Author(s): Robert Gerard; Dejiang Long; Leslie F. Sawatsky; Terry Winhold

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Abstract: Dickson Dam, which was constructed in 1983 and located about 58 kilometres upstream of the City of Red Deer, has caused major changes to the ice regime of the Red Deer River at the City of Red Deer. The review of historical breakup ice regime prior to the construction of Dickson Dam shows that ice jams have caused highest tlood levels, loss of life, and significant damage to property. The new ice regime at breakup is characterized by thermal breakup, reduced discharge, and reduced ice quantities at the breakup front. A thermal-breakup model was developed, calibrated, and used to hindcast the time of breakup for events prior to the construction of Dickson Dam, assuming the conditions of the new ice regime. Two probability distributions of ice-related floods were derived. One provided the lower bound, which was determined by assulfling thermal breakup in each year. The other provided the upper bound, which was determined by assuming mixed thermal and dynamic breakups. The results show that both distributions are below the probability distribution of open water floods. The study concludes the foJJowing: (1) the construction of Dickson Dam has significantly reduced the ice jam flood threat at the City of Red Deer; and (2) the open water floods govern the future flood events if Dickson Dam continues to be operated in accordance with existing criteria.

DOI:

Year: 1992