基于小波分析与Mann-Kendall法的岩溶大泉动态研究

Study of large karst springs using the wavelet analysis and Mann-Kendall methods

研究地下水动态是认识地下水资源的有效手段。根据1956-2013年济南岩溶泉域大气降水及地下水水位动态监测资料,采用小波分析法、Mann-Kendall趋势检验、突变检验法研究了58个水文年泉水位对大气降水的响应,可以看出:(1)大气降水和泉水位呈现出多尺度的变化特征,长时间尺度上两者的变化周期基本相同,变化周期为16年和12年,说明大气降水对泉水位有直接影响;(2)在1956—2013年,济南泉域地下水水位具有0.65m·(10a)^(-1)的年际显著下降趋势,但降水具有12.65mm·(10a)^(-1)的不显著上升趋势,说明在人为因素影响下泉水动态的影响因素的权重发生了变化;(3)大气降水在1999年发生突变,1999年之后年降水为增加趋势;而地下水水位突变年份为1967年,1967年以后水位持续降低,2004年以后水位快速上升,泉水位未来趋势应与降水保持一致,呈上升趋势,说明大气降水并非泉水动态的唯一影响因素;(4)通过建立不同时段的多元回归模型,表明近58年来地下水水位的主要影响因素由大气降水到人工开采之间的转换,同时验证了小波分析和Mann-Kendall法研究地下水动态的适宜性和可靠性,也为济南市的保泉提供了参考依据。

The study of groundwater dynamics is one of the most effective ways to understand the nature of groundwater resources.According to the monitoring data of precipitation and groundwater level in the Jinan karst spring area from 1956to 2013,this work studies the spring water level response to atmospheric precipitation during these 58years using the wavelet analysis,Mann-Kendall trend test and mutation test.The results show that,（1）the precipitation and spring water level show a feature of multi-scale variation,and the change cycle is basically the same on a long-term scale,which are 16years and 12years,respectively.It means that atmospheric precipitation has a direct impact on the spring water level.（2）From 1956to 2013,the groundwater level in the Jinan spring area had a significant downward trend of 0.65m·（10a）^（-1）,while the precipitation had an upward trend of 12.65mm·（10a）^（-1）,which is not significant,indicating that the weight of the influencing factors of spring dynamic has changed under the influence of human factors.（3）Furthermore,there has been a mutation of atmospheric precipitation which occurred in 1999,and the annual precipitation increased after 1999.However,the groundwater level mutation appeared in 1967,while the water level continued to decrease after 1967and then increased rapidly after 2004.The future trend of the spring water level should be kept consistent with the precipitation and show an upward trend,indicating that atmospheric precipitation is not the sole factor affecting the dynamics of the spring.（4）The results from multivariable regressions for different periods of time suggest that the main influencing factors of groundwater level in the past 58years are the transition from precipitation to artificial mining;at the same time,it validates the suitability and reliability of wavelet analysis and the Mann-Kendall method to study groundwater dynamics,and also provides a reference for the protection of the spring in Jinan City.