1979 年 33 巻 2 号 p. 73-84
The groundwater flow simulation model provides a mean of achieving the groundwater basin management. The unit-basin model at the initial stage was revised to the quasi-three dimensional model and the vertical two dimentional model. While applying these models to field problems, the authors considered in practical request that the simulation model should be revised to a quasi-three dimensional multiaquifer (QTDM) model and also to a three-dimensional model. Then, a QTDM model was offered which computes explicitly the vertical flow in the aquitard using one-dimensional finite element method. The advantage of this method lies in the reduction of computing time and storage in compassion with the QTDM model by FUJINAWA (1977b) which computes vertical leakage implicitly. In addition, a three-dimensional model was provided which solves the equation of three-dimensional unsteady confined flow using finite elements. Numerical results of these three models are compared to the analytical solution obtained by HANTUSH (1960) and to the one assessed by NEUMAN & WITHERSPOON (1969). Except at large value of the β factor of Hantush, numerical results give good agreement with the analytical solutions. The QTDM model by the authors provides no error caused by the explicit computation of the vertical leakage, therefore the applicability of this model is established. At large value of the β factor and at small values of time, the difference between numerical results and the analitical solution is great, because only one element is used to incorporate the vertical flow through the aquitard. However three-dimensional model which has a number of nodes in the aquitard requires long computing times and large storage, it is effective to obtain accurate results at small values of time.