kerala flood case study pdf

Wayanad tragedy: Landslides natural.. can’t prevent them but impact can be minimised

WAYANAD: The devastating landslides in Wayanad that killed hundreds and left thousands homeless have once again brought climate change to the limelight.

Amid the raging debate over whether the landslides were caused by natural fury or human intervention, TNIE brings together four experts to ponder over the causes.

In a freewheeling chat, Dr V Ambili, deputy director general, Geological Survey of India, Kerala unit, Dr K G Thara, former head, Disaster Management Centre, Kerala, Dr Sajin Kumar K S assistant professor in geology, University of Kerala, and Kerala State Landslide Advisory Committee member and Sridhar Radhakrishnan, environmentalist and policy observer, deliberate on the reasons, contributing factors, Kerala’s vulnerability, and disaster preparedness.

We’ve just witnessed two devastating landslides in Wayanad. What caused them?

Ambili: Many factors influence landslides. Kerala’s terrain, with its tropical humid climate, is prone to landslides. This landslide started at an altitude of 1,500m and later had a sharp drop to 800m. Besides intense soil formation and a sharp slope, the entire terrain is a tectonically active zone, especially towards the northern part. My study of the Chaliyar basin has clearly shown the river exhibiting old-age symptoms (like braiding and delta formation at the confluence with the sea) in the early stages of its course. The presence of a valley in Nilambur in the upper reaches shows signs of tectonic activity. It has been proved that the area comes under Zone-2 for neotectonic activity. This means there are fractures in the rocks that get reactivated under weather conditions (heavy rain).

What symptoms are usually seen in a landslide-prone area?

Ambili: The river is seen braiding here, in its upper reaches. Water always follows gravity. But if the river takes a turn, it is only because of a groove-like structure to facilitate it. During the landslide, the debris came down en masse, breaching the normal course.

What are the characteristics of such a zone?

Ambili: Weather is a major factor in determining landslides in a susceptible area. Other factors are slope, type of soil, structure of rocks, aspect etc. When there is a geological change, all such factors get reactivated. Water has ways to seep out of rocks as springs. But when the rain is heavy and continuous, it goes beyond the capacity of rocks to withhold water. When it crosses the threshold limit, these burst with disastrous effect.

Does human intervention figure in this?

Ambili: Human intervention is not the reason behind this landslide. The rocks couldn’t hold the water due to torrential rain in a place with a high slope.

What kind of human activities contribute to landslides?

Ambili: Quarries are a major contributor. We operate quarries without studying the geology of the area. There are many fractured quarries. The blasting that takes place in quarries will result in rock-fall in other locations. Plantation also contributes to landslides. It should be suited to the location. Plants should be chosen according to the soil and rock types. People have the habit of obstructing first-order streams to prevent them from entering their property. If we block the flow, the water seeps down and exerts pressure, resulting in smaller landslides. The landslides at Erattupetta were due to such human interventions. In Thrissur, we have seen people converting streams into pathways and roads.

Dr Thara, how do you see the current landslides from a disaster-management perspective?

Thara: Human interventions aggravate landslides. This landslide happened in a forest area above a populated area. The township was developed to facilitate plantations. The valley marked by such mono-crop cultivation dilutes the biodiversity required to prevent a landslide. There are large-scale human interventions in the name of promoting tourism. A lineament map gives a picture of rock-fractures beneath the soil. Calamities happen at places with maximum lineaments, the impact of which increases through human interventions.

You spoke about tourist inflow. Have we conducted any studies on the carrying capacity of Wayanad?

Thara: No, we haven’t. Any place with a slope greater than 20 degrees is landslide-prone. In Kerala, more than 50% of places are like that. When we construct multi-storey buildings atop hills, they exert greater pressure because of their weight, and landslides happen. Similarly, cutting the toe-end of the slope to build houses or canals also causes landslides.

The Wayanad landslide should have been declared a national calamity the very next day. The fact that they haven’t done it can be termed as apathy or a lack of political will. We may also have to term the construction of national highway as a national calamity... there are no safety precautions adopted.

Sridhar, in your opinion, has human intervention aggravated landslides at Mundakkai and Chooralmala?

