River morphological evolution in earthquake-hit region: Effects of floods and pulsed sediment supply

C. G. An, X. D. Fu, G. Parker

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

In mountainous areas, fluvial rivers can reach mobile-bed equilibrium under alternating flood and base flow. However, a massive earthquake as well as subsequent landslides and debris flows can deliver huge amounts of sediment into river channels, driving a river far from its earlier equilibrium state and leaving it to gradually recover through a succession of floods and base flows afterwards. In this paper, we explore a river's mobile-bed equilibrium and its response to increased pulse sediment supply subsequent to a violent earthquake. In order to obtain a first but credible analysis, the simulated gravelbed river was simplified to a rectangular channel with abundant erodible sediment, and a one-dimensional numerical model was implemented for simulation. The results show a hydrograph boundary layer in the mobile-bed equilibrium under the condition of cyclic hydrograph and sediment supply. The river bed responds rapidly after the disruption of the equilibrium but recovers slowly as the disruption disappears. The adjustment of river morphology near the entrance exhibits a nearly exponentially decay rate, which justifies the applicability of a geomorphic rate law. However, the decaying rate for the local bed slope has been found to differ remarkably between the aggradation and degradation stages. This might challenge the conventional use of the rate law, and thus needs to be explored in detail.

Original languageEnglish (US)
Title of host publicationProceedings of the International Conference on Fluvial Hydraulics, RIVER FLOW 2014
PublisherCRC Press/Balkema
Pages1275-1281
Number of pages7
ISBN (Print)9781138026742
StatePublished - Jan 1 2014
Event7th International Conference on Fluvial Hydraulics, RIVER FLOW 2014 - Lausanne, Switzerland
Duration: Sep 3 2014Sep 5 2014

Publication series

NameProceedings of the International Conference on Fluvial Hydraulics, RIVER FLOW 2014

Other

Other7th International Conference on Fluvial Hydraulics, RIVER FLOW 2014
CountrySwitzerland
CityLausanne
Period9/3/149/5/14

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ASJC Scopus subject areas

  • Nature and Landscape Conservation
  • Water Science and Technology

Cite this

An, C. G., Fu, X. D., & Parker, G. (2014). River morphological evolution in earthquake-hit region: Effects of floods and pulsed sediment supply. In Proceedings of the International Conference on Fluvial Hydraulics, RIVER FLOW 2014 (pp. 1275-1281). (Proceedings of the International Conference on Fluvial Hydraulics, RIVER FLOW 2014). CRC Press/Balkema.