黄河中下游地区旱涝分型及突变的初步分析

A STUDY ON DRYNESS/WETNESS DISTRIBUTION AND ABRUPT CHANGE IN MID-LOWER REACHES OF THE HUANG HE (YELLOW) RIVER VALLEY

采用CEOF(复经验正交函数)对黄河中下游地区15个代表站点近500年来的旱涝等级指数分析结果表明,历史时期本地区的旱涝分布特点可用三种分布型表征:平均型、东西反相型和南北反相型,对上述三种旱涝分布型的时间振幅,应用Mann-Kendall方法进行突变检验,可以发现平均型和东西反相型近500年来发生旱涝突变,而南北反相型则相对比较稳定。

In this paper the temporal and spatial distribution of the dryness/wetness changes during the last 500 years in the mid-lower reaches of the Huang he (Yellow) River Valley has been investigated through a few approaches. By carrying out the CEOF analysis of the graded dryness/wetness data during 1470?979 from 15 stations in this region, three spatial patterns have been derived. They are Mean Pat-tern; East-West Pattern and South桸orh Pattern, of which the explained variances occupied 37.5%, 143%, 7.9%, respectively. In order to demonstrate some events of abrupt dryness/wetness changes during Historical Times in this area, the temporal amplitudes of the three patterns have been analyzed by Mann-Kendall test and the result shows that the abrupt change for the Mean Pattern appeared in 1520 reflected an abrupt increase of drought/flood frequency and that for the East梂est Pattern appeared in 1793 marked the beginning of weakness of this Pattern.