Seashore spanning 55-hectares in coastal Maha submerged near Devghar

Nagpur: Researchers, using satellite images, have identified the submergence of a 55 hectare (ha) area — nearly ten times the size of Mumbai’s Wankhede Stadium — near Devghar in Raigad district. According to experts, this indicates a worrying sign of coastal inundation and extreme shoreline erosion.

Preliminary data show that between 1990 and 2022, there was a total loss of around 55 ha of coastal ecosystems, including mangrove, creeklets, mudflats and sandy coasts. Also, almost 300 metres of shore area was eroded.

This was brought to the fore in a latest study done by Pune-based organization Srushti Conservation Foundation (SCF). Carried out close to the mouth of Bankot Creek, which has a 1.5-kilometer-long beach area, the study was prompted by information shared by Devghar residents who claimed that the beach had been steadily eroding since the 1990s.

The researchers ran a preliminary analysis to determine the degree of erosion since the 1990s and assembled satellite datasets to look into the claim. “It was observed that the satellite-derived shoreline has now shifted 300-500 meters towards land. Also, it was clear that mangrove and Casuarina plantation was not able to withstand the loss of sediment and eventually got uprooted,” said Deepak Apte, managing director of SCF.

The expert added that climate change related sea-level rise will further worsen the situation and the government should commission a study to seek solutions to deal with the changing seascape.

At present, the Casuarina plantation extends along the north-south belt on Devghar beach. However as per the study, the beach-side plantation was found to be getting destroyed due to continuous loss of sediment resulting in the erosion of the shore, along with change in sediment profile from a clay-silty dominated seascape to coarse sand dominated seascape.

The satellite images further revealed that mangroves were distributed unevenly in this patch. In the central part of this patch, dead mangroves were observed on a large scale. “The shoreline is changing steadily in several parts of the state and there is a need for a systematic assessment of the same,” the study stated.

The area of Devghar beach is near the Bankot creek which has been witnessing sand mining. Though the impact of sand mining is reportedly unclear at this point of time on the erosion at Devghar region, unregulated sand mining is facilitating erosion in several areas along the state coastline.

“For example, various stretches between Alibaug and Mandwa have witnessed illegal sand mining eroding beaches completely. While on one side sea level is increasing, on the other side, sand mining on beaches is flattening natural shore gradient facilitating coastal inundation,” said Apte.

SOLUTIONS

State to develop shore management policy by using cutting-edge science

Launch community-based climate resilience, adaptation and awareness programme

Scientific management across creek areas to maintain optimal depth and water level

Review efficacy of sea walls and its impact on shore erosion in nearby areas