Analytical model for non-Darcian flow toward a partially penetrating well due to constant-rate pumping in a fractured confined aquifer

• Main Authors: Chung, Yu, 鍾渝
• Other Authors: Yeh, Hund-Der
• Format: Others
• Language: en_US
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/pk3h2q

碩士 === 國立交通大學 === 環境工程系所 === 106 === This study presents a mathematical model for describing the drawdown distribution to analyze non-Darcian flow for constant-rate pumping at a partially penetrating well in a fractured confined aquifer of infinite extent. The model is developed based on the double-porosity concept combined with a linearized non-Darcian flow approach using Izbash’s law. The solution of the model in Laplace domain is derived via the methods of finite Fourier cosine transform and Laplace transform. The time-domain results are numerically evaluated by the Crump scheme. Both large-time and small-time solutions for transient flow are derived based on the convolution theorem and the Bromwich integral and the steady-state solution is also developed. The existing solutions for non-Darcian flow are shown to be special cases of the present solution. The solution is then compared with the finite difference solution to verify its correctness. Also, the comparison between the present solution and exiting solution for Darcian flow reveals that the fluid exchange from the matrix blocks to the fractures occurring in the intermediate time. The effects of exchange coefficient and non-Darcian factor on the temporal drawdown are examined. Moreover, the sensitivity analysis is performed to investigate the drawdown behavior in response to the change in each of the hydraulic parameters. Finally, the present solution is coupled with the Levenberg-Marquardt algorithm to analyze two sets of field measured data for estimating the hydraulic parameters. This present solution is a useful tool in predicting the non-Darcian flow in fractured confined aquifers and determining the aquifer hydraulic parameters for double-porosity media.