Sridhar: I have gone through the landslide data between 1950 and 2018. Wayanad had a forest area of 85% in the 50s. By 2018, 62% of it was lost. At the same time, the plantation area has increased by 1,500% during the period. We should look at the Madhav Gadgil panel report in the light of the seven-decade long interventions made. According to him, 75% of the Western Ghats should be included in the list of ecologically sensitive areas. Both Meppadi panchayat (under which falls Mundakkai and Chooralmala) and Vellarimala were included in Zone-I. The areas where the landslides happened were tea estates. The second issue that we are clearly facing is the impact of climate change. According to a report by the Hume Centre for Ecology and Biodiversity, a staggering 4,000mm rain occured in areas where they had issued warnings, from June to July 31. Why then were no steps taken for preparation? Is this man-made or caused by nature? That climate change is human-induced, is a settled scientific position. To correct this, we need time. Instead, we are aggravating it all the more. For instance, if 10 lakh people had travelled to these landslide-prone areas, what does it mean?

Dr Sajin, what, according to you, are the causes for the landslides in Wayanad?

Sajin: I can emphatically say that it is not human-induced. I have been fully engaged with landslides, exclusively in the Kerala context, since 2018. There were 4,726 landslides — big and small — in the state in 2018 alone. Half of them occurred in Idukki district – 2,223 — including many in deep forests. How do we explain these? If these were induced by human interference, it could have occurred even in the months of March, April and May. However, 99.9% of our landslides are seen from June to October/November. Rain is hence the real trigger. But the rain that usually falls within a year’s time, is now pouring with high intensity in a much shorter period, and landslides happen.

Is it possible to predict landslides?

Sajin: We may be able to predict a landslide. However, no one can identify the exact route the runoff-rainwater would take. The best example of this was seen at Pettimudi. The same thing happened at Meppadi. Both Pettimudi township and Chooralmala are not landslide-prone areas. In addition to the landslide-susceptibility map, we also need a landslide-route map. Frankly, this is not a human-made landslide. But it doesn’t mean that human activities played no role at all.

Sridhar, if you believe that the landslides are down to human intervention, what do you have to say to Dr Sajin’s observations?

Sridhar: I didn’t say that the landslide happened because of human interventions. What I meant was the extent of casualty that occurred was purely due to human error.

What’s the role of human activities in the Wayanad landslides?

Sridhar: Though the landslides in Wayanad are a natural disaster, human actions significantly contributed to increased casualties. One major factor is the increasing tourism activities in ecologically vulnerable areas like Meppadi. Allowing construction in such areas is a grave human error that exacerbates the impact of landslides. Attributing these disasters solely to rain, as some scientists and the public do, oversimplifies the issue and turns it into a mere political statement. It’s crucial to acknowledge that climate change, driven by human interventions, does play a significant role in such events.

What are the solutions to avoid such occurrences in the future?

Ambili: The Geological Survey of India launched a National Landslide Forecasting Centre in Kerala on July 19. This system utilises historical landslide data from Kerala to provide more accurate landslide forecasts. The system has been operational in Darjeeling and Nilgiris since 2020 and it’s now a full-fledged system there. Trial runs for landslide alerts in Kerala began on July 20. The centre offers an online portal and application where both officials and the public can provide real-time data inputs, including rainfall observations, which is crucial for precise predictions. This initiative aims to enhance landslide preparedness and mitigation efforts through collaborative data-sharing and analysis. Reliable rainfall data is key for accurate landslide predictions. The primary data we use to generate predictions is the rainfall data provided by IMD (India Meteorological Department). In this case, based on the rainfall data provided by IMD at 2.30pm on July 29, we issued a green alert. However, there was a technical glitch. We are now planning to take data from other agencies too, as there are active rain gauges in the region. Making real-time satellite data available will also be crucial, allowing us to continuously monitor the situation.

Do you think insufficient funding for post-disaster research activities and limited sharing of scientific data between agencies pose a threat to mitigating disasters?

Sajin: There is a lack of funding for post-disaster research activities in India. While disasters in Kerala, like the Wayanad landslides, attract global research attention, there’s a noticeable absence of dedicated funding for such studies within the country. This hinders in-depth investigations and the development of locally relevant mitigation strategies. Sharing data between agencies is crucial for research activities. While international agencies openly share data, it remains unavailable in the public domain here. This hinders collaborative research and the development of effective solutions.

