Identifying the Risk of Runoff and Erosion in Hawaiʻi’s National Parks

Haleakalā National Park (HNP) and the surrounding landscape spans many different land cover types, some of which are undergoing vegetation changes that can reduce the amount of water that  infiltrates into soil. Decreased soil infiltration can lead to the erosion of terrestrial habitats, increases in the amount of sediment entering aquatic habitats, and flooding of downstream areas as runoff increases after storms. Currently, HNP managers are attempting to control runoff and erosion to avoid loss and damage within park boundaries and parks located downstream. Managers in HNP have expressed a need for information on current and future runoff and erosion risk to help prioritize management within the park and other DOI-managed lands across Hawaiʻi.



This project will build upon previous work in which researchers completed the largest field effort to characterize soil infiltration rates across forests in Hawaiʻi. In collaboration with the National Park Service, the U.S. Geological Survey, and the Pacific Regional Integrated Science and Assessments (RISA), researchers will leverage existing forest-related soil infiltration data to develop maps illustrating the probability of runoff across the Hawaiian landscape, with particular emphasis on HNP, under current and potential future climate conditions. To accomplish this goal, researchers will compare soil infiltration data to rainfall intensity data to calculate current  runoff risk. They will then examine projected changes in the frequency and intensity of rainfall for the state, to determine how runoff might change, and will use this information to develop scenarios of potential future runoff. Throughout the process, researchers will hold discussions with  HNP managers and their partners about what information from these predictions will be most useful to them, subsequently providing opportunities for managers to incorporate runoff scenarios into their climate adaptation planning processes.