A Numerical Model for Simulating Sharp - Interface of Seawater Intrusion in Aquifer - Aquitard Systems

• Main Authors: Chang,Hsiu-Chi, 張修齊
• Other Authors: Hsu,Nien-Sheng
• Format: Others
• Language: zh-TW
• Published: 1993
• Online Access: http://ndltd.ncl.edu.tw/handle/54160737567736875603

碩士 === 國立臺灣大學 === 土木工程研究所 === 81 === A regional numerical model is developed for the simulation of transient seawater intrusion in two-layer coastal aquifers in this research. According to the theory of groundwater flow and seawater intrusion, the model can be applied to locate the position and shape of interface in two-layer aquifers seperated by an aquitard. The sharp interface assumption which assumes seawater and fresh water are not mixed is adopted here. The Dupuit assumption and vertical integral are used to simplify the 3-D mathematical model which is difficult to solve. The combining governing equations of seawater and fresh water in each aquifer are flow equations of groundwater. The Hubbert's equation is used to couple seawater and fresh water in each aquifer. The numerical model adopts the Picard's Iteration Method to linearize the nonlinear equations. The Galerkin Finite Element Method and the Finite Difference Method are used to discretize the space domain and time domain to form matrix equation, and the matrix solver is the Conjugated Gradient Method. The exact analytical solution of four examples are presented to verify the numerical model. The discrepancy between the Ghyben - Herzberg equation and Hubbert equation is also discussed in this research. The results are compared very favorably or consistent with the physics.