Application of SWAT for sediment yield estimation in a mountainous agricultural basin

The advanced SWAT (soil and water assessment tool) model is based on hydrologic process and needs to be calibrated and validated prior to application. This paper presents a case study conducted in Chaohe river upstream to verify the applicability of SWAT for predicting sediment yields in a semiarid mountainous basin. Utilizing the gage records, the SWAT was deeply explored in the study area. The monthly measured runoff and sediment yields at Dage gage during the period 1985-1987 was used to calibrate the model while data from 1988 to 1990 was used for model validation. First, runoff calibration and validation were performed, and the resulted monthly Nash-Sutcliffe efficiency coefficient (E^NS) and R² were 0.81 and 0.93 for calibration period, respectively, 0.51 and 0.78 for validation period. Then, the sediment calibration and validation were carried out, and the E^NS and R² for calibration and validation were both above 0.70 and 0.75, respectively. Finally, based on the annual sediment yields estimated by the calibrated model, the annual soil loads map was generated and the critical soil loss subbasins dominated by agricultural land were identified. This study revealed that the SWAT could be applied in a rugged mountainous region for erosion control and watershed management.