Hydrogeology of Volcanic Highlands Affects Prioritization of Land Management Practices

Water

Gashaw G. Addis¹  Seifu A. Tilahun²  Dessalew W. Aynalem²  Anwar A. Adem²  Mulugeta Azeze²  Tammo S. Steenhuis²  Wolde Mekuria³ 

[1] Amhara Design and Supervision Works Enterprise (ADSWE), Bahir Dar 6000, Ethiopia;Faculty of Civil and Water Resources Engineering, Bahir Dar Institute of Technology, Bahir Dar University, Bahir Dar 6000, Ethiopia;International Water Management Institute, Addis Ababa 2689, Ethiopia;

关键词: erosion;    Ethiopian Highlands;    fault;    geology;    hydrology;    land and water management;   

DOI  :  10.3390/w12102702

来源: DOAJ

【 摘 要 】

Volcanic highlands supply water to 40% of the world’s population. Soil degradation threatens this water supply. Studies on geohydrology that affect the effectiveness of land and water management (LWM) practices in reducing soil degradations are limited. To aid in the effectiveness of LWM practices, we conducted a field experiment in the Gomit watershed in the semihumid Ethiopian Highlands on the interaction of hydrogeology and LWM practices. We found that in a watershed with strongly faulted tertiary basalt, 30% of the rainfall was drained through faults to another basin. Consequently, the discharge at the outlet was less than half of that of other watersheds with quaternary basalts. Despite the high sediment concentration, i.e., around 15 g L⁻¹, in the Gomit watershed, the sediment yield of less than 4 Mg ha⁻¹ a⁻¹ was below average for the agricultural watershed in Ethiopia because of the low runoff response. While some faults facilitated drainage, others acted as a barrier. Groundwater stored behind the barriers was used as a municipal potable water source. Since the effectiveness of LWM practices depends on the amount of erosion that can be prevented, considerations of country-wide prioritizing of investments in land and water management practices should include the geology of the watersheds.

【 授权许可】

Unknown