case study of landslide in india

• Brief Report
• Open access
• 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

6709 Accesses

13 Citations

1 Altmetric

Metrics details

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.

Achu AL, Joseph S, Aju CD, Mathai J (2021) Preliminary analysis of a catastrophic landslide event at Pettimudi, Kerala state. India Landslides 18:1459–1463

Article   Google Scholar  

Alcántara-Ayala I, Esteban-Chávez O, Parrot JF (2006) Landsliding related to land-cover change: a diachronic analysis of hillslope instability distribution in the Sierra Norte, Puebla, Mexico. CATENA 65:152–165

Batar AK, Shibata H, Watanabe T (2021) A novel approach for forest fragmentation susceptibility mapping and assessment: a case study from the Indian Himalayan region. Remote Sens 13(20):4090

Escobar-Wolf RV, Sanders JD, Oommen T, Sajinkumar KS, Vishnu CL (2021) A GIS tool for infinite slope stability analysis (GIS-TISSA). Geosci Front 12(2):756–768

Getachew N, Meten M (2021) Weights of evidence modeling for landslide susceptibility mapping of Kabi-Gebro locality, Gundomeskel area central Ethiopia. Geoenviron Disasters 8(1):1–22

Hao L, Rajaneesh A, van Westen C, Sajinkumar KS, Martha TR, Jaiswal P, McAdoo BG (2020) Constructing a complete landslide inventory dataset for the 2018 Monsoon disaster in Kerala, India, for land use change analysis. Earth Syst Sci Data 12(4):2899–2918

Hao L, van Westen C, Rajaneesh A, Sajinkumar KS, Martha TR, Jaiswal P (2022) Evaluating the relation between land use changes and the 2018 landslide disaster in Kerala, India, for land use change analysis. CATENA 216:106363

Istiyanti ML, Goto S, Ochiai H (2021) Characteristics of tuff breccia-andesite in diverse mechanisms of landslides in Oita Prefecture, Kyushu Japan. Geoenviron Disasters 8(1):1–14

Lahai YA, Anderson KF, Jalloh Y, Rogers I, Kamara M (2021) A comparative geological, tectonic and geomorphological assessment of the Charlotte, Regent and Madina landslides, Western area Sierra Leone. Geoenviron Disasters 8(1):1–17

Lan H, Wang D, He S, Fang Y, Chen W, Zhao P, Qi Y (2020) Experimental study on the effects of tree planting on slope stability. Landslides 17:1021–1035

Puente-Sotomayor F, Mustafa A, Teller J (2021) Landslide susceptibility mapping of urban areas: logistic regression and sensitivity analysis applied to quito Ecuador. Geoenviron Disasters 8(1):1–26

Ramachandra T, Kumar U (2011) Characterisation of landscape with forest fragmentation dynamics. J Geogr Inf Syst 3(3):242–253

Google Scholar  

Reichenbach P, Busca C, Mondini AC, Rossi M (2014) The influence of land use change on landslide susceptibility zonation: the Briga catchment test site (Messina, Italy). Environ Manage 54:1372–1384

Article   CAS   Google Scholar  

Sajinkumar KS, Anbazhagan S (2015) Geomorphic appraisal of landslides on the windward slope of Western Ghats, southern India. Nat Hazards 75(1):953–973

Sajinkumar KS, Oommen T (2020) Rajamala landslide: continuation of a never-ending landslides series. J Geol Soc India 6:310

Sajinkumar KS, Arya A, Rajaneesh A, Oommen T, Ali P, Yunus RVR, Avatar R, Thrivikramji KP (2022) Migrating rivers, consequent paleochannels: the unlikely partners and hotspots of flooding. Sci Total Environ 807:150842

Sajinkumar KS, Oommen T (2021) Landslide atlas of Kerala. Geol Soc India, p 34.

Vishnu CL, Sajinkumar KS, Oommen T, Coffman RA, Thrivikramji K, Rani VR, Keerthy S (2019) Satellite-based assessment of the August 2018 flood in parts of Kerala, India. Geomat Nat Hazards Risk 10(1):758–767

Vishnu CL, Rani VR, Sajinkumar KS, Oommen T, Bonali FL, Pareeth S, Thrivikramji K, McAdoo BG, Anilkumar Y (2020) Catastrophic flood of August 2018, Kerala, India: partitioning role of geologic factors in modulating flood level using remote sensing data. Remote Sens Appl Soc Environ 2:100426

Wadhawan SK, Singh B, Ramesh MV (2020) Causative factors of landslides 2019: case study in Malappuram and Wayanad districts of Kerala. India Landslides 17:2689–2697

Weidner L, Oommen T, Escobar-Wolf RV, Sajinkumar KS, Rinu S (2018) Regional scale back-analysis using TRIGRS: An approach to advance landslide hazard modeling and prediction in sparse data regions. Landslides 15(12):2343–2356

Yunus AP, Fan X, Subramanian SS, Jie D, Xu Q (2021) Unraveling the drivers of intensified landslide regimes in Western Ghats, India. Sci Total Environ 770:145357

Download references

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.

Author information

Authors and affiliations.

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

You can also search for this author in PubMed   Google Scholar

Contributions

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

Corresponding author

Correspondence to K. S. Sajinkumar .

Ethics declarations

Ethical approval.

The data employed in this work is accessible to the public upon request and therefore ethical approval is not required. This paper is not being submitted to any other journal at the same time.

Competing interests

The authors declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work, there is no professional or other personal interest of any nature or kind in any product, service, and/or company that could be construed as influencing the position presented in, or the review.

Additional information

Publisher's note.

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/ .

Reprints and permissions

About this article

Cite this article.

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

Download citation

Received : 13 February 2022

Accepted : 02 July 2022

Published : 13 July 2022

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

Share this article

Anyone you share the following link with will be able to read this content:

Sorry, a shareable link is not currently available for this article.

Provided by the Springer Nature SharedIt content-sharing initiative

• Human interventions
• Western Ghats

• Share full article

Advertisement

Landslide in India Buries Dozens, Killing at Least 25

Days of heavy rain had loosened the soil. India and neighboring Bangladesh have had record rainfall and severe flooding in the past two months.

By Karan Deep Singh

• Published July 1, 2022 Updated July 2, 2022

At least 25 people were killed and more feared dead, after days of heavy rainfall set off a landslide in India’s remote and mountainous northeastern state of Manipur.

It is the latest tragedy in a country that has been plagued by catastrophic rainfall and flooding in recent months. The extreme weather has destroyed communities, forced evacuations and threatened lives.

On Saturday, rescue workers in Manipur were still looking for dozens of people, who were instantly buried under layers of mud and rocks overnight Wednesday, when the landslide occurred in the Noney District. Indian television stations showed rescue personnel carrying mud-covered bodies on stretchers.

More rainfall has made rescue efforts even more challenging, Nongthombam Biren Singh, the chief minister of Manipur State, said on Twitter . He said 25 bodies had been recovered and 18 injured people had been rescued. “38 persons are still missing,” he added.

