Cyclones: A Natural Hazard

Let’s start from the definition —

A Cyclone is a large-scale low-pressure system surrounded by high-pressure zones, causing swirling winds around the center.

In simple words —
👉 Air rushes inward towards a low-pressure center.
👉 Because of Coriolis Force, it starts rotating:

• Anti-clockwise in the Northern Hemisphere
• Clockwise in the Southern Hemisphere

At the center lies the eye of the cyclone — calm, clear, and almost windless.
But just 20–30 km away, wind speeds can exceed 150 km/h and bring torrential rains.

⚙️ Formation of a Tropical Cyclone (Tropical Cyclogenesis)

You can read in detail about Tropical Cyclones in Climatology section.
👉 Characteristics of Tropical Cyclones
👉 Types of Tropical Cyclones
👉 Origin of Tropical Cyclones
👉 Convective Cyclogenesis

🇮🇳 Cyclone Risks in India

India’s 8000 km coastline faces cyclones from both Bay of Bengal (east) and Arabian Sea (west).

⚡ Cyclone Pattern

• Bay of Bengal: 58% of cyclones → more intense and frequent.
• Arabian Sea: 25% → relatively weaker but increasing recently.
• Season:
  • Pre-Monsoon (Apr–May) and Post-Monsoon (Oct–Nov) are peak periods.
  • Post-monsoon cyclones are usually stronger.

🗺️ Vulnerable States and UTs

13 coastal states/UTs with 84 coastal districts are affected:

• Category I (High Vulnerability): Andhra Pradesh, Odisha, West Bengal, Tamil Nadu, Gujarat.
• Category II (Moderate): Maharashtra, Karnataka, Kerala, Goa, Puducherry, Lakshadweep, Daman & Diu, Andaman & Nicobar Islands.

🌀 NDMA Guidelines (2008) – Management of Cyclones

NDMA’s principle: Cyclone mitigation must be multi-sectoral, combining early warning, infrastructure safety, community preparedness, and ecosystem-based protection.

Let’s understand the framework 👇

1️⃣ Early Warning System

• IMD operates the Cyclone Warning Dissemination System (CWDS) —
  a satellite-based system that directly communicates cyclone alerts to coastal areas.
• Area Cyclone Warning Centres (ACWCs): Kolkata, Chennai, Mumbai.
• Cyclone Warning Centres (CWCs): Bhubaneswar, Visakhapatnam, Ahmedabad.
• Doppler Weather Radars monitor real-time wind speed and direction.

🛫 Aircraft Probing of Cyclones (APC)

• Aircraft surveillance studies the cyclone core and cloud-aerosol interactions to improve forecasting accuracy.

2️⃣ Communication Infrastructure

• Establishment of National Disaster Communication Infrastructure (NDCI) across NDMA, MHA, and coastal SDMAs for seamless data exchange during disasters.

3️⃣ Structural and Coastal Safety

• Ensure cyclone-resistant construction of lifeline buildings (hospitals, schools).
• Build multi-purpose cyclone shelters and raised cattle mounds.
• Develop all-weather evacuation roads connecting habitations to shelters.
• Construct saline embankments and coastal bio-shields (mangroves) to reduce storm surge impact.
• Maintain capacity of drains and canals for water discharge.

IMD’s Four-Colour Warning Codes

Code	Meaning	Action
🟢 Green	“All is well”	No warning issued
🟡 Yellow	“Be aware”	Weather likely to worsen
🟠 Orange	“Be prepared”	Bad weather imminent – disruption likely
🔴 Red	“Take action”	Severe storm guaranteed – full response needed

National Cyclone Risk Mitigation Project (NCRMP)

A flagship initiative to reduce coastal vulnerability —
jointly implemented by NDMA, MHA, and State Governments, partially funded by World Bank.

🎯 Objectives

• Improve early warning and communication.
• Strengthen community-level capacity and evacuation systems.
• Provide emergency shelters and protective infrastructure.
• Mainstream disaster risk reduction into coastal development planning.

🧭 Implementation

• NDMA (National Level) → coordination and funding.
• NIDM → capacity building and training.
• States → execution via State Disaster Management Authorities (SDMAs).

⚠️ Challenges in Cyclone Risk Management

1️⃣ Weak Local Preparedness

• Often, warnings are not acted upon due to poor coordination and lack of awareness.

2️⃣ Limited Community Participation

• Disaster management is still largely top-down — insufficient grassroots involvement.

3️⃣ Technological Gaps

• Absence of a fully automated national control center at NDMA/MHA for real-time operations.

4️⃣ Network Integration

• Various agencies (IMD, INCOIS, ISRO, NDMA) operate isolated systems —
  integration and interoperability remain weak.

5️⃣ Need for Comprehensive CDMIS

• A Cyclone Disaster Management Information System (CDMIS) is needed to link early warning, response, and recovery under one digital platform.

🌿 Ecosystem-Based Protection

Don’t forget — nature is the best engineer.
Coastal ecosystems like mangroves, sand dunes, and coral reefs absorb wave energy and act as natural barriers.
Loss of these increases coastal vulnerability — hence, coastal afforestation and bio-shields are a key NDMA strategy.