Land use land cover change as a casual factor for climate variability and trends in the Bilate Watershed, Ethiopia

Abstract

Climate change and land use dynamics are critical issues facing many regions worldwide, particularly in developing countries. This study examines the spatiotemporal changes in land use and land cover (LULC) and their impact on climate variability in the Bilate Watershed, Ethiopia, from 1994 to 2024. Utilizing multispectral satellite imagery from Landsat 5, 7, and 8, along with meteorological data from five weather stations, LULC classification was performed using the Random Forest algorithm on the Google Earth Engine platform. To analyze climatic variability and trends, the Mann–Kendall trend test, the Standardized Precipitation Index (SPI), and the Standardized Temperature Index (STI) were employed. The findings indicate a significant decline in forest cover, with an accelerated annual loss of approximately 4681.2 hectares between 2014 and 2024. Concurrently, agricultural land expanded by about 1141 hectares annually, and urban areas grew by 24.3 hectares per year in recent years. Seasonal mean rainfall variation showed significant declines in the upper catchment, with Bega (p = 0.004, Sen’s slope = − 3.819 mm), Belg (p = 0.006, Sen’s slope = − 7.972 mm), and Kiremt (p = 0.005, Sen’s slope = − 7.117 mm), while the lower catchment experienced a notable increase during the Belg season (p = 0.025, Sen’s slope = 6.424 mm), highlighting uneven water availability across the watershed. Furthermore, pronounced warming trends were observed in the upper catchment (Bega: p = 0.002, Sen’s slope = 0.029; Belg: p = 0.001, Sen’s slope = 0.030; Kiremt: p = 0.004, Sen’s slope = 0.018), with moderate warming noted in the middle catchment during the Kiremt season (p = 0.020, Sen’s slope = 0.016). These LULC changes have significantly impacted climate variability, emphasizing the critical influence of human activities on regional climate dynamics. This study underscores the urgent need for sustainable land management and conservation strategies to mitigate the challenges posed by deforestation, urbanization, and agricultural expansion.