鼎湖山流域下游浅层地下水动态变化及其机理研究

Dynamic features and mechanisms of shallow groundwater in the downstream of Dinghushan Biosphere Reserve

全球变暖和降水格局的改变将如何影响下垫面水文过程是一个被普遍关注的重大科学问题,然而要阐述其内在联系首先必须排除人类活动及土地格局变化的影响。论文以严格保护下的鼎湖山自然保护区为研究对象(排除人类活动及土地格局变化的影响),以其完整集水区下游区域地下水测井系统测定的地下水位数据为基础,拟阐述全球变暖和降水格局改变对该地区地下水位多年变化动态及趋势的影响机制。结果表明:2000年至2009年10 a间鼎湖山流域下游浅层地下水位由2000年的–2.27 m上升到2009年的–1.81 m,年均极显著(p=0.005)上升0.043 m.a-1;地下水位干湿季差异显著,湿季地下水位显著(p<0.001)高于干季,分别为–1.87±0.23 m、–2.25±0.15 m。时间序列上,干季地下水位无显著(p=0.190)变化,湿季(1999-2009年)地下水位呈极显著(p=0.002)上升趋势;日地下水位变异系数CVwt=0.20明显小于日降水量CVp=2.77,日地下水位动态与前40 d的日降水量有关;地下水位的变化不能用同期内降水量变化(p=0.294)解释,分析认为降水格局的变化是导致地下水位上升的基本原因。该研究对评估降水格局改变和全球变暖环境下,地下水资源的变化趋势有重要指示意义。

How climate warming and precipitation pattern change affect hydrological processes is a challenging problem which has attracted great attention universally. However it＇s extremely essential to remove the effects of human activity and land use change when dealing with its underlying mechanisms. Based on the long-term data monitored by the groundwater well in Dinghushan Biosphere Reserve, we attempted to elaborate the patterns, trends and dynamic mechanisms of the shallow groundwater table at intra- and inter-annual time scales in this intact forested watershed. The main conclusions were as follows. During the period of 2000-2009, the annual mean groundwater table in Dinghushan increased significantly from -2.27 m to -1.81 m with a rapidity of 0.043 m＇at （p = 0.005） The groundwater table in dry and wet season was （-1.87 ＋ 0.23） m and （-2.25 q- 0.15） m, respectively, which was significantly higher in wet seasons than in dry season （p 〈 0.001）. Further analysis indicated that the notable uptrend of annual mean groundwater table was mainly attributed to the significant increase of groundwater table in wet season （p = 0.002）, while the dry season groundwater table changes were not significant with the time （p = 0.190）. CV（coefticient of variation） of daily groundwater table （CVwt= 0.20） was less than the precipitation （CVp = 2.77） obviously; meanwhile, the groundwater table depth of the eastern watershed in Dinghushan was significantly correlated to the total precipitation of 40 days before. The change of groundwater level could not be explain by the changed precipitation （p = 0.294） in the same period, and the precipitation pattern change was analyzed to be the basic reason for the increased groundwater table. In the context of global warming and precipitation pattern change, this study conveys a denotative meaning in assessing the groundwater resources dynamic.