Typical disaster-pregnant patterns and remote sensing identification indicators of bedded rock landslides in the head area of the Three Gorges Reservoir, Yangtze River

Objective Revealing disaster−pregnant patterns is an important prerequisite for hidden danger identification. However, comprehensive understanding and summarization of such patterns for bedded rock reservoir landslides in the specific geological setting of the Zigui basin are still lacking, and targeted remote−sensing indicators for their early detection rcemain absent—making systematic research urgently needed.

Methods Three bedding−rock slope sectors with frequent landsliding in the Zigui syncline basin at the head of the Three Gorges Reservoir—namely the Shazhenxi reach (at the confluence of the Qinggan and Luogudong rivers), the left bank of the Zhaxi River and the left bank of the Xietan River—constitute the study area. Data collection, field investigations and UAV−based surveys were conducted to analyse the disaster−pregnant mechanisms of seven typical bedded rock landslides.

Results The system is generalized and five typical models are proposed, which are bedding slip−bending type, bedding slip−pulling type, bedding push type, wedge−bedding slip type and wedge combination−step slip type. On this basis, according to its common disaster−pregnant characteristics, a remote sensing identification sign system of bedding rock landslide in the head of the Three Gorges Reservoir is established, which is composed of five first−level signs (structural characteristics, stratigraphic lithology, topography, hydrology information, boundary conditions) and eight second−level signs (bank slope structure, stratigraphic age, stratigraphic color, surface morphology, geomorphological conditions, river characteristics, leading edge boundary, bilateral boundary).

Conclusions The five disaster−pregnant patterns together with the "5 first−level + 8 second−level" remote−sensing indicators can effectively guide desktop hazard identification, provide a transferable workflow for early detection of similar bedding slopes in the Three Gorges head region, and serve as a methodological reference for landslide investigations under comparable geological conditions in other reservoir areas.