| Summary: | 碩士 === 國立臺灣大學 === 生物環境系統工程學系暨研究所 === 90 === Due to the rapid development of numerical analysis and computer, scholars employ mathematical model to simulate the groundwater flow, a complex physical phenomenon. Most of the geological parameters in the model are acquired from laboratory experimentation or pumping test. However, these parameter values obtained will vary during application as a result of the disturbance and limit of the soil sample. Therefore, the purpose of this article is to inversely evaluate the parameters of model and pumping rate by observing the groundwater stage in a simulated region.
This study is basis on the following assumptions：(1)The two-dimensional confined aquifer is used as the governing equation. (2) Using the Finite Element Method of triangular element to solve the governing equation. (3) Dividing into n polygonal cells, each cell owns transmissivity and storativity itself, it is homogeneous and isotropic. (4) Each node is established observation well that is known information of potential. “m” is the number of node and will get the m known potentials per time step.(5) To establish pumping wells for nodes within the boundaries.(6) Boundary flux are evaluated by using point source flux.(7)Boundary condition must be known.(8)Assuming pumping rate and boundary flux are independent of time.
A linear system can be obtained by solving the governing equation using the Finite Element Method. In the solving process, determine whether there exists one unique solution according to the rank of coefficient matrix. If the matrix contains interdependent equations, pumping test can be applied. After obtaining the values of transmissivity and storativity in part of the region, continue solving the equation. Use the examples in this paper to inversely evaluate the values of transmissivity, storativity and pumping rate. By comparing these values obtained from inverse evaluation with that from normal evaluation, the error is within a 10% range, which confirms the reliability and feasibility of the method proposed in this paper.
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