ABSTRACT

We investigated water levels in semi-closed grabens of northern Ethiopia. Springs (n = 79), streamflows (n = 48), wetlands (n = 3), endorheic lakes (n = 3), hand-dug wells (n = 48) and boreholes in unconfined aquifers (n = 25) were monitored (2015–2017). Spring discharge fluctuates between wet (2.75 ± 1.5 L/s) and dry seasons (0.87 ± 0.21 L/s) (n = 68, p < .0001). Spring discharge and streamflow were larger at the foot of the escarpment than at the horst (p < .001). The water level of wells varied between horsts and escarpments in the grabens (p < .02). A water level depletion of up to 2.23 m/year occurred in response to withdrawals in the irrigated plains. Importantly, water level fluctuation was faster in streams, springs and hand-dug wells than in boreholes. Striking water level variations in the grabens were linked to rainfall deficit and management scarcity. An integration of surface water and groundwater management responses will bring the water table nearer to the surface; this could mitigate water storage in the fertile and productive grabens.

摘要

我们调查了埃塞俄比亚北部半封闭地堑的水位。监测了泉水 (n = 79)、溪流 (n = 48)、湿地 (n = 3)、内流湖泊 (n = 3)、手挖井 (n = 48) 和无承压含水层钻孔 (n = 25) （2015-2017）。春季流量在湿季 (2.75 ± 1.5 L/s) 和旱季 (0.87 ± 0.21 L/s) 之间波动 (n = 68, p < .0001)。悬崖脚下的泉水流量和径流量大于地垒（p < .001）。地堑中的地垒和悬崖之间的井水位不同（p< .02)。由于灌溉平原的取水，水位下降高达 2.23 m/年。重要的是，溪流、泉水和手挖井中的水位波动比钻孔中的要快。地堑中水位的显着变化与降雨不足和管理稀缺有关。地表水和地下水管理响应的整合将使地下水位更接近地表；这可以减少肥沃和多产的地堑中的蓄水量。