As the Horseshoe 2 fire is slowly contained in southern Arizona, residents are starting to prepare for post-fire flooding and debris flows.
Coincidentally, AZGS today published a report on the post-fire sediment movement in the Flagstaff area that resulted from last year's Schultz fire. The lessons learned there have relevance to the threats facing us from this summers monsoon rains:
The 2010 Schultz Fire burned 6,091 hectares (15,051 acres) of Ponderosa Pine and mixed conifer forest, four kilometers (two and a half miles) north of Flagstaff, Arizona between June 20 and 30, 2010. Sixty-seven percent of the affected area burned at moderate to high intensity, destroying much of the vegetation and organic duff layer that previously covered the forest floor. The intensity of the fire, granular soils, and steep slopes made the burn area highly susceptible to the generation of debris flows and hyperconcentrated flows by runoff from intense summer monsoon storms common in the area."Movement of channel-borne sediments in the 2010 Schultz fire burn area," 2011, by M. D. Carroll, AZGS Contributed Report CR-11-A