Development of Statistical Methods to Estimate Baseline and Future Low Flow Characteristics of Ungaged Streams in Hawai`i
Climate change will affect the beneficial uses of streamflow, which include supplying freshwater for irrigation and domestic needs, providing for traditional and customary Hawaiian practices, and maintaining habitat for native stream fauna.
Statistical models were developed to estimate surface-water availability during low-flow conditions for varying rainfall conditions. Results of this study include a spatial understanding of changes in low flows and usable stream habitat on Maui for a range of projected rainfall conditions for the late 21st century. This analysis indicates that stream responses to rainfall vary spatially in Hawai‘i. For example, a 10-percent decrease in rainfall may result in a 7% decrease in low flows in West Maui streams, compared to a 20-percent decrease in low flows in East Maui streams. The simple models developed for this study are appropriate for regional climate-change impact assessments given the available data and uncertainty in climate projections. The methods developed for this study are transferable to other Pacific islands as well as continental settings.