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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 base flow data of the main representative stations of the Kuye River, Tuwei River and Wuding River from 1956 to 2005, non-parametric test and wavelet analysis were used to analyze the 50-year river base flow series of Yulin. The results show that there are three types of periodic variation in the Kuye River, Tuwei River and Wuding River in 17-30 years of large scale, 8-17 years of middle scale and 3-8 years of small scale, of which the mesoscale variation period cycle. On the characteristic time scale of 17 years, the average cycle of base flow changes is about 10 years, and about 4 “Feng ” “ ” transition period. On the characteristic time scale of 8 years, The change cycle is about 5 years, about 8 cycles “Feng ”, “dry ” changes. The study found that the base flow did not strictly follow a specific cycle, but had different variation rules at different time scales. However, the base flow showed a declining trend from the main cycle variation. The Kuye River, Tuwei River and Wuding River all experienced mutations that were reduced to a significant decrease in 1998.