基于湿周法的西南山区河流生态需水的计算与验证

研究湿周法的适用条件及转折点的确定方法,为计算河流最小生态需水提供参考。收集了我国西南山区岷江和大渡河流域河流上、中和下游共计8个水文站的实测大断面数据,通过建立各断面湿周与流量关系及其拟合曲线,分别采用斜率法、曲率法和经验法分析确定了各断面最小生态需水,并参考相关参数标准对计算结果进行了合理性检验。研究表明,湿周法适用于河床稳定且形态近似抛物线形或矩形的断面,以斜率为1的点(斜率法)确定断面湿周与流量关系曲线的转折点及断面最小生态需水更有利于保护河流生境;对于形态近似为抛物线形或矩形的断面,其计算结果约占多年平均流量的8.9%~13.2%,各断面最小生态需水所对应平均水深、湿周率和平均流速均能满足检验标准。湿周法适用于近似抛物线形或矩形的断面,不建议用于近似三角形或梯形的断面。

Calculation and Verification of Ecological Water Demand in Southwestern Mountain River based on Wetted Perimeter Method

In order to discuss applicable conditions of the wetted perimeter method and turning point determination method, based on the measured data of the different forms section in southwest mountainous rivers, establish the relationship between the wetted perimeter and flow and its fitting curve of each section. The slope method, curvature method and empirical method were used to define minimum ecological water requirement of each section. The case study indicates that wetted perimeter method is suitable for approximate parabolic form or rectangular cross section of the stable riverbed, using the slope method (the point which slope equal to 1) to determine the turning point of relation curve between the wetted perimeter and flow, and the minimum ecological water requirement of each section, will be more conducive to protect the river habitat. For approximate parabolic form or rectangular cross section, the calculation results of wetted perimeter method accounts for about 3.9% ~ 13.1% of the average flow rate for many years, the corresponding average water depth, wet frequency and average flow velocity of river section can meet the inspection standards.