HR: 1330h
AN: H52A-1181    [PDF]
TI: River Channel Cut-off Dynamics, Sacramento River, California, USA
AU: Avery, E R
EM: avery@geology.ucdavis.edu
AF: Department of Geology, University of California, Davis, Davis, CA 95616 United States
AU: * Micheli, E R
EM: micheli@vom.com
AF: Department of Geology, University of California, Davis, Davis, CA 95616 United States
AU: Larsen, E W
EM: ewlarsen@ucdavis.edu
AF: Department of Geology, University of California, Davis, Davis, CA 95616 United States
AB: We measured patterns of channel migration and cut-off on a 200 km reach of the central Sacramento River (ranging from Red Bluff to Colusa) over the last century. The river is a meandering alluvial stream which flows along the eastern margin of the Great Central Valley. River bank locations and channel centerlines were mapped from historic topographic maps (1887 and 1904) and aerial photographs (1920 -1997) and stored in a GIS format. By intersecting sequential channel centerlines, we measured changes in river mobility over time, identified approximate dates and locations of cut-offs, and quantified cut-off meander bend morphology. We identified 38 cutoffs over this period of study and compared geometries of cut-off versus stable bends. While 4-7% of the entire channel length migrated via progressive migration and 2-10% tended to migrate via cut-off per year over this period, we found that the majority of lateral channel change was attributable to cut-off processes alone. We also estimated that cut-off frequency tended to increase up to three-fold over time. Further, by plotting cumulative migration over time against a valley axis coordinate system, we noted that highly mobile reaches tend to be separated by relatively static reaches. Over this time scale, we do not observe the classical pattern of downstream migration of meander trains. We explore potential controls on cut-off location including valley slope and tectonics, tributary location, and mapped channel modifications. By improving our ability to predict the likelihood of meander cut-off, resource managers will be better able to balance habitat restoration with future demands for flood control and water supply
DE: 1824 Geomorphology (1625)
SC: Hydrology [H]
MN: 2003 Fall Meeting