INDIA’S COASTLINE UNDERWENT SEA EROSION

Recently, the National Centre for Coastal Research (NCCR) under the Ministry of Earth Science has published a report that said one-third of India’s coastline underwent sea erosion in 28 years.
As much as 32% of India’s coastline underwent sea erosion and 27% of it expanded between 1990 and 2018.

Important points:

The country’s coastline is 6,631.53 kilometres long which is surrounded by the Arabian Sea in the west, Bay of Bengal in the east, and the Indian Ocean in the south.
2,135.65 kilometres was subject to varying degrees of erosion and 1,760.06 km expanded during this period.
Nearly 2,700 km of the coastline is stable.
The long coastline of India is dotted with several major ports such as Kandla, Mumbai, Nhava Sheva, Mangalore, Cochin, Chennai, Tuticorin, Visakhapatnam, and Paradip.
60% of the coastline of West Bengal underwent erosion during the period followed by Puducherry (56%), Kerala and Tamil Nadu at 41% and 41%, respectively.

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 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.
However, if accretion happens in Deltas, Estuaries, and creeks, the soil will block the inflow of seawater into these areas which are breeding ground for several species of aquatic flora and fauna.
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:

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.
Heavy rainfall can enhance the saturation of soils, with high saturation leading to a reduction in the soil’s shear strength, and a corresponding increase in the chance of Slope Failure (landslides)

SOURCE: THE HINDU,THE ECONOMIC TIMES,MINT

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