Interactions eau souterraine/eau de surface sur des surfaces profondément altérées de faible relief: cas des lacs Victoria et Kyoga, Uganda Interacciones agua subterránea/agua superficial en superficies profundamente meteorizadas de bajo relieve: evidencias de los Lagos Victoria y Kyoga, Uganda 深度风化的低地势地下地表水相互作用:来自乌干达维多利亚湖和基奧加湖的证据 Interacções água subterrânea/água superficial em zonas aplanadas profundamente meteorizadas: evidência a partir dos Lagos Vitória e Kyoga, Uganda

Owor, Michael; Taylor, Richard; Mukwaya, Christine; Tindimugaya, Callist

Interactions eau souterraine/eau de surface sur des surfaces profondément altérées de faible relief: cas des lacs Victoria et Kyoga, Uganda Interacciones agua subterránea/agua superficial en superficies profundamente meteorizadas de bajo relieve: evidencias de los Lagos Victoria y Kyoga, Uganda 深度风化的低地势地下地表水相互作用:来自乌干达维多利亚湖和基奧加湖的证据 Interacções água subterrânea/água superficial em zonas aplanadas profundamente meteorizadas: evidência a partir dos Lagos Vitória e Kyoga, Uganda | Groundwater/surface-water interactions on deeply weathered surfaces of low relief: evidence from Lakes Victoria and Kyoga, Uganda

2011

Owor, Michael | Taylor, Richard | Mukwaya, Christine | Tindimugaya, Callist

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

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