In a report released by the India Meteorological Department (IMD) on May 27, the actual rainfall received by Kerala and Mahe during May 20 to 26 is recorded as 115.4 mm, a departure of 126% from normal rainfall. Kerala has been witnessing excessive summer rains all through March, April and May, bringing concerns of heavy rainfall and flooding during the monsoon, like it did in the years of 2018 and 2019. The IMD has predicted that the southwest monsoon will likely reach Kerala on May 31.
"The rainfall this summer is higher than what we received in 2018," says Abhilash, Department of Atmospheric Sciences, CUSAT (Cochin University of Science & Technology). That was the year Kerala received the worst flood in nearly a century, killing 483 people, over 140 others going missing, and causing severe damage to houses and properties.
Abhilash reckons the El Nino-Southern Oscillation (ENSO) has brought more rain-bearing clouds to the region. El Nino — a climate variability that results in abnormal warming of Eastern Pacific Ocean - would cause atmospheric circulation in ascending and descending directions, he says. "La Nina - the opposite condition of El Nino - is the ascending branch which comes to the Indian Ocean."
The pre-monsoon showers, coupled with the impact of the two recent cyclones of Yaas and Tauktae, had produced nearly 130% more rainfall than the normal. "Due to the impact of these cyclones, the monsoon may start on a weak note. That has been the pattern in previous years. So in the first week of June, it is not expected to be on a flood-making level. However, from the second week, normal rain is expected. And even if we receive heavy to extremely heavy rainfall for one or two days, along with the normal monsoon, it can be dangerous," Abhilash warns.
Due to the excessive summer showers, the land surface in the state has been already effected the way it normally is in June end. "The small flooding and localised waterlogging situation we witness in June-July has already happened after the summer rains. So a day or two of heavy rainfall coming along with a normal monsoon can create problems, and a flooding situation."
There is a limit to which dams can be used for flood control - only the bigger dams like Idukki and Idamalayar have the water capacity for it. "But of course, the timing of opening dams, drainage cleaning, all of it have to be factored in," Abhilash adds.