Impact of climate variability on groundwater in coastal cities

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Population growth, sprawling cities and the effects of climate change seriously threaten the sustainability of global water supplies. Pro-active resource management decisions are required, but such efforts will prove meaningless unless reliable predictions can be made of the impact that rapidly changing conditions will impart upon the water cycle and water resources. The threat is especially severe in coastal cities which host close to 50% of the global population. In many coastal cities, the management and protection of groundwater is already challenged by accelerating demand for the resource in the face of depleted natural recharge, pollution from urban-sourced contaminants and (for sea coasts) the intrusion of seawater. Climate variability and changing sea levels will intensify such resource management problems by altering the recharge regime and stimulating the movement of both contaminants and the fresh-saline water interface. Applying urban water system models that have been calibrated with field data to simulate the complex recharge conditions and "karstic" groundwater flow behaviour that typify urban aquifer systems, we will address fundamental research questions regarding the transient response of coastal aquifers to conditions imposed by climate variability: e.g. 1) How will climate change affect the nature and seasonality of urban recharge? 2) How will groundwater levels beneath coastal cities respond to changing sea/lake levels, and to what extent will rising sea levels promote the intrusion of seawater? 3) Will a decline in sea/lake level accelerate the release of contaminants stored in urban aquifers to receiving water bodies? 4) Over what time frame will system changes occur? 5) What are the options for ameliorative action and when should they be implemented? The research is novel in that very little is known about the potential impacts of climate change on urban aquifers, particularly those in coastal areas where sea levels are expected to rise and, in some cases, fall at rates that are unprecedented in modern times. Over 5 years, the work will involve a minimum of 12 HQP (2 PhD students, 5 MSc students and 5 final year undergraduates).