Hydrosedimentary classification of natural and engineered backwaters of a large river, the lower Rhône: possible applications for the maintenance of high fish biodiversity
✍ Scribed by Nicolas, Yann ;Pont, Didier
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 283 KB
- Volume
- 13
- Category
- Article
- ISSN
- 0886-9375
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✦ Synopsis
At the end of the last century, the shorelines of the Lower River Rho Ãne were embanked and submersible dikes were built in the main channel, delimiting dike ®elds. We compared the morphological, hydrological and sedimentary variables of nine dike ®elds, four sites in dead arms and one in the main channel, in order to describe the ¯uviosedimentary functioning and to produce a classi®cation of these different natural and engineered backwaters. Within these `arti®cial ¯oodplains', the different types of backwaters and their long-term changes bear a strong similarity to those observed within a natural ¯oodplain. The long-term frequency of submersion by the water of the main river channel is the ®rst factor that controls the erosion and sedimentation within the different backwaters. Three types of site can be distinguished: the lotic sites are the main channel and one dike ®eld, ®ve dike ®elds comprise the semi-lotic sites and the cluster lentic sites include the three remaining dike ®elds and the four dead arms sites. These three groups also differ in their riparian habitats and in their juvenile ®sh assemblages. As juvenile ®sh were most abundant in the semi-lotic dike ®elds, the use of such structures can be envisaged in order to restore high ®sh diversity in rivers where the former ¯oodplain has disappeared or is no longer accessible to ®sh because of human modi®cations.