Gelman Site 1,4-Dioxane Groundwater Contamination Plume Modeling and Forecasting

Abstract

Groundwater systems are intrinsically heterogeneous with dynamic spatio-temporal patterns, which cause significant challenges in quantifying and mapping their complex processes. However, accurate forecasting of regional groundwater contamination is commonly needed to identify its spatio-temporal dynamic that helps the public anticipate the timing and severity of potential groundwater quality issues and possibly serve as an early warning system. This study focuses on modeling a plume of 1,4-dioxane originating from the Gelman site beneath the city of Ann Arbor, Michigan. It proposed a novel methodology to consider the spatially and temporally irregular and uncertain nature of groundwater contamination data to analyze the historical trends of dioxane concentration and predict its transportation: 1. A random forest interpolation model was deployed to fill in or extend fragmented time series data gaps among all the monitoring wells; 2. Mann-Kendall test was applied to evaluate the trend of dioxane concentrations at various wells; 3. An automated time series machine learning (AutoTS) package was utilized to predict the best future values forecasts; and 4. An R-based Shiny web application was designed to allow visualization and quantification of dioxane contamination analytical data. This research introduced a novel framework for filling spatial and temporal data sampling gaps in groundwater contamination to offer an effective and promising way to predict future plume concentration and spatial distribution.