The experiences from the 2018 flood and the 2024 landslides indicate that rainfall predictions by IMD are unreliable…

Thara: The claims by Union Defence Minister Amit Shah that the Centre issued a landslide warning four days in advance are unscientific. Predicting a landslide four days prior is impossible. The IMD upgraded the warning to a red alert only after the landslide occurred, proving the claims to be false. Pinpointing the exact moment a landslide will be triggered is impossible, making the issuing of alerts extremely challenging. While we cannot prevent such disasters, we can mitigate their impact.

Sajin: Existing rain gauges were installed to support farming activities, and not specifically to monitor landslide-prone areas. Consequently, their placement and data collection may not be adequate to provide effective landslide warnings.

Ambili: Adequate and strategically located rain gauges are not there in critically vulnerable landslide-prone areas in Wayanad.

What can be done to avoid a repetition of such tragedies in future?

Ambili: Landslides are a natural phenomenon, and while we cannot prevent them entirely, we can take steps to minimise their impact. As experts suggest, reducing human interventions in ecologically sensitive areas can help avoid exacerbating these disasters.

Sajin: We should create awareness on the lines of what was done in the ‘80s and ‘90s. We should visit landslide-prone areas in April-May. Video classes by experts should be shown in schools. Students will spread the message on what needs to be done before and after a landslide. Such video demonstrations can be a viable solution if we don’t have funds for mock drills.

Do you mean to say that it should be made part of the curriculum?

Ambili: This has been implemented well in the northeastern states. Students are equipped to predict landslides when there is any suspicious movement and take precautionary action. Such training is necessary.

Can we predict landslides accurately using rain gauges?

Ambili: We cannot do it accurately. If heavy rain stops suddenly, a landslide may not happen. So, it is highly sensitive. When the alert is not up to the mark a few times, people will lose their trust.

Sajin: I beg to differ on that aspect. We now consider the rainfall of the previous day. Actually, the world over, what is being checked is the rainfall in the last 30 days. By analysing one month of rain, you will make a trial and error combination. We should look at how much rainfall is needed to saturate a certain amount of soil. When the level reaches 50%, you should give the first warning and ask people to evacuate.

Thara: Even if you give an alert when it reaches the threshold, you are going to speak to people who are asleep. An alert system is the most important factor. Unless the alert reaches the common man, nothing can be done. Secondly, rainfall is not the only factor. We construct national highways, homestays, and remove large amounts of soil. Each day, the vulnerability is increasing. I don’t think setting up rain gauges will solve the problem. People should know where to go when alerts reach them. There should be a socially-oriented disaster management plan.

But people wake up after the landslide and are clueless where to go...

Thara: In the matter of landslides, we have limitations. There is very little you can do after getting an alert but there is a lot of scope in things that can be done before that. In the case of a flood, you may get time but not in the case of a landslide. We should examine how many public offices are located in flood plains, which means an area of half a kilometre on either side. This area is for the river to flow freely or else it will bring huge rocks when it flows through a narrow strip. There should be efforts to relocate people from flood plains.

Dr Sajin, as a landslide expert, do you think quarrying and plantations contribute to landslides?

Sajin: If we look at Kavalappara, the other side is a rubber plantation. I could see rainwater pits after the landslide. The government supports rainwater pits but many don’t know where it should be done, scientifically. For rubber, farmers dig huge pits to hold water. After 20 years, the rubber plantation is destroyed. Earthmovers remove the root, totally disturbing the area. Instead, stubble mulching is the ideal method to be followed, where the root is retained. Plantation is a real cause, except for tea plantations.

Ambili: Usually, areas under tea-coffee cultivation are relatively less problematic. But when replantation happens, it is disturbing. Also, in places with more than a 20-degree slope, ideally, there should be no pits for rainwater-harvesting.

What about quarrying?

Sajin: All hard rocks seen in Kerala are at least 250 crore years old. But the top soil is only 10,000 to 15,000 years old. Studies have shown that the waves of uncontrolled blast cause a vibration of up to 200 metres. There will also be a lot of cracks due to quarrying. I won’t say it causes landslides, but it can facilitate the same. During monsoons, quarrying should be stopped. They can conduct sales, but shouldn’t go for blasting during the rainy season.

