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Chesapeake Bay Watershed Model Overview

Chesapeake Bay Watershed Model Overview. Jing Wu UMCES/CBPO Modeling Group. February 4, 2010. Watershed Model Overview. HSPF model 101 Features of Phase 5 model Uses for management. Chesapeake Bay Program Decision Support System. Land Use Change Model. Criteria Assessment Procedures.

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Chesapeake Bay Watershed Model Overview

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  1. Chesapeake Bay Watershed Model Overview Jing Wu UMCES/CBPO Modeling Group February 4, 2010

  2. Watershed Model Overview • HSPF model 101 • Features of Phase 5 model • Uses for management

  3. Chesapeake Bay ProgramDecision Support System Land Use Change Model Criteria Assessment Procedures Bay Model Watershed Model Management Actions Scenario Builder Airshed Model Sparrow Effects Allocations

  4. HSPF Model • HSPF (Hydrological Simulation Program –Fortran) • Open source, free • Supported by USGS and EPA • Heavily parameterized (sensitive to many inputs) • Recommended for TMDLs

  5. Rainfall Snowfall Temperature Evapotranspiration Wind Solar Radiation Dewpoint Cloud Cover Land Use Acreage BMPs Fertilizer Manure Atmospheric Deposition Point Sources Septic Loads HSPF Modeling Process 1. Watershed Divided into sub-watershed ‘segments’ 2. Model is fed hourly values for meteorological forcing functions 3. Model is fed a particular snapshot of management options Flow and loads at various time scales

  6. High Density Pervious Urban High Density Impervious Urban Low Density Pervious Urban Low Density Impervious Urban Construction Extractive Wooded Disturbed Forest Corn/Soy/Wheat rotation (high till) Corn/Soy/Wheat rotation (low till) Other Crops Alfalfa Nursery Pasture Degraded Riparian Pasture Animal Feeding Operations Fertilized Hay Unfertilized Hay Nutrient management versions of the above Each segment consists of separately-modeled land uses Plus Point Source and Septic 6

  7. Surface Interflow Lower Zone Ground Water Each Land Use type is divided into four soil Layers Water, Sediment, Nitrogen, Phosphorus 7

  8. Export Export Export Export Export Export Export A complex nutrient cycling structure Trees Denitrification Roots Leaves Nitrate Atmospheric Deposition Particulate Particulate Solution Labile Refractory Ammonia Organic N Organic N Solution Solution Adsorbed Labile Refractory 8 Ammonia Organic N Organic N

  9. River Simulation River 3

  10. Hourly Values: Rainfall Snowfall Temperature Evapotranspiration Wind Solar Radiation Dewpoint Cloud Cover Annual or Monthly: Land Use Acreage BMPs Fertilizer Manure Atmospheric Deposition Point Sources Septic Loads Watershed Model Calibration HSPF Daily outputs compared to observations

  11. Hourly Values: Rainfall Snowfall Temperature Evapotranspiration Wind Solar Radiation Dewpoint Cloud Cover Snapshot: Land Use Acreage BMPs Fertilizer Manure Atmospheric Deposition Point Sources Septic Loads Watershed Model Scenarios Hourly output is summed over 10 years of hydrology to compare against other management scenarios HSPF “Average Annual Flow-Adjusted Loads” 11

  12. Year Segs Years Land Uses Purpose 1982 64 2 5 Split point source and nonpoint source 1985 64 2 5 Establish 40% goal 1992 64 4 8 Define 40% by basins 1994 89 8 9 Simulate nutrient cycle in more detail 1997 89 8 9 Re-evaluate and redefine 40% by major basin 2000 94 11 9 Set new goals and distribute by major subbasin 2010 1000 22 25 TMDL Watershed Model History Management questions and model have been both increasing exponentially in complexity. 12

  13. Phase 5 Model Development Phase 4 Phase 5 13

  14. Co-Developers of Phase 5 Model MDE VA DCR Chesapeake Bay Program Developers EPA UMCES USGS NRCS CRC VPISU $ ICPRB $ $ Advisors and data suppliers NY, PA, MD, DE, VA, WV, DC STAC USGS

  15. Major Advances in Phase 5 • Finer segmentation • Flexible functionality • High resolution input data • Automated calibration • Transferability

  16. Finer Segmentation Phase 5 – A ten fold increase in segmentation over previous phase 4.3 model Phase 4.3 land and river segments Phase 5 land segments Phase 5 river segments

