Gebeyehu Assaminew, Ayenew Tenalem, Asrat Asfawossen
School of Earth Sciences, Addis Ababa University, PO Box 1176, Addis Ababa, Ethiopia.
Department of Mining and Geological Engineering, Botswana International University of Science and Technology, Private Bag 16, Palapye, Botswana.
Environ Monit Assess. 2023 Mar 10;195(4):458. doi: 10.1007/s10661-023-11088-x.
In the semiarid Bulal transboundary catchment of southern Ethiopia, groundwater is the only reliable drought-resilient water source. The central and southern parts of the catchment are dominantly overlain by the transboundary aquifers of the Bulal basalts, while the basement rocks outcrop in the eastern part. This study uses an integrated geographic information system (GIS), remote sensing (RS), and analytical hierarchal process (AHP) to identify and delineate the groundwater potential zones of the semiarid Bulal catchment within the Ethiopian territory. Based on their relative importance to groundwater occurrence and movement, ten input parameters were chosen. According to Saaty's AHP approach, the input themes and each of their distinct features were given normalized weights. A composite groundwater potential zone index (GWPZI) map was generated by integrating all the input layers employing the GIS-overlay analysis technique. The map was validated using the yield of wells from the catchment. The GWPZI map depicts four groundwater potential zones: high (representing 27% of the total area), moderate (20%), low (28%), and very low (25%). The geological feature has the greatest influence on the distribution of groundwater potential. Areas with high potential are mainly overlain by the Bulal basaltic flow, while low groundwater potential zones are in the regolith over the basement rocks. Unlike conventional methods, our novel approach is effective in identifying relatively shallow GWPZs throughout the catchment, and it can be applied in similar semiarid regions. The GWPZI map serves as a quick guide for effectively planning, managing, and developing the catchment's groundwater resources.
在埃塞俄比亚南部半干旱的布拉尔跨界集水区，地下水是唯一可靠的抗旱水源。该集水区的中部和南部主要被布拉尔玄武岩的跨界含水层覆盖，而基岩则出露在东部地区。本研究使用综合地理信息系统（GIS）、遥感（RS）和层次分析法（AHP）来识别和划定埃塞俄比亚境内半干旱布拉尔集水区的地下水潜力区。根据它们对地下水赋存和运移的相对重要性，选择了10个输入参数。根据萨蒂的层次分析法，对输入主题及其各自不同的特征赋予了归一化权重。利用GIS叠加分析技术，通过整合所有输入图层生成了一幅综合地下水潜力区指数（GWPZI）图。该图通过集水区内水井的出水量进行了验证。GWPZI图描绘了四个地下水潜力区：高潜力区（占总面积的27%）、中等潜力区（20%）、低潜力区（28%）和极低潜力区（25%）。地质特征对地下水潜力分布的影响最大。高潜力区主要被布拉尔玄武岩流覆盖，而低地下水潜力区则位于基岩之上的风化层中。与传统方法不同，我们的新方法在识别整个集水区相对较浅的GWPZ方面是有效的，并且可以应用于类似的半干旱地区。GWPZI图可作为有效规划、管理和开发集水区地下水资源的快速指南。
