Mains Marks Booster     5th August 2023        
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Floods occur when a stream's discharge surpasses the capacity of its channel, causing excess water to flow over the banks and submerge the surrounding dry land.

Causes of Floods:

  • Natural Causes: These include heavy rainfall, cloud bursts, snow and ice melt, changes in river systems and catchment areas, sediment deposition in river beds, dam collapses, sea transgression during tropical cyclones, and tsunamis and landslides along rivers.
  • Anthropogenic Causes: These include deforestation (causing soil erosion and river silting), improper land use and farming practices (leading to soil and water flushing into rivers), and increased urbanization (reducing land's ability to absorb rain due to impermeable surfaces).

Consequences of Floods:

  • Negative Consequences: These include loss of life and property, agricultural disruption, habitat changes and destruction, disruption of communication and essential services, and the spread of water-borne diseases.
  • Positive Consequences: Floods can deposit fertile silt on agricultural fields, enhancing crop growth, and recharge groundwater levels.

Flood Distribution in India

  • In India, floods are a recurrent phenomenon affecting 12% (40 million hectares) of the country's geographical area. 
  • The most affected areas include Bihar (27% damage), Uttar Pradesh and Uttarakhand (33% damage), and Punjab and Haryana (15% damage). The Ganges-Brahmaputra-Meghna Basin accounts for nearly 60% of the country's total river flow and is a significant flood area. 
  • Other vulnerable regions include the Brahmaputra, Ganga, and Northwest River Regions, as well as Central and Deccan India. Due to their shallow basins, peninsular rivers and the eastern coasts, which are prone to cyclones, are also flood-prone.
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