Pedosphere 18(3): 288--303, 2008
ISSN 1002-0160/CN 32-1315/P
©2008 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Non-Darcian flow toward a finite-diameter vertical well in a confined aquifer |
WEN Zhang1,2 , HUANG Guan-Hua1 and ZHAN Hong-Bin3 |
1 College of Water Conservancy and Civil Engineering, China Agricultural University, Beijing 100083 (China). E-mail: wenzhangcau@gmail.com
2 Chinese-Israeli International Center for Research and Training in Agriculture, Beijing 100083 (China)
3 Department of Geology and Geophysics, Texas A&M University, College Station, Texas 77843-3115 (USA) |
| ABSTRACT |
| Non-Darcian radial flow toward a finite-diameter, fully penetrating well in a confined aquifer was analyzed on the basis of the Izbash equation with consideration of the wellbore storage eflect. We derived semi-analytical solutions of drawdown by using the Boltzmann transform, and obtained approximate analytical solutions of the drawdown at early and late times. MATLAB programs were developed to facilitate computation of the semi-analytical solutions. The turbulence factor v which was directly related to the pumping rate appeared to have negligible influence upon the wellbore well function at early times, but imposed significant influence at intermediate and late times. However, the turbulence factor v imposed non-negligible influence upon the aquifer well function during the entire pumping period, provided that the observation point was not suflciently close to the wellbore. Sensitivity analysis indicated that the power index n in the Izbash equation had less influence on the type curves at the face of the pumping wellbore, but had much greater influence upon the well function in the aquifer. As the n values increased, the drawdown in the aquifer decreased at early times and increased at late times. The Boltzmann transformation could only be used in an approximate sense for radial non-Darcian flow problems. This approximation would provide accurate solutions at early times, and introduce small but consistent discrepancies at intermediate and late times for the wellbore well function. |
| Key Words: finite-diameter well, non-Darcian flow, type curves, well function, wellbore storage |
| Citation: Wen, Z., Huang, G. H. and Zhan, H. B. 2008. Non-Darcian flow toward a finite-diameter vertical well in a confined aquifer. Pedosphere. 18(3): 288-303. |
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