Analysis of terrestrial water storage variations in South Korea using GRACE satellite and GLDAS data in Google Earth Engine

Abstract

With the requirement of a macroscopic approach to understanding the relationship between water resources and hydrological phenomena, such as severe droughts under climate change, this study investigates South Korea’s long-term terrestrial water storage (TWS) using GRACE satellite data. A detailed analysis of water balance in TWS, based on the GLDAS model outputs in Google Earth Engine, reveals the following results: (1) TWS anomaly shows an averaged decrease of -33.5 mm yr−1 from 2003 to 2016. (2) Spatial shifts in TWS anomaly (-1.176 to -0.424 cm) unveil regional water storage dynamics, indicating negative temporal slope changes per grid cell (-0.393 to -0.225). (3) Contributions of precipitation to TWS are not always straightforward, due to runoff inefficiencies affecting water storage and groundwater. (4) Accessible water, integrating surface water and groundwater linked only to the shallow layer’s soil moisture, constrains deep groundwater accounting, emphasizing the need for local groundwater surveys in further research.