Accession Number : ADA596264


Title :   Mount St. Helens Project. Cowlitz River Levee Systems, 2009 Level of Flood Protection Update Summary


Corporate Author : ARMY ENGINEER DISTRICT PORTLAND OR


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a596264.pdf


Report Date : 04 Feb 2010


Pagination or Media Count : 272


Abstract : USACE periodically updates the Levels of Protection (LOP) for the Cowlitz River levees as part of ongoing activities of the Mount St. Helens project. The most recent comprehensive LOP update prior to 2009 was performed in 1997 for the Cowlitz River Flood Hazard Study. Since 1997, there have been several interim assessments of the levee system, however a complete study of the hydrology, hydraulics, and levee index points were not performed for these interim assessments. The current (2009) LOP assessment for the Cowlitz River levees incorporates a detailed review of each component of the 1997 Cowlitz River Flood Hazard Study. This update includes: * Revisions to the Fragility Curve for the levees; * Revisions to the Cowlitz River discharge-frequency curve; * Revisions to the stage-discharge relationships based on a comprehensive Cowlitz River survey, performed in August 2009 by David Evans and Associates, from the Toutle River confluence, approximately River Mile (RM) 20, to the Columbia River confluence (RM 0); * Revisions to hydraulic and hydrologic uncertainty.


Descriptors :   *LEVEES , HYDRAULICS , HYDROLOGY , RIVERS , UNCERTAINTY , WASHINGTON(STATE)


Subject Categories : Hydrology, Limnology and Potamology
      Civil Engineering


Distribution Statement : APPROVED FOR PUBLIC RELEASE