Effects of cross-sectional geometry, vegetation and ice on flow resistance and conveyance of natural rivers

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en
dc.contributor.author Helmiö, Terhi
dc.date.accessioned 2012-02-13T12:47:35Z
dc.date.available 2012-02-13T12:47:35Z
dc.date.issued 2004-06-18
dc.identifier.isbn 951-22-7072-2
dc.identifier.issn 1456-2596
dc.identifier.uri https://aaltodoc.aalto.fi/handle/123456789/2423
dc.description.abstract The accurate estimation of local hydraulics, i.e. local flow velocities and water depths, is necessary for the restoration and protection of biodiversity. The aim of the thesis was to develop methods and models for designing and evaluating the hydraulic aspects of restoration, rehabilitation and environmental flood management in running waters. Methods for the estimation of flow resistance in natural complex rivers and channels that have composite flow resistance and/or a compound channel shape were tested, and an unsteady 1D flow model for partially vegetated channels with complex geometry was developed. These methods were used to quantify different factors causing flow resistance, e.g. cross-sectional geometry, vegetation, ice cover and momentum transfer, in lowland rivers of different shapes and sizes. The relationship between the flow resistance and the cross-sectional geometry was analysed. Traditional methods used to estimate composite friction factors were found to be accurate in simple concave channels with simple hydraulic properties, but an adjustment of the methods would be necessary for reaches with significant head losses due to lateral momentum transfer. It was seen that the effect of the momentum exchange process between the main channel and the floodplain or streambank vegetation was significant. A procedure for applying the success criteria in a post-project evaluation of local hydraulics was developed, based on the hypothesis of flow resistance and cross-sectional geometry determining local hydraulic conditions in boreal streams. Based on the results from the proposed flow model, the restoration of flood retention areas and local hydraulics is a vital component of the restoration of catchment-scale hydrology, but not sufficient by itself to restore flood peaks to their earlier state, because the changes in land use have often been drastic. en
dc.format.extent 56, [83]
dc.format.mimetype application/pdf
dc.language.iso en en
dc.publisher Helsinki University of Technology en
dc.publisher Teknillinen korkeakoulu fi
dc.relation.ispartofseries Helsinki University of Technology Water Resources publications en
dc.relation.ispartofseries Teknillisen korkeakoulun vesitalouden ja vesirakennuksen julkaisuja fi
dc.relation.ispartofseries 11 en
dc.relation.haspart Helmiö T., 2001. Friction measurements of ice cover: theory and practise in River Päntäneenjoki. In: Proceedings of the 2nd IAHR Symposium on River, Coastal and Estuarine Morphodynamics. Obihiro, Japan, 10-14 September 2001, pages 179-187. [article1.pdf] © 2001 International Association of Hydraulic Engineering and Research (IAHR). By permission.
dc.relation.haspart Helmiö T. and Järvelä J., 2004. Hydraulic aspects of environmental flood management in boreal conditions. Boreal Environment Research 9, in press. [article2.pdf] © 2004 Boreal Environment Research. By permission.
dc.relation.haspart Järvelä J. and Helmiö T., 2004. Hydraulic considerations in restoring boreal streams. Nordic Hydrology 35, number 3, in press. [article3.pdf] © 2004 by authors and © 2004 IWA Publishing. By permission.
dc.relation.haspart Helmiö T., 2004. Hydraulic geometry of cohesive lowland rivers. Boreal Environment Research 9, in press. [article4.pdf] © 2004 Boreal Environment Research. By permission.
dc.relation.haspart Helmiö T., 2002. Unsteady 1D flow model of compound channel with vegetated floodplains. Journal of Hydrology 269, numbers 1-2, pages 89-99. [article5.pdf] © 2002 Elsevier Science. By permission.
dc.relation.haspart Helmiö T., 2004. Unsteady 1D flow model of a river with partly vegetated floodplains – application to the Rhine River. Environmental Modelling & Software, in press. [article6.pdf] © 2004 Elsevier Science. By permission.
dc.relation.haspart Helmiö T., 2004. Flow resistance due to lateral momentum transfer in partially vegetated rivers. Water Resources Research 40, in press. [article7.pdf] © 2004 American Geophysical Union (AGU). By permission.
dc.subject.other Environmental science en
dc.title Effects of cross-sectional geometry, vegetation and ice on flow resistance and conveyance of natural rivers en
dc.type G5 Artikkeliväitöskirja fi
dc.description.version reviewed en
dc.contributor.department Department of Civil and Environmental Engineering en
dc.contributor.department Rakennus- ja ympäristötekniikan osasto fi
dc.subject.keyword hydraulics en
dc.subject.keyword river en
dc.subject.keyword flow resistance en
dc.subject.keyword vegetation en
dc.subject.keyword geometry en
dc.subject.keyword ice en
dc.identifier.urn urn:nbn:fi:tkk-003684
dc.type.dcmitype text en
dc.type.ontasot Väitöskirja (artikkeli) fi
dc.type.ontasot Doctoral dissertation (article-based) en
dc.contributor.lab Laboratory of Water Resources en
dc.contributor.lab Vesitalouden ja vesirakennuksen laboratorio fi

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