The assessment of potential impacts of open cast gold mining on the regional groundwater flow system in hard rock environments: with special reference to Ghana

[摘要] We consider a simple semi-empirical scoping calculation in conjunction with mathematical models to estimate the radius of impact (Ri) and to determine the circumstances under which gold mines in Ghana are likely to have adverse effect on water levels and volumes in surrounding villages/farms. The approach involves the assessment of local mine geometries, collation and examination of hydraulic conductivity data and the assessment of recharge infiltration rate.Most of the models used with the entire conductivity dataset (Group A) predicted very close radius of impacts to mine with less than few 100m with a median distance of 400m from the mine’s edge. Although it is expected that 25% of cases could reach up to 2km and further if the system was anisotropic. Derogation of water level and volume is more of a problem for Group B and C aquifer systems of higher conductivity values. Model results show that 50% of cases could reach up to 3.6km with a range of 2.7km to 5.1km, and 3km with a range of 2km to 4.6km from mine centre respectively. Nevertheless, Ri could reach 7.6km and further in extreme cases if the system was anisotropic. With regards to Ghana, by constraining conductivity values using water volumes produced by mines in Ghana, and comparing with the model output, it is tentatively suggested that the most likely Ri values are those calculated with the Group B dataset. It should, however, be noted that this results are very sensitive to hydraulic conductivity, and therefore there is the need in Ghana to publish conductivity and volume data to enable suggestions from this work to be confirmed.

[发布机构] University:University of Birmingham;Department:School of Geography, Earth and Environmental Sciences

[关键词] G Geography. Anthropology. Recreation;GE Environmental Sciences