Scientists and kia’i loko (fishpond managers) now have a new tool to aid in their efforts to ensure the resilience of Native Hawaiian fishponds. Researchers from the University of Hawaii (UH) and fishpond managers in Hilo, Hawaii, recently Journal of Remote Sensing Emphasize the use of unmanned aerial vehicles (UAVs) to support integrated management of coastal zones, including cultural heritage.
“We found that drones are an effective, cost-effective tool for mapping loko’ia at the community level, providing great insights for K’ai loko’ia into the timing and location of flooding and how future sea-level rise will affect their fishponds,” said Kainalu Steward, lead author of the study and a geosciences doctoral student in the University of Hawai’i at Manoa’s School of Ocean and Earth Sciences and Technology (SOEST).
Lokoia, traditional Hawaiian fishponds along the coast, have historically provided a sustainable source of seafood. These culturally significant sites are being revitalized through community-led restoration efforts. However, as sea-level rise poses a significant climate-induced threat to coastal communities, lokoia managers are exploring adaptation strategies to address associated concerns such as flooding, water quality, and the viability of native fish species.
King tides predict future sea level rise
The researchers found that by 2060, average sea levels along Hilo’s Keaukaha coastline will be similar to an extreme tidal event known as a king tide in the summer of 2023. Steward and Brianna Ninomoto, a master’s student in tropical conservation biology and environmental science at the University of Hawaii at Hilo, devised a plan to investigate how future sea-level rise will affect Lokoia by assessing the impacts of the summer 2023 king tide.
The researchers collected drone imagery in real time throughout the summer, including during extreme high tides, and monitored water levels using sensors installed at each locomotive. This allowed them to compare predicted flooding from drone-based terrain models and more commonly used Light Detection and Ranging (LiDAR)-based models with observed flooding recorded by the drone imagery.
The research team found that while digital elevation models derived from drone surveys accurately estimated observed flooding during extreme storm surges, a nearly 20-year-old LiDAR flood model covering the Hilo area overestimated observed flooding by 2-5 times. However, Locoia experts reported that during severe weather or large swells, these specific areas modeled from LiDAR data occasionally flood. This suggests that data collected by LiDAR can provide a more conservative and cautious understanding of coastal flooding, highlighting the importance of UAV-derived and LiDAR-based data as an important component of the coastal management toolkit.
Supporting Native Hawaiian scientists and communities
Funding for this research was provided through NASA’s Minority Undergraduate Research and Education Project (MUREP) for the “Quantifying Vulnerability to Sea-Level Rise Across Multiple Coastal Typologies” project, led by co-author Haunani Kane, assistant professor of geosciences at SOEST. The program engages underrepresented populations through a variety of initiatives: multi-year grants are awarded to support research on relevant missions for faculty and students at minority-represented institutions.
“One of the goals of this project is to increase Native Hawaiian students’ ability to evaluate and determine the impacts of sea level rise on their cultural resources,” Cain said. “The project will support five undergraduate students and three local Native Hawaiian students pursuing Master of Science and PhD degrees at the University of Hawaii.”
“This research is important for strengthening coastal communities’ adaptability, resilience and food security in the face of climate change,” Ninomoto said. “Ultimately, this study was conducted to support the future management of loko’ia practitioners and their aina along Keaukaha as flood impacts become more severe.”
Storytelling and community outreach are another element of the NASA-funded project: Study co-author John Burns, an associate professor of marine and data science at the University of Hawaii at Hilo, and the MEGA Lab have set up a community lab space at the Mokupapa Discovery Center in Downtown Hilo, where the research team uses virtual reality and short films to share stories and engage in discussions with the community about how climate change is affecting Hawaii’s coastal resources.
UH researchers will continue to work with Keaukaha’s Kiai Loko Ia to provide updated aerial photography of the fishponds to assist with restoration efforts.
“Loko Ia is an example of how our kupuna have adapted to climate change for generations, and we hope to contribute to their resilience and permanence by integrating modern technologies,” Steward said.
