Comparing modeling results with other model predictions
The original post-fire erosion analysis was carried out by a Forest
Service Burned Area Emergency Response (BAER) specialist using the
Erosion Risk Management Tool (ERMiT; Robichaud et al., 2007) to quickly
estimate upland erosion following the Emerald Fire (Table 6; Young,
2016). Young (2016) followed recommended methods and only presented
potential erosion from 2-, 5- and 10-year events, as the probability of
a more severe event was unlikely. The three recorded precipitation
events that occurred immediately following the wildfire (81, 56, and 114
mm) were similar to the 5 to 10-year return period range of the ERMiT
predictions for single storms (Table 6), if a rainfall event had been
the cause of ERMiT’s 10-y runoff event rather than rain-on-snow. Thus
Young’s (2016) selection of events was close to what actually occurred.
We estimated a spatially averaged erosion rate of 16-25 Mg
ha-1, depending on hillslope profile for the three
observed storms. The ERMiT predictions for these three storms would be
approximately one 2-y event (0.22 Mg ha-1), one 5-y
event (6.15 Mg ha-1) and one 10-y event (14.76 Mg
ha-1) for a total of about 21 Mg
ha-1. Young’s rapidly completed predictions, with a
stated accuracy of plus or minus 50 percent, are similar to our more
detailed analyses, confirming that the coarse-scale ERMiT predictions
are reasonable for rapid post wildfire erosion analysis. The current
BAER erosion prediction technologies as exemplified by Young (2016),
however, did not consider the effects of roads in his analyses, which we
have shown can be significant.