Abstract
Several landslides and floods were triggered by unprecedented, incessant heavy monsoon rainfall from 4 August 2019 to 8 August 2019, along the northern slopes, at Kavalappara, in the Malappuram district and Puthumala, in the Wayanad district of Kerala, India. The geological and geomorphological field settings were analyzed within the sub-basin wide catchment areas, for a preliminary evaluation of the causative factors of the landslides. This paper provides insights into the causative factors of landslides, together with suggestions on appropriate land use planning and deployment of real-time flood and landslide monitoring systems, besides building an adaptable community resilience model in high landslide-prone areas. The structurally disturbed weakened bedrocks and generally incompetent residual alteration products, exacerbated by nonchalant human interventions, reduction of cohesive strength, on super-saturation of underlying earth material, were inferred to be the primary causes of major landslides, triggered during 5 days of excessively heavy rainfall (400% over the normal average). Additionally, massive toe erosion was observed by streams gushing with course clastic sediments and debris. The destructive nature of such multi-hazards was evoked by unscientific modifications of slopes, mismanagement of water drainage, unplanned residential developments, across the channel courses and within active floodplain of rivers, and lack of early warning schemes for landslide.
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Acknowledgments
The authors would like to express gratitude for the immense amount of motivation and guidance provided by Dr. Sri. Mata Amritanandamayi Devi, the Chancellor, Amrita Vishwa Vidyapeetham. We thank Dr. Nirmala Vasudevan, Mr. Kaushik Ramanathan, Mr. Anshu, Mr. Sudarsan Navada, Mr. Ramesh Guntha, Mr. Ratish, Ms. Hemalatha, Mr. Gopalaiengar Sheshadri, and other staff members from Amrita Vishwa Vidyapeetham for their valuable support and suggestions. Amrita Vishwa Vidyapeetham, Kollam, Kerala, funded for this work under the project “Community Based Disaster Resilience through Landslide Early Warning System.” Anonymous reviewers are thanked for their suggestions that improved the manuscript. This report is a part of activities of the World Centre of Excellence on Landslide Risk Reduction (WCoE 2017-2020) “Enhancement of the existing Real-time Landslide Monitoring and Early warning System in Western Ghats & Himalayas, India” conducted by Amrita Vishwa Vidyapeetham (Leader: Maneesha Vinodini Ramesh).
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Wadhawan, S.K., Singh, B. & Ramesh, M.V. Causative factors of landslides 2019: case study in Malappuram and Wayanad districts of Kerala, India. Landslides 17, 2689–2697 (2020). https://doi.org/10.1007/s10346-020-01520-5
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DOI: https://doi.org/10.1007/s10346-020-01520-5