Syllabus
GS Paper III – Conservation, environmental pollution and degradation, environmental impact assessment.
Context
A recent study has found that coastal erosion is endangering the livelihoods of fishers and other residents in coastal Tamil Nadu.
Coastal Erosion
Introduction
In Tamil Nadu, the natural movement of sand is disrupted by structures like ports and breakwaters, which block the south-to-north currents for most of the year and the reverse flow during the northeast monsoon. This disruption causes sand accumulation on one side and erosion on the other, accelerating coastal erosion and pushing waves further inland. Nearly 43% of Tamil Nadu’s coast is affected, with over 4,450 acres lost. Erosion rates are increasing by 3 meters per year on the east coast and 2.5 meters on the west. Development projects aimed at economic growth and erosion prevention are exacerbating the problem by altering the shoreline.
Coastal Erosion
- Coastal erosion occurs when the sea wears away the land, often due to strong waves breaking down the coast.
- It involves local sea level rise, strong wave action, and coastal flooding that wear down or carry away rocks, soils, and sands along the coast.
- Coastal erosion is a significant environmental hazard affecting India’s vast coastline, which spans approximately 7,500 kilometers.
- It is primarily caused by natural processes such as wave action, tides, and currents, but is exacerbated by human activities.
- Coastal erosion has far-reaching consequences on coastal communities, infrastructure, and ecosystems.
Processes of Coastal Erosion
- Corrasion: This process occurs when strong waves throw beach material like pebbles at the base of a cliff, gradually breaking it down and creating a wave-cut notch (a small, curved indent at the base of a cliff).
- Abrasion: This happens when waves, carrying sand and larger fragments, wear away the base of a cliff or headland. It’s similar to a sandpaper effect and is especially common during powerful storms.
- Hydraulic Action: This occurs when waves hit a cliff, compressing air in cracks and joints. When the wave pulls back, the trapped air rushes out explosively, causing chunks of the cliff to break off. Weathering weakens the cliff further, making this process more effective.
- Attrition: This process happens when waves cause rocks and pebbles to bump into each other and break up.
Causes of Coastal Erosion
- Waves: Powerful waves can erode coastlines through abrasion, corrasion, and hydraulic action. For example, the cliffs of Dover in England are being eroded by the constant action of the English Channel’s waves.
- Tides: High and low tides can affect the amount of erosion, particularly in areas with significant tidal ranges. For instance, the Bay of Fundy in Canada experiences extreme tides that can significantly erode coastlines.
- Wind and Sea Currents: These can cause gradual and long-term erosion. On the Tamil Nadu coast, for most of the year (eight months), wind and sea currents move from south to north, carrying sand along the coast. During the northeast monsoon (four months), this direction reverses.
- Hard Structures: Ports, breakwaters, and groynes interfere with the natural movement of sand, causing erosion on the down-current side and sand accumulation on the up-current side. Groynes are low-lying wood or concrete structures designed to trap sediment and dissipate wave energy.
- Development Projects: Infrastructure projects aimed at boosting economic growth are exacerbating erosion by altering the shoreline. For example, land reclamation in places like Mumbai causes erosion in nearby coastal regions.
- Port Expansion: When ports and harbours are expanded, structures like breakwaters and jetties block the natural movement of sand and sediment along the coast. This can lead to sediment accumulation on one side of the structure and increased erosion on the other side. For instance, Ennore Port and the Adani Kattupalli Port in Tamil Nadu.
Impacts of Coastal Erosion
- Loss of Land: Erosion can lead to the loss of valuable coastal land, affecting property and infrastructure. For example, the loss of land along the Marina Beach area in Chennai has severely affected property and public spaces.
- Impact on Coastal Ecosystems: Erosion can destroy habitats such as mangroves, salt marshes, and sand dunes, which are crucial for various species. For instance, in the Sundarbans region of West Bengal, erosion has led to the loss of mangrove forests.
- Flooding Risk: Erosion can reduce the natural barriers that protect coastal areas from flooding. In coastal regions of Kerala, erosion has increased the risk of flooding, affecting low-lying areas and exacerbating the impacts of heavy rains and storms.
