The following case study is part of a forthcoming NPS handbook on climate change entitled “Climate Change and Cultural Resources: Impact Assessments and Case Studies.” The original author is Caitlin Smith.
Kaloko-Honokōhau National Historical Park lies along the rugged western coastline of the Big Island of Hawai’i. Although the landscape is uninhabited today, the park commemorates the cultural practices and architectural innovations of ancient Hawaiians who lived in the area for hundreds of years. Because Hawaiian culture is so directly related to the land and geologic process of the island, there is little distinction between natural and cultural resources, revealing a deep reverence toward the landscape still alive in the park today. As such, the effects of climate change, such as sea level rise and intensified storm events, will likewise have significant impacts to the park’s cultural landscape.
Many historic and cultural sites exist within the park, as well as several significant archeological sites. However, the central cultural features of Kaloko-Honokōhau are relics of Hawaiian fishpond architecture including Kaloko Fishpond, Aimakapā Fishpond, Aiōpio Fish trap, and Aiōpio Fish trap Wall. These rock wall fishponds, known as “loko kuapā” in Hawaiian, demonstrate how native Hawaiians managed and harvested marine life from the ocean for hundreds of years (NPS.gov 2011). Nowhere else throughout Polynesia were fishponds so numerous and highly developed as in Hawaii (NPS, Spirit of Kaloko). Built of tightly interlocking volcanic rocks across a natural embayment on the Kona coast, the kuapā are marvels of engineering. They are porous, allowing water to flow in through the wall and circulate around the pond while retaining the fish that passed into the pond with the wave. The angle of the kuapā deflects waves, absorbing the battering energy and shock of the impact (NPS, Spirit of Kaloko).
The kuapā stood intact for 300 years as testament to the ingenuity and skill of the Hawaiian people. The Aimakapā Fishpond was used to raise fish for the ali’i (chiefs) and is thought to be over 600 years old. However, years of exposure to wave action and erosion have slowly caused the kuapā to collapse (NPS, The Spirit of Kaloko).
Park managers are working to rebuild the fishponds at Kaloko-Honokōhau, but sea level rise and increasing storm intensities associated with climate change pose new and significant challenges to their continued preservation (Vitousek et al. 2009).
Scientists project that the Pacific Islands will experience climate changes such as warmer air and sea surface temperatures, more extreme precipitation events associated with stronger El Niño Southern Oscillation (ENSO) atmospheric cycles, and an estimated sea-level rise of 0.1 – 0.88 meters by 2100 (IPCC 2007). Rates of sea-level rise for the Big Island are more severe than the rest of the Hawaiian Islands due to island subsidence. Sea level is rising at a rate of about 3.5 mm/yr at the Big Island and will be approximately 0.15-0.41 meters above present levels by 2050, and 0.32-1.55 meters above present levels by the end of the century (Vitousek et al. 2009).
Coastal overtopping of the park’s kuapā will increase significantly under projected sea-level rise (Vitousek et al. 2009). At present, the Aimakapā Fishpond is the most vulnerable to coastal erosion and sea level rise (Thornberry-Erhlich 2011). The number of large swell events which fully overtop the Kaloko Seawall are expected to increase by a factor of 3-4 by 2050, and by a factor of 10 or more by the end of the century due to stronger ENSO cycles caused by warmer sea surface temperatures (Vitousek et al. 2009; IPCC 2007). This overtopping will continue to significantly undermine the structural integrity of the kuapā.
Healthy fishstocks in the pond are dependent on not only the stability of the fishpond wall, but also on the balance of fresh and salt water in the pond. Submarine groundwater discharge (SDG) flows into the fishponds via groundwater plumes, contributing colder, less saline, and more nutrient rich water to the fishponds. This action effectively creates an estuarine nearshore environment (Vitousek et al. 2009). If seawater begins to continually overtop the kuapā, the water chemistry of the fishpond may become more saline, affecting the marine life and terrestrial habitat within.
Because sea-level rise is a subtle process, flooding will increase gradually at Kaloko-Honokōhau. Nevertheless projected rates of sea-level rise will constantly submerge many of Kaloko-Honokōhau’s kuapā by 2100 (Vitousek et al. 2009). If the kuapā of Kaloko-Honokōhau are not actively maintained into the future, they will likely collapse into the ocean as sea level rises (Vitousek et al. 2009) drowning with them the memory and legacy of traditional Hawaiian culture.
1. The Intergovernmental Panel on Climate Change (IPCC), Fourth Assessment Report, Regional Climate Change Projections, North America, 2007.
2. NPS.gov, Kaloko-Honokohau National Historic Park, history and culture/places, last modified May 3, 2011, http://www.nps.gov/kaho/index.htm.
3. National Park Service, Kaloko-Honokohau National Historic Park, “The Spirit of Kaloko- building in the shadow of the past” p. 1-2.
4. Thornberry-Erhlich, Trista T. “Kaloko-Honokohau National Historical Park Geologic Resources Inventory Report Natural Resource Report” NPS/NRPC/GRD/NRR—2011/384, April 2011, p. 1-66.
5. Vitousek, S., M.M Barbee, C.H. Fletcher, B.M. Richmond, and A.S. Genz, Pu’ukohola Heiau National Historic Site and KalokoHonokohau Historical Park, Big Island of Hawai’i, Coastal Hazard Analysis Report, Natural Resource Technical Report NPS/NRPC/GRD/NRTR-2010/387, May 20, 2009, http://www.soest.hawaii.edu/coasts/nps/nps_report.pdf