- Planning Department
- Division - Current Planning
- Coastal Zone Management Program
- Maui Shoreline Erosion Atlas
Maui Shoreline Erosion Atlas
OverviewResearchers at the University of Hawaii, under contract from Maui County, have developed maps of coastal erosion hazards along Maui's shoreline. The erosion hazard maps depict the average annual erosion rate calculated by linear regression of historical shoreline positions. These maps are available for locations on the Kihei, West Maui, and North Shore coasts.
Past shoreline positions are measured using georectified nautical and topographic sheets from the pre-WWII era, and all available sets of aerial photographs covering long continuous segments of shoreline. These are usually flown in stereo from the post-WWII era. Pre-WWII N- and T-sheets are made available through the Shoreline Data Rescue Program of the National Oceanographic and Atmospheric Administration Coastal Services Center.
AccuracyIn most cases, aerial photographs have a minimum ground resolution of 0.25 meters (the worst case is 0.47 meters). Photographs have been digitally corrected in three-dimensions (orthorectified) to minimize distortion and maximize position accuracy and precision. Approximately 780 individual aerial photographs are used to calculate erosion rates along 75 kilometers of coast at more than 3,700 locations spaced 20 meters apart.
Calculations are based on six to nine separate shoreline positions between 1899 and 2002. Past shoreline positions that significantly diverge from the historical trend are eliminated from the rate calculation using the least median of squares technique. The 80th percentile uncertainty associated with each erosion rate is available from Maui County Planning Department records.