Case Study of the Day: Mitigation of Urban Flooding by Green Infrastructure: Surat

Context: To tackle floods, Surat City has adopted mitigation measures in form of ‘Green Infrastructure’, making it an effective ‘Flood Mitigation’ technique.

About Green Infrastructure for Flood Mitigation in Surat

• Causes of flooding in Surat
  • Accelerating impact of demographic growth, urbanization trends and climate changes.
  • Tides from Arabian Sea and Higher stream flow in Tapi River from Ukai Dam, increase risk of Floods.
  • Encroachment in the floodplain areas and silting in the river-bed have exacerbated the conditions.
  • Deficient urban drainage system, deforestation, and impervious surfaces due to urbanization have all added to Flood Risk.
• Under such an increased Risk of Flood, Green Infrastructure could be a feasible solution to aid mitigation efforts.
  • At the scale of a city or county, green infrastructure refers to the patchwork of natural areas that provides habitat, flood protection, cleaner air, and cleaner water.
  • At the scale of a neighborhood or site, green infrastructure refers to storm-water management systems that mimic nature by soaking up and storing water, such as rain gardens, permeable pavement, and green roofs.
  • Green infrastructure uses vegetation, soils, and natural processes to manage water and create healthier urban environments.
• Aspects of Green Infrastructure which can be implemented in Surat
  • Storm water Management
    • Storm water management means to manage surface run-off.
    • It is essential in urban areas where run-off cannot infiltrate because the surfaces are impermeable.
    • Storm water harvesting along both the sides of roads with the help of suitable, simple structures, would control storm water hazards.
  • Bios wales
    • It is a linear vegetative channel which help slow down the run-off and percolate into the ground.
    • Dense vegetation helps to infiltrate run-off effectively, hence native plants are preferable.
  • Green Roof
    • Is a thin vegetative cover over a roof to collect, filter and store rainfall, so as to retain and delay the rain water to end up getting discharged in storm water drains.
    • This prevents water-logging and eventually leads to flooding.
  • Permeable Paving
    • These allow water to percolate or travel through their structure into the underlying ground layer, thereby relieving pressures on traditional storm water management systems.
    • Permeable pavements are typically designed to handle as much as 70-80% of annual rainfall.

Conclusion

• With increasing pressures of Urbanisation and climate change risk, feasible solutions need to be sought to prevent impact of natural disasters.
• Green Infrastructure as a solution has been proven effective in cities of Rotterdam, London. Hence, the need to mimic the same in India, wherever cities are vulnerable.

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