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Keywords:

  • Alluvial plains;
  • Historical change;
  • Methodology;
  • Ecological successions

Abstract

The hydrosystem of the Rhǒne River, France, is considered in 3 dimensions: the upstream-downstream progression, the transversal dimension (main stream, side-arms, marshes, flood plain and their interconnections), and the vertical dimension (relationships between epigean and ground waters). Emphasis is placed on the temporal dimension, which considers changes in the river's dynamics, and on the development of its ecosystems over several centuries.

Analyses were performed on different spatial scales; the definitions of functional sectors, functional sets and functional units are based on a combination of geomorphic patterns, fluvial dynamics and ecological processes. Synchronic and diachronic analyses were carried out using functional describers (granulometry and organic content of sediments, floral and faunal communities).

These studies deal mainly with the distrubed hydrosystems of regulated rivers. The changes of the ecological successions are focused on after reference to natural models and the reconstitution of ancient human disturbances. Predictive scenarios are proposed to promote ecological management of the alluvial plains in the event of hydroelectric development.