R2CROSS方法在南方中小型河道生态流量计算中的适用性和优化讨论

Applicability and Optimization of R-2CROSS Method in Ecological Flow Calculation of Small-and-Medium Sized Rivers in South China

为研究R2CROSS法在南方小型河流生态流量计算中的适用性,分析了R2CROSS方法中湿周率参数的适用条件、典型断面的选择,以及其他水力参数的合理取舍,并提出优化建议。对于R2CROSS方法中的湿周参数,鉴于该方法中对浅滩式河流临界状态的假定前提,在受人类改造影响较大的河道断面中,湿周率参数适宜作为评价因素而非计算因素考虑;对于平均水深和平均流速两个参数,在逐一分析不同水力参数之间的关系的基础上,提出一种参数取值的优化方法:通过推求水深和流速间的量化关系建立了h 23~u曲线,配合同步约束区间,可以较为方便和快速的确定R2CROSS法中平均水深、平均流速参数的合适取值,并从多个断面中选择出适合生态系统水力条件的典型断面。

In order to investigate the applicability of the R-2 cross method in ecological flow calculations of small rivers in southern China,the following optimization suggestions are made after analyzing the applicable conditions of the wetted perimeter ratio,the selection of typical cross section,the reasonable selection of other hydraulic parameters and the composite constraints.Considering the assumptions made in the R-2 cross method for the critical condition of wide and shallow rivers,it is appropriate for the wetted perimeter ratio parameter to be considered as an evaluation factor rather than a computational factor in stream cross-sections that have been heavily influenced by human modification.Based on an analysis of the relationship between different hydraulic parameters,an optimization method of hydraulic parameters in R-2 cross method is proposed.By calculating the quantitative relationship between water depth and velocity,the h 23~u curve is established.With the composite constrained interval,it is convenient and fast to determine the appropriate values of average-depth and average-velocity parameters in R-2 cross method.The typical section suitable for the hydraulic conditions of ecosystem can also be selected from multiple sections by using the optimization method.