Thara: We cannot toe the approach that quarries are unavoidable as building materials are required for developmental activities. The Building Material Technology Council has come up with several alternatives to rock, sand, and other such building materials. There are many options available now. Why don’t we use them? We can look at options like fly ash and hollow bricks. In fact, we can re-use materials from demolished buildings and illegal constructions. We can also say that in landslide-susceptible zones, private buildings shouldn’t exceed a stipulated area. Also, do we need a six-lane road? We should look at alternatives, like improving the public transport system.

We all need good roads and we all travel by cars on these roads. So, is it correct to take such a hypocritical stand?

Sridhar: It is not a hypocritical stand. Per se, we are not saying no to roads. We need good roads. But what we now have are murderous roads where people die because of potholes.

Sajin: Those who oppose six-lane highways will go to Bengaluru via Tamil Nadu (laughs out).

Now that landslides are a reality, we can only adapt to them...

Sridhar: It’s not just about adapting. It’s about preparing for the same and creating resilience. Preparedness is an important aspect. The authorities should have data on who all are equipped to move out, who all should be evacuated, and how to facilitate the same. We have become experts in post-disaster management. We learnt that lesson the hard way. We have also become a sensitive society in providing relief. We should establish a similar mechanism for disaster-preparedness too.

Thara: We need measures in place to mitigate the same.

Sridhar: We should look at the fact that the government is planning a tunnel project in this area. The 6.9km four-lane road project will require blasting. There’s also a 1,000-acre project facilitated by the government — Asia’s biggest tourism destination with an airport — coming up in the same panchayat.

Will the proposed tunnel project accentuate the vulnerability of Wayanad?

Sajin: Not really. We now have many sophisticated technologies. If we drill using sophisticated technology, it won’t harm the environment. When a new path is created, we save a lot of money. If there are good roads, all of us will use the same. Let’s say there’s no tunnel, and if you want to go to Wayanad, will you risk it? We would be scared to go via the mountain pass. When you have a tunnel, you feel safe.

Sridhar: If you look at the alignment of the tunnel project, it’s not without a mountain pass. Once the project is completed, we save 22km of travel. You are going to spend about Rs 2,500 crore for that. Using this money, we could move at least 10,000 people. That should be the priority of the government.

The tunnel road connects three districts and the people of these districts need this... what you are saying may be considered as environmental fundamentalism…

Sridhar: No. I’m questioning developmental fundamentalism. Environmental fundamentalism is not going to kill you. Everywhere, developmental fundamentalism is what’s killing you now.

Sajin: We do need better roads and other infrastructure that are necessary for human beings.

TNIE team: Cithara Paul, Anil S, K S Sreejith, Unnikrishnan S, Shainu Mohan

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What to Know About the Deadly Landslides in Southern India

The death toll has steadily risen in Kerala state after heavy rain sent huge mudslides through a scenic area known as a tourist destination.

By Anupreeta Das Pragati K.B. and Hari Kumar

Reporting from New Delhi

Earlier this week, multiple landslides hit the Wayanad district of India’s Kerala state, killing at least 144 people and injuring hundreds of others. The landslides were caused by torrential rains that lasted for days, uprooting trees, burying villages and cutting off roads and communication lines. State officials described it as one of the worst natural disasters Kerala has ever witnessed.

Rescue workers continue to recover and identify bodies, and with more than 190 people still missing, the death toll is likely to rise. The state government has set up temporary hospitals and dozens of shelters, which are housing more than 8,000 displaced people. It also sent rations and clean water to the area, and declared a two-day mourning period on Tuesday.

What led to the disaster?

Wayanad is a hilly region in the northeastern part of Kerala known for its natural beauty and wildlife. A big tourist destination, its slopes are covered by tea and spice plantations and its valleys contain rice paddies.

But the elevation, the steepness of the slopes, a thick bed of loose soil that sits atop hard rock and rivulets created by heavy rainfall create the perfect conditions for landslides, said S. Sreekumar, a geologist who has worked with government bodies on disaster management. New construction and irrigation methods used by farmers have also compromised the natural drainage system, he said.

