Hydrochemical Characteristic And Interaction Of Surface And Shallow Groundwater In Poyang Lake Area

Poyang Lake is the largest freshwater lake in China with abundant groundwater resources.However,some problems such as over-exploitation,unbalanced development and deteriorating in water quality occurred under the effect of unevenly distribution of the water resources,population,and different development level in agriculture and industry.The objective of this thesis is to study the chemical constituents spatial distribution,hydrogeochemical evolution,and affect factors in both surface and shallow groundwater by tracing groundwater flow through the hydrochemical and isotopic component.This was done by combing field investigating,sampling and water chemical analysis in laboratory,and hydrogeologcial condition.Meanwhile,the thesis explored the interaction between shallow groundwater and surface water by synthesizing the values of ?18 O.Thus provides scientiflc foundation for groundwater resources development and pollution prevention and control.According to the study,the conclusions are as follows:1.Majority of the groundwater was found to be moderately mineralized and weakly acidic.Ca2+ and Na+ are the dominant cations and HCO3-is dominant anions.In the thesis describe the space distribution of chemical components through contour maps.2.Shallow groundwater value of PH,TDS,Na+,Ca2+,Mg2+,Cl-,SO42-,HCO3-,and other components were chosen as initial variables of multivariate statistical analysis.Factor analysis and cluster analysis were used to group the water samples on the basis of their original compositional.Combing factor analysis with hydrogeological conditions,three main factors were separated.From the cluster analysis,we found that these groundwater samples can be grouped into three groups.The first group is assorted with samples situated at the north part of Poyang Lake.Group B,which includes the samples,are almost located at the east and southeast part.Group C contain the rest observations in Ganfu Plain.From Piper Trilinear diagram and ion-plots,the water rock interaction and human activities are identified as the dominant geochemical evolution and determine the major ionic composition.3.HCO3-Ca·Mg is the dominant hydrochemical facies in water of Poyang Lake Basin,Gibbs diagram shows that the water chemistry is largely controlled by rock weathering and contribution from human activities.4.The isotope analysis shows that the samples of shallow groundwater are mostly focus near the GMWL,which indicates modern precipitation is the major origination.For the samples of surface water,most of them drift and below from the GMWL,thus indicates they may be affected by the evaporation.The surface and subsurface water which collected from different areas showed difference in isotope components which indicate that they have different originations or circle processes.Thus,we may learn the interaction between surface and subsurface water from the isotope analysis.In the finally,the transformation between surface water and groundwater is estimated based on mass conservation.