Poster: Suburban Watershed Modeling: Using Soil Moisture Distribution and Routing to Asses the Impact of Suburban Development.
Zachary Easton Tammo Steenhuis A.Martin Petrovic

In regions with steep slopes, underlain by shallow bedrock, runoff lossescan be significant. Suburban areas can have significant areas of low or impermeable surfaces, which prevent runoff from infiltrating the soil, and increases soil moisture levels in the surrounding soils. This can increase runoff, particularly in areas with low hydraulic conductivity or shallow soils, i.e. lower hill slopes. The Soil Moisture Distribution and Routing Model (SMDR) was used to model the soil moisture distribution and the ensuing effect on stream flow in a sloped suburban watershed. Results indicate that impervious areas associated with suburban development will increase soil moisture levels, saturated areas and subsequently increase runoff losses, causing a rapid stream response to precipitation. SMDR was able to adequately capture the dynamics of stream flow (Nash Sutcliffe efficiency E=0.74), however, snowmelt stream flow was captured less well (E=0.35). The model predicted the soil moisture distribution well for less developed areas with a slight over estimate, and less well for more heavily developed areas with an underestimate. However, reducing the soil storage function resulted in a much better fit to the observed data. That is, in areas of heavy development the field capacity was reduced a representative amount to account for the effect of foundations, roadways, and parking lots. Model efficiencies for individual precipitation events ranged from E=0.09 to E=0.86, with larger events being captured better. Results indicate that SMDR can be a valuable tool in assessing the impact of suburban areas on hydrology and water quality.


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