Spatio-temporal analysis of water storage variation and temporal correlations in the East Africa lake basins

Abstract

Study region: East Africa (EA), lake basins (Tana, Abaya-Chamo, Turkana, Victoria, and Tanganyika), 6472,404 km2 of total area. Study focus: Total water storage change (TWSC) exposes serious challenges in sustainable water resources management and ecosystem sustenance. While TWS changes have been increasingly studied based on Gravity Recovery and Climate Experiment (GRACE) derived TWS dataset, spatio-temporal changes in TWS and the driving factors remain unexplored. Herein, Mann–Kendall test, Theil-Sen's slope estimator, empirical orthogonal functions (EOFs), component contribution ratio (CCR), and Soil and Water Assessment Tool (SWAT) models were employed. We found a slight spatial fluctuation of TWS, and groundwater could affect TWS variability in the EA region. New hydrological insights: High annual TWSC was observed in the southwestern and northern regions, reaching values of 220 and − 100 mm/yr, respectively. Among lake basins, the maximum and minimum TWSC values attained 97.5 ± 28.2 mm/yr and 24.8 ± 7.7 mm/yr, in Victoria and Tana basins, respectively. The regional level groundwater contribution was about 42%, while 48%, 53%, and 46% were in Abaya-Chamo, Turkana, and Victoria basins, respectively. However, surface runoff contribution was 52% and 35% in Tana and Tanganyika basins, respectively. The seasonal TWS changes show substantial linkage with the lake basins' seasonal precipitation distribution. Our findings highlight the driving factors of TWS variability, which could help guiding water management policies, and promote satellite remote sensing datasets.

Keywords

• GRACE
• East Africa lake basins
• Total water storage
• Component contribution ratio
• SWAT model