The ability to predict the stability of eroding riverbanks is a prerequisit
e for modelling alluvial channel width adjustment and a requirement for pre
dicting bank erosion rates and sediment yield associated with bank erosion.
Mass-wasting of bank materials under gravity occurs through a variety of s
pecific mechanisms, with a separate analysis required for each type of fail
ure. This paper presents a computer program for the analysis of the stabili
ty of steep, cohesive riverbanks with respect to planar-type failures. Plan
ar-type failures are common along stream channels destabilized by severe be
d degradation. Existing stability analyses for planar-type failures have a
number of limitations that affect their physical basis and predictive abili
ty. The computer program presented here is based on an analysis developed b
y Darby and Thorne. The software takes account of the geotechnical characte
ristics of the bank materials, the shape of the bank profile, and the relat
ive elevations of the groundwater and surface water to estimate stability w
ith respect to mass failure along a planar-type failure surface. Results ca
n be displayed either in terms of a factor of safety (ratio of resisting to
driving forces), or probability of failure. The computer analysis is able
to determine the relative amounts of bed degradation and bank-toe erosion r
equired to destabilize an initially stable bank. Data for the analysis are
supplied in the form of either HEC-2 hydrographic survey data files or user
-supplied bank profile data, in conjunction with user-supplied geotechnical
parameter values. Some examples, using data from the Upper Missouri River
in Montana, are used to demonstrate potential applications of the software.
Copyright (C) 2000 John Wiley & Sons, Ltd.