A mathematical model solved by ADIP method is used to study the dynamic behavior of Shiroishi area aquifer, Saga Prefecture, Kyushu, Japan, in response to pumping from irrigation and municipal wells, where subsidence has been resulted due to heavy pumping. The two dimensional model with constant hydraulic head boundaries (where the head has not been changed) were used to compute the seasonal drawdowns and these computed drawdowns were compared with field data. The drawdown contours of September were found in good agreement with field data, but of February showed low drawdowns. It was thought that the irrigation period is from May to September, so the recharge was cut off after September and in doing this way the computed and field contours were found in good agreement, thus the recharge occurs in the irrigation period only. In this study the qualitative relationships among drawdown, subsidence and thickness of clay layer were determined and it was concluded in the following way: For same drawdown, the subsidence is higher for thicker clay layer, and for constant thickness, the subsidence increases with increase in drawdown.