Reconstructing paleohydrological conditions in Lake Kasumigaura during a Holocene using unsteady groundwater flow simulation

Abstract

In Lake Kasumigaura where paleohydrologic information during the period of sedimentation may have remained, two-dimensional unsteady groundwater flow simulation was made in vertical cross section while considering such long-term transitions as sea level change, changes in salinity and sedimentation. As a result, the depth profiles of salinity in pore water extracted at two core drilling sites that were obtained in existing works were reproduced, the difference in contribution of local fresh groundwater at both sites was indicated. The simulation revealed that Site K-1, which is close to the lakefront, was affected by local fresh groundwater as well as surface water, but Site K-2, some way distant from the lakefront, was unaffected by the local fresh groundwater. By unsteady groundwater flow simulation, the transition of the more detailed hydrological environment was revealed.