rajamala landslide case study

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• Published: 13 July 2022

The tale of three landslides in the Western Ghats, India: lessons to be learnt

• R. S. Ajin 1 ,
• D. Nandakumar 2 ,
• A. Rajaneesh 3 ,
• T. Oommen 4 ,
• Yunus P. Ali 5 &
• K. S. Sajinkumar 3  

Geoenvironmental Disasters volume  9 , Article number:  16 ( 2022 ) Cite this article

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In recent years, landslides have become a typical monsoon calamity in the Western Ghats region of Kerala, India. In addition to property damage, heavy rainfall (36% above normal) and multiple landslides (4728) killed 48 people in 2018. This tendency continued throughout the monsoon seasons of 2019, 2020, and 2021, resulting in the deaths of over 100 people. Anomalous precipitation is ascribed to the frequent development of low-pressure in the surrounding oceans. Using ground real data and satellite imagery, we evaluated the features of three large landslides in the state of Kerala, which occurred during the monsoon season of 2021. Our investigation found that the Kokkayar landslide was triggered by anthropogenic-related agricultural activities, the Plappally landslide by geomorphic and tectonic processes as well as human involvement, and the Kavali landslide by forest fragmentation with dense vegetation on thin soil. The triggering mechanism for all three of these landslides, however, is the intense rainfall of 266 mm in less than 24 h. Thus, an accurate and precise forecast of rainfall can be used to define a threshold for an early warning, which will be vital for saving lives.

Introduction

Catastrophic landslides have become a common monsoonal phenomenon in India’s southwest state of Kerala, which is located in the foothills of the prominent mountain chain, the Western Ghats. The anomalous rainfall of 2018, which was about 36% more than the normal rainfall (Vishnu et al. 2019 ), triggered 4728 landslides (Hao et al. 2020 ) and killed 48 people. These landslides occurred in a single storm-event i.e., 16th August 2018. The following years saw further landslides, with the monsoon season of 2019 witnessing disastrous landslides such as the one at Puthumala, which killed 17 people, and the Kavalappara, which killed another 59 people (Sajinkumar and Oommen 2020 ; Wadhawan et al. 2020 ). Both these landslides occurred on 8th August 2019. The Pettimudi landslide of 6th August 2020 was the most tragic one that killed 70 people and devastated several hutments in a tea plantation region (Achu et al. 2021 ; Sajinkumar and Oommen 2021 ). Year 2021 also experienced cataclysmic landslides on 16th October with the most disastrous ones being at Kokkayar in Idukki district and Plappally and Kavali, near Koottickal in Kottayam district. All these devastating landslides that occurred since 2018 showed an uneven geographic distribution (Fig.  1 a, b), pointing to the possibility that many parts of the Western Ghats are susceptible to landslides, though these landslides are located along the same valley (Fig.  1 c). In this study, we narrate the ground real data and interpretation of high-resolution remotely sensed images of the three landslides- Kokkayar, Plappally and Kavali (Fig.  2 , a, b, c) that occurred in 2021. We also employed ethnographic techniques, such as in-depth interviews with elderly impacted individuals, to learn about their shared experiences. These three landslides are amongst the tens of landslides in the vicinity of the study area (Fig.  3 ). The reason for selecting these three landslides is because of their catastrophic nature resulting in many human casualties. We believe that the narrative of these three landslides applies to other landslides that occurred in the immediate vicinity of this area.

(Source: Google Earth) ( b ) Study area with elevation map draped over hill shade map showing major landslides since 2018 (Elevation data is ALOS PALSAR) ( c ) Google Earth image showing the spatial distribution of these three landslides along a valley

Location map ( a ) South India

Field photos of ( a ) Kokkayar landslide ( b ) Plappally landslide ( c ) Kavali landslide

A distant view of the hills in the study area showing several landslides

Site and situation of the landslides

Kokkayar landslide.

Kokkayar landslide (9°34′21''N; 76°53′13''E) of Peermade taluk in the Idukki district of Kerala has killed seven people and completely destroyed seven houses. The dimension of this landslide is 500 m (length) × 40 m (avg. width) × 1 m (avg. thickness). Rubber plantations predominantly occupy the area with intermittent clusters of mixed vegetation. The area is utilized for agriculture through terrace cultivation with the cut slope protected by rubble masonry wall. Rain pits were constructed on this slope. Houses are constructed by the cut and fill method but without any support in the cut slope. Most of the houses have dug wells and the depth to water level is shallow (< 2 m) whereas during the landslide these were found overflowing (as per local witness), pointing to the fully saturated column of soil. Numerous springs spout from this area (Fig.  4 a). This spouting phenomenon existed before landslides because dwellings have drains to flush away storm water (Fig.  4 b). These observations indicate that a seasonal first and/or second-order stream flows through this area, which might have been modified during the course of agriculture and/or habitation. A few fresh gullies have been formed, to which water is now confined.

a Spouting of spring at Kokkayar landslide ( b ) A demolished house having provisions for draining storm water ( c ) A highly-weathered joint in the country hornblende biotite gneiss ( d ) Soil profile showing dislodged material, lateritic soil, saprock and weathered bedrock

The in-depth interviews with the local people revealed that the vegetation, mainly rubber trees were clear-felled after slaughter tapping a few years prior to the event. Contour bunding and rain-pits were made prior to replanting the rubber saplings. These interventions seem to have taken place ignoring the natural hydrological requirement of letting the first/second order streams to have its free flow channels. Such interventions may have contributed to destabilizing of soil on the slopes.

The area is characterized by outcrops of hornblende biotite gneiss. The general trend of this foliated rock is 173°/35 W. The preponderance of feldspar in this rock and its subsequent alteration through weathering has resulted in the formation of clay. The rock is highly jointed, and weathering is found to be extensive along these joints (Fig.  4 c). The crown of the landslide is occupied by bouldery outcrops of this rock with no soil cover. Hence, during monsoon, all the water in the crown part has surcharged the immediately downslope column of lateritic soil causing an increase in pore-water pressure. Near the flanks of the landslide, the soil profile shows dislodged soil followed by lateritic soil of 1 m thickness and another 1 m thick saprolite (Fig.  4 d). This is further followed by bedrock. The dislodged material was finally dumped into the Pullakayar, a tributary of Manimala River.

Plappally landslide

Plappally landslide (9°37′3''N; 76°52′21''E) in Kanjirapally taluk of Kottayam district has killed four people and demolished two buildings. This landslide of 500 m (length) × 20 (avg. width) × 1 m (avg. thickness) was initiated in a rubber plantation whereas its runout stretches through areas of different land use types. In the Google Earth image (before landslide), the upslope in which the landslide occurred is confined is a truncated spur and its right boundary is marked by a straight lower-order river course, indicating a lineament (Fig.  5 a). Due to the broader surface area of this spur, the run-off zone is more extensive. The storm water when crossing the barren rock outcrop, situated downslope, facilitates sudden surcharge to the thin veneer of soil lying immediately downslope. It is in this zone the recent landslide was initiated. The surcharge zone can be well seen in the high-resolution (3 m) False Colour Composite (FCC) of Planet Lab (Fig.  5 b). The truncated spur together with the bulged foothill suggests this as a paleo-landslide, within which the recent landslide occurred.

a Google Earth image showing a distant view of Plappally landslide showing a suspected lineament, remnants of paleolandslide and its associated truncated spur ( b ) 3 m resolution FCC of Planet Lab image showing the landslide runout and its surcharge area ( c ) Storm water gushing through the uprooted house location ( d ) The ruins of the devastated house, which was constructed along the course of a lower-order stream ( e ) Seepage along the joints of hornblende biotite gneiss

This landslide is also confined to a lower-order stream course. The two buildings, which were destroyed, were constructed precisely on the river course. Water gushes through this during the monsoon (Fig.  5 c), whereas it is dry during the non-monsoon season (Fig.  5 d) showing its seasonal nature. But seepage can be seen along the joints of the country rock, hornblende biotite gneiss (Fig.  5 e). Here again, in the upper slope, where the houses stood before the landslide, plantation with young rubber trees existed, which indicates a similar influencing factor like at Kokkayar.

