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NATURAL DISASTERS

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By: Shankar Kailas Lokhande

Date: 31/05/2022

Introduction:

On 16 August 2018, severe floods affected the south Indian state Kerala, due to unusually high rainfall during the monsoon season. It was the worst flood in Kerala in nearly a century. Over 483 people died, and 15 are missing. About a million people were evacuated, mainly from ChengannurPandanadEdanadAranmulaKozhencherryAyiroorRanniPandalamKuttanadMalappuramAluvaChalakudyThrissurThiruvallaEraviperoorVallamkulamNorth ParavurChellanamVypin Island and Palakkad. All 14 districts of the state were placed on red 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 Indian government had declared it a Level 3 Calamity, or “calamity of a severe nature”.It is the worst flood in Kerala after the great flood of 99 that took place in 1924.

35 out of the 54 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, and for the first time in 26 years 5 gates of the Malampuzha dam of Palakkad were opened.Heavy rains in Wayanad and Idukki have caused severe landslides and have left the hilly districts isolated. The situation was regularly monitored by the National Crisis Management Committee, which also coordinated the rescue and relief operations as the dam got opened it has disrupted many lives living nearby.

With the recurrence of flood events in the state in the subsequent years, several studies which ensued explain the manifestation of westwardpropagating high frequency tropical atmospheric waves of characteristic phase speed of nearly 12 m/s, which originated near east equatorial Indian Ocean or tropical West Pacific and travelled to the east coast of Africa, and coincide with the same period of extreme rainfall events over Kerala. Moreover, the waves appeared as cyclonic and anti-cyclonic circulations trapped to the equator, which dilated the wind field and transported moisture as it propagated. The waves not only stimulated convection along its trajectory, but also ensured sufficient moisture availability. Therefore, the convective activities which intensified in the mid-troposphere, were the direct consequence of the equatorially-trapped high frequency waves, which played a significant role in driving the recurrent anomalous precipitation in the South Indian state.

2018 Kerala floods
DateJuly 2018 (2018-07) – August 2018
LocationKerala, India
CauseHeavy rain
Discharges
Landslide
Deaths483 dead,15 went missing
Property damageh400,000 crore (US$52 billion) (estimated)

Causes:

Kerala received heavy monsoon rainfall, which was about 116% more than the usual rain fall in Kerala, on the mid-evening of 8 August, resulting in dams filling to their maximum capacities; in the first 48 hours of rainfall the state received 310 mm (12 in) of rain. Almost all dams had been opened since the water level had 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 54 dams had been opened. The deluge has been considered an impact of the global warming.

Independent scientific studies conducted by Hydrology experts from IIT MadrasPurdue University, and IIT Gandhinagar concluded that it was the heavy downpour that resulted it the floods, and not the dam management. Based on a computer-simulation of flood storage and flow patterns by a team of researchers from IIT Madras and Purdue University, it was found that the devastation wrought by the floods cannot be attributed to the release of water from dams. Further, the scientists added that the odds of such floods were “0.06%” and no reservoir management could have considered such scenarios. Hydrology expert from IIT Gandhinagar, Prof. Vimal Mishra, identified four major factors for the floods. Unexpected above normal downpour, extreme rainfall events occurring almost across Kerala during the season, over 90% reservoir storage even before the onset of extreme rainfall events, and finally, the unprecedented extreme rainfall in the catchment areas of major reservoirs in the State led to the disaster. 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. 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 20–40 days period has favored convection in the tropics, the high-frequency mode correlates better with the anomalous precipitation during the intervals of extreme events.

Impact:

Over 483 people died, and 140 are missing, while The Economic Times reported that 33,000 people were 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 3,274 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 cancelled Onam celebrations, and the allocated funds have been reallocated to relief efforts.

On 12 August, Cochin International Airport, India’s fourth busiest in terms of international traffic, and the busiest in the state suspended all operations until 29 August, following runway flooding. All schools throughout the state except Sainik School Kazhakootam have been closed, and tourists have been dissuaded or banned from some districts due to safety concerns. Kochi Metro was closed briefly on 16 August, and later offered free service to aid those affected by the flooding. Due to heavy rain and rising water levels the southern railway had suspended train services on the Thiruvananthapuram-Kottayam-Ernakulam and Ernakulam-Shoranur-Palakkad sections.

  • Loss of Human life
  • Damage to Property
  • Destruction of Crops
  • Loss of Livestock
  • Deterioration of Health condition owing to waterborne diseases.

References:

 “Kerala floods: Death toll rises to 483000, says CM PinarayiVijayan”. New Indian Express. 30 August 2018. Retrieved 2 September 2018.

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