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Census and typology of braided rivers in the French Alps
journal contribution
posted on 2017-02-03, 09:23 authored by Herve Piegay, Adrien Alber, Louise Slater, Laurent BourdinFollowing the implementation of the European
Water Framework Directive (WFD) and the need to reach a “good ecological status” for rivers,key-questions are being raised about braided rivers. Before any environmental policy can be drawn up, these rivers need to be located, long term changes must be evaluated, and the regional diversity of such
systems must be understood, as their inner complexity has not yet been well studied. Therefore, the aim of this work is to carry out a census of the braided channels of the French Alps and to establish a typology based on basic geomorphic indicators. A minimum estimate of the cumulative length of braided
rivers prior to major infrastructure construction amounted to 1214 km. Around 53% of these rivers have disappeared during the last two centuries in relation to embankment or channelization, but a loss of 17% is still unexplained. The range in catchment size, mean slope and active channel width has been
determined for the Western Alpine braided channels as well as the range in changes due to narrowing, widening and shifting. Seven types of braided rivers have been distinguished based on geographical
settings (climate conditions and geology) and differences in terms of adjustment to human pressure on peak flow and sediment delivery. The percentage area of islands in the active channel and the relative length of banks also show a regional difference. Maximum and minimum thresholds of braided activity have been established taking into account
the active channel width and the catchment area. The position of the studied reaches between these two thresholds are discussed in relation to position of rivers known in the literature, considering both long term trends and short-term fluctuations in channel width.
History
School
- Social Sciences
Department
- Geography and Environment
Published in
Aquatic SciencesVolume
71Issue
3Pages
371 - 388Citation
PIEGAY, H. ...et al., 2009. Census and typology of braided rivers in the French Alps. Aquatic Sciences, 71(3), pp. 371-388.Publisher
© Birkhauser VerlagVersion
- VoR (Version of Record)
Publisher statement
This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/Publication date
2009Notes
This paper is in closed access.ISSN
1015-1621eISSN
1420-9055Publisher version
Language
- en