Bihar floods

Bihar floods
Name	Bihar floods
Native name	बाढ़/ବାଢ଼
Settlement type	Natural disaster
Coordinates	25.0961° N, 85.3131° E
Subdivision type	Country
Subdivision name	India
Subdivision type1	State
Subdivision name1	Bihar
Area total km2	94163
Population total	104099452
Population as of	2011 census

Bihar floods are recurrent seasonal inundations affecting the Indian state of Bihar primarily during the South Asian monsoon, driven by heavy rainfall, Himalayan snowmelt, and river dynamics. These events repeatedly impact the Ganges River basin, the Kosi River, the Gandak River, and the Karnali River catchments, causing widespread displacement, agricultural loss, and infrastructure damage across districts such as Darbhanga district, Supaul district, and Motihari. Responses involve state agencies like the Government of Bihar, federal entities including the National Disaster Management Authority, and international organizations such as the United Nations and International Red Cross and Red Crescent Movement.

Geography and Hydrology

Bihar lies largely within the Gangetic Plain, bounded by the Himalayas to the north and the Chota Nagpur Plateau to the south, drained by major rivers including the Ganges River, Ghaghara River, Gandak River, and Kosi River. The Siwalik Hills and transboundary catchments in Nepal influence discharge regimes into Bihar through tributaries like the Bagmati River and Kamla River. Alluvial soils, active fluvial channels, and extensive floodplains near cities such as Patna and Munger create natural storage and conveyance zones; embanked systems like the Eastern India floodplain canals interact with oxbow lakes and alluvial fans to modulate inundation patterns.

Causes and Contributing Factors

Monsoon variability driven by the Southwest Monsoon and teleconnections such as the El Niño–Southern Oscillation and Indian Ocean Dipole modulate rainfall intensity across the Indo-Gangetic Plain. Transboundary snowmelt from the Himalaya and episodic extreme precipitation events in Nepal raise fluvial stages in tributaries including the Kosi River and Gandak River. Anthropogenic influences—river channelization projects, embankment construction associated with Farakka Barrage, deforestation in upstream basins of Uttarakhand and Nepal, and sedimentation from soil erosion in catchments—alter hydraulic residence times and channel capacity. Urban expansion of Patna and land-use change in districts such as Muzaffarpur reduce infiltration and elevate runoff.

Historical Flood Events and Impact

Major historical events trace back to colonial-era inundations documented during the British Raj and catastrophic episodes such as the 2008 Kosi breach that displaced hundreds of thousands and re-routed the Kosi River across Supaul district and Darbhanga district. Other significant years include the 1978, 1998, 2004, 2015, and 2017 floods, with widespread impacts in districts like Katihar district and East Champaran. Impacts encompass loss of life, destruction of cultural heritage sites in Patna Sahib and Vaishali, crop failure on paddy fields, damage to transport corridors including the Howrah–Delhi main line and national highways, and disruption to health services at facilities such as the All India Institute of Medical Sciences, Patna.

Humanitarian Response and Relief Efforts

Relief operations mobilize state disaster response forces, the National Disaster Response Force, and district administrations coordinating with the Indian Armed Forces for search-and-rescue and aerial relief. International humanitarian assistance has involved agencies like the United Nations Office for the Coordination of Humanitarian Affairs and the International Federation of Red Cross and Red Crescent Societies. Non-governmental organizations such as Practical Action and CARE India provide shelter, water, sanitation, and livelihood support; faith-based organizations and civil society groups from Gaya and Madhubani contribute local relief. Emergency measures include temporary camps, mobile medical units, and distribution of foodgrain from the Food Corporation of India.

Government Policy, Mitigation, and Infrastructure

Policy responses include integrated basin management initiatives coordinated through the Ministry of Jal Shakti and bilateral flood management dialogues with Nepal under treaties and commissions like the India–Nepal Treaty of Trade frameworks and hydrological cooperation platforms. Structural measures involve embankments, spurs, sluice gates, and reservoirs such as those on tributaries coordinated with agencies like the Central Water Commission. Non-structural strategies include resettlement policy instruments, floodplain zoning in state planning under the Bihar State Disaster Management Authority, and investment in rural roads under programs like the Pradhan Mantri Gram Sadak Yojana to improve post-flood access.

Environmental and Socioeconomic Consequences

Floods reshape fluvial geomorphology, accelerate sediment deposition, and affect wetlands like the Kanwar Lake, altering biodiversity linked to species recorded in Bihar Museum inventories. Recurrent inundation undermines agrarian livelihoods centered on rice, pulses, and jute cultivation in districts such as Begusarai and Saran district, heightens food insecurity managed by entitlements under the Public Distribution System (India), and exacerbates public health risks including waterborne diseases treated at facilities like Sadar Hospital. Socioeconomic fallout includes migration to urban centers such as Patna and Bengaluru for work, strain on educational institutions like Patna University, and long-term infrastructure rehabilitation financed through state budgets and national schemes like the National Rural Livelihood Mission.

Flood Forecasting, Early Warning, and Preparedness

Forecasting employs hydrometeorological models run by the India Meteorological Department in conjunction with real-time gauging by the Central Water Commission and telemetry networks across transboundary transits in Nepal. Early warning dissemination uses district emergency operations centers, community alert systems in villages of Darbhanga district, and mass media including All India Radio and regional television channels. Preparedness actions emphasize community-based disaster risk reduction pioneered by NGOs linked to the National Institute of Disaster Management and capacity building through training programs for local volunteers and panchayats under schemes administered by the Ministry of Home Affairs (India).

Category:Natural disasters in Bihar Category:Floods in India