South Florida high tides are swamping seawalls, eroding beaches

Blame our high water on the sun, moon, heavy rain and offshore storms

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By Robert Nolin

October 6, 2008

The causes are as cosmic as the tilt of the earth and as common as an onshore breeze. The effect is the exceptionally high tides now stacking up water along South Florida's coastline, swamping low sea walls, eroding beaches and forcing boaters to adjust dock lines.

"It's probably a foot higher than usual," dockmaster Ron Dery said of the high water mark at Rybovich Marina in West Palm Beach.

Water managers say autumn tides, always the strongest of the year, are inching even higher this month because of persistent onshore winds from passing storms compounded by heavy rains. Closed canal gates to prevent saltwater tidal flow from flooding inland waterways are also a factor.

The high tides are sloshing against sea walls mostly along coastal waters such as the Intracoastal Waterway. But some canals are also extra swollen.

"It's a regional issue. It's the ocean, so it's affecting everybody," said Eric Swartz, lead meteorologist with the South Florida Water Management District. Fall tides, he said, are typically a foot higher than other tides during the year.

"I've never seen the water so high," said Greg Smalter, a four-year waterfront resident who frequently kayaks the Intracoastal and connecting waterways in southern Broward County. "I can't get under the bridges under these conditions."

The gravitational pull of the sun, and that of the moon, cause the tides. Fall tides are the most powerful of the year because the sun, rather than being at an angle to the earth, is aligned with the equator during September, October and November. Also, the earth is tilted on its axis closer to the sun.

"Every year it's the same thing; the attraction of the sun on the earth is the strongest in the fall," said Laurent Cherubin, an oceanographer with the University of Miami's Rosenstiel School of Marine and Atmospheric Science.

Propelling this season's tides to new heights are the same onshore winds that sent waves breaking across the A1A in Fort Lauderdale earlier this month. Those winds originated with Hurricane Kyle and another storm off the Carolinas.

"You had not only the seasonal higher-than-normal tides, but complicating that was strong onshore winds," said Susan Sylvester, the water district's director of operations. "We had everything converge."

Heavy rains — North Perry Airport in Pembroke Pines had 6.34 inches over the weekend, meteorologists said Sunday — also contributed.

"All that rain will raise the water table and, combined with a higher than normal high tide, could result in some minor flooding," said Robert Molleda, warning coordination meteorologist with the National Weather Service in West Miami-Dade County.

The water district has been dumping water from swollen Lake Okeechobee, but that flow has not been a major factor. "Our discharges are trivial compared to the force of a storm pushing in a higher than normal tide," Sylvester said.

Don't expect South Florida's waterways to subside soon. "The next full moon is the highest tide of the year," said Swartz, the water district's weatherman. That moon was called the Hunter's Moon by American Indians, who marked it as the time to hunt fattened deer. It will rise at 6:38 p.m. on Oct. 14.

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