Estimated Groundwater Recharge for Mid-Century and End-of-Century Climate Projections, Kaua‘i, O‘ahu, Moloka‘i, Lāna‘i, Maui, and the Island of Hawai‘i
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- Document: Report (33 MB pdf)
- Related Work: Scientific Investigations Report 2023-5141 - Effects of Drought and Cloud-Water Interception on Groundwater Recharge and Wildfire Risk for Recent and Future Climate Conditions, Islands of Kauaʻi, Oʻahu, Molokaʻi, Maui, and Hawaiʻi
- Data Release: USGS Data Release - Mean annual water-budget components for Kaua‘i, O‘ahu, Moloka‘i, Lāna‘i, Maui, and the Island of Hawai‘i, for a set of recent and future-climate conditions, and 2020 land cover
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Abstract
Demand for freshwater in the State of Hawaiʻi is expected to increase by roughly 13 percent from 2020 to 2035. Groundwater availability in Hawaiʻi is affected by a number of factors, including land cover, rainfall, runoff, evapotranspiration, and climate change. To evaluate the availability of fresh groundwater under projected future-climate conditions, estimates of groundwater recharge are needed. A water-budget model with a daily computation interval was used to estimate the spatial distribution of groundwater recharge for Kauaʻi, Oʻahu, Molokaʻi, Lānaʻi, Maui, and the Island of Hawaiʻi for recent climate conditions and three future-climate scenarios. Climate conditions from 1978 to 2007 were used as the reference period for recent climate conditions on each island. The three future-climate scenarios were developed using available high-resolution downscaled climate projections that include (1) a mid-century scenario using projected rainfall conditions for the Representative Concentration Pathway (RCP) scenario during 2041–71 with a total radiative forcing of 8.5 watts per square meter by the year 2100 (RCP8.5 2041–71 scenario), (2) a dry-climate scenario using projected rainfall conditions for the RCP8.5 scenario during 2071–99, and (3) a wet-climate scenario using projected rainfall conditions for the “Special Report on Emissions Scenarios” A1B scenario during 2080–99 for Maui, the RCP4.5 scenario during 2080–99 for Kauaʻi, Lānaʻi, and the Island of Hawaiʻi, and the RCP8.5 scenario during 2080–99 for Oʻahu and Molokaʻi. An additional drought scenario was added for Lānaʻi to assess the effect of extreme drought conditions during 2008–12 on groundwater recharge. All scenarios used 2020 land cover.
Mean annual groundwater recharge is estimated to decrease between 5 and 55 percent on all six islands in this study for the mid-century and dry-climate scenarios relative to the reference-period recharge. Recharge is estimated to increase for Kauaʻi, Oʻahu, Molokaʻi, Lānaʻi, and Maui between 2 and 43 percent and decrease for the Island of Hawaiʻi by about 4 percent for the wet-climate scenario. Comparing the mid-century and dry-climate scenarios, all 110 aquifer systems (management areas defined by the State of Hawaiʻi Commission on Water Resource Management) from all six islands show similar direction in drying (104 aquifer systems) or wetting (6 aquifer systems) changes for recharge. However, among the three future scenarios, only 35 of 110 aquifer systems show similar direction in drying (30 aquifer systems) or wetting (5 aquifer systems) changes for recharge.
Suggested Citation
Kāne, H.L., Mair, A., Johnson, A.G., Rotzoll, K., Mifflin, J., and Oki, D.S., 2024, Estimated groundwater recharge for mid-century and end-of-century climate projections, Kaua‘i, O‘ahu, Moloka‘i, Lāna‘i, Maui, and the Island of Hawai‘i: U.S. Geological Survey Scientific Investigations Report 2023–5130, 133 p., https://doi.org/10.3133/sir20235130.
ISSN: 2328-0328 (online)
Study Area
Table of Contents
- Acknowledgments
- Abstract
- Introduction
- Study Area
- Climate Scenarios
- Water-Budget Model
- Water-Budget and Groundwater-Recharge Estimates
- Implications of Estimated Changes in Groundwater Recharge
- Effects of Selected Climate Inputs on Estimated Recharge
- Study Limitations
- Summary
- References Cited
- Appendix 1. Estimation of Model Input Parameters for Kiawe
- Appendix 2. Summary of Mean Annual Water-Budget Components
- Appendix 3. Development of Daily Rainfall Fragment Sets, Forest-Canopy Evaporation Parameters, and Reference-Evapotranspiration Rates for HRCM1 and HRCM2 Scenarios
| Publication type | Report |
|---|---|
| Publication Subtype | USGS Numbered Series |
| Title | Estimated groundwater recharge for mid-century and end-of-century climate projections, Kaua‘i, O‘ahu, Moloka‘i, Lāna‘i, Maui, and the Island of Hawai‘i |
| Series title | Scientific Investigations Report |
| Series number | 2023-5130 |
| DOI | 10.3133/sir20235130 |
| Year Published | 2024 |
| Language | English |
| Publisher | U.S. Geological Survey |
| Publisher location | Reston, VA |
| Contributing office(s) | Pacific Islands Water Science Center |
| Description | Report: viii, 133 p.; Data Release |
| Country | United States |
| State | Hawaii |
| Online Only (Y/N) | Y |
| Google Analytic Metrics | Metrics page |