Abstract
Although steady uniform friction formulas have been introduced to the framework of a one-dimensional (1D) hydrodynamic model for centuries, the error of friction calculation inevitably undermines the performance of flood routing. Based on successful results of unsteady channel friction research studies, a newly proposed unsteady friction model is introduced to establish a modified 1D hydrodynamic model (namely, the modified SVN model). With the help of a carefully designed parameter calibration method, the performance of the modified SVN model was compared with that of the original SVN model in a simulation test for a hydraulic experiment. This study’s results revealed that compared with the original SVN model, the modified SVN model could achieve a better simulation in both the flow depth and the sectional averaged velocity simulations. Furthermore, it could reduce the peak value error and the time-at-peak error as well, indicating that the use of an unsteady friction model can efficiently improve the performance of a 1D hydrodynamic model.
Highlights
Based on Saint-Venant equations, the one-dimensional (1D) hydrodynamic model is a fundamental tool for the simulation of 1D flow movement in the case of river or open channel flows [1,2]
Neither carefully designed parameter calibration algorithms nor dynamically updating methods can significantly improve the accuracy of friction calculation, indicating that the classic friction models like the Chezy formula and the Manning formula only work for steady uniform flows but not for unsteady flows
A newly proposed 1D unsteady friction formula was introduced to the framework
Summary
Based on Saint-Venant equations, the one-dimensional (1D) hydrodynamic model is a fundamental tool for the simulation of 1D flow movement in the case of river or open channel flows [1,2] It has been widely used in the fields of hydraulic simulation like flood forecasting and waterway engineering [3,4]. Neither carefully designed parameter calibration algorithms nor dynamically updating methods can significantly improve the accuracy of friction calculation, indicating that the classic friction models like the Chezy formula and the Manning formula only work for steady uniform flows but not for unsteady flows. Rouse [19], Yen [20], and Ding et al [11] argued that in the case of unsteady flow, friction parameters such as the Chezy coefficient and the Manning roughness factor include the components of surface friction resistance, form resistance, wave resistance, and resistance due to flow unsteadiness. The performances of the modified and the original SVN models are compared using a dataset of hydraulic experiments, where a genetic algorithm-based parameter calibration method is used to overcome the difficulties of empirical parameter estimation
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