“There are high slopes and people are settled at the base of the slope,” Mr. Sreekumar said. Extreme and more frequent rainfall owing to climate change are also “a big contributor, no doubt about that.”

The area experienced unusually heavy rainfall for 48 hours, much more than what the India Meteorological Department had forecast.

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Temporal and spatial variations in rainfall erosivity on hainan island and the influence of the el niño/southern oscillation.

1. Introduction

2. materials and methods, 2.1. study area, 2.2.1. daily rainfall data, 2.2.2. enso indicators, 2.3. methods, 2.3.1. calculation of the re, 2.3.2. evaluation of the suitability of the re models, 2.3.3. spatial interpolation analysis method, 2.3.4. time-series change analysis method, 2.3.5. correlation analysis method, 3.1. evaluation of the suitability of the re calculation models, 3.2. change in re, 3.2.1. relationships among rainfall, erosive rainfall, and re, 3.2.2. spatiotemporal variation in re, 3.3. characteristics of the enso and its effect on re, 3.3.1. temporal distribution of different enso periods, 3.3.2. correlation between re and the enso, 3.3.3. effect of the enso on re, 4. discussion, 4.1. evaluation of the suitability of the re calculation model, 4.2. characteristics of variations in re, 4.3. re is affected by enso, 5. conclusions, supplementary materials, author contributions, data availability statement, acknowledgments, conflicts of interest.

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Lu, X.; Chen, J.; Guo, J.; Qi, S.; Liao, R.; Lai, J.; Wang, M.; Zhang, P. Temporal and Spatial Variations in Rainfall Erosivity on Hainan Island and the Influence of the El Niño/Southern Oscillation. Land 2024 , 13 , 1210. https://doi.org/10.3390/land13081210

Lu X, Chen J, Guo J, Qi S, Liao R, Lai J, Wang M, Zhang P. Temporal and Spatial Variations in Rainfall Erosivity on Hainan Island and the Influence of the El Niño/Southern Oscillation. Land . 2024; 13(8):1210. https://doi.org/10.3390/land13081210

Lu, Xudong, Jiadong Chen, Jianchao Guo, Shi Qi, Ruien Liao, Jinlin Lai, Maoyuan Wang, and Peng Zhang. 2024. "Temporal and Spatial Variations in Rainfall Erosivity on Hainan Island and the Influence of the El Niño/Southern Oscillation" Land 13, no. 8: 1210. https://doi.org/10.3390/land13081210

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Kerala flood case study

Kerala flood case study.

Kerala is a state on the southwestern Malabar Coast of India. The state has the 13th largest population in India. Kerala, which lies in the tropical region, is mainly subject to the humid tropical wet climate experienced by most of Earth’s rainforests.

A map to show the location of Kerala

Eastern Kerala consists of land infringed upon by the Western Ghats (western mountain range); the region includes high mountains, gorges, and deep-cut valleys. The wildest lands are covered with dense forests, while other areas lie under tea and coffee plantations or other forms of cultivation.

The Indian state of Kerala receives some of India’s highest rainfall during the monsoon season. However, in 2018 the state experienced its highest level of monsoon rainfall in decades. According to the India Meteorological Department (IMD), there was 2346.3 mm of precipitation, instead of the average 1649.55 mm.

Kerala received over two and a half times more rainfall than August’s average. Between August 1 and 19, the state received 758.6 mm of precipitation, compared to the average of 287.6 mm, or 164% more. This was 42% more than during the entire monsoon season.

The unprecedented rainfall was caused by a spell of low pressure over the region. As a result, there was a perfect confluence of the south-west monsoon wind system and the two low-pressure systems formed over the Bay of Bengal and Odisha. The low-pressure regions pull in the moist south-west monsoon winds, increasing their speed, as they then hit the Western Ghats, travel skywards, and form rain-bearing clouds.

Further downpours on already saturated land led to more surface run-off causing landslides and widespread flooding.

Kerala has 41 rivers flowing into the Arabian Sea, and 80 of its dams were opened after being overwhelmed. As a result, water treatment plants were submerged, and motors were damaged.

In some areas, floodwater was between 3-4.5m deep. Floods in the southern Indian state of Kerala have killed more than 410 people since June 2018 in what local officials said was the worst flooding in 100 years. Many of those who died had been crushed under debris caused by landslides. More than 1 million people were left homeless in the 3,200 emergency relief camps set up in the area.

