- Coastal erosion is the loss or displacement of land, or the long-term removal of sediment and rocks along the coastline due to the action of waves, currents, tides, wind-driven water, waterborne ice, or other impacts of storms.
- According to the IPCC, sea level rise caused by climate change will increase coastal erosion worldwide, significantly changing the coasts and low-lying coastal areas.
- Corrosion or chemical weathering occurs when the sea’s pH (anything below pH 7.0) corrodes rocks on a cliff face.
- Abrasion, also known as corrasion, occurs when waves break on cliff faces and slowly erode it.
- Attrition occurs when waves cause loose pieces of rock debris to collide with each other, grinding and chipping each other, progressively becoming smaller, smoother and rounder.
- Hydraulic action occurs when waves striking a cliff face compress air in cracks on the cliff face. This exerts pressure on the surrounding rock, and can progressively splinter and remove pieces.
Factors that cause coastal erosion
- Natural causes
- Natural factors influencing coastal erosion are waves, winds, tides, near-shore currents, storms, sea level rise, etc.
- An increasing sea level will promote shoreline erosion. Such erosion is higher in the littoral coasts consisting of finer sediments, as compared to coasts consisting of coarser sediments.
- Subsidence is a regional phenomenon that lowers the surface area in a specific region. It also contributes to coastal erosion, the rate may vary as per the factor causing this subsidence.
- Catastrophic events like severe storms, tidal surges, and cyclones cause the sea level to rise to abnormal heights and cause severe erosion.
- Anthropogenic factors
- The mining of sand and gravel along beaches and in the surf zone will cause erosion by depleting the shore of its sediment resources.
- Dredging of harbours, navigation channels disturbs sediment equilibrium.
- The removal mangroves causes exposure of the low-energy shorelines to the increased energy and reduced sediment stability.
- 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.
- The Integrated Coastal Zone Management Plan aims to promote the management of the coast using an integrated approach, taking into considerationall aspects of the coastal zone, including geographical and political boundaries, to achieve sustainability.
- The Coastal Regulation Zone (CRZ) Notification were issued in 1991 under the Environmental Protection Act, 1986, by the Ministry of Environment, Forest and Climate Change (MoEFCC) aims to regulate activities in coastal areas.
Coastal regulation zone
- The coastal regulation zone (CRZ) includes creeks, seas, bays, rivers, and backwaters that are impacted by tides up to 500 metres from the high tide line (HTL) and the land area between the low tide line (LTL) and the high tide line.
- CRZ Classification
- CRZ-I contains environmentally sensitive areas where no building is permitted except for operations related to nuclear power plants and defence.
- CRZ-II contains designated urban areas that are heavily developed, where construction operations are only permitted on the landward side.
- CRZ-III consists generally of undisturbed areas, primarily in rural areas. No new building construction is authorised in this zone but repairs can be done on existing structures. Dwelling units are permitted on plots located between 200 and 500 metres from the high tide line.
- CRZ-IV encompasses the water region between the low tide line and 12 nautical miles seaward. Except for fishing and associated activities, this zone will govern all activities involving the sea and tidal water.
Why in news?
- PIL plea wants Tamil Nadu, to identify areas prone to coastal erosion.