In late July 2018, severe flooding affected the Indian state of Kerala due to unusually high rainfall during the monsoon season. It was the worst flooding in Kerala in nearly a century. Over 445 people died, 15 are missing within a fortnight, while at least 280,679 people were evacuated, mainly from Chengannur, Pandanad, Aranmula, Aluva, Chalakudy, Kuttanad and Pandalam. All 14 districts of the state were placed on high alert. According to the Kerala government, one-sixth of the total population of Kerala had been directly affected by the floods and related incidents. The Union government had declared it a Level 3 Calamity or 'Calamity of a severe nature'.
Thirty-five out of the forty-two dams within the state were opened for the first time in history. All five overflow gates of the Idukki Dam were opened at the same time, for the first time in 26 years. Heavy rains in Wayanad and Idukki have caused severe landslides and have left the hilly districts isolated. The situation was regularly monitored by the Prime Minister and the National Crisis Management Committee coordinated the Rescue and relief operations.
Kerala received heavy monsoon rainfall on the mid evening of August 8 resulting in dams filling to capacity; in the first 24 hours of rainfall the state received 310 mm (12 in) of rain. Almost all dams have been opened since the water level has risen close to overflow level due to heavy rainfall, flooding local low-lying areas. For the first time in the state's history, 35 of its 42 dams have been opened. Most of the regions affected by this monsoon were classified as ecologically-sensitive zones (ESZs) by the Western Ghats Ecology Expert Panel, the Gadgil Committee. Most of the recommendations and directions by the committee was either neglected or rejected. Chairman of the committee Madhav Gadgil accused the state government and its irresponsible environmental policy for the recent landslides and floods. He called it a "man-made calamity".
The Government of Kerala argued in the Supreme Court that the sudden release of water from the Mullaperiyar Dam by the Tamil Nadu government was one of the reasons for the devastating flood in Kerala. The Tamil Nadu government rejected the argument saying that Kerala suffered the deluge due to the discharge of excess water from 80 reservoirs across Kerala, spurred by heavy rains from within the state; It also argued that the flood surplus from the Idukki dam is mainly due to the flows generated from its own independent catchment due to unprecedented heavy rainfall while the discharge from Mullaperiyar dam was significantly less.
Though it is difficult to attribute a single event to climate change, its possible role in causing the heavy rainfall event over Kerala cannot be discarded . Recent research indicates that rising temperatures have led to huge fluctuations in the monsoon winds carrying the moisture from the Arabian Sea, resulting in heavy-to-extreme rains over the Western Ghats and central India, lasting for two to three days.
A state official told AFP that 370 people have died, while The Economic Times has reported that 33,000 people have been rescued. The Kerala State Disaster Management Authority has placed the state in a red alert as a result of the intense flooding. A number of water treatment plants were forced to cease pumping water, resulting in poor access to clean water, especially in northern districts of the state. Over 5,645 relief camps have been opened at various locations to accommodate the flood victims. It is estimated that 1,247,496 people have found shelter in such camps. The flooding has affected hundreds of villages, destroyed an estimated 10,000 km (6,200 mi) of roads and thousands of homes have been damaged or destroyed. The Government has cancelled Onam celebrations, whose allocated funds have been reallocated to relief efforts.
Being instructed by the Cabinet Secretary, Senior officers of Defence Services, NDRF, NDMA and Secretaries of Civilian Ministries conducted meetings with Kerala Chief Secretary. Following the decisions taken during these meetings, the Centre launched massive rescue and relief operations. In one of the largest rescue operations, 40 helicopters, 31 aircraft, 182 teams for rescue, 18 medical teams of defense forces, 58 teams of NDRF and 7 companies of Central Armed Police Forces were pressed into service along with over 500 boats and necessary rescue equipments. Totally, 60,000 people are rescued from marooned areas and was shifted to relief camps.
Additionally, 52 rescue teams of central forces including units of the Indian Army and the Indian Navy and state governed forces like Kerala Police and Kerala Fire and Rescue Services assisted the civilian administration in rescue work and restoration. In addition to the 10 teams of the National Disaster Response Force, four additional teams were airlifted from Guntur and Arakkonam to assist the Ernakulam district administration. Union Minister for Home Affairs Rajnath Singh conducted an aerial survey of Idukki and Ernakulam districts along with Chief Minister Pinarayi Vijayan.
Fisherman from Thiruvananthapuram and Kollam districts took part in the rescue operations with their boats and rescued several who were trapped in their homes by rising waters. The Kerala Government announced financial aid in return for their support and effort in the rescue mission. Mananthavady and Vythiri in the hilly Wayanad district have been totally cut-off, with roads washed away. According to the latest official figures, more than 800,000 people have been lodged in over 4,000 relief camps across 14 districts. On August 19, the state's Chief Minister Pinarayi Vijayan vowed "to save even the last person stranded."
At a press conference on 11 August, Chief Secretary Tom Jose said, "Things are well under control. The government is on top of the situation." Prime Minister Narendra Modi conducted an aerial survey and offered federal support to Kerala. Chief Minister Pinarayi Vijayan described the floods as "something that has never happened before in the history of Kerala" and placed some of the blame on neighbouring Tamil Nadu for not releasing excess water from the State-operated Mullaperiyar dam, which worsened the situation.