A Model to Simulate Pumping Tests in Wells with High Loss and Backflow
Article first published online: 31 AUG 2010
Copyright © 2010 Saudi Aramco. Journal compilation © 2010 National Ground Water Association
Volume 49, Issue 3, pages 445–449, May/June 2011
How to Cite
Kawecki, M. W. (2011), A Model to Simulate Pumping Tests in Wells with High Loss and Backflow. Groundwater, 49: 445–449. doi: 10.1111/j.1745-6584.2010.00747.x
- Issue published online: 25 APR 2011
- Article first published online: 31 AUG 2010
- Received December 2009, accepted July 2010.
Traditional methods of analyzing pumping tests in single wells fail when the well loss is very high due to a low transmissivity skin. Because of the restricted rate at which water can enter a high loss well from the aquifer, well casing storage becomes a significant factor. Additionally, if a slug of water enters the well from the pump column immediately after the pump is switched off, it has a long-lasting significant effect on the recovering water level in the well because it cannot be absorbed rapidly by the aquifer. A theoretical model is derived here that simulates the water level in a well in these circumstances. In the model, the continuously changing rate of water inflow from the aquifer to the well is approximated by a step function with a finite difference time step. It is demonstrated by a real example that the model can be applied easily to analyze pumping tests, including tests with a varying pumping rate. The analysis confirms suspected high well loss, calculates the unknown rate of backflow, and determines the aquifer's transmissivity.