Kavali landslide

Six people died and one house was demolished by the Kavali landslide, which is 250 m (length) × 15 (avg. width) × 2 m (avg. thickness) in dimension. Hornblende biotite gneiss is the country rock, which is highly weathered and jointed. The attitude of this highly foliated rock is 315°/80NE. Here too, spring water is tapped for domestic purposes. The destroyed house was constructed in a cut-slope, but the cut-slope is still retained after the landslide. The cut-slope profile exhibits lateritic soil, saprolite, and weathered bedrock. The area is characterized by thick vegetation when compared to the sparse vegetation in the adjacent area. This thick mixed vegetation with rubber plantation is the major crop, followed by nutmeg, arecanut, and teak. Google Earth image (Fig.  6 a) also revealed thick vegetation. A Normalized Difference Vegetation Index (NDVI) map was created using the high-resolution Planet Lab image to understand the area’s land use. NDVI revealed that the landslide occurred in a densely vegetated area when compared to other areas consisting of a wide variety of land uses like moderate vegetation, grassland, barren outcrop, and built-up. Usually, landslides are less reported in densely vegetated areas (cf. Alcantara-Ayala et al. 2006 ; Reichenbach et al. 2014 ). In contrast to this, a recent study by Lan et al. ( 2020 ) suggests that a densely vegetated slope decreases its stability. This study has been concurred with by the recent findings of Hao et al. ( 2022 ) wherein most of the landslides that occurred in Kerala during 2018 are spatially associated with forest land. However, a closer look at Fig.  6 a, b reveals forest fragmentation and breaking-off of the contiguity of the forest canopy, creating scattered and fragmented forest islands. Studies reveal that such a process could compromise landscape integrity (Ramachandra and Kumar 2011 ; Batar et al. 2021 ).

a Google Earth image showing a distant view of Kavali landslide and forest fragmentation ( b ) NDVI of Kavali area depicting dense vegetation in landslide occurred area

The Western Ghats, especially its southern part encompassing the entire state of Kerala, witness landslides often during monsoon season. Since 2018, the noteworthy feature of the monsoon has been that it triggers landslides during the sporadic high-intensity rainfall (cf. Vishnu et al. 2019 , 2020 ; Yunus et al. 2021 ; Sajinkumar et al. 2022 ). Though several studies have been conducted in this region, and measures suggested were not adopted, we present here specific omnipresent reasons that facilitate landslides in this region.

Introspection of land use policy

The recent landslide susceptibility map of Kerala (cf. Sajinkumar and Oommen 2021 ; Escobar-Wolf et al. 2021 ) shows an area of 3300 and 2886 km 2 as highly and moderately susceptible to landslides, respectively. It will be an arduous task to implement stringent measures such as habitation- and construction-free zones in these areas. However, some of the landslide-facilitating practices that are common, may be inadvertently so, can be averted. Kerala is predominantly an agrarian state, and the general agricultural land use seen are cash crops, with rubber plantations occupying the midlands and tea, coffee and cardamom in the highlands. All the three landslides occurred in the midlands, especially where rubber plantation dominates the land use. The construction of rain pits is a common practice in almost all rubber estates. Major disturbance to the slope stability occurs when fully matured rubber trees are slaughtered after their life span of ~ 20 years, and fresh saplings are planted in a broad pit of 1 m 3 size. Rain pits are also dug here. The method of stubble mulching is not practiced here and large area of land will be disturbed when the trees are uprooted using machinery. Hence, avoiding rain pits, planting pits, and promoting stubble mulching practice will help reduce the probability of landslide occurrences. Avoiding rain pits and planting pits in susceptible landslide areas will help increase run-off rather than infiltration. In addition, all agricultural techniques on the hilly slope affects the lower-order drainage, by obstructing it with rubble-masonry walls, redirecting it to a more hazardous slope, or by constructing houses. These lower-order courses, except in thickly vegetated forest areas, are usually seasonal, and during monsoon season, the normal flow of water is thus disturbed by these practices. Hence, a stringent land use policy to avoid such practices in agricultural fields is a pressing requirement.

Rainfall- the sole triggering factor

As mentioned, these three landslides were also triggered by a sporadic-high intensity rainfall of > 266 mm in a single day (Fig.  7 ) but with a 5-day antecedent rainfall of only 109.9 mm. The comparatively higher rainfall of 48.8 (2nd October), 45.4 (8th October and 69.6 mm (11th October) might have saturated the soil column and the 16th October anomalous event was sufficient enough to trigger landslides. In order to limit the risk of rainfall-induced landslides, an accurate and exact rainfall forecast that allows for the issuance of early warnings based on the rainfall threshold of the area is essential (Weidner et al. 2018 ). The sparse density of rain gauges and manual operation methods make things difficult. For e.g., the rain gauge station nearest to these three landslides is Kanjirapally, approximately 10 km away from this landslide, which is grossly inadequate to capture the micro-climatic conditions of the susceptible areas. Moreover, this rain gauge station is a manual one with daily rainfall recording on the succeeding day at 8.30 am ( www.imd.gov.in ). Having automated rain gauges that report rain information near real-time will be critical for developing early warning systems.

Hyetograph of Kanjirappally rain gauge, which is the nearest to the landslide affected area. Note the prominent 266 mm rainfall on the landslide day

Soil thickness and soil-rock interface plane

The hilly area of the entire state of Kerala is characterized by a thin veneer of unconsolidated soil, resting above the massive Precambrian crystalline rock except for plateau regions like Munnar and Nelliyampathy (Sajinkumar and Anbazhagan 2015 ). Usually, the glide plane of the landslides will be the contact plane of these two litho-units (cf. Istiyanti et al. 2021 ). Thus, wherever the landslide occurs, the bedrock will be exposed, which can be seen in all these three landslides. Hence, along with the understanding of landslide susceptibility, the soil thickness of the area and the saturation capacity of that soil column have to be investigated. The contact between these two litho-units is stable in a plain or gentler slope (Fig.  8 a) whereas it will be in a meta-stable position when in a steep slope (cf. Getachew and Meten 2021 ; Puente-Sotomayor et al. 2021 ) (Fig.  8 b). This equilibrium will be lost when the soil column is saturated by water during the monsoon season (Fig.  8 c).

Sketch depicting the contact between unconsolidated soil and massive crystalline Precambrian rocks along the Western Ghats part of Kerala. ( a–c ) shows the different stages of stability of these two lithounits

The three landslides that occurred on 16th October 2021 are located in the same valley, and were triggered by a high-intensity rainfall of 266 mm in one day. These similarities are never the same when conditioning factors are analyzed. The steep slopes of the hilly regions where all three landslides occurred originally contained natural contiguous forests that may have held the thin soil and regolith layer together. The modern landscape, however, is dominated by human interventions such as the replacement of natural vegetation with plantations, highways, and human settlements. These measures facilitated the triggering of the landslides by a sudden storm of intense rainfall (cf. Lahai et al. 2021 ). However, a closer check using ground reality and satellite photographs revealed that the Kokkayar landslide was completely caused by humans, whereas the Plappally landslide was also affected by geomorphic and tectonic causes. The third site, the Kavali landslide, was caused by forest fragmentation on the forest island. Consequently, regardless of the contributing components, the common and vital feature to be researched is the rainfall dynamics, which can be converted into early warning systems, thereby saving countless lives.

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Acknowledgements

The authors thank Kerala State Disaster Management Authority (KSDMA) for facilitating fieldwork in these areas. Jobin Sebastian, a freelance photographer and paraglide trainer, is highly thanked for providing photos (Figs. 1 d and 2 ). The lab work was carried out at the Laboratory for Earth Resources Information System (LERIS) housed at the Department of Geology, University of Kerala. LERIS is a collaborative initiative of Indian Space Research Organization and University of Kerala.

The author declare that there is no funding in the manuscript.

