Impact of rising air temperature on groundwater temperature in Korea

초록

Groundwater constitutes the largest reservoir of unfrozen freshwater globally, offering broader accessibility. Consequently, groundwater is in high demand as a resource for irrigation and serves as a significant source of drinking water. Preserving both the quality and quantity of groundwater is therefore a major concern, and groundwater temperature is one of the key factors influencing these attributes. However, compared to surface water, the impact of rising air temperatures on groundwater thermal regimes has not been sufficiently investigated. This study aims to assess the influence of increasing air temperature on groundwater environments by analyzing long-term groundwater temperature data (1996-2022) from 25 monitoring wells across seven metropolitan cities in Korea (Seoul, Incheon, Daejeon, Daegu, Ulsan, Busan, and Gwangju), along with corresponding air temperature data obtained from Korea Meteorological Administration stations. The magnitude and statistical significance of trends in annual mean, maximum, and minimum groundwater and air temperatures were determined using linear regression and the Mann-Kendall test, respectively, while their interrelationship was quantified with Pearson correlation. The analysis revealed an overall increasing trend in groundwater temperatures, with observed warming rates ranging from 0.04 to 1.58 degrees C per decade. Notably, the most pronounced increase was observed in the minimum groundwater temperature. These findings provide empirical evidence that groundwater warming is not a prospective threat but a contemporary phenomenon, underscoring the necessity of revising national strategies for sustainable water resource management in the context of a changing climate.

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