An extreme rainfall event due to climate change can cover 80 to 90% of Panjagutta area, according to research on impact of climate change on urban floods in Hyderabad. The research by BITS-Pilani, Hyderabad-campus scholar Vemula Swathi under K. Srinivasu Raju’s guidance shows how the city will be impacted as heavy rainfall events become inevitable due to climate change.
According to the author, the study covered stormwater drain network, modelling historic and extreme rainfall events, impact of future climate change and formulation of mitigation measures that urban planners can adopt.
The modelling also showed the impact on river Musi. “Results showed that changing rainfall and land use and land cover increased peak run-off by three times, and flood depth in river will increase by 22% from 1995 to 2031. In 2016, 48% of the city was highly vulnerable and in 2031, 51% of the city will be so,” says the research paper. The author suggests five detention ponds to combat increasing run-off reducing the high vulnerable area by 8% in 2016 and 9% in 2031.
“We wanted to prepare the ground work for policy makers to deploy strategies in managing future floods. Water is a boon. In the short term, it can cause damage but if we can save water, it will help us in the long run,” says Mr Srinivas Raju, who is leading the Information Technology Research Academy-sponsored project to study urban flooding and its impact.
“We are coming up with strategies to soak up water and reduce run-off. In the GHMC limits, we have 75-80% built-up area. Our suggestion is to tap these impervious surfaces and harvest rain water,” informs R. Madhuri, who is currently doing the research with Mr. Raju.
Hyderabad is no stranger to flood havoc having seen the Musi terror on September 28, 1908, and floods in August 2000 when 240-mm rainfall was logged in 24-hour span, and in October 2020, the city received 192 mm rain.
“As scientists are linking heavy rainfall events to climate change, we have used hydrology modelling and Global Climate Model to design how future run-offs can be managed. The investment may be high initially but it will be repaid within 15 years,” says Mr. Raju about the expansion of stormwater drains as well as developing new water harvesting structures across the city.
Existing stormwater network (SWN) is inadequate to carry run-off from future extreme daily rainfall of 431 mm, 564 mm and 693 mm. A huge capacity building (i.e. doubling the conveyance of existing SWN) is required to transmit the run-off from such events, predict the engineers.
