Evaluating the Impact of Land Use Changes on Flooding and Flood Runoff in Amuqin Drainage Basin

The progress in flood estimation techniques has enabled us to use rainfall-runoff models to evaluate the hydrographic properties of the flood in watersheds, thus lowering the risks of flooding. Accordingly, this study aimed to determine the peak flood discharge for Amuqin to reveal the impact of land use changes on peak flood discharge using a WMS model. Amuqin area stretches across approximately 78 km2 of land. The Curve Number (CN) of the basin was found by integrating land use maps with soil hydrologic group (B, C, D) obtained from analyzing Landsat 8 Images in IDRISI32 and overlaying the maps in ArcGIS and were estimated at 76.4 and 78.7 for 2000 and 2015, respectively. The model calibration (RE= 7.17، RMSE = 0.44) and validation results (RE%= 2.51, RMSE= 0.0042) with rainfall-runoff phenomena in the area, suggested consistency with observations. Given the high sensitivity of this method to rainfall distribution, an analysis of rainfall across the region is required to obtain reliable results. Further, the curve number of the basin showed a 3% increase between 2000 and 2015 due to the reduced quality of the rangelands and the change to agricultural land use in areas of the basin most prone to flooding and erosion, which increases the peak flood discharge by 22, 26 and 25.5% for return periods of 25,50 and 100 years, respectively. The management of land use seems in order to prevent future increases in the catchment CN.