Simulation of Runoff Losses From Watersheds Managed Under Diverse Land Management.

Hydrologic simulation models are useful in simulating the effects of different land uses on runoff and sediment losses from watersheds. This study was conducted for the Mill Creek Watershed, a subwatershed located within the Muskingum River Watershed in Coshocton County, Ohio. Mill Creek flows south discharging into the Walhonding River near the city of Coshocton, and this watershed drains approximately 70.4 square kilometers. The mainstem stretches a total length of 26.2 kilometers and is a steeply graded stream with an average descent of 4.2 m per kilometer. Mill Creek is largely cultivated (61%) and upland forest (39%) and has been subject to the affects of extensive farming and forestry over a period of more than 100 years. These impacts have made significant changes to the stream habitat, adjacent floodplains and riparian corridors, erosion and sedimentation levels and the quantity and quality of storm water runoff. Thus, the objectives of this study are to simulate runoff losses from Mill Creek Watershed and simulate best management practices to reduce the runoff losses from the watershed outlet. The long-term scenario analysis to implement the best management practices (BMPs) for reducing the runoff was simulated by Soil and Water Assessment Tool (SWAT) model. To date, a SWAT model of baseline conditions has been developed and calibrated for 1982-2010. The Nash-Sutcliffe efficiency (NSE), Pbias and R² values for calibration of monthly flows are 0.66, 0.54, and 0.66. Results from this study will show that installing alternative conservation practices simulated from SWAT model will be helpful in reducing the runoff, and improve the water quality.