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Estimating Climate- and Land-Cover Change Impacts on Groundwater Recharge on the Island of Maui
Project Chief: Alan Mair
Fresh drinking water in the Hawaiian Islands is largely derived from groundwater, and changes in climate and land cover can alter rates of groundwater recharge to aquifers. Quantifying the combined influence of climate and land-cover change on recharge is vital for understanding future freshwater availability. Spatially distributed estimates of recharge are also critical input for groundwater flow and transport models used to assess freshwater availability under different demand, climate, and land-cover conditions. At present, very few studies have quantified the effects of climate and land-cover change on recharge in Hawaii.
The objectives of this study are to (1) estimate the spatial distribution of mean groundwater recharge and other water-budget components for a set of climate-land cover conditions, (2) quantify the regional hydrological changes between present-day and future conditions, (3) assess the range of uncertainty in estimated recharge, and (4) assess the effects of climate and land-cover changes on future freshwater availability. The results of this study are being used to support the Pacific RISA study to assess the sustainability of groundwater resources on the island of Maui under future climate conditions.
Relevance and Benefits
Quantifying the hydrologic impacts of climate and land-cover change is critical for understanding future freshwater availability. The results of this study will inform resource managers in Hawaii of the potential impacts of climate and land-cover change on water resources. By quantifying the hydrologic impacts of climate- and land-cover change on groundwater recharge and other water-budget components, this study broadly supports two of the six science directions in the USGS Science Strategy: (1) climate variability and change, and (2) a water census of the United States.
To meet the objectives of this study, the USGS will (1) estimate groundwater recharge using projected future end-of-century climate conditions developed using dynamical and statistical downscaling approaches, and a water-budget model developed for Maui, and (2) estimate groundwater recharge using a set of plausible future land-cover scenarios being developed by the Pacific RISA program. Mean annual recharge will be computed for each climate-land-cover scenario and used to quantify the hydrologic impacts of climate and land-cover change on groundwater recharge.