24 October 2022 – The Hindu

Coastal Erosion

Background:

• Severe winds, drainage, wave action, wave currents, and tidal currents all contribute to coastal erosion by wearing away land and removing beach sediments. The study of coastal erosion and sediment redistribution is known as coastal morphodynamics. The causes are corrosion, hydraulic action, or abrasion.
• Coastal erosion can be classed as either a rapid-onset or a slow-onset hazard (happens in a matter of days to weeks) (occurring over many years, or decades to centuries).
• In India, beaches and shorelines serve a range of functions, including functioning as a seaport for marine commerce, providing space for residential and commercial buildings, and giving recreational opportunities.
• Coastal development activities have increased in recent decades, and this trend is expected to continue. Like any other marine country, India’s long peninsular territory is constantly combating erosion.
• Coastal development projects are routinely undertaken without a comprehensive understanding of the coast’s dynamics. Local communities suffer long-term, and in the worst-case scenarios, irreversible damage.
• High, medium, and low coastal erosion damage 40% of India’s coastline, according to the Ministry of Environment, Forest and Climate Change (MOEFCC).
• Analysis

What is the importance of preventing coastal erosion:

• The coastal zones where land and water meet are extremely dynamic and sensitive due to the ongoing interaction of marine and coastal ecosystems.
• The ecology of these areas is made up of mangroves, water bodies, seaweed, coral reefs, fisheries, and other marine life, as well as various coastal and marine flora.
• These ecosystems shield the region from saline winds, cyclones, tsunami waves, and other natural disasters, promote carbon sequestration and biodiversity, and provide raw materials for a wide range of manufacturing activities. As a result, combating coastal erosion is a risky proposition for us.

Causes of Coastal Erosion:

• Wave energy is assumed to be the primary cause of coastal erosion.
• Natural hazards such as cyclones, seawater thermal expansion, storm surges, and tsunamis are all hampered by climate change-induced melting of continental glaciers and ice sheets.
• Strong littoral drift, which results in sand movement, is one of the most major causes of coastal erosion.
• Dredging, sand mining, and coral mining have all contributed to coastal erosion, resulting in sediment shortages, changes in sea depth, and wave refraction.
• By restricting the flow of sediments from river estuaries, fishing harbours and dams built in the catchment basin of rivers and ports have started coastal erosion.
• Heavy rain can increase soil saturation, lowering the soil’s shear strength and increasing the danger of slope failure as a result (landslides).

The State of Coastal Erosion in India:

• The Ministry of Earth Sciences, which monitors shoreline changes along the Indian coast, claims that
• The Bay of Bengal erodes around 89 percent of Andaman and Nicobar Island’s shoreline.
• Goa has the highest percentage of stable shoreline.

Coastal Erosion in Different Parts of the World:

• According to a study published in the scientific journal Nature Climate Change, climate change poses an existential threat to the world’s sandy beaches, with up to half of them disappearing by the end of the century.
• Certain coastlines may be unrecognisable by 2050, according to the analysis, with 14 percent to 15% of them at risk of catastrophic erosion.
• Tamil Nadu has the most recent shoreline, with land added to 62 percent of its coastline.

Example:

• A huge section of the beach between Someshwara Rudrapade and Uchila appears to have been wiped away.
• Hundreds of people in the coastal Kerala towns of Aliyarpalli, Marakkadavu, Murinjazhi, Puthuponnani, Azhikkal, Veliyankode, Thannithura, Palappetty, and Kappirikkad have fled their houses due to fears of sea erosion.
• The Indian coastline stretches about 7517 kilometres, encompassing the beaches of the Bay of Bengal’s Andaman and Nicobar Islands and the Arabian Sea’s Lakshadweep Islands.
• The Indian mainland’s 6100 km of coastline is surrounded by the Arabian Sea in the west, the Bay of Bengal in the east, and the Indian Ocean in the south.
• Kandla, Mumbai, Navasheva, Mangalore, Cochin, Chennai, Tuticorin, Vishakapatnam, and Paradip are just a few of the prominent ports along India’s long coastline.

What led the Eastern shore to deteriorate at a faster rate than the Western:

• The eastern coast of India endured more soil erosion than the western coast due to the harsher waters of the Bay of Bengal compared to the Arabian Sea.
• Because the eastern coast receives a lot of rain, the seas are turbulent for much of the year.
• The Northeast Monsoon (October to December) affects the eastern coast in addition to the Southwest Monsoon (June to September), delivering rain to coastal Andhra Pradesh and Tamil Nadu.
• Compared to the western shore, which has been relatively stable over the previous three decades, the eastern shoreline has seen increased erosion as a result of recurrent cyclonic activity from the Bay of Bengal.

The effects of coastal erosion include:

Instantaneous Effects:

• The removal of small islands is underway.
• Beach sediments are disappearing.
• Existing flora and fauna habitats along the coast are being destroyed.
• Coastal defences such as sea walls, revetments, bulkheads, and other structures are degraded or destroyed.
• Agricultural land is disappearing.
• Deposition of sediment on productive fields.
• Jetties are deteriorating and being demolished.
• Building foundations, sewage tanks, water tanks, and boat-launching facilities have all been damaged or destroyed.
• The failure of shoreline, bridge, road, and railway foundations has hampered communications.

Other Effects:

• Those that rely on coastal areas for their livelihood would lose money.
• The amount of protection provided against future storms will be reduced.
• The formation of unstable cliff slopes.
• Pollution on the beach as a result of blocked sewer systems.
• Suffocation and saline water invasion lurk behind breached defences.
• As a result of breaching defences, land areas were flooded.
• Drinking Water Scarcity Control Methods

Measures for preventing coastal erosion:

• Hard-erosion control methods provide a long-term solution, whilst soft-erosion control methods provide a temporary one.
• Seawalls and groynes are examples of semi-permanent infrastructure. As a result of normal wear and tear, these buildings will need to be restored or replaced. The average life lifetime of a seawall is 50–100 years, while the average life span of a groyne is 30–40 years. Because of their relative permanence, these structures are regarded to be the last answer to erosion.
• Erosion controls for soft materials
• Soft erosion strategies are temporary solutions for decreasing the effects of erosion. Sandbags and beach nourishment, for example, are not intended to be long-term or permanent solutions.
• Another technique, beach scraping or beach bulldozing, can be used to create an artificial dune in front of a building or to protect a building’s foundation.

Relocation:

• The relocation of infrastructure or houses away from the coast is referred to as a managed retreat. Both absolute and relative sea-level rise and erosion are taken into account when rebuilding.
• Increased flora near the coast, which is important for slope stability and beach protection.
• Using geosynthetic tubes, which may be found all along Odisha’s coast.
• To keep drifting at bay, low walls or barriers called groynes are placed out into the sea.
• Making advantage of local people’s indigenous knowledge before making decisions about coastal development projects.

Conclusion:

• Approximately a third of the country’s coastline has been substantially deteriorated, according to the National Centre for Coastal Research (NCCR). We are losing more coastal lands as a result of climate change. The government and the people must integrate traditional wisdom with scientific approaches to mitigate the effects of climate change on our coastal areas.