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Middle Potomac Watershed Assessment
Modeling Streamflows
Third of a six-part webinar series
June 16, 2011
The webinar will start momentarily.The webinar will start momentarily.
Audio feed is by telephone
Toll-Free: (888) 296-1938
When prompted, enter Participant Code: 516128
Please mute your phone by selecting *6.
16/16/2011
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Middle Potomac Watershed Assessment
Modeling Streamflows
Speakers
Andrew Roach, U.S. Army Corps of Engineers, Baltimore District
Heidi Moltz, Senior Water Resources Scientist, Interstate Commission
on the Potomac River Basin (ICPRB)
2
Project website: http://potomacriver.org/sustainableflows
6/16/2011
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Study Area
6/16/2011 3
3
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Objectives
1) Estimate current and future human water withdrawals and their
impacts on flows.
2) Characterize flows needed to support healthy stream biotic
communities. communities.
3) Provide baseline information and analyses to support water use
decision making.
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Webinar Series
� Technical details on methodology for small streams
� Obtain feedback from stakeholders
� Prepare for concluding workshop: focus on management applications
Date Webinar Topic
April 12 Technical overview of project
May 10 Current and future demands and impacts on flow
5
May 10 Current and future demands and impacts on flow
June 16 Modeling streamflows
July 14
Quantitative flow-ecology relationships Part 1:
Data, variables, and methodology
Sept 8
Quantitative flow-ecology relationships Part 2:
ELOHA curves, uncertainty, and interpretation
Oct 27 From science to management applications
Nov 29-Dec 1 Flow ecology response workshop at NCTC
6/16/2011 Project website: http://potomacriver.org/sustainableflows
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Hydrologic Foundation
66/16/2011
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Modeling Streamflows Objective
Develop flow time series for select watersheds from
which flow alteration will be estimated which flow alteration will be estimated
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Modeling Process
� Identify and delineate watersheds
� Select hydrologic simulation model
� Improve model components where possible
� Establish watersheds in model environment
� Calibrate model
� Develop scenarios
� Run model
� Evaluate output
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Criteria for Selection
of Biological Monitoring Points
� Best biologic sites
across range of
hydrologic alteration
� Range of watershed
sizessizes
� Broad spatial
distribution
� Within 200’ of NHD
streams
783 biological monitoring
points selected
9
Biological data obtained from local, state, and federal programs and assembled
in the Chessie B-IBI database by the Chesapeake Bay Program.6/16/2011
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Watershed Delineation
Multi-watershed delineation tool, Utah State University
10http://hydrology.usu.edu/mwdtool6/16/2011
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Watersheds Draining
to Biological Monitoring Points
574 NEAFWA
Headwater/Creek
Watersheds
(< 38.6 sq. mi.)
116/16/2011 NEAFWA = Northeast Association of Fish and Wildlife Agencies
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Watersheds Draining
to Biological Monitoring Points
92 NEAFWA
Small River Watersheds
(38.6 - 200 sq. mi.)
126/16/2011 NEAFWA = Northeast Association of Fish and Wildlife Agencies
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Watersheds Draining
to Biological Monitoring Points
39 NEAFWA Medium
River Watersheds
(200 - 1,000 sq. mi.)
136/16/2011 NEAFWA = Northeast Association of Fish and Wildlife Agencies
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Watersheds Draining
to Biological Monitoring Points
7 NEAFWA
Large/Great River
Watersheds
(>1,000 sq. mi.)
