Cloud water interception in Hawai‘i – Part 1: Understanding the impact of fog on groundwater and ecosystems and future changes to these processes

View across high-elevation slopes with clouds intruding between foreground bushes and background volcanic crests.
Fog brushes the high elevation Haleakala forests, contribution cloudwater to the hydrologic system. (Photo:TGiambelluca)

On Hawai‘i’s mountains, cloud droplets, propelled by strong winds, are deposited on plants, where they accumulate and drip to the ground, adding water over and above that supplied by rainfall. Prior studies show that the amount of intercepted cloud water is substantial, and variable from place to place. Estimates of the spatial patterns of cloud water interception (CWI), the fog-related effects on plants, and the contributions of fog to groundwater recharge and surface water flows are needed to better understand the water cycle and predict effects of climate change on water supply and ecosystems. We will make measurements of fog, wind, fog interception, soil moisture, and fog effects on plant water use and plant survival. We will test a model to estimate CWI as a function of fog-water movement and vegetation characteristics. This study will also support two companion projects. In the first, our results will be combined with a regional climate model to map the present and future patterns of CWI statewide. In the second project, our results will help determine the importance of groundwater recharge derived from CWI, and to help map the present and future patterns of soil moisture and recharge throughout the Hawaiian Islands.





Thomas Giambelluca
Professor of Geography, UH Mānoa