Riverbank Stability Analysis. I: Theory

Osman, Ali; Thorne, Colin R.

doi:10.1061/(asce)0733-9429(1988)114:2(134)

Cited by 387 publications

(246 citation statements)

References 6 publications

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“…Our general goal was to determine through monitoring over a 2-year period whether positive pore pressures associated with subsurface water flow were alone sufficient to instigate bank failures. The role of subsurface water in the failure of gully and river banks has received considerable attention (e.g., Bradford and Piest, 1977;Osman and Thorne, 1988;Higgins et al, 1990;Hagerty, 1991;Darby and Thorne, 1996;Casagli et al, 1999;Simon et al, 2000;Collison, 2001;Simon and Collison, 2001;Amiri-Tokaldany et al, 2003;Dapporto et al, 2001Dapporto et al, , 2003Rinaldi et al, 2004;Darby et al, 2007;Fox et al, 2007;Wilson et al, 2007), and some authors have isolated effects of reduced matric suction in the unsaturated zone (e.g., Fredlund et al, 1978;Casagli et al, 1999;Rinaldi et al, 2004). This study, motivated by observations of bank failures seated below the water table, focuses on only the saturated zone.…”

Section: Introductionmentioning

confidence: 99%

Bank‐collapse processes in a valley‐bottom gully, western Iowa

Thomas

Iverson

Burkart

2008

Earth Surf Processes Landf

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Widening and bank-slope reduction of a valley-bottom gully in western Iowa was correlated to increasing subsurface flow over a 36-year period. To study bank collapse at this gully, we measured rainfall, air temperature, hydraulic head near the banks and bank movement nearly continuously over a 2-year period. Styles of movement ranged from imperceptible creep to rapid slab collapses preceded by the formation of tension cracks parallel to the gully walls. Bank movement was commonly correlated to rainfall or snowmelt and associated head increases in the banks. If the banks are modelled as a twodimensional slab with an adjacent tension crack partly filled with water, measured heads were sufficient to cause bank failures through reduction of frictional support at the base of the slab. During winter months, air temperature variations across 0°C were correlated with bank movement: during mildly subfreezing periods banks expanded, and most, but usually not all, of this movement was recovered during above-freezing periods. This motion is attributed to frost heave followed by thawing. Deformation of the banks by heaving and thawing during winter may weaken them and prime them for failure during spring rains and snowmelt, when the frequency of mass-wasting events is highest.

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Section: Introductionmentioning

confidence: 99%

Bank‐collapse processes in a valley‐bottom gully, western Iowa

Thomas

Iverson

Burkart

2008

Earth Surf Processes Landf

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“…The universal bank erosion coefficient by Hasegawa ͑1989͒ relates the bank erosion rate to the cross-sectional mean velocity, which was validated using data from alluvial channels in Japan. Other researchers ͑Hickin 1974; Nanson 1975,1984;Osman and Thorne 1988; ASCE Task Committee 1998a͒ have related the rate of bank erosion to the geotechnical properties of bank material, but apparently the effects of hydraulic forces also need to be adequately considered.…”

Section: Introductionmentioning

confidence: 99%

Analytical Approach to Calculate Rate of Bank Erosion

Duan

2005

J. Hydraul. Eng.

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Bank erosion consists of two processes: basal erosion due to fluvial hydraulic force and bank failure under the influence of gravity. Because bank resistance force varies with the degree of saturation of bank material, the probability of bank failure is the probability of the driving force of bank failure being greater than the bank resistance force. The degree of saturation of bank material increases with river stage; therefore, the frequency of bank failure is correlated to the frequency of flooding. Consequently, the rate of bank erosion is due to both basal erosion and bank failure, and bank failure is a probabilistic phenomenon. In this paper, for cohesive bank material experiencing planar bank failure, a deterministic approach was adopted for basal erosion analysis, whereas the probability of bank failure was included in the analysis of bank failure. A method for calculating the rate of bank erosion was derived that integrates both basal erosion and bank failure processes, and accounts for the effects of hydraulic force, bank geometry, bank material properties, and probability of bank failure.

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“…Conceptual models of bank retreat attempt to explain this response, describing how bank 43 failure occurs when erosion of the bank toe and the channel bed adjacent to the bank have increased 44 the height and the angle of the bank to the point that the gravitational forces exceed the shear strength 45 of the bank material, resulting in mass failure (Osman and Thorne, 1988). Taking this conceptual 46 model, the stability of river banks can therefore be considered to be controlled by a balance between 47 the gravitational forces acting on the steepened bank, and the resisting forces controlled by the 48 geotechnical strength of the in situ bank material.…”

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confidence: 99%