山西省大中型水库年径流变化趋势分析

Analysis on the Fluctuation Trend of Annual Runoff Entering into the Large and Mediumscale Reservoirs in Shanxi Province

山西省水资源紧缺，近年又呈下降趋势，严重影响了山西省国民经济的发展。大中型水库是山西省的命脉供水工程，研究全省大中型水库的年际来水变化情况，具有很实际的意义。本文采用了坎德尔秩次检验法检验水库径流的趋势性，采用有序聚类法找出径流系列的跳跃点，用秩和检验法检验跳跃点的显著性，用线性回归法对跳跃点前后累积径流系列进行回归分析，并对其进行Ｆ检验，最后得出全省４０座大中型水库的径流趋势变化结果，作出“大中型水库年径流下降率频率分布图”、“大中型水库第一类跳跃点频率分布图”，分析结果表明：山西省大中型水库大部分下降趋势，下降率大部分集中在０．４～０．７之间，产生下降的年份大都在１９７６～１９８５年间，１９７６～１９７７年尤为显著。

The fluctuation trend of annual runoff entering into the large and mediumscale reservoirs in Shanxi Province is analysed, in which the tendency of annual runoff entering into the reservoir is tested with the method of Kendall′s rank tests, the jump point of annual runoff series is found out with the method of the order cluster analysis,its significance is tested with the rank sum test method, a regression analysis for cumulative runoff series before and after the jump point is done using the linear regression method,and which the Ftest is given.Finally,an analysis result on the fluctuation trend of annual runoff that enters into 40 of the large and mediumscale reservoirs has been obtained. The frequency distribution diagrams both for the descending rate of the annual runoff and for the jump point of the first type having descending trend have also been drawed therewith. The analysis shows that most of the annual runoff flowing into the large and mediumscale reservoirs are of the descending trend,plenty of the descending rate concentrates on 0.4～0.7, the greater part of the descending occurred in 1976～1985,especially remarkable in 1976～1977.The writers point out that the cause of the descending and its future trend after 1990′s need to further be researched as a great interest is now focused on these problems.