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

Ajin, R. S.; Nandakumar, D.; Rajaneesh, A.; Oommen, Thomas; Ali, Yunus P.; Sajinkumar, K.S.

doi:10.1186/s40677-022-00218-1

Cited by 26 publications

(6 citation statements)

References 21 publications

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“…Two such major landslides that were reported on 16 October 2021, were in the Koottickal village of the Kottayam district (Figure 1). These landslides resulted in the deaths of ten people (four at Plappally and six at Kavali) [10]. Such catastrophic landslides demand the necessity of relooking into the existing landslide susceptibility map and warrant additional models if required.…”

Section: Introductionmentioning

confidence: 99%

Landslide Susceptibility Assessment of a Part of the Western Ghats (India) Employing the AHP and F-AHP Models and Comparison with Existing Susceptibility Maps

Bhagya

Sumi

Balaji

et al. 2023

Land

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Landslides are prevalent in the Western Ghats, and the incidences that happened in 2021 in the Koottickal area of the Kottayam district (Western Ghats) resulted in the loss of 10 lives. The objectives of this study are to assess the landslide susceptibility of the high-range local self-governments (LSGs) in the Kottayam district using the analytical hierarchy process (AHP) and fuzzy-AHP (F-AHP) models and to compare the performance of existing landslide susceptible maps. This area never witnessed any massive landslides of this dimension, which warrants the necessity of relooking into the existing landslide-susceptible models. For AHP and F-AHP modeling, ten conditioning factors were selected: slope, soil texture, land use/land cover (LULC), geomorphology, road buffer, lithology, and satellite image-derived indices such as the normalized difference road landslide index (NDRLI), the normalized difference water index (NDWI), the normalized burn ratio (NBR), and the soil-adjusted vegetation index (SAVI). The landslide-susceptible zones were categorized into three: low, moderate, and high. The validation of the maps created using the receiver operating characteristic (ROC) technique ascertained the performances of the AHP, F-AHP, and TISSA maps as excellent, with an area under the ROC curve (AUC) value above 0.80, and the NCESS map as acceptable, with an AUC value above 0.70. Though the difference is negligible, the map prepared using the TISSA model has better performance (AUC = 0.889) than the F-AHP (AUC = 0.872), AHP (AUC = 0.867), and NCESS (AUC = 0.789) models. The validation of maps employing other matrices such as accuracy, mean absolute error (MAE), and root mean square error (RMSE) also confirmed that the TISSA model (0.869, 0.226, and 0.122, respectively) has better performance, followed by the F-AHP (0.856, 0.243, and 0.147, respectively), AHP (0.855, 0.249, and 0.159, respectively), and NCESS (0.770, 0.309, and 0.177, respectively) models. The most landslide-inducing factors in this area that were identified through this study are slope, soil texture, LULC, geomorphology, and NDRLI. Koottickal, Poonjar-Thekkekara, Moonnilavu, Thalanad, and Koruthodu are the LSGs that are highly susceptible to landslides. The identification of landslide-susceptible areas using diversified techniques will aid decision-makers in identifying critical infrastructure at risk and alternate routes for emergency evacuation of people to safer terrain during an exigency.

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Section: Introductionmentioning

confidence: 99%

Landslide Susceptibility Assessment of a Part of the Western Ghats (India) Employing the AHP and F-AHP Models and Comparison with Existing Susceptibility Maps

Bhagya

Sumi

Balaji

et al. 2023

Land

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“…In 2019, the Puthumala landslide caused the death of 81 people (Wadhawan et al, 2020), and 66 tea estate workers perished in the landslide that occurred in Pettimudi in 2020 (Achu et al, 2021). In 2021, the Kootickal and Kokkayar slides caused 18 deaths (Ajin et al, 2022;Sisira and Mohanan). Kerala has been affected by debris flow type landslides (Achu et al, 2021;Kuriakose et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Hydrometeorological Landslides on the Windward Side of Western Ghats – A Case Study of Kootickal, Kerala, India

