Hindsight on River Ice Jam Stability

Abstract

Following a brief account of the development of ice jam stability theories since the 1960s, inconsistencies in their interpretation for practical applications are identified. In particular, the widely used “bell-shaped curve” is often applied under conditions that do not satisfy the assumptions made in order to derive it. Using the results of later theoretical and numerical developments, it is shown that such applications can lead to significant errors. Analytical predictions of the equilibrium thickness of ice jams should be confined to equilibrium reaches. A simple rule is formulated to resolve the ambiguity of the bell-shaped curve when used to determine ice jam thickness. Use of numerical solutions to the differential equations of stability is recommended for predictions of nonequilibrium ice jam characteristics.