Evaluating post-wildfire impacts to Flood Risk Management (FRM) : Las Conchas Wildfire – New Mexico

Abstract

Regional Sediment Management Technical Note (RSM-TN) discusses the impacts of wildfires on USACE Flood Risk Management (FRM) and provides information to evaluate post-fire impacts to USACE missions. The effort was conducted in partnership with the USACE Albuquerque District and was funded through the National RSM and the Flood and Coastal Storm Damage Reduction Research, Development, and Technology Program(s) to understand the impacts of the Las Conchas wildfire on USACE FRM by highlighting the post-fire impacts to the Middle Rio Grande River and Cochiti Reservoir in north-central New Mexico and by presenting approaches to quantify impacts to the USACE mission. BACKGROUND: The 2011 Las Conchas Wildfire burned more than 600 square kilometers (km²) of forested land in the Jemez Mountains (Figure 1), in north central New Mexico. Burn severity was greatest in the mountainous headwaters of some 15 streams that drain directly to the Rio Grande and into the USACE Cochiti Lake (see Figure 1). Since the wildfire, the affected basins have shed sediment at rates far above their historic quantities (Tillery et al. 2012). Based on previous similar events (Cannon et al. 2008), recovery of these watersheds is decades away, creating an ongoing sediment management challenge at Cochiti Lake.