Dambreak flood impact on mountain stream bedload transport after 13 years

Abstract

Studies of the bedload transport regime of the Roaring River, Colorado, in 1984–88, following a dambreak flood in 1982, showed that bedload transport rates were an order of magnitude higher than under pre-flood conditions. A gorge eroded by the flood in glacial moraine acted as a major sediment supply source. Measurements in early June 1995 showed a continued potential for high sediment supply from the gorge and a bedload transport regime similar to that of 1984–88. A major snowmelt flood in mid-June flushed sediment supplies from the gorge and measurements in July showed a corresponding reduction in bedload transport. However, high sediment supply will continue until the gorge cliffs revegetate or erode to a stable slope. The measurements demonstrate both the control exercised by sediment supply on transport rates and the persistent long-term impact of major floods on mountain streams. © 1998 John Wiley & Sons, Ltd.