Causes of 20th century channel narrowing in mountain and piedmont rivers of southeastern France

摘要: Extensive channel narrowing in southeastern France provides an illustration of geomorphic response to land-use changes. The study region comprises a range environments, from large piedmont and intramountain gravel-bed rivers, small mountain streams. Field measurements analysis historical data demonstrate two distinct periods change. From 1850 1950, is interpreted be the result recovery process widespread destabilization induced by major floods during second half 19th century. At time, largely deforested basins were highly responsive flooding, whereas was accelerated floodplain basin-scale land use changes (afforestation) torrential control works, which turn reduced sediment delivery enabled vegetation development channels. 1950 1970, most studied rivers. This recent phenomenon considered as human-induced fluvial adjustment, directly related forest on river margins human abandonment intensive uses. same long-profile degradation occurred long-term bedload supply decrease. In streams, mainly explained incision seems progress upstream where sources are progressively stabilized afforestation. Copyright © 2002 John Wiley & Sons, Ltd.