Hydrogeological Framework and Groundwater Recharge Estimation in the Tongo District of the Upper East Region of Ghana

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JUNE, 2016
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Abstract
Surface water in most parts of the UER faces two challenges. The resource is mostly inadequate due to frequent failure and the uneven distribution of rainfall and sometimes also polluted due to anthropogenic activities. This situation has brought about the use of groundwater as a more reliable alternative for both domestic and agriculture purposes. The current reliance on groundwater has brought about a decline in the resource due to over abstraction from aquifers within the region which may potentially lead to depletion and give way to ecological challenges. There is therefore the need for good management of the aquifer by giving much consideration to its recharge areas and water sources. This study was conducted to assess the hydraulic conductivity and transmissivity characteristics of the soil overlying the aquifer in the Tongo district. This study also estimated the aquifer’s geometry and the physio-chemical parameters of both surface water and groundwater in the area. The hydraulic conductivities estimated ranged between 0.54 m/d and 1.53 m/d indicating that the aquifer is an unconsolidated sedimentary soil. Analysis of grain-size distribution showed the overlying to be predominantly medium sand. The soil’s transmissivities ranged between 1.82 m2/d and 22.2 m2/d. Even though the physico-chemical parameters indicate that the water in the aquifer is of good quality, the low soil transmissivity values suggests that not much water can be abstracted from the aquifer for local water supply. The geometry of the aquifer system within the region was delineated using the inverse distance weighting technique. The technique estimated that, depth to water table ranged between 0.6 and 23.7 m, and depth to bedrock between 4.5 and 40.8 m. The saturated aquifer thickness also ranged between 0.3 and 49.5 m. These parameters suggest that the aquifer is indeed shallow and can be susceptible to pollution. Estimation of the aquifer recharge using the chloride mass balance method established a mean recharge rate of 109.3 mm/yr which suggests that only about 11% of precipitation in the area recharges the aquifer. This study recommends a long-term monitoring plan for early detection of groundwater contamination and aid to define the aquifer’s geometry extensively. It is again recommends for communities to construct more open wells to recive direct recharge as well as ensuring good agricultural and sanitation practices to avoid groundwater pollution.
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A Thesis submitted to the Department of Civil Engineering college of Engineering in partial fulfilment of the requirements for the degree of Master of Science Water Resources Engineering and Management..
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