Coastal Flooding: Risks and Mitigation

Context: In the wake of climate change, countries and communities across the world face dangerous consequences of coastal flooding. Most of the people at risk from coastal flooding live in Asia’s developing countries like India and China. Experiences show that in disaster management, prevention is always better than cure. In this context, let's look at the risks of coastal flooding and measures for its mitigation. 

Relevance:
Mains: GS III- Disaster and disaster management.

What is Disaster Mitigation?

Mitigation is the effort to reduce the loss of life and property by lessening the impact of disasters. In order for mitigation to be effective we need to take action now- before the next disaster- to reduce human and financial consequences later (analyzing risk, reducing risk, and insuring against risk).
In other words, disaster mitigation measures are those that eliminate or reduce the impacts and risks of hazards through proactive measures taken before an emergency or disaster occurs.

What is Coastal Flooding: 

• Coastal flooding occurs when normally dry, low-lying land is flooded by seawater.
• The extent of coastal flooding is a function of the elevation inland floodwaters penetrate which is controlled by the topography of the coastal land exposed to flooding.

The seawater can flood the land via several different paths:

1. Direct flooding– where the sea height exceeds the elevation of the land, often where waves have not built up a natural barrier such as a dune system.
2. Overtopping of a barrier– the barrier may be natural or human-engineered and overtopping occurs due to swelling conditions during a storm or high tides often on open stretches of the coast. The height of the waves exceeds the height of the barrier and water flows over the top of the barrier to flood the land behind it. Overtopping can result in high velocity flows that can erode significant amounts of the land surface which can undermine defense structures.
3. Breaching of a barrier– again the barrier may be natural (sand dune) or human-engineered (sea wall), and breaching occurs on open coasts exposed to large waves. Breaching is where the barrier is broken down or destroyed by waves allowing the seawater to extend inland and flood the areas.

The causes of coastal flooding are storm and storm surges, sea-level rise, tsunami, etc. However, different estimates show that the rise in sea levels due to climate change poses one of the biggest causes of coastal flooding. 

• The Intergovernmental Panel on Climate Change (IPCC) estimate global mean a sea-level rise from 1990 to 2100 to be between nine and eighty-eight centimeters.
• It is also predicted that with climate change there will be an increase in the intensity and frequency of storm events such as hurricanes.
• This suggests that coastal flooding from storm surges will become more frequent with sea-level rise.
• A rise in sea level alone threatens increased levels of flooding and permanent inundation of low-lying land as sea level simply may exceed the land elevation.
• This, therefore, indicates that coastal flooding associated with sea-level rise will become a significant issue in the next 100 years especially as human populations continue to grow and occupy the coastal zone.

World's Vulnerability to coastal flooding:

• By 2050, in a scenario that limits warming to 2°C above average pre-industrial temperatures, about 150 million people worldwide will be permanently below the high tide line along the coast and, by 2100, the numbers will rise to 360 million people.
• While the above numbers are based on a moderate sea-level rise scenario, if carbon emissions rise sharply or ice sheets melt faster, then 640 million people will be at risk by 2100.
• The new estimates indicate that about a billion people reside on land along the coast going up to an elevation of 10 meters (the low elevation coastal zone) and the bulk of them, more than two thirds, are below the five-meter elevation.
• Most of the people found to be at risk from coastal events live in Asia- residing in countries like China, Bangladesh, India, Vietnam, Indonesia, Thailand, the Philippines, and Japan.  Very large fractions of coastal populations in these countries will be vulnerable.
• Other than Asia and the Netherlands, there are 20 countries, 13 of which are small island nations, in which more than a tenth of their population are expected to reside below the high tide line by 2100, and this is with deep cuts to emissions.
• Coastal cities, such as Alexandria, Ho Chi Minh City, Basra, and Shanghai are among the most vulnerable and large portions of Mumbai and Kolkata will be fully submerged by 2050.

India's Vulnerability to coastal flooding:

• India is the third worst-affected country due to climate-induced natural disasters.
• The country’s coastal regions, in particular, are highly vulnerable because of rapid urbanization, high population densities and related economic activities such as agriculture, aquaculture, tourism, industries, and trade.
• The 7,517-km-long coastline is home to 260 million people or one- third of India’s population, who live in low-lying areas within 50 km of the sea coast and are perennially exposed to climate variabilities and extreme weather events.
• In recent years, India’s coastal regions have become more vulnerable to multiple risks related to climate change.
  • Intense and more frequent cyclones such as the recent Fani, Gaja, and Hudhud as well as severe floods have caused massive devastation to the country’s coastal states.
• By 2050, 36 million Indians may be affected by flooding and inundation due to sea-level rise.
• Recent estimates show that the increase in sea level in the Indian Ocean is at the rate of 5-6 cm per decade. At this rate, the densely populated low-lying cities like Mumbai and Kolkata are at greater risk.
• Warming oceans leading to sea-level rise provide a source of thermal expansion of seawater, contributing to more intense and frequent storm surges and cyclones in the coastal regions.
• Between 1877-2005, a total of 283 cyclones made landfall in India’s coastal regions; 106 of them were severe cyclones that occurred in a 50-km-wide strip on the east coast, and 35 were less severe ones on the west coast.
  • In 19 severe cyclonic storms, the combined mortality rate exceeded 10,000.
  • In 1999 a super cyclone wreaked havoc in coastal Odisha, claiming more than 30,000 lives. India today is projected to be at ‘very high’ risk levels in terms of intensity of cyclones.
• The mangroves ecosystem along the coastal regions that act as a natural barrier against cyclones and coastal erosion have become severely degraded and face even worse decline due to the cumulative climate change impacts.

