Using multiple tracers to quantify groundwater discharge to Yellow river in Weining plain

It is important to quantify the hydraulic relationship between surface water and groundwater for developing water resources sustainably. In this study, thirty-six samples were taken and the interaction between river water and groundwater was analyzed on the basis of hydrogeochemical characteristics. Environment tracers such as EC and Cl- were used to calculate groundwater inflows along river flow path by the mass balance method, then it provided a detailed longitudinal profile of groundwater discharge rates. The results show that groundwater discharged to Yellow River mainly in dry season and varied spatially along river length with larger rates in two areas. The groundwater inflows calculated by Cl- and EC mass balances differentiated with each other, which indicated potential uncertainties. Thus, it was necessary to use multiple tracers to quantify groundwater discharge in order to improve accuracy. The representation of the groundwater end-member for environment tracers, the completeness of water balance items and sample resolution were shown to be of vital importance for calculating groundwater inflows using environmental trace method.