CHALLENGES IN URBAN GROUNDWATER (Invited Presentation)

With over half the world’s population now living in urban areas, the protection and management of urban groundwater has become a major global challenge. Historically, groundwater has played a pivotal role in much of the world's urban development. Problems begin to emerge when shallow groundwater becomes contaminated by urban-sourced chemicals and deeper reserves fail to meet the growing demand. In many cities, a common response is to import water from peri-urban well fields and remote surface water sources. This “solution” often exacerbates the groundwater management problem with leakage of imported surface water elevating groundwater levels, threatening tunnels, engineering structures, and electrical utilities with flooding and/or instability, and accelerating the release of degraded groundwater to urban springs, wetlands and rivers. Urban groundwater is no longer simply a developing-world “megacity” problem. Polluted urban springs and rising groundwater levels in cities throughout Europe and parts of North America demonstrate a modern reality - urban groundwater cannot be ignored - it requires an appropriate level of protection and must be proactively managed whether or not it is used for potable supply. Fortunately, we have made important advances in the science of urban groundwater during the past twenty years including our understanding of the urban water balance and the role of “urban karst”, contaminant source characterisation, recharge management and methods of assessing aquifer vulnerability. We have also seen development of some excellent ground and surface water modelling tools, some of which are linked with GIS and urban databanks to provide the ultimate aid for resource management decision-making. Sadly, we rarely use them! Finally, our greatest challenge is to ensure that the vital role groundwater plays in the urban water cycle is properly acknowledged by urban planners and policy makers. It is too often overlooked. Integrated Water Resources Management (IWRM) and its multi-faceted, integrative approach to water systems management has been widely touted as the solution to the world’s water issues but, in truth, it has not served us well in the urban areas of the world. Failure to recognise the unique and special attributes of groundwater represents one of the lost opportunities of IWRM.