Customizing a water balance model to the hydro-climate conditions of the Choke Mountain watershed in Ethiopia for water potential assessment and economic valuation

Abstract

Numerous research efforts have explored novel strategies to alleviate water scarcity in various regions of Ethiopia. In this context, growing attention has been directed toward assessing the economic value of multiple watersheds to inform sustainable water resource management. This study develops and customizes a water balance (WB) model tailored to the hydro-climatic characteristics of the Choke Mountain watershed (CMW) to evaluate its water potential and support economic valuation. By integrating multiple data sources, the customized model provides improved alignment with natural hydrological dynamics compared to conventional WB models. Over the past four decades, groundwater levels in mountainous areas have declined at a faster rate than in lowland regions. The model incorporates altitude-sensitive precipitation estimates, highlighting the critical role of highland areas as water sources. The total annual water from terrestrial sources within the CMW is estimated at 13.86 billion m3, contributing significantly to downstream flows across borders. The annual economic value of CMW water resources is estimated at $133.4 billion. Model results also indicate that a 10 m decline in peak elevation of the CMW leads to a 0.04 mm d−1 reduction in precipitation, highlighting the region’s vulnerability to topographic and climatic changes. Furthermore, the Grand Ethiopian Renaissance Dam (GERD) is estimated to lose over 1.386 billion m3 of water annually due to this decline, corresponding to an economic loss of $0.5 billion per year. These findings emphasize the need for comprehensive, national-scale economic valuation frameworks to support effective and sustainable water resource management strategies.