基于概率加权FDC法的河流生态需水量计算

基于河流流量过程的年内和年际变化特性,提出了一种计算河道内生态需水量的概率加权FDC(流量历时曲线)方法。该方法基于年均流量系列和逐月月均流量系列的特定频率,将年均流量系列和逐月月均流量系列划分为丰、平、枯组,通过建立年月丰枯遭遇的Copula联合分布函数,求得不同典型年下各月丰平枯的条件概率,将其作为概率权重,得到不同典型年生态需水过程的计算公式,改进了FDC法,计算出了丰、平、枯典型年的年内生态需水过程。以屏山站为例,将计算结果与Tennant法、逐月最小生态径流法、年内展布法和改进FDC法进行了对比分析。计算结果表明:由此方法得到的生态流量在Tennant法评价体系中,能很好的满足河道的生态需水要求,且较好地体现了河流径流的年内及年际变化过程,符合实际情况。

Using Probability-weighted FDC Method to Calculate Basic River Ecological Flow

Based on the intra-annual and inter-annual change characteristics of the river flow process, this paper put forward a probabilityweighted FDC(flow-duration curve) method to calculate the stream basic ecological flow for the typically wet, normal and dry years. The probability is based on the historical data with the Copula function method. The approach was tested in the Jinshajiang River and the resultswere evaluated by the Tennant standard and compared with month-by-month minimum ecological runoff method, dynamic calculation method and modified FDC method. The results show that the stream ecological demand can be perfectly met. Besides, this approach isreasonable and reliable under the proof of experimental data.