Analysis of Dispersion Effects in a Radially Convergent Flow Field
Date Issued
2007
Date
2007
Author(s)
Wang, Wei-Kaung
DOI
zh-TW
Abstract
This study adopted a two-dimensional mathematical model, including constant dispersivity model (CDM) and scale-dependent dispersivity model (SDM), to describe solute transport in a radially convergent flow field. This model was to determine the longitudinal dispersivities, transverse dispersivities and scale-dependent dispersion effects, by fitting breakthrough curves of extraction well and observation well in a field tracer test. Data of three different field convergent radial tracer tests including Fooyin University, Yunlin Universuty of Science & Technology, and George Town field were used to explore the scale dependent effect on longitudinal dispersivities. The results of the longitudinal dispersivities estimated in this study agree with the relation of the product of the Peclet number and the dispersivity/distance ratio (Pe × eL=4). Dispersivity increases with solute transport distance, indicating that the longitudinal dispersivities treated as constants is not suitable in the modeling of solute transport in groundwater systems. The t-test is used to evaluate the means of the breakthrough curves of observation well #4 in Yunlin Universuty of Science & Technology field and observation well #21, 28 in George Town field. The results show that the transverse dispersivities calculated by averaged concentrations of breakthrough curves are similar to those calculated by concentrations of breakthrough curves with various depths under 95 % confidence interval ( p-value > 0.05). Hence, the formation of three tracer tests can be regarded as a homogeneous aquifer. Moreover, the SDM mathematical model is suitable for the analyses of field tracer tests of the homogeneous aquifer.
Subjects
追蹤劑試驗
尺度效應
縱向延散度
橫向延散度
均質含水層
tracer test
scale-dependent effect
longitudinal dispersivities
transverse dispersivities
homogeneous aquifer
Type
thesis
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