Geospatial patterns in surface water parameters and recent land use change in the karst of Samcheok, South Korea

Karst landscapes develop distinct surface landforms intricately connected to a more complex subsurface drainage system due to the highly soluble nature of its bedrock. Because of this, surface processes can more directly affect the groundwater system through conduits such as caves and sinkholes. Due to high hydraulic conductivity, aside from surface and groundwater, the soil produced from weathering and erosion of karst is also affected. Samcheok, found in southeastern Gangwon Province, is an example of an area that is underlain by limestone-bearing formations, allowing the formation of karst. In this study, the patterns in the hydrochemical characteristics of surface water and the land use of areas adjacent to the streams in Samcheok karst were explored through geospatial analyses. Additionally, recent land use change in the area was also investigated. Surface waters from four streams in Samcheok were analyzed: Osipcheon River, Yeosam Stream, Sohan Stream, and Gyogok River. Results show that hydrochemical parameters in northeast Samcheok karst are mostly varied and to an extent dependent on the stream where the samples were taken from more than the sampling distance from the coast. Usual patterns for pH and dissolved oxygen in terms of salinity were not observed. Concentrations of cations and anions mostly varied between the two sampling seasons (winter and spring for February and April 2020 samples, respectively) and were also varied in terms of linear correlation for concentration vs. distance to stream outlet graphs. High linear correlation was observed for spring samples from Gyogok River for the following ions: Ca²⁺ (R² = 0.976), Mg²⁺ (R² = 0.9321), SO₄^2- (R² = 0.879), and HCO₃^- (R² = 0.955). More than 50% of the area adjacent to streams is classified as “other bare land”. Between 2019 and 2020, there was an increase in the total land area for coniferous forests and a decrease in mixed forest and undeveloped arable field. Research on geospatial patterns for hydrochemical parameters and land use change in environments susceptible to pollution such as karst areas are useful for land use planning and erosion studies. This research was funded by the Basic Science Research Program through the National Research Foundation of Korea funded by the Ministry of Education (Nos. 2019R1I1A2A01057002, and 2019R1A6A1A03033167) and the Korea Ministry of Environment as "The SS (Surface Soil conservation and management)” project (No. 2019002820004).