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Applicability and Limitations of Channel Routing Models
The choice of a channel routing method depends upon the purposes of the study, the desired level of detail, and the physical characteristics of the watershed in question. In some applications, the transformation of precipitation to streamflow at a particular point of interest can be adequately represented without channel routing. Also, some of the aforementioned methods utilize parameters that cannot be estimated using measurable channel characteristics; they can only be determined through the use of observed data. Moreover, only one of the aforementioned methods (Modified Puls) can simulate backwater effects or the impacts of hydraulic structures. Finally, some of the aforementioned routing methods are only appropriate for use in steep streams with bed slopes > 10 ft/mi.
Initial estimates of channel routing parameters should be subjected to a model calibration process where computed outputs are compared against observed data and model parameters are modified in order to achieve an adequate fit. Also, best estimate parameters derived through the aforementioned model calibration process should be tested through a model validation process where computed results, without any further parameter modifications, are used to compute outputs which are compared against observed data for independent events that were not considered during model calibration. Storm events used during both model calibration and validation should be approximately equal to the magnitude of events that are being considered within the particular application.
The following table contains a list of various advantages and disadvantages regarding the aforementioned channel routing methods available for use within HEC-HMS. However, these are only guidelines and should be supplemented by knowledge of, and experience with, the methods and the watershed in question.
Method | Advantages | Disadvantages |
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Kinematic Wave |
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Lag |
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Lag and K |
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Modified Puls |
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Muskingum |
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Muskingum-Cunge |
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Normal Depth |
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Straddle Stagger |
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