Storm event flow and sediment simulations in a central New York watershed: Model testing and parameter analyses

In this study, we tested the prediction ability of the Dynamic Watershed Simulation Model (DWSM), an event-based watershed model, on an agricultural watershed in central New York State and its ability for use as a management tool. Using five different storm events, we identified a set of key parameters that allowed DWSM to best predict hydro-graphs and sedigraphs of the events for both the curve number and interception-infiltration rainfall-runoff methods. Subsequent sensitivity analyses revealed that modeling outcomes (i.e., peak water and sediment discharges, total event runoff volume, and event sediment yield) were most sensitive for the first method to CNAF, a factor adjusting runoff CN values, and most sensitive for the second method to HYCND and VOG, parameters reflecting soil hydraulic conductivity and interception loss. These analyses led to benchmark values of the key parameters and empirical relationships between precipitation and the three most sensitive parameters, which were validated using two additional storm events. Based on these results, we propose a general modeling procedure that can best predict event hydrographs and sedigraphs for watershed management planning.