Hydrological Components and Sediment Yield Response to Land Use Land Cover Change in The Ajora-Woybo Watershed of Omo-Gibe Basin, Ethiopia

Abstract

Understanding how watersheds respond to ecological changes and how LULC alteration affects watershed hydrology is crucial for water and soil resource management. LULC changes in the Ajora-Woybo watershed, Ethiopia, have momentously affected the water and soil resources. The researchers aimed to see how LULC changes affect hydrological components (HCs) and sediment yield (SED) in the watershed, both historically and in the future. The Soil and Water Assessment Tool (SWAT2012) and Partial Least Squares Regression (PLSR) models were used to investigate the contribution of each of the LULC classes to achieve the goal. The findings revealed a continual growth of cultivated land, built-up areas, and bare land, and a retreat of shrub land and forest land during the 2000 to 2020 periods, which is expected to continue in the 2035 and 2050 periods. Changes in LULC that happened over the historical era increased yearly surface runoff (23.5%), water yield (5.7%), and sediment yield (23.5%). On the other hand, the observed modifications have reduced lateral flow (12.8%) and groundwater flow (10.9%). Except for the 2020 LULC period, evapotranspiration decreased during the studied years. The future impacts of LULC states are predicted to increase in line with the historical trend. The PLSR results showed that cultivated land and built-up areas had a positive association with surface runoff and sediment yield, but shrub land and forest land had a negative correlation. This highlights the importance of controlling the LULC change as soon as possible to maintain long-term watershed stability.