Cumulative Effective Stream Power and Bank Erosion on the Sacramento River, California, Usa

Abstract

Bank erosion along a river channel determines the pattern of channel migration. Lateral channel migration in large alluvial rivers creates new floodplain land that is essential for riparian vegetation to get established. Migration also erodes existing riparian, agricultural, and urban lands, sometimes damaging human infrastructure (e.g., scouring bridge foundations and endangering pumping facilities) in the process. Understanding what controls the rate of bank erosion and associated point bar deposition is necessary to manage large alluvial rivers effectively. In this study, bank erosion was proportionally related to the magnitude of stream power. Linear regressions were used to correlate the cumulative stream power, above a lower flow threshold, with rates of bank erosion at 13 sites on the middle Sacramento River in California. Two forms of data were used: aerial photography and field data. Each analysis showed that bank erosion and cumulative effective stream power were significantly correlated and that a lower flow threshold improves the statistical relationship in this system. These correlations demonstrate that land managers and others can relate rates of bank erosion to the daily flow rates of a river. Such relationships can provide information concerning ecological restoration of floodplains related to channel migration rates as well as planning that requires knowledge of the relationship between flow rates and bank erosion rates. (KEY TERMS: bank erosion rates; fluvial processes; meander migration; rivers/streams; stream power; surface water.)

Lateral erosion of the Sacramento River, California (1942–1999), and responses of channel and floodplain lake to human influences

“…retreat (DWR, 1979;Larsen et al, 2006), and Buer et al (1983) found bank erosion rates at several sites were related to flood magnitude. Thus, we might expect that dam-induced reductions in flood flows (Singer, 2007) should have reduced channel migration rates, an effect that would be compounded by placement of riprap.…”

Channel migration inferred from aerial photographs, its timing and environmental consequences as responses to floods: A case study of the meandering Topľa River, Slovak Carpathians

“…It leads to an increased rate of erosion/deposition processes in the channel (Hooke, 1979;Miller, 1990;Hrádek, 2000;Richard et al, 2005;Larsen et al, 2006;Kiss et al, 2008;Pišút, 2008). Bank erosion processes depend on the size of the discharge and the interactions between the ever-changing hydrological conditions (the flow velocity, local hydraulics, floods and their magnitude, frequency, duration and timing) and other factors contributing to bank erodibility (initial bank geometry, planform geometry, height and density of vegetation, volume of accessible sediments, sediment grain size) (Knighton, 1998;Russell et al, 2004;Luppi et al, 2009), as well as floodplain land cover and overall riverine landscape management.…”

Riparian proper functioning condition assessment to improve watershed management for water quality

“…Lateral instability may be driven by the following: (1) excess sediment supply (Item 5) causing midchannel bars that add to bank shear and bank erosion in places other than the outside of bends; (2) altered flows causing excess bank shear stress (Larsen et al 2006); (3) incision that increases bank stress; or (4) land or water uses that weaken banks through dehydration, poor grazing or recreation management, or removed riparian vegetation by farming, logging, etc.…”

“…Decreased flow velocity increases water residence time, allowing for plants to process/absorb nutrients/pollutants before detained water contributes to post-peak discharge. With energy dissipation, stable banks maintain pattern, profile, and dimension (Item 3), and thereby avoid excess erosion and later insolation (Leopold et al 1964;Larsen et al 2006). Floods have the highest potential for erosive forces and for sediment deposition.…”