Water Resource Sustainability

09 Mar: Assessing the vulnerability of coastal wastewater infrastructure to climate change

PI: Daniele Spirandelli
This research aimed, with community and agency stakeholders, to identify and map critical factors contributing to wastewater infrastructure vulnerability to a changing climate, particularly sea-level rise and extreme precipitation, and to develop a process that builds adaptive capacity into the system. Results showed groundwater inundation as a significant threat to sewer pipes, and a policy gap analysis identified discontinuities in key components of Hawaiʻi’s current onsite management program between land-use planning efforts and state siting regulations.

09 Mar: Predicting Hawaiʻi water demand under climate change

PI: Michael Roberts
This project studied how climate change may affect future water demand on Oʻahu, focusing on variations in temperature, precipitation, and prevailing climatic conditions. Results imply that microclimates play an important role in demand, with the hot and dry area households using typically 100 gallons more per day than those in cooler, wetter aras. Using water billing data cross-referenced with fine-scale weather data, a model was developed that estimates the growth of Oʻahu aquifer yields needed to satisfy possible shifts in demand (up to 50% increase) under different climate scenarios, or alternatively, the price increases necessary to limit consumption levels.

08 Mar: Collaborative investigation of hydraulic and geochemical connectivity between wastewater and land-use and the oceanic waters of Kāneʻohe Bay, Oʻahu

PI: Craig Glenn
This project examined the environmental and health risks of wastewater leakage from on-site sewage disposal systems, by assessing the hydraulic and geochemical connectivity between wastewaters and ocean waters of Kāneʻohe Bay using field studies and pioneering thermal infrared imaging mounted on unmanned aerial vehicles (UAVs). The remote sensing enabled the team to produce high-resolution maps of groundwater and wastewater leakage from local septic systems into waters of the Kahaluʻu watershed and Kānaʻohe Bay. A local-scale model was developed from sixteen months of data that will help inform remediation strategies to address wastewater leakage problems in the area.

08 Mar: The role of surface and groundwater inputs in driving water quality in Kāneʻohe Bay, Oʻahu

PI: Henrietta Dulai
The goal of this project was to identify submarine groundwater discharge locations and quantify groundwater and its derived nutrient flow into Kāneʻohe Bay, particularly as it varies with wet and dry seasonal cycles. The researchers found that most freshwater in nearby coral reefs derives from streams during the wet season, but during the dry season, input from groundwater increases 150%. These results have led to maps with quantification of groundwater discharge, and measurements of nutrient fluxes have identified several watershed hotspots of wastewater contamination.