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Abstract

Recent developments in flood routing have resulted in several numerical models with different features. These models produce different results, and the discrepancies between computed and observed flows vary depending on the values of the channel’s friction coefficient and bed slope. The objective of this study is to find the most reliable model for a particular range of combinations of channel friction coefficient and bed slope. Results from five flood routing models -- the dynamic wave, the characteristic, the kinematic wave, Muskingum-Cunge and UBC Flow models -- were compared. The first three models are based on a hydraulic approach, but they solve the unsteady flow equations with different methods. The fourth model is based on the hydrological approach, and the last one is a hybrid model. Whith some modifications, these five different models were run using the same input parameters, and their results were compared. The comparison consists of two steps. The first involved applying the models to a set of actual Fraser River flows. The second involved comparisons of the results when the models were applied to an artificial channel with various friction coefficients and bed slopes. The latter procedure was used because of the difficulties in obtaining sufficient data from natural rivers. The computed Fraser River flows from all the above models had a good agreement to the observed outflows. However, the most accurate result was that from the dynamic wave method, followed by those from the characteristic, the kinematic wave, the UBC Flow and Muskingum-Cunge methods respectively. There are two main results from this study. First, the most reliable model is the dynamic wave method because of its accuracy and applicability, and second, the discrepancies between computed and actual flows decrease with smaller friction coefficient or steeper bed slope channel.