Isle beaches deserve better policies

Hawaii’s leaders never seem to get a firm grasp on one problem, despite the fact that it literally surrounds them. It’s beach erosion, and the failure to deal with that simple fact of nature is evident in the way that Oahu in particular has developed: with too many buildings too close to the shoreline.

Now, in addition to the visual reminders of the process, there is a new set of data from the U.S. Geological Survey that measures just how fast Hawaii is losing its world-famous beaches. The hope is that this information will lead to better decisions where shoreline land use is concerned.

"National Assessment of Shoreline Change: Historical Shoreline Change in the Hawaiian Islands" is that study, which mainly based its measurements on aerial photographs tracing shoreline movements between 1910 and 2007.

The bottom-line news is sobering. About 70 percent of the beaches measured on Oahu, Kauai and Maui show a trend of erosion over the long term; 63 percent of them are showing ill effects in the short term. The sand at Oahu’s Kualoa Point is disappearing most rapidly, the beach shrinking by nearly 6 feet every year.

Property owners have tried to stave off the loss of frontage in various ways, from erecting sea walls and groins — which can affect intersect with currents in ways that actually produce sand erosion and accretion elsewhere — to piling up sandbags or planting shoreline vegetation. Kahala and Lanikai beaches are two spots where this has occurred, and it elicits complaints from beachgoers who say the landscaping encroaches on routes the public uses to walk along, or to, the beach.

The optimal answer is not to erect such barriers but to ensure that new shoreline building is set back an adequate distance. That has been the contention of experts in the field, including Chip Fletcher, a lead researcher in the study and University of Hawaii associate dean for academic affairs at the School of Ocean and Earth Science and Technology.

Building too close to coastlines damages the environment and exposes property to hurricanes, storms and rising sea levels, Fletcher said.

Adding to the urgency of the situation, of course, is the concern about climate change and rising sea levels. Global projections show a rise of about a foot by 2050, compared, for example, to a rise of 6 inches on Oahu over the past century.

Beach replenishment is an option, but despite the apparently successful project in Waikiki, it’s one that’s affordable only to very few.

The new information on beach erosion should harden government resolve to manage this precious resource with land-use regulations that accommodate nature’s reality.

On Maui — where the study notes that 85 percent of the measured beaches are eroding — a new building must be set back 50 times the annual rate of coastal erosion for the property, plus 20 feet.

Kauai has an even greater setback: 75 times the annual erosion rate, plus 40 feet.

Officials looking out for Oahu — where the setback is merely 60 feet for new lots and 40 feet for existing lots — would be wise to amend their planning approach.

The USGS research is part of that agency’s mission to monitor coastal change using consistent methods nationwide. The study itself does not include any recommendations for action, but anyone who reads it should derive a clear message: Building along the shoreline needs to be done with erosion concerns driving the planning decisions.