Estimation of spatio-temporal groundwater recharge in Jeju Island, Korea

Accurate estimation of groundwater recharge in Jeju Island, which relies on groundwater for most of its water use, is very important for water resource management and planning. However, Jeju watershed is a volcanic island with high permeability, ephemeral streams and mountain areas, so it is difficult to estimate the hydrological components using existing hydrological models. To overcome these limitations, SWAT-K (Soil and Water Assessment Tool-Korea), which can simulate ephemeral stream and threshold runoff, was used to estimate hydrological components (such as precipitation, evapotranspiration, runoff, and groundwater recharge) of Jeju watershed (~1,828 km²). The overall procedure of SWAT-K modeling (model setup, calibration and validation) was performed from 1991 to 2020. The simulated and observed daily streamflows were compared and showed a good agreement. In particular, a reasonable estimation of groundwater recharge was confirmed through the comparison of simulated groundwater recharge and the observed groundwater level. Finally, the spatio-temporal groudwater recharge characteristics were analyzed using the SWAT-K results.

Acknowledgement : Research for this paper was carried out under the KICT Research Program (project no.20220275-001, Development of coastal groundwater management solution) funded by the Ministry of Science and ICT.