Channel change as a response to reforestation and population decline in the rural Toulourenc basin, southern French Prealps
Abstract
As a result of demographic changes, forest cover in the southern French Prealp mountains has increased dramatically during the 20th century. Over the same time period stream morphology within these sub-Mediterranean mountain basins has also changed. At two mainstem locations and eight upstream tributary sites within the Toulourenc basin (~150 km2), we investigated the relationship between hillslope erosion processes and the evolution of stream channel morphology through analysis of historic cadastral maps (circa 1850), aerial photographs (1950-current), topographic surveys (2009-2011), dendrochronolgy of vegetative establishment on abandoned terraces, and bed material size distribution. We observed narrowing of the active channel width, channel degradation, and pavement development along the Toulourenc mainstem and upstream tributaries. On the mainstem Toulourenc, the active channel has narrowed approximately 50% (30m) between 1950 and 2011. As with other studies within the southern French Prealps, the channel modifications appear to be induced by a decrease in the coarse sediment supply as agricultural and logging lands were reforested between 1890 and 1945.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFMEP31D0843R
- Keywords:
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- 1825 HYDROLOGY / Geomorphology: fluvial;
- 1826 HYDROLOGY / Geomorphology: hillslope;
- 1862 HYDROLOGY / Sediment transport;
- 1879 HYDROLOGY / Watershed