RAPID: Post-Wildfire Runoff from Burned Urban Coastal Landscape

Wildfire is a disaster in multiple facets. On Aug 8, 2023, the unexpected wildfire in Lahaina West Maui was unprecedented for Hawai‘i. The fire that burned across unmanaged grasslands and urban landscapes adds complexity and uncertainty to the impact of post-fire runoff.

The resulting ash and contaminants are detrimental to residents and livelihood in Lahaina. The environment is covered in ash, excessive sediment, and contaminants. Runoff from the land will drain into deltaic and coastal geomorphology, affecting marine and riverine geochemistry and coastal ecosystems.

The non-linear and complex attributes of this unique former agricultural and urban landscape make it challenging to predict without immediate sampling, documenting and continued studying of the evolvement of the burned watershed. This is particularly true when storms are anticipated as Hawai‘i is entering its rainy season (starting from October), for which no prior observational data exists.

The foreseeable storms will cause undesirable ash wash-off from burned areas and sediment erosion to the near-shore and damage the biodiversity and fisheries. For this RAPID project, the PI seeks to survey and install instruments to collect storm runoff and sediment samples after the wildfires in Lahaina. By promptly documenting and disseminating perishable and time-sensitive post-fire data, this research empowers affected residents with the knowledge to make informed decisions regarding their immediate safety and long-term environmental well-being.

This RAPID project proposes to address the pressing need to sample the data of post-wildfire impact in Lahaina West Maui, Hawai‘i. The devastating wildfire on August 8, 2023, was an unexpected and unprecedented disaster to this historical coastal city and presents an opportunity to investigate post-fire runoff dynamics, sedimentation, and contaminant transport in a volcanic, steep, and urban landscape.

This project employs field and laboratory methods to collect data on water quality, sediment fluxes, and soil and ash samples. Discrete water samples and turbidity measurements will be collected along the Kahoma Stream and terrestrial soil and ash samples will be collected across the broader Lahaina region. Autosamplers will be installed within Kahoma Stream to facilitate long-term tracking.

Using autosamplers allows for the collection of continuous samples over multiple storm events to represent fluvial sediment fluxes from the burned landscape. The data, disseminated through community engagement, established scientific channels, and a web-GIS portal, will enhance our knowledge of wildfire impacts on coastal ecosystems, coral reefs, biodiversity, and fisheries.

This study contributes to the emerging environmental science on disaster resilience. By focusing on a rare, urban wildfire with proximity to a coastal area, this project offers a unique lens through which to understand the intricate interplay between wildfires, hydrological systems, and ecological responses. This research advances our fundamental knowledge of post-fire dynamics and facilitates the development of predictive models and mitigation strategies for similar coastal regions facing increasing wildfire risks due to climate change.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.