Structures such as seawalls and groynes should be built as a coastal protection measure only when other options are not feasible, a study on coastal erosion and coastal management in Thiruvananthapuram district conducted by the Kerala Sastra Sahithya Parishad (KSSP) has suggested.
The experience in Thiruvananthapuram district is that, in some instances, such structures have aggravated coastal erosion and caused it to spread to nearby beaches, says the study prepared by V. Harilal, chairperson, Environment Subject Committee, KSSP, and Dr. K.V. Thomas, former group head, National Centre for Earth Science Studies (NCESS).
Moreover, many of these structures have not lasted their expected span of 25-30 years. This alone is indicative of their limitations, the study notes. Another shortcoming is that in some locations, the natural protection offered by beaches was lost once these structures were built and they themselves were weakened through processes like scouring.
The study notes that future coastal protection measures should take into account that such solid structures may have to be redesigned due to climate change and rise in sea levels.
Eighteen groynes were built at Chilakkoor, south of Varkala, 125 years ago. Construction of more seawalls and groynes began by the 1950s. While many of the old structures still remain intact, subsequent ones—such as the ones in Kollengode, Paruthiyoor, Panathura, Poonthura-Shangumugham and Thazhampally-Poothura—have either been destroyed or rebuilt. Few attempts have been made for an authentic assessment of their structural efficiency, the report notes. Moreover, the frontal beach, beyond the seawalls, gradually vanished.
Among other things, the report has also called for a comprehensive revisit of the environmental impact assessment (EIA) performed for the Vizhinjam seaport project using the latest data available to accurately determine the impact of this mega project on the coast. It also noted that the earlier EIA had given rise to complaints that it was riddled with flaws.