712 total watersheds
146/16/2011 NEAFWA = Northeast Association of Fish and Wildlife Agencies
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Distribution of Watershed Sizes
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Watershed Land Cover Distribution
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Watershed Bioregion Distribution
Number of Watersheds
Chessie B-IBI
Bioregions
Coastal
Plain33
176/16/2011
Plain
Ridges 254
Piedmont 217
Valleys 208
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Model Selection
186/16/2011
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WOOOMM Benefits
CBP model output locations WOOOMM output locations
19
WOOOMM: Online Object Oriented Meta-Model6/16/2011
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WOOOMM Components
Chesapeake Bay
Program
Phase 5.2 Model
20
Watershed illustration
by Jane MacQueen
WOOOMM: Online Object Oriented Meta-Model6/16/2011
USGS Channel
Morphology Model
WOOOMM
channel routing
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WOOOMM Data Inputs
Model Inputs
� Watershed inputs
� Unique ID
� Watershed routing
� CBP outputs
� Physical characteristics
� Meteorology
� Area
� Channel routing/morphology
� Dominant physiographic
province
� Channel slope
� Channel length
� Anthropogenic activities
� Withdrawals
� Discharges
� Impoundments
� Land use
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Nested Watershed Simulation, WOOOMM
22Marsh, Rock, and Alloway Creeks – Upper Monocacy Watershed6/16/2011
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WOOOMM Simulation Areas
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WOOOMM, A Look Inside
6/16/2011 24
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CBP Model Enhancements
Chesapeake Bay Program (CBP) Phase 5.2 model
enhancements
� Non-linear groundwater recession� Non-linear groundwater recession
� Re-segmentation at “significant” impoundments
� CBP model includes 4 impoundments in the Potomac Basin –
Jennings Randolph, Savage Reservoir, Stony River Dam, and T.
Nelson Elliot
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Non-linear Groundwater Recession
� Linear, one-parameter, groundwater recession models tend to under-simulate low flows
� CBP Phase 5.2 was enhanced with a non-linear groundwater algorithm
� Results show modest low flow improvements
� This update is expected to be included in the CBP Phase 5.32 model
266/16/2011
Linear
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Model Re-segmentation Criteria
1. Significant
� >10% mean
annual flow
� Hydroelectric
+
27
+
2. Biological
monitoring points
upstream and
downstream
=
12 impoundments
22 new segments
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Selected Impoundments for
Model Re-segmentation
28
Impoundment information as reported in the National Inventory of Dams6/16/2011
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Model Re-segmentation Locations
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Model Calibration and Evaluation
CBP HSPF auto-calibration routine
“iterative procedure which links adjustments in parameter values
to the statistics comparing observed and simulated flows at [~46]
calibration stations [USGS gages]”
Hydrology calibration parameters (from CBP documentation)
30
Parameter Description
LAND_EVAP PET adjustment (similar to pan evaporation coefficient)
INFILT Base infiltration rate
LZSN Lower zone soil moisture storage index
AGWR Baseflow recession coefficient
INTFW Ratio of interflow to surface runoff
IRC Interflow recession coefficient
AGWTP Evapotranspiration from groundwater storage
Hydrology calibration parameters (from CBP documentation)
6/16/2011
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Nash Sutcliffe CBP Model Efficiency,
Daily Flows
316/16/2011
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CBP Model Efficiency, Daily Flows
326/16/2011
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WOOOMM Results Screening
screened watersheds for “reasonable” flow:area ratio
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Model Scenarios
Current
Baseline
Future (through 2030)Future (through 2030)– Domestic and Public Supply 1 (DP1)
– Domestic and Public Supply 2 (DP2)
– Power
– Hot and Dry
– Climate Change
(details on future scenarios presented at May 10th webinar -http://potomacriver.org/sustainableflows/)
346/16/2011
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Model Scenarios
Land Use Withdrawal Discharge Impound Temperature Precipitation
Baseline>78% forest, <0.35%
impervious cover0 0 0 CBP (84-05) CBP (84-05)
Current
2000 RESAC converted
to P5 land use
categories
ICPRB 2005
CBP point
source
database, 2005
16 CBP (84-05) CBP (84-05)
DP 1CBP 5.1 future
projections
per capita increase
0%withdrawal - CU 16 CBP (84-05) CBP (84-05)
projections 0%
DP 2CBP 5.1 future
projections
per capita increase
1.82%withdrawal - CU 16 CBP (84-05) CBP (84-05)
PowerCBP 5.1 future
projections
