Floods in India, Causes, Impacts, Mitigation, Measures

Floods are the most common form of natural disaster, occurring when a large amount of water submerges normally dry ground. Floods are frequently produced by excessive rainfall, quick snowmelt, or storm surge from a tropical cyclone or tsunami in coastal locations. India is highly vulnerable to floods in which Assam, Bihar, Odisha, Uttar Pradesh, and West Bengal are largely affected. Flood disasters affect people and the impact of floods cannot be completely prevented, while measures can be taken to mitigate the impact and ensure that people are prepared to deal with the consequences of the flood hazards.

Flood-prone Areas of India

India is the worst-affected country by floods after Bangladesh, accounting for one-fifth of all flood-related deaths worldwide. According to the Ministry of Jal Shakti, the recent estimate on flood-prone areas in the country is 49.15 Mha. The annual average cropped area affected by flood is approximately 3.7 million hectares.

• Indo-Gangetic- Brahmaputra plains: The most flood-prone areas in India are the Brahmaputra and the Ganga River basins in the Indo-Gangetic- Brahmaputra plains in North and Northeast India, which carry 60 percent of the nation's total river flow.
• Affected states: Nearly 75% of total Indian rainfall occurs during a brief monsoon season (June-September). As a result, the rivers witness a heavy discharge during these months, leading to widespread floods in Uttar Pradesh, Bihar, West Bengal, and Assam.
  • Assam Valley is highly flood-prone, primarily due to heavy rains and silting of tributaries like Dihang and Lohit.
  • In Kashmir Valley, the Jhelum is unable to carry the river discharge. 
  • In Punjab and Haryana, the problem is primarily due to inadequate drainage. 
  • The Central Indian and peninsular river basins, covering Madhya Pradesh, Orissa, Andhra Pradesh, Maharashtra, and Gujarat, contain the Tapi, Narmada, and Chambal rivers, which often experience excess rainfall.
  • In Andhra Pradesh, the Kolleru lake submerges vast areas along its fringes and cyclonic storms bring heavy flooding in the coastal areas. 
• Flash flood-prone areas: In recent decades, states such as Rajasthan, Gujarat, Haryana, and Punjab have been inundated by flash floods.

Causes of Floods in India

India is prone to floods due to its geography, heavy rainfall during the monsoon and global warming leading to more frequent and intense rainfall events, etc. Floods are caused by both natural as well and anthropogenic factors.

Natural Causes

• Heavy rainfall: Heavy rain in the catchment area of a river causes water to overflow its banks, which results in the flooding of nearby areas. 
  • During the monsoon season, there are many events of flood in northern and northeastern India and the Gangetic plains due to heavy rainfalls.
• Cloud Burst: Cloud Burst causes intense precipitation in a very short duration which can cause a flood. 
  • These natural incidents are observed in the Himalayan regions. 
• Sediment deposition: Large silts and sediments get deposited in the river bed, which reduces the carrying capacity of rivers. 
• River channel changes: Natural processes such as erosion and meandering can alter river channels over time. These changes can affect the capacity of rivers to carry water, leading to increased flood risk. 
  • River Kosi in Bihar is known as the “sorrow of Bihar” due to frequent floods caused by its nature of changing course. 
• Cyclones: India's coastal regions, especially along the Bay of Bengal and Arabian Sea, are susceptible to tropical cyclones, which can cause significant flooding due to heavy rainfall and storm surges. 
  • In December 2023, Cyclone Michaung made landfall in Andhra Pradesh resulting in storm-induced floods, leading to casualties and damage to properties.
• Himalayan glacier melt: The melting ice can result in the formation of glacial lakes, which pose a risk of glacial lake outburst floods (GLOFs). Example: Uttarakhand Glacial burst.
• Climate Change:Climate change has aggravated the situation of flood risks. 
  • In mountainous regions, three effects of climate change are there -more intense precipitation due to a warmer atmosphere, shifting snow and rain patterns, and the effects of wildfires on the landscape.
  • Climate change is also causing intense rain and the occurrence of tropical rainfall in the Indian Ocean region. Thus, it has also caused an increased risk of floods in the Western Ghat region.

