Slide 11 of 30
Notes:
Finally, in the Grand Canyon of Arizona, deep incision by the Colorado River has resulted in steep tributaries that occasionally suffer large debris flows as a result of the steep canyon relief. These debris flows debauch into the Colorado River (in the background) and produce debris fans with boulders that may be up to 5 m in diameter. This causes rapids in the main river, and most of the elevation loss of the Colorado River in the Grand Canyon occurs in such rapids. As a result, the Colorado Plateau, upstream, has not been as deeply dissected as would have been the case if this locally produced coarse debris were not introduced into the river as a result of its past downcutting. Thus the coarse, locally produced debris acts as a buffer to further incision. Incorporation of such local supply of debris into landscape models will be challenging. The rate and frequency of supply must be accounted for, as well as the grain size distribution of debris, and the abrasion, communution and reworking of the debris my the main channel must also be modeled.
