Coastal Landslide Analysis within the RESONANCE Project

Coastal landslides and cliff instabilities are increasingly affecting the Adriatic coastline due to climate change-driven extreme events, long-term marine erosion and growing anthropogenic pressures. These processes pose significant threats to coastal infrastructure, ecosystems and public safety, highlighting the need for advanced monitoring, analysis and decision-support tools. Within this context, the Interreg Italy-Croatia RESONANCE project aims to enhance hydrogeological risk prevention and management in coastal areas through the integration of high-resolution surveying techniques, numerical modelling and innovative digital visualization approaches.

This contribution presents the main activities and preliminary results of a study focused on the characterization and analysis of coastal slope instabilities at selected pilot sites along the Adriatic Sea. Four representative coastal settings were investigated, encompassing different geological and geomorphological conditions and a range of instability mechanisms, including rockfalls, topples and structurally controlled failures affecting rocky cliffs.

Data acquisition followed a multi-sensor and multi-scale approach integrating UAV-borne laser scanning, close-range photogrammetry and UAV-based thermal imaging, complemented by detailed in situ geomechanical surveys. UAV laser scanning and photogrammetry enabled the generation of ultra-high-resolution three-dimensional point clouds and digital surface models, providing a robust basis for detailed geomorphological mapping and structural analysis of rock masses. Thermographic surveys supplied additional information on thermal anomalies related to moisture distribution, fracture connectivity and potential zones of weakness within the cliffs. Field-based geomechanical investigations focused on the characterization of discontinuity networks, including orientation, spacing, persistence and surface conditions, providing key parameters for stability analyses.

A particular emphasis was placed on multi-temporal surveys, which are essential for understanding the short- to medium-term evolution of coastal cliffs. Repeated UAV acquisitions allowed the detection of subtle morphological changes, the quantification of erosion and retreat rates, and the identification of localized instability processes driven by meteomarine forcing, rainfall events and extreme climatic conditions. These datasets offer valuable constraints for assessing the temporal dynamics of coastal instability and for identifying sectors characterized by increasing susceptibility to failure.

The high-resolution three-dimensional models derived from remote sensing were subsequently employed for numerical modelling aimed at investigating failure mechanisms and controlling factors. The modelling outcomes highlighted the key parameters governing cliff stability and provided insights into the potential impacts of climate-related changes, such as increased storm frequency and rainfall intensity, on coastal slope instability.

In parallel with surveying and modelling activities, the study contributed to the development of advanced digital tools based on virtual, augmented and mixed reality (VR/AR/MR), which represent a core innovation of the RESONANCE project. These tools integrate three-dimensional models, multi-temporal datasets and numerical simulation outputs into immersive and interactive environments, enabling intuitive visualization of coastal instability processes and realistic failure scenarios. Such platforms have strong potential to support risk communication and decision-making by improving the understanding of complex geomorphological dynamics.

Overall, the results demonstrate that the integration of multi-source remote sensing, numerical modelling and immersive visualization provides an effective and innovative framework for the analysis of coastal landslides, supporting improved assessment and management of hydrogeological risk along the Adriatic coastline.