Using Jacob’s Method to Discuss the Influences of Spatial Heterogeneous Field on Pumping Tests

• Main Authors: Yu-Wen Fang, 方昱文
• Other Authors: 譚義績
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/32006422630480138728

碩士 === 國立臺灣大學 === 生物環境系統工程學研究所 === 96 === The purpose of this study is to estimate representative aquifer parameters via drawdown data collected during pumping tests in heterogeneous fields. Jacob approximation and Theis method are reexamined along with Best-fit methods for pumping test analysis. The objects include；(1)searching for the representative average for aquifer parameters under different hydraulic gradients, (2)examining if the Jacob approximation and Theis method remain available in heterogeneous fields for estimating representative parameters, (3)comparing the differences between the estimated parameters and the effective transmissivity, (4)differentiating the estimates derived from pumping tests and natural flow of radial flow and parallel flow respectively, and then discussing the results derived under different variances and pumping rates. A numerical model, VSAFT2, is used to simulate the aquifer tests to derive effective transmissivities under different conditions. The results showed that the effective transmissivities come most closely to the generated points’ geometric mean. Transmissivities estimated by Jacob approximation and Theis method under radial flow are representative in homogeneous field, however, the deviation may increase with variance thus decrease the describing abilities for actual characteristics. The relation between the distance from observation point to pumping well and the best-fit section is not able to be developed so far. It can be found that a high percentage of the best-fit sections fall at u=0.01~0.02 though there’s not an obvious trend to determine the representative transmissivities according to the pumping test data.