ANALYSIS OF SOLID TRANSPORT IN TORRENTIAL WATERCOURSES FOR HYDRAULIC AND HYDROGEOLOGICAL RISK MANAGEMENT

Climate change is intensifying the frequency and magnitude of extreme weather events across Mediterranean regions, increasing the exposure of mountainous catchments to flash floods and related geomorphic hazards. To predict their morphological response and mitigate future impacts, it is essential to understand how sediment is supplied, transferred, and redistributed within these systems. This research integrates two complementary approaches to analyse sediment dynamics in the Burano River basin (Central Apennines, Italy), severely affected by the 15–16 September 2022 extreme flood. It is becoming more widely acknowledged that promoting the sustainable use of natural resources and reducing environmental consequences depend on effective sediment control and management. This thesis aims to investigate the intricate interactions between hydrodynamic forces, sediment delivery, and sediment availability, which are critical in determining how rivers react to extreme occurrences. In the first phase, a GIS-based framework was developed to identify and prioritise sediment supply areas and evaluate their structural connectivity using morphometric indices such as the Stream Power Index (SPI), Connectivity Index (IC), and Stream Length-Gradient Index (SL). The method has proven effective in identifying the spatial distribution of sediment source and connecting transport channels by considering the coupling processes between slopes and river channels. This approach is both time and cost-efficient and provides reliable information on sediment transfer with minimal input data requirements. In the second phase, a two-dimensional morphodynamic model (Iber) was applied to a critical Burano sub-basin (Tenetra stream) to simulate bed-load and riverbed evolution under the 2022 flood event conditions. Different scenarios of coarse sediment grain-size distribution (D₅₀) and abrupt sediment inputs were tested to assess how variability in sediment characteristics influences bed-load transport, channel morphology, and the efficiency of existing hydraulic works. The results of these applied techniques should offer important new information about the function of sediment availability, sediment supply understanding the river response to a grain-size variation in terms of morphological changes during flood events, both in the river under study and in similar fluvial systems. The integrated approach highlights how sediment availability and connectivity strongly control geomorphic adjustments during floods. Results demonstrate that neglecting bed-load transport can lead to underestimation of flood hazards, as morphological changes modify channel geometry, roughness, and flow conveyance capacity. The methodology offers a reproducible, time-efficient tool to support emergency planning and sediment management, providing valuable insights for predicting river responses to future extreme events and designing adaptive flood mitigation strategies in similar mountainous contexts.