The impact of different sediment concentrations on river morphological evolution

Yen Yu Chiu*, I. Ling Wu, Sheng Hsueh Yang, Ren Kai Jhong, Tung Chou Hsieh, Keh Chia Yeh

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Suspended sediment concentration is an important factor of river morphological evolution, which has been represented generally via suspended sediment concentration-discharge (SSC-Q) rating curves in research and practices. In this study, we applied a two-dimensional sediment transport model to simulate the changes of riverbed under different discharge hydrographs and different SSC - Q rating curves, which were measured by two different methods (1.Water Resources Agency regularly sampling over the years; 2. Time Domain Reflectometry (TDR) data for an entire flood duration). Erosion and deposition depths and volumes, and net sedimentation depths and volumes of five different flood events were quantified and compared. The results indicated that the difference of sedimentations between high and low SSC is significant in high discharge events. According to the projected distributions of water depths, flow velocities and sedimentations, we speculated that this difference originated from the depositions of high riverbanks when overbank flooding occurs. The hourly changes of riverbed demonstrated the impact of flood peak might partly recover during the recession. In addition, we observed the hysteresis effect in TDR recording. Due to the various impact factors of sediment supply, we recommended that different concentrations should be considered in studies of river morphological evolution, and the yielding sediment mechanisms under different scenarios in watersheds could be analyzed to study the impact on downstream areas.

Original languageEnglish
Pages (from-to)54-65
Number of pages12
JournalTaiwan Water Conservancy
Volume65
Issue number4
StatePublished - 1 Jan 2017

Keywords

  • Sediment transport model
  • Sedimentation
  • Suspended sediment concentration

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