Thesis
An analytical and numerical investigation of stream/aquifer interaction methodologies
Washington State University
Master of Science (MS), Washington State University
2011
Handle:
https://hdl.handle.net/2376/104726
Abstract
Groundwater and surface water interaction at the stream/aquifer interface produces both local and regional flow patterns that govern the behavior in many groundwater flow systems. Fluctuations from flood waves cause rapid changes in surface water level and play an important role in the transfer of water from the river to the aquifer. Studying an artificial flood wave from the Post Falls Dam during the low flow summer months in the Spokane Valley Rathdrum Prairie (SVRP) aquifer has provided insights on how the method used to describe the interaction affects the heads and seepage rates produced by the flood wave. A data set capturing six-minute intervals as the flood wave passed both in the river and in thirty observation wells in the SVRP aquifer will be used for calibration. Three analytical solutions and two numerical solutions where used to simulate the changes in groundwater head or seepage or both, from the Spokane River to the SVRP aquifer. The three analytical solutions use convolution integrals to simulate the flood wave and solve head in the aquifer or flow in the river in one or two dimensions. The two numerical solutions also use difference approaches; finite difference and finite element. The former models the nonlinear Boussinesq equation and the latter the Richards equation. The results show that each analytical solution produced different values of the hydraulic conductivity of the riverbed sediments, ranging 1.05-29 ft/day. Due to limitations of the assumptions in the analytical models Sy was allowed to increase only to 0.3. The numerical models also produced different estimates of streambed hydraulic conductivities with MODFLOW values 71-75% lower than HYDRUS values of 1.09 and 0.76 for areas 1 and 2 respectively. These results show that the solution method chosen is important in the resulting calibrated values.
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Details
- Title
- An analytical and numerical investigation of stream/aquifer interaction methodologies
- Creators
- Colt William Shelton
- Contributors
- Michael E. Barber (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Civil and Environmental Engineering, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; Pullman, Wash. :
- Identifiers
- 99900525274801842
- Language
- English
- Resource Type
- Thesis