Kerala witnesses above normal rainfall in three days

Kochi: Three days of torrential rain that left 15 people dead and triggered landslides, flash floods and extensive damage across Kerala have also sharply reduced the state's monsoon rainfall deficit.

According to India Meteorological Department (IMD) data, Kerala recorded 232% excess rainfall between July 31 and August 2. Meteorologists attributed the unusually intense short-duration rainfall to the combined impact of global warming and El Niño.

IMD data showed that the state's normal rainfall for the three-day period is 55.4 mm, but Kerala received 184.2 mm this year, registering rainfall that was 232% above normal, The New Indian Express reported.

Pathanamthitta was the worst-affected district, recording 533% excess rainfall over the three days. Against the normal 40 mm, the district received 253 mm of rain. Official sources said Vadasserikkara recorded 331 mm of rainfall on the night of July 31, while nearby Laha received 236 mm.

Thiruvananthapuram registered a 457% rainfall surplus, followed by Kozhikode (326%), Kollam (302%) and Kottayam (300%). Among the highest single-day rainfall totals, Vagamon received 314 mm, Vadasserikkara 331 mm, Vazhikkadavu 308 mm, and Ayyankunnu in Kannur 320 mm.

The IMD data also indicated that Kerala's monsoon rainfall deficit declined from 36% on July 29 to 24% on August 3.

However, C P Priju, Principal Scientist at the Centre for Water Resources Development and Management (CWRDM), said the brief spell of intense rainfall was unlikely to substantially recharge groundwater reserves. He explained that extreme rainfall over a short duration results in heavy surface runoff and flash floods, limiting groundwater infiltration and percolation. He also noted that while North Kerala usually receives more rainfall than the southern and central regions, the heaviest rain on July 31 and August 1 was concentrated over South and Central Kerala.

Researchers P. Vijayakumar and S. Abhilash, in a study, said low-pressure systems could continue to bring heavy rainfall, but warned that rising sea surface temperatures beyond a certain threshold could make rainfall more intense and concentrated in short bursts, increasing the likelihood of flash floods.

The study further noted that the increasing intensity of rainfall has heightened the risk of landslides along the highland and midland slopes of the Western Ghats in eastern Kerala. It added that extensive human interventions, particularly the large-scale conversion of hill slopes for cultivation, have further destabilised the terrain, making the region more vulnerable to landslides of varying intensity.