1956-2005年榆林地区河川基流量的小波分析

A wavelet analysis on base flow in Yulin region during 1965-2005

以窟野河、秃尾河和无定河的主要代表站点1956-2005年的基流数据为研究基础,运用非参数检验和小波分析等方法对榆林市50年的河川基流量序列进行了分析。结果表明:窟野河、秃尾河和无定河均存在17-30年大尺度,8-17年中尺度以及3-8年小尺度的3类周期变化规律,其中以中尺度变化周期为主周期。在17年特征时间尺度上,基流量变化的平均周期为10年左右,大约经历了4个"丰"、"枯"转换期,在8年特征时间尺度上,基流量的平均变化周期为5年左右,大约8个周期的"丰"、"枯"变化。研究发现基流量并未严格按照某一特定周期,而是在不同的时间尺度有着不同的变化规律,但从主周期变化规律上来看,基流量呈下降趋势。窟野河、秃尾河和无定河都在1998年发生减少到显著减少的突变。

Based on the data of base flow from 1956 to 2005 of the main hydrometric stations of Kuye river,Tuwei river and Wuding river,the time series of base flow on the scale of 50 years was analyzed by the methods of wavelet analysis and Mann-Kendall abrupt test.Study found that all the research areas had three types of periodical law,they the large scale of 17 to 30 years,the mesoscale of 8 to 17 years and small scale of 3 to 8 years;the mesoscale was the main periodical law.On the scale of 17 years,the average switching cycle of base flow was 10 years,which experienced about 4 switching cycle from high flow period to low flow period,On the scale of 8 years,the average switching cycle of base flow was 5 years,which experienced about 8 switching cycle from high flow period to low flow period.Study found that base flow did not follow a certain periodical law,which had different changing low on different scale,but from the scale of 8 to 17 years,the amount of base flow was on a declining curve and all the research areas had an abrupt change in 1998.