Control works and soil conservation techniques for watershed management and forest protection: effect evaluation and novel design criteria
Structures and techniques aiming at controlling sediment transport-related or erosion-related issues are numerous and sometimes very old. Hillslope management and bioengineering, reforestation, and torrent control works using transverse structures, as check dams and more recently open check dams, are common all over the world to curtail soil erosion and torrential hazards. These actions may be launched for the control of sediment supply (i) to the stream fans and valley rivers for flood protection, (ii) to dam reservoirs for water storage, and basically, (iii) for the mere mountain soil conservation and agriculture protection. The profound objectives of each action are diverse and vary depending on the geomorphic context and local state of the sediment cascade, where the implementation takes place. The lack of sufficient understanding of soil erosion processes, sediment (dis)connectivity activation and torrential hazards propagation continues to make soil erosion prevention and torrent control complex topics with insufficient implementation criteria and long-term effect assessment methods. Consequently, some projects still experience disappointing results due to many different reasons, such as poor construction quality, inadequate location or lack of adequate design criteria. In addition, these actions induce secondary effects (e.g., block of the downstream transfer of water and sediments), which should be better controlled or possibly prevented. This EGU session aims at gathering the whole community interested in human actions on control works and soil conservation techniques at the waterhed scale. Any contributions to the understanding of soil erosion control and sediment transport management based on detailed field experiences, high-quality laboratory works, validated numerical models and effectiveness assessment methods are welcome. Using the knowledge gaps identified above as a starting point, the proposed EGU session wishes, for the third year, to join and share scientific and technical opinions from all around the world, related to the legacy effects of soil erosion control and (open) check-dam design criteria, highlighting the role of the complex interactions between ecological elements, geomorphic processes and engineering activities.