Chikabvumbwa Sylvester Richard, Sibale Davis, Marne Ramadan, Chisale Sylvester William, Chisanu Lackson
University of Malawi, The Polytechnic, Civil Engineering Department (Water), Blantyre, Malawi.
Lilongwe University of Agriculture and Natural Resources, NRC Campus, Department of Irrigation, Lilongwe, Malawi.
Heliyon. 2021 Nov 9;7(11):e08346. doi: 10.1016/j.heliyon.2021.e08346. eCollection 2021 Nov.
The geophysical investigation of dambo groundwater reserves using electrical resistivity methods was conducted in Linthipe 4B sub basin in Central region of Malawi. With the increasing over-utilization of shallow wells in dambos for smallholder irrigation, this study was carried out to investigate whether dambo groundwater reserves could serve as sustainable irrigation water sources and to examine the aquifer characteristics in Linthipe sub basin. Vertical Electrical Sounding (VES) points were established in the basin using the Schlumberger configuration array. Data was analysed using IPI2win and Surfer software applications. Contrary to other commercial software applications which are costly for government departments when analysing geophysical data, partial curve matching and one dimensional (1-D) computer iteration techniques were used to interpret the VES curves and the pseudo-cross section resistivity profiles due to their simplicity and cost-effectiveness. The study has revealed that the aquifer properties in the basin are exceptionally variable in terms of state of weathering, depth, thickness, lithology, aquifer recharge configuration, geologic material and hydraulic gradients. These variations showed that the shallow wells in the basin have significant fractures suggesting high water potential for climate smart irrigation usage in the study area. The potential groundwater zones for climate smart irrigated farming were detected at VES 1, 2, 3, 4, 5 and 6 noted by low aquifer resistivity with high values of aquifer thickness. However, VES points, 7, 8 and 9 were likely to be zones of low water bearing potential because they had high values of aquifer resistivity with low aquifer thickness. The findings also validated the effectiveness, timeliness, and efficiency of using vertical electrical resistivity technique in exploring groundwater for irrigation. The results from this study have highlighted that feasible shallow well depth for a sustainable irrigation system is a function of geologic resistance and aquifer thickness when the geologic material has low resistance and broader thickness. This study noted that knowledge of aquifer recharge rates in dambos is required in order to effectively control abstraction rates for sustainable irrigation in basins. There is a need to promote the usage of geophysical studies, reforestation, river basin management trainings and aquifer recharge technologies in exploring sites for shallow well development for irrigation. The study further recommends the usage of geographical information systems (GIS) and Artificial Intelligence (AI) in improving the results of groundwater monitoring studies in Malawi.
在马拉维中部地区的林蒂佩4B次流域，采用电阻率法对水泽地地下水储量进行了地球物理调查。随着水泽地浅井被过度用于小农灌溉，开展本研究以调查水泽地地下水储量能否作为可持续灌溉水源，并研究林蒂佩次流域的含水层特征。利用施伦贝格配置阵列在该流域建立了垂直电测深（VES）点。使用IPI2win和Surfer软件应用程序对数据进行分析。与其他商业软件应用程序相比，政府部门在分析地球物理数据时使用这些软件成本较高，而部分曲线匹配和一维（1-D）计算机迭代技术因简单且具有成本效益，被用于解释VES曲线和伪剖面电阻率剖面图。研究表明，该流域的含水层特性在风化状态、深度、厚度、岩性、含水层补给配置、地质材料和水力梯度方面异常多变。这些变化表明，该流域的浅井有明显裂缝，这表明研究区域具有用于气候智能灌溉的高水潜力。在VES 1、2、3、4、5和6处检测到了气候智能灌溉农业的潜在地下水区，其含水层电阻率较低，含水层厚度值较高。然而，VES点7、8和9可能是低含水层潜力区，因为它们的含水层电阻率较高，含水层厚度较低。研究结果还验证了使用垂直电阻率技术勘探灌溉用水地下水的有效性、及时性和效率。本研究结果强调，当地质材料电阻低且厚度较大时，可持续灌溉系统可行的浅井深度是地质电阻和含水层厚度的函数。本研究指出，为了有效控制流域可持续灌溉的抽取率，需要了解水泽地的含水层补给率。有必要推广地球物理研究、重新造林、流域管理培训和含水层补给技术在勘探灌溉浅井开发地点方面的应用。该研究进一步建议在改善马拉维地下水监测研究结果方面使用地理信息系统（GIS）和人工智能（AI）。