Amrutha¹,

Varghese²,

Prakash³

et al. 2023

J. Geospat. Surv.

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On the windward side of Western Ghats, the frequency of landslides has significantly increased in recent years. Kerala had catastrophic landslides and floods in 2018, 2019, 2020, and 2021, resulting in loss of lives and property. On October 2021, a cloudburst occurred in middle Kerala, causing multiple devastating landslides in districts of Kottayam and Idukki. The study focused on how the topographic, physical, geological, and anthropogenic factors in the windward slope of the Western Ghats influence the occurrence of landslides. The landslide susceptibility was analyzed using the frequency ratio method on the basis of recently occurred landslide locations in the Manimala river basin, with special reference to Kootikal. The impact of each factor was analyzed against the GPS coordinates of landslide locations to estimate the frequency ratio value. The findings revealed that the torrential rainfall experienced in Kerala and the anthropogenic activities, especially the watershed management work performed in the area, significantly increased landslide susceptibility of the basin. About 5% of Manimala river basin is highly susceptible to landslides, and this area comes under the Kootikal sub-basin. The study recommends a rigorous geophysical assessment on the influence of watershed management operations on a landslide and an EIA of roads in the Kootickal region.

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“…Mountainous areas often suffer economic losses due to landslides since they damage communication links, destroy fertile soil, and kill people. In developing countries like India, landslides are among the signi cant disasters (Pande 2006; Haigh and Rawat 2012; Achu et al 2021;Hao et al 2022;Ajin et al 2022). On October 14th, 2021, the low-pressure system developed in the east-central Arabian Sea and drastically changed the weather conditions in Kerala.…”

Section: Introductionmentioning

confidence: 99%

“…In comparison, it was 1270 mm in October 2021. From the Hyetograph of the Kanjirappally rain gauge, which is the nearest to the landslide-affected area, the prominent 266 mm of rainfall occurred only on October 16th 2021, the landslide day(Ajin et al, 2022).…”

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confidence: 99%

A Study on the Geo-Environmental and Social Impacts of Koottickal and Kokkayar Landslides

krishnan,

Jacob,

Stanly

et al. 2023

Preprint

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Many countries allocate significant resources and labour to mitigate natural hazards, particularly landslides, due to their potential for casualties, property damage, and loss of life worldwide. Over the years, geotechnical and environmental investigations have been conducted to gain a better understanding of landslides. Heavy rain on October 16th, 2021, triggered a devastating landslide in Kerala. Thirteen people were killed, and significant damage was caused by the landslides in Koottickal (Kottayam) and Kokkayar (Idukki). Two separate landslides were reported in Plappalli and Kavali, destroying three shops and three houses. In addition, two footbridges and five bridges were structurally damaged. The study explores the geo-environmental and social characteristics of this catastrophic event due to the heavy rainfall and infiltration around highly fragile and vulnerable geographical surroundings. An environmental Study of the Koottickal and Kokkayar landslide examined the adverse effects on the environment, focusing on the sediment transport that destroyed flora and contamination of water resources that resulted in water pollution. As a result of analysing primary and secondary data, the effects of the landslide have been identified to some extent. Social impacts of the Koottickal landslide have been discussed considering the future development of Koottickal and Kokkayar village as a tourist destination, maintaining the diversity of flora and fauna, and conserving the water source, the perennial river Manimala, which keeps the village a fertile land. Geotechnical and environmental characteristics of the soil are examined in the study. It aims to contribute to a better understanding of landslide dynamics, help formulate effective mitigation strategies, and promote sustainable development practices in landslide-prone areas.

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

Cited by 26 publications

References 21 publications

Landslide Susceptibility Assessment of a Part of the Western Ghats (India) Employing the AHP and F-AHP Models and Comparison with Existing Susceptibility Maps

Landslide Susceptibility Assessment of a Part of the Western Ghats (India) Employing the AHP and F-AHP Models and Comparison with Existing Susceptibility Maps

Hydrometeorological Landslides on the Windward Side of Western Ghats – A Case Study of Kootickal, Kerala, India

A Study on the Geo-Environmental and Social Impacts of Koottickal and Kokkayar Landslides

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