Natural Disasters

Kerala deluge: Flooded districts were rain-deficit 24 hours ago

Till August 6, Kerala reported a deficit of 10% in its seasonal monsoon rainfall; by August 7, several districts had been issued red alerts 

By Richard Mahapatra
Published: Friday 07 August 2020
In Pala, a town in Kerala, during 2018 floods. Photo: Wikimedia Commons

The India Meteorological Department (IMD) bulletin on monsoon progress in Kerala on August 6, 2020 pointed to significant rain deficit in almost all districts / sub-divisions. Barely 24 hours later, however, things turned around: Most of the rain-deficit districts were flooded due to extreme rainfall.

Till August 6, Kerala reported a deficit of 10 per cent in its seasonal monsoon rainfall. By IMD definition, deficit of up to 19 per cent from the long period average is considered normal. But, rainfall in four districts — Idukki, Malappuram, Thrissur and Wayanad — were reported officially ‘deficient’ or reporting a deficit over 20 per cent from average.

Of the state’s 16 meteorological sub-divisions / districts, 10 reported deficit rainfall over the seasonal average ranging from 1 to 32 per cent.

By August 7, however, these districts had been issued red alerts. According to IMD alerts, these districts are likely to receive over 204.5 millimetres of rainfall in the next 24 hours.

Just as the IMD updates poured in, news of devastating landslides and floods overwhelmed the state. The reason: Spells of extremely heavy rainfall over 24 hours.

Idukki district reported 20 per cent departure from the normal monsoon; in fact, it was speculated that the region may see a drought-like condition. But on August 7 morning, extreme rainfall — exact measure is yet to be officially released — led to a massive landslide in Munnar, killing 12 people. At least 57 are reportedly missing.

IMD issued a red alert for both Idukki and Wayanad, warning of an above-200 mm rainfall in the next 24 hours.

Wayanad reported the highest departure from normal average seasonal rainfall till August 6 — 32 per cent less than normal. Similarly, Malappuram, which reported seasonal deficit of 23 per cent till August 6, is expected to be hit by extreme rainfall in the next 24 hours, according to IMD.

Another district that experienced deficit rainfall earlier but now faces threat of floods is Thrissur. It reported 30 per cent deficit rainfall — before the tables turned. The IMD has warned of extremely heavy rainfall (above 200 mm) in over 24 hours.

That Kerala is heading towards a severe flood situation is clear from another development. Current rainfall has been triggered due to a low pressure in the Bay of Bengal. But another low pressure is also brewing in the Bay. Its impacts will be felt after August 9.

In 2018, Kerala witnessed its worst flood in a century. That flood was also triggered by erratic spells of extreme rainfall, besides other reasons such as mismanagement of water discharge from dams.

Between August 8 and August 15, 2018, each of the 14 districts of the state recorded much more than normal rainfall

The worst hit were the districts of Idukki (679 mm), Wayanad (536.8 mm), Mallapuram (447.7mm), Kozhikode (375.4 mm) and Palakkad (350 mm), each of which received rains that were  several times more than normal.

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