Abstract
Climate change and increase of population is expected to affect coastal groundwater systems in many parts of the world. Changes in the rainfall pattern due to climate change may also lead to uncertainties in the supply and management of the groundwater resources. The objective of this study is to evaluate the impact of climate change on seawater intruded coastal aquifer located north of Chennai, India by density dependent groundwater modelling and to identify suitable measures of mitigation. This aquifer system is affected by seawater intrusion since the year 1969 due to over extraction of groundwater for agriculture and drinking water supply to Chennai city. Since the climate change projections for this area is available until the year 2030, the density-dependent model was used to predict the changes in hydrological stresses on the groundwater head until this year. The impact of sea level rise on seawater intrusion was noticed up to about 5 km from the coastline. The 10% increase in rainfall recharge with an additional check dams and 1 m increase in crest level of all the existing check dams is expected to increase the groundwater head by about 3 m in the upper and 5.5 m in the lower aquifers. This will also decrease the chloride concentration by about 1000 mg/l in the upper and 700 mg/l in the lower aquifers respectively. Thus, the construction of Managed Aquifer Recharge structures along with the 10% increase of rainfall pattern due to climate change will decrease the chloride concentration and restore in this seawater intruded aquifer in future.
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