Though Irene spared Rhode Island from major damages, save for the inconvenience of anywhere from 12 to 168 hours without power and the hefty cost to remove sand from roads and parking lots and put it back on the beach, weather events such as tropical storms and hurricanes do have the potential to cause significant harm to the lynchpin of the state’s tourism economy: our beaches.

Given the importance of the Ocean State’s beaches to the tourism economy, the maintainance — and rebuilding, when necessary — of our beaches seems like a no-brainer.

Storms such as Irene, currents from inlets and sea level rise cause beaches to erode. A beach can all but disappear after a Nor’easter or an El Nino-fueled storm. Coastal states and communities rely on the process of replacing sand — what the Army Corps of Engineers calls “beach nourishment” — to maintain tourist traffic, protection of coastal property and the continued health of coastal economies.

But some environmentalists say nourishment doesn’t last, is environmentally questionable and is bad fiscal policy.

Beach nourishment can have drastic effects on habitats. Sessile organisms such as barnacles can be immediately killed when buried in new sand. Seafloors can be compromised. Special care must be taken to ensure that replacement sand is similar in grain size and chemical composition to that of the target environment, and contains no non-native species or substances that may be toxic to native wildlife. Native plants and algaes can be affected by a short-term lack of available light associated with the dredging and depositing of sand. Newly deposited sand can harden and rob birds and sea-borne reptiles of nesting areas.

Some beach-nourishment projects have gone tragically awry, most notably in Hawaii, on the island of Maui.

A project at Sugar Cove transported upland sand to the beach. The sand was of a finer grain than the native sand and when it washed out it smothered the coral, killing it and many of the organisms that call the coral home. Another project, intended to slow rather than halt erosion, used sand-filled tubes as groins to retain the beach sand. The project saw the tubes and their anchors break free and destroy a nearby reef.

The U.S. government, through the Army Corps of Engineers, pays 65 percent for the initial project construction and 50 percent of the maintenance costs for the next 50 years, with state and local funding carrying the remainder of the cost of the replenishment. Opponents of beach replenishment argue that federal subsidies simply make people in landlocked states pay to protect coastal residents’ and businesses’ beachfront properties.

According to a 1998 study by Duke University’s Developed Shoreline program, an estimated $3.5 billion had been spent on 1,305 beach replacements since 1965, at an average of $5.7 million per mile of beach. The Army Corps of Engineers cites much lower figures, but spends about $150 million a year on beach replacement.

The real economic hitch in beach-nourishment projects is that they’re only good for 3 to 10 years. After that, it’s re-nourishment time. As the cost of these projects inevitably goes up, unfortunately, that 3-to-10-year window doesn’t show signs of changing. A severe storm can wipe out a beach overnight. In an age of more frequent and violent weather patterns, it can be assumed that beaches will be destroyed on a more frequent and violent basis, making beach replenishment necessary more often.

Coastal Resources Management Council (CRMC) officials recently toured, by boat, damaged waterfront areas with officials from the Federal Emergency Management Agency (FEMA).

“Everywhere, you have a lot of overwash,” said Janet Freedman, a coastal geologist with CRMC.

Easton’s Beach in Newport, along with much of the South Shore to Westerly, experienced significant movement of beachfront and dunes. Marsh grass was buried on Misquamicut and along the west side of the Charlestown Breachway camping area.

Freedman’s overall assessment was that it could have been worse. “That’s what dunes are supposed to do,” she said. “It’s the first line of defense in a storm.”

The real culprit in erosion is development. Beaches naturally move and shift. Beach houses, hotels, roads and other structures interfere with the movement of beach sand. Beach sand trying to move in from the ocean gets jammed up against man-made structures and has nowhere to go but out to sea. As a result, replenished beaches erode again. The only permanent solution is to moving buildings away from the beach. The cost of beach nourishment is relatively low in comparison to the cost of moving infrastructure.

Attempting to prevent erosion by building seawalls, groins and jetties is futile, and is illegal in Rhode Island. Seawalls accelerate erosion by giving the sand nowhere to go but back out to sea. Groins, jetties and man-made channels can disrupt natural currents that carry sand from beach to beach, which may save the sand on one beach, while starving another. History has shown that building barriers only delays the inevitable.

“It might protect your property, but it might harm adjacent properties,” Freedman said.

Jon Boothroyd, a respected local geologist, favors beach replenishment on public beaches, parking lots and roads. Help, he said, is needed to keep fixed, man-made structures operational, if only until a bigger storm wipes them out.

He opposes planting beach grass and trees to limit sand migration, which naturally pushes inland. Building sea walls and other artificial aids also shouldn’t be relied on to protect buildings and undeveloped habitats, Boothroyd said.

Freedman agreed. “If it’s a natural area, leave it alone,” she said.

Replenishment of Rhode Island’s beaches, luckily, won’t be needed in the aftermath of tropical storm Irene. Lost beach fronts are already returning on their own and may be at pre-storm capacity within a month, according to Freedman.

“The sand is coming back,” she said.