Abstract
Over the years, India has experienced numerous rainfall-triggered landslides that initiate complex multi-hazard events, resulting in substantial human loss. This study presents a graph-based risk assessment of multi-hazards for two case studies in India: The South Lhonak Lake Glacial Lake Outburst Flood which impacted North Sikkim in October 2023 and the Wayanad Landslides in July 2024, which collectively claimed over 600 lives. This is achieved through a multidimensional methodology which integrates dynamic rainfall and discharge thresholds, stakeholder-informed hazard sequences, spatiotemporal hazard progression, and elements at risk. Heterogeneous data sources including remote sensing, field surveys, hydro-meteorological observations, and gray literature such as government reports and official situation bulletins, are synthesized to construct weighted, directed hazard networks. Graph-theory metrics, including degree centrality, betweenness centrality, and cascade depth, are used to compute sub-basin-level risk scores. Results highlighted critical sequences present in both regions, particularly the transition from extreme rainfall to landslides and subsequent flooding. Also, they identified high-risk zones influenced by both topography and infrastructure exposure. The findings emphasize the need for real-time threshold monitoring and alert systems, hazard-sequence-based operational protocols, and spatiotemporally phased response planning to support coordinated evacuations and early warning. The proposed framework offers actionable guidance for dynamic risk monitoring and multi-hazard governance in vulnerable mountain ecosystems.
Data availability
Daily rainfall data were obtained from rain gauge stations of the Indian Meteorological Department (available at: [https://mausam.imd.gov.in/](https:/mausam.imd.gov.in)) and the Central Water Commission (available at: [https://indiawris.gov.in/wris/](https:/indiawris.gov.in/wris)). The ALOS PALSAR DEM was obtained from the Alaska Satellite Facility DAAC (ASF DAAC) (available at: [https://search.asf.alaska.edu/](https:/search.asf.alaska.edu)).
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Acknowledgements
I thank our Chancellor, Sri Mata Amritanandamayi Devi (AMMA), for her exemplary vision of selfless service and compassion in addressing complex problems in communities worldwide. I would like to thank Dr. Aadityan Sridharan, Dr. Dhanya Madhu, Mr. Nitin Kumar M., Mr. Balmukund Singh, and Dr. Sabari Ramesh for their assistance during the field visits in Sikkim and Wayanad. I would like to thank Dr. Bhavani Rao and the entire team from the Amrita School of Social and Behavioral Sciences for their assistance in conducting the stakeholder consultations in Wayanad. I am grateful to the Amrita Live-in-Labs® academic program for providing all the support. Lastly, I sincerely thank the editors and reviewers for their careful evaluation and constructive comments, which have significantly improved the clarity, rigor, and overall quality of the manuscript.
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Open access funding provided by Amrita Vishwa Vidyapeetham. This project has been funded by the E4LIFE International Ph.D. Fellowship program offered by Amrita Vishwa Vidyapeetham.
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M.V.R. conceived the study, supervised the research, and provided critical feedback. H.C.E. contributed to data analysis, interpretation and wrote the manuscript. All authors reviewed and approved the manuscript.
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All stakeholder interaction methods were carried out according to relevant guidelines and regulations, including institutional and national ethical standards. The study protocols were reviewed and approved by the ethical committee of Amrita Vishwa Vidyapeetham (Ref No: IHEC/2025/198). Local language-speaking volunteers were used to conduct stakeholder interactions, and informed consent was obtained from all participants involved in the study.
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Ekkirala, H.C., Ramesh, M.V. Spatiotemporal assessment of multi hazard risk using graph based analysis for case studies in India. Sci Rep (2026). https://doi.org/10.1038/s41598-026-35925-4
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DOI: https://doi.org/10.1038/s41598-026-35925-4