Because of difficulties in the field monitoring of overhanging riverbanks, it is not possible to monitor its deformations before failure, and therefore it is sometimes admittedly difficult to discriminate between shear versus toppling failures in the field. In This paper evaluated the extent to which uncertainties in the parameterisation of controlling factors feed through to influence the reliability of the resulting overhanging stability estimate.  Thus, the impacts of variations in each individual parameter on the factor of safety are investigated, while keeping all other parameter values constant. In estimating the magnitude of the uncertainty typically associated with each of the parameters, discriminating between (i) measurement errors and (ii) uncertainties associated with the inherent natural variability of each parameter is helpful. The results showed that the care should be taken when estimating the values of cantilever block height, block width, tension crack depth, block material cohesion, and the block material unit weight as the safety factor is more sensitive to the variation of these factors. Since parameter uncertainties are derived primarily from the inherent variability of the parameters, rather than measurement errors, much more careful attention should be paid to field sampling techniques.