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State Emergency Operations Centre, Kerala State Disaster Management Authority (KSDMA), Thiruvananthapuram, Kerala, 695033, India

Sree Sankaracharya University of Sanskrit, Kalady, Kerala, 683574, India

D. Nandakumar

Department of Geology, University of Kerala, Thiruvananthapuram, Kerala, 695581, India

A. Rajaneesh & K. S. Sajinkumar

Department of Geological and Mining Engineering and Sciences, Michigan Technological University, Houghton, MI, 49931, USA

Indian Institute of Science Education and Research, Mohali, Punjab, 140306, India

Yunus P. Ali

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RSA-Field visit, manuscript writing DN-Field visit, manuscript writing AR-Data analysis, figure preparation TO-Data analysis, figure preparation, manuscript writing YPA-Data analysis, figure preparation, manuscript writing KSS-Field visit, Data analysis, figure preparation, manuscript writing, supervision

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Ajin, R.S., Nandakumar, D., Rajaneesh, A. et al. The tale of three landslides in the Western Ghats, India: lessons to be learnt. Geoenviron Disasters 9 , 16 (2022). https://doi.org/10.1186/s40677-022-00218-1

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DOI : https://doi.org/10.1186/s40677-022-00218-1

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Rajamala Landslide: Continuation of a Never-ending Landslide Series

Journal of the Geological Society of India

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Landslides are the common phenomena in the hilly terrain of Western Ghats region due to the heavy rainfall. The occurrence of landslides in the study area Sakleshpura and Belthanggudi Talluk in Karnataka state is quite less in comparison to Himalayan region. In the year 2018, during monsoon season the study area faced divesting floods and landslides. The aim of this study is to identify the landslide prone zones using Frequency Ratio Model with the help of ArcGIS software. The factors considered for this study are slope, soil, drainage density, distance from drainage and rainfall. All the spatial data have been calculated using frequency ratio model and each grid factor has been summed up into three categories such as high, moderate and low hazard zone. The results of this study reveals that that 160 sq.km areas is under very low with landslide density (LD) of 0.01, 894 s.km area is under medium zone with LD of 0.02, 75.36 sq.km area is under high hazard zone with LD of 0.05. The study also reveals that the soil is more vulnerable factor for landslide on the basis of frequency ratio value flowed by rainfall, slope, distance from drainage and drainage density in the study area. The final output of the map can be helpful for the local government of the study area.

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10 August 2020

Rajmala: a deadly landslide in Kerala, India

Posted by Dave Petley

Please see an update on this landslide, now termed the Pettimudi landslide, here.

On Thursday 6 August 2020 a large landslide occurred at Rajmala near to Munnar, Kerala in western India.  The landslide, which was triggered by the same spell of intense monsoon rainfall that was a factor in the Air India Express airliner accident on the same day , struck the accommodation of workers from a tea estate.  At the time of writing, 43 bodies have been recovered from the site .  Reports suggest that a further 28 people are likely to be missing, giving a total toll of 71 people, although there is always considerable uncertainty.

So far I have found little information about the specifics of the landslide, and images that provide a decent oversight are difficult to obtain.  The best I have found to date is this one, from India Life and Times :-

The Rajmala landslide in Kerala, India. Image from India Life and Times .

This appears to be a large, flow type slide in highly weathered soil. although better images are needed to understand it properly.

This is the largest landslide in India so far in the 2020 monsoon, although there are several weeks of rain to come yet.  Large landslides in Kerala have happened previously .  On the same day in 2019 a large landslide occurred at Kavalaparra in Kerala, killing 59 people .

Quickslide 1: another deadly landslide in South Korea

On Friday 7 August 2020 another large, mobile landslide struck South Korea.  On this occasion the landslide was located in Gokseong County, South Jeolla, killing five people.  Korea JooAng Daily has a good image of the landslide:-

The landslide in Gokseong County, in South Korea on Friday 7 August 2020, which killed five people. Image from Korea JooAng Daily .

A tropical cyclone is expected to bring more heavy rainfall today.

Quickslide 2: a seismically-induced rockslide in the Sawtooth Mountains in Idaho

Yahoo has news of a seismically-induced rockslide in the Sawtooth Mountains in Idaho on 7 August .  The video is cool , although I recommend sound off (for the sake of those around you and for your own sanity):-

Posted in: landslide report 5 Comments/Trackbacks »

The date given here is seems incorrect. The landslide was earlier believed to have happened in early hours of Friday, Aug 7. However, according to this report published today ( https://indianexpress.com/article/explained/how-kerala-munnar-landslide-happened-6549373/ ) it occurred on Thursday night at 10.45. This also gives more info, including saying the slope was 40 degrees and rainfall figures.

This area is part of Western Ghats and has been experiencing frequent fatal landslides. We have published this Guest Article on landslide mechanisms in Western Ghats by Prof Putty, see: https://sandrp.in/2020/08/08/landslides-in-kodagu-western-ghats-a-critique-of-gsi-report/ . Feedback on that is welcome.

Himanshu Thakkar ( [email protected] ), SANDRP

The rockslide in the Sawtooth Mountains was worth watching. Shame about the total morons with a very limited vocabulary, doing the ‘commentary’.

Please write about the failure mechanism of Pettimudi Landslip of 2020

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One year of Pettimudi landslide; a scar yet to be healed

Alphonsa p george, 06 august 2021, 01:03 pm ist.

Shanmughanathan

O ne year has passed since a fatal landslide struck the village of Pettimudi in Kerala’s Idukki district. The Geological Survey of India had reported after a probe that the mishap had resulted from the extremely heavy rainfall received in the area over a week. The relentless rainfall triggered the landslide which wrecked lanes of houses in Pettimudi and killed over 70 people. Majority of the people affected were descendents of dalits from Tamil Nadu who were brought here to work in tea plantations during the British period.

When the National Disaster Response force (NDRF) decided to cease the search for dead bodies in Pettimudi after recovering 65 of them, Shanmughanathan was not willing to return. Even though he looked for the remains of his elder son Dinesh Kumar (22) for almost six months after the incident, he could not find anything yet.

Shanmughanathan who was working as a cashier in a bank at Marayoor has three children. The landslide had snatched the lives of his two sons_ Dinesh and Nitheesh. The two had gone to Pettimudi to celebrate the birthday of a relative but they did not return, says Shanmughanathan.

While he was able to trace the dead body of his younger son, Nitheesh who had then been laid to rest along with 65 others at the Rajamala hills, it is the search for the elder Dinesh that has not been fruitful. On every holiday Shanmughanathan used to visit Pettimudi to continue searching for his elder son's remains but the efforts have all been in vain. Dinesh was a Computer Science graduate and had been working from home during the pandemic. His brother Nitheesh was pursuing Mechanical Engineering in St Joseph Engineering College.

As per customs of their community, if children died before their marriage, some ceremonies tied to funeral rites had to be done at Rameswaram. Shanmughanathan had visited Rameswaram recently to perform those rituals for his sons.

Shanmughanathan's agony has not ended there. He has not been able to obtain the death certificate of Dinesh and because of which deposits and insurance claims of his son could not be completed. As per norms, the police or hospital authorities are responsible for reporting the accidental deaths after which the concerned authority issues a death certificate. According to Munnar Grama Panchayat Secretary, death certificates had been issued already for all the deaths that were reported.

Pettimudi then and now (swipe the bar to see the change)

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Munnar landslide: 17 bodies recovered on Sunday, death toll rises to 43

Munnar, Idukki: The death toll in the massive landslide that destroyed a row of houses of tea estate workers at Pettimudi near Rajamala in Kerala's Idukki district rose to 43 on Sunday with 17 more bodies being retrieved from the debris.

According to the government, 78 people were staying at the spot where the tragedy occurred. While 12 were rescued, the search is on to find the rest.

Three days after the settlements were swept away by devastating landslides at Pettimudi near Rajamala, authorities have now decided to take help of sniffer dogs to trace the persons buried under the debris.

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Austerity marked even the final rites of the people who had lived a life of struggle with limited resources in a row of small housing units near tea plantations. The 26 bodies recovered on Saturday were buried in three pits at a ground near the Rajamala Hospital after their postmortem was completed.

The eight people whose bodies were found on Saturday were identified as Vijila (47), Kuttiraj (48), Pawan Thai (52), Shanmukha Ayyan (58), Manikandan (20), Deepak (18), Prabha (55) and Bharathi Raja (35).

