Department of Geography and Environmental Studies, Wachemo University, Hossana, Central Ethiopia, 667, Ethiopia.
Department of Geography, School of Earth sciences, Central University of Tamil Nadu, Thiruvarur, India.
Environ Monit Assess. 2024 Nov 25;196(12):1250. doi: 10.1007/s10661-024-13435-y.
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.
气候变化和土地利用动态是全球许多地区，特别是发展中国家面临的关键问题。本研究考察了 1994 年至 2024 年期间埃塞俄比亚 Bilate 流域土地利用和土地覆盖（LULC）的时空变化及其对气候变率的影响。利用 Landsat 5、7 和 8 的多光谱卫星图像以及来自五个气象站的气象数据，在 Google Earth Engine 平台上使用随机森林算法进行 LULC 分类。为了分析气候变率和趋势，使用了 Mann-Kendall 趋势检验、标准化降水指数（SPI）和标准化温度指数（STI）。研究结果表明，森林覆盖面积显著减少，2014 年至 2024 年期间，每年约有 4681.2 公顷的森林以加速的速度消失。与此同时，农业用地每年增加约 1141 公顷，近年来城市面积每年增长 24.3 公顷。季节性平均降雨量变化表明，在上游集水区，Bega（p=0.004，Sen 的斜率=-3.819mm）、Belg（p=0.006，Sen 的斜率=-7.972mm）和 Kiremt（p=0.005，Sen 的斜率=-7.117mm）的降雨量显著减少，而在下游集水区 Belg 季节的降雨量显著增加（p=0.025，Sen 的斜率=6.424mm），这突显了流域内水资源分布不均。此外，在上游集水区观察到明显的变暖趋势（Bega：p=0.002，Sen 的斜率=0.029；Belg：p=0.001，Sen 的斜率=0.030；Kiremt：p=0.004，Sen 的斜率=0.018），而在 Kiremt 季节中游集水区的变暖程度中等（p=0.020，Sen 的斜率=0.016）。这些土地利用变化显著影响了气候变率，强调了人类活动对区域气候动态的关键影响。本研究强调了可持续土地管理和保护战略的迫切需要，以减轻森林砍伐、城市化和农业扩张带来的挑战。
