Modelling Base flow Enhancement in Response to Soil and Water Conservation Measures using QSWAT+ in the Northeastern Highlands of Ethiopia

Abstract

Land degradation has a significant impact on the Northeastern highlands of Ethiopia, resulting from topographic complexity, intensive cultivation, poor land-use management, and erratic rainfall. As the water deficit is one of the limiting factors for rainfed agriculture, it worsens the scenario in drought-prone areas. Irrigation from stream base flow is considered as a solution to reduce moisture shortage in the Northeastern highlands to support agriculture and sustain rural livelihoods. However, recurrent drought, land degradation, and low dry period base flow have a significant negative impact on the availability of water for irrigated agriculture. To solve such problems, massive watershed scale soil and water conservation projects has been implemented on the highlands of Ethiopia since 2010. Despite significant investment in conserving soil and water resources at watershed scale, most watershed treatments lack impact evaluation and estimation of enhanced base flow. To fill this gap, the QSWAT+ model was used to analyze hydrological phenomena and assess how watershed changes impact the hydrological cycle using 17 years of meteorological input data with the specific objective to compare base flow enhancement on paired micro-watersheds, Amanuel and Degnu, in response to watershed treatment. The results indicate that watershed treatment could enhance 79% of the base flow due to 47% of the watershed treatment. QSWAT+ successfully models baseflow, achieving Nash-Sutcliffe Efficiency (NSE) values of 0.92in both, and Coefficient of Determination (R²) values of 0.93 and 0.92 for Amanuel and Degnu, respectively. The model results help effectively allocate water resources and implement sustainable watershed management practices.

Keywords : Baseflow, Micro-watershed, QSWAT+, Soil and Water Conservation

DOI: 10.7176/JEES/15-5-03

Publication date: October 31st 2025