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Description of WMS

Description of WMS. Watershed Modeling System . What Model Does. Integrates GIS and hydrologic models Uses digital terrain data to define watershed and sub basin characteristics Provides interface for hydrologic models widely used in industry

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Description of WMS

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  1. Description of WMS Watershed Modeling System

  2. What Model Does • Integrates GIS and hydrologic models • Uses digital terrain data to define watershed and sub basin characteristics • Provides interface for hydrologic models widely used in industry • Provides useful calculators for hydrologists and engineers

  3. Digital Terrain Models • Input • Three primary sources for model development • Geographic Information Systems (GIS) Data • Digital Elevation Models (DEMs) • Triangulated Irregular Networks (TINs)

  4. Digital Terrain Models: DEM

  5. Digital Terrain Models: TIN

  6. Digital Terrain Models: GIS Data

  7. Digital Terrain Models • Output: • Delineates basin boundaries • Tool for obtaining basin characteristics such as: • Land Use • Lag Times • Time Area Curves • Curve Numbers • Areas • Slopes • Runoff Distances

  8. Digital Terrain Model: Uses Land Use and Soil Type

  9. Digital Terrain Model: Uses • Composite Curve Number

  10. Digital Terrain Model: Uses • Time of Concentration

  11. Detention Basin Analysis/Design EAV Curves form a TIN Route hydrographs through basin Calculators: Detention Basins

  12. “Cut” cross sections from DEM or TIN Examine hydraulic properties Export for use in other applications (i.e. RAS) Calculators: Channels

  13. Delineate Flood Plain Calculators: Channels

  14. Hydraulic calculations Calculators: Channels

  15. HY8 culvert analysis program included in WMS Calculators: Culverts

  16. The FHWA HEC22 equations are built into WMS and can be used to examine flow across storm drain inlets for a variety of curb and gutter openings. Calculators: Curb and Gutter Flow

  17. Hydrologic Models • Provides graphical interfaces and actual following models : • HEC-1 • HSPF • TR-20 and TR-55 • Rational Method • NFF

  18. Hydrologic Models: HEC-1 • Description • Flood hydrograph program that models the rainfall-runoff process • Input: • Basin model • Many characteristics obtained from digital terrain model • Precipitation model • Control specifications • Output • Hydrographs at any hydrologic feature

  19. Hydrologic Models: HSPF • Description: • Model developed by the USGS • Simulates hydrologic and water quality processes on land surfaces, streams and impoundments • Generally used to assess the effects of land-use change, reservoir operations, point or nonpoint source treatment alternatives, flow diversions, etc.

  20. Hydrologic Models: HSPF • Input: • Time history of rainfall, temperature and solar radiation, land use characteristics • Output: • Time history of the quantity and quality of runoff from an urban or agricultural watershed. • Flow rates, sediment loads, nutrient and pesticide concentrations

  21. Hydrologic Models: TR-55, TR-20 • Description: • TR-55 and TR-20 both model the rainfall runoff process with TR-55 being used especially for small, urban or urbanizing watersheds. • Input: • Land characteristics to calculate curve numbers • Rainfall model • Basin model • Output: • Hydrographs

  22. Hydrologic Models: Rational Method • Q = CiA (I’m assuming we are all familiar with this) • WMS provides a rational method calculator • Generates IDF curves for eastern US • FHA Kinematic wave equation can estimate Tc of basin given: • Manning’s n, basin length, slope • Output is peak flow of basin

  23. Hydrologic Models: NFF • Description: • Developed by FEMA, FHA, and USGS • Uses regression equations to estimate T-year flood-peak discharges for rural and urban watersheds • Most of the equations are a function of basin area, stream length, and other parameters easily computed from digital terrain models.

  24. Hydrologic Models: NFF • Input: • Basin characteristics • Basin location (State and region) • Output • Peak flood flows for basin • Typical flood hydrographs for given T-year peak discharge

  25. More on WMS • Contains Hydrology for LA County and Maricopa County • Hydrographs and other data produced in WMS can be exported for use in standard spreadsheet software • Free extension to Arcview GIS program “WMS Hydro” • This extension can be used to prepare land use, soil, or elevation data for use by WMS and it can also be used to manage/view results produced by WMS.

  26. Summary • Powerful Model • Integrates GIS technology with hydrologic models • Useful calculators • According to Ryan, fairly easy to use

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