Researchers from the University of Hawai‘i (UH) and fishpond stewards in Hilo, Hawai‘i, have recently released a study in the Journal of Remote Sensing demonstrating the use of uncrewed aerial vehicles (UAVs) to support integrated coastal zone management, including at cultural heritage sites, providing a new tool for scientists and kiaʻi loko (fishpond practitioners) to assist in the restoration and resilience of Native Hawaiian fishponds.
“We discovered that drones are effective and cost-efficient tools for mapping loko iʻa at the community level, providing kiaʻi loko iʻa with better insights into the timing and locations of flooding and future sea level rise impacts on their fishponds,” said Kainalu Steward, lead author of the study and Earth sciences doctoral student in the UH Mānoa School of Ocean and Earth Science and Technology (SOEST).
Loko iʻa, traditional Hawaiian fishponds situated along the coastline, have historically served as sustainable seafood sources and are now being revitalized through community-led restoration efforts, as these culturally significant sites are being rejuvenated through community-driven restoration endeavors.
With sea level rise threatening coastal areas, loko iʻa managers are seeking adaptive strategies to address related concerns such as flooding, water quality, and the viability of native fish species, recognizing the significant climate-induced threat posed by sea level rise to these areas.
The researchers’ surveys determined that by 2060, the average sea level along the Keaukaha coastline in Hilo is projected to be comparable to the extreme tidal events, known as King Tides, in summer 2023, according to surveys conducted by the researchers. Steward and Brianna Ninomoto, a master’s student in tropical conservation biology and environmental science at UH Hilo, developed a plan to explore the effects of future sea level rise on loko iʻa by evaluating the impacts of the summer 2023 King Tides.
During the summer, researchers captured drone imagery in real time and monitored water levels using sensors submerged at each loko iʻa, including during extreme high tide events. Comparing flooding predictions derived from drone-obtained topography models and commonly used Light Detection and Ranging (LiDAR)-derived models to the observed flooding captured by drone imagery was part of the study.
The research team discovered that digital elevation models obtained from drone surveys provided accurate estimates of observed flooding during extreme high tide events. In contrast, the LiDAR flood models, which are almost two decades old for the Hilo region, significantly overestimated observed flooding by two to five times.
However, Loko iʻa practitioners mentioned that in severe weather and large swell events, these specific areas modeled from LiDAR data do flood occasionally. This indicates that data collected by LiDAR offers a more cautious and conservative understanding of coastal flooding and highlights the importance of UAV-derived and LiDAR-based data as essential components of coastal management tools.
The research received funding from NASA’s Minority University Research and Education Project (MUREP) to support the project titled “Quantifying Vulnerability to Sea Level Rise Across Multiple Coastal Typologies,” which was led by co-author Haunani Kane, an assistant professor of Earth sciences at SOEST. This program involves underrepresented groups through various initiatives, and it provides multiyear grants to aid faculty and students from Minority Institutions in conducting research aligned with relevant missions.
“One of the goals of this project is to increase the capacity of Native Hawaiian students in assessing and evaluating impacts of sea level rise upon cultural resource sites,” said Kane. “This project supports five undergraduate students and three local Native Hawaiian students as they work towards obtaining their Master’s and Doctorate degrees in science at the University of Hawaiʻi.”
“This research is important for enhancing coastal community adaptation, resilience, and food security in the face of climate change,” said Ninomoto. “This work was ultimately done to support loko iʻa practitioners along Keaukaha and the future management of their ʻāina as the impacts of flooding become more severe.”
The NASA-funded project also includes a focus on storytelling and engaging with the community. John Burns, who is a co-author of the study and an associate professor at UH Hilo specializing in marine science and data science, along with the MEGA Lab, utilizes a community lab space at Mokupāpapa Discovery Center in Downtown Hilo. Here, the research team employs virtual reality and short films to convey narratives and involve the community in conversations about the impact of climate change on coastal resources in Hawaiʻi.
UH researchers have future plans to collaborate with the kiaʻi loko iʻa in Keaukaha to supply current aerial imagery of their fishpond, supporting their efforts in restoration.
“Loko iʻa are examples of how our kūpuna have adapted to changes in climate for generations, and we want to contribute towards their resilience and perpetuation by integrating modern technology,” said Steward.
Journal reference:
- Kainalu K. Steward, Brianna K. Ninomoto, Haunani H. Kane, John H. R. Burns, Luke Mead, Kamala Anthony, Luka Mossman, Trisha Olayon, Cybil K. Glendon-Baclig, and Cherie Kauahi. Highlighting the Use of UAV to Increase the Resilience of Native Hawaiian Coastal Cultural Heritage. Remote Sensing, 2024; DOI: 10.3390/rs16122239