Hawai’i Water Resources

Terrestrial NDVI change map of West Maui, Hawai’i, using a Landsat 4/5 TM composite (1989, 1990, 1991) and Landsat 8 OLI composite (2017, 2018), joined with a false-color marine turbidity image from February 10th, 2014, Landsat 8 OLI data.  On land, light shades indicate NDVI decreases while darker shades show NDVI increases. In the water, brown denotes high turbidity. Better understanding the trends in land use and water quality will help partners develop watershed management plans.

Keywords: Landsat 4 and 5 TM, Landsat 8 OLI, NDVI, Turbidity, LULCC, Watershed

Monitoring the Impacts of Land-Based Sources of Pollution on Water Quality Along the Coast of West Maui, Hawai’i to Assess Coral Reef Condition

West Maui is at risk of losing ecosystem services provided by coral reefs due to land-based sources of pollution (LBSP). In 2011, The US Coral Reef Task Force (USCRTF) identified Wahikuli, Honokōwai, Kahana, Honokahua, and Honolua as priority watersheds in West Maui after decades of coral decline, giving rise to the multi-agency West Maui Ridge to Reef (R2R) Initiative. The DEVELOP Hawai’i Water Resources team partnered with the R2R Initiative and the Hawai’i Department of Land and Natural Resources Division of Aquatic Resources (DLNR-DAR) to address the need for better watershed management practices. The team provided the partners with a Google Earth Engine tool that displays land use and land cover changes (LULCC) in the five priority watersheds and detects near-shore turbidity, chlorophyll-a, and sea surface temperature using Landsat 4 Thematic Mapper (TM), Landsat 5 TM, Landsat 7 Enhanced Thematic Mapper (ETM+), Landsat 8 Operational Land Imager (OLI), Terra Moderate Resolution Imaging Spectroradiometer (MODIS), and Aqua MODIS. Team members used ancillary data provided by the R2R Initiative and the USGS Pacific Coastal and Marine Science Center (PCMSC) to validate satellite parameter values. The land cover analysis captured a general trend of increasing impervious cover and decreasing vegetated cover from 1989 to 2019; however, the extent of this change varied between each watershed. This analysis, coupled with the tool, can help project partners continually monitor terrestrial and marine patterns associated with coral decline.

California — Ames
Fall 2019
US Coral Reef Task Force, West Maui Ridge to Reef Initiative
Hawai’i Department of Land and Natural Resources, Division of Aquatic Resources
USGS Pacific Coastal and Marine Science Center
NASA Earth Observations
Landsat 4 TM
Landsat 5 TM
Landsat 7 ETM+
Landsat 8 OLI
Arev Markarian (Project Lead)
Emily Deardorff
Arthur Platel
Sophia Skoglund
Dr. Juan Torres-Pérez (Bay Area Environmental Research Institute, NASA Ames Research Center)