Investigating groundwater flow and quality in lahaina beaches affected by the 2023 Maui wildfire

Abstract

On August 8, 2023, a devastating wildfire burned through Lāhainā, Maui. This major wildfire’s destruction introduced the risk of groundwater contamination from structure fires and boat storage damage in the nearby vicinity, leading to the potential for large amounts of chemicals (i.e. solvents, paint and oils) to seep into the ground. These contaminants may be detrimental to the long-term health of Lāhainā’s environment and community, and this study addresses their potential transport pathways with groundwater flow. In this study we developed a high-resolution, physics-based groundwater model to quantify coastal groundwater dynamics (flow, salinity, and water levels) in a Lāhainā beach affected by the wildfire, and to investigate the pathways and persistence of contaminants in Lāhainā beach environments. The model is further calibrated and validated based on field measurements of water levels and salinity. The study site is focused on a southern Lāhainā beach, where two transects were installed on the beach, perpendicular to the shoreline, one consisting of four piezometer wells, and the other of six multiport wells. The measurements from these wells, along with the analysis of seawater samples, are used as inputs for the groundwater model. The combined field measurements and groundwater modeling provide an understanding of potential pathways and the persistence of contaminants from the wildfires in Lāhainā’s coastal beach environments. These findings can provide insights into assessing the vulnerability and resilience of coastal aquifer systems to wildfire induced contamination, better preparing the development of effective mitigation strategies for affected communities.