One of the dead on Friday was identified on Saturday as Saroja, 58.

Ministers M M Mani and E Chandrasekaran are camping in the area to oversee the search operations.

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Kannan Devan Hill Plantations Company has announced financial assistance of Rs 5 lakh each to the families of the deceased.

There were 78 people in the five rows housing units that were destroyed in the landslide that occurred early on Friday morning. All were from Tamil Nadu. Twelve people were rescued in the initial search operations.

19 students went missing

Nineteen school children went missing in the Pettimudi landslide tragedy on Friday morning. These children, who lived in four rows of small homes meant for tea plantation workers, were students of various schools in the Munnar region. The bodies of two of them have been recovered.

The students who had gone missing were: S Lavanya, Hema, R Vidya, Vinodini, Janani, Rajalakshmi, Priyadarshini (Little Flower High School, Munnar), Jagadeeshwari (Govt High School, Munnar), Vishal (St Mary's UPS, Marayoor), Lakshyasree, Ashwanth Raj (Carmelagiri Public School, Korandakkad), Lakshnashree, Vijayalakshmi, Vishnu (ALPS, Rajamala), Joshua, Sanjay, Sindhuja, Gausika, and Shivaranjini (Fathima Matha High School, Chinnakanal).

The bodies of Sindhuja and Sanjay have been recovered.

Victims buried together

The 26 people whose bodies were recovered after the landslide at Pettimudi were buried in Rajamala itself.

After conducting the postmortem at the Rajamala Estate Hospital, the bodies were taken in batches of five each to a ground about a kilometre away and buried together in three pits 15 metres long and 6 feet deep.

The last rites were held without public mourning or rituals, except for the tears of relatives.

There are 39 more people still missing after the landslide.

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Some say that the remains of the dwelling units that were washed away by the landslide were found in the Perumbankuthu river in Mankulam. According to locals, the bodies of many of the victims may have been taken away by the Pettimudi river.

The search operations were being carried out by carefully removing slush, mud and stones with bulldozers.

Kuttiraja and his wife Vijila were the first to be found on Saturday. The bodies of the couple, who were sleeping in the same bed, were found 10 feet apart. The body of their son Manikandan was found a little later. Their other son Deepak was also found dead.

The eighth body on Saturday was found late in the evening when the search operations were about to be called off.

Many relatives of the victims arrived from Tamil Nadu, resulting in large crowds in Pettimudi. Many came to Kerala on a two-day pass.

Rescue workers risking life

"It is raining continuously with raindrops that seem like threads. Sometimes, the fog is so heavy that you cannot see the person standing next to you," said a rescue worker at Pettimudi. "Occasionally, there are small noises from Anamudi, which make you to look up at the hill in fear, to ensure that there are no signs of another landslide."

Rescue workers are putting their lives at risk while looking for those who were trapped in the landslide in Pettimudi on Friday morning.

It's been more than 48 hours since a 200-member rescue team, including the fire brigade, the police and the National Disaster Response Force (NDRF), began the search operations. Activists of political and voluntary organisations have also joined them.

There was a landslide on Saturday morning, too, as it continued to rain on Friday night. Rainwater flowing like flood also posed a challenge to the rescue workers, who had to work in slush that was knee-deep in some places.

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The dwelling units of the tea plantation workers who got buried in the landslide were at the edge of a three-acre area filled with stones and mud.

The search was carried out using seven bulldozers. Trees had to be cut in marshland areas to make way for bulldozers to help with the search for bodies.

The location of houses destroyed by the landslide was determined with the help of locals to find those trapped.

The search operations could not continue overnight as power was not restored in the area.

Even though the National Disaster Response Force and the fire brigade took over the search and rescue work from the locals on Friday morning itself, the operations have been hampered by inclement weather, delaying the retrieval of bodies.

Locals put all their might

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"Murukesha, make tea." Anandan, a native of Pettimudi, has for many years started his day with tea from Murukesha's canteen. But, on Friday morning, when he came for his daily cup, all that he saw were debris and rocks in the area where the canteen once stood.

A landslide early in the day had destroyed the canteen and a few rows of housing units meant for tea plantation workers in Pettimudi, trapping 78 residents. Anandan screamed.

By then, people from nearby places had reached the spot.

All of them stood there motionless for a few moments, not knowing what to do. As they gathered their wits, they started looking for their acquaintances and loved ones among the rocks and slush caused by incessant rains.

That is how the rescue operations started after the landslide.

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Plantation workers from four smaller rows of houses near the five rows that perished in the disaster were the first to reach for rescue work. They were then joined by jeep drivers from Idamalakkudi doing rounds to see if roads had been damaged after they heard the loud rumblings and creaks typical of landslides on Thursday night.

They began searching for people with whatever instruments and equipment they could find.

Some locals walked 14 km to inform forest department officials in Rajamalai about the tragedy. By the time the officials arrived, the locals had rescued six people who were found half-covered in mud and debris. They also found three bodies.

Soon, about 20 people from the tribal areas of Idamalakkudi reached the spot in jeeps and by running through the forests.

Later, the first fire brigade service arrived from Marayoor.

However, other vehicles could reach the spot as roads were damaged. It took an hour more for an ambulance to reach Pettimudi after the roads were cleared of stones, slush and fallen trees.

In the absence of sufficient spades, locals started clearing the mud and slush using pots and other vessels to look for buried people. They paved a path using aluminium sheets and tins.

Some stones were so huge that even 10 people could not move them. The locals would then lower a bamboo stalk into the mud, remove it and look at the tip to see if there was any sign of blood.

The locals did all they could, but they were helpless amid the rubbles and debris caused by nature’s fury.

It took another 20 hours for a team of experts to join the search. By then, any signs of life had faded away.

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The devastating Pettimudi landslides in Kerala: Were vulnerabilities ignored?

Karuppayi was fast asleep when she woke up to her neighbour screaming. It was around 10.30 pm on August 6. The neighbour’s scream forced two of Karuppayi’s male relatives to step out of their house to check what was happening. But they went back to sleep thinking the commotion may have been due to the overflowing river in the valley below. 

She, however, couldn’t go back to sleep. An hour or so later, Karuppayi heard the screams again and came out of the house. Within minutes, the back wall of her house was reduced to dirt, collapsing under the weight of a heap of soil that rained down on the village.  Filled with terror, Karuppayi ran to the road. 

The 54-year old woman is one of the few survivors of the landslide which occurred at Pettimudi in Kerala’s hill district of Idukki on August 6. The tragedy has claimed the lives of 62 people, including 19 children. Around eight people are still missing, with their bodies yet to be retrieved.  

While Karuppayi managed to escape, she lost 13 members of her family including three of her children, six grandchildren, and her younger sister. She and her siblings were living in layams (housing quarters for tea estate workers) adjacent to each other. 

Read: Koovi, the dog who waited days for owner, helps find toddler’s body in Idukki landslide

“We were living there for years, used to work in the tea estates. Everything is gone...,” 

Karuppayi tells TNM, unable to finish her sentence, breaking into tears. 

The landslide in Pettimudi comes nearly a year after a similar tragedy at Kavalappara in Wayanad district on August 8, 2019. The landslide in Kavalappara left 46 people dead, while the bodies of 13 people are yet to be recovered. 

Pettimudi was believed to be a ‘safe zone’, not prone to any disasters in the past, say residents and authorities. Was it really a safe zone? So how and why did the landslide occur? 

Tremors and hydraulic pressure 

CS Soman, a retired geologist of the Centre for Earth Science Studies, says that tremors triggered by hydraulic pressure could have caused the landslide. The hydraulic pressure was in turn caused by days of intense rainfall in the area. 

“Large, broken boulders can be found in the debris or the sort of materials that came down in the landslide. These boulders generally can be found only in fracture zones. This implies that this was a tectonically active area (tectonic zone) sometime in the geological past. The tectonically active area must have been dormant or stable for a long period, but it won’t be the same forever,” he says, adding that the trigger for the landslide in Pettimudi was incessant and extremely heavy rains.

