Modeling the Release of River Ice Jams and their Impact on River Bed Scouring.

[摘要] The Great Lakes are the largest fresh water reservoir on the planet.Lakes Huron and Michigan drain into Lake Erie through the HuronErie Corridor. The average water level in Lake Huron has been dropping.The results of hydrodynamic model simulations imply that therehas been an increase in the conveyance of St. Clair River that tookplace in the 1980’s. 1984 was marked by a massive ice jam. The jamhad a duration of 24 days and its release was accompanied by highflow velocities. It is speculated that the high water flow velocities followingthe release of the jam caused scouring of the river bed, thatlead to an increase in conveyance.A model is developed to simulate changing river bed morphology,and is combined with a hydrodynamic model in order to simulatescouring during the release of an ice jam. The model consists of modelingthe river bed morphology, finding the sediment fluxes on thebed, and updating the bed morphology when scouring occurs. Thehydrodynamic model uses a step-wise approximation for the bed morphology.A geometric scheme is developed to compute the local angleof inclination. The bed elevation is updated by numerically solving theExner equation by using a finite volume approach. A new methodologyis developed in order to adapt the grid to the changing bedmorphology.The ice jam is modeled as an initially stationary body of water.Water is allowed to flow freely under the body. The body of water isreleased in the flow, accelerating and causing flow velocities over theentire river to rise rapidly. It is found that an ice jam similar to the1984 ice jam will cause scouring of the river bed.

[发布机构] University of Michigan

[效力级别] River Bed Scouring

[关键词] Ice Jam;River Bed Scouring;Mechanical Engineering;Engineering;Mechanical Engineering