MODELING RIVER ICE DYNAMICS USING MIKE11-ICE

English Abstract:

Over the past decade, the close collaboration between LaSalle | NHC, Hydro-Québec and DHI Water&Environment has led to the joint development of river ice modules for the MIKE11 hydrodynamic modeling package, which represents today a state-of-the-art hydraulic modelling tool of Nordic rivers. Two separate modules were developed, the first is for ice generation, transport and accumulation, while the second for formation of ice jams. The ice generation, transport and accumulation module couples the unsteady, one-dimensional St. Venant flow equations with river ice processes. It simulates ice formation in a stretch of river throughout an entire winter season. At every time step and at every point along the river, the model makes a full balance of thermal exchanges between the water, the atmosphere, and stationary or moving ice. The net balance between the gain and loss of heat brings about changes in both water temperature and frazil production that is used to compute the ice discharge – all within the context of the growth of border ice. Typical studies performed with this module are concerned with problems related to flooding due to the formation of hanging dams, water level increase due to the presence of ice in a river reach, ice accumulations on surfaces due to supercooling and the extents and thicknesses of the ice cover for snowmobiling. The second module is for modeling the formation of ice jams following the breakup of an ice cover. The module formulation is based on a stationary mechanical stability of the jam transverse sections, enabling to calculate the ice jam geometry at a specific location along with the resulting water surface elevation profile and velocities. The studies performed with this module cover essentially winter and spring flooding problems caused by ice jams. Typical applications are presented for both modules.