鄱阳湖区地下水位动态及其与湖水侧向水力联系分析

基于野外定点监测数据,运用统计学方法解析鄱阳湖区地下水位年内分布特征和动态变化,辨析湖水和典型区地下水之间的侧向水力联系与程度。统计结果表明,不同洲滩地下水埋深变化范围约–8.1~–0.1 m,洲滩地下水和湖水在6~9月份保持完全水力连通。湖水位和洲滩地下水位动态变化呈现高度一致性,表明了洲滩地下水和湖水具有密切的侧向水力联系。湖岸带不同典型区的地下水埋深变化范围介于–10~–2.2 m。湖岸带地下水位与湖水位并不具有日时间尺度变化上的高度一致性,但两者却很好呈现了月尺度上的较好一致性,表明了湖岸带地下水与湖水之间具有一定的相互关系和水力联系。小波分析得出,湖水位和洲滩、湖岸带不同典型区的地下水位均在60 d尺度的周期上存在着极大可能的显著相关,总体上两者呈正相关关系变化,表明湖水和洲滩地下水具有密切的水力联系,但与湖岸带地下水的侧向水力联系可能体现在个别典型时段。为今后鄱阳湖地下水方面的相关研究奠定基础,也为鄱阳湖湿地生态环境保护、水资源评价等方面提供科学依据和参考。

DYNAMICS OF GROUNDWATER LEVEL AND LATERALLY HYDRAULIC CONNECTION BETWEEN LAKE AND GROUNDWATER IN POYANG LAKE AREA

Study of the interactions and exchange fluxes between groundwater and lake water is an important prerequisite for understanding and preserving groundwater-lake water ecosystems. The objectives of this paper are to combine observed lake water level and groundwater level (during 2014) and statistical methods to analyze the dynamics of groundwater level response to the lake water level changes around Poyang Lake. Additionally, we further explored the laterally hydraulic connection between lake water and groundwater. Statistical results showed that the groundwater depth varies from -8.1 to -0.1 m in different delta wetlands of the Poyang Lake, and the lake water and groundwater had a fully hydraulic connection during the high lake water level periods (June-September). In addition, the variations of groundwater level in the typical delta wetlands were similar to those of the lake water level, suggesting a close hydraulic connection between the two. Statistical results also showed that the groundwater depth has a range of -10~-2.2 m in different lakeshores around the lake. Although the groundwater level in different lakeshores and the lake water level are obviously different at a daily scale in terms of the temporal dynamics, they appear to exhibit similar variation pattern at a monthly scale. The wavelet analysis demonstrated that both the lake water level and the groundwater level in different areas were of obvious 60 days significant oscillation periods with the positive correlations. This result indicates that, in generally, Poyang Lake water has a close hydraulic connection with the groundwater of different delta wetlands, but a relatively weak hydraulic connection between the two depended on the local water regime. The outcomes of this study will not only help improve our understanding of groundwater-lake water dynamics in the Poyang Lake area, but also can provide scientific basis for future groundwater management and water resources assessment.