GSA Connects 2021 in Portland, Oregon

Paper No. 181-7
Presentation Time: 3:25 PM


CHIN, Anne1, BURTON, Jonathan2, GAUTREAU, Tandie E.2, KINOSHITA, Alicia M.3, FLORSHEIM, Joan4 and O'DOWD, Alison P.5, (1)University of Colorado DenverGeography and Environ Sciences, PO Box 173364, Denver, CO 80217-3364, (2)University of Colorado Denver Geography and Environ Sciences, PO Box 173364, Denver, CO 80217-3364, (3)Civil, Construction, and Environmental Engineering, San Diego State University, San Diego, CA 92182, (4)Earth Research Institute, Univeristy of California, Santa Barbara, CA 93106, (5)Department of Environmental Science and Management, Humboldt State University, Arcata, CA 95521

The Waldo Canyon Fire was among the numerous wildfires that occurred during summer of 2012 along the Front Range of Colorado. It burned many watersheds in Pike National Forest near the city of Colorado Springs characterized by step-pool morphology. A long-term study initiated after the Waldo Canyon Fire documented how changes within step-pool channel reaches related to the severity of burn. In the years immediately following the fire, a severely burned channel experienced rapid incision down to bedrock following minor post-fire storms, along with degradation of benthic macroinvertebrates, whereas channels unburned and affected by low-severity burn remained intact even through 500-1000 year major storms. Now, nine years later, this effort examines changes in the impacted channels in conjunction with recovery of the burned vegetation. Analysis of remote imagery showed that vegetation has re-grown, as suggested by reflectance values that have increased to 40% by 2019. Relatively low-magnitude storms have also occurred over these years. Re-surveys of burned channels, however, showed that morphologic recovery has not yet occurred, with the burned channels largely maintaining their post-burn incised character. These preliminary results support the idea that the generation and delivery of post-fire sediment through burned watersheds may take decades or longer to complete, even though the forest and aquatic ecology may recover more quickly. Insights regarding the recovery of river ecosystems from the Waldo Canyon Fire are important, as data beyond the initial few post-fire years are generally lacking to develop models of recovery over longer timeframes, and as wildfires grow in frequency and magnitude under a warming climate.