Anthropogenic Impacts on Groundwater Resources in the urban Environment of Dire Dawa, Ethiopia

Abstract This study describes the contribution of anthropogenic factors for groundwater pollution in the urban environment of developing countries. Dire Dawa is one of the oldest urbanized and densely populated city in Ethiopia. The rapid urbanization and unplanned urban growth of Dire is manifested by the mismanagement of municipal wastes that clearly observed in every corner of the city. The groundwater quality shows more of nitrate and chloride caused by the direct influence of human activities. These untreated wastes (liquid & solid) contribute for groundwater pollution particularly in the phreatic aquifer. The municipal wastes and output of industrial activities have highly affected the urban environment since there is no proper treatment and enough urban facilities. From the nature of contaminants and the complexity of hydrogeological settings, this study tried to incorporate and conceptualize the box model with contaminant transport in the phreatic aquifer to reflect the actual situations of Dire Dawa. From groundwater evolution of the basin we have clearly observed that the anthropogenic factors degraded the water quality by tracing the nitrate-chloride spatial trends. One of the most important sources for groundwater pollution is the release of septic effluent in phreatic aquifer which has a direct influence in the shallow wells. The concentration of nitrate becomes degraded in the downstream basin through hydrogeochemical processes by different mechanisms; ion exchange and biochemical denitrification process but still difficult to determine the degradation rate.