STUDIES OF WATER SENSITIVITY OF THE POROUS MEDIA ATSALINE WATER-FRESHWATERINTERFACE

摘要

Based on the geohydrological investigation in the fields, seawater and freshwater were respectively made to flowrnthrough a plexiglass column filled with samples from the downstream of the Dagu River. Water sensitivity at saline water-freshwaterrninterface was discussed by changing salinity sharply and gradually. The results showed that the permeability of porous mediarndecreased by 50.0% when seawater was flushed by freshwater. However, the decrease of permeability was comparatively slow andrnthe permeability decreased by 25.1% in the case of gradual salinity decrease. The faster the rate of salinity decreased, the larger thernreduction degree of the permeability was. A significant decrease of hydraulic conductivity was observed with time and the decreasernwas irreversible. Due to rapid salinity reduction of the influent, the migration and interception of the released clay particles such asrnillite, kaolinite and chlorite resulted in the permeability change.