Investigation of groundwater resources - A case study in north-west Tanzania using remote sensing analysis and groundwater simulation

Abstract: Globally 884 million people depend on unsafe drinking water, of which 159 million depend on untreated surface water (WHO, 2017). In Tanzania 44% of the popula- tion lack access to safe drinking water (WaterAid, 2017). Women and children in the small city of Chonyonyo, in Karagwe district are walking several hours a day for contaminated drinking water. According to a study, carried out in Tanzania, a shorter walk by fifteen minutes would increase a girls attendance to school by twelve percent (Unicef, 2013). The non-governmental organizations Engineers without borders Sweden and M avuno Tanzania started a project to facilitate a water-supply system from a pumping well to the city of Chonyonyo. If successful the project would change the every-day life of women and children in the city, who would no longer have to collect and carry water the demanding path to the waterhole. The quality of the drinking water would increase and possible outbreaks of illness could be avoided. This thesis makes an attempt to estimate the potential of a groundwater resource by Chonyonyo city, and investigate two suggested borehole locations presented by Mavuno. The drainage basin for the two locations are studied and a hydrological budget for the larger basin has been calculated. The annual infiltration is used as input recharge for a groundwater simulation model in MODFLOW. The bulk part of remaining input parameters are estimated from local drilling and geomagnetic survey reports. The result from the hydrologic budget shows that 50% of annual infiltration would be exploited to meet the fresh-water demand. The sustainability of such exploitation is questionable. The MODFLOW model shows that for maximum withdrawal the limiting factor is the aquifers transmissivity and therefor several pumping wells need to be constructed with appropriate distance from one another. To know the withdrawal capacity of the aquifer test-pumping is recommended.