Using SWAT Model to Determine Runoff, Sediment Yield in Maroon-Dam Catchment

Soil erosion is a worldwide environmental problem that degrades soil productivity and water quality, causes sedimentation in reservoirs, and increases the probability of floods [1][2][3][4][5][6][7][8][9].Sediment transport rate is affected by hydrological as well as hydraulic characteristics.Since the former cannot be adequately taken into account quantitatively, a high degree of accuracy in sediment load computations cannot be expected [2][3].Watershed management programs frequently fail to reduce sediment yield because either the physical nature of the problem is not properly diagnosed or the economic and cultural conditions leading to accelerated erosion are not addressed and erosion control practices are abandoned as soon as government subsidies are removed (Gregory and Fan, 1998).Besides, the development of a comprehensive sediment yield model requires substantial funding, extensive time and expertise, which are often unavailable in developing countries [4][5][6].The soil and water assessment tool (SWAT) is a physically based, continuous time model, developed by Dr. Jeff Arnold for the USDA-ARS (Agricultural Research Service) (Arnold et al., 2001), mostly used to predict the impact of land management practices on water, sediment, and nutrient yields over Abstract: The Soil and water assessment tool (SWAT) model is a flexible, physically distributed model was developed as a river basin scale to quantify and predict runoff and transportation from watersheds and river basins.The semi-automated Sequential Uncertainty Fitting (SUFI2) calibration process built in SWAT calibration and uncertainty program (SWAT-CUP) were used to calibrate the model parameters using time series of flow and sediment load data of 1994 to 2002 and validated with the observed data from years 2002 to 2007.The performance of the model was evaluated using statistical and graphical methods to assess the capability of the model in simulating the runoff and sediment yield for the study area.The result showed relatively good fitness between measured and simulated discharge and sediment.The Nash Sutcliffe efficiency and R2 were nearly 70% for discharge and 76% for sediment load.Overall, simulation of runoff and sediment is satisfactory by using the SWAT model.