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Objectives

Areas of Application

Unlike many statistical-based models, WAM is a physically-based model that simulates the hydrology and water quality responses within a watershed based on detailed characterization data of the physical processes taking place. WAM has the ability to model extremely complex watersheds including agricultural/urban/native land uses, natural and channelized stream networks, looped flow networks, multiple hydraulic structures within the stream/canal system, springshed groundwater systems, and tidally influenced boundary conditions. In addition, shorelines can be assigned as reaches for a more precise delivery of water and constituents to large rivers, lakes and estuaries. Closed basins and depressions are handled routinely. Various options or extensions are also available for implementation depending on application area. These extensions include, at this time, an indexing sub-model for bacteria and toxins, linkage to Water Quality Analysis Simulation Program (WASP) and the BathTub model, which enables the simulation of dissolved oxygen and chlorophyll-a, and to identify wildlife diversity within wetlands. The developers of WAM have left the source code as transparent as possible to allow for further customizations as needed by specific users. This will increase the use and broaden the scope of WAM for a given watershed.

Objectives

  • Simulate/analyze flows and loads of constituents for existing:

    • Land uses

    • Land management practices

    • Soils

  • Develop nutrient strategies for flow and water quality improvements to:

    • Identify existing sources by land use and region

    • Identify loads to streams, reservoirs, and lakes

  • Analyze the environmental impacts on streams, reservoirs, and lakes for abatement scenarios by modifying and/or creating:

    • Land uses

    • Management (BMPs)

    • Regional Stormwater Treatment Areas, such as (STAs/RASTAs)

Capabilities

  • Calculate surface and ground water flow and associated nutrient constituents from every land source grid cell within the watershed on a daily basis, and then route this water and associated constituents to the nearest stream using unit hydrographs adjusted based on flow distance and gradient.

  • Influence of impervious surface runoff and onsite retention/detention systems are applied prior to routing to the nearest stream.

  • Flow within the stream network is calculated using a hydrodynamic and constituent transport model that runs on a variable time step

  • Resulting simulated flow and constituent concentrations can be reviewed and analyzed for every source cell and stream reach within the watershed.