Though Kerala's Wayanad received more than five times the normal rainfall on Monday, leading to devastating landslides early Tuesday that killed at least 174, the district and the state have recorded a deficit in rainfall so far this monsoon season. According to data from the India Meteorological Department (IMD), Wayanad had a 15 per cent deficit in rainfall so far this season, and Kerala as a whole had a four per cent deficit. The monsoon season began in June and lasts four months. This unpredictability in precipitation, wherein very heavy rain happens in a short span of time while the rest of the days go relatively dry, has been an increasing trend in India, often attributed to climate change and as the cause of several disasters in recent years. While overall rainfall during the monsoon season over India as a whole has remained largely unchanged, the number of wet days during this four-month period has been on a decline. However, the lower number of wet days have been producing relatively larger amounts of rain. Some of these days have been yielding excessively high rainfall, resulting in largescale flooding - particularly in densely populated urban centres - and events like landslides or glacial lake outbursts in the Himalayan states. There has not been a single year since the 2013 Uttarakhand disaster that has gone by without at least one extreme rainfall event resulting in loss of life and property. Several of these events, like in Kashmir in 2014, Chennai in 2015, Gujarat in 2017, Kerala in 2018, and Himachal Pradesh last year, turned into major disasters that claimed hundreds of lives. In between, cities like Bengaluru, Mumbai and Chandigarh have also seen flooding due to excessive rainfall during short periods of time. Monday’s rainfall in Kerala was not extraordinary by these standards. Wayanad had 140 mm of rain on the day, while Kerala as a whole received about 118 mm of rain. These are high amounts, but not rare in Kerala during the monsoon season. The IMD defines rainfall more than 204 mm as extremely heavy rainfall. Monday’s rainfall in Kerala was thus classified only as “very heavy” rainfall, something that is not unusual in the state during the monsoon. Also, the event was limited to just one day. The 2018 incident in the state was much bigger in comparison. There were two spells of torrential rainfall in August, each one of them lasting for four-five days. The matter was compounded by the decision to release waters from some of the reservoirs in order to avoid dam-bursts. That had resulted in widespread flooding in each of the 14 districts of the state, its worst in at least the last 100 years. Rain had also triggered several landslides, including in Wayanad. At least 500 people were reported to have died in the floods and landslides. Kerala is among the three rainiest states in India, along with Meghalaya and Goa. However, it has been witnessing a declining trend in rainfall in recent years.
