Modeling Sediment Yield with Current and Projected Climatic Scenarios in Andit Tid Watershed, Central Highland of Ethiopia

Abstract

Our ability to engage in long-term land management solutions that will benefit both land and water users is made possible by our understanding of how climate change affects sediment yield. This study aimed to determine the spatiotemporal distribution of sediment yield in the Andit Tid watershed as well as simulate sediment yield under existing and anticipated climate scenarios. SWAT and Arc GIS 10.5 software were used to estimate and map the spatial distribution of sediment yield. The annual average estimated sediment yield of the watershed was found to be 17.9 t ha-1 yr-1. The R2 was found to be 0.62 and 0.72 during calibration and validation of sediment yield. The projected average sediment yield up to 2098 under the wettest scenario is 13.7 t ha-1 in RCP 4.5 and 16.1 t ha-1 in RCP 8.5, respectively. It was discovered that, in comparison to the current average sediment, the near future (2022–2060) sediment was equal to it in RCP 4.5 and decreased by 41% in RCP 8.5, whereas the far future (2061–2098) sediment grew by 20.4% in RCP 8.5 and decreased by 35% in RCP 4.5. Out of the projected 76 years, 21 and 23 years showed positive deviations from the mean of the existing sediment yield under RCP 4.5 and 8.5, respectively. While in the driest scenario, the projected sediment yield was lower than the current rate, which was about 4 t ha-1 in both RCPs. In both current and future climate scenarios, the northeastern, eastern, and western regions were contributing to the higher sediment yield in the watershed. Most of these watershed hotspot regions were situated on farmed land with a slope of more than twenty percent and active gullies. When developing and executing management solutions in the areas that are severely impacted, the watershed community and decision-makers are recommended to make use of the spatial distribution map. It is also necessary to take steps to lessen the likelihood that the emission scenarios that result in RCP 8.5 will occur.