ABSTRACT

Groundwater simulation using computer technology has been employed since the 1960s. After the first application of digital computer simulation by Tyson and Weber (1964), a similar groundwater simulation model was applied to the aquifer system in the western part of Tokyo by Shibasaki et al. (1969). The model was called a horizontal two-dimensional model, but the leakage term from the upper unconfined aquifer through the upper confining layer was taken into account in the model considering the hydrogeological settings of the Musashino Terrace in western Tokyo. In the 1970s, serious damages caused by land subsidence became significant social problems in Japan (Shibasaki and Research Group for Water Balance, 1995). To simulate occurrence of land subsidence in the Quaternary aquifer system, the quasi-three-dimensional aquifer model (Kamata et al., 1973) was developed. In the model, leakage from the upper confined aquifer and the squeeze from the confining layers were simulated. Based on the simulated heads in the confining clay layer, the clay compaction was calculated using Terzaghi's one-dimensional consolidation theory.