Groundwater/surface-water interactions on deeply weathered surfaces of low relief: evidence from Lakes Victoria and Kyoga, Uganda

摘要: Little is known of the interactions between groundwater and surface water on deeply weathered landscapes low relief in Great Lakes Region Africa (GLRA). The role sustaining surface-water levels during periods absent rainfall disputed commonly excluded from estimations balances. Triangulated piezometers installed beside lake gauging stations Lake Victoria Kyoga Uganda provide first evidence dynamic interaction GLRA. Stable isotope ratios (2H:1H, 18O:16O) support piezometric that primarily discharges to lakes but show further mixing has occurred at one site (Jinja). Layered-aquifer heterogeneity, wherein fluvial-lacustrine sands overlie saprolite, gives rise both rapid slow fluxes which evident recession borehole hydrographs following recharge events. Darcy throughflow calculations suggest direct contributions comprise <1% total inflows lake. Groundwater/surface-water are strongly influenced by changing drainage base (lake) controlled, part, regional climate variability dam releases