Groundwater can flow into or out of surface water and thus can greatly affect the quantity and quality of surface water. In this study, we conducted a water quantity and quality analysis for 11 months in 2018 and 2019 to evaluate the temporal contribution of groundwater to surface water at Osongji, a small lake located in Jeonju-si, Jeollabuk-do, Korea. Groundwater fluxes and groundwater and surface water levels were measured using seepage meters and a piezometer, respectively. On-site water quality parameters, cations, and anions for groundwater and surface water were analyzed. Hydrogen and oxygen isotopes for groundwater, surface water, and rainwater were also analyzed. Groundwater influx did not correlate directly to precipitation, suggesting that it may be delayed after rainwater infiltration. Aqueous chemistry indicated that the hydrogeochemical characteristics of surface water were substantially affected by groundwater. The isotopic composition of surface water changed over time, indicating a different contribution of groundwater in different seasons. This study shows that water quantity and quality data can be used in combination to evaluate temporal changes in the groundwater contribution to surface water.
Groundwater in the polar region interacts closely with surface water and plays an important role in maintaining the surrounding ecosystems.In polar regions, groundwater flows are restricted in the active layer, a dynamic variably-saturated zone depending on temperature changes.In order to quantify the groundwater flow system in the polar region, it is important to estimate the hydraulic and thermal properties of the active layer.In this study, the hydraulic and thermal properties of the active layer in the Barton Peninsula, Antarctica were evaluated through laboratory column experiments and numerical modeling.Sediments from two lakes near King Sejong Station, which show differences in ecological and geological conditions, were collected and used for the experiments.The two soil samples were sieved to 2 mm and packed in cylindrical acrylic-columns with the same height of 52 cm.A total of five temperature and moisture sensors were installed into each column with an interval of 10 cm to measure the temperature and moisture content at each layer.Saturationdrain tests, permeameter tests, and freeze-thaw tests were performed to derive hydraulic parameters (i.e., K s , θ s , S wr , α, β, and S s ) and thermal diffusivity (D).The parameters were estimated by inverse modeling with HydroGeoSphere (HGS), combined with Parameter ESTimation (PEST).Based on the analysis results, the saturated hydraulic conductivities (K s ) of the two Antarctic soils were dependent on the grain size distribution, and it affected the van Genutchen parameters α and β [1], which are essential parameters for quantifying the variably-saturated flow.The thermal diffusivities of the soil samples were 4.64 and 0.65 cm 2 /min, and their differences were caused by differences in the lake environments such as organic matter contents and porosity.The results from this study can provide a basis for future studies regarding the surface water-groundwater interactions in Antarctica, which are affected by the freeze-thaw processes resulting from climate change.
To better understand the changes in the hydrologic cycle caused by global warming in Antarctica, it is crucial to improve our understanding of the groundwater flow system, which has received less attention despite its significance. Both hydraulic and thermal properties of the active layer, through which groundwater can flow during thawing seasons, are essential to quantify the groundwater flow system. However, there has been insufficient information on the Antarctic active layer. The goal of this study was to estimate the hydraulic and thermal properties of Antarctic soils through laboratory column experiments and inverse modeling. The column experiments were conducted with sediments collected from two lakes in the Barton Peninsula, Antarctica. A sand column was also operated for comparison. Inverse modeling using HydroGeoSphere (HGS) combined with Parameter ESTimation (PEST) was performed with data collected from the column experiments, including permeameter tests, saturation-drain tests, and freeze-thaw tests. Hydraulic parameters (i.e., Ks, θs, Swr, α, β, and Ss) and thermal diffusivity (D) of the soils were derived from water retention curves and temperature curves with depth, respectively. The hydraulic properties of the Antarctic soil samples, estimated through inverse modeling, were 1.6×10-5 ~ 3.4×10-4 cm s-1 for Ks, 0.37 ~ 0.42 for θs, 6.62×10-3 ~1.05×10-2 for Swr, 0.53 ~ 0.58 cm-1 for α, 5.75 ~ 7.96 for β, and 5.11×10-5 ~ 9.02×10-5 cm-1 for Ss. The thermal diffusivities for the soils were estimated to be 0.65 ~ 4.64 cm2 min-1. The soil hydraulic and thermal properties reflected the physical and ecological characteristics of their lake environments. The results of this study can provide a basis for groundwater-surface water interaction in polar regions, which is governed by variably-saturated flow and freeze-thaw processes.
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