趋势变异条件下非一致性洪水频率计算方法的择优比较分析——以洞庭湖区弥陀寺站为例

Comparative Analysis of Inconsistent Hydrological Frequency Calculation Methods Based on Trend Alteration: Taking Mituosi Station in Dongting Lake Area as a Case

受到全球气候变化和大规模人类活动等变化环境的影响,特别是长江三峡水库、葛洲坝电站等大型水电工程的兴建,洞庭湖区各站点的洪水序列发生了变异,并引发了洪水频率分布的非一致性问题。以洞庭湖区内弥陀寺站为例,采用线性趋势、非线性趋势、小波分析及希尔伯特-黄变换四种考虑趋势变异的非一致性洪水频率计算方法推求了年最大洪峰流量的频率分布,并进行了四种方法的择优比较分析。结果显示弥陀寺站年最大洪峰流量序列的均值存在显著下降趋势变异,四种方法推求的过去和现状条件下频率曲线的差异较小,而对未来时期的预测差异较大;经择优度计算与比较分析,基于非线性趋势方法所得结果为最优,且进一步得出年最大洪峰流量的频率分布在过去、现状和未来三个时期存在显著的差异,将直接影响洞庭湖区内弥陀寺站附近堤防的安全评价和区域防洪规划。

Due to the climate change and large-scale human activities, especially the environmental changes caused by building the large hydropwoer projects such as the Three Gorges Reservoir and Gezhouba Hydropower Station, the flood series in the Dongting Lake area has altered, which resulted in the non-stationary flood series distribution. Taking the Mituosi Station in the Dongting Lake area as a case, This paper applied four inconsistent hydrological frequency calculation methods including the linear tendency analysis, non-linear tendency analysis, wavelet analysis and Hilbert-Huang transform to calculate the frequency distribution of the annual maximum peak discharge at the station, and made a merit-based comparative analysis. The results show that the mean val-ues of the annual maximum peak discharge series have declined significantly. The difference of the frequency curves calculated by the four methods is relatively small in the past and current conditions while that of the prediction for the future is quite great. Af-ter the calculation of preferred degree and comparative analysis, the results are optimal based on the nonlinear trend method. Fur-thermore, it finds out that there is significant difference in the frequency distribution of the annual maximum peak discharge under the past, current and future conditions, which would directly affect the safety assessment of the embankments near the Mituosi sta-tion and regional flood control planning.