What If an Intense Rain Event Should Trigger Diffuse Shallow Landslides in a Small Mediterranean Catchment? Numerical Modeling Through Remote Sensing Techniques

Abstract

The Mediterranean region is increasingly experiencing intense and short-term rainfall, whose effects on the ground trigger widespread and quickly evolving phenomena including debris flows and shallow landslides which cause damage to buildings and infrastructure and occasionally even loss of life. In this research, we focus on the central Mediterranean in an area exposed to high-intensity rainfall that impacts small catchments which have been intensively anthropogenically modified through the years. The Portofino Promontory is characterized by a high cultural and landscape value where nature and historical anthropogenic landforms and signs coexist. The Promontory attracts tourists from all over the world, but it is exposed to a high number of hazards related to debris–mud flow processes that may impact cultural heritage, tourism facilities and infrastructure. In addition, the ancient man-made terraces that are widespread along the Promontory’s slopes may play the role of being a source for shallow landslides, as this similarly happens in many Mediterranean regions. In 2011, heavy rainfall impacted the similar landscape of the Cinque Terre, triggering hundreds of small mud–debris flows whose combined effect was devastating. To this end, a ground effects simulation was developed as part of the H2020 project RECONECT which aims to contribute to a European reference framework on nature-based solutions, based on the high-detail and -precision remote sensing data acquired within the project. The data allowed us to assess the triggering areas, the transport channel, the observed deposition zones and the interaction with the exposed elements before building a possible risk scenario. The simulation and the entire approach may be upscaled to many similar areas where shallow landslide hazards originating from man-made terraces threatens buildings, cultural heritage, tourism facilities and infrastructure.