- Displacement of Communities: Erosion can force communities to relocate, leading to social and economic disruption. For example, coastal erosion in the Andaman and Nicobar Islands has led to the displacement of local communities, particularly on smaller islands where land loss is more pronounced.
- Salt Water Intrusion: Coastal erosion can lead to the salinisation of agricultural land, reducing crop yields. In Andhra Pradesh, saltwater intrusion has negatively affected crop yields and reduced the productivity of farmland.
- Impact on Marine and Coastal Biodiversity: Coastal erosion can alter ecosystems and food chains. For instance, it has hampered the health of marine ecosystems in the Lakshadweep Islands.
Government Initiatives to combat Coastal Erosion
- Shoreline Mapping System: The National Centre for Coastal Research (NCCR) observed that 33.6% of the Indian coastline is vulnerable to erosion, 26.9% is under accretion (growing), and 39.6% is in a stable state.
- Hazard Line: The Ministry of Environment, Forest & Climate Change (MoEFCC) has defined the hazard line to indicate shoreline changes and sea level rise. It is used for disaster management, adaptive planning, and mitigation measures in Coastal States/UTs.
- Coastal Regulation Zone (CRZ) Notification 2019: The CRZ Notification 2019 permits erosion control measures and establishes No Development Zones (NDZ) to protect the coastline from encroachment and erosion.
- Coastal Zone Management Plans (CZMP): Following a National Green Tribunal (NGT) order, States/UTs have been asked to finalize CZMPs, including mapping of erosion-prone areas and preparing Shoreline Management Plans.
- National Strategy for Coastal Protection: The MoEFCC has developed a national strategy and guidelines for coastal protection for all Coastal States and UTs.
- Flood Management Scheme: Anti-sea erosion schemes are planned and executed by State Governments with Union Government assistance in technical, advisory, catalytic, and promotional capacities.
- Coastal Management Information System (CMIS): The CMIS collects nearshore coastal data for planning, designing, and maintaining coastal protection structures. An experimental CMIS was set up at three sites each in Kerala, Tamil Nadu, and Puducherry.
- Coastal Erosion Mitigation: Measures have been taken up at Puducherry and Chellanam in Kerala, helping in the restoration and protection of coastal areas. Technical support has been extended to coastal States in the design of coastal protection measures at vulnerable stretches and preparation of Shoreline Management Plans.
Measures to prevent Coastal Erosion
- Vegetation: Strategic planting of seagrass and other coastal plants helps prevent erosion. The roots of these plants help anchor the sand and ensure that it is not washed away.
- Beach Nourishment: Nature-based or “green infrastructure” protection measures enhance the natural ability of shorelines to absorb and dissipate storm energy without interfering with natural coastal processes. For example, planting mangroves to serve as a buffer against erosion.
- Coastal Restoration: This involves restoring habitats such as wetlands to benefit marine and coastal species by providing important nursery grounds. It also has environmental benefits like carbon sequestration and the restoration of open spaces.
- Regulatory Measures: Zoning laws, building codes, and maintaining a minimum distance from the shoreline for new buildings or infrastructure facilities help regulate coastal development.
Conclusion
Coastal erosion poses a significant threat to India’s coastlines, impacting the environment and local communities. Both natural and human factors exacerbate shoreline changes, resulting in habitat loss and affecting fishermen’s livelihoods. To address this, improved shoreline mapping and government initiatives, such as hazard lines and the CRZ Notification 2019, aim to manage and protect coastal areas. Ongoing efforts, including the Coastal Management Information System (CMIS), continue to enhance these protective strategies.
Reference: TH
Related PYQ
Coastal sand mining, whether legal or illegal, poses one of the biggest threats to our environment. Analyse the impact of sand mining along the Indian coasts, citing specific examples. (UPSC CSE – 2019 Mains)
Practice Question
Examine the threats posed by climate change and rising sea levels to India’s coastal ecosystem. [150 words]