Predicting sea level rise impacts to coastal wastewater infrastructures and water quality along the Kailua-Kona shoreline

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dc.contributor.advisorWiegner, Tracy
dc.contributor.authorKamau, Ihilani kawaipunahele ʻo omokaʻa
dc.contributor.departmentTropical Conservation Biology & Environmental Science
dc.date.accessioned2025-01-23T21:15:27Z
dc.date.available2025-01-23T21:15:27Z
dc.date.issued2024-12
dc.description.degreeM.S.
dc.identifier.urihttps://hdl.handle.net/10790/43924
dc.subjectClimate change
dc.subjectConservation biology
dc.subjectWater resources management
dc.subjectDye tracer test
dc.subjectFecal indicator bacteria
dc.subjectMacroalgae
dc.subjectNutrients
dc.subjectPollution score
dc.subjectStable nitrogen isotopes
dc.titlePredicting sea level rise impacts to coastal wastewater infrastructures and water quality along the Kailua-Kona shoreline
dc.typeThesis
dcterms.abstractSea level rise (SLR) poses a serious threat to coastal infrastructures. On-site sewage disposal systems (OSDS) and wastewater infrastructure (WI) are vulnerable, and when inundated, will result in human and ecosystem health threats. This study focused on the Kailua-Kona shoreline, Hawai‘i Island, where these two sewage sources are potentially impacting water quality. Study goals were to: 1) document and identify sewage pollution hotspots by assessing current water quality conditions, 2) map out and assess predicted SLR to determine what OSDS and WI are at risk of inundation. Sewage pollution hotspots were assessed using a dye tracer test and monthly water quality sampling at 12 stations from August 2022 to September 2023. At Kahaluʻu, dye traveled at 278 m/d, reaching the shoreline in < 6 hours. While Enterococcus spp. concentrations occasionally exceed water quality standards, Clostridium perfringens did not. Staphylococcus aureus was also detected, but Methicillin-resistant S. aureus was not. Nutrient concentrations were variable. Macroalgal δ15N measurements, a stable isotope mixing model, and a sewage pollution score determined that groundwater is the dominant source of NO3- at our stations contributing 77%. However, the results did display a sewage influence on these stations. We examined six different SLR scenarios (2024 Mean higher high water (MHHW), 0.3, 0.6, 1, 1.5, 2 m) and at 0.3 m SLR, 58 OSDS will be at risk of inundation and at a 2 m SLR, this number doubles. We also found that the majority of WI is already being inundated during MHHW events (66 manholes, 79 mains). Our results show that Kailua-Kona is already impacted by sewage pollution and that this will continue to worsen with SLR if management actions are not taken. The entire shoreline from Kailua-Kona to Keauhou should be a Priority 1 area for cesspool conversion for Hawai‘i County, and sewer line setbacks are needed; our results can help guide this effort. Our findings illustrate that adaptive planning is needed to protect future water quality and increase coastal resilience in Hawai‘i, as well as elsewhere where coastal waters are impacted by OSDS and WI.
dcterms.extent47 pages
dcterms.languageen
dcterms.publisherUniversity of Hawaii at Hilo
dcterms.rightsAll UHH dissertations and theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner.
dcterms.typeText
local.identifier.alturihttp://dissertations.umi.com/hilo.hawaii:10263

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