Many of the people who died and those still trapped under the rubble had been in the area to work on the construction of a railroad station deep in the mountains. Some were soldiers in the Indian Army. Others were railway workers, local villagers and laborers.

“The entire country is deeply saddened by loss of lives,” Mr. Singh said on Friday.

Prime Minister Narendra Modi said on Twitter that he had reviewed the situation in Manipur and had assured Mr. Singh of “all possible support” from the central government. “I pray for the safety of all those affected,” he said. “My thoughts are with the bereaved families.”

Weeks of heavy rainfall from the monsoons have already killed more than 100 people and left millions homeless in India’s northeast and in neighboring Bangladesh. More than 60 people were killed in May during days of flooding, landslides and thunderstorms that left many people without food and drinking water and isolated them by cutting off the internet.

Tying climate change to an extreme weather event requires extensive scientific analysis. But climate change is often a contributing factor.

Scientists have said that India and Bangladesh are particularly vulnerable to climate change because of their proximity to the warm tropical waters of the Indian Ocean and the Bay of Bengal, which are increasingly experiencing heat waves . The rising sea temperatures have led to dry conditions in some parts of the Indian subcontinent and a significant increase in rainfall in other areas, according to a study published in January by the Indian Institute of Tropical Meteorology in Pune.

In India’s northeastern state of Assam, one of the worst affected areas during the pre-monsoon and monsoon season, a paramilitary camp was inundated by floodwaters on Friday after persistent rain over the last three days.

Mr. Singh, the chief minister, said the authorities were expecting bad weather to persist in Manipur. “The situation in the landslide affected area,” he said, “is still serious.”

The India Meteorological Department forecast heavy rainfall on Sunday in at least 14 states, including Assam, Manipur, Meghalaya, Tripura and Nagaland, all in the northeast. The heavy rains delayed flights and submerged roads in India’s capital, New Delhi, on Thursday.

Karan Deep Singh is a reporter and visual journalist based in New Delhi, India. He previously worked for The Wall Street Journal, where he was part of a team that was named a finalist for the 2020 Pulitzer Prize in Investigative Reporting and nominated for a national Emmy Award. More about Karan Deep Singh

Science News by AGU

The 14 August 2023 landslides in Himachal Pradesh, India

Share this:.

• Click to print (Opens in new window)
• Click to email a link to a friend (Opens in new window)
• Click to share on Twitter (Opens in new window)
• Click to share on Facebook (Opens in new window)
• Click to share on LinkedIn (Opens in new window)

The Landslide Blog is written by Dave Petley, who is widely recognized as a world leader in the study and management of landslides.

On 14 August 2023 extremely heavy rainfall affected the north Indian state of Himachal Pradesh, bringing widespread destruction. To date it is known that at least 58 people have been killed in flooding and landslides , but this may well increase further.

The most serious event appears to have occurred in the Shiva Temple in the Summer Hill area of Shimla in Himachal Pradesh, where a landslide struck a complex that was packed with worshipers. At least 10 people were killed, but up to 20 more may be buried in the debris. Rescue operations have been severely hampered by further rainfall. A further five people were killed nearby at Fagli.

Journalist Naveen S Garewal tweeted this image of the aftermath :-

Nine people have lost their lives, and more are trapped inside Shiv Mandir in Shimla’s Summer Hill after the temple structure collapsed due to heavy rainfall #Shimla #shivmandir #rainfall #Himachal #HimachalFloods #HimachalPradeshRains pic.twitter.com/Fa4jXeGKJ7 — Naveen S Garewal (@naveengarewal) August 14, 2023

Meanwhile, a further landslide destroyed a substantial section of the Shimla-Kalka railway line, a UNESCO world heritage line, near to Summer Hill. Freelance journalist Saurabh Chauhan tweeted some images of the aftermath :-

The track has been damaged in a number of other locations.

In Solan district, also in Himachal Pradesh, there are reports of a landslide that killed seven members of a single family in Jadon in Kandaghat subdivision. At least four other people were killed in the district, including two children at Balera and a woman at Banal in Ramsheher tehsil.

There are also reports of a single fatality in a landslide in the Rangas area of Hamirpur, whilst in Seghli in Mandi district, seven people were killed in a landslide. It is likely that there were other fatalities in landslides across Himachal Pradesh.

Meanwhile, the same rainfall has also caused substantial issues in the western part of Nepal. Obtaining good information from this area is very challenging, but there are reports of an intriguing landslide on the Kali Gandaki river. ICIMOD has tweeted about a valley blocking landslide , and subsequent flood, which appears to have caused substantial damage. There are also videos of the subsequent flood :-

The village of Kagbeni in Mustang was substantially damaged, but the location of the landslide is unclear.

The most intense part of the monsoon in South Asia continues to affect the western part of the Himalayas, such as Himachal Pradesh and Uttarakhand, with much less rainfall in the east. Indeed, some parts of north India are currently suffering a substantial rainfall deficit .

The eastern Himalayas typically get lower monsoon rainfall than the west. Landslides are typically triggered by large variations from the normal level of rainfall for that location, rather than absolute rainfall totals (in other words, 100 mm in 24 hours would trigger extensive landslides in the UK but would be unlikely to trigger any in Taiwan), explaining why these rainfall events are causing so many problems.

But of course underpinning all of this is the impact of poor quality development, such in inadequately engineered roads, which has made the landscape so much more vulnerable.

Text © 2023. The authors.  CC BY-NC-ND 3.0 Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Features from agu publications, tiny satellites can provide significant information about space, a powerful new model for u.s. climate–air quality interactions, reflecting on 5 years at the helm of jgr: planets.

• 68th BPSC Essay Classes & Tests
• 68th BPSC Mains Test Series

Current Affairs Specials

• Current Affairs

A Detailed study on Landslides in India

• Posted By 10Pointer
• Categories Geography
• Published 21st Aug, 2021

Introduction

Landslides have caused massive damage of life and property during extremely heavy rain across India. The Kedarnath landslide in Uttarakhand in June 2013, caused by flash floods that resulted in over 5,000 deaths, was identified as the most tragic such disaster. Recently a landslide hit Kinnaur district in Himachal Pradesh, which happened for the second time in 15 days, killing at least 14 people and burying many others. The tragedy was exacerbated by heavy rain, hailstones, and debris on vehicles, including a state-of-the-art transport bus on National Highway 5.

                                                                           15% of India's landmass is prone to landslides, however, its vulnerability will increase in the future due to climate change and human pressure. This improved size can be considered by adopting a multidisciplinary approach that integrates all aspects of disaster risk management namely mitigation, preparedness, response, and rehabilitation.

What is landslide?

Landslides are the rapid movement of rock, soil, and vegetation under a slope under the influence of gravity. It can be caused by natural factors, e.g. Heavy rain, earthquakes, or can be caused by extreme human disturbance of the slope - stability. Landslides are rarely at the same level as earthquakes or volcanic events. The magnitude and magnitude of landslides, however, depends on the geological structure, the slope angle of the slope, the nature of the mountain rocks, and the interaction of people with the slope. As per Geological Survey of India, the window of economic loss due to landslides may reach between 1-2% of the gross national product in many developing countries.

