Hazard mapping is the process of establishing geographically where and to what extent particular natural phenomena can cause harm to people, property, infrastructure, and the environment. In India, a country highly vulnerable to diverse natural disasters due to its unique geo-climatic conditions, hazard mapping serves as the foundational pillar for disaster risk reduction (DRR), urban planning, and climate change adaptation.
Types of Hazard Mapping in India
Earthquake Hazard Zonation
The Bureau of Indian Standards (BIS) is the nodal agency for publishing the Seismic Zoning Map of India. The current map divides the country into four seismic zones (Zone II to Zone V), based on the Modified Mercalli (MM) intensity scale and historical seismic data. Zone I is no longer utilized in India.
- Zone V (Very High Damage Risk Zone): Covers the entire northeastern region, parts of Jammu and Kashmir, Ladakh, Himachal Pradesh, Uttarakhand, Rann of Kutch in Gujarat, part of North Bihar, and the Andaman & Nicobar Islands.
- Zone IV (High Damage Risk Zone): Covers remaining parts of Jammu and Kashmir, Ladakh, Himachal Pradesh, Uttarakhand, Sikkim, northern parts of Uttar Pradesh, Bihar, West Bengal, parts of Gujarat, and small portions of Maharashtra and Delhi.
- Zone III (Moderate Damage Risk Zone): Covers Kerala, Goa, Lakshadweep islands, remaining parts of Uttar Pradesh, Gujarat, and West Bengal, parts of Punjab, Rajasthan, Madhya Pradesh, Bihar, Jharkhand, Chhattisgarh, Maharashtra, Odisha, Andhra Pradesh, Tamil Nadu, and Karnataka.
- Zone II (Low Damage Risk Zone): Covers the remaining parts of the country, primarily located within the stable Peninsular shield.
Flood Hazard Mapping
Flood mapping in India is primarily executed by the Central Water Commission (CWC) and the National Remote Sensing Centre (NRSC) using satellite data.
- Chronically Flood-Prone Areas: The Indo-Gangetic-Brahmaputra plains (Assam, Bihar, Uttar Pradesh, and West Bengal) account for the highest flood vulnerability.
- Flash Flood Mapping: Mountainous states like Himachal Pradesh, Uttarakhand, and Jammu & Kashmir are mapped for Cloudburst-induced flash floods and Glacial Lake Outburst Floods (GLOFs).
- Coastal Flooding: Coastal districts of Odisha, Andhra Pradesh, Tamil Nadu, and West Bengal are mapped for storm surge vulnerabilities.
Landslide Hazard Zonation (LHZ)
The Geological Survey of India (GSI) is the national nodal agency for Landslide Susceptibility Mapping. GSI executes the National Landslide Susceptibility Mapping (NLSM) programme.
- Macro Scale Mapping: Done at 1:50,000 scale to identify high-risk zones across 0.42 million square kilometers of landslide-prone areas in India.
- High Vulnerability Zones: The Himalayas (North and Northeast India) due to tectonic activity and steep slopes, and the Western Ghats (South India) due to heavy rainfall and intense weathering.
Cyclone Hazard Mapping
The India Meteorological Department (IMD) and the National Disaster Management Authority (NDMA) map cyclone vulnerabilities along India’s 7,516 km coastline.
- East Coast Vulnerability: Historically higher frequency and intensity; West Bengal, Odisha, Andhra Pradesh, and Tamil Nadu are mapped as highly vulnerable.
- West Coast Vulnerability: Increasing frequency due to Arabian Sea warming; Gujarat and Maharashtra are high-priority mapping zones.
Institutional Framework and Technology Stack
Nodal Agencies for Hazard Mapping
| Hazard Type | Primary Nodal Agency | Key Outputs / Initiatives |
| Earthquakes | Bureau of Indian Standards (BIS) / National Centre for Seismology (NCS) | IS 1893: Criteria for Earthquake Resistant Design of Structures |
| Floods | Central Water Commission (CWC) / NRSC | Flood Forecasting Network, Hydro-meteorological Data |
| Landslides | Geological Survey of India (GSI) | National Landslide Susceptibility Mapping (NLSM) |
| Cyclones | India Meteorological Department (IMD) | Coastal Hazard and Vulnerability Atlas of India |
| Droughts | National Crop Forecasting Centre (NCFC) / Ministry of Agriculture | National Agricultural Drought Assessment and Monitoring System (NADAMS) |
Technological Interventions in Mapping
- Geospatial Technology & Remote Sensing: ISRO’s National Remote Sensing Centre (NRSC) utilizes data from Cartosat, RISAT, and Resourcesat series to generate real-time and historical hazard footprints.
- Bhuvan Portal: ISRO’s geoportal provides visualization services and Earth observation data for disaster management.
- Geographic Information Systems (GIS): Used to overlay hazard layers with socio-economic data (population density, infrastructure) to compute vulnerability and risk.
- LiDAR (Light Detection and Ranging): Employed for high-resolution topographic mapping, essential for landslide tracking and urban flood modeling.
Applications and Regulatory Framework
Disaster Management Act, 2005
The Act mandates the creation of Disaster Management Plans at National, State, and District levels. Hazard maps form the core scientific data required to draft these statutory plans.
National Disaster Management Authority (NDMA) Guidelines
NDMA utilizes hazard maps to formulate National Guidelines for structural and non-structural mitigation strategies, such as the National Cyclone Risk Mitigation Project (NCRMP).
Urban Planning and Building Bylaws
Hazard maps guide the Model Building Bye-Laws (2016) issued by the Town and Country Planning Organisation (TCPO), ensuring that infrastructure in Zone V or floodplains complies with specific safety codes.
Fact-File and Key Trivia for Civil Services Prelims
- Total Vulnerability Profile: About 58.6% of India’s landmass is prone to earthquakes of moderate to very high intensity; over 12% (40 million hectares) is prone to floods; close to 5,700 km of the 7,516 km coastline is prone to cyclones and tsunamis; 68% of the cultivable area is vulnerable to drought.
- The Seismic Gap Concept: Hazard mapping in the Central Himalayas highlights a “seismic gap”—a region that has not experienced a major earthquake in centuries, indicating high accumulated strain.
- South Asian Flash Flood Guidance System (South Asia FFGS): An operational system implemented by the IMD to provide flash flood threats and risks addresses across India, Nepal, Bhutan, Bangladesh, and Sri Lanka.
- Dynamic Landslide Early Warning System (LEWS): GSI, in collaboration with the British Geological Survey, has been testing rainfall-induced landslide alert systems using regional hazard maps.