Measures taken:

While the upgrade of disaster preparedness mechanisms in many of India’s coastal states has led to a significant reduction in the mortality rate, the number of people affected and the impacts on physical assets have remained unchanged. 

India has been an active and influential global player in the climate change arena from the beginning of the debate. However, domestically, India only started to commission concrete actions on climate change very recently.

• As per the constitutional provisions, flood management is a state subject and as such the primary responsibility for flood management lies with the states.
• The central government has taken various initiatives and set up a number of organizations dealing with the floods.
• The most notable one is the enactment of the National Disaster Management Act, December 2005 and setting up the NDMA, which has been assigned to deal with all types of disasters including the floods. 
• It formed the high-level Prime Minister’s Council on Climate Change in June 2007, which was immediately directed to:
  1. prepare a coordinated response to issues relating to climate change (mitigation and adaptation) at the national level;
  2. provide oversight for the formulation of action plans in the area of assessment, adaptation, and mitigation of climate change; and
  3. periodically monitor key policy decisions.
• An Expert Committee on the Impact of Climate Change has also been set up. It will assess climate change impacts and provide advice on the research activities needed to strengthen efforts to address climate change.
• On June 30, 2008, India launched its National Action Plan on Climate Change (NAPCC), which outlines existing and future policies and programs addressing climate mitigation and adaptation.
  • Emphasizing the overriding priority of maintaining high economic growth rates to raise living standards, the plan “identifies measures that promote our development objectives while also yielding co-benefits for addressing climate change effectively.”
  • The Action  Plan identifies eight core “national missions” running through to 2017: Solar Energy; Enhanced Energy Efficiency; Sustainable Habitat; Water; Sustaining the Himalayan Eco-system; Green India; Sustainable Agriculture; and Strategic Knowledge for Climate Change. Most of these missions have strong adaptation imperatives.
  • The Union Ministry of Environment, Forest and Climate Change on January 18, 2019, notified the 2019 Coastal Regulation Zone (CRZ) norms, replacing the existing CRZ norms of 2011.
    • The new CRZ norms, issued under Section 3 of the Environment Protection Act, 1986, aim to promote sustainable development based on scientific principles taking into account the natural hazards such as increasing sea levels due to global warming.
    • The norms also seek to conserve and protect the environment of coastal stretches and marine areas, besides livelihood security to the fisher communities and other local communities in the coastal area.

Measures need to be taken:

• Preparing for sea-level rise will entail protecting the coast through measures such as natural barriers, levees, flood barriers, and even hard barriers.
• But engineering protection mechanisms are expensive and have consequences for the coastline.
• Stopping infrastructure construction along the coast and integrating anticipated SLR effects into coastal planning is essential.
• The government should not be in a situation of moral hazard where it ends up bailing out investors, insurers and others who have increased their exposure to risk.
• Planning for a retreat from the most vulnerable areas well ahead of time is essential.
• Urban policies, especially in mid-sized towns, should integrate proposals for new migrants.
• Turning border regions into fortress worlds will also not be justified, both in practical and ethical terms.
  • What is required is the preparation in advance with regional policies for labour, regional agreements for migration and for advance skill development.

Conclusion:

• Given that South Asia is one of the most vulnerable regions to climate change and the countries here share ecological zones, borders, and coastlines, in addition to language and family histories, coordinated management of extreme events, advance preparation for migration into mid-size towns and better ecosystem support in the hinterland are useful ways to collaborate and build regional partnerships.
• And, since migrants, in general, cannot, for the most part, be distinguished from climate migrants, rights, services, and policies need to be applied to all migrants. Otherwise, countries will create multiple classes of migrants- as many have accused Australia of doing- based on their reasons for moving and places of origin.
• It is tempting to assume that these are impossible goals to set for India, but that is a short-sighted perspective.
• Our long history has shown that the subcontinent has always been a place that welcomes people.
• Investing in the rural economy, reducing unemployment, reducing poverty and improving measures for sustainability can improve people’s lives and increase their resilience and openness to “others”.
• The protests across the world by people of all ages show that there is fervour for transformation to deal with the climate crisis. This is our historic moment to act decisively.