Spatial and Temporal Variability of Soil Salinity in the Yangtze River Estuary Using Electromagnetic Induction

Soil salt-water dynamics in the Yangtze River Estuary (YRE) is complex and soil salinity an obstacle to regional agricultural production ecological environment YRE. Runoff into sea reduced during impoundment period as result of water-storing process Three Gorges Reservoir (TGR) upper reaches River, which causes serious seawater intrusion. a problem due shallow saline groundwater under intrusion In this research, we focused on temporal variation spatial distribution characteristics YRE using geostatistics combined with proximally sensed information obtained by electromagnetic induction (EM) survey method typical years TGR. The EM proximal sensing was applied perform field Estuary, allowing quick determination quantitative assessment from 2006 2017. We developed mapping coupling limited laboratory data EM. interpreted electrical conductivity constructing linear model between apparent measured 38 device (EC) samples laboratory. Then, converted salt content (soil g kg−1) through established regression based EC. Semivariograms were fitted ordinary kriging interpolation salinity. cross-validation results showed that prediction acceptable. different presented area affected calculated method. near riverbanks coastlines higher than inland. depth revealed high influenced Under long-term Reservoir, hydrological analyzed. Results gradually increased year types