Stream Depletion and Pumping Test Interpretation in a Horizontally Anisotropic Aquifer Near a Stream

Conventional pumping test theories such as Theis solution often assume a horizontally isotropic media. Horizontal anisotropy exists in certain aquifer settings and its impact on pumping tests is not clearly demonstrated before, particularly when the aquifer is bounded by a stream. In this thesis, based on a newly developed mathematical model for pumping tests in a horizontally anisotropic aquifer bounded by a stream, the corresponding interpretation procedures will be illustrated. Stream depletion will be calculated as a result of stream bank pumping based on the new model as well. The results of this research reflect that (1) aquifer parameters derived from newly developed interpretation methods are acceptable in the range of allowable error; so these methods can be used in practical field experiment; (2) with the increase of Ta/Tb, stream depletion rate under the steady state also increases where Ta and Ta are the major and minor principal transmissivity values ( Ta>Tb); (3) when the angle between the X axis and the direction of Ta increases from 0 to pi/2, stream depletion increases, where the X-axis is one of the working coordinate; conversely, when such an angle increases from pi/2 to pi, stream depletion decreases. This research is expected to fill the gap of knowledge on present stream-aquifer interaction and pumping test theories for aquifers