Causes of Landslides

The main causes of landslides are

• Rain and snow
• Excessive or continuous rainfall can lead to massive landslides in the high slopes where National Highways and roads are built.
• The Nashri region between BatoteRamban-Ramsu, and Banihal (Jammu and Kashmir) is prone to landslides. Landslides in this area are especially difficult during the rainy season and winter when car traffic is disrupted for a few days.
• Earthquakes and volcanic eruptions
• Earthquakes are a major cause of landslides in mountainous areas. In India, Landslides are more common in the rolling hills of the Tertiary Period, such as the Himalayas.
• In the Kashmir region, the 1905 earthquake caused a landslide in the small Himalayas and the Greater Himalayas in which several thousand people lost their lives.
• Volcanoes also cause landslides in mountainous areas.
• Mining, Mining and Cutting Road
• The continued extraction of coal, minerals, and minerals from the mines and quarries and the construction of roads by cutting slopes on the rolling hills create the ideal conditions for the availability of soil extraction.
• Such landslides can be seen throughout the Himalayas and in the Eastern and Western Ghats.
• Loading about housing
• The unplanned growth of cities and towns in hilly areas without exploring soil and rock is also an important cause of landslides.
• The eastern slope of Nanital (Uttarakhand) is sinking due to the heavy load of hotels and residential buildings.
• Deforestation
• Deforestation and other human activities also cause landslides. Most landslides are minor involving some blocks up to a few meters across. But some are big enough to cause disaster. They can bury roads, buildings, and other structures.
• The negative effects of erosion can be reduced by observing deforestation on mountain slopes, by following the building codes of these areas, and by avoiding the construction of buildings on steep slopes.

India among the countries most affected by landslides due to human activities:

• Earthquakes caused by human activities are increasing worldwide and India is among the worst-affected countries, accounting for at least 28% of such incidents over the past 12 years, according to a published study.
• Investigators have collected data on more than 4,800 deadly earthquakes that occurred from 2004 to 2016, leaving behind those caused by earthquakes.
• More than 56,000 people have been killed by landslides worldwide during this time, most of them affected by one slope, according to a study based on the Global Fatal Landslide Database (GFLD).
• At least 700 of these deadly landslides were caused by construction work, illegal mining, and uncontrolled rolling of hills.
• While the trend is global, Asia has been found to be the most affected continent where 75% of landslides occurred, with the highest number reported near the Himalayan Arc.
• All 10 countries in the world of deadly humanitarian catastrophes are located in Asia. India accounts for 20% of these cases.
• The study states that fatal soil erosion is on the rise in India, where landslides caused by construction occur during this period, followed by China (9%), Pakistan (6%), the Philippines (5%), Nepal (5%) and Malaysia (5%).).
• We knew that people were putting increasing pressure on the local community, but it was surprising to find the obvious trend in the database that deadly landslides caused by construction, illegal mountain cutting and illegal mines were increasing worldwide during this time.

Vulnerability profile of India

In India, the hazard affects at least 15% of the world's land area (approximately 0.49 million square km.) It is most common in geodynamical operating areas in the Himalayan and Arakan-Yoma areas in the north-eastern part of the country and as in the more stable areas of Meghalaya Plateau, Western Ghats and Nilgiri Hills. The Nilgiri Mountains, located at the confluence of the Eastern and Western Ghats, bear countless scars from landslides.

Consequences of landslides

• Loss of Life: The most devastating effect of landslides is the loss of precious human and animal life. In the latest Kinnaur Landslide, 14 deaths have already been reported.
• Restrictions on Travel: Mud, rocks, and sloping debris create a barrier to critical transport routes such as highways, railways, etc. This prevents the movement of goods and people.
• Infrastructure Damage: Several houses, buildings, roads, and other infrastructure are damaged whenever an earthquake occurs.
• Economic Loss: The amount of money spent restores lost infrastructure, mass rehabilitation, and the provision of relief services to affected people.
• Risk of Water Availability: When soil erosion occurs on slopes of a river valley, the size of the sliding can reach the bottom of the valley and cause partial or complete closure of the river channel. This pile of debris leading to the river closure is often called the Landslide dam. It can affect the availability of water to nearby people.

Measures taken for land management in India

• National Disaster Risk Management Strategy (2019): Addresses all aspects of disaster risk reduction and management, including risk mapping, monitoring and early warning systems, awareness programs, skills development, training, regulations and policies, stabilization and landslide reduction, etc.
• Hazard zones have to be identified and specific slides to be stabilized and managed in addition to monitoring and early warning systems to be placed at selected sites.
• Hazard mapping should be done to locate areas commonly prone to landslides. It is always advisable to adopt area-specific measures to deal with landslides.
• Restriction on the construction and other developmental activities such as roads and dams, limiting agriculture to valleys and areas with a moderate slope, and control on the development of large settlements in high vulnerability zones, should be enforced.
• Landslide Hazard, vulnerability and Risk Assessment
• Multi – Hazard Conceptualisation
• Landslide Remediation practice
• Research and Development, monitoring, and early warning
• Knowledge network and management
• Capacity building and Training
• Public awareness and Education
• Emergency preparedness and response
• Regulation and Enforcement

Suggestive Measures

• Firstly, provinces such as Himachal Pradesh and Uttarakhand in high-risk areas should be especially vigilant in pursuing disruptive projects. There should be a proper implementation of the environmental impact assessment procedures prior to the start of mining or dam construction.
• Second, there should be the adoption of small-scale zoning processes for mountains and other high-risk regions.
• Third, more funding should be made to planning and demolition agencies and reducing structures to improve disaster management.
• Fourthly, there should be the involvement of trained staff in the area to strengthen the reduction of public awareness programs and programs.
• Fifth, mitigation strategies such as limiting agriculture in the valleys and areas with moderate slopes, promoting large-scale deforestation programs, and building masses to reduce water flow, etc.

The conclusion

• Increased human encroachment on the environment has led to an increase in the number of natural disasters.
• However, the National Disaster Response Force under The Disaster Management Act, 2005 has carried out many rescue operations by providing assistance and assistance to the affected country, including deployment, at the request of Government, Armed Forces, Central Military, and similar communications, air and other supplies. They have also worked to increase public awareness to reduce the impact of these natural disasters by organizing preparedness campaigns.

Related Articles

State of Prisons in India

A detailed account on Abortion Rights in India

Difference between Arctic and Antarctica Regions and effects of Climate change

Tribal Revolts in India during its Freedom struggle

Status of Economy since Pandemic

Horticulture in India: Growth and its Future

Tribal communities in India: Their Culture and significance

Buddhism in India: From Rise to its Decline

Corruption in India: An Analysis

Economic Liberalization in India

ASHA worker’s vision for India@100

Voting Rights to NRIs

DRDO carries out maiden test of Phase-II of ballistic missile defence

One nation, one ITR form

Pahari community in ST list of Jammu and Kashmir

How does tokenization prevent online card fraud?

