If incision is proceeding at unprecedented rates, then the following procedures are recommended in order to asses the impact of this hazard. Determine both the failure susceptibility of the colluvial wedges and the erosion susceptibility of the materials once deposited in the channel, again relative to rainfall events of varying intensities and durations. This information could then be incorporated into the model for debris flow described above to determine flow rates and volumes within the channel and at the canyon mouths. Some possibility exists that the removal of the vegetation by the fire may result in the destabilization of the old landslide deposits. Examination of the aerial photographs indicates that a few steep drainages are superimposed on the lower reaches of the landslide deposits.
Some drainage continues from the landslide deposits down into the heads of the canyons.
If accelerated erosion in a very intense and long duration storm or storms should occur, the headwalls of these canyons could continue to retreat upslope, leading to the destabilization of the landslide mass by removal of downslope support. In addition, if the conditions of increased surface flow, brought about by the removal of vegetation, were to result in the formation of numerous very deep gullies into the surface of the landslide deposits, the breakup of the landslide mass and its eventual destabilization by removal of lateral support might occur. It is unlikely that the entire mass of the landslide deposits would be destabilized at once, and the time frame and rainfall conditions under which this process would occur are unknown. It is further not known if such a destabilization would result in the mobilization of the material into debris flows, or as translational failure of the smaller, broken up blocks. And again, it is not known how much material from such a failure would reach the canyon mouths.