Floods

GS3 – Disaster Management

A flood is the overflow of water onto normally dry land, typically due to excessive rainfall, river overflow, dam breakage, or storm surges. Floods are among the most frequent and damaging natural disasters.

Types of Floods

Type	Description
Riverine Floods	Caused by the overflow of rivers during intense rainfall or snowmelt (e.g., Brahmaputra floods).
Urban Floods	Occur in cities due to inadequate drainage systems during heavy rains (e.g., Mumbai floods).
Flash Floods	Sudden and intense flooding caused by short bursts of rainfall, often in hilly areas.
Coastal Floods	Result from storm surges during cyclones or tsunamis (e.g., Odisha, Tamil Nadu).
Pluvial Floods	Flooding due to excessive rainfall not absorbed by the ground, even without nearby water bodies.
Glacial Lake Outburst Floods (GLOFs)	Caused by the sudden release of water from a glacial lake (e.g., Chamoli, Uttarakhand).

 

Major Causes of Floods in India

 Natural Causes

• Heavy Monsoon Rainfall
• Snowmelt in Himalayan Rivers
• Cyclones & Storm Surges
• Topography & River Siltation
• Climate Change & Extreme Weather Events

 Anthropogenic Causes

• Encroachment of floodplains
• Deforestation & soil erosion
• Unplanned urbanization
• Poor drainage systems
• Dam mismanagement (sudden water release)

 Flood-Prone Regions in India

Region	Rivers Involved / Cause
Assam & NE States	Brahmaputra, Barak
Bihar & UP	Ganga, Kosi, Ghaghara
West Bengal	Damodar, Ganga
Odisha & AP	Cyclonic storms & river overflows
Kerala & Karnataka (Western Ghats)	Heavy rainfall, flash floods
Urban areas	Mumbai, Delhi, Chennai, Bengaluru

 

 Impacts of Floods

 Social:

• Loss of life & displacement
• Water-borne diseases
• Destruction of homes, schools, hospitals

 Economic:

• Damage to crops, infrastructure, transport
• Disruption of livelihoods
• Financial burden on relief & rehabilitation

 Environmental:

• Erosion & land degradation
• Siltation of rivers
• Destruction of ecosystems and habitats

 Flood Management in India

 Structural Measures

• Dams, reservoirs & embankments
• Drainage channels
• Flood zoning and watershed management
• Urban stormwater drains

 Non-Structural Measures

• Flood forecasting & early warning systems (e.g., IMD, CWC)
• Disaster response & evacuation plans
• Awareness campaigns and mock drills
• Remote sensing and GIS for flood mapping
• National Disaster Management Authority (NDMA) Guidelines

 Institutional Mechanisms

Institution/Plan	Role
NDMA (2005)	Lays out guidelines on flood preparedness & mitigation
CWC (Central Water Commission)	Monitors rivers and provides flood forecasts
State Disaster Management Authorities (SDMAs)	Local flood response
IMD & ISRO	Weather forecasts & satellite-based flood mapping
NCRMP	National Cyclone Risk Mitigation Project (for coastal flooding)

 

 Recent Initiatives & Best Practices

• Flood Early Warning System (FEWS) – Used in Mumbai, Chennai, Guwahati
• Mukhya Mantri Jal Swavlamban Abhiyan (Rajasthan) – Watershed management
• National Hydrology Project – Real-time data for flood risk mapping
• Room for the River Project (Netherlands) – International best practice for floodplain restoration