Water Quality Model Precipitation Regions
Chesapeake Bay Water Quality Phase IV Watershed Model
Precipitation Regions Precipitation Segments
1 1001
2 1009
3 1010
4 1004
5 - 1005
6 1006
7 1007
8 1008
Building on the above established linkages between the grouping of Bay Water Quality
model cells and Chesapeake Bay Watershed Model precipitation segments, the same loading rates
(Ib/ac-yr) for NO3, NH4, and DON atmospheric deposition developed for each respective
Chesapeake Bay Watershed Model precipitation segment is applied to the correspondingBay Water
Quality Model precipitation region (Table D.4.6).
As determined for the Phase IV Chesapeake Bay Watershed Model segments, OrP and PO4
atmospheric deposition loading rates were assumed to be constant (P [Organic P] at 0.423 Ib/ac, and
P [PO4] at 0.143 Ib/ac), and the yearly loads were evenly allocated as daily load for input into all
Chesapeake Bay Water Quality Model Cells.
As with all Chesapeake Bay Watershed Model segments, the dry NH» atmospheric
deposition loading rate is assumed to be zero for all the Chesapeake Bay Water Quality Model
cells.
The dry NO3 atmospheric deposition loading rates for each Chesapeake Bay Water Quality
Model cell were calculated as thirty percent of their corresponding watershed precipitation
segment's 1984-1994 annual average wetNO3 deposition, because a long-term average of wet/dry
fall nitrate to open water that is wider than about 5 meters is 3.3317. Table D.4.3 lists the dry-NO3
17 Valigura, R.A., Luke, W.T., Artz, R.S., Hicks, B.B. (1996). Atmospheric Nutrient Input to Coastal
Areas — Reducing the Uncertainties. NOAA Coastal Ocean Program Decision Analysis Series No. 9., MD. v
44
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Figure D.4.1
Chesapeake Bay Water Quality Model Cells
PW Map Date: July 24.1997 n»H.lKinieV«ig/iaiip/sB/»i:7/aiv/
Source: USEPA Chesapeake Bay Program Office
45
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Figure DA2
Chesapeake Bay Water Qaulity Model Precipitation Regions
RegionS
Region?
PW Map Dae July». 1997
Source: USEPA Chesapeake Bay Program Office
46
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Figure DAS
Chesapeack Bay Water Qaulity Model Precipitation Region with the Corresponding
Coastal Phase IV Chesapeake Bay Watershed Model Precipitation Regions
Region I
Region 2
Region 3
Region 4
Region 6
Region?
RegionS
^VYYVVV Vyy YYY Y VYYY
YYYYYYYYYJgyYYYYYYYYV
wyyxxxvyyxxxxxxxxx
1 —8: Water Qaulity Model Precipitation Regions
1000s: Coastal Watershed Model Precipitation Segments
PW Mip Dae July 24,1997
Source: USEPA Chesapeake Bay Program Office
47
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versus wet-NO3 ratios for the eight precipitation regions of the Chesapeake Bay Water Quality
Model cells.
Table D.4.7
Wet and Dry NO, Atmospheric Deposition Loading Rates for the Chesapeake
Chesapeake Bay
Water Quality Model
Precipitation Region
Region 1
Region 2
Region 3
Region 4
Region 5
Region 6
Region 7
Region 8
Bay Water Quality
1984-1994 Annual
Average Wet NO,
(Pounds-Nitrogen/
Acre-Year)
3.10 .
3.10
2.92
. 3.71
'3.44 l
320
325
3.20
Model Precipitation Regions
Wet/Dry Ratio
3.33
3.33
3.33
3.33
3.33
3.33
3.33
3.33
1984-1994 Annual
Average Dry NO,
(Pounds-Nitrogen/
Acre-Year)
0.93
0.93
0.88
1.11
1.03
0.96
0.97
0.96
48
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XX
x
—'—™ii3Effi~;nirt*«*
Chesapeake Bay Program
U.S. Environmental Protection Agency
Chesapeake Bay Program Office
410 Severn Avenue, Suite 109
Annapolis, MD 21403
1-SOO-YOURBAY
www.epa.gov/chesapeake
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