Seawater intrusion and submarine groundwater discharge along the Indian coast.

Intrusion of seawater into the coastal aquifers is a major concern as it affects the quality of groundwater. The objective of this study is to delineate the extent of seawater intrusion in the Indian coast based on previous studies and estimate the area as well as locations of seawater intrusion and submarine groundwater discharge based on the groundwater level of the years 2007 and 2017. Several researchers have reported seawater intrusion in the coastal regions of India by different methods of investigation. These studies indicate that the east coast of India is affected greater than the west coast by seawater intrusion. The maximum extent (about 14 km) of seawater intrusion in India is reported in regions north of Chennai. It is estimated that around 7% of the total coastal area is affected by seawater intrusion, where groundwater is below mean sea level. Around 57% of the coastal area of India has groundwater level in the range from 0 to 10 m msl. Future research needs to focus on the areas where seawater intrusion and submarine groundwater discharge were identified based on this study.