Framework for control of dynamic ice breakup by river regulation

Abstract

In this paper, we describe and classify the entire range of ice breakup behaviour, from thermal to dynamic, to provide order to this complex process. The theory and model of Ferrick el a f . (198fib) are refined, building on the concept of an intrinsic relationship between river waves and dynamic ice breakup. A force balance is developed for a common dynamic breakup behaviour. Empirical criteria that quantify the resistance to breakup of an ice cover are obtained from a case study and compared with published values. Sensitivity studies of ice breakup with the completed model demonstrate insights that follow from the theory presented, and the intuitive nature of the results. This framework for understanding river ice processes provides the option for ice management by river regulation, and we focus on the potential for control of ice breakup. The concept of controlled breakup involves a release of water from a dam that moves the ice downstream of locations with a high potential for damages during breakup. The abrupt, short-duration characteristics of the controlled release, patterned after those of unregulated river breakup, minimize both the volume of water required to cause breakup and the water levels at breakup. The open water created by the breakup collects heat that increases the rate of melting of the ice. The benefits of successful regulation include the prevention of flooding, minimum erosion and decreased potential for ice damage to structures during breakup without adverse affects on the environment.

The role of ice dynamics in shaping vegetation in flowing waters

“…Through frequent flow releases from existing dams, rivers are kept relatively free from a stable ice cover as well as the consequences of a potential ice break-up (Ferrick & Mulherin, 1989). Because some species in the Peace-Athabasca Delta, Alberta, Canada, are dependent on ice disturbance, the lowered ice volume, lack of ice jams, and lower flooding potential have become a problem on the regulated Peace River (Beltaos, 2000).…”

Ice jam release surges, ice runs, and breaking fronts: field measurements, physical descriptions, and research needs

“…Ferrick and Mulherin (1989) provided a similar description characterizing a "support-dominated" and "strengthdominated" break-up, each corresponding to the sheet front and rubble front, respectively, described in this paper.…”

“…In those cases there may very little rubble underneath the sheet fronts. Ferrick and Mulherin (1989) described support-dominated break-up (or a sheet front in this paper) where "a failure of the supports of an ice cover produces a sudden bank-to-bank release of the ice. This support-dominated break-up travels rapidly downstream at a speed greater than the flow velocity ….…”

Reply to the discussion by S. Beltaos on "Ice jam release surges, ice runs, and breaking fronts: field measurements, physical descriptions, and research needs"

“…In the case of a sheet front there is usually a location somewhere upstream where the ice sheets have been reduced to rubble by repeated collisions and stresses. The discussor as well as others (Ferrick and Mulherin 1989) also refer to that location as the rubble front. The location is often not well defined as in a coincident rubble break-up front, since there is usually a transition zone from ice sheets to rubble instead of a sharply defined front.…”