Waipuilani Mauka is a large area dominated by kiawe and scrub-shrub vegetation. It is an original wetland that has remained undeveloped. Over time, this area has become surrounded by development, and the hydrology has changed. In general, Hawaiʻi is becoming drier while storms are becoming more intense. Climate change, drought, invasive plants, and over-development have placed these scrub-shrub wetlands under increasing stress. However, the aquifer remains strong, and groundwater continues to flow beneath the surface. This wetland is subject to rising and falling water tables and is expected to play an increasingly important role as sea levels rise (SLR). This wetland site floods periodically and continues to play a vital role in the area’s drainage.
Soils
Waipuilani Mauka Wetlands — Ephemeral Wetland Conditions. This photograph documents the site during a period of inundation, providing clear visual evidence of its recurring wetland character and hydrologic function. Although the area may appear dry during extended periods without rain, it is an ephemeral wetland connected to the local groundwater table and network of subsurface springs. Rainfall and changes in groundwater conditions—including rainfall occurring away from the immediate site—can cause water to emerge and collect across the wetland.
Particularly notable in this photograph is the dark, tea-colored to reddish-brown water, together with saturated soils, shallow standing water, wetland vegetation, and the irregular pattern of inundation across the terrain. The coloration is consistent with water interacting with soils and accumulated organic material rather than simply running across the surface as short-lived stormwater runoff. These visible conditions document the site’s hydrologic behavior and provide important visual evidence consistent with its established wetland character and provenance.
Engineering
The gulches above these wetlands have been heavily engineered, and natural watercourses have been diverted around, and in some cases beneath, housing developments. High above Waipuilani Mauka is an unused 50-acre detention basin, and there are plans to fully divert the local watershed into another gulch. This type of engineering has been devastating to the environment and has radically altered the function of the watershed.
The site displays many of the classic indicators of wetland hydrology, including altered vegetation, muddy areas, loose silty soils, extensive salt-crusted surfaces, and other evidence of seasonal pooling. The wetland is most active during periods of rainfall and has the capacity to retain large volumes of stormwater.
Site Vulnerabilities
Waipuilani Mauka lies within the wetland study areas identified by Kolb (1965), Erickson (1991), and STW (2021). It also falls within the Maui County Special Management Area (SMA), Coastal Management Zone (CMZ), and the 3.2-foot Sea Level Rise Coastal Hazard Zone. This wetland and the surrounding landscape are becoming increasingly vulnerable to coastal hazards associated with sea level rise.
Coastal Hazards Due to Sea Level Rise
By approximately 2060, a projected 3.2-foot rise in sea level is expected to place this site within the reach of high wave events, coastal inundation associated with storm surge, and many smaller tsunami events. Preserving the wetland’s natural hydrology will become increasingly important as these coastal hazards intensify.
