Abstract

Arumeru district (northern Tanzania) has limited low-fluoride surface water sources for domestic use. Information on the alternative source, groundwater, is also limited in terms of occurrence and quality. Thus, resistivity data in conjunction with hydro-chemical data (fluoride, F⁻; total dissolved solids, TDS; and electrical conductivity, EC) and lithological logs were used to delineate groundwater zones with contrasting quality in the fluorotic zone. The results reveal a thin upper aquifer (~25 m thick) and a lower major aquifer (>100 m thick). Resistivity of between 35 and 60 Ωm represents fresh groundwater hosted in weathered and fractured mafic volcanics, tuffs and breccias. Resistivity of 25–35 Ωm represents intermediate groundwater quality, whereas 15–25 Ωm represents low groundwater quality (TDS >1000 mg/L, F⁻ >10 mg/L) hosted in lahars. The results have been integrated to develop a groundwater potential index map, to guide local communities, water authorities and government in the planning and development of groundwater resources in the region.

摘要

Arumeru区（坦桑尼亚北部）的家用低氟化物地表水有限。关于替代来源地下水的信息在发生和质量方面也很有限。因此，电阻率数据在与水化学数据（氟化物，F结合^-; 总溶解固体，TDS；（电导率，EC）和岩性测井曲线描绘了含氟区域中质量对比鲜明的地下水区域。结果显示出一个薄的上含水层（〜25 m厚）和一个下主含水层（> 100 m厚）。电阻率在35至60Ωm之间，代表着风化和破裂的铁镁质火山岩，凝灰岩和角砾岩中的新鲜地下水。25–35Ωm的电阻率表示中等水质，而15–25Ωm的电阻率表示拉哈尔存在的地下水质量低（TDS> 1000 mg / L，F ⁻ > 10 mg / L）。已将结果综合起来，以开发地下水潜力指数图，以指导当地社区，水务主管部门和政府制定该地区的地下水资源。