Data/hora: 16/06/2024 06:22:59

Biblioteca(s): | Embrapa Solos.
Data corrente: | 22/11/2002
Data da última atualização: | 22/11/2002
Autoria: | GOMEZ HERNANDEZ, J. J.
Título: | A stochastic approach to the simulation of block conductivity fields conditioned upon data measured at a smaller scale.
Ano de publicação: | 1991
Fonte/Imprenta: | Stanford: University of California-Department of Earth Sciences, 1991.
Páginas: | 351p.
Idioma: | Inglês
Notas: | Ph.D.Thesis
Conteúdo: | Two methods are proposed fo the direct generation of block conductivities condinoned upon data measured at a smailer scale. These methods allow Monte-Carlo analyses of aquifer response variables up to 125 times faster than more traditional methods that do not directly generate block conductivities. The first method is analytical and is limited to two dimensional spaces with small, isotropic variability of the logarithms of hydraulic conductivity and uniform how in unbounded aquifers. The second method is numerical and is not restricted by the previous conditions although it is limited to a finite-difference formulation of the groundwater flow equation with blocks of a single size. Both methods call for efficient stochastic conditional simulation algorithms and for accurate methods to scale-up hydraulic conductivities. Regarding conditional simulations, the novel sequential simulation algorithm was fully implemented for the first time for the generation of both Gaussian and non-Gaussian random fields, with direct conditioning to local data. This algorithm was also applied for the first time to the co-simulation of several variable with a joint Gaussian multivariate distribution. Regarding the scaling-up problem, two approaches are proposed an analytical one under the same aforementioned assumptions and a numerical one not limited by these assumptions. The methodology proposed is applied to a Monte-Carlo analysis of flows in a synthetic aquifer. The results are compared to a reference Monte-Carlo analysis implemented at the smallest scale. In addition these results are compared with those obtained from the more traditional approach consisting of generating conductivity fields as the small-cale and then scaling-up each block using a within-block flow simulation. The reproduction of the results obtained from the reference analysis at the smallest scale is shown to be good with the proposed technique being faster CPU wise than either the refence analysis or the traditional methods.
Categoria do assunto: | --
Registro original: | Embrapa Solos (CNPS)
Exemplares: | CNPS - (7738-1) - ADC - TS - -- - 91019 - GOM/91 - 1998.00045 - DIS