ESTIMATION OF SEDIMENT YIELD AND EFFECTIVENESS OF LEVEL STONE BUNDS TO REDUCE SEDIMENT LOSS: IN GUMARA-MAKSEGNIT WATERSHED, NILE BASIN, ETHIOPIA

Abstract

The study was conducted in Gumara-Maksegnit watershed and it’s sub-catchments to estimate event-based sediment yield and to evaluate the effectiveness of level stone bunds based on sediment loss reduction. Modified Universal Soil Loss Equation (MUSLE) was used for estimation of sediment yield. The model input parameters were collected from different sources and these are discretized and preprocessed with the help of various suitable software and tools. Finally, all six model factors were combined together using the raster calculator in map algebra to estimate the sediment yields of the study watersheds. The event-based mean observed and model estimated sediment yields were (0.5581, 0.4031 ton ha-1 ) for Gumara-Maksegnit watershed, (0.5125, 0.4194 ton ha-1 ) for treated sub-catchment and (1.0694, 1.0150 ton ha-1 ) for untreated sub-catchments respectively. The sediment losses between treated and untreated sub-catchments were highly significantly different when the sediment loss reduced by 58.8% as a result of level stone bund interventions. However, the observed and estimated sediment losses are not significantly different within a watershed. Hence, the model was well performed to estimate sediment yield in the study area with R2 (0.62, 0.72 and 0.7) and NSE (0.53, 0.71 and 0.34) for treated, untreated and Gumara-Maksegnit watershed respectively. Hence, the result showed that the Modified Universal Soil Loss Equation (MUSLE) model was well suited for reliable applications of sediment yield estimation in the study area as well as similar agroecologies