Critical flows in semi‐alluvial channels during extraordinarily high discharges: Implications for flood risk management

Abstract For channelized, flood‐regulated rivers, morphological changes are avoided as much as possible. Extraordinarily high flows in the past, however, have demonstrated that channelized rivers may also become morphologically active, especially when a discharge exceeds the design discharge, such a...

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Autores principales:	Christoph Hauer, Peter Flödl, Helmut Habersack, Ulrich Pulg
Formato:	article
Lenguaje:	EN
Publicado:	Wiley 2021
Materias:	channel adjustment flood mitigation hazard analysis river basin management River protective works. Regulation. Flood control TC530-537 Disasters and engineering TA495
Acceso en línea:	https://doaj.org/article/ae6fc75f88d442bfa40069e7f828108c
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spelling	oai:doaj.org-article:ae6fc75f88d442bfa40069e7f828108c2021-11-11T05:32:09ZCritical flows in semi‐alluvial channels during extraordinarily high discharges: Implications for flood risk management1753-318X10.1111/jfr3.12741https://doaj.org/article/ae6fc75f88d442bfa40069e7f828108c2021-12-01T00:00:00Zhttps://doi.org/10.1111/jfr3.12741https://doaj.org/toc/1753-318XAbstract For channelized, flood‐regulated rivers, morphological changes are avoided as much as possible. Extraordinarily high flows in the past, however, have demonstrated that channelized rivers may also become morphologically active, especially when a discharge exceeds the design discharge, such as in hundred‐year floods. However, the morphodynamic potentials and critical flows in such cases have hardly been investigated, and the flood risk to human settlements is therefore poorly understood. The present study aims to analyse the critical flow conditions in Flåmselva, western Norway and the consequences of morphological adjustment on the Froude number from an extraordinary flood event in 2014. Based on a step‐backwater modelling approach, three different high‐resolution river bathymetries of Flåmselva were investigated: (i) pre‐flood, (ii) post‐flood and (iii) re‐channelized morphology. The results showed that due to the 2014 flood, large parts that were in critical flow conditions in the pre‐flood stage (>1), exhibited significantly lower Froude numbers in the post‐flood stage. It turned out that the artificially created plane‐bed morphologies in flood‐regulated channelized rivers can act as drivers for critical flow conditions and that structural as well as non‐structural measures should consider non‐fluvial, semi‐fluvial and fluvial sediment deposits in rivers and floodplains in terms of flood risk management.Christoph HauerPeter FlödlHelmut HabersackUlrich PulgWileyarticlechannel adjustmentflood mitigationhazard analysisriver basin managementRiver protective works. Regulation. Flood controlTC530-537Disasters and engineeringTA495ENJournal of Flood Risk Management, Vol 14, Iss 4, Pp n/a-n/a (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	channel adjustment flood mitigation hazard analysis river basin management River protective works. Regulation. Flood control TC530-537 Disasters and engineering TA495
spellingShingle	channel adjustment flood mitigation hazard analysis river basin management River protective works. Regulation. Flood control TC530-537 Disasters and engineering TA495 Christoph Hauer Peter Flödl Helmut Habersack Ulrich Pulg Critical flows in semi‐alluvial channels during extraordinarily high discharges: Implications for flood risk management
description	Abstract For channelized, flood‐regulated rivers, morphological changes are avoided as much as possible. Extraordinarily high flows in the past, however, have demonstrated that channelized rivers may also become morphologically active, especially when a discharge exceeds the design discharge, such as in hundred‐year floods. However, the morphodynamic potentials and critical flows in such cases have hardly been investigated, and the flood risk to human settlements is therefore poorly understood. The present study aims to analyse the critical flow conditions in Flåmselva, western Norway and the consequences of morphological adjustment on the Froude number from an extraordinary flood event in 2014. Based on a step‐backwater modelling approach, three different high‐resolution river bathymetries of Flåmselva were investigated: (i) pre‐flood, (ii) post‐flood and (iii) re‐channelized morphology. The results showed that due to the 2014 flood, large parts that were in critical flow conditions in the pre‐flood stage (>1), exhibited significantly lower Froude numbers in the post‐flood stage. It turned out that the artificially created plane‐bed morphologies in flood‐regulated channelized rivers can act as drivers for critical flow conditions and that structural as well as non‐structural measures should consider non‐fluvial, semi‐fluvial and fluvial sediment deposits in rivers and floodplains in terms of flood risk management.
format	article
author	Christoph Hauer Peter Flödl Helmut Habersack Ulrich Pulg
author_facet	Christoph Hauer Peter Flödl Helmut Habersack Ulrich Pulg
author_sort	Christoph Hauer
title	Critical flows in semi‐alluvial channels during extraordinarily high discharges: Implications for flood risk management
title_short	Critical flows in semi‐alluvial channels during extraordinarily high discharges: Implications for flood risk management
title_full	Critical flows in semi‐alluvial channels during extraordinarily high discharges: Implications for flood risk management
title_fullStr	Critical flows in semi‐alluvial channels during extraordinarily high discharges: Implications for flood risk management
title_full_unstemmed	Critical flows in semi‐alluvial channels during extraordinarily high discharges: Implications for flood risk management
title_sort	critical flows in semi‐alluvial channels during extraordinarily high discharges: implications for flood risk management
publisher	Wiley
publishDate	2021
url	https://doaj.org/article/ae6fc75f88d442bfa40069e7f828108c
work_keys_str_mv	AT christophhauer criticalflowsinsemialluvialchannelsduringextraordinarilyhighdischargesimplicationsforfloodriskmanagement AT peterflodl criticalflowsinsemialluvialchannelsduringextraordinarilyhighdischargesimplicationsforfloodriskmanagement AT helmuthabersack criticalflowsinsemialluvialchannelsduringextraordinarilyhighdischargesimplicationsforfloodriskmanagement AT ulrichpulg criticalflowsinsemialluvialchannelsduringextraordinarilyhighdischargesimplicationsforfloodriskmanagement
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Critical flows in semi‐alluvial channels during extraordinarily high discharges: Implications for flood risk management

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