Preprints
https://doi.org/10.5194/esurf-2020-67
https://doi.org/10.5194/esurf-2020-67

  08 Sep 2020

08 Sep 2020

Review status: a revised version of this preprint is currently under review for the journal ESurf.

Effect of stress history on sediment transport and channel adjustment in graded gravel-bed rivers

Chenge An1,2, Marwan A. Hassan2, Carles Ferrer-Boix3, and Xudong Fu1 Chenge An et al.
  • 1Department of Hydraulic Engineering, State Key Laboratory of Hydroscience and Engineering, Tsinghua University, Beijing, China
  • 2Department of Geography, The University of British Columbia, Vancouver, BC, Canada
  • 3Department of Civil and Environmental Engineering, Technical University of Catalonia, Barcelona, Spain

Abstract. With the increasing attention on environmental flow management for the maintenance of habitat diversity and ecosystem health of mountain gravel-bed rivers, much interest has been paid to how inter-flood low flow can affect gravel-bed river morphodynamics during subsequent flood events. Previous research has found that antecedent conditioning flow can lead to an increase in the critical shear stress and a reduction in sediment transport rate during a subsequent flood. But how long this effect can last during the flood event has not been fully discussed. In this paper, a series of flume experiments with various durations of conditioning flow are presented to study this problem. Results show that channel morphology adjusts significantly within the first 15 minutes of the conditioning flow, but becomes rather stable during the remainder of the conditioning flow. The implementation of conditioning flow can indeed lead to a reduction of sediment transport rate during the subsequent hydrograph, but such effect is limited only within a relatively short time at the beginning of the hydrograph. This indicates that bed reorganization during the conditioning phase, which induce the stress history effect, is likely to be erased with increasing intensity of flow and sediment transport during the subsequent flood event.

Chenge An et al.

 
Status: final response (author comments only)
Status: final response (author comments only)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

Chenge An et al.

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Short summary
Mountain rivers are characterized by large fluctuations of water flow, including both flood and inter-flood low flow. Recently, increasing attention has been paid on how inter-flood low flow affects the sediment transport in subsequent flood. Here we present a series of flume experiments. Results show that the existence of inter-flood low flow can reduce the sediment transport at the beginning of the subsequent flood. However, such effect is gradually erased with the increase of flow intensity.