淮河上游径流年内分配均匀度及变化规律

研究淮河上游径流量的年内分配均匀度及其变化周期,为防洪防汛,水资源的合理规划管理及区域社会经济可持续发展提供决策依据。选取1975—2014年淮河上游2个水文代表站点(大坡岭和长台关)实测逐日流量数据,计算各年平均流量基尼系数和洛伦兹不对称系数,采用线性倾向率、Mann-Kendall突变检验、R/S分析和小波分析等数理统计方法,分析了淮河上游流量的年内分配均匀度、变化趋势及周期特征。结果表明:(1)近40年淮河上游大坡岭和长台关水文站的逐年平均流量均呈微弱下降趋势,其线性倾向率分别为-1.68m~3/(s·10a)和-3.83m~3/(s·10a)。年均流量的基尼系数变化幅度不明显,年平均基尼系数分别为0.54和0.53。洛伦兹不对称系数呈不显著上升趋势,大于1的洛伦兹不对称系数的年份占总年份的比例分别约为65%和57.5%;(2)2个水文站的Hurst指数都略大于0.5,表明存在显著的Hurst现象,即该地区年径流时间序列大体上延续历史变化趋势,说明在未来一段时间内年径流量仍将微弱减少;(3)近40年淮河上游年径流变化主要存在3a,12a和28a的主周期。在气候变化、流域下垫面和人类活动的综合影响下,河川径流的年内分配均匀度发生着相应变化。

Study on Runoff Uniformity and Variation in the Upper Reaches of Huaihe River Basin

Taking the upper reaches of Huaihe River Basin as a case study,we investigated the variation of runoff in order to provide the scientific basis for flood control,water resource reasonably planning and economy sustainable development.Based on daily runoff data from 1975 to 2014 in two hydrological stations (Dapoling and Changtaiguan) of Huaihe River,Gini coefficient and Lorenz asymmetry coefficient in two hydrological stations were statistically analyzed after building the Gini coefficient runoff uneven distribution model,annu al runoff.The characteristics of annual runoff change were analyzed by using the linear regression,MannKendall (MK) test,rescaled range (R/S) analysis,wavelet transforms and other mathematic statistic methods.Some important results were obtained as follows.(1) The runoff trends of Dapoling and Changtaiguan hydrological stations were weak decrease with time at rates of-1.68 m3/(s · decade) and-3.83 m3/(s · decade),respectively.Gini coefficient had a non-significant change.The average Gini coefficients of two stations were 0.54 and 0.53,respectively,indicating that the annual distribution of runoff was heterogeneous.The Lorenz asymmetry coefficients (S＞1) of two stations accounted for 65％ and 57.5％,respectively,indicating that it had greater percentage of the runoff in large runoff months.Lorenz asymmetry coefficient of annual runoff showed insignificant increasing trend,showing that the inhomogeneous degree of the runoff distribution had weak increase.(2) Hurst indexes of the two hydrological stations were slightly great than 0.5 in annual mean runoff by R/S analysis,indicating that there was obvious Hurst phenomenon,and showing that the slight decreasing trend in upper reaches of the Huaihe River would continue in the near future.(3) The oscillating periods of runoff in the past 40 years had complex variation characters with a nested structure on multiple time scales.The wavelet analysis showed that there were three periodic oscillations of 2～5 years,10～15 years and 25～30 years.After the analysis of wavelet variance plots,it was found that there were 3 years,12 years and 28 years periodic fluctuations of annual mean runoff.The two stations might have a quasi-period of 28 years,which need a longer time series to prove.The response of river water resource to both human activities and climate change,as the theoretical basis to understand the river hydrological process and the sustainable use of regional water resources,has gained more and more attentions on water research during the last decades.