Description of WMS

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Description of WMS

• Watershed Modeling System

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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

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Digital Terrain Models

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

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Digital Terrain Models DEM
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Digital Terrain Models TIN
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Digital Terrain Models GIS Data
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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

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Digital Terrain Model Uses

• Land Use and Soil Type

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Digital Terrain Model Uses

• Composite Curve Number

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Digital Terrain Model Uses

• Time of Concentration

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Calculators Detention Basins

• Detention Basin Analysis/Design
• EAV Curves form a TIN
• Route hydrographs through basin

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Calculators Channels

• Cut cross sections from DEM or TIN
• Examine hydraulic properties
• Export for use in other applications (i.e. RAS)

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Calculators Channels

• Delineate Flood Plain

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Calculators Channels

• Hydraulic calculations

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Calculators Culverts

• HY8 culvert analysis program included in WMS

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Calculators Curb and Gutter Flow

• 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.

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Hydrologic Models

• Provides graphical interfaces and actual
  following models
• HEC-1
• HSPF
• TR-20 and TR-55
• Rational Method
• NFF

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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

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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.

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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

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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

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Hydrologic Models Rational Method

• Q CiA (Im 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
• Mannings n, basin length, slope
• Output is peak flow of basin

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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.

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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

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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.

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Summary

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