| 摘要: |
| 【目的】探索陕北榆林地区河川径流变异类型的识别方法，为进一步了解黄土高原河川径流变化组成及其演变规律与发展机制提供参考。【方法】以陕西榆林22个水文测站的实测年径流序列为研究对象，将经验模态分解（EMD）法与二阶导数法、STARS法、迭代累积平方和（ICSS）法相结合，通过EMD分离径流序列中波动性成分（高频分量）与趋势性成分（低频分量），应用二阶导数法、STARS法和ICSS法对径流序列中趋势变异、均值变异和方差变异进行检验，有效识别不同水文站径流序列的复合变异特征与类型。【结果】陕北榆林地区22个水文站点径流序列总体呈现衰减趋势，年径流衰减速率空间差异较大（-0.06%～-54.73%），对榆林地区的区域用水安全造成了严重的威胁。年径流序列区域变异类型复杂多变，覆盖了未变异，趋势变异，均值变异，方差变异，趋势与均值两重变异，趋势与方差两重变异，均值与方差两重变异，趋势、均值、方差三重变异8种类型。其中，先升后降型和先降后升型的趋势变异主要集中在1960和2000年前后，向下跳跃均值变异主要发生于1970年左右，方差变异则多发于20世纪六七十年代。【结论】陕北榆林地区不同流域的径流时间序列变异程度有差异，且类型复杂多变，趋势变异、均值变异、方差变异基本呈现均势，且复合变异态势显著。在气候变化、下垫面条件变化以及直接人类活动的综合影响下，榆林地区的河川径流变化正在日趋复杂化。 |
| 关键词: 水文序列 河川径流 变异类型 变异识别 陕北榆林 |
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| 基金项目:国家自然科学基金项目(51379014)；陕西省留学人员科技活动择优资助项目（2017035） |
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| Identification of hydrological variation types in river streamflow series in Yulin,northern Shaanxi |
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CAO Wei,ZHANG Hongbo,REN Chongfeng,et al
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| Abstract: |
| 【Objective】This study explored the identification method for variation types of river runoff in Yulin area of northern Shaanxi to provide references for further understanding of the change composition,evolution and development mechanism of the river runoff in the Loess Plateau.【Method】The measured annual runoff sequences at 22 hydrological stations in Yulin,Shaanxi were collected. The empirical mode decomposition(EMD) was combined with the second derivative,STARS and iterative cumulative sum of squares(ICSS) to decompose the streamflow series into intrinsic mode functions (IMFs,i.e.the high frequency component) and residual component (i.e.the low frequency component).The second derivative,STARS and ICSS methods were used to detect the trend changes and the abrupt changes in mean and variance in the runoff sequences for effective identification of compound variation types and characteristics.【Result】The annual runoff sequences of 22 hydrological stations in Yulin,Shaanxi showed attenuation trend,and the annual runoff attenuation rates were significantly different (-0.06%--54.73%),which posed a serious threat to regional water security in Yulin.The regional variation types of the annual runoff sequence were complex and variable,there were 8 types including no variation,trend variation,mean variation,variance variation, double variation in trend and mean,double variation in trend and variance, double variation in mean and variance,and triple variation in trend,mean and variance The trend variations with rising before falling and with falling before rising mainly occurred around 1960 and 2000,respectively.Mean variation with jumping down was at around 1970 and variance variation occurred in 1960s and 1970s.【Conclusion】The variation degrees of runoff time sequences in different drainage basins of Yulin in northern Shaanxi were different and the types were complex.The trend variation,mean variation and variance variation were in balanced situation,and the compound type was gradually dominant The changes of river streamflow series in Yulin region are being more complicated by the influences of climate change,underlying surface changes and human activities. |
| Key words: hydrological time series river streamflow variation type variation detection Yulin,northern Shaanxi |
