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Statistical Methods to Estimate Climate-Change Impacts on Low-Flow Discharges of Hawaii Streams
Project Chief: Maoya Bassiouni
Freshwater resources in oceanic islands are extremely vulnerable to climate change, particularly changes in precipitation, because islands have limited size and storage capacity. Low-flow discharges in Hawaii streams provide a variety of beneficial uses that include maintaining fish and wildlife habitat, supplying freshwater for irrigation and domestic uses, and protecting traditional and customary Hawaiian rights. However, the impacts of projected climate changes in Hawaii streams, particularly low-flow discharges, remain unquantified.
The objectives of this study are to (1) estimate low-flow discharges of ungaged streams in Hawaii for current and future climate conditions, and (2) quantify changes in physical habitat for native stream fauna associated with projected changes in low-flow discharges.
Relevance and Benefits
The results from this study are necessary for the proper management of the surface waters in the State. The study is consistent with the USGS Science Strategy to provide citizens, communities, natural-resource managers, and policymakers with a clearer knowledge of the status of their water resources. By providing estimates of low-flow characteristics and analyzing the effects of climate change on low-flow discharges that provide public-water supply and support fragile ecosystems, this study broadly supports three of the six USGS science directions: (1) a water census of the United States; (2) understanding ecosystems and predicting ecosystem change; and (3) climate variability and change.
To meet the objectives of this study, the USGS will (1) analyze low-flow duration discharges at continuously gaged sites, and relate the spatial and temporal variability in these records to basin physical characteristics and climate conditions; (2) develop statistical methods to estimate low-flow duration discharges at ungaged sites for current climate conditions; (3) evaluate the applicability of the statistical methods to estimate low-flow duration discharges for future climate conditions; and (4) modify relations between streamflow and habitat for selected native fauna to estimate the physical-habitat change associated with climate change. Results from this study will be published in a peer-reviewed journal article.