Effects of check dams on bed-load transport and steep-slope stream morphodynamics - Institut National de Recherche en Agriculture, Alimentation et Environnement
Effects of check dams on bed-load transport and steep-slope stream morphodynamics
Effets des barrages de correction torrentielle sur le transport par charriage et la morphodynamique des torrents
Abstract : Check dams are transversal structures built acrossmorphologically-active streams inmountainous regions. These structures have been used widely in torrent-hazard mitigation for over 150 years. Thousands of them are regularly maintained by stream managers and torrent-control services. The stabilization role of these structures is well known, i.e. they durably constrain the stream-bed through the creation of vertical and planar fixed points. What is not yet clear is to what extent check dams influence bed-load transport: How do peak solid discharge or flood-transported volume change when check dams are added to a reach? To address these questions, longlasting small-scale experiments were conducted in a 4.8-m-long flume with either one, three or no structures. The results show that the addition of structures creates independent compartments in the bed level, which have a strong influence on bed surface armouring and streammorphodynamics: the consequence is that instantaneous transport intensities are unchanged, but peak solid discharge occur more often and for shorter duration. This results in the same total transported volume over the long term, but reduced volume for a single transport event. It reaffirms the observation of pioneering authors of the mid-19th and early 20th century who conceptualized the possible sediment transport regulation function of check dams: in addition to stabilizing the streambed, check dams influence bed-load transport through a buffering effect, releasing frequently and in small doses what, in their absence, would be transported abruptly en masse during rare extreme events.
keyword : SMALL SCALE MODELS
Keywords : TORRENT CONTROL WORKS
Guillaume Piton, A. Recking. Effects of check dams on bed-load transport and steep-slope stream morphodynamics. Geomorphology, Elsevier, 2017, 291, pp.94-105. ⟨10.1016/j.geomorph.2016.03.001⟩. ⟨hal-02603365⟩