Languages panel recommendations on Inclusion of Hindi as the Official language

Palaeogenomics: Explaining our Origins

China’s 73rd year of Independence: India- China relations

Expanding India’s geospatial technology

Verifying, please be patient.

Subscribe our Channels

Even slightly believable. If you are going use a passage of Lorem Ipsum need some

Useful Link

• Privacy & Policy

Contact Info

8/3, 2nd Floor, Abdul Aziz Road, Near OBC Bank, Karol Bagh, New Delhi, Delhi 110005

[email protected]

© 2024 10Pointer. All Rights Reserved

Not registered yet?

  register here!

create new account

Already have an account? LOGIN!

Forgot Your Password?

Please enter your email address below. You will receive a temporary password.

Call us @ 08069405205

Search Here

• An Introduction to the CSE Exam
• Personality Test
• Annual Calendar by UPSC-2024
• Common Myths about the Exam
• About Insights IAS
• Our Mission, Vision & Values
• Director's Desk
• Meet Our Team
• Our Branches
• Careers at Insights IAS
• Daily Current Affairs+PIB Summary
• Insights into Editorials
• Insta Revision Modules for Prelims
• Current Affairs Quiz
• Static Quiz
• Current Affairs RTM
• Insta-DART(CSAT)
• Insta 75 Days Revision Tests for Prelims 2024
• Secure (Mains Answer writing)
• Secure Synopsis
• Ethics Case Studies
• Insta Ethics
• Weekly Essay Challenge
• Insta Revision Modules-Mains
• Insta 75 Days Revision Tests for Mains
• Secure (Archive)
• Anthropology
• Law Optional
• Kannada Literature
• Public Administration
• English Literature
• Medical Science
• Mathematics
• Commerce & Accountancy
• Monthly Magazine: CURRENT AFFAIRS 30
• Content for Mains Enrichment (CME)
• InstaMaps: Important Places in News
• Weekly CA Magazine
• The PRIME Magazine
• Insta Revision Modules-Prelims
• Insta-DART(CSAT) Quiz
• Insta 75 days Revision Tests for Prelims 2022
• Insights SECURE(Mains Answer Writing)
• Interview Transcripts
• Previous Years' Question Papers-Prelims
• Answer Keys for Prelims PYQs
• Solve Prelims PYQs
• Previous Years' Question Papers-Mains
• UPSC CSE Syllabus
• Toppers from Insights IAS
• Testimonials
• Felicitation
• UPSC Results
• Indian Heritage & Culture
• Ancient Indian History
• Medieval Indian History
• Modern Indian History
• World History
• World Geography
• Indian Geography
• Indian Society
• Social Justice
• International Relations
• Agriculture
• Environment & Ecology
• Disaster Management
• Science & Technology
• Security Issues
• Ethics, Integrity and Aptitude

• Indian Heritage & Culture
• Enivornment & Ecology

India’s first high-resolution landslide susceptibility map

Gs paper  1.

  Syllabus: Geography/ Disaster Management

  Context : IIT Delhi’s HydroSense Lab has created India’s first high-resolution landslide susceptibility map .

What is Landslide Susceptibility Mapping?

Landslide Susceptibility Mapping involves creating maps that depict areas prone to landslides based on certain factors. For example, using data on past landslide events and factors like slope steepness , soil type, and vegetation cover, a computer model can analyse these variables to predict areas at high risk.

Features of National Landslide Susceptibility Map:

About Landslide:

A landslide is “ a movement of a mass of rock, earth or debris down a slope”.

Types of flows

• Debris flows : It is a form of rapid mass movement in which a combination of loose soil, rock, organic matter, and slurry that flows downslope. They are commonly caused by intense precipitation or rapid snowmelt.
• Earth flow : It is a down-slope viscous flow of fine-grained material saturated with water.
• Mudflow: A mudflow is a wet or viscous fluid mass of fine and coarse-grained material that flows rapidly along drainage channels.
• Creep: Creep is the  slow, steady, downward movement of material  under gravity that occurs in a large area

India’s Vulnerability to Landslides (as per ISRO’s Landslide Atlas of India)

• Global Ranking: India ranks among the top five countries globally prone to landslides, witnessing at least one death per 100 sq km annually due to such events.
• Primary Cause: Rainfall variability, particularly in the Himalayas and Western Ghats, s tands as the predominant cause of landslides in India.
• Geographical Vulnerability: Excluding snow-covered areas, over 12% of the country’s geographical land area is susceptible to landslides.
• Rudraprayag and Tehri Garhwal districts of Uttarakhand have the  highest landslide density and landslide risk exposure in the country.
• About 19% are reported in the North-eastern Himalayas .
• The Western Ghats contribute to over 14% of landslide events .
• Impact in the Western Ghats: Despite fewer occurrences, landslides in the Western Ghats pose significant risks, especially in Kerala , making inhabitants vulnerable to fatalities.

Causes of Landslides:

Effects of landslides:

• In the state of Uttarakhand, India, the 2013 Kedarnath disaster resulted in approximately 6000 deaths.
• The 2014 landslide in Oso, Washington , resulted in significant damage to the Stillaguamish River ecosystem.
• In February 2021, the Chamoli disaster led to the blockage of the Rishi Ganga River and the destruction of various infrastructure in the region.
• Property Damage : The cost of repairing or rebuilding homes, infrastructure, and farmlands can be substantial.
• Displacement : The United Nations Office for Disaster Risk Reduction ( UNDRR ) reports that landslides triggered by heavy rainfall in Nepal in 2020 displaced more than 9,000 households , leaving many families without shelter.

Recent examples of landslide disasters in the past year:

• Joshimath Sinking in Uttarakhand
• June 2023: A landslide in the Noney district of Manipur , India, killed at least 58 people.
• May 2023: A landslide in Rio de Janeiro , Brazil , killed at least 232 people.
• March 2023: A landslide in Putumayo, Colombia , killed at least 323 people.

Government Measures for Landslide Impact Mitigation:

• Map the 0.42 million sq. km landslide-prone areas across India at a Macro Scale (1:50,000)
• Create a dynamic National Landslide Susceptibility Geodatabase for India
• Establish a nationwide repository on GIS-based Landslide Inventory
• The goal is to enhance understanding, assessment, and management of landslide-prone regions in the country through comprehensive mapping and geospatial analysis.
• National Remote Sensing Centre (NRSC) under the Indian Space Research Organisation (ISRO) has released the Landslide Atlas of India , a detailed guide identifying Landslide Hotspots in the country.