Anthropogenic Causes

• Deforestation: Vegetation plays a crucial role in absorbing rainwater and reducing surface runoff. Deforestation disrupts natural rainwater absorption and reduces surface runoff, increasing runoff volumes and river flooding risk.
  • According to a study, with every 10 percent increase in trees being cut down, the flood risk increases by up to 28 percent. 
• Poor drainage: Urban growth converts natural land into impermeable surfaces. This reduces land's ability to absorb water and leads to increasing surface runoff, and insufficient or poorly maintained drainage systems increase flood risk.
  • For instance, recent floods in Bangalore are more attributed to the reasons for poor drainage and urbanisation.
• Dam and embankment failure: Dam collapse and river embankment failures due to poor infrastructure can also cause floods. 
  • In case of heavy rainfall and limitation of water storage capacity of dams, the dam gates are opened which causes severe floods in the nearby areas. 
• Encroachment on floodplains: Construction and settlement in floodplain areas disrupt the natural flow of water during floods. 
  • Encroachment reduces the capacity of floodplains to store excess water, causing it to overflow into surrounding areas.
• Encroachment of water bodies: Encroachment of lakes, ponds and other water bodies aggravates the risk of floods because they cannot contain the extra water when the situation of flooding arrives. 

Impacts of Floods in India

Floods are generally destructive to humans and the natural environment, but they also contribute positively in some cases.

Negative Impact

• Immediate impacts: It causes loss of life and property, crop destruction, livestock loss, infrastructure malfunction, disruption in movement and deterioration of health conditions due to waterborne diseases.
  • According to Central Water Commission (CWC) data, in the last 65 years, floods killed 109,412 people, and 258 million hectares of crops were damaged.
• Economic loss: Floods cause damage to infrastructure, leading to livelihood loss and disruption in industries and businesses, causing production delays, supply chain disruptions, and financial losses. 
  • According to SBI research, floods in North India caused an estimated economic loss worth ₹10000-15000 crore in 2023.
• Displacement: Floods result in a humanitarian crisis and displacement of the people. 
  • Flooding in Jammu and Kashmir in 2015, Uttarakhand in 2013, and Assam in 2012 displaced millions of people.
• Health risks and waterborne diseases: Floods contaminate water sources, leading to an increased risk of waterborne diseases such as cholera, typhoid, and diarrhoea. 
  • The World Health Organization estimates that floods in India result in the loss of millions of productive days and contribute to a substantial disease burden.
• Environmental impacts: Floods cause soil erosion, sedimentation, and degradation of ecosystems. 
  • Sediment-laden floodwaters can damage agricultural land, affect soil fertility, and impact biodiversity.

Positive Impact

• Recharging water sources: Inundation of the flood plains helps recharge the groundwater, which is an important source of drinking water and is essential for agriculture.
• Agriculture: Floodwaters carry nutrients and sediments, which are deposited on flood plains, enriching the soil. Rice paddies are flooded deliberately to take advantage of this natural fertilisation process.
• Rejuvenation of the river ecosystem: The river ecosystem is crucial for the biodiversity of fish, wildlife, and waterfowl, and its seasonal variability and varied sediment and flow regimes help maintain this balance.
• Fishery: Floods trigger aquatic species spawning and migration, providing abundant fish supply and alternative income sources at the household level.

India’s Preparedness for Floods

The Indian government has implemented many initiatives and policies to lessen the impact of floods through various state and central disaster management support organisations. 

