Part 6 DEBRIS FLOW HAZARD MAPS. USGS landslide hazard maps typically assess debris flows and deeper-...
-
date post
19-Dec-2015 -
Category
Documents
-
view
244 -
download
4
Transcript of Part 6 DEBRIS FLOW HAZARD MAPS. USGS landslide hazard maps typically assess debris flows and deeper-...
Part 6Part 6
DEBRIS FLOW DEBRIS FLOW HAZARD MAPSHAZARD MAPS
• 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
• 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.
• Left: DRG overlay of Left: DRG overlay of 1934 Montrose-LaCresenta debris flows1934 Montrose-LaCresenta debris flows, , which occurred several weeks after a series of brush fires in the which occurred several weeks after a series of brush fires in the watersheds at upper right. This is known as a watersheds at upper right. This is known as a fire-flood fire-flood sequence.sequence.
• Right: DEM overlay of same map. Note flow paths along streetsRight: DEM overlay of same map. Note flow paths along streets
Flow quantities generated using 3X bulking factor with Q100 flow using HEC-RAS; then overlain on digital topo base using ArcGIS.
Project-specific Debris Flow Project-specific Debris Flow Hazard MapHazard Map