Comparative evaluation of groundwater recharge in response to soil and water conservation measures using QSWAT+ model in North-eastern Ethiopian highlands

Abstract

The main environmental issue in the Ethiopian highlands is land degradation, resulting from intensive cultivation, poor land-use management, and extreme climate.  Agriculture in Ethiopia, especially in the northeastern highlands, is the primary sector to be affected by land degradation and climate extremes. To combat and augment such problems, irrigation from surface and groundwater sources is being used for agricultural production in the highlands of Ethiopia. However, water abstraction exceeded the rate of natural recharge, necessitating artificial mechanisms to replenish groundwater at a rate higher than natural recharge. Despite significant investments in soil and water conservation to enhance artificial recharges in the Northeastern highlands of Ethiopia, the impact of watershed treatment on groundwater recharges and hydrological responses is seldom assessed. For a reliable assessment of the impact of soil and water conservation measures at the watershed level, hydrological modelling is crucial. Thus, this study employed the QSWAT+ model to evaluate and compare groundwater recharge between treated and untreated micro-watersheds in the northeastern highlands of Ethiopia in response to soil and water conservation. The result shows that 47% of the watershed treatment could improve 198% of the annual groundwater recharge, achieving an overall Nash-Sutcliffe Efficiency (NSE) values of 0.91 and 0.85 with Coefficient of Determination (R²) values of 0.94 and 0.87 in the untreated and treated micro-watershed, respectively. The current efforts of soil and water conservation initiatives should be continued in a systematic and coordinated manner to reverse land degradation, create resilience to climate shocks, and ensure sustainable natural resource management.