Vulnerability assessment of hawai'i's cultural assets attributable to erosion using shoreline trend analysis techniques

Hawai'i's beaches are a focal point of modern lifestyle as well as cultural tradition. Yet coastal erosion threatens areas that have served as burial grounds, home sites, and other forms of cultural significance. To improve understanding of the convergence of erosion patterns and cultural uses, we mapped shoreline changes from Kawela Bay to Kahuku Point on the capital island of O'ahu. Shoreline change rates are calculated from historical photographs using the single-transect (ST) and eigenbeaches (EX) method to define the 50-and 100-year erosion hazard zones. To ensure that shoreline change rates reflect long-term trends, we include uncertainties attributable to natural shoreline fluctuations and mapping errors. A hazard zone overlay was compared to cultural data provided by the Hawaii State Historic Preservation Division (SHPD) and the Office of Hawaiian Affairs (OHA) to identify threats to cultural features. Cultural features identified in the study include iwi kupuna (burials), Hawaiian artifacts, and Punaulua (a freshwater spring). Our analysis indicates that, except for Punaulua, all cultural features identified are vulnerable to coastal erosion at historical rates. The data produced in this study may be used as a proactive management tool to rank the vulnerability to threatened cultural features, as well as to develop protocols to appropriately manage cultural assets.