Hydrological Modeling of Artificial Recharge of Groundwater for Sustainable Water Supply in Dodoma City

Abstract

Groundwater is an important resource that supports the life of people and the surrounding ecosystem in the world. It is the prima y source of safe water to semi-arid areas characterized by limited surface water. In Af rica, water scarcity has been hitting major cities and towns. In Tanzania, Dodoma has lon g experienced shortages of water. Owing to the recent transfer of all significant off ices from Dar es Salaam to Dodoma, the City's population has drastically increased. The pr ima y source of water in the City is the Makutupora aquifer. The growing human population ha s resulted in high demand for water use, which has led to the overexploitation of gr undwater aquifer. Therefore, this study was carried out using a Modular finite-differ ence flow model (MODFLOW) to model artificial recharge products to replenish gro undwater in the Makutupora aquifer to ensure water supply sustainability in the City. Bef or simulation of the artificial recharge was done, groundwater storage was estimated using a vailable borehole data and GIS technique. The results indicated that the total gro undwater storage in the Makutupora aquifer was about 24.8 BCM (Billion Cubic Meters). The MODFLOW packages used include well package (WEL), General Head Boundary P ackage (GHB), Evapotranspiration package (EVT), Drain package (DR N), and Recharge Package (RCH). A total of 21 piezometers were used for mode l calibration. The statistical calibration was also done to validate the model's c alibrated parameters. After simulation of the steady-state reference period, the other fou stress periods were simulated, considering the projected population and water dema nd. The planned injection wells to the model in the first, second, third, and fourth t ansient state periods resulted in a safe yield of 168,857 m/day, 197,760 m/day, 360,000 m/day, and 600,430 m /day, respectively. The recommended artificial recharge s ource is water from the Kinyasungwe River that flows during rainfall time, generally fr om November to May. One of the W. P. Venance, G. V. Lugomela and V. G. Masanja 2 recorded years (2007) indicated a flow of up to 23. 646 Million Cubic Meters (MCM). The recommended artificial recharge is possible due to the aquifer's storage capacity of 247.84 Million Cubic Meters (MCM). Other flows in s mall streams within the well field were recommended in creating artificial recharge st ructures to add more water to the aquifer and natural recharge. Therefore, informatio n fr m this study could be used by engineers when constructing artificial engineering structures to replenish the water pumped from the Makutupora aquifer.