Laurent Astrade

Tree-ring response of Populus tremula L. and Quercus robur L. to recent spring floods of the Saône River, France

The effects of floods on the radial growth of Populus tremula L. and Quercus robur L. in past decades were studied on a forested island in the Saone River (France). The study considered two stands ...

Energy gradient and geomorphological processes along a river influenced by neotectonics (the Saône river, France)

Abstract The purpose of this study is to link the sediment transit and the flood plain storage of the Saone to hydromorphological characteristics of the hydrosystem, which exemplifies a new approach to sediment dynamics. The study of suspended sediment concentration in terms of temporal evolution, together with sediment deposition in terms of spatial variability, is a way to record the longitudinal evolution of the sediment load, which expresses the available energy gradient from upstream to downstream in hydrosystem. The Saone river is a 480-km-long Rhone tributary, with an oceanic pluvial regime, and an average yearly discharge of 440 m s−1 at Lyons. The watercourse is characterised by very gentle slopes controlled by the neotectonics of the Bresse trough and by Holocene fluvial dynamics. Sediments were sampled during the December 1993–January 1994 flood (2 375 m3 s−1) and the 1995 January–February flood (1 826 m3 s−1). A fine partition into homogeneous sectors, using stream power as well as shear stress, has been realized on a 400 km reach using longitudinal and cross-sections at one kilometre intervals. This partition, compared with the results of the field sampling, shows that the amount of energy is closely connected to the hydromorphological characteristics of the river.