【摘要】 应用有限差分法离散分级恒定流数学模型和有限体积法离散非恒定流数学模型，以长江中游宜昌至汉口段为实例，对水位、流量、含沙量和河床冲淤量进行计算分析。结果表明：从上游至下游，分级恒定流数学模型与非恒定流数学模型的计算水位差异有减小的趋势，流量差异则逐渐增大，洪峰和沙峰到达时间比非恒定流数学模型的计算结果提前，含沙量、河床冲淤量和河床高程在部分断面与非恒定流数学模型的结果存在明显差异；随着计算河段的缩短，差异略有减小；随着计算历时的增加，河床冲淤量和河床高程计算差异持续增加。分级恒定流数学模型的计算耗时更长，且计算河段和历时越长，2个模型计算耗时相差越大。建议谨慎应用分级恒定流数学模型。更多还原

【Abstract】 The quasi-steady flow model assumes the flow of the entire reach is consistent with the inlet flow,ignoring the process of flood wave propagation, of which the applicability is far from clear. In this paper, the quasi-steady flow model and the unsteady flow model are discretized by finite difference method and finite volume method, respectively. Taking the middle reaches of the Yangtze River from Yichang to Hankou as an example, the water level, discharge, sediment concentration and riverbed scouring/silting volume are calculated and analyzed. The results show that, from upstream to downstream, the calculated water level difference between the quasi-steady flow model and the unsteady flow model tends to decrease, while the discharge difference gradually increases. The calculated arrival time of the flood peak and the sediment peak of the quasi-steady flow model is earlier than the corresponding calculation result of the unsteady flow model.There are obvious differences between the calculation results of the quasi-steady flow model and the unsteady flow model in terms of the sediment concentration, riverbed scouring and silting volumes and riverbed elevation in some sections. As the calculated reach length is shortened, the differences decrease slightly. With the increase of the calculation time, the differences between the two models of the volume of scouring/silting of the riverbed and the riverbed elevation increase significantly. The calculation time of the quasi-steady flow model is longer,and the longer the reach and duration of the calculation, the greater the difference in calculation time between the two models. When using the quasi-steady flow model to calculate, it is necessary to select empirical parameters cautiously, otherwise large errors are prone to occur.更多还原