The effectiveness of channel control works: how multi-temporal sediment dynamics analysis could support watershed management

Sustainable and effective planning of the channel control works has become an essential tool to manage the hydro-geomorphic risk in mountain basins. However, quite often, there is a lack of information on the efficiency and effectiveness of existing structures and a priori in-depth studies analysing the interaction between sediment morphology dynamics and the possible new channel control works. Nowadays, thanks to multi-temporal (4D) High-Resolution Topography (HRT) surveys, it is possible to derive accurate 4D Digital Terrain Models (DTMs), and reliable DTMs of Difference (DoDs) that greatly simplify the analysis of geomorphological changes and enables the development of innovative approaches to monitor sediment morphology dynamics and the interaction with channel control works. This research aims at introducing and applying a methodological approach. It is based on integrating sediment morphology dynamics data over large time spans in various mountain catchments with an updated, quick, and user-friendly efficiency index for the existing channel control works. The results show how the information provided by sediment morphology dynamics coupled with an updated state of efficiency of existing interventions, could help to support the development of watershed management strategies, assess afterwards the effectiveness of existing structures, and foster a more complete decision-making chain. In the basins analysed, several real examples of the proposed methodology emphasized the usefulness of providing more complete information on the ongoing phenomena, than in the past, by exploiting field surveys and remote sensing data. The realized database could provide numerical data for prediction models of the life-cycle of channel control works or be a starting point for further analysis. Furthermore, the proposed workflow could provide increasingly up-to-date information. This would allow the constant identification of the areas most prone to hazards, support effective risk management decisions, direct maintenance works and find more appropriate solutions.