An Estimation of the Amount of Land Subsidence at Muika-machi in Niigata Prefecture by a Quasi Theedimensional Model

Abstract

The land subsidence at Muika-machi and its outskirts was analized by a quasi threedimensional model using finete element method. Parameters were decided by geological data, hydraulic data, pumping volume of groundwater, etc. These data were investigated at the site in detail. Calcutated values of hydraulic head and the amount of land subsidence were in good agreement with measured values. An estimation of future subsidence by this model showed that the zone of the large amount of land subsidence will spread over the whole town. This distribution is quite unlike the conventional pattern which showed that maximum subsidence was located in the northern extremity of this town. This change is caused by the latest increase in wells at the center of this town.