© 2019 Union of Croatian Civil Engineers and Technicians. All rights reserved.The causes of uncertainty involved in temporal variation of the depth of cavern formation due to clear water scouring at dual piers with tandem arrangement are identified in this study. In an example, the probability of failure induced by scouring around dual piers is estimated for various pier spacing using probabilistic analysis. The effects of changes in the coefficient of variation of probabilistic scouring variables and probability distributions on the probability of the loss of stability, are also investigated. It was established that the effects of variations in the coefficient of variation on the probability of the loss of stability are more significant compared to that on the probability distributions of the scour depth.