Quantifying the combined effects of multiple extreme floods on river channel geometry and on flood hazards

Guan, Mingfu; Carrivick, Jonathan L.; Wright, Nigel; Sleigh, Andrew; Staines, Kate E. H.

doi:10.1016/j.jhydrol.2016.04.004

Cited by 69 publications

(29 citation statements)

References 36 publications

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“…The striking rearrangements to the channel geometry and configuration highlight the nonsteady nature of the channel morphology when subjected to repeated GLOFs. Thus, not only is the hydrology changing with the episodic release of stored lake water, but additionally, the conveyance system is changing, the latter of which has recently been shown to change the behavior of flood inundation just as much, or even more than, changing hydrology [e.g., Slater et al ., ; Guan et al ., ]. In total, our observations highlight the impacts that the onset of large, frequent flood events can have on the hydrology and geomorphology of an ice‐marginal fluvial system.…”

Section: Discussionmentioning

confidence: 74%

Hydrologic and geomorphic changes resulting from episodic glacial lake outburst floods: Rio Colonia, Patagonia, Chile

Jacquet

McCoy

McGrath

et al. 2017

Geophysical Research Letters

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Glacial lake outburst floods (GLOFs) are a prominent but poorly understood cryospheric hazard in a warming climate. We quantify the hydrologic and geomorphic response to 21 episodic GLOFs that began in April 2008 using multitemporal satellite imagery and field observations. Peak discharge exiting the source lake became progressively muted downstream. At ~40–60 km downstream, where the floods entered and traveled down the main stem Rio Baker, peak discharges were generally < 2000 m3 s−1, although these flows were still >1–2 times the peak annual discharge of this system, Chile's largest river by volume. As such, caution must be applied to empirical relationships relating lake volume to peak discharge, as the latter is dependent on where this observation is made along the flood path. The GLOFs and subsequent periods of free drainage resulted in > 40 m of incision, the net removal of ~25 × 106 m3 of sediment from the source lake basin, and a nonsteady channel configuration downstream. These results demonstrate that GLOFs sourced from low‐order tributaries can produce significant floods on major main stem rivers, in addition to significantly altering sediment dynamics.

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Section: Discussionmentioning

confidence: 74%

Hydrologic and geomorphic changes resulting from episodic glacial lake outburst floods: Rio Colonia, Patagonia, Chile

Jacquet

McCoy

McGrath

et al. 2017

Geophysical Research Letters

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“…However, the rivers themselves and their floodplains change over time [50][51][52][53]. These can be natural and gradual changes in the river morphodynamics and flood regime [54][55][56][57], changes in the adjacent vegetation [58], or disruptive changes by flood events [59], for example by levee failures [60]. Last but not least, anthropogenic interventions are more or less the most relevant driver of flood risk in a floodplain; that is, the construction of flood defenses such as levees and dams [61][62][63] or river restoration projects [64][65][66].…”

Section: Changes In Flood Processesmentioning

confidence: 99%

Floodplains and Complex Adaptive Systems—Perspectives on Connecting the Dots in Flood Risk Assessment with Coupled Component Models

Zischg

2018

Systems

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Floodplains, as seen from the flood risk management perspective, are composed of co-evolving natural and human systems. Both flood processes (that is, the hazard) and the values at risk (that is, settlements and infrastructure built in hazardous areas) are dynamically changing over time and influence each other. These changes influence future risk pathways. The co-evolution of all of these drivers for changes in flood risk could lead to emergent behavior. Hence, complexity theory and systems science can provide a sound theoretical framework for flood risk management in the 21st century. This review aims at providing an entry point for modelers in flood risk research to consider floodplains as complex adaptive systems. For the systems science community, the actual problems and approaches in the flood risk research community are summarized. Finally, an outlook is given on potential future coupled component modeling approaches that aims at bringing together both disciplines.

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“…Building on the depth‐averaged 2‐D flow and sediment transport model in the previous work [ Guan et al ., ], this study further incorporates turbulent terms and dispersion terms representing the effects of a secondary flow. The original hydromorphodynamic model is detailed in Guan et al .…”

Section: Model Developmentmentioning

confidence: 99%

Physical complexity to model morphological changes at a natural channel bend

Guan

Wright

Sleigh

et al. 2016

Water Resources Research

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This study developed a two‐dimensional (2‐D) depth‐averaged model for morphological changes at natural bends by including a secondary flow correction. The model was tested in two laboratory‐scale events. A field study was further adopted to demonstrate the capability of the model in predicting bed deformation at natural bends. Further, a series of scenarios with different setups of sediment‐related parameters were tested to explore the possibility of a 2‐D model to simulate morphological changes at a natural bend, and to investigate how much physical complexity is needed for reliable modeling. The results suggest that a 2‐D depth‐averaged model can reconstruct the hydrodynamic and morphological features at a bend reasonably provided that the model addresses a secondary flow correction, and reasonably parameterize grain‐sizes within a channel in a pragmatic way. The factors, such as sediment transport formula and roughness height, have relatively less significance on the bed change pattern at a bend. The study reveals that the secondary flow effect and grain‐size parameterization should be given a first priority among other parameters when modeling bed deformation at a natural bend using a 2‐D model.

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Quantifying the combined effects of multiple extreme floods on river channel geometry and on flood hazards

Cited by 69 publications

References 36 publications

Hydrologic and geomorphic changes resulting from episodic glacial lake outburst floods: Rio Colonia, Patagonia, Chile

Hydrologic and geomorphic changes resulting from episodic glacial lake outburst floods: Rio Colonia, Patagonia, Chile

Floodplains and Complex Adaptive Systems—Perspectives on Connecting the Dots in Flood Risk Assessment with Coupled Component Models

Physical complexity to model morphological changes at a natural channel bend

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