Coastal Hazard | ENVIRONMENTAL GEOGRAPHY Optional for UPSC

Introduction

Coastlines are highly dynamic natural systems.
It interacts with terrestrial, marine and atmospheric processes and undergo continuous change in response to these processes.
Human society often fails to recognize the hazards related to these dynamics which leads to disastrous consequences.
A coastal hazard may be defined as the occurrence of a phenomenon (e.g. a tropical storm), which has the potential for causing damage to, or loss of, natural ecosystems, buildings, and infrastructure.
These are physical phenomena that expose a coastal area to risk of property damage, loss of life and environmental degradation.

Types of Coastal Hazards

The main coastal hazards are:

1. Cyclones:

Intense tropical storms characterized by low atmospheric pressure, strong winds and heavy rainfall.
Form over warm ocean waters, typically in the tropics or subtropics.
Can cause significant damage to coastal areas through strong winds, storm surges, and inland flooding.
Examples: Hurricane Katrina in 2005 caused widespread destruction along the Gulf Coast of the United States.

2. Storm Surges:

Temporary rise in sea level during a storm, resulting from low atmospheric pressure and strong onshore winds.
Can lead to coastal flooding, erosion, and damage to infrastructure.
Often a major component of the destructive power of hurricanes and tropical storms.
Examples: The 2008 Cyclone Nargis in Myanmar resulted in a storm surge that caused extensive damage.

3. Tsunamis:

Large ocean waves usually caused by undersea earthquakes, volcanic eruptions, or landslides.
Can travel across the ocean and rapidly approach the coast, causing widespread devastation.
Pose a significant threat to coastal communities, resulting in flooding, destruction of structures, and loss of life.
Example: The 2004 Indian Ocean tsunami, triggered by an undersea earthquake.

4. Coastal Flooding:

Inundation of coastal areas due to various factors like heavy rainfall, storm surges, high tides, or sea level rise.
Can result in damage to property, infrastructure, and ecosystems.
Coastal flooding is a common consequence of severe weather events and rising sea levels.
Example: The coastal flooding in the Netherlands during the North Sea flood of 1953.

5. Coastal Landslides:

The movement of coastal land masses, including cliffs or slopes, downward into the sea.
Triggered by factors such as heavy rainfall, erosion, seismic activity, or human activities.
Can cause significant damage to coastal structures, endanger lives, and lead to coastal erosion.
Example: The Oso landslide in Washington, USA, in 2014 resulted in a massive debris flow that had devastating effects.

6. Volcanic Eruptions:

Eruption of volcanoes near coastal areas can lead to various hazards.
Volcanic ash, lava flows, and pyroclastic flows can impact coastal communities.
Coastal areas may also experience tsunamis triggered by volcanic activity.
Example: The eruption of Mount Pinatubo in the Philippines in 1991 produced pyroclastic flows that reached the coastline, causing destruction and altering coastal landscapes.

7. Earthquakes:

Sudden shaking of the Earth's surface caused by the release of energy in the Earth's crust.
Coastal regions near tectonic plate boundaries are susceptible to earthquakes.
Earthquakes can trigger tsunamis, landslides, and coastal subsidence, resulting in widespread damage.
Example: The 2011 Tohoku earthquake in Japan caused a powerful tsunami, leading to widespread devastation and the Fukushima nuclear disaster.

8. Harmful Algal Blooms:

Rapid growth of certain species of algae in coastal waters, often due to excessive nutrient levels.
Some algal species produce toxins harmful to marine life, humans, and animals.
Can lead to fish kills, shellfish contamination, and detrimental impacts on coastal ecosystems and local economies.
Example: The red tide events in Florida, USA, have caused fish kills, respiratory issues in humans.

9. Ocean Acidification:

Increase in the acidity of seawater due to the absorption of carbon dioxide from the atmosphere.
Acidification can harm coral reefs, shell-forming organisms, and other marine life.
Coastal communities relying on these ecosystems may face economic and ecological challenges.
Example: It is leading to coral bleaching and degradation of the reef ecosystem in the Great Barrier Reef in Australia.

10. Saline Intrusion:

The intrusion of saltwater into freshwater aquifers or surface water bodies along the coast.
Can occur due to factors such as sea level rise, groundwater pumping, or drought conditions.
Saline intrusion can contaminate freshwater sources, affecting drinking water supplies and agriculture.
Example: The saline intrusion in Mekong Delta in Vietnam is affecting rice production and freshwater availability.

11. Coastal Erosion:

The gradual or rapid loss of coastal land due to the action of waves, currents, wind, and other processes.
Erosion can result from natural factors or human activities, such as construction and sand mining.
Coastal erosion threatens infrastructure, habitats, and contributes to the loss of valuable land.
Example: The erosion of coastal cliffs along the coastline of England's East Riding of Yorkshire.

12. Sea Level Change:

The long-term alteration in the average level of the ocean's surface caused by factors like thermal expansion and the melting of ice caps and glaciers.
Rising sea levels increase the vulnerability of coastal areas to flooding, erosion, and saltwater intrusion.
Coastal communities worldwide face risks associated with sea level change and must adapt to mitigate impacts.
Example: The Marshall Islands in the Pacific are particularly vulnerable to sea level rise, with communities experiencing increased coastal flooding and the need to relocate due to inundation.

Causes of Coastal Hazards:

1. Natural Factors:

Storms: Severe storms, like hurricanes, can cause coastal flooding and erosion. Example: Hurricane Katrina.
Tsunamis: Underwater earthquakes or landslides can trigger destructive tsunamis. Example: Indian Ocean tsunami.
Sea Level Rise: Global warming leads to rising sea levels, increasing the risk of flooding and erosion. Example: Threat to the Maldives.