Parts of Kerala’s commercial capital, Cochin, were underwater, snarling up roads and leaving railways across the state impassable. In addition, the state’s airport, which domestic and overseas tourists use, was closed, causing significant disruption.

Local plantations were inundated by water, endangering the local rubber, tea, coffee and spice industries.

Schools in all 14 districts of Kerala were closed, and some districts have banned tourists because of safety concerns.

Maintaining sanitation and preventing disease in relief camps housing more than 800,000 people was a significant challenge. Authorities also had to restore regular clean drinking water and electricity supplies to the state’s 33 million residents.

Officials have estimated more than 83,000km of roads will need to be repaired and that the total recovery cost will be between £2.2bn and $2.7bn.

Indians from different parts of the country used social media to help people stranded in the flood-hit southern state of Kerala. Hundreds took to social media platforms to coordinate search, rescue and food distribution efforts and reach out to people who needed help. Social media was also used to support fundraising for those affected by the flooding. Several Bollywood stars supported this.

Some Indians have opened up their homes for people from Kerala who were stranded in other cities because of the floods.

Thousands of troops were deployed to rescue those caught up in the flooding. Army, navy and air force personnel were deployed to help those stranded in remote and hilly areas. Dozens of helicopters dropped tonnes of food, medicine and water over areas cut off by damaged roads and bridges. Helicopters were also involved in airlifting people marooned by the flooding to safety.

More than 300 boats were involved in rescue attempts. The state government said each boat would get 3,000 rupees (£34) for each day of their work and that authorities would pay for any damage to the vessels.

As the monsoon rains began to ease, efforts increased to get relief supplies to isolated areas along with clean up operations where water levels were falling.

Millions of dollars in donations have poured into Kerala from the rest of India and abroad in recent days. Other state governments have promised more than $50m, while ministers and company chiefs have publicly vowed to give a month’s salary.

Even supreme court judges have donated $360 each, while the British-based Sikh group Khalsa Aid International has set up its own relief camp in Kochi, Kerala’s main city, to provide meals for 3,000 people a day.

International Response

In the wake of the disaster, the UAE, Qatar and the Maldives came forward with offers of financial aid amounting to nearly £82m. The United Arab Emirates promised $100m (£77m) of this aid. This is because of the close relationship between Kerala and the UAE. There are a large number of migrants from Kerala working in the UAE. The amount was more than the $97m promised by India’s central government. However, as it has done since 2004, India declined to accept aid donations. The main reason for this is to protect its image as a newly industrialised country; it does not need to rely on other countries for financial help.

Google provided a donation platform to allow donors to make donations securely. Google partners with the Center for Disaster Philanthropy (CDP), an intermediary organisation that specialises in distributing your donations to local nonprofits that work in the affected region to ensure funds reach those who need them the most.

Google Kerala Donate

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SAR based flood risk analysis: a case study Kerala Flood 2018

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Study report: kerala floods of august 2018 (september, 2018).

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1.0 Introduction

Kerala State has an average annual precipitation of about 3000 mm. The rainfall in the State is controlled by the South-west and North-east monsoons. About 90% of the rainfall occurs during six monsoon months. The high intensity storms prevailing during the monsoon months result in heavy discharges in all the rivers. The continuous and heavy precipitation that occurs in the steep and undulating terrain finds its way into the main rivers through innumerable streams and water courses.

Kerala experienced an abnormally high rainfall from 1 June 2018 to 19 August 2018. This resulted in severe flooding in 13 out of 14 districts in the State. As per IMD data, Kerala received 2346.6 mm of rainfall from 1 June 2018 to 19 August 2018 in contrast to an expected 1649.5 mm of rainfall. This rainfall was about 42% above the normal. Further, the rainfall over Kerala during June, July and 1st to 19th of August was 15%, 18% and 164% respectively, above normal. Month-wise rainfall for the period, as reported by IMD, are given in Table-1.

