Document: NUREG-0800
Document ID: c97c665c-1f0f-4a2d-a4db-4e0dbd99eab3
Document Type: srp
Title: CHANNEL DIVERSIONS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0707/ML070730434.pdf
Revision Date: 2023-06
Chapter: 2
Section ID: 2.4.9
CFR Part: 
CFR Title: 

Content:
ribing historical occurrences of channel diversions in the region is reviewed to determine if additional protection should 2.4.9-7 Revision 3 - March 2007 be considered in the design of safety-related facilities. Publications of the United States Geologic Survey (USGS), the U.S. Army Corps of Engineers (USACE), USACE Engineer Research, National Cooperative Highway Research Program (NCHRP) of the Transportation Research Board, State highway departments and other sources are used to identify the history and potential for channel diversions in the region. For any channel diversion events, historical water-flow variations should be noted, as well as the volume of any blocking materials with respect to the channel geometry. The phrase “channel diversions” is not commonly used in the literature, so the reviewer should also search for “channel migration,” “channel geomorphology,” “physical hydrology,” and initiating events such as “landslides” and “levee breaks” or “breaches.” Channel history and potential for diversions is reviewed for the following three areas: A. Upstream, and generally above-bank, due to geologic, seismic, or topographic change, e.g., caused by hillslope failure or earthquakes B. Upstream (or downstream) and within the bank, and due to erosion, deposition or channel migration, e.g., loss of a revetment, or alluvial channel meander changes C. Upstream (or downstream) and within the bank and due to thermal causes such as ice-jams. 2. Regional Topographic Evidence: Regional topographic evidence which suggests that future channel diversion may or may not occur is used in conjunction with evidence of historical diversions. The reviewer studies elevation relief of topographic maps along with geologic maps to qualitatively determine candidate locations where geologic or human-induced events increase the likelihood of channel diversions. Evaluate the channel geographic layout (meanders), cross-section (width and depth), profile