Tectonics is the movement of the earth’s surface. It is as a result of the tectonics that continents move and earthquakes, tsunamis occur and mountains are formed.

Soman says that fractures which appeared on the tarred road surface on the south of Pettimudi and on the Munnar road is evidence of the tremors.

“Such fractures appear only during the time of tremors big or small. The whole of Munnar, in a way, are tectonically small active regions,” says Soman. However, as seismic activity below 3 on the richter scale isn’t measured, a number of these minor quakes are never recorded, he explains, “The conventional approach in India is that the richter scale is fixed at three and hence the tremors below that won’t be measured.”

Arguing that the tremors in Pettimudi would have been below 3 on the richter scale and therefore not recorded, the geologist says, “If there were no tremors there won’t be any fractures on the road.” 

The region, where the landslide took place, is a valley, explains Soman. The upper part of the valley merges with a saddle (the lower area that connects two mountain ranges). “Every saddle in a hill range is always a tectonic zone,” observes Soman, stating the sheer amount of rainfall received in the fractured area could have triggered the landslide. 

Pettimudi falls under the region of Eravikulam National Park. As per the data provided by the National Park, the rainfall on August 3, four days prior to the landslide, was 111 millimeter. The following day it was 195 millimeter, while on August 5, the region recorded 93mm of rainfall. August 6 saw intense rainfall, with 309 millimeter recorded in a single day. Thereafter, on August 7, Pettimudi and the surrounding region received 157 millimeter of rainfall.

Sajin Kumar, Associate Professor of Geology at Kerala University, also says that in the history of landslides in Kerala the major push has been heavy downpour. “The high rainfall in a short period should have played the triggering role,” Sajin says of the Pettimudi landslide. 

“Also the area where the landslide occurred was a flat-topped hill prior to the disaster. In a flat-topped hill the water collected would come down to the hill during a downpour, unlike in a three dimensional hill where the water would scatter all the way. In the case of a flat-topped hill, maximum water would be pooled in one gully,” he adds.

Age of rocks

The second factor that led to the landslides, Sajin says is the age of rocks. “We have very old rocks that are 200 crore years old. The rocks get saturated with water depending on its solid nature. If the soil is rooted in one meter, rainfall of two or three days is enough for it to get saturated. Once it's saturated, water won’t be able to permeate. And what happened in Pettimudi is that the huge volume of water collected at one point of the hill pushed the saturated soil which could be the main factor that led to the landslide.”

Sajin also says that from the curved portion of the hill where there landslide occurred in Pettimudi it could be assessed that a landslide had occurred some 50 years ago at the spot, prior to the planting of tea saplings in the region.

Several regions of the state are landslide prone areas, he says, citing the 4726 landslides that occurred in 2018 of which 800 were in the forest regions. Of the 4726 landslides, over 2500 occurred solely in Idukki.

Need for large-scale mapping and real-time data

Countering the claims of residents and authorities, Sajin Kumar says that Pettimudi must be a vulnerable area only. However, given the scale of maps, places like Pettimudi, a village in Idukki, may not be clearly mapped as a vulnerable area.  

“The question is how much real earth is represented in a map. We need maps that will cover all the red zones in it," he argues.

Soman says that large, flood zonation maps need to be prepared. “Large maps should be prepared featuring many things that hitherto have not been factored, flood zonation maps also need to be prepared, and three erosion zones in coastal areas should be demarcated. These maps are needed to prepare hilly terrains, inlands, and coastal regions for any future calamities,” he says.

Sajin suggests the need for an early warning system to minimize the effects of natural disaster.

“If there is one meter thickness of soil on a rock, 100 millimeter of rainfall in three days is a trigger for a landslide. This is called early warning. For this we need a network of rain gauges which can provide data in a real-time manner. In Kerala the rain gauges, mostly those under the government agencies, collect the rainfall data a day after the rainfall occurred. What we lack is real-time data and the best thing can do is to provide an early warning to minimize the effects of natural disasters,” he suggests.

‘Human responsibility high’

Usha Soolapani, an environmentalist points out that the Western Ghats has become more vulnerable despite claims to the contrary. “It has been two-three years that the state has been witnessing severe drought and heavy rains. No study has happened about the nature of the soil. In Puthumala and Kavalappara where the landslide occurred last year, there were quarries functioning nearby. We keep saying that the Western Ghats is stable despite the vulnerability having increased,” Usha Soolapani says, adding, “We are ignoring that climate change has affected the earth, making it more vulnerable. It’s not about hilly districts like Idukki or Wayanad, but the whole state is vulnerable. In Pettimudi, our presumption was that it was safe because of tea plantations. But we never went back and checked after all these years.” 

Soman says Pettimudi’s vulnerability was everywhere on the earth’s surface but was overlooked by everyone.

“No one can deny the human factor in the disaster. If there was a forest or a lot more trees, the landslide wouldn’t have extended three kilometers down from where it originated. And from the government side, if it was demarcated as a dormant area, human settlement should have been discouraged, considering the geological peculiarities,” says Soman. He observes that fracture zones were present throughout the estate, down in the valley where the layams were situated too. He moreover points out that when the layams were built, it would not have been listed as a tectonic or fracture zone. “But it has been decades and there was enough time for studies and action. Human responsibility is too high,” he says.  

Also Read:   In devastating landslide in Kerala’s Pettimudi, 18 members of a family die

‘Bodies appeared like they were still asleep’: Eyewitnesses recount Kerala landslide

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Deadly landslides are becoming Kerala’s new reality every monsoon

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• The August 7 landslide at Pettimudi in Kerala’s Idukki district in which 49 plantation workers were buried alive necessitates a micro-level landslide hazard mapping for the state apart from relocation and rehabilitation of people from ecologically fragile danger zones.
• As many as 145 people died in landslides in the last two years in Kerala. The latest tragedy indicates that massive rains and major landslides would continue to be annual affairs. A policy for people living in ecologically fragile areas prone to yearly landslides and floods is needed.
• Quarrying, razing hills for constructions, massive scale road constructions, and expansions in the mountains and mono-crop cultivations are turning contributing factors in the landslides happening because of incessant rains of high magnitude induced by climate change.

P. Mayilswami and his brother Ganeshan, members of an Eco-Development Committee (EDC) in Kerala, had reasons to feel elated in June this year.  The brothers were engaged in the conservation of the endangered Nilgiri tahrs in Eravikulam National Park for three decades. The calving season had just concluded, and the hoofed mammals birthed 155 individuals.

The brothers had studied only up to primary class. Still, they were known for their valuable contributions in the habitat protection and tourism management of the park, according to local forest range officer Job J. Neriyamparambil. The national park is near Munnar, a famous hill station in Kerala’s Idukki district.

As this year’s calving season ended during the COVID-19 lockdown, visitors were absent, and as a result, there were no celebrations. But the brothers insisted with the range officer for a gala event in the post-pandemic phase to celebrate the achievement. 

In the previous calving season (in 2019), the number of new births was  81. As many as 75 calves were born in 2018, and 87 in 2017. Now the total number of tahrs in Eravikulam has risen to 726, an all-time high. 

Mayilswami and Ganeshan were “faces of conservation” in Eravikulam, and they had played a significant role in the sustainable management of the national park, said Neriyamparambil.

But in the early hours of August 7,  2020, a deadly landslide at Pettimudy, a plantation village in the foothills of Rajamala stretch of Eravikulam, buried the brothers and their families under mud and rubble of their line houses, locally called ‘ layams.’

Rescue workers are yet to trace them. A portion of Rajamalai came crashing down on a cluster of line houses of estate workers at Pettimudi. The death toll from the incident is 49 and 22 are still missing. Former estate workers, Ganeshan and Mayilswamy were also residents of the colony comprising 40 line houses, which swept away in the landslide accompanied by torrential rains. 

Only 12 people belonging to two families had escaped the tragedy. Till Sunday evening, 42 bodies were recovered. There is no trace of others who were present in the colony when disaster struck.

According to local gram panchayat member M Shantha, heavy rains had almost isolated the cluster of houses for the last one week, and there was no power supply in the colony for four days. “As a result, mobile phones were not functioning. People living in the upper colony woke up hearing the sound. But nothing could be done as it was pitch dark,” she said.

