1. Part 6 DEBRIS FLOW HAZARD MAPS

2. USGS landslide hazard maps typically assess debris flows and deeper- seated landslides. Landslide hazard maps for Contra Costa County, CA Debris Flow Hazard Map Landslide Hazard Map

3. The Dec 31, 1933-Jan 1, 1934 Montrose-LaCresenta debris flows damaged or destroyed 600 homes and killed 44. 600,000 cubic yards of material was deposited on the fan in one evening.

4. Left: DRG overlay of 1934 Montrose-LaCresenta debris flows, which occurred several weeks after a series of brush fires in the watersheds at upper right. This is known as a fire-flood sequence.Left: DRG overlay of 1934 Montrose-LaCresenta debris flows, which occurred several weeks after a series of brush fires in the watersheds at upper right. This is known as a fire-flood sequence. Right: DEM overlay of same map. Note flow paths along streetsRight: DEM overlay of same map. Note flow paths along streets

5. Flow quantities generated using 3X bulking factor with Q 100 flow using HEC-RAS; then overlain on digital topo base using ArcGIS. Project-specific Debris Flow Hazard Map