Increased urbanisation possibly causing heavy rainfall events in South India: UoH study

Increased urbanisation is possibly causing heavy rainfall events in cities


Increased urbanisation is possibly causing heavy rainfall events in cities of Tamil Nadu, Telangana and Kerala over the past few years, according to a study by city-based University of Hyderabad (UoH).

Several heavy rainfall events have been reported in cities of South India including the extreme rainfall that created havoc in Chennai and nearby areas in Tamil Nadu in December 2015, the heavy rain over Hyderabad and adjoining regions in Telangana in September 2016, and the extreme rainfall event in Kerala in August 2018, a release from UoH said on Tuesday.

These three states differ in their geographical locations, and also the season in which they receive rainfall.

A team led by Prof Karumuri Ashok from the Centre for Earth, Ocean and Atmospheric Sciences of the University of Hyderabad, examined whether a common factor, the changing land use land cover (LULC) in these states, has any implications for the heavy rainfall events.

Their study showed that the precipitation during heavy rainfall events in these states has significantly increased from 2000 to 2017.

Their findings were reported in the 'Quarterly Journal of Royal Meteorological Society' on May 18.

Using the land use land cover data from ISRO, and by conducting 2 km resolution simulation experiments of twelve heavy rainfall events over the states, the researchers found distinct LULC changes in these three states, which led to higher surface temperatures and a deeper and moist boundary layer, it said.

These in turn caused a relatively higher convective available potential energy and, consequently, heavier rainfall, according to the study.

It further stated that increasing urbanisation in Telangana and Tamil Nadu is likely to enhance the rainfall during the heavy rainfall events by 20 per cent to 25 per cent.

Prof Ashok felt that improving the density of observational rainfall and other weather parameters may help in forecasting extreme rainfalls at city level.