Western Washington Hydrology Model Version 3

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Western Washington Hydrology ModelVersion 3

• Vancouver, WA, Workshop
• October 17, 2007 AM

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Western Washington Hydrology ModelVersion 3

• Instructors
• Doug Beyerlein, P.E.
• Joe Brascher
• Clear Creek Solutions, Inc.
• www.clearcreeksolutions.com

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Clear Creek Solutions Hydrology Expertise
Clear Creek Solutions, Inc., provides complete
range of hydrologic and stormwater modeling
services.

• Clear Creek specializes in continuous simulation
  hydrologic modeling.
• We have 30 years of experience modeling complex
  hydrologic and stormwater problems.
• We created WWHM3 for Washington State Department
  of Ecology and are adapting it to model San
  Francisco Bay Area watersheds and facilities.
• We teach WWHM and HSPF workshops.

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WWHM Introduction

• Developed for the State of Washington Department
  of Ecology.
• Project Manager Dr. Foroozan Labib
• Department of Ecology
• PO Box 47600
• Olympia, WA 98504-7600
• [phone]
• email flab461_at_ecy.wa.gov

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WWHM Introduction
Developed for the 19 counties of western
Washington. Part of Ecologys Stormwater
Management Manual

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WWHM Introduction
WWHM3 Standard is available free from the
Washington State Department of Ecology web site
http//www.ecy.wa.gov/programs/wq/stormwater/

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WWHM Background and Theory

• Ecologys Stormwater Management Manual
• Specifies a flow duration standard
• Requires the use of Western Washington
  Hydrology Model (WWHM) or equivalent

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WWHM Background and Theory

• Flow duration standard based on erosive flows.
• Erosive flow range ½ of 2-year to 50-year flow.

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WWHM Background and Theory Flow Duration
Analysis Percent of time the flow exceeds a
specific value.

• Requires continuous simulation hydrology to
  compute flow duration.

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WWHM Background and Theory

• Continuous simulation hydrology models the entire
  hydrologic cycle for multiple years.
• Stormwater runoff surface runoff interflow.

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WWHM Capabilities

• WWHM uses continuous simulation hydrology to
  compute stormwater runoff for both predevelopment
  and post-development conditions.
• Predevelopment Post-development

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WWHM Capabilities

• WWHM continuous simulation computations from
  HSPF (included in WWHM software).
• HSPF runs in the background with calibrated
  parameter values and local meteorological data.
• HSPF sponsored and funded by EPA and USGS.

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How WWHM/HSPF works

• Drainage areas are divided into pervious land
  segments based on soil, vegetation, and land
  slope and impervious land segments.
• Pervious and impervious segments are linked to
  conveyance pathways (pipes, ditches, ponds,
  streams, rivers, lakes, etc.)
• Historic rainfall and evaporation are used as
  input.

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How WWHM/HSPF works

• The entire water cycle is modeled on an hourly
  or shorter time step for multiple years.
• The model computes changes in soil moisture,
  evapotranspiration, and runoff every time step.
• Three types of runoff
• surface runoff
• interflow
• groundwater/base flow

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How WWHM works

• Calibrated parameter values are built into WWHM
  (different calibrated parameter values are used
  for different climatic regions).
• Local precipitation and evaporation data are
  included in WWHM.

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How WWHM works

• User locates project on county map, inputs pre-
  and post-development land use, and proposed
  mitigation measure(s).
• Predevelopment and mitigated flows are compared
  at Point of Compliance (POC).
• Mitigated flows are not allowed to exceed flow
  duration standards.

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How WWHM works

• User outputs report file and project file.
• Output files can be submitted to the permitting
  agency for approval.
• Permitting agency can load project file and
  rerun analysis, if needed.
• Report file summarizes input data and output
  results.

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How WWHM works

• Guidance/help is provided by
• User Manual
• Training Workshops
• CCS Project Book
• Tech Support
• Go to www.clearcreeksolutions.com for more
  details.

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WWHM Version 3

• Goal give the user greater flexibility and
  options
• High groundwater element
• Lateral flow between basins
• More elements
• More output options
• New LID options

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WWHM Version 3

• Version 3 projects have no drainage area size
  limitations entire watersheds can be modeled.
• Version 3 can be customized to local
  jurisdictions (e.g., City of Bellingham, City of
  Seattle).

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WWHM3 Standard

• 14 elements
• basin
• trapezoidal pond
• tank
• lateral pervious basin (NEW)
• high groundwater/wetland (NEW)
• vault
• open channel (NEW)
• time series (NEW)
• lateral impervious basin (NEW)
• gravel trench bed (NEW)
• sand filter
• flow splitter (IMPROVED)
• irregular-shaped pond
• stage-storage-discharge table

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WWHM3 PRO Basic

• WWHM3 Standard plus
• user selected time step
  (5 minutes to one hour)
• tagged flow routing
• additional elements
• culverts
• green/vegetated/eco-roofs
• bioretention swales/rain gardens

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WWHM3 PRO GIS

• WWHM3 PRO Basic plus
• Map Explorer

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WWHM3 PRO GIS

• WWHM3 PRO Basic plus
• GIS Import

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WWHM3 PRO SWMM

• WWHM3 PRO Basic plus
• SWMM Routing

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WWHM3 PRO Complete

• WWHM3 PRO Basic plus
• SWMM
• GIS

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WWHM3 LID Modeling

• Green/vegetated/eco-roof
• Bioretention swales/rain gardens
• Porous pavement

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WWHM3 LID Modeling
Green/vegetated/eco-roof

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WWHM Green Roof Modeling

• Study performed for Seattle Public Utilities
• Green roof modeled Portland Hamilton Building
• Data provided by Portland BES

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WWHM Rain Garden Modeling

• Seattle Bioretention Swales

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WWHM Rain Garden Modeling
Weir and vertical orifice outlet

Native Soil
Amended Soil (1-3 layers)
Native Soil
Underdrain (optional)
Native Soil
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WWHM Porous Pavement Modeling

• Currently represented by the gravel trench bed
  element.