Nondimensional simulation-based regression formulas for slit dam design in mountain rivers

Compact regression formulas were developed through one-dimensional (1D) unsteady flow numerical model simulations for the analysis of slit dam (SD) hydraulic behavior in torrents. The formulas allow an easy evaluation of the sediment-trapping efficiency and of the depth of the sediment deposit upstream from SDs at the peak time of flood. The use of the developed formulas also provides a first estimation of the dam self-cleaning effects at the end of the event associated with the receding stage of the hydrograph. Compared to the approaches available in the literature, the results of this work allow the extension of the analysis of the trapping processes behind SDs to conditions of unsteady flow. The developed formulas may represent a simple and reliable tool for SD design in mountain gravel bed rivers characterized by relatively steep slopes (1-5%).