A Monte Carlo-Based Approach for Groundwater Chemistry Inverse Modeling
A Monte Carlo-Based Approach for Groundwater Chemistry Inverse Modeling作者机构：Kennedy/Jenks Consultants San Francisco USA
出 版 物：《Open Journal of Modern Hydrology》 (现代水文学期刊（英文）)
年 卷 期：2014年第4卷第4期
页 面：112-120页
学科分类：1002[医学-临床医学] 100214[医学-肿瘤学] 10[医学]
主 题：Inverse Model Geochemical Model Monte Carlo Simulation
摘 要：Inverse geochemical modeling of groundwater entails identifying a set of geochemical reactions which can explain observed changes in water chemistry between two samples that are spatially related in some sense, such as two points along a flow pathway. A common inversion approach is to solve a set of simultaneous mass and electron balance equations involving water-rock and oxidation-reduction reactions that are consistent with the changes in concentrations of various aqueous components. However, this mass-balance approach does not test the thermodynamic favorability of the resulting model and provides limited insight into the model uncertainties. In this context, a Monte Carlo-based forward-inverse modeling method is proposed that generates probability distributions for model parameters which best match the observed data using the Metro-polis-Hastings search strategy. The forward model is based on the well-vetted PHREEQC geochemical model. The proposed modeling approach is applied to two test applications, one involving an inverse modeling example supplied with the PHREEQC code that entails groundwater interactions with a granitic rock mineral assemblage, and the other concerning the impact of fuel hydrocarbon bioattenuation on groundwater chemistry. In both examples, the forward-inverse approach is able to approximately reproduce observed water quality changes invoking mass transfer reactions that are all thermodynamically favorable.
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