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Current Affairs

Predicting vulnerability to rain or tide-based flooding

Date: 04 January 2021 Tags: Climate Change

Issue

The C40 Cities report notes that by 2050, over 570 low-lying coastal cities will face projected sea level rise, putting over 800 million people at risk from the impacts of rising seas and storm surges.

 

Details

  • To understand if a coastal city is more prone to floods caused by tidal events or extreme rainfall, a research team devised a new metric or measure called the Tide–Rainfall Flood Quotient.

  • It is very important to understand the main driver of the flooding events for effective disaster management.

  • Using the past rainfall data, tidal data, and topography of the region we can apply this framework to pinpoint the major factor at play.

  • The team selected three geographically diverse areas viz Mithi Catchment in Mumbai, Jagatsinghpur District in Odisha, and Greater Chennai Corporation (GCC).

  • The new method helped classify these regions into ‘storm-tide dominated’ or ‘pluvial (rainfall) dominated’ regions.

  • The plain based topography in Bay of Bengal region prevented easy flow of flood waters into the sea, which further increased the risks.

 

Observations

  • The Chennai flood maps showed that the rainfall was the major reason for floods in the northern and central parts of the city.

  • The study also identified that the Mithi catchment in Mumbai was storm-tide dominated and Jagatsinghpur and Chennai were pluvial dominated.

 

Preventing flooding

  • Structures such as rainwater storing tanks, overspill lakes, detention basins, and wetlands to be developed to prevent water from flooding.

  • Tide-storm forecasting system should be equipped with new technology that will predict risks based on ocean circulation patterns.

  • Building coastal structures such as closure dams, tidal breakers, storm-surge barriers etc that will prevent ocean water from entering into the land.