Monday, 17 November 2003
Burn Severity Assessment using Differenced Normalized Burn Ratio and Composite Burn Index
Burn Severity of the Hoover Fire (2001) in Yosemite National Park was conducted using Differenced Normalized Burn Ratio (DNBR) and Composite Burn Index (CBI) methods. EROS USGS developed DNBR data from pre- and post-fire Landsat TM images. Yosemite Fire Effects Crew performed burn severity validation the field using CBI methods. CBI is an ocular measure of burn severity for each strata of the vegetative community and provides a scaled value of the magnitude of change from pre-fire conditions. Guided by the DNBR data classified into four severities (low, moderate-low, moderate-high, high), 63 plots were sampled inside the burn perimeter. Correlation between DNBR and CBI values was high enough to continue pursuing this method of developing burn severity data for future and historical fires. Lessons learned include problems with CBI methods due to different burn severity patterns found in the Sierra Nevada.