Selecting a Methodology for Delineating Mudslide Hazard Areas for the National Flood Insurance Program

摘要

The mudslide provisions of the National Flood Insurance Program and the problems associated with defining the term 'mudslide' are reviewed. The phenomena that can occur as a result of heavy rain in mountain drainage basins are described. A distinction is made between clear-water floods, mud flows and other landslides. The methodology developed by the Los Angeles County Flood Control District and used to construct maps of mudslide hazard in the San Gabriel Mountains is evaluated and its limitations assessed. The method is found to apply only to mud floods that overflow debris catchment basins in the San Gabriel Mountains, and is deemed unlikely to be applicable to other phenomena in other locations, although the general approach may be applicable in some hydrologically similar areas.