潇河大坝断面年径流序列随机变化规律研究

Study on Orderliness of Diversification of Runoff in Xiaohe River Dam

采用径流序列分析对潇河流域1957-2007年径流量变化规律进行了研究。结果表明,近50 a来,潇河流域年径流量序列可划分为趋势成分、周期成分和随机成分三部分。其中趋势成分表现为两个方面:一方面是年径流量均值随时间减小,用指数函数表示;另一方面是年径流量在年际间的变化幅度随时间明显减小。周期成分用Fourier级数表示,建模试验表明,该径流序列具有3个显著性谐波,其周期为3.62 a、3.40 a和3.52 a,相应的余弦波系数为0.92、0.49和0.97,正弦波系数为-1.42、-0.43和-0.21。在周期成分中引入振幅衰减因子λ,且λ=0.944 0。独立随机成分宜用P-Ⅲ型概率分布表示。

According to the analysis of runoff sequence, it is studied the evolvement characters of runoff quantity from 1957 to 2007 in Xiaohe River. The results show that： since 1957, the runoff sequence of Xiaohe River can be divided into current component, seasonal component and random component. Current component represents two aspects. One is the equal value of runoff quantity becomes smaller with the time, which can be expressed by the index function. The other is the diversification range of runoff quantity becomes smaller with the time, which can be expressed by the gene of swing attenuation （ .4 ） in the seasonal component. In this paper, a is equal to 0.944 0. The seasonal component can be expressed by the progression of Fourier. The modeling examination shows that the runoff sequence has three notable humorous waves, and their periods are 3.65 years, 3.40 years and 3.52 years, respectively. The coefficients of the corresponding cosine waves separately are 0.92, 0.49 and 0.97. At the same time, the coefficients of the corresponding sine waves separately are -1.42, -0.43 and -0.21. The independence random component is suitable to be expressed by the probability distribution of the P-Ⅲ style.