New Delhi, According to a study by the Indian Space Research Organization (ISRO), India has lost over 3,680 hectares of land to coastal erosion over a span of 10 years, with West Bengal and Gujarat bearing the brunt.
Research by ISRO’s Space Applications Centre, Ahmedabad, on the comprehensive data available between 2004-06 and 2014-16 shows that 15 per cent of India’s coastline – about 1,144 km – is undergoing erosion. Meanwhile, 14 percent of India’s coastline, or 1,084 km, is growing.
The world’s coastlines are constantly changing due to natural processes such as coastal erosion and accretion, as well as human activities affecting sediment transport.
However, anticipated sea level rise, increased wave activity, and a projected increase in the frequency and intensity of tropical cyclones due to climate change are expected to lead to more rapid and severe shoreline changes in the near future, the researchers said in the report. Soon to be published in peer-reviewed journal current science,
Coastal erosion means acres are disappearing. This can lead to a loss of habitat for local fauna and flora, and make people living in coastal areas vulnerable – their land disappears, the closer they are to the sea.
Accretion is the process of return of coastal sediment to the visible part of a beach or foreshore after a submergence event. A permanent beach or foreshore often undergoes cycles of subsidence during rough weather and accretion during calm periods.
Accretion can be profitable in some cases, as there is an increase in land area. But it can harm marine life – such as sea creatures suddenly finding their waters shallower, or turtle habitats moved away from shorelines.
According to the research team’s estimates, India gained 4,042 hectares of coastal area between 2004-06 and 2014-16. Although there is a net gain in total coastal area (due to sediment/sand deposition), the stretch under erosion is greater than the increased shoreline.
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changing coasts
According to a 2020 European StudyThe world is set to lose half of its sandy beaches by the end of the century due to coastal erosion driven by rising sea levels.
Coastal environments naturally maintain a balance in the supply of sediment along the coast – carrying sediments away and then bringing them back to shore in cycles – but during monsoons, cyclones and human activities such as coastal construction and dam building, high Wave activity can disrupt it. equilibrium, leading to shoreline change.
Monitoring of shoreline changes helps in planning measures to carry out sustainable development activities along the coastal zone.
Mapping of HTA with ISRO satellite images
The researchers considered the High Tide Line (HTL) as the beach. Using images from LISS-IV sensors on ISRO’s Resourcesat-1 and 2 satellites, the team was able to map the HTL of Indian coastal states with a spatial resolution of 5.8 m, corresponding to the time frame of 2004-06 and 2014-16 Was.
For different states, the HTL is represented by different landscape indicators – such as mangroves, cliffs, seawalls or permanent vegetation lines. The team used a digitization technique to map the coastlines for each state.
The team found that the Andaman and Nicobar Islands have the longest coastline (231 km) and the longest coastline (256 km). Erosion is lowest in the Lakshadweep Islands (12 km), and Goa has the shortest length of coastline (7 km).
The percentage of shoreline erosion is highest in West Bengal (36 percent), followed by Odisha (32 percent), Kerala (23 percent) and Andhra Pradesh (23 percent). Rest of the maritime states have less than 20 per cent coastline with Lakshadweep recording the minimum (8 per cent).
Andhra has the highest percentage of rising coastline (26 percent), followed by Tamil Nadu, Odisha and West Bengal (22 percent each) and Kerala (21 percent).
The percentage of stable coastline is highest for Gujarat (87 percent), followed by Lakshadweep (82 percent). For Maharashtra and Goa, this figure is 80 per cent.
The shoreline varies more on the east coast
The shoreline change is more on the east coast of the Indian peninsula as compared to the west coast.
West Bengal, Gujarat, Odisha and Goa have suffered a net loss of coastal area due to erosion during the 10 years. The loss is greatest for West Bengal (252 ha).
Meanwhile, Tamil Nadu, Maharashtra, Karnataka, Kerala, Andhra Pradesh and Lakshadweep have gained coastal land. This gain is the largest for the Andaman and Nicobar Islands (524 ha).
“Since coastal erosion is a serious threat to both the ecology and the economy of the country, The shoreline change inventory is the primary information needed for coastal planning. development activities,” the researchers said in the report.
“The Shoreline Change Atlas reflects changes in the shoreline. However, planning for coastal developmental activities should also include an assessment of anticipated shoreline changes under climate change scenarios,” they write.
(Edited by Geetalakshmi Ramanathan)
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