Hydro-chemistry characteristics of regional groundwater in the context of "flood season drought" in the middle reaches of the Hanjiang River basin in 2022
In June 2022,a large-scale severe drought broke out in the Yangtze River Basin due to abnormal atmospheric circulation and other factors,resulting in the abnormal phenomenon of ＂flood season anti-drought＂,which continued until the winter of that year.As the largest tributary of the Yangtze River,the Hanjiang river was studied by selecting the groundwa-ter around the banks of the Xiangyang section of the middle reaches of the Hanjiang river as the research object,and analyzing the chemical characteristics and dynamic changes of groundwater in the area by using multiple statistical analysis,Piper three-line diagram,principal component analysis,Gibbs plot and other methods.The results showed that the chemical types of groundwater in the study area were mainly alkaline water with low salinity,The cations in the groundwater components are mainly Ca2+and Na+,and the anions are mainly HCO3-.In September,the groundwater pH was high,and the groundwater salinity decreased.In June,the shallow groundwater types around the Xiangyang section of the Hanjiang river Basin were mainly HCO3·SO4-Ca·Mg type,and there was a trend of groundwater conversion to HCO3-Na type water in September,The change of ion concentration is mostly the overall change,which may be related to the lateral recharge of the surrounding aquifer.The hydro-chemical characteristics of groundwater are controlled by the weathering and dissolution of surrounding carbonate rocks and silicate rocks.The cation exchange adsorption of groundwater near the downstream area is strong,which is affected by drought and less rain,resulting in a significant weakening of cation adsorption in this area.
middle reachesof Hanjiang Riverflood season droughtgroundwaterhydro-chemistry characteristicsfactor analysis
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