Properties of shallow thin regolith aquifers in sub-Saharan Africa: a case study from northwest Ethiopia
Properties of shallow thin regolith aquifers in sub-Saharan Africa: a case study from northwest Ethiopia
复制标题
撒哈拉以南非洲浅薄风化层含水层的特性：埃塞俄比亚西北部的案例研究
DOI：
10.13140/rg.2.2.23154.50880
复制
发表时间：
2016
期刊：
影响因子：
--
通讯作者：
D. Walker
中科院分区：
文献类型：
--
作者：
D. Walker
在埃塞俄比亚西北部的两个地区成功地对浅手挖威尔斯井进行了抽水试验。分别分析了压降和回收率数据，结果一致，证实了方法的适用性。水力传导率估计值范围为0.2至6.4米/天（平均值= 2.3米/天，中位数= 1.6米/天），在旱季和范围为2.8至22.3米/天（平均值= 9.7米/天，中位数= 6.5米/天），在雨季时，地下水位较高。这一差异表明了挖掘尽可能深的威尔斯井的重要性，以增加拦截更多渗透（含水）层的可能性。具体收益率估计的范围较宽（0.00001至0.32），虽然平均值为0.09（中位数为0.08）是合理的，但不确定性更大。据估计，井产量平均为0.5升/秒，但在雨季会增加到>1升/秒;因此，小规模灌溉是可以实现的，这可能会减少对雨水灌溉农业的依赖。这些来自风化玄武岩风化层的结果增加了关于撒哈拉以南非洲浅层地下水资源的稀少的现有数据。附近和远处威尔斯井的结果一致性表明，浅层含水层物质的同质性使调查结果可高度转移到埃塞俄比亚其他地区。对含水层特性的这种了解有助于建立模型，以估计气候多变性和变化的影响，并制定浅层地下水资源的可持续管理战略。
Pumping tests have been successfully conducted on shallow hand-dug wells in two areas of northwest Ethiopia. The drawdown and recovery data were analysed separately providing consistent results confirming suitability of methods. Hydraulic conductivity estimates ranged from 0.2 to 6.4 m/d (mean = 2.3 m/d, median = 1.6 m/d) in the dry season and ranged from 2.8 to 22.3 m/d (mean = 9.7 m/d, median = 6.5 m/d) in the wet season when the water-table was higher. This difference indicates the importance of excavating wells as deeply as possible to increase the likelihood of intercepting more transmissive (water-bearing) layers. Specific yield estimations have a wider range (0.00001 to 0.32) and are more uncertain though the mean of 0.09 (median of 0.08) is reasonable. Estimates of well yield average 0.5 l/s though this increases to >1 l/s in the wet season; giving opmitism that small-scale irrigation is achievable, therefore, potentially reducing the reliance on rain fed agriculture. These results from weathered basalt regolith add to the sparse available data on shallow groundwater resources in subSaharan Africa. Consistency of results from nearby and distant wells indicates homogeneity of shallow aquifer materials giving a high transferability of findings to other areas of Ethiopia. This knowledge of aquifer properties facilitates modelling for estimating impacts of climate variability and change, and for developing sustainable management strategies for shallow groundwater resources.