Study On Dynamic Characteristics Of Groundwater And Age Distribution Of Groundwater In Yinchuan Plain

Three typical sections of the central,southern and northern parts of the Yinchuan Plain were selected,Using MODFLOW to simulate the flow model of the profile.Based on the water flow model,the groundwater ¹⁴ C solute transport model was constructed.The cyclic isotope 3H,¹⁴ C dating on the section of the Yinchuan Plain from the profile level of the groundwater cycle system characteristics,the characteristics of the bucket row and the groundwater age characteristics of the analysis.Firstly,the dynamic characteristics of groundwater in the Yinchuan Plain is divided into three types: runoff type,irrigation type and mining type.The influence coefficient of groundwater dynamic factor is quantitativel analyzed according to cluster analysis and multiple linear regression model.Based on the analysis of influencing factors of groundwater dynamic types and the calculation of water balance in Yinchuan Plain,the water supply on the Profile is analyzed,and the main sources of recharge are: field irrigation,infiltration and channel infiltration,To the main drainage ditch,artificial mining,evaporation and so on.Secondly,the three Profiles mainly develops the groundwater local circulation system and the regional circulation system two groundwater circulation systems.The local groundwater circulation system has shallow depth of development,the horizontal distance is small,the groundwater runoff intensity is strong,the residence time is short,the depth of the groundwater cycle develop Deeply,horizontal distance is large,groundwater runoff is week,with a long residence time.The water flow in each Profile is mainly concentrated in the shallow local groundwater circulation system,calculated by the overall water balance of each Profile.Thirdly,the distribution of ¹⁴ C particle concentration in groundwater is shown by comparison of the ¹⁴ C particle concentration distribution in groundwater,and the distribution of ¹⁴ C particles in groundwater is similar to that of groundwater radioactive isotope The results show that the model of groundwater ¹⁴ C solute transport has a certain reliability,and the distribution of groundwater age on the profile can be guided by the model.The age of the Profile is mostly below 60 a,and the age distribution of confined water from top to bottom and rom west to east is becoming older and older,and the age range is 2 20 Ka.Fourthly,the salinization degree of groundwater and the type of hydrochemicals in the Profile are obviously zoned along the radial route.The mineralization degree of groundwater in the central and western part of the Helan Mountain is similar to that in the single diving area near the Helan Mountain,and the mineralization degree of the underground water is gradually increasing from east to east.The water chemistry type is mainly becoming from type of HCO3·SO4 to type of Cl·SO4.