Temporal Dynamics of Surface Water Extent in Lake Haramaya, Ethiopia Using Multi-Sensor Satellite Data (1990–2024)

This study examines the significant fluctuations in the surface area of Lake Haramaya in eastern Ethiopia from 1990 to 2024, utilizing time series analysis of Multi-Spectral (MS, Landsat) and Synthetic Aperture Radar (SAR, Sentinel) satellite imagery. Annual water extent was mapped using the Modified Normalized Difference Water Index (MNDWI) applied to MS data and complementary SAR-based water detection. The analysis reveals a clear trajectory of severe decline, with the lake's surface area shrinking by 87.5% from 3.77 km² in 1990 to a critical low of 0.47 km² by 2020, culminating in near-complete desiccation around 2005 and again in 2017. A weak statistical correlation between lake extent and rainfall (r ≈ −0.27) indicates that climatic variability was not the primary driver of this collapse. Instead, the shrinkage is strongly attributed to anthropogenic pressures, including unregulated water extraction for irrigation, particularly for khat cultivation, urban water supply, domestic use, and watershed erosion. Remarkably, a significant resurgence was observed after 2020, with the lake recovering to 2.73 km² by 2024, primarily due to concerted catchment rehabilitation and soil and water conservation efforts. In particular, the Participatory Integrated Watershed of Haramaya Lake Development (PILHWSD) program, led by local institutions and communities, has played a central role in reducing runoff, enhancing recharge, and improving watershed conditions. The findings underscore the critical impact of human activity on fragile aquatic ecosystems and highlight the potential for recovery through integrated watershed management and sustainable water resource policies.