1933~2012年无定河径流突变与周期特征诊断

选取黄河中游区实施水土保持最早的一级支流无定河流域,利用滑动-T、曼-肯德尔和山本等3种突变检测方法相互验证,确定了在受人类活动显著影响下,径流的突变年份为1972年,自此径流平均减少3.55×10⁸m³;基于径流突变前降水与径流的显著相关性,并借助地统计克里格空间插值法,重建1933~2012年无定河流域出口控制水位站天然径流变化序列。采用小波分析法诊断天然径流序列的周期变化,结果显示：天然年径流存在6个不同时间尺度的“丰-枯”演变特征,其平均周期分别对应着35.5、22.2、16.8、12.2、9.3和3.3 a。

The Runoff Abrupt Change and Periodic Characteristics of the Wudinghe River During 1933-2012

River is the path of water current on the land surface that collection and transmission, and the hydrological response of a catchment and hydrological processes which represents the global changes of the response of the earth′s surface. It is of great importance to study the runoff evolvement process. Changing rules and the influence factors in the Yellow River and would enhance sustainable development of social economy and effectively protect our environment under the reasonable utilization of river basin water resources. If we want to identify the ways of response of runoff to climate change in semi-arid region in northwest of China, the study should be first based on the grasp of the long period evolvement rules of runoff. Based on the observed annual runoff data of the Wudinghe River during 1945-2012, the characteristic of the abrupt change had been diagnosed by employing the methods of Moving t-test technique and Mann-Kendall and Yamamoto. The analysis showed that the annual runoff of the Wudinghe River changed abruptly in 1972, in the year since, the decrease of the runoff is about 3.55×10⁸m³ on average. Precipitation decrease about 6.28% but runoff decrease about 26.62% on average after the abrupt change of the Wudinghe River runoff during 1933-2012. Although precipitation was the primary factor to affect surface water resource, precipitation was not the main reason for runoff decrease compared with human activities. Then reconstruct the sequence of natural runoff of the Wudinghe River during 1933-2012 according to the significant correlation between precipitation and runoff before 1972. Morlet complex wavelet function was used to transform the sequence of runoff of Baijiachuan hydrologic stationin of the Wudinghe River during 1933-2012. According to wavelet to analyze the periodic characteristics of the natural annual runoff, the results showed that the average period of annual runoff change have multi-scale periods such as 35.5 a, 22.2 a, 16.8 a, 12.2 a, 9.3 a and 3.3 a. It will be able to calculate the influence degree of the natural runoff change because of human activities such as building a reservoir, building a dam that silting land for developing farmland, etc.