Big Island to plot flood hazards
The study comes after heavy rainfall during the last two summers
Associated Press
KAILUA-KONA » Hawaii County officials are planning a major project to identify new floodways in response to heavy summer storms the last two years.
The study could cost about $10 million and will map out floodways for the entire island, with an initial focus on the districts of South Kona and Puna, Deputy Director of Public Works Jiro Sumada said.
The county hopes to begin mapping and assessing hard-hit areas in those two districts by next summer, he said.
Localized areas in both districts typically bear the brunt of heavy downpours on the Big Island.
In August, flash floods ran through three neighborhoods in Captain Cook and rainwater rushed across Mamalahoa Highway. More than 4 inches of rainfall damaged homes, businesses and crops, and Konawaena Middle School delayed opening for two days.
A storm almost exactly one year earlier had similar results.
While the National Weather Service indicates such levels of rainfall are equivalent to a 25- or 50-year storm, lifelong residents of Captain Cook said they had never seen anything like it, especially two years in a row.
"A lot of these things that are coming to light are showing us what we need to fix," Sumada said.
Although no specific reason for the changing runoffs has been identified, residents at a series of public hearings in the last two weeks pointed to development, especially grading and building upslope.
Madelyn Barrea told county officials that new concrete structures on property adjacent to her Cook's Landing home have added to flood and erosion problems.
A drainage ditch running along the border of her property has widened from four feet to 12 feet and is beginning to undermine her fence, she said.
Sumada said the new study will help the county pinpoint problem areas, which can be addressed through better drainage systems and tighter regulations for individual property owners and developers.
"We are working toward looking at the bigger impact, rather than individual homes," he said.
Federal Emergency Management Agency floodway maps date to the 1970s and are obsolete, especially for the Puna and South Kona districts, which have seen the most construction in the last couple of decades, Sumada said.
According to U.S. Census figures, the Puna District population jumped to more than 31,000 in 2000 from 11,751 in 1980. In South Kona the number rose to 8,589 from 5,914 during the same time.
Funding for the study, which could top $10 million for the entire island, is not yet secured, Sumada said.
The initial $1.5 million to study the three Captain Cook neighborhoods likely will come from the county's coffers, but federal funding and assistance from the Army Corps of Engineers might also be made available.
State Rep. Bob Herkes (D, Puna-Kau-Kona) said he is waiting for a final dollar figure before he takes the request to the federal level.
Sumada said he hopes to have that information by year's end.
County Councilwoman and Captain Cook resident Virginia Isbell also is considering a bond to help cover costs of the study.
Isbell has been concerned about the runoff issue for several years not just because of its impacts on homes, businesses and farms, but also for environmental reasons.
"We have to realize whatever we do on land will eventually end up in our ocean," she said.