2. Human-Induced Factors:

Coastal Development: Poorly planned construction disrupts natural coastal processes, causing erosion. Example: Construction of seawalls.
Deforestation: Clearing coastal vegetation weakens natural barriers against storm surges and erosion. Example: Deforestation of mangroves in Myanmar.
Climate Change: Greenhouse gas emissions intensify storms, exacerbating coastal hazards. Example: Increasing frequency of hurricanes.
Overfishing and Destruction of Marine Habitats: Exploitation and destructive fishing practices harm marine ecosystems, leading to erosion. Example: Coral reef destruction in the Philippines.

Effects

Primary Impact:

Infrastructure damage.
Damage to coastal environment and forests.
Damage to beaches.
Increased erosion.
Increased Mortality.

Socio-economic Impact:

Loss of days for fisherman, school and businessmen.
Slow tourism,
High cost of recovery,
Spread of disease,
Phycological impact

Disaster Management of Coastal Hazards

A. Pre-disaster stage

1. Preparedness (P):

developing emergency response plans, conducting risk assessments, and establishing early warning systems.
Examples: Creating evacuation plans, conducting drills to educate and train the community, stockpiling emergency supplies, and establishing communication protocols.

2. Mitigation (M):

Mitigation focuses on reducing the impact of coastal hazards by implementing measures to minimize vulnerability and exposure. It aims to prevent or reduce the severity of a disaster before it occurs.
Examples: Building seawalls or dikes to protect coastal communities from storm surges, implementing land-use zoning regulations to restrict development in high-risk areas, and restoring and protecting natural coastal buffers like mangroves or dunes.

3. Prevention (P):

Prevention measures aim to avoid or reduce the occurrence of coastal hazards altogether. They focus on addressing the root causes of hazards and eliminating or minimizing the factors that contribute to their occurrence.
Examples: Implementing strict building codes and regulations to ensure structures are designed to withstand potential hazards, enforcing restrictions on activities that could harm the coastline (e.g., sand mining), and promoting sustainable coastal management practices.

B. Disaster stage

1. Rescue operation (R):

This stage involves immediate actions taken to save lives, provide medical assistance, and ensure the safety of affected individuals during and immediately after a disaster.
Examples: Evacuating residents from affected areas, deploying search and rescue teams, providing emergency medical care, and setting up temporary shelters.

C. Post-disaster stage

1. Relief (R):

Relief efforts focus on providing immediate assistance to affected communities to address their urgent needs, such as food, water, shelter, and medical support.
Examples: Distributing relief supplies, setting up temporary camps or shelters, providing emergency healthcare services, and restoring basic infrastructure like electricity and water supply.

2. Recovery (R):

Recovery involves intermediate-term efforts to restore normalcy and rebuild the affected coastal areas.
It aims to repair or reconstruct infrastructure, reestablish essential services, and support the socio-economic recovery.
Examples: Rebuilding damaged structures, repairing coastal roads and utilities, supporting local businesses to resume operations, and providing financial assistance or grants to affected individuals or businesses.

3. Rehabilitation (R):

Rehabilitation focuses on long-term recovery and development, aiming to enhance the resilience of the coastal communities to future hazards.
It involves measures to reduce vulnerability, enhance preparedness, and promote sustainable development.
Examples: Developing comprehensive land-use plans, implementing nature-based solutions like beach nourishment or wetland restoration, conducting public awareness campaigns, and promoting sustainable livelihood options.

Integrated coastal zone management

Integrated coastal zone management means the integration of all aspects of the coastal zone; this includes environmentally, socially, culturally politically and economically to meet a sustainable balance all around
Management practices include:
- Maintaining the functional integrity of the coastal resource systems, without disrupting the environment
- Reducing resource-use conflicts, by making sure resources are used adequately and sustainably,
- Maintaining the health of the environment, which means to protect the ecosystems and natural cycle,
- Facilitating the progress of multisectoral development, which means allowing developers to develop within standards.

NDMA Guideline for Coastal Hazards

Observation Networks, Information Systems, Monitoring, Research, Forecasting & Early Warning
Preparation of detailed maps to delineate coastal wetlands, mangroves and shelterbelts and tracts for coastal bio-shields using best tools, field studies, and satellite data
Hazard Risk Vulnerability and Capacity Assessment
Facilitating last-mile connectivity and access to disaster risk information
Systematic data management of data on disaster damage and loss assessments
Establishing a robust system of locating multi-purpose cyclone shelters and cattle mounds
Ensuring cyclone-resistant design standards are incorporated in the rural/ urban housing schemes in coastal areas
Building all-weather road links to all coastal habitations, between habitations and cyclone shelters/cattle mounds
Maintaining the full designed carrying capacity of main drains and canals
Construction of saline embankments to prevent ingress of saline water associated with cyclonic storm surge
Encouraging public-private partnership with corporate/trusts.
Regulating infrastructure and development activities in coastal zones.
Developing Integrated Coastal Zone Management (ICZM) frameworks
Evolving eco-system restoration plans for degraded ecological zones.
Developing delta water management and freshwater recharge/management options.
Coastal bio-shields spread, preservation and restoration/ regeneration plans.
Implementing coastal flood zoning, flood plain development and flood inundation management and regulatory plans.
Groundwater development and augmentation of freshwater requirement in coastal urban centres.
Development of Aquaculture Parks in the identified potential zones.
Developing integrated hazard mitigation framework taking into account cyclone and associated storm surge, wind hazard, rainfall-runoff, river flood
Geographical Information System (GIS) models for estimating possible areas of inundation along with the depth of inundation (levels), possible damage to infrastructure, crops, houses, etc., evaluating not only the vulnerability but also the changing profile of vulnerability from time to time.