Tracing the Spatial Distribution of Whole-Lake Exchange of Groundwater and Lake Water in Low-Hydraulic Gradient Systems Using δ18O and Electrical Conductivity and Uncertain End-Member Mixing Analysis

摘要: δ18O and electrical conductivity (EC) were used successfully to trace the spatial distribution of whole-lake groundwater-lake exchange for a small (four ha) groundwater-fed lake situated in low relief hydraulic gradient area. The method relies on quick sampling shallow groundwater, direct analysis EC field, relatively in-expensive laboratory. Ternary uncertain end-member mixing (precipitation, water) quantified composition water discharging recharging from lake. tracer agreement with interpreted groundwater flow near use only one (either or EC) gave same results recharge segments, but discharge segments changed origin being precipitation controlled. two tracers complemented each other, especially different signals groundwater. end-members assessed based local (groundwater off-site (precipitation) data. data found be useful if it contained representative information local-site seasonality (uncertainty, variance). Final concentrations could explain transience hydrology at site (i.e., flooding area adjacent during periods high precipitation, variability signal precipitation). This methodology potentially represents new option study systems. collected over days is by itself developing next steps like quantification fluxes other standard methods (Darcy approach, seepage meters, temperature). can provide quantitative estimation inputs outputs using analysis.