Bedload trapping in open check dam basins - measurements of flow velocities and depositions patterns

In steep slope streams, torrential-hazards mainly result from abrupt and massive sediment deposits. Open check dams are regularly used in natural hazard mitigation to trap sediment and driftwood. A good comprehension of the phenomena that occur in these structures is needed to optimize their design. In this paper, we present new results from small scale experiments addressing (i) a validation of water stage - discharge formula proposed in the literature for slit and slot dams; (ii) recommendations in the use of formula dedicated to deposition-thickness-estimation; (iii) geomorphic and hydraulics descriptions that seek to help field practitioners and numerical modelers to better understand what can be observed in labs and in the field and what kind of phenomena should be modeled. A special attention has been paid to highlight the implication of our results in the use of formula and in structure design and maintenance.