1.Explain the formation process of tropical cyclones. Discuss its impacts and mention NDMA guidelines.
Tropical Cyclones Tropical cyclones are violent storms that originate over oceans in tropical areas and move over to the coastal areas bringing about large scale destruction caused by violent winds, very heavy rainfall and storm surges. This is one of the most devastating natural calamities. They are known as Cyclones in the Indian Ocean, Hurricanes in the Atlantic, Typhoons in the Western Pacific and South China Sea, and Willy-willies in the Western Australia.
Origin and Formation:
●Tropical cyclones originate and intensify over warm tropical oceans.
●The conditions favourable for the formation and intensification of tropical storms are:
(i) Large sea surface with temperature higher than 27° C;
(ii) Presence of the Coriolis force;
(iii) Small variations in the vertical wind speed;
(iv) A pre-existing weak low-pressure area or low-level-cyclonic circulation;
(v) Upper divergence above the sea level system.
●The energy that intensifies the storm, comes from the condensation process in the towering cumulonimbus clouds, surrounding the centre of the storm.
●With continuous supply of moisture from the sea, the storm is further strengthened. On reaching the land the moisture supply is cut off and the storm dissipates.
●The place where a tropical cyclone crosses the coast is called the landfall of the cyclone.
●The cyclones, which generally cross 20 N latitude, recurve and they are more destructive. A mature tropical cyclone is characterised by the strong spirally circulating wind around the centre, called the eye.
●The diameter of the circulating system can vary between 150 and 250 km. The eye is a region of calm with subsiding air.
●Around the eye is the eye wall, where there is a strong spiralling ascent of air to greater height reaching the tropopause. The wind reaches maximum velocity in this region, reaching as high as 250 km per hour.
●Torrential rain occurs here. From the eye wall rain bands may radiate and trains of cumulus and cumulonimbus clouds may drift into the outer region.
●The diameter of the storm over the Bay of Bengal, Arabian sea and Indian ocean is between 600 – 1200 km. The system moves slowly about 300 – 500 km per day. The cyclone creates storm surges and they inundate the coastal lowlands. The storm peters out on the land.
Consequences of Tropical cyclones:
- Heavy Rainfall and Flooding: Cyclone Fani, which struck the Indian state of Odisha in May 2019, exemplifies the impact of heavy rainfall and flooding. The cyclone brought intense rainfall, leading to severe flooding in several districts. Rivers overflowed, inundating large areas, and damaging homes, infrastructure, and crops. The floodwaters disrupted normal life and created a significant humanitarian crisis in the affected regions.
- Strong Winds: Cyclone Amphan, which hit India and Bangladesh in May 2020, caused widespread destruction due to its strong winds. With wind speeds reaching up to 155 km/h (96 mph), the cyclone uprooted trees, damaged buildings, and disrupted power and communication lines. The intense winds were devastating in West Bengal and the Sundarbans region, leading to extensive damage and disruption.
- Storm Surge: Cyclone Michaung in 2023 and Fengal in 2024, recently highlighted the vulnerability of Tamil Nadu and Andhra Pradesh to tropical cyclones, with significant implications for these coastal regions. A report by Climate Trends reveals that about 2.9 million people in Andhra Pradesh are highly vulnerable to such storms, intensified by the fact that 3.3 million people reside within 5 kilometers of the coastline. This proximity to the coast substantially raises the risk of exposure to cyclones and their devastating effects, including storm surges, flooding, and strong winds.
- Landslides: Cyclone Yash, which struck eastern India in May 2021, triggered heavy rainfall that caused landslides in the hilly areas of West Bengal and parts of Jharkhand. The landslides resulted in road blockages, damage to infrastructure, and increased challenges for rescue and recovery operations. The heavy rains and unstable terrain exacerbated the impact on these regions.
- Economic and Social Impact: Cyclone Ockhi, which affected Tamil Nadu and Kerala in December 2017, had significant economic and social repercussions. The cyclone caused extensive damage to homes, infrastructure, and agricultural lands. The displacement of communities and the destruction of property led to a severe humanitarian crisis, with prolonged recovery efforts needed to rebuild affected areas and restore normalcy.
- Environmental Impact: Cyclone Vardah, which struck Chennai and Tamil Nadu in December 2016, had notable ecological impacts. The cyclone caused significant damage to coastal and urban green spaces, including destroying trees and vegetation. The flooding and storm surge associated with the cyclone also led to pollution of water sources, affecting local ecosystems and wildlife.
NDMA Guidelines for Cyclones:
The National Disaster Management Authority (NDMA) of India provides comprehensive guidelines for managing disasters, including cyclones. These guidelines are designed to mitigate the impact of cyclones and enhance preparedness, response, and recovery efforts.
- Cyclone Preparedness and Mitigation
a. Early Warning Systems: Establish and maintain robust early warning systems to provide timely and accurate information about cyclone formation and movement.
b. Public Awareness and Education: Conduct public awareness campaigns and educational programs to inform communities about cyclone risks and safety measures.
c. Infrastructure Resilience: Improve the resilience of infrastructure to withstand cyclone impacts, including strengthening buildings, roads, and coastal defenses.
d. Community-Based Preparedness: Develop and implement community-based preparedness plans, including evacuation plans and shelter arrangements. - Cyclone Response and Management
a. Emergency Operations Centers (EOCs): Activate EOCs at the state and district levels to coordinate response efforts during a cyclone.
b. Evacuation and Shelter Management: Implement evacuation plans to safely move people from vulnerable areas to designated shelters.
c. Search and Rescue Operations: Conduct search and rescue operations to assist affected individuals and communities.
d. Relief and Rehabilitation: Provide immediate relief supplies, including food, water, medical aid, and other essentials to affected populations. - Post-Cyclone Recovery and Reconstruction
a. Damage Assessment: Conduct thorough damage assessments to evaluate the impact of the cyclone on infrastructure, properties, and livelihoods.
b. Reconstruction and Rehabilitation: Develop and implement reconstruction plans to rebuild affected areas, focusing on resilience and sustainable development.
c. Financial Support and Insurance: Facilitate financial support and insurance mechanisms for individuals and businesses affected by the cyclone.
d. Review and Improvement: Review and analyze the response and recovery efforts to identify lessons learned and areas for improvement. - Coordination and Collaboration
a. Multi-Agency Coordination: Ensure coordination among various government agencies, NGOs, and community organizations involved in disaster management.
b. International Cooperation: Engage in international cooperation and exchange of best practices for cyclone management.