NDMA Guidelines:

National Disaster Management Guideline on Management of Landslides and Snow Avalanches

• Hazard, Vulnerability & Risk Assessment : Identify areas prone to landslide hazards and assess resources at risk
• Early Warning Systems : Continuous monitoring of movements, stress development, and timely data transmission
• Investigations for Risk Assessment : Multi-disciplinary investigations for comprehensive risk assessment leading to the formulation of standards to effectively mitigate the impact of landslides

Way Forward for Landslide Management in India:

Conclusion :

Understanding the causes and effects of landslides is essential for disaster preparedness and mitigation efforts. Implementing early warning systems, land-use planning, and sustainable land management practices can help reduce the vulnerability of communities to landslide hazards. Moreover, international cooperation and sharing of knowledge and best practices are crucial in addressing the challenges posed.

Insta Links:

Landslide Atlas of India

Mains Link:

Disaster preparedness is the first step in any disaster management process. Explain how hazard zonation mapping will help disaster mitigation in the case of landslides UPSC 2019

Differentiate the causes of landslides in the Himalayan region and Western Ghats (UPSC 2021)

• Our Mission, Vision & Values
• Director’s Desk
• Commerce & Accountancy
• Previous Years’ Question Papers-Prelims
• Previous Years’ Question Papers-Mains
• Environment & Ecology
• Science & Technology

‘We can’t defeat nature but we can be climate-resilient’: how plant roots can help stop landslides

Thanks to soil bioengineering in a village in north India, a submerged road was accessible in less than one week, according to officials

O n 14 August 2023, heavy rainfall in north India triggered flash floods and landslides, devastating the region. Kishori Lal, the sarpanch (head) of the Kothi Gehri village in the Himalayan state of Himachal Pradesh, recalls the events of that day: “Our link road connecting to the state highway and a few homes along that road were completely devastated.”

Torrential downpours in nearby Rewalsar, a picturesque lake town popular with tourists, led to several water bodies bursting their banks. The subsequent flooding and landslides wrecked homes in Lal’s village, necessitating the evacuation of hamlets and severing vital links to the outside world. With roads submerged, the ensuing closure of the Mandi-Rewalsar-Kalkhar Road and link roads left scores of tourists stranded and local communities isolated . Amid this chaos, the resilience of Nog, a village in Bilaspur district, stands out. While roads across the region, including those in and around Kothi Gehri, remained closed, the road leading to Nog was accessible in less than one week, according to officials.

The reason lies in an innovative approach: soil bioengineering. Concrete retaining walls 10ft high are the traditional go-to solution used to protect roads from hillside slopes. However, these structures leave exposed slopes vulnerable to erosion during intense rains, exacerbating the risk of landslides.

Sanjeev Dogra, vice-president of the Nog panchayat , the local governing body, describes the threat landslides used to pose: “Our road used to suffer landslides every monsoon, which threatened villagers living nearby,” he says. Before the implementation of bioengineering measures, Nog’s road endured month-long closures on average during every monsoon season.

The turning point came in 2010, when bioengineering techniques were used to stabilise exposed slopes at two locations on the new link road to Nog, as part of the Pradhan Mantri Gram Sadak Yojana (PMGSY), the Prime Minister’s Village Roads Scheme. Launched in 2000, the flagship government programme seeks to provide reliable all-weather connectivity to unconnected rural communities across the country.

“We treated the exposed surface of the potential landslide area near Nog by covering it with wire-mesh netting, planted shrubs and grasses within the grid,” says Pawan Kumar Sharma, director of projects at Himachal Pradesh Road and Infrastructure Development Corporation Ltd (HPRIDCL). “Where landslides were triggered by erosion from a local river, we planted brush hedges and hardwood cuttings to bind the soil.”

The green infrastructure took root within a single season, gradually fortifying the slopes, which were better able to withstand the effects of last year’s deluge.

Neha Vyas, a senior environmental specialist with the World Bank, defines bioengineering as a subset of green infrastructure. This ecological engineering technique involves the strategic planting of vegetation and the incorporation of other organic materials to stabilise soil and enhance ecosystem resilience.

By harnessing the natural properties of plants and their root systems, soil bioengineering can be a sustainable and cost-effective approach to mitigate environmental hazards and promote landscape restoration, which is particularly good in fragile ecosystems.

In Himachal Pradesh, soil bioengineering has “involved the use of vegetation, both living and dead plants, such as bamboo, in conjunction with simple civil engineering structural elements such as catch drains, gabion walls and others,” says Vyas.

The Nog bioengineering initiative was the first of more than 250 mountainous road stretches treated with the World Bank’s assistance. Dalip Chauhan, president of the Jubbal panchayat , attests to its efficacy, citing reduced damage along the state highway #10 during last August’s catastrophic floods.

“If soil bioengineering is designed after due investigation and analysis, and monitored during execution, it effectively controls erosion along roadways, which is crucial to maintain the integrity of the road section and can even help during the heavy rains that are becoming more commonplace due to climate change,” says Vyas.

“Soil bioengineering can also improve the stability of slopes along roads, thereby reducing the risk of landslides, increasing safety for people and protecting assets,” she adds. “By absorbing much more water, bioengineered slopes can reduce the runoff and the ensuing erosion, water logging and damage.”

Beyond that, she believes choosing the right vegetation species could lead to carbon dioxide absorption, habitat creation for wildlife, increased ecosystem resilience and additional livelihood sources for local communities.

after newsletter promotion

Harvesting grass planted by the roadside has saved Sonali, a 38-year-old cattle-rearing resident of Nog, many visits to the forest where the species is usually found. “Planting vegetation that can be used as fodder by the road to help protect it is doubly useful for us,” she tells Dialogue Earth. “I source about half of the fodder I need from the roadside. I wish such species were planted alongside all the roads in the area.”

Soil bioengineering can be a useful tool in combatting erosion and stabilising slopes, but the planning and maintenance is critical.

Even though they understand the need for robust vegetation growth, contractors sometimes prioritise cost over effectiveness. To maximise efficacy, experts advise a multi-pronged approach that ensures vegetation growth, with Vyas pointing out that “horticultural principles must be used along with the application of engineering design principles to build structures that will protect the plant communities as they grow to maturity and function as they would in their natural settings.”

Himachal Pradesh considers it good practice to also appoint supervisors to watch over and maintain sites, and Sharma highlights the importance of selecting low-maintenance indigenous plants “with aesthetic value, medicinal value, commercial value and grasses that can be used as forage for cattle.”

Vyas describes investments in bioengineering as “investments in safety and sustainability, which are much more cost-effective and visually more appealing than hardcore engineering and less environment-friendly structures”.

As Himachal Pradesh prepares for future climatic uncertainties, soil bioengineering emerges as a potential innovative lifeline to help protect lives and livelihoods. “While it is impossible to defeat nature, surely we can use bioengineering and allied techniques to make roads that are as climate-resilient as possible,” says Sharma.

This article was originally published on Dialogue Earth under the Creative Commons BY NC ND licence.

