基于PP-RVA法的水电站下游河流水文情势评价

基于对5类33个水文变异指标与生态系统之间的响应关系分析,针对目前常用的变化范围法(RVA法)存在容易忽略低度、中度改变指标,且难以区分各项指标相对重要程度的不足,提出基于投影寻踪聚类模型的改进RVA法(PP-RVA法),对河流水文情势的整体变异度进行评价。以湖南省的刘家坪水电站为例,依据其厂房下游河道的实测径流资料,计算得到建库前后其水文情势的整体变异度为83. 21%,属于高度改变,同时可知5月平均流量、高流量数、最小7 d流量对水文情势改变的影响最大。评价结果更加贴合河道整体信息和指标变异度的分布特征,符合客观实际,表明刘家坪电站当前的运行方式对下游河道的生态系统影响较大,迫切需要开展生态调度实践,实现区域经济和生态环境保护的协调发展。

Hydrological regime evaluation of hydropower station downstream based on the PP-RVA method

The current range of variability approach(RVA)usually ignores the low and moderate variation index, and is difficult to distinguish the relative importance between different indicators when evaluating the overall hydrological regime of a river. Therefore, according to the response analysis of indicators of hydrological variation(IHA)including 33 hydrological indexes from 5 sorts to ecological system, this study improved the RVA approach based on projection pursuit clustering model, which is called PP-RVA and can be used for the effective analysis of river hydrological variation degree. Then, on the basis of runoff data before and after the construction of the Liujiaping Hydropower Station in Hunan Province, the hydrological situation was evaluated by the proposed PP-RAV approach. From the comparison, the overall variability is 83. 21%, which belongs to a high variability. The average flow, high flow rate and 7-day minimum flow in May have the greatest influence on the hydrological regime. The evaluating results fit the overall information of river and distribution characteristics of change degree of index corresponded with the objective reality. Moreover, this study indicates that the current operation mode of Liujiaping Hydropower Station has influenced the ecological system of lower reaches. Therefore, it is urgent to carry out the ecological operation practice to realize the coordinated development of regional economy and ecological environment.