  17. Flexible Functionality • Normal HSPF editing modes • hand-edited ASCII files • windows-based point-and-click database • GIS-based population • CBP phase 5 software • Automated file creation and modification in a linux scripting environment

  18. Flexible Functionality WDM = HSPF-specific binary file type UCI = User Controlled Input (input file) MET WDM ATDEP WDM PS WDM Land Input File Generator River Input File Generator 4 1 External Transfer Module 2 3 5 Land variable WDM River variable WDM Final Text Output 6 • Land UCIs are generated • HPSF is run on the land UCIs and output is stored in individual WDMs • The ETM is run converting land output to river input, incorporating land use, BMPs, and land-to-water delivery factors. Output is stored in river-formatted WDMs • River UCIs are generated • HSPF is run on the river UCIs and output is written back to WDMs • Postprocessor reads river WDMs and writes ASCII output

  19. Overall Software System Functionality • Advantages of phase 5 model system over • a traditional HSPF application: - Inserted software that allows extreme flexibility -- Time Varying Land Use/BMPs -- BMP efficiency reacting to hydrologic condition -- Simulate any described management practice - Easily allows large-scale parameter adjustments during calibration - Parallel computing operations convenient - Easy to add new land use types - Easily integrated into outside databases for scenarios

  20. Precipitation Temperature Evapotranspiration Wind Solar Radiation Dewpoint Cloud Cover Land Use Acreage BMPs Fertilizer Manure Atmospheric Deposition Point Sources Septic Loads Better, extended, and finer scale data sets Improved Input Data Simulation period is 1984-2005: Two decades of meteorology and watershed management data 20

  21. Scenario Builder Snapshot: Land Use Acreage BMPs Fertilizer Manure Atmospheric Deposition Point Sources Septic Loads 21 21

  22. Inputs BMP implementation Remote Sensing Crop acreage Crop yield Animal numbers Outputs BMP implementation on phase 5 scale Land use Crop Uptake Fertilizer Manure Sample Input and Output Parameters • BMP effects on land use • Tillage Type • Plant and harvest dates • Nutrient application by crop type • Animal manure nutrient content

  23. Automated Calibration • Ensures even treatment across jurisdictions • Fully documented calibration strategy • Repeatable • Makes Calibration Feasible • Enables uncertainty analysis 23

  24. RiverReach Where do we calibrate? Reasonable values of sediment, nitrogen, and phosphorus Observations of flow, sediment, nitrogen, and phosphorus

  25. Phase 5 River Segments and Calibration Stations Flow: 292 Water Quality: 130

  26. Calibration Strategy • Match observations in rivers • Match properties and trends • Groundwater recession curve • Crop uptake of nitrogen • Match literature and other models • Reasonable rates of nutrient export • USGS estimator and sparrow empirical models

  27. Calibration Process Single-processor time Hydrology Land parameters River data 1 week Temperature Land parameters River parameters River data Land Sediment Land parameters Land targets 1 week Land Nutrients Land parameters Land targets 1 week River Water Quality River parameters River targets 2 weeks

  28. Open-Source Model Transferability • Entire model available on web • Input data • Modified HSPF • Phase 5 system • Already in Use • Community model in Climate Change Study • Community model at ICPRB • Phase 5 output in Potomac PCB TMDL • Phase 5 information in MDE TMDLs • Phase 5 information in USGS Watershed Study • USGS Shenandoah Models • Phase 5 output in Academic studies • UNC / Baltimore LTER study

  29. WSM Uses:Divide Load into contributing areas and sources Ultimate Source Land Use Source

  30. WSM Uses:Track Implementation Progress from different sources over time Agriculture

  31. Nitrogen Loads Delivered to the Chesapeake Bay By Jurisdiction Point source loads reflect measured discharges while nonpoint source loads are based on an average-hydrology year 333.9 289.9 281.1 277.7 275.1 270.2 266.3 262.9 261.9 260.7 184.4 183.1 175 31

  32. WSM Uses:Determine Effective Practices From the Chesapeake Bay Commission Report: Cost-Effective Strategies for the Bay December, 2004

  33. WSM Uses:Estimate annual loads below monitoring stations Roughly 25% of the total load is unmonitored

  34. WSM Uses:Allocating Nitrogen-Phosphorus-Sediment loads ...then by 20 major tributary basins by jurisdiction …then by 44 state-defined tributary strategy subbasins By 9 major river basins Watershed States Responsibility Watershed States Responsibility Watershed Partners Responsibility

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