S Hepsi Christinal, Munnar block programme co-ordinator of Samagra Shiksha Kerala Project, said the lockdown aggravated the tragedy. “The Pettimudi cluster of houses has 18 students in total, and all of them are now missing in the landslide. Had their residential schools elsewhere been active, they might have been safe in the hostels. As schools were not operational, the children had returned to their homes in Pettimudy much before the onset of the southwest monsoon,” Christinal said.

Though estate workers by profession for several generations, all Pettimudi residents are landless Dalits hailing from Theni, Madurai, and Kambam regions of Tamil Nadu. Their families were hit by a financial crunch when the plantation sector landed in crisis. Most of them turned part-time jeep drivers managing tourists arriving at Eravikulam. Some others found rehabilitation with the EDCs.

According to forest department officials, the tea estate that housed the now-buried cluster of ‘ layams ’ formed part of a wildlife corridor. It is barely ten km away from Eravikulam National Park and Anamudi Massif, the highest peak in south India.

Identified as ecologically unstable, Idukki has seen several landslides in the last year. The Gap Road in the Kochi-Dhanushkodi national highway stretch in the High Ranges of Anamalai Hills alone witnessed 20 landslides since March end when summer rains started occurring. However, the Rajamala region has seen very few activities that could disturb the slopes in the recent period, and has not been affected by a landslide in the past, according to knowledgeable sources. 

A spate of landslides point to lack of government policy

In the Gap Road stretch of the highway there have been large-scale  ecological disturbances due to the indifference of state government and the National Highway Authority of India. On August 6, a landslide occurred on the slopes of the road. The rubble that tumbled down had destroyed 23 acres of a tea estate. 

“It’s true that Pettimudi, which forms part of the Kannan Devan Hills Plantation Company, was free from any kind of encroachments, and there was no major change in land-use patterns. But the area is already identified as ecologically fragile, and the situation turned worse with degradations in the nearby localities acting as a contributing factor. Government claims of evolving plans to relocate people from ecologically fragile areas since 2018 soon after that year’s massive floods had also remained on paper,’’ observed P.T. Thomas, a Congress member of Kerala legislative assembly, who hails from Idukki.

As per information available with state authorities, 145 people died in the last two years in landslides like the ones last year in Kavalappara in Malappuram and Puthumala in Wayanad. These indicate the absence of governmental policy for people living in ecologically fragile areas which are prone to annual landslides and floods. 

Kerala started witnessing the phenomenon called soil piping only last year. Most parts of the Western Ghats region in Kerala are now victims of climate change with intensive rains of small duration, weakening the grip of mountain soil. According to P.U. Das, a soil conservation officer based in Wayanad, rainwater seeps into the subsoil during monsoon’s peak to loosen the firm grip between mud and rocks. As water-bearing earth starts tumbling down along with rocks, landslides occur. 

T.V. Sajeev, principal scientist with Kerala Forest Research Institute said quarrying, razing hills for constructions, large-scale road construction, and expansion in the mountains and mono-crop cultivations are turning contributing factors in the landslides because of incessant rains of high magnitude. 

Over thirty percent of Idukki district is prone to landslides as per the landslide hazard profile map of Kerala Disaster Management Authority. The situation is highly critical in Munnar and its surroundings. 

A fter the floods of 2018, the Kerala government had announced the launch of a micro-level landslide hazard mapping for the state apart from relocation and rehabilitation of people from ecologically fragile danger zones. But nothing has happened so far though the floods have become an annual phenomenon since then.  

According to Gopakumar Cholayil, a senior scientific officer with Academy of Climate Change Education and Research of Kerala Agriculture University,  rainfall patterns have changed drastically in the state and surrounding Western Ghats parts of Kodagu and the Nilgiris in the last two years with minimal rains in June and July and intense rainfall in August and September. The intensity of the rains has also increased. In Idukki,  Peerumedu and Devikulam taluks have received 261 mm and 229.4 mm rainfall, respectively on August 7 alone.

Kerala has been facing extreme weather events in the past few years. The massive drought in 2015 was followed by the Okhi cyclone of 2017. Massive floods have occurred in 2018 and 2019, along with landslides. The most literate state in India now looks less aware of the implications of climate change.

According to C.P. Rajendran, geoscientist, and professor at the Jawaharlal Nehru Centre for Advanced Scientific Research in Bengaluru, it’s high time for Kerala to frame clear policies on land management and water utilisation. It also has to evolve long term strategies to address annual floods and landslides which target poor people who are forced to live in ecologically fragile lands. He said that there must be greater attention to avoid change in land utilisation patterns and also avoid initiation of large scale projects with substantial environmental implications.

According to Rajendran, the state requires land-use zoning regulations incorporated with landslide susceptibility data. “Kerala has about 19,000 sq km of hill areas with slopes higher than 10 degrees. These areas are thinly forested and largely disturbed by human activities,’’ he said. He is also of the opinion that a landslide susceptibility map can help the state to understand the kind and magnitude of possible landslides in different areas.

Read more: Kerala landslides – GSI advocates land use and zoning regulations

Landslides a new reality

Hydrogeologist V.R. Haridas said landslips and related phenomena are a new reality for Kerala and the state has to evolve long term strategies to address the threat. 

Haridas, who extensively studied the Kavalappara and Puthumala landslips of last year under a Climate Adaptive Project of National Bank for Agriculture and Rural Development (NABARD), is of the opinion that Kerala’s soil structure has changed drastically. “ It seems the changed soil structure cannot withstand heavy rains. The changes that occurred in the last three years have a common pattern. In the absence of comprehensive and scientific approaches, landslides with large numbers of casualties would turn an annual phenomenon,’’ he said. 

Monocropping might have contributed to the situation in Pettimudi while indiscriminate granite quarrying stands as the major reason in other parts like Wayanad, Pathanamthitta and Malappuram, Haridas said.

Till three years ago, Kerala’s monsoon was confined to two to two-and-a-half months beginning on June 1. But about half of the 3,000 mm of annual rainfall is happening in one or two weeks in August-September. The Pettimudi incident coincides with the first anniversary of the devastating landslide at Puthumala in Wayanad, which claimed 17 lives. On the anniversary occasion, Puthumala and nearby Pachakkad had received over 1,500 mm of rains in six days. Last year’s landslide buried 58 homes and damaged 22 others, including a mosque, a temple, several lines of padis of Harrisons Malayalam estate, a canteen, post office, and a bridge.

“Rains this year are higher in intensity and strong winds are accompanying them. Climate change, along with COVID-19 lockdown, has made survival a difficult task in Kerala. People are struggling,’’ said Cholayil.

According to Haridas, rains in the last week with extremely high intensity have created a situation in Wayanad in which slopes of the hills reach a saturation level. “If rains persist, there would be a real risk of it triggering lateral movement and increasing chances of the overburden to slip,’’ he said.

Mohan C. Varghese, vice-president of Kannan Devan hills Plantation Company, a subsidiary of Tata Global beverages that owns the Pettimudi tea estate, said that immediate scientific studies are required on the sudden landslide that buried the workers’ settlement. “Unlike many other parts of Idukki, our estates lack any kind of deforestation or large scale constructions. For over a century, the company had made no alterations in the land use patterns. We lost many precious lives, and similar such instances must not be repeated. The company is ready to associate with any kind of expert studies,’’ he said.

According to sources in the Kerala Disaster Management Authority,  landslides should not have come as a surprise as a range of Kerala’s districts comprising Wayanad, Idukki, Malappuram, and Kottayam witnessed a significant spurt in rainfall in the seven days between July 30 and August 5. Three low-intensity landslides had occurred close to Nilambur in Malappuram before the Pettimudi incident.

An extremely turbulent Arabian sea has started wreaking havoc in coastal areas like Ponnani and Vizhinjam, Floods have already inundated central Kerala towns of Pala, Eerattupeta, Koottikkal, and Mundakkayam.

In Pathanamthitta, three major rivers – Pampa, Manimala and Achenkoil – have risen beyond the warning level. Pampa Triveni, the entrance to pilgrim centre Sabarimala, which was devastated in the 2018 floods, has also been flooded.

