Torrent Control Structures Monitoring: a Regional Scale Index based on Inventory Analysis and Remote Sensing

Monitoring and maintenance are crucial for effective mountain catchments management, particularly in mitigating geo-hydrological risks. Torrent control structures, such as check dams and bed sills, play an important role in stabilising streambeds and reducing the impact of hydrological events such as floods and debris flows. However, their effectiveness depends on proper watershed management supported by systematic monitoring, which must consider sediment dynamic characterizing the catchment. Nowadays, the use of High-Resolution Topography (HRT) data could support torrent control structures monitoring. Light Detection and Ranging (LiDAR) technology has become a standard approach for generating reliable Digital Terrain Models (DTMs) and conducting multi-temporal analyses. When morphometric data derived from DTM are combined with up-to-date inventories of torrent control structures, they offer valuable insights into the condition and functionality of these structures. This study aims to develop and implement an index to identify torrent control structures in the most critical condition at a regional scale, with validation conducted at basin scale. The primary study areas are But (324 km²) and Fella (703 km²) catchments in the Friuli Venezia Giulia region (Italy) on the border with Slovenia and Austria. The methodology integrates HRT-derived data with information from the regional inventory of torrent control structures. The developed index considers characteristics of the structures, such as height and year of construction, alongside sitespecific factors like geology and morphometric parameters derived from DTMs. The results show how this type of analysis can prioritize maintenance interventions and enhance the management of torrent control structures.