Decisions To 'Harden' Hawaii Beaches Can Be Disastrous

This fall is the 40th anniversary of the founding of the Surfrider Foundation. Now an international organization, it has worked hard to educate decision makers about the futility of trying to hold back the ocean.

Hawaii decision makers are fairly uneducated about coastal issues. Decisions to “harden” our beaches can be disastrous.

The majority of Hawaiian beaches are eroding. The first response to save an eroding beach is to put up a big wall of rocks or sand bags, concrete, whatever. Unfortunately, these seawalls do the opposite of what is expected.

Beach sand erosion increases at a faster pace. The surf ricochets off the wall and sends the beach sand back into the ocean. Thus, the public beach disappears.

Beach sand is a fluid process that changes with the seasonal surf direction. Human efforts to change the beach currents all have negative impacts of one sort or another.

A groin is a structure built perpendicular to the beach in an attempt to block the longshore current. It works great for one side of the groin, but the other side of the beach erodes away much faster. 

Worse still are breakwaters. A breakwater blocks the surf entirely and can cause a stagnant ocean such as Hilo Bay.

Engineers are now calling submerged breakwaters “artificial reefs.” To protect a military road on Oahu, a concrete breakwater just under the surface will be planted with coral seedlings. This “artificial reef” is the latest attempt to block the ocean waves

If nature wanted a reef, one would have grown there. A breakwater will destroy the recreational surf, cause stagnant beach water and disrupt all the nearby beach currents that move the sand back and forth.

Beachfront homes require permits to build beach-destroying armor, but the Hawaii Department of Transportation can streamline all the rules and call it an “emergency.”

Hawaii is full of state roads built along the beach. Rather than long term planning to move the roads away from the beach, the Department simply calls it an “emergency” and throws up a seawall.

On Kauai, there is a road in front of a proposed hotel (Coco Palms) where the plan is to build a seawall and a breakwater. This idea is even more misguided because, instead of concrete, the breakwater will be made of plastic with holes in it to trap the sand — a SandSaver. One big storm will wipe it out and there will be plastic all over the beach.

In Waikiki, the plan is “beach sand nourishment.” The plan is to take sand from offshore and bring it back to the beach. There are also a few groins proposed.

This is, perhaps, a nice short-term solution for all the expensive hotels, but the sand will have to be replaced on a regular basis. Sea level rise is a long-term problem that will catch up to them eventually.

Beach sand is a complex ecosystem, attempting to manipulate its natural movement is a folly, often doing more harm than good.