2018 Kerala floods
On 16 August 2018, severe floods affected the south Indian state Kerala, due to unusually heavy rainfall during the monsoon season.
[4] Over 483 people died,[5] and about one million[6][7] people were evacuated, mainly from Chengannur,[8] Pandanad,[9] Edanad, Aranmula, Kozhencherry, Ayiroor, Ranni, Pandalam, Kuttanad, Malappuram, Aluva, Chalakudy, Thrissur, Thiruvalla, Eraviperoor, Vallamkulam, North Paravur, Chendamangalam, Chellanam, Vypin Island, and Palakkad.
[18] With the recurrence of flood events in the state in the subsequent years, several studies have attempted to explain the behavior.
[19] On the evening of 8 August, Kerala received heavy rainfall which was 116% more than usual[clarification needed], resulting in dams filling to their maximum capacities.
Almost all dams had been opened since the water had risen close to overflow levels due to heavy rainfall, which flooded local low-lying areas.
[26] The prime reason for the anomalous rainfall in 2018 is the high-frequency mixed Rossby-gravity waves in the mid-troposphere triggered by the synoptic disturbances of the tropical Pacific.
[27][23] These high-frequency waves manifested as cyclonic and anticyclonic circulations and dilated the wind field to establish zones of convection in the tropics, as they propagated across the Indian Ocean basin.
Although the Madden-Julian Oscillation phase with 20-to-40-day period has favored convection in the tropics, the high-frequency mode correlates better with the anomalous precipitation during the intervals of extreme events.
Jacob P. Alex, an advisor appointed by the Kerala high court, alleged that the devastating floods of 2018 were the result of bad dam management by the state government.
[31][32][33][34] All 79 dams in the state were maintained with the objective to generate hydroelectricity or irrigation and controlling flooding wasn't their purpose.
The 'flood cushion' of reservoirs – the storage space earmarked in dams to absorb unanticipated high flows – needed review as per the latest guidelines," Alex wrote in his report.
"Sudden release of water simultaneously from different reservoirs, during extreme rainfall aggravated the damage," it said, adding that various alerts—blue, orange and red—had been issued not in accordance with the EAP guideline.
"No proper follow-up action and effective precautionary steps (especially for evacuating people and accommodating them in safe location) were taken after issuance of Red Alert," it said.
[44] The Kochi Metro closed briefly on 16 August, and later offered free services to aid those affected by the flooding.
[45] Due to heavy rain and rising water levels the southern railway suspended train services on the Thiruvananthapuram-Kottayam-Ernakulam and Ernakulam-Shoranur-Palakkad sections.
[52] According to the government, a total of 4,537 fishermen communities from Kollam and Thiruvananthapuram districts participated in the rescue operation with 669 fishing boats.
[154] UAE's President Sheikh Khalifa bin Zayed Al Nahyan ordered the formation of a national emergency committee to provide relief assistance to people affected by flash floods in the Indian state of Kerala.
According to a study by the Central Water Commission, the average cumulative rainfall of 3 days from 15 to 17 August 2018 was about 414 mm.
Even if the reservoirs had been a few feet below FL, the flooding conditions would not have changed much as the heavy rainfall continued for 3–4 days.
Ms. Anita cited ecological destruction caused by deforestation, harmful land use in the upland areas and sand mining in the streams and rivers as having contributed to the top soil run-off and siltation.
Echoing her views, experts at the National Institute of Technology, Calicut, (NIT-C) said it was usual for the water level in the rivers and domestic wells to fall after fluvial floods.
