Stochastic groundwater flow models in confined and leaky aquifers
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Date
2019-06
Authors
Amakali, Sarti Rautia
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Publisher
University of the Free State
Abstract
This dissertation proposes an application of stochastic modeling of groundwater flow in confined and leaky aquifers. We are estimating that aquifer parameters such as transmissivity, storativity and leakage factor vary, not constant, in space at different period especially in heterogeneous environment. Heterogeneous environment are known to be complex because of their uncertainty. Uncertainty referred in modeling includes errors in dataset, which might be bias or variance (under fitting/over fitting), low or not enough data, or unbalanced data, which all affect the model produced if not captured with appropriate model technique. The groundwater flow equation for confined and leaky aquifers derived by the latest version Atangana and Ramotsho, as well asAtangana and Mathobo, which all include scaling matrix of the soil, are considered and further modified to a new scheme of stochastic models for confined and leaky aquifer. We tried to achieve the capture statistical setting of aquifer parameters using the concept of stochastic modeling technique. The aquifer parameters are replaced by distribution for instance, Gaussian or normal distribution.Due to the complexity of the modified models, it is almost impossible to obtain the exact solution by using analytical solution, thus we opt to numerical analysis, in particular the Newton method used to derive the numerical solutions of the modified models. Detailed analysis of stability and convergences, we used method are presented for both models. Numerical simulations are depicted for different distributions.
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Keywords
Dissertation (M.Sc. (Geohydrology))--University of the Free State, 2019, Arithmetic mean, Complex environment, Confined aquifer, Crank Nicholson, Deterministic, Discretization, Distribution, First order derivative, Geometric mean, Groundwater flow model, Harmonic mean, Heterogeneity, Leakage, Leaky aquifer, Newton method, Numerical simulation, Second order derivative, Stability, Statistic, Steady state flow, Stochastic model, Storativity, Transmissivity, Unsteady state flow