Assessment of the Past and Future Land Use/Land Cover Changes on Ecosystem Services Values and its implication for effective water resource management in the Upper Awash sub-basin, Ethiopia

Understanding past and future land use/land cover (LULC) changes and their impacts on ecosystem service values (ESVs) is essential for effective natural resource management. This study analyzes historical LULC dynamics and models future scenario to assess their implications for water-related ecosystem services in the upstream Awash basin (USAB). Using remote sensing and GIS-based approaches, the study quantifies LULC changes over recent decades and projects the future through predictive modeling. The LULC dynamics were mapped using the supervised maximum likelihood image classification approach based on Landsat 5 TM-GLS 1984, Landsat 7 ETM-GLS 2000, and Landsat 8 2019 OLI-TIRS to model potential LULC in 2019 and 2038 using Landsat images from 1984, 2000, and 2019. The study's findings demonstrate the significant shifts in LULC between 1984 and 2019, with urbanization and agricultural growth serving as the primary causes. Between 1984 and 2019, urban area grew by 570.5%, agricultural by 62%, and forests by 88.7%. In the same year, there was a 68.6% decline in the area of shrub-land, a 65.5% decrease in the area of water, and a 57.7% decrease in the area of grassland. According to future projects, there will be a comparable decrease in agricultural land, forest land, grassland, and water bodies as urban areas (109%) and agricultural land (49%) continue to grow. The results showed that ESV decreased from US$ 739.51 million to US$ 338.97 million between 1984 and 2019, and it is predicted to drop to US$ 279.6 million in 2038. The shrub-land had the highest ESV, followed by the cultivated land. The change in ESV in the study USAB results in a net negative loss of US$400 between 1984 and 2019, and projected to drop to US$59 million between 1984 and 2038. This suggests that the ESV has decreased dramatically as results of the slight decreased in the amount of forest and shrub-land. The results indicate significant shifts in LULC, particularly urban expansion, deforestation, and agricultural intensification, leading to alterations in ecosystem functions. These changes affect key ecosystem services, including water regulation, water supply, gas and climate regulation and water purification, ultimately influencing water availability. The findings provide insight into how shifts in land cover influence water-related ecosystem services, and hydrological processes, ultimately guiding policymakers to prioritize ecological conservation for effective water resource management.