“Frequent tectonic activities combined with changing weather patterns due to global warming are cited as reasons for natural calamities including landslides in the Himalayan region. We have to have scientific studies on tectonic activities in Kerala, especially in the upper ranges of Idukki,’’ said Varghese. 

Banner image : Kerala’s soil structure has changed drastically and it appears the changed soil structure cannot withstand heavy rains. Photo by Special Arrangement.

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Major landslides in Kerala, India, during 2018–2020 period: an analysis using rainfall data and debris flow model

• Recent Landslides
• Published: 20 September 2021
• Volume 18 , pages 3629–3645, ( 2021 )

Cite this article

• Nirmala Jain 1 ,
• Tapas R. Martha 1 ,
• Kirti Khanna 1 ,
• Priyom Roy 1 &
• K. Vinod Kumar 1  

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Rainfall-induced landslides on steep slopes are potential hazards to life and property. The state of Kerala in India is witnessing unprecedented death and damage since last 3 years due to landslides triggered by heavy rainfall. In this paper, we present a cause-impact analysis of landslides that occurred due to the monsoon rainfall in the years 2018, 2019 and 2020. We have created an event-based landslide inventory post-rainfall season for the entire state and then selected six major landslides for detailed analysis. Event-based landslide inventory maps are prepared from Earth observation satellite data such as Resourcesat-2, 2A, Cartosat-2S, WorldView-2, Pleiades-1A and 1B, SPOT-6 and 7 and Sentinel-2 acquired before and after the rainfall events. Then, rainfall data were analysed to find out the role of daily and antecedent rainfalls on landslide trigger. Finally, we have carried out numerical debris flow modeling to characterise landslides and assess the impact. Our results show that landslides are triggered by antecedent rainfall of variable durations and are mostly debris flow type that has followed the channel path. The runout length and lateral spreads are controlled by variable frictional parameters of the slope material. Furthermore, reactivation at the crown region is also noticed in few cases that need to be monitored.

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Acknowledgements

This paper is the outcome of the work carried out under the disaster management support (DMS) program of ISRO. We thank Dr. Raj Kumar, Director, NRSC for support to this work. We thank former Director, NRSC Shri Santanu Chowdhury for his support and guidance to this work. We would like to thank Dr. PVN Rao, Dy. Director, RSAA, for his suggestions during the project review. We would also like to thank the International Charter Space and Major Disasters (ICSMD) and its affiliated organisations for sharing satellite images promptly for the generation of value-added products during post-disaster damage assessment. We thank Dr. N Aparna, Group Director, NDC, NRSC and her team for providing the IRS satellite data. Finally, we would like to thank Dr. Shantanu Bhatwadekar, Director, EDPO, ISRO Hq, Dr. G Srinivasa Rao, Associate Director, EDPO, ISRO Hq and Dr. K H V Durga Rao, Group Head, DMSG, NRSC for their active support to this study. Thanks to Shri Arul Raj, I/c Group Head, Bhuvan and his team for hosting the landslide value-added products in the web portal. We gratefully acknowledge IMD and KSDMA for providing the rainfall data and landslide susceptibility map of Kerala.

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Nirmala Jain, Tapas R. Martha, Kirti Khanna, Priyom Roy & K. Vinod Kumar

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Jain, N., Martha, T.R., Khanna, K. et al. Major landslides in Kerala, India, during 2018–2020 period: an analysis using rainfall data and debris flow model. Landslides 18 , 3629–3645 (2021). https://doi.org/10.1007/s10346-021-01746-x

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Received : 25 March 2021

Accepted : 28 July 2021

Published : 20 September 2021

Issue Date : November 2021

DOI : https://doi.org/10.1007/s10346-021-01746-x

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Silent screams of Wayanad: Why heavy rain triggered a killer landslide

Life in Wayanad had been rooted in agriculture, and past generations had lived close to nature

Wayanad was safe and serene for ages, with its hills and forests. To its east, stood the Nilgiris. To the northeast, the Mysore plateau. On the northwest, the Kodagu hills. On July 30, however, landlocked Wayanad was bobbing in a sea of grief as one of its hills came crashing down. The landslide obliterated several villages and took hundreds of human lives.

People all over Kerala whimpered why―even though they knew why. Life in Wayanad had been rooted in agriculture, and past generations had lived close to nature. They worshipped trees, snakes, birds, animals, ancestors and the five elements. They were simple, unlettered people without bile or guile, who trusted everyone. Legal contracts were unknown until the British arrived and until clever settlers trickled in from beyond the hills.

Life changed slowly as ‘civilisation’ spread. ‘Rational’ men ran down rustic wisdom as superstition. Men of scientific temper scorned the land’s sacred groves and dammed its rivers at the crest of the hills. As age-old beliefs trembled and loosened, so too did the invisible tree roots that bound the rocks deep inside the hills. Meandering streams lost their rhythm and went wayward. Who can strengthen the binding roots and the rustic customs―if only to keep alive the flickering hope of averting recurring landslides?

Wayanad was as right as rain in my childhood. Raindrops fell steadily but gently, not scaring anyone. An occasional torrential rain larded the earth. There was fleeting flooding during the monsoons, but no deluge. When the streams overflowed, we swam in the biting cold water or made rafts out of banana stalks and punted around with a pole. The water drained in a day or two.

The rain never hurt us. Old-timers say there were four types of rain in Wayanad, besides the two monsoons in June and October. The Kumbha rain in February-March and the Mina rain in March-April had their own distinct traits. So did the Karkitaka rain July-August and the Chinga rain August-September. Regular rain kept Wayanad evergreen and watered local culture and lore. And it set the calendar for every human activity. An old-world Malayalam saying in Wayanad was, Thula-pathu kazhinjal, pila-pothilum kidakkam . Translation: After the 10th of the month of Libra, you can sleep even in the hollows of jackfruit trees. The rain was punctual and gentlemanly then. Low pressure and climate change were unfamiliar terms.

Four types of winds, from four different directions, blew across Wayanad. They pushed the plants and trees to flower and fruit, said Cheruvayal Raman, a tribal farmer of Wayanad and preserver of rare rice seeds who received the Padma Shri award. These winds bound Wayanad’s soil and climate together, he said. The easterly winds made the place shiver in the chill of November-December. The evenings were cold even in summer, and local people huddled around fire while attending temple and church festivals. People arriving from other parts would wear woollen sweaters and monkey caps as their bus approached Wayanad. The land was so beautiful with its heavenly mist, so inviting with its fertility. Bewitched, outsiders poured in steadily, and then in torrents. Their assaults on nature first wounded the hills, then human lives.

Wayanad has many stories to tell; fearsome stories of Tipu Sultan’s military run; heroic stories of Pazhassi Raja’s guerrilla tactics against the British; stories of an ineffectual Naxalite spring thunder since the late 1960s; and stories of cruel denial of tribal rights. But the most saddening is the story of its loamy soil, which is now a steady lament. An elegy.

The soil was rich in humus―natural manure that nurtured coffee, cardamom, pepper, paddy and tea. The rains always arrived on time. Rains in February-March made coffee flowers bloom and fattened the beans. They also turned black pepper corns long and luxuriant. Relying on the rains, paddy farmers would sow in June as soon as the southwest monsoon arrived, and harvest in November-December after the northeast monsoon receded. Some of them would sow again, but lightly on dry earth, in February-March. This age-old schedule has undergone haywire, said Echom Gopi, a local farmer and cultural activist. Erratic rains have disrupted Wayanad’s agricultural tenor.

Every house had an attached ala , a thatched shed for the cattle. It was just an extended awning in modest houses. The cattle roamed the fields, their dung nourishing the fields. Rice stalks left to rot in the fields after harvest, along with bundles of green leaves and grass, further enriched the clayey topsoil. Wayanad’s fertility began declining after farmers turned to monoculture and chemical fertilisers. The topsoil has lost its clayey quality.