• The alternatives
• Extreme weather

Most viewed

Investigation of rainfall-induced landslide on unsaturated lateritic residual soil slope in Nilgiris, Western Ghats, India using deterministic and reliability analysis

• Published: 11 May 2024
• Volume 83 , article number  221 , ( 2024 )

Cite this article

• Bhavithra Soundararajan 1 ,
• Senthilkumar Vadivel   ORCID: orcid.org/0000-0002-5907-7569 1 &
• Chandrasekaran Sembulichampalayam Sennimalai 2  

13 Accesses

Explore all metrics

The study investigates an earth slide type rain-induced landslide that occurred at Madithorai, Nilgiris District, India in 2009. It consists of detailed field investigations such as topographical survey and borehole investigation, laboratory and numerical investigations. Based on the topographical survey the slope was modelled in SEEP/W programme to perform the uncoupled transient seepage analysis. The cumulative rainfall of 586 mm was given as an input for a duration of 5 days that caused landslide at Madithorai. The results of transient seepage analysis were used to determine the stability of the slope based on the infinite slope method for unsaturated soil. Based on the analysis the failure mechanism of Madithorai landslide was observed. The influence of antecedent rainfall using three different idealized 5-day antecedent rainfall was studied. A threshold intensity was established from the different 5 days antecedent rainfall and the corresponding factor of safety which can be used as for landslide early warning. The factor of safety from deterministic analysis was greater than one which does not imply that the slope is stable. Therefore, the performance of the slope was studied based on the reliability index and probability of failure using the Monte Carlo simulation. The results highlight that the slope is in hazardous condition with a reliability index of 1.15 and the probability of failure of 11.7%. Hence, it is recommended to adopt a landslide early warning system and suitable remedial measures at Madithorai location.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price includes VAT (Russian Federation)

Instant access to the full article PDF.

Rent this article via DeepDyve

Institutional subscriptions

Data availability

The data generated from the study are included within the article.

Aladejare AE, Akeju VO (2020) Design and sensitivity analysis of rock slope using Monte Carlo simulation. Geotech Geol Eng 38. https://doi.org/10.1007/s10706-019-01048-z . :573 – 85

Ali A, Huang J, Lyamin AV, Sloan SW, Cassidy MJ (2014) Boundary effects of rainfall-induced landslides. Comput Geotech 61:341–354. https://doi.org/10.1016/j.compgeo.2014.05.019

Article   Google Scholar  

Alonso EE (1976) Risk analysis of slopes and its application to slopes in Canadian sensitive clays. Geotechnique 26(3):453–472. https://doi.org/10.1680/geot.1976.26.3.453

Andrewwinner R, Chandrasekaran SS (2021) Investigation on the failure mechanism of rainfall-induced long-runout landslide at Upputhode, Kerala State of India. Land 10(11):1212. https://doi.org/10.3390/land10111212

Annamalai AP, Pranav VS, Aswinth B, Geetha P, Ramkrishnan R (2022) Landscape spatial pattern analysis for Nilgiris District. 2022 IEEE 7th ICRAIE 7:360–366. https://doi.org/10.1109/ICRAIE56454.2022.10054332

ASTM (2012a) Standard test method for direct shear test of soils under consolidated drained conditions. ASTM D3080. ASTM, West Conshohocken, PA

Google Scholar  

ASTM (2012b) Standard test methods for laboratory compaction characteristics of soil using standard effort. ASTM D698. ASTM, West Conshohocken,PA

ASTM (2016) Standard test methods for measurement of soil potential using filter paper. ASTM D5298. ASTM, West Conshohocken, PA

ASTM (2017a) Standard test method for liquid limit plastic limit, and plasticity index of soils. ASTM D4318. ASTM, West Conshohocken,PA

ASTM (2017b) Standard test method for particle-size distribution (gradation) of soils using sieve analysis. ASTM D6913. ASTM, West Conshohocken, PA

Chen RH, Chen HP, Chen KS, Zhung HB (2009) Simulation of a slope failure induced by rainfall infiltration. Environ Geol 58:943–952. https://doi.org/10.1007/s00254-008-1574-8

Cho SE (2010) Probabilistic assessment of slope stability that considers the spatial variability of soil properties. J Geotech GeoEnviron Eng 136(7):975–984. https://doi.org/10.1061/(ASCE)GT.1943-5606.0000309

Cho SE, Lee SR (2002) Evaluation of surficial stability for homogeneous slopes considering rainfall characteristics. Journal of Geotechnical and Geoenvironmental Engineering 128 (9): 756–763. https://doi.org/10.1061/(ASCE)1090-0241 (2002)128:9(756)

Collins BD, Znidarcic D (2004) Stability analyses of rainfall induced landslides. J Geotech Geoenvironmental 130(4):362–372. https://doi.org/10.1061/(ASCE)10900241(2004)130:4(362)

Das P, Patwa D, Bharat TV (2022) Influencing factors on the simulation of rainfall-induced landslide prediction based on case study. Bull Eng Geol Environ 81(5):194. https://doi.org/10.1007/s10064-022-02682-3

Djeffal H, Belkacemi S (2023) Slope Reliability Analysis in locating and observing the direction of failure propagation. Eng Technol Appl Sci Res 13(1):10209–10216. https://doi.org/10.48084/etasr.5509

Fredlund DG (2006) Unsaturated soil mechanics in engineering practice. J Geotech GeoEnviron Eng 132(3):286–321. https://doi.org/10.1061/(ASCE)1090-0241 (2006)132:3(286)

Fredlund DG, Rahardjo H (1993) Soil mechanics for unsaturated soils. Wiley

Gan J, Zhang YX (2020) Analysis of model tests of rainfall-induced soil deposit landslide. Adv Civil Eng 2020:1–13. https://doi.org/10.1155/2020/6431247

Ganapathy GP, Rajawat AS (2015) Use of hazard and vulnerability maps for landslide planning scenarios: a case study of the nilgiris, India. Nat Hazards 77:305–316. https://doi.org/10.1007/s11069-015-1587-z

GeoSlope (2012) Seepage modeling with SEEP/W: an Engineering Methodology. GEO-SLOPE International Ltd.,Canada

Gofar N, Lee ML, Kassim A (2008) Response of suction distribution to rainfall infiltration in soil slope. EJGE 13:1–13

GSI Webpage (Geological Survey of India) (2022) Landslide Hazard. https://www.gsi.gov.in/webcenter/portal/OCBIS/pages_pageGeoInfo/pagelandslidehazard . Accessed 5, August 2023

Harr ME (1987) Reliability-based design in civil engineering. McGraw-Hill, London

Hillel DJ (1980) Fundamentals of soil physics. Academic, New york

Hong M, Jeong S, Kim J (2020) A combined method for modeling the triggering and propagation of debris flows. Landslides 17:805–824. https://doi.org/10.1007/s10346-019-01294-5

Huang SP, Liang B, Phoon KK (2009) Geotechnical probabilistic analysis by collocation-based stochastic response surface method: an Excel add-in implementation. Georisk 3(2):75–86. https://doi.org/10.1080/17499510802571844

Hung C, Liu CH, Chang CM (2018) Numerical investigation of rainfall-induced landslide in mudstone using coupled finite and discrete element analysis. Geofluids 2018:1–15. https://doi.org/10.1155/2018/9192019

