Data on Climate Change an Effective Weapon in Fighting India’s Coastal Erosion

A stabilized beach in the southern Indian state of Karnataka, following coastal protection measures. Photo: Public Works, Ports, and Inland Water Transport Department, Karnataka.
A stabilized beach in the southern Indian state of Karnataka, following coastal protection measures. Photo: Public Works, Ports, and Inland Water Transport Department, Karnataka.

By Rajesh Yadav

Effective and planned shoreline management would trigger activities for tourism, and support development of ocean and beach landscape, conserve biodiversity along with coastal people’s livelihood.

Puducherry, a small town on India’s east coast known for its beautiful beaches, is a popular destination for tourists. In the 1990s, the Puducherry beach began to erode dramatically after construction of a port. Within a few years, nearly 8 kilometers of beach used by residents and tourists disappeared despite raising of a rubble seawall to arrest erosion.

A combination of human and natural causes of erosion have lost an estimated 57% of Puducherry’s coastline over the years.  Much of the rest of India’s vast coastline of 7,500 kilometers spread almost equally on the east and west of the peninsula is also threatened. India lost about one third of its coastline to erosion between 1990 and 2016, putting at risk more than 560 million people living in coastal areas.

Threats to India’s coastline are set to exacerbate with climate change, causing higher sea levels, unpredictable precipitation and frequent storms. These hazards will threaten a large chunk of India’s coastal population living in low-lying flood-prone areas, as well as commercially important centers such as Mumbai, Chennai, and Kolkata.

Effective measures are needed urgently to build resilience of India’s coastline, 45% of which is estimated to require protection.

Current policies on shoreline management and planning in India, however, still do not explicitly account for climate change-related risks and vulnerabilities. This is partly due to the lack of a database and quantifiable evidence on potential impact scenarios under climate change. Such data, if made available, would help policy makers design the best solutions for sustainable coastal protection.

A recent study  financed by the Global Environment Facility and administered by ADB for the Central Water Commission in India’s Ministry of Water Resources, strives to bridge some of these shortfalls in research and planning in coastal management by prescribing a set of regulatory and intervention guidelines.

For the first time, a holistic approach is adopted to address the social, economic, management, scientific, engineering and environmental dimensions to protect and mitigate India’s coastline from climate-induced impacts.

Leading Indian research and technical institutes collaborated to analyze and estimate the potential impact of climate change on important climatic parameters. These include climate change projections   on storm surges, wave patterns, and sea-level trends for each coastal state and for islands in India.

About 1,400 coastal locations were chosen for climate data simulation for a 100-year period.

  Some alarming findings in India’s coastal areas

Odisha, on the east coast, and Gujarat, on the west coast, the two states that faced severe cyclones this year, are projected to be hit by even more intense cyclones in the future, along with Andhra Pradesh. The simulations for an extreme climate change scenario suggest a rise in maximum water level up to 8.5 meters along Gujarat coast and a surge up to 11 meters on the Odisha coast for the projected storms.

The southern state of Kerala, which faced its worst floods in 2018 due to unusually high precipitation, will be prone to even higher rainfall events. The wave studies indicate 7-11% increase in wind speeds along India’s coastline by the turn of the next century as the result of increased greenhouse gas emissions.

An overall conclusion of the study is that ‘the beach is the best form of coastal protection.’ This is demonstrated through the concept of an ‘environmental softness ladder’ that distinguishes the potential environmental effects of sand-based solutions from construction-based coastal interventions. All rungs represent stages from softest to the hardest solution – progressing from dune care, nourishment, offshore reefs, and breakwaters to groynes and seawalls.

The idea is to encourage use of softest possible solutions after careful consideration and ruling out options at the lower rung of the ladder, before proceeding to adopt harder protection measures which can potentially disrupt the beach, natural sediment movement and environment.

Certain coastal dynamics, however, necessitate using a combination of both hard and soft measures or hybrid methods combing beach nourishment with structures.

A successful example of this approach is seen in an ongoing ADB project in the coastal belt in Mangalore abutting the Arabian sea in the southern state of Karnataka. Innovative technologies in designing offshore reefs, groynes, and breakwaters were combined with sand-nourishing measures to arrest erosion and protect coastal communities along the shoreline. These efforts resulted in recovering nearly 2 kilometers of the lost beach with increased width up to 70 meters, that has spurred small businesses on the beach to cater to increasing tourist arrivals. More encouragingly, the protection infrastructure stood firm during the extreme weather event – Cyclone Ocki – that struck the region in 2017, confirming the efficacy of these measures.

Engineering solutions, though, are only one aspect of the coastal protection exercise. These would work best in tandem with a robust regulatory framework. The study takes care of this aspect by examining gaps in the enforcement of current regulations in India’s Coastal Regulation Zone. The guidelines emphasize improving administrative processes, undertaking globally-accepted cost-benefit and life-cycle costing, enforcing land use regulations, controlling sand mining and preparing robust environment impact assessment reports. Conserving beaches, and sand dunes and new structures in the Coastal Regulation Zone should be above the minimum floor level to allow for climate change projections of storm surge, waves and sea level rise.

One important recommendation is for preparing comprehensive shoreline management plans for coastal protection. These plans could be made for larger and smaller sections of the coastline - explained through the concept of sediment cell that is a self-contained localized section of coastline in terms of movement of sand. For shoreline management plan formulation, a large-scale assessment of risks from coastal processes, including from climate change, is envisaged. These would include collection of coastal data, shoreline assessments, stakeholder engagement, wave and sediment transport modelling, and an assessment of the government’s tourism, industrial and port policies.

For any such plans to succeed, better coordination among different agencies and inclusion of multidisciplinary experts would be required.

Effective and planned shoreline management would trigger activities for tourism, and support development of ocean and beach landscape, conserve biodiversity along with coastal people’s livelihood.

The guidelines recognize the links between economic, physical, social and governmental complexity in handling climate change. The concept promoted is that effective solutions are possible only when all facets are improved simultaneously. Practical solutions to inhibit coastal erosion and sustain life and livelihood are presented with information from historical case studies, modern scientific knowledge and best global practices. While the guidelines are focused on India, the document provides useful assistance to all countries with shorelines exposed to climate change. An unscientific design cannot be made climate resilient. To save the beaches and coasts of India from potential climate change impacts, coastal planning will need to be strategic rather than ad hoc. That is the key message for coastal planners.