Analysis On Influence Of Chemical Composition Of Groundwater In Liangji Canal On South-North Water Transfer Project In Operation

Based on hydro-chemistry elements of shallow groundwater in Liangji Canal Basin before and after South-North Water Transfer Project in operation, ion correlation analysis,piper diagram, ARIMA, the ions ratio coefficients and other methods were used to analyze the impact of water transfer on the chemical composition of shallow groundwater. The aim of the research is to clarify the status of the typical characteristics of shallow groundwater and its key driver factors, to reveal function of the chemical composition in the groundwater, and to analyze the impact of transferring water on the chemical composition of shallow groundwater,in order to provide a scientific basis and management ideas for both healthy operation of water diversion project and ecological operation of the flowing through areas.The results are shown as follows:①By the analysis of ion correlation, SO42-, HCO3-, Ca2+ and Mg2+ in groundwater near by 6# observation well of Rencheng area were due to the dissolution of dolomite and gypsum,those in shallow groundwater near by 99# observation well of Liangshan area were due to deposition of carbonates containing calcium, magnesium and weathering dissolution of metamorphic rocks containing magnesium mineral.②By the statistical analysis of water chemistry parameters, it can be found that the mean concentration of cation and anion has no significant change through the 6# observation well in the Rencheng before and after the water passing, and sort is still Ca2+>Na+>K+>Mg2+、HCO3->SO42->Cl-. After the water passing, the mean concentrations of anions changes a little in the Yellow River flooding plain, and is still HCO3- > SO42- > Cl-. But the mean concentrations of cations changes obviously, by Na+>K+>Mg2+>Ca2+ into Ca2+>Na+>K+ > Mg2+. In terms of salinity, the shallow groundwater TDS is less than 1.0 g/L in the Rencheng 6A# observation wells on the lake district and it is freshwater; the shallow groundwater TDS is between 1.0 and 3.0 g/L on the Yellow River flooding plain which is brackish water. The groundwater salinity were both decreased on the Lake District and the Yellow River flooding plain after water passing.③ Before the project being completed, Ca2+-Mg2+-HCO3- was major chemical constituent in the Lake District’s shallow groundwater, while in the Yellow River Flooding Area’s, Na++K+-Cl--SO42- and Ca2+-Mg2+-Cl--SO42- types were dominant. And in the period of water transferring, nothing changed in the Lake District’s shallow groundwater, but Ca2+-Mg2+-HCO3- types were dominant in shallow groundwater of some Yellow River Flooding Area.④The influence of Water Transfer on the chemical composition of groundwater of the Lake District is weaker. Water contained with low salinity and massive CO2 was injected into shallow groundwater of the Yellow River Flooding Area, which promoted the decomposition of limestone component, and result in significantly increasing in Ca2+.