LiDAR Assessment of Sediment Transport Related to the Removal of the Marmot Dam, Sandy River, Oregon

 
Carl Daniel Matzek
January 2013

Abstract

Four Aerial LiDAR survey were used to examine the impacts of the 2007 removal of the Marmot Dam on the Sandy River, Oregon. Geomorphic Change Detection software was used to answer three project goals: 1) to investigate how the dam removal affected sediment distribution in the lower reach of the river, several km downstream of the dam, 2) to determine whether the pulse of sediment from the dam removal created a detectable, successive downstream accumulation of sediment through time, and 3) to assess the effect of natural high-flow events on the sediment distribution related to the dam removal. The results showed that a sediment pulse could be identified and tracked up to 13 km downstream from the former dam, but below that the pulse could not be detected from normal river processes. A majority of the sediment deposited from the dam release moved downstream as a result of high-flow events during winter months.

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