An interdisciplinary analytical framework for high-mountain landslides and cascading hazards: implications for communities and infrastructure

In the wake of climate change, there is an ever-increasing need to bring socioeconomic (SE) and critical infrastructure (CI) perspectives within conventional physical hazard assessment models. High-mountain hazards impact lives of some of the most vulnerable communities globally. The exposure to and the frequency of hazards have increased and are highest for events such as landslides and cascading hazards, prevalent in mountains. We aim at developing an interdisciplinary analytical framework for identifying and assessing the risks to communities and CI from landslides and cascading glacial hazards. While the framework will be applicable to any high-mountain region, we will implement and test it for Bhagirathi and Bhilangana Valleys, known for their hydrological, hydropower, touristic, and religious significance. The designed workflow blends cutting-edge geoscience and social science research to develop new insights enabling the amelioration of the hazard risks.

Targeting the existing research gap on spatiotemporal spread of landslides in Himalaya, our research will be performed at two spatial scales: (1) mapping, analysing, and understanding the direct hazardous impacts of landslides, and (2) modelling the indirect but cascading hazardous impacts of glacial landslides. In addition to mapping and modelling the events, the project also incorporates SE and CI factors, and community perceptions within the assessment and mitigation plans. While we will use high-resolution satellite datasets of past ~20 years to generate a multi-temporal landslide inventory, we will also use dendrogeomorphology methods to extend this inventory to past ~100 years of timescale, deducing the landslide patterns with respect to extreme weather, infrastructure development, and climate shifts. Furthermore, the relationship between rock characteristics/composition and the landslide failure mechanism needs more investigations. Such holistic and interdisciplinary framework covering all the aforementioned aspects on landslides for a high-mountain catchment is yet to be adopted and can set a benchmark for similar research in other high-mountain regions.

The main objectives are: (1) to develop a temporally exhaustive landslide inventory using Earth Observation (EO) data and tree ring-based reconstructions, and understand their evolution with respect to extreme weather events and CI projects, (2) to assess the direct hazard impact of landslides on CI and habitation through spatial and demographic analyses, (3) to model the impacts of cascade hazard potential of glacial landslides at the identified sites, (4) to perform geotechnical analysis to understand the relationship between slope failure and slope material compositions and characteristics in this region, (5) to understand the community perception of hazards (with respect to land use and transhumance patterns, trade and migration routes, and kinship and alliance distributions), and (6) To design community-based and socially acceptable mitigation guidelines.

The anticipated outcomes will be beneficial to high-mountain communities, taking a step towards mitigation through preparedness and increased awareness. The multi-temporal landslide inventory will help assess the hazard-prone regions for present and future CI. The community perception of hazards will further inform policy makers on acting accordingly while implementing the mitigation measures. The tree-ring-based reconstruction of past frequency series will serve as an excellent basis for the calibration and accuracy assessment of process-based landslide cascade simulation models. As a future prospect of the geotechnical investigations, the improved understanding on the relationship between slope failure mechanism and slope material compositions and characteristics in this region, will help develop reliable geotechnical models on landslide prediction.