Drivers and long-term variability of lake evaporation in East African Lakes

Study region Six East African lakes (Abaya, Chamo, Tana, Turkana, Victoria, and Tanganyika), located in one of the world’s most climate-sensitive tropical regions. Study focus Lake evaporation is a key component of regional water balance, yet lack of direct evaporation measurements and in situ observations continues to limit reliable regional assessments. This study evaluates long-term (1980–2024) evaporation dynamics and their climatic drivers by integrating bias-corrected ERA5-Land reanalysis, satellite and ground-based observations, and both process-based (WRF-Lake) and empirical (Priestley-Taylor) models. Long-term variability and potential breakpoints are identified using Bayesian change-point detection (BEAST), while ElasticNet regression quantifies the relative contributions of hydroclimatic drivers. New hydrological insights for the region Regional lake evaporation increased significantly at a rate of 1.7 ± 0.4 mm yr⁻¹ , with distinct temporal patterns among lakes. Shallow lakes (Abaya and Chamo) exhibited rapid responses to radiative and vapor pressure variations, while deep lakes (Victoria and Tanganyika) showed slower but persistent increases due to higher thermal inertia. In contrast, Lake Turkana displayed early declines followed by only marginal long-term increases. Attribution analysis identified vapor pressure gradient, wind speed, and downward shortwave radiation as dominant drivers, collectively explaining about 85% of the variance. These findings enhance understanding of lake-climate interactions and underscore the need to incorporate lake-specific processes into regional climate modeling and adaptive water management strategies.