Flow under ice cover and jam effects

Floods resulting from ice jam release events are particularly dangerous because they often occur with little warning and are also associated with dramatic water level rises. The formation of an ice cover over a river channel increases the flow in several ways. The roughness of the ice undersurface is difficult to measure directly, therefore the estimation is sometimes done indirectly from vertical velocity profiles. A model study of the initial ice arching formation of non-uniform fragmented ice floes at the upstream faces of edged and rounded bridge piers was conducted in a hydraulic flume. The experiments were being primarily designed to determine the effects of three critical parameters - shape of ice floes, ice cover roughness and clearance between bridge piers - on arching processes. The influence of the ice cover condition (fixed or loose) and roughness on the velocity profile were also being investigated.