热带地理

TROPICAL GEOGRAPHY ›› 2017, Vol. 37 ›› Issue (4): 522-529.doi: 10.13284/j.cnki.rddl.002956

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Interactions between Groundwater and Lake Water of Riparian Zone in the Typical Area of Poyang Lake

LI Yunliang1，ZHAO Guizhang2，YAO Jing1，ZHANG Qi1,3   

  1. （1．Key Laboratory of Watershed Geographic Sciences，Nanjing Institute of Geography and Limnology，Chinese Academy of Sciences，Nanjing 210008，China；2．North China University of Water Resources and Electric Power，Zhengzhou 450000，China；3．Key Laboratory of Poyang Lake Wetland and Watershed Research，Ministry of Education，Jiangxi Normal University，Nanchang 330022，China）
  • Online:2017-07-05 Published:2017-07-05

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Abstract:

Study of the interactions between groundwater and lake water is helpful to improve the understanding of water resource management, hydrogeochemistry, biogeochemistry and eco-hydrology in lakes. Hydraulic relationship between groundwater and lakes has become an important topic for the scientific and decision-making communities. Poyang Lake, the largest freshwater lake in China, has significant seasonal lake water level variations. This will cause the groundwater level changes in the riparian zone of the lake, and hence affect the water resource characteristics in the local area. This paper selected riparian zone of Poyang Lake (China) as the typical study area. We used groundwater and lake water level observations, groundwater velocity and flow direction measurements, and hydrochemistry signatures to identify the recharge and discharge between groundwater and lake water. Results show that ,SO2-4, Ca2+ and Mg2+ are the major anion and cation in both the groundwater and lake water. The flow direction of the riparian groundwater is mainly from the upstream mountainous areas to the downstream plain areas, indicating an inclined surface from the recharge area to the discharge area. Generally, the riparian groundwater flows to the river and the lake in the study area. Field observations also indicate that the spatial distributions in groundwater level have a decreasing trend from the upstream to the downstream areas. Although the riparian groundwater exhibits obvious dynamic changes, the magnitude of groundwater level variations is generally less than 2.0 m. Additionally, groundwater velocities are distinctly large (up to 19.5 m/d) in the upstream mountainous areas, which are far from the lake zone, and those are relatively small with a mean value of 5.1 m/d close to the lacustrine area. The spatial pattern of groundwater level and groundwater velocity coincides with the surface topographical changes, suggesting an important effect of the topography on the local groundwater flow. The evidences of hydrochemistry indicate that the lake water and groundwater have a hydraulic link. In addition, the groundwater velocity field and seasonal dynamics for both the groundwater level and the lake water level demonstrate that the riparian groundwater may discharge to the lake with different water fluxes. Our study is the first attempt to perform a field work on the interactions between groundwater and lake water, which can provide scientific knowledge for the water resource management and environmental assessment in Poyang Lake.

Key words: groundwater-lake water, hydrodynamic field, recharge and discharge, riparian zone, the Poyang Lake