Hungr O, Leroueil S, Picarelli L (2014) The Varnes classification of landslide types, an update. Landslides 11:167–194. https://doi.org/10.1007/s10346-013-0436-y

Jain N, Roy P, Martha TR, Jalan P, Nanda A (2023) Landslide Atlas of India (Mapping, monitoring and advance techniques using space-based inputs). NRSC special publication. NRSC/ISRO. Document number: NRSC-RSA-GSG-GMED-FEB 2023-TR-0002167-V1.0 https://www.nrsc.gov.in/ . Accessed 10 February 2024

Jaiswal P (2011) Landslide risk quantification along transportation corridors based on historical information, ITC doctoral dissertation, The Netherlands

Jeldes IA, Drumm EC, Schwartz JS (2014) Partial saturation and seismicity on steep reclaimed slopes. Geotech Geol Eng 32:1065–1079. https://doi.org/10.1007/s10706-014-9781-4

Kim KS, Jeong SW, Song YS, Kim M, Park JY (2021) Four-year monitoring study of shallow landslide hazards based on hydrological measurements in a weathered granite soil slope in South Korea. Water 13(17):2330. https://doi.org/10.3390/w13172330

Article   CAS   Google Scholar  

Lakshumanan C, Kishore YP, Yiveganandan S, Krishnakumar P, Muthusankar G (2012) Landuse/land cover dynamics study in Nilgiris district part of western ghats, Tamilnadu. Int J Geomatics Geosci 2(3):911–923

Li DQ, Jiang SH, Cao ZJ, Zhou W, Zhou CB, Zhang LM (2015) A multiple response-surface method for slope reliability analysis considering spatial variability of soil properties. Eng Geol 187:60–72. https://doi.org/10.1016/j.enggeo.2014.12.003

Li C, Wang G, He J, Wang Y (2022) A novel approach to probabilistic seismic landslide hazard mapping using Monte Carlo simulations. Eng Geol 301:106616. https://doi.org/10.1016/j.enggeo.2022.106616

Lim TT, Rahardjo H, Chang MF, Fredlund DG (1996) Effect of rainfall on matric suctions in a residual soil slope. Can Geotech J 33(4):618–628. https://doi.org/10.1139/t96-087

Lu N, Godt J (2008) Infinite slope stability under steady unsaturated seepage conditions. Water Resour Res 44(11). https://doi.org/10.1029/2008WR006976

Lu N, Wayllace A, Oh S (2013) Infiltration-induced seasonally reactivated instability of a highway embankment near the Eisenhower Tunnel, Colorado, USA. Eng Geol 162:22–32. https://doi.org/10.1016/j.enggeo.2013.05.002

Lumb P (1966) The variability of natural soils. Can Geotech J 3(2):74–97. https://doi.org/10.1139/t66-009

Malaya C, Sreedeep S (2011) Critical review on the parameters influencing soil-water characteristic curve. J Irrig Drain Eng 138(1):55–62. https://doi.org/10.1061/(ASCE)IR.1943-4774.0000371

Mallick J, Alqadhi S, Talukdar S, AlSubih M, Ahmed M, Khan RA, Abutayeh S (2021) Risk assessment of resources exposed to rainfall induced landslide with the development of GIS and RS based ensemble metaheuristic machine learning algorithms. Sustainability 13(2):457. https://doi.org/10.3390/su13020457

Mathangi B, Zaalishvili VB, Ganapathy GP (2023) Study of substrata of a slope susceptible to landslide in hilly environment using a geophysical method in the nilgiris, India. Environ Sci Pollut Res 30:123966–123982. https://doi.org/10.1007/s11356-023-30809-w

Matyas EL (1977) Probabilistic analysis of predicted and measured settlements: discussion. Can Geotech J 14(1):159–163. https://doi.org/10.1139/t77-016

Nadim F, Kjekstad O, Domaas U, Rafat R, Peduzzi P (2006) Global landslides risk case study. Natural disaster hotspots, case studies. Disaster risk Manage Ser 6:21–77

Oh WT, Vanapalli SK (2010) Influence of rain infiltration on the stability of compacted soil slopes. Comput Geotech 37(5):649–657. https://doi.org/10.1016/j.compgeo.2010.04.003

Pan Q, Zhang R, Wang S, Chen J, Zhang B, Zou J, Yang X (2023) Three-dimensional stability of slopes under water drawdown conditions. Int J Geomech 23(1):04022254. https://doi.org/10.1061/(ASCE)GM.1943-5622.0002614

Pardhasaradhi YJ, Vaidyanadhan R (1974) Evolution of Landforms over the Nilgiri, South India. Geol Soc India 15(2):182–188

Phoon KK, Kulhawy FH (1999) Characterization of geotechnical variability. Can Geotech J 36(4):612–624

Qi S, Vanapalli SK (2015) Hydro-mechanical coupling effect on surficial layer stability of unsaturated expansive soil slopes. Comput Geotech 70:68–82. https://doi.org/10.1016/j.compgeo.2015.07.006

Qian ZH, Zou JF, Pan QJ (2021) 3D discretized rotational failure mechanism for slope stability analysis. Int J Geomech 21(11):04021210. https://doi.org/10.1061/(ASCE)GM.1943-5622.0002163

Raghuram AS, Basha BM (2020) Analysis of rainfall-induced slope failure using Monte Carlo simulations: a case study. Geohazards 86:111–127. https://doi.org/10.1007/978-981-15-6233-4_8

Raghuram ASS, Basha BM (2021) Second-order reliability-based design of unsaturated infinite soil slopes. Int J Geomech 21(4):04021024. https://doi.org/10.1061/(ASCE)GM.1943-5622.0001954

Rahardjo H, Li XW, Toll DG, Leong EC (2001) The effect of antecedent rainfall on slope stability. Unsaturated soil Concepts Their Application Geotech Pract 371–399. https://doi.org/10.1007/978-94-015-9775-3_8

Rahardjo H, Ong TH, Rezaur RB, Leong EC (2007) Factors controlling instability of homogeneous soil slopes under rainfall. Journal of geotechnical and geoenvironmental engineering 133 (12): 1532–1543. https://doi.org/10.1061/(ASCE)1090-0241 (2007)133:12(1532)

Rahimi A, Rahardjo H, Leong EC (2011) Effect of antecedent rainfall patterns on rainfall-induced slope failure. J Geotech GeoEnviron Eng 137(5):483–491. https://doi.org/10.1061/(ASCE)GT.1943-5606.0000451

Senthilkumar V, Chandrasekaran SS, Maji VB (2017) Overview of rainfall induced landslide events and importance of geotechnical investigations in Nilgiris District of Tamil Nadu, In: Mikos M, Casagli N, Yin Y, Sassa K(eds) of Proc., 4th World Landslide Forum, Springer, vol 4, pp 281–287

