The Response of Saline Intrusion in Heterogeneous Aquifers to Tidal Change

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The world's population likes living by the sea. Currently 53% of people live on the 10% of the earth's surface that is within 200km of the coast. This is forecast to rise to 75% by 2050. Meeting the needs of coastal communities forms one of the major challenges facing society in the 21st Century.High population density in these areas generates a suite of environmental stresses that require engineering solutions. Foremost amongst these is the provision of sustainable fresh water supplies, often in areas that are already water-stressed. With its widespread availability and resilience to drought, groundwater can play a vital role in meeting this need, although a delicate balance exists between fresh groundwater and seawater in coastal aquifers. Where too much water is extracted, saltwater can enter water supplies in a process called saline intrusion (SI). The extent of this saline intrusion is governed by the levels of use of groundwater resources (i.e. water supply (abstraction wells)), along with geological and climatic conditions. Over pumping, particularly during periods of drought, can result in SI into abstraction wells leading to the loss of supply or the exposure of the population to contamination and the risk of adverse health impacts. The contamination of coastal water resources is pervasive across every inhabited continent and represents an ongoing challenge for water managers where groundwater is often the only water used.This project compliments the EPSRC funded SALINA project, a collaboration between Queens University and Imperial College London and its associated industrial partners. It will directly investigate at laboratory and site scales, using both experiment and simulations, the influence that the tidal cycle and extreme tidal events has on the movement a saline intrusion. The complexity of the dynamic movement of the interface will be further added to by consideration of the effects of abstraction, heterogeneity and fractures on the system response.