Due to heavy rainfall, the first onset of flooding occurred towards the end of July. A severe spell of rainfall was experienced at several places on the 8th and 9th of August 2018. The 1- day rainfall of 398 mm, 305 mm, 255 mm, 254 mm, 211 mm and 214 mm were recorded at Nilambur in Malappuram district, Mananthavadi in Wayanad district, Peermade, Munnar KSEB and Myladumparain in Idukki district and Pallakad in Pallakad district respectively on 9 August 2018. This led to further flooding at several places in Mananthavadi and Vythiri in Wayanad district during 8-10, August 2018. Water was released from several dams due to heavy rainfall in their catchments. The water levels in several reservoirs were almost near their Full Reservoir Level (FRL) due to continuous rainfall from 1st of June. Another severe spell of rainfall started from the 14th of August and continued till the 19th of August, resulting in disastrous flooding in 13 out of 14 districts. The water level records at CWC G&D sites for some of the rivers in Kerala are given at Annex-I. As per the rainfall records of IMD, it has been found that the rainfall depths recorded during the 15-17, August 2018 were comparable to the severe storm that occurred in the year 1924.

1.1 Earlier floods in Kerala

The 1924 witnessed unprecedented and very heavy floods in almost all rivers of Kerala. Heavy losses to life, property and crops etc. had been reported. The rainstorm of 16-18, July 1924 was caused by the South-west monsoon that extended to the south of peninsula on 15th July and caused rainfall in Malabar. Under its influence, heavy rainfall occurred in almost entire Kerala. The area under the storm recorded 1-day maximum rainfall on 17th of July, 2- day maximum rainfall for 16-17, July 1924 and 3-day maximum rainfall for 16-18, July 1924. The centre of the 1-day and 2-day rainstorm was located at Devikulam in Kerala which recorded 484 mm and 751 mm of rainfall respectively. The centre of 3-day rainstorm was located at Munnar in Kerala which recorded a rainfall of 897 mm in 3 days.

The fury of 1924 flood levels in most of the rivers was still fresh in the memory of people of Kerala, the year 1961 also witnessed heavy floods and rise in the water levels of reservoirs. Usually in the State, heavy precipitation is concentrated over a period of 7 to 10 days during the monsoon when the rivers rise above their established banks and inundate the low lying areas. But in 1961, floods were unusually heavy not only in duration, but also in the intensity of precipitation. During the year 1961, the monsoon started getting violent towards the last week of June and in the early days of August, the precipitation was concentrated on most parts of the southern region of Kerala. By the first week of July, the intensity gradually spread over the other parts of the State and the entire State was reeling under severe flood by the second week of July. The worst affected area was Periyar sub-basin and it also impacted other sub-basins. Many of the important infrastructures like highways etc were submerged. After a brief interval, by the middle of July, the monsoon became more violent, affecting the northern parts of the State. The average rainfall was 56% above normal. The maximum daily intensities recorded at four districts in 1961 are given in Table-2.

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Kerala Floods 2018: Impacts and Lessons Drawn

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Kerala, the southwest coastal state of India which ranks high on the Human Development Index, became vulnerable to severe flooding during the southwest monsoons of 2018. The state faced the worst floods in the century due to above-normal rainfall from June to August 2018. The above-normal rainfall was supplemented by a lack of integration of sustainable development practices and disaster risk management strategies. The floods affected all the districts of the state and led to the loss of over 400 precious lives along with extensive damage to infrastructure and property. It also triggered about 341 landslides in the area. The community including fishermen and women-centric organizations like Kudumbashree participated actively in responding to the disaster. Technology including WhatsApp, GIS, and crowdsourcing was used actively by the community during the search, rescue, and relief phase. The floods highlighted many constraints like lack of proper management and monitoring of critical natural resources such as water and land which left the state unprepared for major disasters caused by natural hazards. The disaster also highlighted crucial lessons to be adopted by other coastal states of the country which are expected to face increased flooding in the coming times due to climatic changes.

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Walia, A., Sharma, P., Nusrat, N. (2022). Kerala Floods 2018: Impacts and Lessons Drawn. In: Singh, A. (eds) International Handbook of Disaster Research. Springer, Singapore. https://doi.org/10.1007/978-981-16-8800-3_188-1

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• DOI: 10.5194/HESS-2018-480
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The Kerala flood of 2018: combined impact of extreme rainfall and reservoir storage

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• Published 14 September 2018
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