As sea level rises, much of Honolulu and Waikiki vulnerable to groundwater inundation

>> Narrator: A large part of urban Honolulu, including the tourist hub of Waikiki, is at risk from sea level rise through a combination of groundwater inundation and storm drain flooding, according to new research by the University of Hawaii at Manoa. Groundwater inundation is when groundwater is lifted above the land surface as the sea level rises. Storm drain flooding occurs when high tide enters storm drainage and flows onto streets, which already happens in areas near Honolulu International Airport. >> Chip Fletcher, Associate Dean, School of Ocean and Earth Science and Technology: Ultimately, what will happen is when the water table breaks out on the ground’s surface, you create, what we all know, is a wetland. And a wetland in an urban, vital corridor, is not a good thing.

>> Narrator: Sea level is projected to rise three feet this century if greenhouse gas emissions are not significantly reduced. >> Shellie Habel, UH Manoa geology and geophysics graduate student: With about three feet of rise, about a quarter of the study area will be flooded, so that study area includes Waikiki, Kakaako and Moiliili. There will likely be about $5 billion of taxable real estate that’s affected by this. >> Narrator: Researchers from the UH Manoa Department of Geology and Geophysics in the School of Ocean and Earth Science and Technology developed a computer model that accounts for geology, hydrology, ground surface elevations and other factors to simulate future flood scenarios. >> Habel: Underground infrastructure such as basements and cesspools, buried electrical, that will also be vulnerable to flooding, even before that water level reaches the ground surface.

>> Fletcher: The results are going straight to our city and state agencies, and we are working with them in terms of making sure that there is no interruption to commercial activity or tourism activity. >> Narrator: The computer model and methodology, developed at UH Manoa, has the potential to assist vulnerable coastal communities around the world..