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Picture of depositional zone along the path of the roaring river

Depositional zone along the path of the 1982 flood along the Roaring River.

(Photo by E. Wohl)

Debris Flows - Glaciated Unconfined Channels

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

Debris flow deposition is less likely to reach the main channel due to lack of geomorphic connectivity between the channel and adjacent hillslopes.

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).

Debris flows will not contribute as much sediment to the channel as in confined sections, but the woody debris and sediment deposited in the channel may be retained longer than in unglaciated reaches.

Floods - Glaciated Unconfined Channels

(Information compiled by Liz Gilliam)

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

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

The lack of valley confinement will allow concentrated flow to dissipate, sediments to deposit, and a dampening of the flood wave.

Photo of breached fill dam along lawn lake

Breached fill dam at Lawn Lake in Rocky Mountain National Park following 1982 seepage failure.

(Photo by U.S. Geological Survey)

 

 

 


Click a link below to learn about disturbance regimes in each process domain:

Colluvial Hollows Ephemeral Channels Glaciated Confined Glaciated Partially Confined Glaciated Unconfined Unglaciated Confined Unglaciated Partially Confined Unglaciated Unconfined
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