In order to compute bank failure on either side of any cross section a Groundwater Elevation must be specified. Results will be very sensitive to this parameter. BSTEM does not yet have a physical limit to negative pore water pressure so a very low groundwater table could generate nearly infinite bank stability.
If the static groundwater option is selected, BSTEM will use this groundwater elevation for the entire cross section simulation. If the dynamic groundwater option is selected, the user specified groundwater elevation will become the initial elevation, and groundwater will rise and fall in response to the hydraulic conductivity. The overbank is modeled as a "reservoir" with a volume determined by the distance between cross sections and the user specified "Reservoir Width" parameter in the BSTEM material parameters, which the model moves between the groundwater reservoir and the channel at the rate of the user specified saturated hydraulic conductivity.