Estimation of quantitative spatial and temporal distribution for groundwater storage in agricultural basin of Korea: implications for rational water use

Assessment of spatio-temporal variability in groundwater storage (GWS) is critical for effective water resource planning and management with rational groundwater use. Haean Basin comprising 64 km2 area, mainly depends on groundwater for agricultural, domestic and other water uses. For quantification of GWS variability, sufficient field-based hydrological data of the ongoing decade (2011–2017) were interpolated in ArcGIS, to give reliable results. Despite satellite remote sensing having advantages in the field of hydrology, the limitation of accessibility at larger spatial resolution (~ 200,000 km2) is making it non-applicable for fine-scale observations. From the surface area, saturated thickness and specific yield of aquifer, a decline of 33 million cubic meters in GWS volume was indicated from 230 to 197 during the observed 6 years. An observable drop (4.6 m) in the mean water level due to increased water use (0.49 MCM) during this decade is responsible for the change in the mean groundwater level. A changing water level can change the surface area and saturated thickness of aquifer that have a positive correlation with GWS, and act as main controlling factors for GWS change. An annual recharge of 0.14 m to the total amount of GWS is near negligible, considering the long-term sustainability of groundwater resource. A shift towards more use of surface water, and limited drilling of groundwater wells is recommended for rational water use. The findings of this study will provide basic knowledge for relating studies, specifically which are based on small (local) scale distribution of groundwater resource.