03 September 2024 – The Hindu

Coastal Erosion – A Growing Threat to India’s Shorelines

Why in News?

• A recent study has highlighted the growing threat of coastal erosion to the livelihood of fishing communities and other residents along the coast of Tamil Nadu. This study reveals a concerning trend, where almost 43% of Tamil Nadu’s coastline is being eroded, resulting in the loss of over 4,450 acres of land. The rate of erosion on the east coast is particularly alarming, with land being eroded at an average rate of 3 meters per year, while the west coast is losing 2.5 meters annually. Ironically, development projects designed to stimulate economic growth and mitigate sea erosion are contributing to the problem by altering natural shorelines.

Key Findings of the Study Regarding Tamil Nadu Coast:

• Wind and Current Dynamics: For about eight months each year, wind and sea currents along the Tamil Nadu coast move from south to north, transporting sand along the coast. During the northeast monsoon, these currents reverse direction.
• Impact of Coastal Structures: The construction of coastal structures like ports, breakwaters, or groynes disrupts the natural movement of sand, causing it to accumulate on one side while leading to erosion on the other. This disruption accelerates coastal erosion, pushing waves further inland and increasing the vulnerability of coastal areas.

Understanding Coastal Erosion:

• What is Coastal Erosion?: Coastal erosion is the process by which the sea gradually wears away the land, typically due to strong wave action, rising sea levels, and coastal flooding. It involves the breakdown and removal of rocks, soils, and sands along the coastline.

Processes of Coastal Erosion:

• Corrasion: Strong waves throw beach material like pebbles at the base of a cliff, gradually breaking it down and creating a wave-cut notch.
• Abrasion: Waves carrying sand and larger fragments wear away the base of a cliff or headland, functioning like a natural sandpaper.
• Hydraulic Action: Waves compress air in cracks and joints in the cliff, and when the wave recedes, the trapped air bursts out, causing chunks of the cliff to break off.
• Attrition: Waves cause rocks and pebbles to collide and break into smaller pieces over time.

Causes of Coastal Erosion:

• Wave Action: Powerful waves, through processes like abrasion, corrasion, and hydraulic action, can erode coastlines. For instance, the cliffs of Dover in England are being eroded by the English Channel’s waves.
• Tidal Influence: Areas with significant tidal ranges, such as the Bay of Fundy in Canada, experience significant erosion due to the extreme tides.
• Wind and Sea Currents: Gradual and long-term erosion can result from consistent wind and sea currents. In Tamil Nadu, for example, the south-to-north movement of sand along the coast is a key factor in erosion.
• Human-Made Structures: Coastal infrastructure like ports, breakwaters, and groynes disrupt the natural flow of sand, causing erosion on the down-current side and accumulation on the up-current side. Groynes, in particular, are low-lying structures meant to trap sediment but can exacerbate erosion.
• Development Projects: Infrastructure projects meant to boost economic growth can alter shorelines and worsen erosion. For instance, land reclamation efforts in Mumbai have led to erosion in nearby coastal areas.
• Port Expansion: The expansion of ports and harbors often leads to sediment accumulation on one side of the structure and increased erosion on the other. The Ennore Port and Adani Kattupalli Port in Tamil Nadu are examples where such development has contributed to coastal erosion.

Coastline of India:

• Length: India has a coastline of 7,516.6 km, including 6,100 km of mainland coast and 1,197 km of island coastline.
• Longest Coastline by State: Gujarat has the longest coastline among Indian states at 1,214.7 km, followed by Andhra Pradesh (973.7 km) and Tamil Nadu (906.9 km).
• Longest Coastline by UT: The Andaman & Nicobar Islands boast the longest coastline among Union Territories, with a total of 1,962 km.
• Coastal Characteristics: The Coromandel coast in Tamil Nadu is a coast of emergence, while the Konkan coast, covering Maharashtra and Goa, is a coast of submergence.

Impacts of Coastal Erosion:

• Loss of Land: Coastal erosion leads to the loss of valuable land, affecting properties and infrastructure. For example, erosion along Chennai’s Marina Beach has led to significant land loss, affecting public spaces.
• Impact on Coastal Ecosystems: Erosion destroys crucial habitats like mangroves, salt marshes, and sand dunes, which are vital for various species. The Sundarbans in West Bengal have experienced significant mangrove loss due to erosion.
• Increased Flooding Risk: Erosion can reduce natural barriers against flooding, heightening the risk in vulnerable areas. In Kerala, erosion has exacerbated the impact of heavy rains and storms by increasing flood risks.
• Displacement of Communities: Erosion can displace entire communities, leading to social and economic upheaval. The Andaman and Nicobar Islands have seen communities forced to relocate due to land loss.
• Salt Water Intrusion: Erosion can lead to the salinization of agricultural lands, reducing their productivity. In Andhra Pradesh, saltwater intrusion has negatively impacted crop yields.
• Impact on Marine and Coastal Biodiversity: Coastal erosion can alter ecosystems and disrupt food chains. In the Lakshadweep Islands, marine ecosystem health has been compromised due to erosion.

Preventive Measures Against Coastal Erosion:

• Vegetation: Planting seagrass and other coastal vegetation can stabilize sand and prevent erosion.
• Beach Nourishment: Nature-based solutions, such as planting mangroves, help shorelines absorb and dissipate storm energy without interfering with natural coastal processes.
• Coastal Restoration: Restoring habitats like wetlands benefits marine and coastal species by providing important nursery grounds, contributing to carbon sequestration, and restoring open spaces.
• Regulatory Measures: Implementing zoning laws, building codes, and maintaining a minimum distance from shorelines for new constructions can help regulate coastal development and mitigate erosion.

Government Initiatives to Combat Coastal Erosion:

• Shoreline Mapping System: The National Centre for Coastal Research (NCCR) has mapped the Indian coastline, finding that 33.6% is vulnerable to erosion, 26.9% is accreting, and 39.6% is stable.
• Hazard Line Definition: The Ministry of Environment, Forest & Climate Change (MoEFCC) has defined a hazard line to indicate shoreline changes and sea-level rise, aiding disaster management and adaptive planning in coastal states and UTs.
• Coastal Regulation Zone (CRZ) Notification 2019: This notification allows for erosion control measures and establishes No Development Zones (NDZ) to protect coastlines from encroachment and erosion.
• Coastal Zone Management Plans (CZMP): Following a National Green Tribunal (NGT) directive, States/UTs have been tasked with finalizing CZMPs, including mapping erosion-prone areas and preparing Shoreline Management Plans.
• National Strategy for Coastal Protection: MoEFCC has developed a national strategy and guidelines for coastal protection applicable to all Coastal States and UTs.
• Flood Management Scheme: Anti-sea erosion schemes are planned and executed by state governments with assistance from the Union Government in technical, advisory, and promotional capacities.
• Coastal Management Information System (CMIS): This system collects nearshore coastal data to aid in the planning, design, and maintenance of coastal protection structures. An experimental CMIS has been established at sites in Kerala, Tamil Nadu, and Puducherry.

Conclusion/Way Forward:

• Coastal erosion poses a significant threat to India’s coastlines, with both natural and human-induced factors accelerating shoreline degradation. The loss of habitats, displacement of communities, and increased flooding risks underscore the urgent need for effective management and protection strategies. Government initiatives, such as hazard lines, CRZ Notification 2019, and CMIS, play a crucial role in mitigating erosion and safeguarding coastal regions. Continuous monitoring, research, and the adoption of sustainable development practices are essential to preserve India’s coastal ecosystems and protect the livelihoods of those who depend on them.