| Abstract: | Laplace transform step-response functions are presented for various homogeneous confined and leaky aquifer types and for anisotropic, homogeneous unconfined aquifers interacting with perennial streams. Flow is one-dimensional, perpendicular to the stream in the confined and leaky aquifers, and two-dimensional in a plane perpendicular to the stream in the water-table aquifers. The stream is assumed to penetrate the full thickness of the aquifer. The aquifers may be semi-infinite or finite in width and may or may not be bounded at the stream by a semipervious streambank. The solutions are presented in a unified manner so that mathematical relations among the various aquifer configurations are clearly demonstrated. The Laplace transform solutions are inverted numerically to obtain the real-time step-response functions for use in the convolution (or superposition) integral. To maintain linearity in the case of unconfined aquifers, fluctuations in the elevation of the water table are assumed to be small relative to the saturated thickness, and vertical flow into or out of the zone above the water table is assumed to occur instantaneously. Effects of hysteresis in the moisture distribution above the water table are therefore neglected. Graphical comparisons of the new solutions are made with known closed-form solutions.Laplace transform step-response functions are presented for various homogeneous confined and leaky aquifer types and for anisotropic, homogeneous unconfined aquifers interacting with perennial streams. Flow is one-dimensional, perpendicular to the stream in the confined and leaky aquifers, and two-dimensional in a plane perpendicular to the stream in the water-table aquifers. The stream is assumed to penetrate the full thickness of the aquifer. The aquifers may be semi-infinite or finite in width and may or may not be bounded at the stream by a semipervious streambank. The solutions are presented in a unified manner so that mathematical relations among the various aquifer configurations are clearly demonstrated. The Laplace transform solutions are inverted numerically to obtain the real-time step-response functions for use in the convolution (or superposition) integral. To maintain linearity in the case of unconfined aquifers, fluctuations in the elevation of the water table are assumed to be small relative to the saturated thickness, and vertical flow into or out of the zone above the water table is assumed to occur instantaneously. Effects of hysteresis in the moisture distribution above the water table are therefore neglected. Graphical comparisons of the new solutions are made with known closed-form solutions. |
| Genre: | Article |
| ProdID: | 70022295 |
| Citation Author: | Moench, A. F.; Barlow, P. M. |
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| Citation End Page: | 210 |
| Citation Issue: | 3-4 |
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| Citation Language: | English |
| Citation Larger Work Title: | Journal of Hydrology |
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| Citation Number Of Pages: | 19 |
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| Citation Publisher: | Elsevier Science B.V. |
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| Citation Search Results Text: | Aquifer response to stream-stage and recharge variations. I. Analytical step-response functions; 2000; Article; Journal; Journal of Hydrology; Moench, A. F.; Barlow, P. M. |
| Citation Start Page: | 192 |
| Citation Volume: | 230 |
| Citation Year: | 2000 |
| Type: | citation/reference |
| Text: | Aquifer response to stream-stage and recharge variations. I. Analytical step-response functions; 2000; Article; Journal; Journal of Hydrology; Moench, A. F.; Barlow, P. M. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| URL (DIGITAL OBJECT IDENTIFIER): | http://dx.doi.org/10.1016/S0022-1694(00)00175-X |
| Date Other: | Sat, 1 Jan 2000 00:00 -0600 |
| Publisher: | Elsevier Science B.V. |
