Flood is a state of higher water level along a river channel or on coast leading to inundation of land that is not normally submerge. In India, 40 million hectares out of a geographical area of 3290 lakh hectares is prone to floods. Moreover, every year, 1600 lives are lost and the damage caused to crops, houses and public utilities is Rs. 1800 crores due to floods.

The main causes for floods are as follows:

The rivers bring heavy sediment load from catchments. These, coupled with inadequate carrying capacity of rivers are responsible for causing floods.

• Some of the general causes are drainage congestion, erosion of river-banks, silting in deltaic areas
  
  
• Moreover, about 75% of the annual rainfall in India is concentrated in 3-4 months of the monsoon season. As a result, there is very heavy discharge from rivers during the period causing widespread floods.
  
  
• Further, cyclones, cloud bursts, storm surge cause flash floods and lead to huge loss of life and property.
  
  
• Lastly, in urban areas the urban flooding is caused by increasing incidence of heavy rainfall in a short period of time, indiscriminate encroachment of waterways, inadequate capacity of drains and lack of maintenance of the drainage infrastructure. For ex.- Chennai floods.
  
  

Steps to mitigate flood vulnerability are as follows:

• There is a need for identification and marking of flood prone areas and preparation of close contour and flood vulnerability maps.
  
  
• Further, this must be followed by implementation of the schemes for expansion and modernisation of the flood forecasting and warning network, execution of flood protection and drainage improvement schemes
  
  
• The focus must also be on development of hard management techniques like dams, embankments or artificial levees
  
  
• Further, flood walls/ River defences/ Coastal defences can be built around settlements to protect them from floods.
  
  
• Lastly, the focus must also be on afforestation, proper land use management
  
  

Thus, the causes of the floods being natural and man made requires, thus to control and mitigate the same requires interdisciplinary approach.