Groundwater in urban development : a review of linkages and concerns

Urban population growth in Asia and Latin America is occurring on a scale, and at a rate, unprecedented in human history. Many of the cities are sited on unconfined or semi-confined aquifers, depend on groundwater for much of their water-supply, and apply or dispose of most of their liquid effluents and solid residues to the ground. Urbanization causes radical changes in groundwater recharge, modifying existing mechanisms and introducing new ones. Concomitantly groundwater quality degradation is reported from a wide range of geographical locations, both within the urban area itself and in downstream alluvial aquifers. Its severity varies considerably with hydrogeological environment, development level and coverage of waterborne sewerage, but it is often the cause of increasing freshwater scarcity, escalating water-supply costs and a growing human-health hazard. As such it is an issue that urgently needs to be addressed.