Tide–Rainfall Flood Quotient : Flood Estimation | UPSC
A new measure that can predict whether a city is prone to rain- or tide-based flooding
WHY IN NEWS:
Research showed Chennai was rainfall dominated and Mithi catchment was storm-tide dominated
SYLLABUS COVERED: GS 1 : 3 : Floods : Disaster Management
C40 CITIES REPORT OF 2018
- The C40 Cities report of 2018 notes that by 2050, over 570 low-lying coastal cities will face projected sea level rise by at least 0.5 meters.
- While the inland areas can be flooded due to the heavy rainfall, the coasts are threatened by the impact of tidal surges.
- A team from the Indian Institute of Technology Bombay 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.
- The above method used the past rainfall data, tidal data, and topography of the region you can apply this framework to pinpoint the major factor at play.
- The team selected three geographically diverse flood-prone coastal regions – Mithi Catchment in Mumbai, Maharashtra, Jagatsinghpur District in Odisha, and Greater Chennai Corporation in Tamil Nadu to test their new metric.
- The new method helped classify these regions into ‘storm-tide dominated’ or ‘pluvial (rainfall) dominated’ regions.
- In Mithi, they found a devastating impact of storm-tide reaching even up to a distance of 7 km from the coastal boundary.
- With Jagatsinghpur, high rainfall inundated several areas in the central region.
- The flood maps for Chennai showed that rainfall contributed to the flooding, especially in the northern and central regions.
- Though there was storm-tide in the eastern coastal region, it was in the ‘low’ hazard category.
- The above study concluded that Mithi catchment was ‘storm-tide dominated’, while Jagatsinghpur and Chennai were ‘pluvial dominated’.
- The metric can help disaster management experts in framing better flood risk management systems directed towards long term planning.
- For storm-tide dominated regions, severe flood hazard can be alleviated by building coastal defence structures such as closure dams, tide breakers, and storm-surge barriers at appropriate locations.
- The tide and surge forecasting systems in these regions should be equipped with state-of-the-art ocean circulation models.
- The IIT Bombay team has planned to apply this metric and calculate for the 76 coastal districts of India.
- It is a hugely time-consuming task as it involves various large data including rainfall, tide, landscape, and elevation of the area.
- The study now has given an idea that such long-term planning is needed especially in a country like India which has highly populated coastal cities.
SOURCES: THE HINDU | Tide–Rainfall Flood Quotient : Flood Estimation | UPSC