A review of multistage modeling of DNAPL behavior in groundwater: From process simulation to integrated modeling approach

Groundwater contamination by dense non-aqueous phase liquids (DNAPLs) poses a significant global environmental challenge due to their persistence, toxicity, and complex migration behavior in subsurface environments. Mathematical modeling is essential for understanding DNAPL behavior, including phase migration, mass dissolution, solute transport, and back diffusion from low-permeability zones. Covering studies published between 1991 and 2024, this paper systematically reviewed processes and modeling approaches for DNAPL migration and fate, while evaluating their use in identifying contamination sources and developing remediation strategies. Furthermore, this paper proposed a comprehensive open-source modeling framework that integrates multiphase flow and solute transport simulations to model the entire lifecycle of DNAPL contamination, aiming to improve remediation strategies by providing a holistic understanding of DNAPL behavior in heterogeneous aquifers. Finally, future research directions were outlined, including advancements in multiscale modeling, the incorporation of high-resolution field data, and the utilization of machine learning to enhance predictive accuracy and decision-making processes in the management of DNAPL-contaminated sites.