Shifting sands

Tamil Nadu's coastline faces erosion due to climate change, prompting the need for innovative solutions for coastal protection.

Tamil Nadu, with the second longest coastline in India at 1,076 kilometres, has long thrived on its rich maritime heritage. Its coast has been the cornerstone of the State’s prosperity for ages. Yet, as climate change drives up the sea level, the boundary is shifting between the land and the sea.

Erosion eats away at the coast, threatening the livelihood of fishers and others who have made their homes there. Development projects, intended to bolster economic growth, and ‘solutions’ to prevent sea erosion are only worsening the situation by altering the shoreline and compounding the challenges faced by local communities.

To deal with sea erosion, it is crucial to understand how the coast erodes in Tamil Nadu and examine the specific vulnerabilities of the State’s coastline. Sea erosion happens when the shoreline wears away by the movement of sand and water. In Tamil Nadu, for most of the year (about eight months), the wind and the sea current flow from the south to the north, carrying sand along with them. During the northeast monsoon (for about four months), they reverse their direction.

When hard structures like ports, breakwaters, or groynes are built extending to the sea, they block the natural movement of sand. As a result, sand piles on one side of these structures, and the opposite side loses sand and begins to erode. This imbalance accelerates coastal erosion on the side where sand is no longer deposited, causing waves to advance further inland and increasing the risk to the coastal areas.

A study conducted by Anna University’s Centre for Climate Change and Disaster Management reveals that 76% of the coastline in Chennai, Tiruvallur, and Chengalpattu, running to 102.2 km, is at risk from cyclones, coastal erosion, and the sea level rise. Tiruvarur, Nagapattinam, and Chengalpattu are especially vulnerable, owing to high salinity and low elevation. Over 60% of the coastline in Kanniyakumari, Chennai, and Cuddalore is also exposed to climate change, influenced by land use and infrastructure.

The National Centre for Coastal Research (NCCR) reports that 422.9 km (42.7%) of Tamil Nadu’s mapped coastline of 991.4 km is facing erosion, exacerbated by hard structures such as groynes, jetties, and piers, with the number of these structures increasing since 2022. Tiruvallur and Kanniyakumari have the largest proportion of their coastal areas occupied by ports, harbours, and coastal protection structures, according to the NCCR. Over the past five years, the fisherfolk of Karikattukuppam, a coastal hamlet near Muttukadu in Chengalpattu district, have observed the sea inching closer to their homes. During cyclonic storms and on full and new moon days, they have had to watch over their boats and fishing gear. This situation is common in several villages across Chengalpattu.

In response to the fishing community’s concerns, the Fisheries Department in 2023 applied its standard solution: groynes. Unfortunately, this approach has led to significant challenges for villages north of Karikattukuppam, like Reddy Kuppam in Kanathur. Fisherfolk of Reddy Kuppam have had to move their boats to Karikattukuppam, where two groynes offer temporary shoreline protection.