Simulation of the Fate of Contaminant in Groundwater under Uncertainty Using Optimized Linear Interpolation

Abstract

Subsurface characterization is an important requirement in developing a simulation model of the processes of subsurface contaminant transport and degradation. This paper presents a methodology that can model the inherent uncertainty that arises due to simplification of the processes and assumptions made about site data. The linear interpolation method was adopted to represent the changes in the hydraulic characteristics under study at uncertain locations within the subsurface site. An optimization method was designed to identify the proper range of those uncertain locations within which the hydraulic characteristics were assumed to change. A 3D contaminant fates and transport simulation model - UTCHEM (University of Texas at Austin, 2000) was used in this study to predict the site status. The solution method for this nonlinear optimization function was the multi-level cubic spline function. Results from the multi-level cubic spline function were compared with results generated from the fitting polynomials in the 6th and 9th orders. This method was used to analyze some data from a laboratory experiment. The results indicated that the optimized linear interpolation function can model this kind of uncertainty and enhance accuracy of the simulation model.

Keywords: Cubic spline function, optimized linear interpolation, simulation