Document Type : Research Paper
Authors
1 Assistant Professor, Faculty of Natural Resources, Urmia University, Iran
2 MSc Graduated, Faculty of Natural Resources, Urmia University, Iran
3 Associate Professor, Faculty of Natural Resources, Urmia University, Iran
4 Associate Professor, Faculty of Technology of Natural Resources, Mohaghegh Ardabili University, Iran
Abstract
Soil erosion from socio-economic and environmental aspects of view is important, and decision making for applying proper watershed management practices is essential to control or mitigate it. In recent years, the Soil and Water Assessment Tool (SWAT) model as widely-used tool have been applied to simulate flow discharge, sediment yield, and to evaluate watershed management practices in reducing runoff and sediment yield. This research aims to simulate monthly flow discharge and sediment yield using the SWAT model to identify critical sub-watersheds yielding specific sediment in Nazlochai watershed, located in the West of the Urmia Lake. In this study, a monthly stream flow and sediment discharges data series were used during 1997–2007 for model calibration and 1993–96 for validation. To evaluate model efficiency, some statistical criteria consist of the determination coefficient (R2), the Root Mean Square Error (RMSE), the Nash-Sutcliffe Efficiency (NSE), and the Mean Bias Error (MBE) was used. For the sake of model calibration, validation and uncertainty analysis, the SUFI2 program was utilized, which it is included in the SWAT-CUP software as a public domain program. The NSE values for simulating monthly flow discharge in calibration and validation periods were 0.7 and 0.85, while for monthly sediment discharge simulation were 0.65 and 0.75, respectively. The evaluation criteria showed that the model is satisfactory capable to predict monthly flow and sediment discharges. To identify critical areas, the calibrated model was applied in validation period. Out of 17 sub-watersheds, sub-watersheds 17, 13, and 16 with the highest amounts of Specific Sediment Yield (SPY) in ton/ha/year were identified as critical sub-watersheds and were prioritized respectively for soil conservation and management purposes.
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