Factors causing dynamic variations in the saltwater–freshwater transition zone in a beach aquifer, Mangsang, South Korea

Jun, Seong-Chun; Bae, Gwang-Ok; Lee, Kang-Kun

Factors causing dynamic variations in the saltwater–freshwater transition zone in a beach aquifer, Mangsang, South Korea | Facteurs causant des variations dynamiques dans la zone de transition eau douce–eau de mer dans un aquifère de plage, Mangsang, Corée du Sud Factores que causan variaciones dinámicas en la zona de transición agua dulce–agua salada en un acuífero de playa, Corea del Sur 引起韩国Mangsang海滩含水层海水-淡水过渡区动态变化因素研究 Fatores que causam variações dinâmicas na zona de transição água salgada–água doce num aquífero de praia, Mangsang, Coreia do Sul

2013

Jun, Seong-Chun | Bae, Gwang-Ok | Lee, Kang-Kun

Dynamic variation in the saltwater–freshwater transition zone below a seafront beach in South Korea was investigated with long-term monitoring of the groundwater in relation to the precipitation, wave height, and tide. Correlation, spectral analysis, and regression analysis of monitoring data were performed to deduce the relationships between these factors. The general shape of the transition zone was affected by the seasonal groundwater levels, but temporary fluctuations were predominantly affected by local rising-groundwater-level events. The distinct increases in the groundwater level were closely related to the wave height. Different patterns of electrical conductivity (EC) change were detected in the shallow and deep zones, and these differences indicated that the transition zone was highly dynamic. The EC values at shallow depths were temporarily increased by the wave setup and tidal fluctuations during the rising-groundwater events, but the EC at greater depths was reduced by the seaward or downward movement of the relative freshwater. In exceptional cases, during extreme increases in the groundwater level resulting from seawater flooding, the rapid downward flow of the flooding saltwater through the well bore caused synchronous EC fluctuations at all depths.

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