Sediment management modelling in Blue Nile Basin using SWAT model

Abstract

Abstract. Soil erosion/sedimentation is a colossal problem that has menaced water resources development in the Nile, particularly in Eastern Nile (Ethiopia, Sudan and Egypt). An insight into soil erosion/sedimentation mechanism and mitigation methods plays an indispensable role for the sustainable water resources development in the region. This paper presents a daily sediment yield simulation in the Upper Blue Nile under different Best Management Practices (BMPs) scenarios. The scenarios were baseline (existing condition), Buffer strips, stone bund (parallel terrace), and reforestation. The Soil and Water Assessment Tool (SWAT) was used to model soil erosion, identify soil erosion prone areas and assess the impact of BMPs on sediment reduction. The study found satisfactory agreement between daily observed and simulated sediment concentration with Nash-Sutcliffe efficiency (NSE)=0.88, percent bias (PBIAS)=−0.05%, and ratio of the root mean square error to the standard deviation of measured data (RSR)=0.35 for calibration and NSE=0.83, RSR=0.61 and PBIAS=−11% for validation. The sediment yield for baseline scenario was 117×106 t yr−1. The buffer-strips, stone-bund and reforestation reduced the sediment yield at outlet of the Upper Blue Nile basin by 44%, 41% and 11%, respectively. The sediment reduction at subbasins outlets varied from 29% to 68% by buffer strip, 9% to 69% by stone-bund and 46% to 77% by reforestation. This study clearly demonstrates the efficacy of catchment management intervention (BMPs) for sustainable water resources development in the Eastern Nile basin.