Researchers from the University of Hawaii have developed a tool to help in the restoration and resilience-building of Native Hawaiian fishponds and fishpond stewards in Hilo, Hawaii, highlighted the use of Unmanned Aerial Vehicles (UAVs) to promote integrated coastal zone management, particularly at cultural heritage sites. The work was published in the Journal of Remote Sensing.
Aerial view of Honokea loko iʻa in Keaukaha, Hilo during low tide. Image Credit: Kainalu Steward.
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.
Kainalu Steward, Study Lead Author, School of Ocean and Earth Science and Technology
Kainalu Steward is a Doctoral Student in the UH Mānoa School of Ocean and Earth Science and Technology.
Sustainable seafood has historically been available from the traditional Hawaiian fishponds called loko iʻa, situated along the coastline. Community-driven restoration projects are revitalizing these culturally significant sites.
However, the management of loko iʻa is looking for adaptive solutions to deal with related issues, including flooding, water quality, and the survival of local fish species, because sea level rise poses a serious threat to coastal areas caused by climate change.
King Tides as Estimate of Future Sea Level
According to the researchers' assessments, the average sea level along Hilo's Keaukaha shoreline by 2060 will resemble the intense tidal events known as King Tides that occurred during the summer of 2023.
Steward and Brianna Ninomoto, a UH Hilo master's student studying tropical conservation biology and environmental science, devised a strategy to evaluate the effects of the summer 2023 King Tides to determine how future sea level rise will influence loko iʻa.
Researchers used submerged sensors at each loko iʻa to measure water levels and captured real-time drone imagery throughout the summer, including during the exceptionally high tide events.
This allowed them to compare the observed floods captured by drone imagery with flooding anticipated from topography models obtained by drones and more widely used models derived from Light Detection and Ranging (LiDAR).
The researchers discovered that whereas LiDAR flood models, which are almost 20 years old for the Hilo region, dramatically overestimated observed flooding by two to five times, digital elevation models built from drone scans accurately projected observed flooding during extreme high tide events.
However, practitioners of loko iʻa have noted that these specific regions modeled using LiDAR data do flood on occasion during severe weather and huge swell events. This indicates that LiDAR data provides a more cautious and conservative interpretation of coastal flooding, highlighting the significance of both LiDAR- and UAV-derived data as essential parts of the array of coastal management tools.
Supporting Native Hawaiian Scientists, Community
This study's co-author and SOEST Assistant Professor of Earth Sciences, Haunani Kane, was given funding via NASA's Minority University Research and Education Project (MUREP) for the project “Quantifying Vulnerability to Sea Level Rise Across Multiple Coastal Typologies.”
The program engages marginalized communities through a wide range of programs. Multiple-year grants are given to academics and students at Minority Institutions to support their research on relevant topics.
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. 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.
Haunani Kane, Assistant Professor and Study Co-Author, School of Earth Sciences, University of Hawaii
Ninomoto said, “This research is important for enhancing coastal community adaptation, resilience, and food security in the face of climate change. 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.”
Another component of the NASA-funded project is storytelling and community outreach. John Burns, study co-author and UH Hilo Associate Professor in Marine Science and Data Science, along with the MEGA Lab, has a community lab space at Mokupāpapa Discovery Center in Downtown Hilo. Here, the research team uses virtual reality and short films to share stories and engage the community in discussions about how climate change impacts coastal resources in Hawaiʻi.
To help restoration efforts, UH researchers intend to keep working with the kiaʻi loko iʻa in Keaukaha to offer current aerial imagery of their fishpond.
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.
Kainalu Steward, Study Lead Author, School of Ocean and Earth Science and Technology
Journal Reference:
Steward, K. K., et al. (2024) Highlighting the Use of UAV to Increase the Resilience of Native Hawaiian Coastal Cultural Heritage. Remote Sensing. doi.org/10.3390/rs16122239.