COASTAL VULNERABILITY INDEX

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• Recently, the Ministry of Earth Sciences informed the Lok Sabha that of the 6,907.18 km long Indian coastline of the mainland, a significant area is under varying degrees of Coastal erosion.
• About 34% is under varying degrees of erosion, while 26% of the coastline is of an accreting nature, and the remaining 40% is in a stable state.
• West Bengal suffered erosion along about 60.5% of the coast (323.07 km) over the period from 1990 to 2018. This is followed by Kerala (46.4%) and Tamil Nadu (42.7%) respectively.
• Earlier, the Indian National Centre for Ocean Information Services (INCOIS) had prepared and published an atlas of Coastal Vulnerability Index (CVI) maps for the entire coastline of India.

Coastal Erosion

• Coastal erosion is the process by which local sea level rise, strong wave action, and coastal flooding wear down or carry away rocks, soils, and/or sands along the coast.
• Erosion and Accretion: Erosion and accretion are complementary to each other. If the sand and sediments have drifted from one side, it must accumulate somewhere else.
• Soil erosion is the loss of land and human habitation as sea water washes off regions of soil along the coastline.
• Soil accretion, on the other hand, results in an increase in the land area.
• Recreational activities (sun bathing, picnicking, swimming, surfing, fishing, boating, diving, etc.) may be affected if existing beaches are reduced in width or disappear altogether. Also, there can be an impact on livelihoods of coastal communities.
• Coastal habitats such as Mangroves, Coral Reefs and lagoons are recognized as the best defence against sea storms and erosion, deflecting and absorbing much of the energy of sea storms. Therefore, it is important to maintain these natural habitats for shore protection as well as for environmental conservation.

Factors causing Coastal Erosion

• Wave energy is considered to be the primary reason for coastal erosion.
• Natural hazards like cyclones, thermal expansion of seawater, storm surges, tsunami etc due to the melting of continental glaciers and ice sheets as a result of climate change hamper the natural rhythm and precipitate erosion.
• Strong littoral drift resulting in sand movement can also be considered as one of the major reasons for coastal erosion.
• Littoral drift means the natural movement of sediment along marine or lake shorelines by wave action in response to prevailing winds.
• Dredging, sand mining and coral mining have contributed to coastal erosion causing sediment deficit, modification of water depth leading to longshore drift and altered wave refraction.
• Coastal erosion has been sparked by fishing harbours and dams constructed in the catchment area of rivers and ports reducing the flow of sediments from river estuaries.

 Methods for Coastal Protection

1. Artificial Beach Nourishment
2. Protective Structures: Seawalls, Revetments.
3. Structures to Trap Sediment Movement.
4. Combination of Artificial Beach Nourishment & Structures.
5. Control of Beach Groundwater Table or Beach Dewatering System.
6. Vegetation Planting.
7. Use of Geo-synthetic Tubes / Bags.

Way Forward

The XVth Finance Commission had suggested, The National Disaster Management Authority (NDMA) and/or Ministry of Home Affairs may develop suitable norms for mitigation measures to prevent erosion and both the Union and the State Governments develop a policy to deal with the extensive displacement of people caused by coastal and river erosion.

SOURCE: THE HINDU,THE ECONOMIC TIMES,MINT