Multi-scale fire hazard assessment for wildland urban interface areas: An alternative futures approach (California).

摘要

This thesis proposes an “alternative futures” approach to fire hazard assessment for communities adjacent to areas of high wildland fire risk. A case study is presented which applies these techniques to several communities within the San Jacinto Mountains of southern California. The potential impacts of varying levels of public and private fuels management are compared and contrasted using a multiscale simulation modeling approach. Five scenarios are tested relative to current conditions, fuel reduction on all lands, fuel reduction on private parcels only, fuel reduction efforts on public lands only, and fuel accumulation on all lands.; The work is primarily synthetic in that it is designed to help integrate fire planning within broader land use planning methods. Pre-existing, field-validated fire simulation models are used to the greatest extent possible. The fire spread model Farsite is used to predict landscape scale fire behavior. However, in order to address some of the key policy issues of significance to fire planning, a new structural ignition vulnerability model (SiteFire) is proposed. Because urban intermix fires are not subject to direct experimentation, such a model cannot be field validated. The model has, however, been calibrated using post-fire analysis data from other similar fires.; Required fire model parameters were predicted from remote sensing data using classification and regression trees (CART) and extensive ground sampling. In order to visualize model results for both expert and general public audiences, a series of animated visual landscape simulations were produced in which predicted fire behavior was shown in context with shrubs, trees and structures as distinct, identifiable objects.; Within the case study area and stipulated scenario parameters, all fires burned into the communities. Under the best case scenario, the fire caused little damage to structures and would be considered beneficial from an ecological point of view. A fire under the fuel accumulation scenario would cause loss of all structures and kill most all of the trees. In terms of structural damage, the scenario under which fuels reduction occurred only on private lands performed about ten times better than that which relied entirely on public lands fuels reduction.