Periodical characteristics of baseflow in the source region of the Yangtze River
Periodical characteristics of baseflow in the source region of the Yangtze River
复制标题
长江源区基流周期特征
DOI：
10.3724/sp.j.1227.2012.00113
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发表时间：
2012-06
影响因子：
3
通讯作者：
Liang, SiHai
中科院分区：
文献类型：
--
作者：
Qian, KaiZhu;Wan, Li;Wang, XuSheng;Lv, JingJing;Liang, SiHai
基流代表地下水含水层的排泄，是水文流域径流的重要组成部分。长江源区基流的变化典型地反映了寒冷干旱地区地下水系统与气候因子的相互作用。采用改进的Kalinen分离法估算了该地区1957 ~ 2009年的年基流。与总流量的年内变化相比，基流的年内变化幅度较小。在20世纪80年代以前，它处于稳定状态;在20世纪80年代之后，它表现出剧烈的变化和大幅度。在基流计算结果的基础上，应用真实的Morlet小波方法，揭示了研究区基流以及降水和气温的周期性特征。结果表明，年基流具有43年的趋势，以及21年的周期和7年的周期。21年周期最显著，其子波系数波动最大，振幅最大。小波系数在这些时期的总和表现出类似的变化模式，相对于年基流。总流量曲线呈“W”形，这意味着基流遵循下降-上升-下降-上升的四阶段序列。分析表明，基流、降水和温度之间的关系体现在它们在不同时间尺度上的归一化小波系数之间的相关性上。43年小波系数的降水与基流（相关系数为0.98）和气温与基流（相关系数为0.90）均呈显著的线性正相关，表明降水和气温的长期增加趋势将导致基流的增加趋势。对于21年和7年周期的小波系数，降水量与基流之间的线性正相关关系显著。气温与基流的相关性不明显，尤其是21年的相关性更差。结果表明，年基流的变化主要受降水的影响，其次是温度的影响。
Baseflow, which represents the drainage of groundwater aquifers, is an essential component of runoff in hydrological basins. In the source region of the Yangtze River, the change of baseflow typically reflects the in- teractions between groundwater system and climatic factors in cold and arid areas. With modified Kalinen separa- tion method, annual baseflow between 1957 and 2009 in this region was estimated and calculated. In comparison with the inner-annual variations of total streamflow, baseflow showed a weaker fluctuation. Before the 1980s, it was in a steady state; and after then, it demonstrated dramatic variations and large amplitudes. Based on the calculation results of baseflow, the real Morlet wavelet method was applied to reveal the periodical characteristics of baseflow as well as the precipitation and air temperature in the study area. It was found that annual baseflow has a 43-year trend as well as a 21-year period and a 7-year period. The 21-year period is most significant, with its wavelet coef- ficient having the largest fluctuation and amplitude. Summation of wavelet coefficients on these periods exhibits a similar change pattern with respect to that of annual baseflow. The summation curve takes a "W" shape, which means that the baseflow follows a four-stage sequence of descending-ascending-descending-ascending. As analyzed, the relationship among baseflow, precipitation and temperature is implied in the correlation between their normalized wavelet coefficients at different temporal scales. By the significant positive linear correlations both be- tween precipitation and baseflow (correlation coefficient is 0.98) and between temperature and baseflow (correla- tion coefficient is 0.90) for the 43-year wavelet coefficients, it is suggested that the long-term increasing trends of precipitation and air temperature will lead to an increasing trend of baseflow. For wavelet coefficients of 21-year and 7-year periods, the positive linear correlation between precipitation and baseflow is significant. However, the cor- relation between air temperature and baseflow is not so evident, especially for the 21-year period. As a conclusion, correlation analysis with normalized wavelet coefficients showed that the change of annual baseflow was contrib- uted mostly by the change of precipitation and secondly by the change of temperature.
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DOI：
--
发表时间：
2005
期刊：
Hydroelectric Energy
影响因子：
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作者：
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通讯作者：
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影响因子：
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