River channel cutoff dynamics, Sacramento River, California, USA

• DOI: 10.1002/rra.1360
• Publication Date: 2010-02-23T00:11:59Z
• Authors: E. R. Micheli; E. W. Larsen
• Keywords: Cut-off; Cutoff frequency

Abstract We measured patterns of river channel migration and cutoff between 1904 1997 on a 160 km meandering alluvial reach the Sacramento River by intersecting sequential set centrelines mapped from field survey aerial photography. identified approximate dates locations cutoffs quantified dimensions. Twenty‐seven chute 11 partial occurred over this 93‐year time interval, with an average one approximately every 2.5 years or 0.0029 per kilometre year. The rate lateral change was study period 5.5 ± 0.6 m year −1 (approximately 0.02 widths year) due to progressive combined. An 5% total length moved laterally via at 22.1 3.3 versus 94% that 4.7 0.5 . remaining 1% migrated 13.0 2.8 Although less predominant mode than in terms length, 20% floodplain area successive attributable cutoffs. Peak frequency concentrated temporally 1964 1987 also spatially clustered specific active sub‐reaches along valley axis entire period. hypothesize probability is function both geometry discharge. Bends experienced displayed sinuosity 1.97 0.1, radius curvature 2.1 0.2 entrance angle 111 7°, as opposed values for bends migrating progressively 1.31 0.01, 0.1 66 1°, respectively. experiencing appears have been consistently declining 2.25 0.35 1.54 0.23 1987. trend may be part influence land‐use changes, such conversion riparian forest agriculture, ‘erodibility’ bank materials. For post‐dam flow regime (1937 on), significantly correlated estimate cumulative overbank flow. Copyright © 2010 John Wiley & Sons, Ltd.