潮流界以下河段航道整治水位确定方法研究——以长江江阴以下河段为例

Study on calculation methods of regulation stage in reaches downstream of tidal current limit——a case of the reaches below Jiangyin

在总结分析现有整治水位确定方法的基础上,根据潮流界以下河段的水沙运动特性,本文提出一种基于输沙能力的航道整治水位确定方法。考虑上游来水、下游潮汐为独立事件,统计潮流界以下河段上游来水、下游潮汐不同等级组合出现的频率,采用数学模型计算相应组合下河段沿程的潮位、流速过程,以流速四次方代表水流的输沙能力,统计不同潮位等级对应的综合净输沙能力,确定最大综合净输沙能力对应的水位为(最优)航道整治水位。以长江下游白茆沙水道和福姜沙水道为例,计算了所在河段的航道整治水位,并探讨了起动流速对整治水位计算的影响和最高整治水位概念对工程的意义。

A new method of defining the channel regulation level depending upon the sediment transportation capacity is proposed in association with the characteristics of water and sediment movement in the reaches of a river below tidal current limit after a brief summary of existing methods of calculating the channel regulation level.Taking incoming water upstream and tides downstream as independent events,the paper statistically analyzes the frequencies of various combinations of incoming runoff and tides at the sections of a river below-tidal current limit,calculates with a mathematical model the tidal level and velocity processes along the sections under relevant combinations of runoff and tides,and,with the sediment transportation capacity of the current being expressed in terms of velocity to the fourth power,calculates the comprehensive net sediment transportation capacity(which is weighted with frequencies of the combinations of runoff and tides)corresponding to different tidal levels,and finally defines the level corresponding to the max.comprehensive net sediment transportation capacity as the(optimal)channel regulation level.Baimaosha and Fujiangsha Passages downstream of Jiangyin are cited as an instance in the paper to calculate the regulation level.The influence of incipient velocity on the calculation of regulation level and the meaning of the concept of the highest regulation level are discussed.