Rising sea levels will become a big problem for the city of Chennai in less than a century from now. As per a study published by researchers from Anna University and National Water Centre, UAE University, by the year 2100, a stretch from Adyar near Foreshore Estate to Thiruvanmiyur which lies on the South Chennai coast could be submerged in water. Moreover, water from the sea will enter at least 40 metres into the land from the current shore.
This will have major issues, mainly cause the mixing of seawater with groundwater, due to which the aquifer already under threat due to excessive extraction of water will further be affected. The area which was studied is 35 sqkm Bay of Bengal on the eastern side and Adyar River in the north; Buckingham Canal towards the west along with Muttukadu backwater to the south for identifying the impact of sea level rise and tidal effects on the complex aquifer.
At least 30 spots, for the study, borewells were dug. This area has water bodies all around that remain vulnerable to seawater intrusion, putting the groundwater aquifer at risk.
Three scenarios were studied including one being the high tide and low tide with sea level rise on a six-hour interval; without taking tidal effect into consideration and sea level rise and finally with sea level rise of 2mm annually up to 2100.
The simulation of the groundwater table without taking sea level rise into consideration shows a reduction in the groundwater table by a 0.35m on the Adyar to Thiruvanmiyur stretch, which will result in sea water intrusion. However, the groundwater table remains stagnant towards Thiruvanmiyur to Muttukadu.
On the other hand, if sea level rises by 2 mm each year, the simulation of the groundwater table increases the groundwater table by 0.15m from Adyar to Thiruvanmiyur and by 0.27m from Thiruvanmiyur to Muttukadu.
The simulated tidal impact on groundwater is nothing compared with the impact of sea level rise.
For the past half a century, a 3.6mm rise in sea level a year has been reported in the Bay due to melting of glaciers in the Himalayas. The rise in the Bay of Bengal is way more than any other Asian regions. The study has taken a 2007 report in consideration and mentioned that if sea level rises by a metre, 60 km of coastal inland can be inundated.
Image Credit: Holiday Inn, Story Source: TOI