Urban Floods in India

Syllabus: GS1/ Geographical Features & their Location, Changes in Geographical Features, Floods

In Context

• Cyclone Michaung recently made landfall in Andhra Pradesh causing floods in Chennai. 

Urban Floods

• About: 
  • Increased incidence of high-intensity rainfall in short duration is mainly responsible for urban floods.
  • It is further compounded by unplanned growth, encroachment of natural water bodies, poor drainage system, etc. 
  • Urban flooding is significantly different from rural flooding as urbanization leads to developed catchments, which increases the flood peaks from 1.8 to 8 times and flood volumes by up to 6 times.
    • Consequently, flooding occurs very quickly due to faster flow times.
• Causes:
  • Weather systems: A special feature in India is that we have heavy rainfall during monsoons.
    • There are other weather systems also that bring in a lot of rain. 
    • Storm surges can also affect coastal cities/ towns. 
  • Dam water: Sudden release or failure to release water from dams can also have a severe impact. 
  • Urban heat island: The urban heat island effect has increased rainfall over urban areas. 
  • Climate Change & sea level rise: Global climate change is resulting in changed weather patterns and increased episodes of high-intensity rainfall events occurring in shorter periods.
    • Then the threat of sea-level rise is also looming large, threatening all the coastal cities. 
    • Cities/towns located on the coast, on river banks, upstream/ downstream of dams, inland cities and in hilly areas can all be affected.
• Consequences:
  • Urban areas are densely populated and people living in vulnerable areas suffer due to flooding, sometimes resulting in loss of life. 
  • It is not only the event of flooding but the secondary effect of exposure to infection also has its toll in terms of human suffering, loss of livelihood and, in extreme cases, loss of life.

Urban Challenges & Floods in India

• There has been an increasing trend of urban flood disasters in India over the past several years whereby major cities in India have been severely affected.
• Poor maintenance: These capacities have been getting very easily overwhelmed whenever rainfall of higher intensity has been experienced.
  • The systems very often do not work to the designed capacities because of very poor maintenance. 
• Encroachment & Habitations: Encroachment is a major problem in many cities and towns.
  • Natural streams and watercourses have formed over thousands of years due to the forces of flowing water in the respective watersheds. 
  • Habitations started growing into towns and cities alongside rivers and watercourses. 
  • As a result of this, the flow of water has increased in proportion to the urbanization of the watersheds. 
• Loss of drains: Ideally, the natural drains should have been widened (similar to road widening for increased traffic) to accommodate the higher flows of stormwater.
  • But on the contrary, there have been large-scale encroachments on the natural drains and the river floodplains. 
  • Consequently, the capacity of the natural drains has decreased, resulting in flooding. 
• Improper disposal systems: Improper disposal of solid waste, including domestic, commercial and industrial waste and dumping of construction debris into the drains also contribute significantly to reducing their capacities.
  • It is imperative to take better operations and maintenance actions.
• Insufficient policy attention: Even though urban flooding has been experienced over decades in India, sufficient attention was not given to planning specific efforts to deal with it.

Government Initiatives

• Role of States & ULBs: Management of urban flooding falls under the purview of the State Governments and the Urban Local Bodies / Urban Development Authorities who are responsible for maintaining the drainage and sewerage system.
  • Several initiatives have been taken by the Union Government to encourage groundwater recharge and other nature-based solutions to tackle urban flooding in flood-prone areas. 
• NDMA Guidelines: As a part of its mandate, the National Disaster Management Authority (NDMA) has made efforts to prepare the National Guidelines on Management of Urban Flooding.
• Master Plan for Artificial Recharge to Groundwater – 2020: The plan has been prepared by the Central Ground Water Board (CGWB) in collaboration with States/UTs envisaging the construction of about 1.42 crore rainwater harvesting and artificial recharge structures in the country to harness 185 Billion Cubic Meter (BCM) of water.
• Jal Shakti Abhiyan (JSA): GOI is implementing Jal Shakti Abhiyan (JSA) in the country in which special emphasis is being given for rainwater harvesting/groundwater recharge. 
• Amrit Sarovar Mission: The mission has been launched to develop and rejuvenate 75 water bodies in each district of the country to celebrate Azadi ka Amrit Mahotsav for rainwater harvesting/recharge.
• AMRUT: Under the Atal Mission for Rejuvenation and Urban Transformation (AMRUT) 2.0 Scheme, provisions have been made for harvesting the rainwater through stormwater drains into a water body (which is not receiving sewage/effluent) & creation/ strengthening of stormwater drains around water body.
• The National Water Policy (2012): The policy is formulated by this Ministry inter alia advocates that the conservation of rivers, river corridors, water bodies and infrastructure should be undertaken in a scientifically planned manner through community participation.
• Urban Flood Mitigation Project: India’s maiden urban flood mitigation project worth Rs 561 crore under the National Disaster Mitigation Fund (NDMF). 

Suggestions & way ahead

• For Chennai: 
  • The suffering caused by the latest floods should push the state government to expedite the drainage revamp system. 
  • More will need to be done to build the flood-prone city’s defences. After the 2015 floods, experts had reasoned that planners should re-think construction projects on wetlands. 
  • Recently, the PM approved India’s first project to tackle urban floods
• Overall: 
  • The storage capacities of water bodies and water courses and/or associated wetlands, the flood plains, ecological buffer and areas required for specific aesthetic recreational and/or social needs must be managed in an integrated manner to maintain ecological balance.
  • Urban settlements, encroachments and any developmental activities in the protected upstream areas of reservoirs / water bodies, key aquifer recharge areas that pose a potential threat of contamination, pollution, reduced recharge and those endanger wild and human life should be strictly regulated.