| Abstract: |
The Chesapeake Bay Watershed Model has been used to simulate nutrient and sediment loads delivered to the Bay for more than two decades. Over time, the Model has increased in complexity commensurate with the management challenges in Chesapeake restoration. The current development, Phase 5 Community Watershed Model, is a new generation of the watershed model in response to the needs of developing Chesapeake Bay TMDL as well as supporting small scale local TMDLs. The Phase 5 Model simulates 308 land segments, 25 land uses, 930 rivers, and 45,000 land use/river connections over a 22-year period (1984-2005).
The Phase 5 Model enhances the existing HSPF model structure with a complementary software system to address unique spatial and temporal scale issues inherent in a large-scale watershed modeling. The software system, consisting of preprocessors, an External Transfer Module, and postprocessors, was devised to conveniently generate and update input files essential to model operations and to implement land use and management changes over time. An automatic model calibration method, designed to iteratively adjust model parameters based on the sensitivity of the parameters to particular model outputs, is utilized to calibrate the Phase 5 Model for hydrology, nutrients, and sediment. Through CCMP support, model code, preprocessors, postprocessors, a data library of model input data, and documentation are available for the Phase 5 applications at county or more local scales.
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