Authors: R. Carson, J. Groeneveld
Canadian Dam Association Conference, Winnipeg, September 2008
Abstract
The Red River Floodway was constructed in the mid-1960’s and consists of a 46-km long channel that was designed for a flood discharge capacity of 1 700 m3/s. It is crossed by 13 bridges, 22 transmission lines and a variety of underground conduits for oil, gas, telephone and water supply. A major flood in 1997 severely taxed the flood protection system for Winnipeg. A series of studies followed, and the Government of Manitoba elected to expand the Red River Floodway. Studies of the Floodway Expansion indicated that there could be substantial savings that could be achieved if the channel could vary in width along the route. Maximum channel widening could be pursued in areas remote from crossings, and in locations where the excavation would be primarily in clay as opposed to glacial till. However, in the local areas of crossings, such as at bridges and transmission lines, where costs would vary as a function of the new length of that crossing, the channel widening could be minimized to reduce the overall cost of the project. The overall design capacity of the expanded Floodway was selected to be 3 964 m3/s, and the variations in width of the channel had to be accommodated in achieving that target. A method of optimization was developed that combined all the relevant primary factors and identified the design configuration that would minimize the overall cost of the project. Savings of more than $50 million were estimated to be possible, compared to a simple design that would maintain the same channel width throughout the channel. This paper describes the methodology that was used to develop the optimum design. It is a method that has been used for design of other channels for hydroelectric dams. It is clearly an emerging technology with a high potential for future applications.
