About 63 per cent of the coastline of Kerala is eroding, shows the shoreline change assessment of Kerala cost released by Union Minister of State for Environment and Forests Jairam Ramesh here on Monday. The coastline includes artificial coast built using seawalls, riprap revetments or groynes.

About 53 per cent of the State’s coast now have artificial coast while 10.3 per cent are eroding coastline; experiencing high, medium and low levels of erosion.

The assessment says that the artificial coasts are essentially eroding coasts and is managed by structures. It is therefore only appropriate to consider them as eroding coasts.

This indicates that only 37 per cent of Kerala's coast is "natural" (no intervention). Of this, accretion is dominant along 24 per cent of the coast, particularly in the Ernakulam District, which has an intricate network of backwaters (Vembanad Lake). Only about eight per cent of the 590 km coastline of Kerala is stable, without erosion or accretion.

There are nine coastal districts in Kerala which have key infrastructure facilities such as ports and harbours and the intricate network of backwaters and wetlands along the coast. District wise statistics indicate that erosion is dominant in all the coastal districts of Kerala, with minimum erosion in Thrissur District (1.5%) and the maximum in Thiruvananthapuram (23%).

Artificial coasts are dominant at Kollam and Ernakulam (80%). Maximum accretion occurs at Thrissur (41 %) and the minimum at Kollam (5.5%).

It is possible therefore to correlate high accretion to less artificially managed coasts and vice versa. Stable coasts are more prevalent along the coast of Thiruvananthapuram (17%).

The assessment represents shoreline change over 38 years from 1972 to 2010. The evaluations are based on comparing five historical shorelines extracted from satellite imageries. The recent shorelines were derived from Landsat-5 imageries for 1990, 2000, 2006 and LISS III (Live Internet Seismic Server) images for 2010 supported by limited field surveys.

The mapping of the coastline was undertaken by the Ministry of Environment and Forests in collaboration with the National Centre for Sustainable Coastal Management and Society of Integrated Coastal Management. It notes that attempts to halt the natural process with seawalls and other hard structures only shifts the problem subjecting downdrift coastal areas to similar loss of land. Besides, some of the beaches, dunes, barrier beaches, salt marshes and estuaries are threatened and would disappear as the sand sources that feed and sustain them are eliminated.