I Paʻa Hou i Kalou: Visualizing the Restoration Suitability of Loko Wai and Loʻi Kalo at Waialeʻe, Oʻahu

Nick Kawelakai Farrant. M.S. Candidate, Natural Resources and Environmental Management, University of Hawaiʻi at Mānoa.

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Introduction

Coastal wetlands are ecologically and culturally important, though commonly threatened by human activity (Bruland, 2008). Understanding the historic context and current condition of a wetland is beneficial to assessing the restoration suitability of the site. Here, I assess the suitability of restoring the historic wetland agro-ecosystem of Kalou, a present-day marsh in Waialeʻe, Oʻahu. To do so, I set out to answer the following questions:

  1. What was the 19th Century extent of wetland agriculture at Kalou?
  2. What is the current extent of the wetland at Kalou?
  3. To what extent could wetland agriculture be restored at Kalou?
Figure 1. An aerial view of Kalou Fishpond and marsh (former loʻi kalo) from March 2019 (McDonald, 2019a).

 

 

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Background

Three types of wetland agricultural systems are historically documented at Kalou (Kikuchi, 1973):

  1. Loko Wai - freshwater fishpond
  2. Loʻi Kalo - wetland taro cultivation
  3. Loko Iʻa Kalo - hybrid loʻi kalo + loko wai
Figure 2. Schematics of a loko wai (left) and loko iʻa kalo and/or loʻi kalo (right) (Kikuchi, 1973).
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Methods

Archival Data Extraction

Figure 3. A 1902 map of Waialeʻe showing native land claims awarded via the Kuleana Act of 1850. I extracted land use information from the original documents corresponding to each individual land claim in Waialeʻe (Emerson, Lowell, and Wall, 1902).

UAV Survey

Figure 4. In order to determine the current extent of Kalou accurately and efficiently, I enlisted a colleague to conduct an unmanned aerial vehicle (UAV) survey of Kalou. This is the resulting ortho-rectified composite image (McDonald, 2019b).

Field Surveys

Figure 5. Field techniques including water sampling and qualitative observation were used to augment archival and geospatial methods. Here, Buddy Keala (left), a Hawaiian fishpond specialist, tests water quality at Kalou marsh. Richard Fisher (right), a University of Hawaiʻi employee and lifelong Waialeʻe resident, has also provided invaluable insight to the historic conditions of Kalou.

Suitability Analysis

To determine the historic wetland extent of Kalou, I used ArcMap to geo-reference Emerson, Lowell and Wall, 1902, and hand-digitize the historic wetland extent deliniated on the map (Figure 6). Similarly, to determine the current state of Kalou, I hand-digitized the present wetland extent and general land-cover types from McDonald, 2019b (Figure 7). Finally, I combined the two aforementioned maps to assess the suitability of restoring the traditional wetland agro-ecosystem of Kalou (Figure 8).

 

 

 

 

 

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Results
Figure 6. Extent of historic taro lands and current wetlands at Waialeʻe.

 

Figure 7. An illustration of general land cover types at Waialeʻe based on Mcdonald, 2019b.

 

Figure 8. Suitability for restoration of wetland agriculture at Waialeʻe.
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Discussion and Conclusion

Assumptions

For the purposes of this study, I assumed that:

  1. historically-documented agricultural production is a proxy for historic agricultural suitability.
  2. current structures and/or incompatible land uses are the only major factors precluding restoration.
  3. other factors, such as pollution, if present, would affect the wetland homogeneously.
  4. all vegetative land cover types can be restored, though they vary in required effort.

Limitations

This study bears a few other notable limitations.

  1. Map features were digitized by hand.
  2. Relatively few suitability criteria were considered.
  3. Criteria weights were not empirically determined.

Conclusion

This study demonstrates high potential for agro-ecological restoration of Kalou. It shows how diverse methods can be used to:

  1. visualize historic geography and assess current state of Hawaiian agro-ecosystems.
  2. determine restoration potential of these sites.

In addition to addressing limitations, future work could incorporate:

  1. projected changes to temperature, rainfall, solar radiation, and sea level.
  2. more Hawaiian archival resources including newspapers, land records, and maps.
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Works Cited

Bruland, G. L. (2008). Coastal wetlands: function and role in reducing impact of land-based management. In A. Fares & A. I. El-Kadi (Eds.), WIT Transactions on State of the Art in Science and Engineering (1st ed., Vol. 1, pp. 85–124). https://doi.org/10.2495/978-1-84564-091-0/04

Emerson, J. S., Lowell, F. L., & Wall, W. E. (1902). Lower Portion of Waialee, Koolauloa, Oahu. In Hawaii Territory Survey. Retrieved from http://www.avakonohiki.org/uploads/1/2/5/5/12550111/waialee_hgs2109_1902.pdf

Kikuchi, W. K. (1973). Hawaiian aquacultural system (University of Arizona). Retrieved from http://hdl.handle.net/10150/565277

McDonald, Kristian (2019a). Aerial View of Kalou Fishpond and Marsh, Waialeʻe, Oʻahu.

McDonald, Kristian (2019b). Ortho-Rectified Mosaic of Kalou Fishpond and Marsh, Waialeʻe, Oʻahu.

 

Figures and claims not otherwise cited were produced by the author.

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This work would not have been possible without funding from the Hauʻoli Mau Loa Foundation, guidance from my advisors Dr. Carl Evensen and Dr. Mehana Vaughan, and other assistance by Kristian McDonald, Ikaika Lowe, Richard Fisher, Buddy Keala, and Thomas Lim. Mahalo nui.