Author(s): Michael Morris; Jarrod Malenchak; Joe Groeneveld
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Abstract: There are several locations on the Nelson River in northern Manitoba that are susceptible to the growth of anchor ice. Two of these locations are of particular interest to Manitoba Hydro due to their close proximity to the existing Limestone Generating Station and the future Conawapa Generating Station. Anchor ice growth at these locations can result in elevated tailwater levels over the winter period, directly impacting the winter generation capacity of each station. The ability to predict the potential for anchor ice formation at these two locations, once the Conawapa station has been constructed, is an important aspect in the new station’s planning process. This paper outlines the results of an investigation which used CRISSP2D’s two-dimensional thermodynamic ice model at these two locations. CRISSP2D was applied to simulate the river’s post-Conawapa thermal ice regime under winter conditions. This information was then used to provide guidance to planners on possible anchor ice growth/effects at these two locations. The first model extended approximately 4.5 km from the existing Limestone GS to a location downstream of Sundance Rapids which is approximately 26 km upstream of the Conawapa axis. Currently, anchor ice forms across Sundance Rapids every winter, but will be flooded by an additional 4.5m of water once the Conawapa station is constructed. It has been assumed that once impounded, anchor ice will no longer form. This study will attempt to confirm these assumptions. The second model was located in the proposed Conawapa tailrace channel. Anchor ice has been observed to form on a shoal approximately 1100 m downstream of the station axis. This study will help identify the potential for anchor ice to continue to form once the generating station is constructed and operational.
Year: 2008