Publication Date


Document Type


Degree Name

M.S. (Master of Science)

Legacy Department

Department of Geography


Sediments (Geology)--Oregon--Walla Walla River Watershed; Sediments (Geology)--Washington (State)--Walla Walla River Watershed; Reservoir sedimentation--Oregon--Walla Walla River Watershed; Reservoir sedimentation--Washington (State)--Walla Walla River Watershed


This study examines the impact that the hydroclimate of the Walla Walla Basin has on sediment delivery to a branch of the McNary Reservoir. The reservoir, referred to as Lake Wallula, was formed in April, 1953, with the closure of the McNary Dam on the Columbia River. Sediments eroded from the basin were deposited in the reservoir in subsequent years. The U. S. Army Corps of Engineers performed eight reservoir branch capacity surveys from 1953 to 1965 to determine net deposition of sediment. Basin hydroclimate data that is available for this study include: (1) precipitation, (2) river discharge, and (3) temperature and snowfall data. The objective of this thesis is to assess the impact that the Walla Walla Basin’s seasonal and inter-annual hydroclimate has on sediment delivery to the Walla Walla Branch of Lake Wallula. Specifically, this is done by: (1) identifying the best hydroclimatic indicators of sediment delivery, (2) creating a sediment delivery model, (3) assessing the significance of hydroclimate variability, and (4) performing an event analysis. The topography within the basin presents additional challenges due to the impact o f varying climate conditions at different elevations. The results of this study indicate that it is tHp combination of the hydroclimate elements which make up discharge that determine sediment delivery rates. Most importantly, it is the major events that have the greatest impact on the movement of sediment from the basin. This was most pronounced in the great flood of December, 1964, when the U. S. West Coast experienced the greatest mobilization of sediment this century.


Includes bibliographical references (pages [84]-86)


viii, 90 pages




Northern Illinois University

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