Projected and
additional power
plant and retrofits
withdrawal - CU 16 CBP (84-05) CBP (84-05)
Hot and DryCBP 5.1 future
projections
DP2 base with
increases in DP, PO,
and irrigation
withdrawal - CU 16 10.8% increase
(1930 drought)
Decrease
(1930 drought v
“normal” year)
Climate
Change
CBP 5.1 future
projections
per capita increase
4.38%withdrawal - CU 16
0.4C increase by
2030CBP (84-05)
35
DP = domestic and public supply
CU = consumptive use
CBP = Chesapeake Bay Program6/16/2011
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Withdrawals and Discharges
Current scenario:
� 2005 reported surface
water withdrawals,
permitted point source
discharges
Baseline scenario:Baseline scenario:
� No withdrawals, no
discharges
Future scenario:
� No new withdrawals or
discharges, projected
changes in use
366/16/2011
Simulated by latitude and longitude, rather than CBP WDM format
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Land Uses
Phase 5.2 Description
Water
High Intensity Impervious Urban
Low Intensity Impervious Urban
High Intensity Pervious Urban
Low Intensity Pervious Urban
Forest
Harvested Forest
Extractive
Bare-construction
Animal Feeding Operations
RESAC land uses
Open Water
Low Intensity, Developed
Medium Intensity Developed
High Intensity, Developed
Transportation
Urban/Residential Deciduous Tree
Urban/Residential Evergreen Tree
Urban/Residential Mixed Tree
Urban/Residential/Recreational Grass
Current scenario:
� Spatially explicit 2000 RESAC
land uses converted to P5.2
land use categories
Baseline scenario:
6/16/2011 37
Animal Feeding Operations
Alfalfa
High Till Crop without manure
High Till Crop with manure
Hay without nutrients
Hay with nutrients
Low Till Crop with Manure
Alfalfa with Nutrient Management
High Till Crop with Manure and
Nutrient Mgmt
High Till Crop with Nutrient Mgmt
Hay with nutrients and Nutrient
Mgmt
Low Till Crop with manure and
Nutrient Mgmt
Pasture with Nutrient Mgmt
Pasture
Trampled Pasture
Nursery
Urban/Residential/Recreational Grass
Extractive
Barren
Deciduous Forest
Evergreen Forest
Mixed (Deciduoud-Evergreen) Forest
Pasture/Hay
Croplands
Natural Grass
Deciduous Wooded Wetland
Evergreen Wooded Wetland
Emergent (Sedge-Herb)Wetland)
Mixed Wetland
Baseline scenario:
� >=78% forest
� <=0.35% impervious cover
Future scenario:
� CBP projected land uses
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Select Preliminary Results
Reference Watershed
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Select Preliminary Results
Reference Watershed
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Select Preliminary Results
Urban Watershed
Current scenario conditions:
� 2 sq. mi.
� 8% forest
� 0.2% agriculture
� 84% urban
� 20% impervious
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Select Preliminary Results
Large Watershed
Current scenario conditions:
� 3,050 sq. mi.
� 56% forest
� 36% agriculture
� 9% urban
� 0.86% impervious
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Select Preliminary Results
Impounded Watershed
Current scenario conditions:
� 105 sq. mi.
� 88% forest
� 2.5% urban
� 8.5 % agriculture
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Select Preliminary Results
Surface Water Withdrawals
Current scenario conditions:
� 9 sq. mi.
� 76% forest
� 14% agriculture
� 11% urban
� 1% impervious
6/16/2011 43
� 1% impervious
� 764 MGY surface withdrawal
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Limitations
� Extreme (high and low) flows
� Sub-daily flows
� Potential error sources� May differ between watersheds
� Scale of watersheds (very large to very small)
� Geology, slope, etc.� Geology, slope, etc.
� Calibration locations primarily on larger watersheds
� Resolution of model inputs compared to watershed sizes� (ex. precipitation)
But…
� Purpose is to evaluate relative difference in flows between scenarios (% alteration) – not to obtain absolute flow values
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Next Steps
456/16/2011
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Webinar Series
� Technical details on methodology for small streams
� Obtain feedback from stakeholders
� Prepare for concluding workshop: focus on management applications
Date Webinar Topic
April 12 Technical overview of project
46
May 10 Current and future demands and impacts on flow
June 16 Modeling streamflow
July 14
Quantitative flow-ecology relationships Part 1:
Data, variables, and methodology
Sept 8
Quantitative flow-ecology relationships Part 2:
ELOHA curves, uncertainty, and interpretation
Oct 27 From science to management applications
Nov 29-Dec 1 Flow ecology response workshop at NCTC
6/16/2011
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Conclusion
Questions? Comments?
Heidi Moltz, Ph.D.Heidi Moltz, Ph.D.
301.274.8116
http://potomacriver.org/sustainableflows/
476/16/2011
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Discussion
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