WUI
fire Wildland-Urban Interface — the zone where development meets undeveloped wildland, creating high fire risk.
Lahaina’s peri-urban edge exemplifies the wildland-urban interface condition that produced the 2023 catastrophe. After Pioneer Mill’s closure in 1999, the agricultural land the plantation had maintained reverted to dry grass, accumulating the fuel that would feed future fires. The 100-foot defensible space clearance required in the framework derives from Firewise USA best practice for wildland-urban interface zones. Given Lahaina’s fuel load conditions — primarily invasive guinea grass (Megathyrsus maximus) with fire spread rates exceeding 6 mph under Kona wind conditions — the 100-foot minimum represents baseline, not maximum, clearance.
The peri-urban buffer in the proposed framework directly addresses WUI vulnerability, functioning as an irrigated agricultural firebreak between the developed town and the dry grasslands of the hinterland. Fire-resistant planting prioritizes species that maintain green cover and high fuel moisture during dry seasons, interrupting the fuel continuity that enabled the 2023 fire spread.