Development of a Hydrogeological Conceptual Model for Shallow Aquifers in the Data Scarce Upper Blue Nile Basin
Development of a Hydrogeological Conceptual Model for Shallow Aquifers in the Data Scarce Upper Blue Nile Basin
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DOI：
10.3390/hydrology6020043
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发表时间：
2019-05
期刊：
影响因子：
3.2
通讯作者：
D. Walker;G. Parkin;J. Gowing;A. Haile
中科院分区：
文献类型：
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作者：
D. Walker;G. Parkin;J. Gowing;A. Haile
撒哈拉以南非洲的农村社区通常依赖浅手挖井和泉水；因此，浅层含水层是极其重要的水源。增加浅层地下水的利用可以通过对贫困、饥饿和健康产生积极影响来帮助实现多个可持续发展目标（SDG）。然而，对这些浅层含水层的研究和了解很少，部分原因是撒哈拉以南非洲许多地区缺乏现有的水文地质信息。本研究基于广泛的实地调查和公民科学计划的实施，为埃塞俄比亚西北部的丹吉拉沃尔达（Dangila wereda）（地区）开发了水文地质概念模型。地质和水点调查显示，薄层（3-18 m）风化火山风化层含水层覆盖在渗透性极低的玄武岩上。水化学表明，玄武岩裂隙带和熔渣带内的深层地下水与浅层地下水没有（或联系很差）。同位素分析和井监测表明浅层地下水流动路径不一定与地表水流动路径一致。普遍存在的季节性洪泛区的特征类似于南部非洲文献中详细描述的“dambos”。抽水测试、补给评估和水文气象分析表明风化层含水层显示出提高利用率的潜力。这项研究可转移到覆盖埃塞俄比亚大部分地区的浅层火山风化层含水层，并普遍存在于整个东非大裂谷和非洲大陆其他几个地区。
Rural communities in sub-Saharan Africa commonly rely on shallow hand-dug wells and springs; consequently, shallow aquifers are an extremely important water source. Increased utilisation of shallow groundwater could help towards achieving multiple sustainable development goals (SDGs) by positively impacting poverty, hunger, and health. However, these shallow aquifers are little studied and poorly understood, partly due to a paucity of existing hydrogeological information in many regions of sub-Saharan Africa. This study develops a hydrogeological conceptual model for Dangila woreda (district) in Northwest Ethiopia, based on extensive field investigations and implementation of a citizen science programme. Geological and water point surveys revealed a thin (3–18 m) weathered volcanic regolith aquifer overlying very low permeability basalt. Hydrochemistry suggested that deep groundwater within fractured and scoriaceous zones of the basalt is not (or is poorly) connected to shallow groundwater. Isotope analysis and well monitoring indicated shallow groundwater flow paths that are not necessarily coincident with surface water flow paths. Characteristics of the prevalent seasonal floodplains are akin to “dambos” that are well-described in literature for Southern Africa. Pumping tests, recharge assessments, and hydrometeorological analysis indicated the regolith aquifer shows potential for increased utilisation. This research is transferrable to the shallow volcanic regolith aquifers that overlie a substantial proportion of Ethiopia and are prevalent throughout the East African Rift and in several areas elsewhere on the continent.