Disturbance Regime in Glaciated Partially Confined Channels

Picture of depositional zone in Roaring River

Depositional zone along the 1982 flood route, Roaring River.

(Photo by U.S. Geological Survey)

Debris Flows - Glaciated Partially Confined Channels

The lack of concentrated rainfall in the glaciated zones reduces the susceptibility of debris flows in the Front Range compared with unglaciated zones.

Debris flow deposition is likely to reach the main channel due to the geomorphic connection of the channel to the hillslopes.

Debris flows may contribute significantly to the wood and sediment of a channel.

In small basins above 2300 m (7,500 ft), many large floods that were attributed to intense rainfall may be debris flows and not water floods (Costa and Jarrett 1981).

Floods - Glaciated Partially Confined Channels

(Information compiled by Liz Gilliam)

The lower elevation of the glaciated zone in Colorado corresponds to the elevation separating rainfall- and snowmelt- dominated hydrographs.

Floods are rare in the glaciated areas of the Front Range because they lie above the 2,300 m line.

Less flood attenuation will occur in the partially confined sections of channel as compared to the unconfined sections, which could cause more scour and change in channel morphology.

Roads are often built directly adjacent to the channel, limiting any lateral migration and flood attenuation.

Picture of debris flow deposits following