Senthilkumar V, Chandrasek aran SS, Maji VB (2018) Rainfall-induced landslides: case study of the Marappalam landslide, Nilgiris District, Tamil Nadu, India. Int J Geomech 18(9):05018006. https://doi.org/10.1061/(ASCE)GM.1943-5622.0001218

Seshagiri DN, Badrinarayanan S, Upendran R, Lakshmikantham CB, Srinivasan V (1982) The Nilgiris landslides: results of geotechnical and geological investigations of the GSI in collaboration with state geology branch. Geological Survey of India

Sivakumar Babu GL, Murthy DS (2005) Reliability analysis of unsaturated soil slopes. J Geotech GeoEnviron Eng 131(11):1423–1428. https://doi.org/10.1061/(ASCE)1090-0241(2005)131:11(1423)

Sreedeep S, Singh DN (2011) Critical review of the methodologies employed for soil suction measurement. Int J Geomech 11(2):99–104. https://doi.org/10.1061/(ASCE)GM.1943-5622.0000022

Thennavan E, Ganapathy G, Chandrasekaran S, Rajawat A (2020) Probabilistic rainfall thresholds for shallow landslides initiation–A case study from the Nilgiris district, western ghats, India. Int J Disaster Risk Manage 2(1):1–4. https://doi.org/10.18485/ijdrm.2020.2.1.1

Thennavan E, Ganapathy GP, Chandra Sekaran SS, Rajawat AS (2016) Use of GIS in assessing building vulnerability for landslide hazard in The Nilgiris, Western Ghats, India. Nat Hazards 82:1031-1050. https://doi.org/10.1007/s11069-016-2232-1

Tsaparas I, Rahardjo H, Toll DG, Leong EC (2002) Controlling parameters for rainfall-induced landslides. Comput Geotech 29(1):1–27

TWAD Board Webpage (TamilNadu Water Supply and Drainage Board) (2023) Nilgiri district profile. https://www.twadboard.tn.gov.in/content/nilgiri . Accessed 7 August 2023

USACE (United States Army Corps of Engineers) (1999) Risk-based analysis in geotechnical engineering for support of planning studies, engineering and design. Rep. No. 20314 – 1000. Dept. of Army, USACE, Washington, DC

Uzielli M, Lacasse S, Nadim F, Phoon KK (2006) Soil variability analysis for geotechnical practice. Charact Eng Prop Nat Soils 3:1653–1752

Vadivel S, Sennimalai CS (2019) Failure mechanism of long-runout landslide triggered by heavy rainfall in Achanakkal, Nilgiris, India. J Geotech GeoEnviron Eng 145(9):04019047. https://doi.org/10.1061/(ASCE)GT.1943-5606.0002099

Van Genuchten MT (1980) A closed-form equation for predicting the hydraulic conductivity of unsaturated soils. Soil Sci Soc Am J 44(5):892–898. https://doi.org/10.2136/sssaj1980.03615995004400050002x

Vanapalli SK, Fredlund DG, Pufahl DE, Clifton AW (1996) Model for the prediction of shear strength with respect to soil suction. Can Geotech J 33(3):379–392. https://doi.org/10.1139/t96-060

Varnes DJ (1978) Slope movement types and processes. Special Rep 176:11–33

Vishnu G, Bharat TV (2021) Numerical Investigation on the influence of different parameters on a Vegetated Slope-A Case Study. Foundation Forensic Geotech Eng 295:287–297. https://doi.org/10.1007/978-981-19-6359-9_27

Wang Y, Cao Z, Au SK (2011) Practical reliability analysis of slope stability by advanced Monte Carlo simulations in a spreadsheet. Can Geotech J 48(1):162–172. https://doi.org/10.1139/T10-04

Wang CH, Fang L, Chang DT, Huang FC (2023) Back-analysis of a rainfall-induced landslide case history using deterministic and random limit equilibrium methods. Eng Geol 317:107055. https://doi.org/10.1016/j.enggeo.2023.107055

Wei L, Cheng H, Dai Z (2023) Propagation modeling of Rainfall-Induced landslides: a case study of the Shaziba Landslide in Enshi, China. Water 15(3):424. https://doi.org/10.3390/w15030424

Yamaguchi Y, Makinoshima F, Oishi Y (2023) Simulating the entire rainfall-induced landslide process using the material point method for unsaturated soil with implicit and explicit formulations. Landslides 20:1617–1638. https://doi.org/10.1007/s10346-023-02052-4

Yang Y, Wu W, Zheng H (2023) Investigation of slope stability based on strength-reduction-based numerical manifold method and generalized plastic strain. Int J Rock Mech Min Sci 164:105358. https://doi.org/10.1016/j.ijrmms.2023.105358

Yuvaraj RM, Dolui B (2021) Statistical and machine intelligence-based model for landslide susceptibility mapping of Nilgiri district in India. Environ Challenges 5:100211. https://doi.org/10.1016/j.envc.2021.100211

Zhang S, Pecoraro G, Jiang Q, Calvello M (2023) Definition of Rainfall Thresholds for landslides using Unbalanced datasets: two Case studies in Shaanxi Province, China. Water 15(6):1058. https://doi.org/10.3390/w15061058

Zhou G, Esaki T, Mitani Y, Xie M, Mori J (2003) Spatial probabilistic modeling of slope failure using an integrated GIS Monte Carlo simulation approach. Eng Geol 68(3–4):373–386

Download references

Acknowledgements

This article is a component of the author’s doctoral studies at the National Institute of Technology Puducherry in India, which are being supervised by the corresponding author. The corresponding author is appreciative of the support received from NIT Puducherry in order to complete this research work.

Author information

Authors and affiliations.

Department of Civil Engineering, National Institute of Technology Puducherry, Karaikal, Puducherry, 609609, India

Bhavithra Soundararajan & Senthilkumar Vadivel

Centre for Disaster Mitigation and Management (CDMM), Vellore Institute of Technology, Vellore, Tamil Nadu, 632014, India

Chandrasekaran Sembulichampalayam Sennimalai

You can also search for this author in PubMed   Google Scholar

Corresponding author

Correspondence to Senthilkumar Vadivel .

Ethics declarations

Competing interests.

The authors declare no competing interests.

Additional information

Publisher’s note.

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Reprints and permissions

About this article

Soundararajan, B., Vadivel, S. & Sembulichampalayam Sennimalai, C. Investigation of rainfall-induced landslide on unsaturated lateritic residual soil slope in Nilgiris, Western Ghats, India using deterministic and reliability analysis. Bull Eng Geol Environ 83 , 221 (2024). https://doi.org/10.1007/s10064-024-03704-y

Download citation

Received : 25 October 2023

Accepted : 20 April 2024

Published : 11 May 2024

DOI : https://doi.org/10.1007/s10064-024-03704-y

Share this article

Anyone you share the following link with will be able to read this content:

Sorry, a shareable link is not currently available for this article.

Provided by the Springer Nature SharedIt content-sharing initiative

• Reliability analysis
• Unsaturated soil slopes
• Transient seepage
• Stability analysis
• Find a journal
• Publish with us
• Track your research