• Central Water Commission (CWC): It was set up in 1945 and focuses on flood control, water resource conservation, irrigation, hydropower generation, flood management, and river conservation in the country..
• National Disaster Management Authority (NDMA):  NDMA has prepared these Guidelines for Flood Management, to assist the ministries and departments of the GOI, the state governments, and other agencies in preparing Flood Management plans (FMPs).
• The National Water Policy (2012): It emphasises flood control through structural measures, integrated reservoir operation, natural drainage system rehabilitation, farming systems, and non-agricultural development, aiming for long-term solutions to devastating floods.
• Flood Forecasting Network: The CWC has implemented a flood forecasting system with 175 stations across major interstate rivers, enabling real-time data collection, automatic transmission, flood forecast formulation, and efficient information dissemination.
• Flood Management and Border Areas Programme (FMBAP): It is being implemented throughout the country for effective flood management, erosion control, and anti-sea erosion and to help maintain peace along the border.
• Structural Measures: Since 1954, the government has constructed 33,928 km of new embankments and 38,809 km of drainage channels, completed 2,450 town protection works, and raised 4,721 villages above flood levels.
• Post-disaster response and recovery: India has set mechanisms for the post-disaster response, such as search and rescue operations, relief and rehabilitation camps, NDRF forces, and the use of earth observation satellites.
• Cooperation with the neighbouring countries: India has cooperation with neighbours like Nepal, China, and Bhutan for the exchange of hydro-meteorological data for early preparedness of flood management.

Challenges with Flood Management in India

Despite significant investments and ongoing flood management measures in India, socioeconomic damages and mortality tolls remain high. The following are the challenges of flood management in India: 

• Complex hilly regions: Flood risk management in hilly regions is still in the infancy stage, particularly due to complex and tough terrain with limited accessibility and a low level of monitoring.
• Technological problems: Innovative technologies are emerging to help manage flood risk, but these are not always straightforward to implement and technology alone will not address all our challenges.
• Lack of policy implementation: Though non-structural measures (such as regulations, land use planning, flood zoning, and flood forecasting) find their mentions in flood-related policies and are practised in a few regions of the country, they are yet to be enacted extensively by the States.
• Addition of new flood-prone areas: Flood-prone regions are growing rapidly due to climate and human factors, posing challenges for organizations to implement effective plans and policies to minimize human and economic losses during and after disasters.
• Policy failure: Over the years, the National Flood Commission recommendations have failed to achieve much success in mitigating floods, and the data show that flood damage and fatalities have only increased for years.

Suggested Measures

A NITI Aayog report on flood management under Rajiv Kumar has suggested effective and long-lasting strategies for flood control and management that involve structural and non-structural measures along with the use of modern technologies.

• Non-structural measures:
  • Implementation of floodplain zoning: It has been suggested to implement the floodplain zoning approach as mandated by the Ministry of Jal Shakti.
  • Scientific research: It has called formodernisation in the collection of hydrometeorological data, flood forecast formulation, forecast dissemination and focus on scientific research in the development of a Model-based system to forecast flash floods.
  • Use of space technology: Emphasis is to be laid on the application of space technology and the use of state-of-the-art technology in spatial flood early warning and near real-time monitoring and mapping of floods.
• Structural measures: 
  • Storage reservoirs: The construction of large storage reservoirs that moderate flood peaks is the need of the hour. 
  • Embankments: The raising and strengthening of existing embankments and creating new embankments, channelisation, drainage & channel improvement, and anti-erosion works have been suggested. 
  • Interlinking of rivers: The projects for interlinking of rivers for diversion of flood water to water-scarce regions should be completed. 
  • Emergency Action Plans for all big dams should be prepared and implemented when needed.

Floods in India FAQs

Q1. What are the causes of floods?

Ans. Flooding is a result of heavy rain, snow and ice melting, and can be exacerbated by geography, particularly in areas near rivers and cities.

Q2. What are the impacts of flood?

Ans. Floods pose a significant threat to life, property, infrastructure, and public services, causing costly, disruptive, and traumatic long-term consequences for affected communities.

Q3. How are floods predicted?

Ans. Flood predictions rely on real-time data on rainfall, river stage changes, and river drainage basin characteristics like soil-moisture, ground temperature, snowpack, and topography to predict the extent and severity of a flood.

Q4. Which are the most flood-prone areas of India?

Ans. The most flood-prone areas in India are the Brahmaputra and Ganga River basins in the Indo-Gangetic- Brahmaputra plains in North and Northeast India, which carry 60 per cent of the nation's total river flow.

Q5. Why India is more prone to floods?

Ans. India is prone to floods due to its monsoon climate and the extensive network of rivers that run through the country and also affected by cyclones due to the presence of a longer coastline.