As a boy, I had to hop across four rivulets to reach an unpaved road in my village, Panamaram, which is now a small town. Wayanad was full of such brooks. People called them kaithod, edathod, aruthod and naduthod , indicating their size; thod means rivulet. Many rivulets vanished when rubber trees invaded our backyards on invitation. Rubber also erased tall trees like ebony and mahogany from villages, just as tea plantations had done on the hill slopes decades before. Lush undergrowth too was lost, along with humble herbs like thumpa, thakara and touch-me-not. Thousands of pits for planting rubber were noticed in the upper parts of Kavalappara, one of the villages that disappeared in the landslide in July.

On the evening before the disaster, flocks of panicky birds pecked at the windows of many houses in Chooralmala and Mundakkai villages. A herd of elephants entered Chooralmala that evening, an unusual occurrence in this village. Perhaps they had intimations of an impending rush of a river of tears. The villagers pounded on tin drums to drive the herd back―and then went to bed, never to wake up again.

Man-animal conflict was uncommon in Wayanad in the last century. Now, wild animals come raiding quite often, while many kinds of birds, butterflies and dragonflies have deserted the villages. So have the fish. There were 40 varieties of fish in the Kabani river in Mananthavadi. The British civil servant William Logan, who wrote the Malabar Manual (1887), gave the Valliyoorkavu river a shimmering name: he called it the fish pagoda.

Jackals and wild hens of our village now play their hunter-prey game elsewhere perhaps. Even our crabs and earthworms have slid away. The eerie calls of the cicada and the cricket, which kept timid little me indoors after dark, can no longer be heard. More than them, I miss the swamps in the rice fields where people made wells in a natural way. A length of palm tree trunk, its bark chiselled out, was sunk vertically into the swamp―and up came unbelievably pure drinking water.

We called these swamps koravakandam . These were like quicksands that in our local legends sucked in humans and animals. Near my home, there was a large and deep pond, now extinct. Thousands of wells, ponds and brooks in Wayanad have become ‘developed’ land.

The word quarry was unknown in my childhood. Now there are countless quarries in the crests of our hills where granite is blasted with dynamite. The road from Vellamunda to Banasura Sagar is heartbreaking with the sight of hills being split, bored and blasted for ripping rocks. One can see these wounds from miles away.

Some decades ago, there were shops and tea plantations only at Adivaram, the place from where vehicles climb up the hills. Now plantations have trekked to the top of the hills, said Azeez Tharuvana, a social worker and professor of Malayalam. “The owners say it is private land. But, for us it was forest.” Tourist resorts stand unchallenged even on the Kuttiady pass to the west of Wayanad. Kuttiady has a hydroelectric power station with several dams in the hills, including Banasura Sagar, but everyone turns a blind eye to the dam water damaging the innards of the hills.

The hills no longer look dark and mysterious at night. Yellowish lights from tourist resorts on hilltops serve as beacons for visitors driving from the passes, and each resort has built kilometres of roads on private land. Unplanned tourism has been robbing Wayanad of its own charms. In caring countries, tourists trek from the valleys to the hills; in Wayanad, tourist resorts have been built on the peaks and their slopes.

Humans and wild animals were once good neighbours in Wayanad. They respected an invisible fence between them. But as encroachers shrank the forest, the animals felt compelled to seek food outside. Teak plantations posed another threat to them by depleting water in the forest. As the watering holes dried, elephants and deer forayed into villages to feast on another recent spectacle―banana plantations. Banana has edged out paddy in many villages. The story of human-animal conflict has many layers to it.

The 14-day Vallioorkav temple festival has been a symbol of solidarity of rivers, forests and tribals. The temple stands on a hill, with the Kabani flowing below, and the place was serene until concrete buildings came up. A building for the weekly market hinders drainage of water during heavy rain. Now hardly anyone remembers the sacred ritual of feeding the fish in the river.

Tribal ways of growing food had changed with the arrival of Jain families from Karnataka centuries ago. The Jains did many a good turn for Wayanad―they built small bunds and canals for irrigation, and mud paths for bullock carts. Wayanad had no tall buildings 50 years ago. My early childhood was spent in a grass-roofed house made of mud. All the neighbouring houses were covered with grass, straw or leaf. While I was in primary school, my father changed our grass roof with thatch, which was considered a major upgrade in those days. Among the hundred houses in my village, only two had concrete roofs. All the houses stood on the edge of rivulets and were several hundred metres apart. Today concrete structures on tiny plots dot the valleys.

The road to Mananthavadi town offered a visual feast for us children. Along one side, there stretched an abyss, breathtaking with green vegetation and silvery streams. Today you will find tall buildings rising from terraces in the abyss and peeping at the tarmac.

Tribals of Wayanad were a resilient lot who had defied deadly malaria. Some of them, like the Kurichya, lived as joint families in sprawling ancestral homes. Most other tribal groups―the Paniya, Adiya, Kuruba and Naika―lived in clusters of thatched little houses. In the name of modernity, the government offered them money to build concrete houses. The uprooting of tribals from their habitat has affected the very culture of Wayanad.

A landslide had destroyed an entire tea estate in Mundakkai in 1984. The survivors of that disaster have fallen victim again―the whole village disappeared in the July landslide. The Puthumala tea estate, which suffered a landslide in 2019, is only 5km from Mundakkai. Why did they rebuild their houses at the very spot where terrible landslides had occurred? How did this area grow into a town?

For visitors, Meppadi is just a tourist centre; for the local residents, it is a trading hub. It is a small town surrounded by tea estates. The tea workers here live in the estate padi (also called layam ), but are ejected from there upon retirement. To get government aid to build a house, one needs to own at least five cents of land. Land in the villages is too expensive for the tea workers to buy, so they buy where they can―on marshes and hilltops. Many victims of the landslide in Mundakkai and Chooralmala had despicable wages.

The communist leader Annie Raja was a candidate in the last Lok Sabha election from Wayanad. She had first visited Wayanad in the 1980s. She remembered a bus ride on a chilly morning from Iritti to Kalpetta to Wayanad: “Dahlia flowers were blooming all the way. Dark-red roses and many other beautiful flowers swayed in every backyard. What a land of flowers it was.”

No flowers waved at her during the election campaign last April. “The dahlias have disappeared,” she said. “The weather has completely changed. Thoughtless tourism and development have done Wayanad in.”

Who can save the land of lost flowers?

The writer is an award-winning Malayalam journalist.

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Why Goa could be the next Wayanad

Goa's landscape — characterised by plateaus and steep slopes — is particularly vulnerable to erosion and landslides if its natural features are disturbed..

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• Goa’s 400-odd villages have played a crucial role in protecting these hills
• For generations, the local communities have regarded the hills as sacred,
• However, this reverence is under threat, as infrastructure projects boom

In the wake of the devastating landslide in Kerala's Wayanad, in July, which claimed hundreds of lives, concerns are rising among environmentalists and residents in Goa.

The fear is that unchecked hill-cutting in the state could lead to similar catastrophic events. Goa, a state known for its unique topography and rich biodiversity in the Western Ghats, is facing rampant destruction of its hills to facilitate commercial and infrastructural developments.

Environmentalists are intensifying their efforts to halt what they describe as "massive hill-cutting," driven by both private and government-led construction projects.

The situation has been exacerbated by recent amendments to the Town and Country Planning (TCP) Act, specifically Section 39A, which grants the chief town planner significant authority to alter regional and development plans.

Critics argue that this change concentrates too much power in a single office, allowing land to be rezoned with minimal oversight. Activists believe that this move is intended to fast-track commercial ventures, bypassing the rigorous scrutiny such projects typically require.

Prabhudessai and other activists emphasise that these developments are short-sighted and could cause irreversible damage to Goa's natural ecosystems. They point out that unchecked construction could lead to a loss of biodiversity, increased pollution, and water shortages. Furthermore, they argue that these decisions are being made without adequate public consultation, sidelining local communities and environmental experts.

"There is no permission for hill-cutting that has been given by my department in the last six months," Rane said, adding that his department has filed 900 complaints about such activities. However, environmentalists remain unconvinced, pointing to ongoing projects like those along National Highway 17B, where hill-cutting continues unabated.

As hill-cutting and construction accelerate, environmentalists fear that Goa is on the brink of an ecological crisis.