The pounding that Hurricane Hermine's waves delivered to Pinellas County's beaches this week may result in the worst beach erosion this decade, according to the county's top beach expert."We're expecting it to be greater than the damage done by Tropical Storm Debby in 2012," Andy Squires, head of the county's coastal zone management office, said Friday.The storm has made tides about a foot higher than normal, he said, which makes it difficult to assess the damage accurately. Once that subsides, a University of South Florida team will survey how much sand the beaches lost, he said. They may make a report in 10 days.But the early indications aren't good.On Sunset Beach and Pass-a-Grille, waves were washing over the dunes, said Hilary Stockdon of the U.S. Geological Survey office in St. Petersburg, lead author of a study on erosion of Florida's beaches. On Indian Shores, water was pushing through a low area between the condominiums. "The waves and the surge were chewing away at the dunes," Stockdon said. "The dunes take longer to recover than the beaches themselves."And Squires said he received reports of waves topping seawalls in Belleair Beach. At the north end of Redington Beach, the water sloshed right up to the seawall, he said, and Fort De Soto's North Beach was "hit pretty bad — the water was well into the trees."Albert Carzola, 69, from Lancaster, Pa., has been vacationing with his family this week in a house on Indian Rocks Beach. On Friday, he and wife, Alison, also 69, said about 10 feet of the sand dune in front of their rented home was eroded by Hermine.Before the storm, "we could walk all the way out to that buoy," Carzola said, eyeing a small white marker bouncing violently in the waves about 100 yards away.Honeymoon Island State Park Manager Peter Krudler said his staff hadn't yet been able to assess the extent of erosion there. Honeymoon Island is the state's most popular park, attracting more than 1 million visitors a year.Pinellas beaches have been battered by storms before. In 2006, Tropical Storm Alberto cut 40 feet off Indian Rocks Beach. The No Name Storm of 1993 washed away as much as 70 feet of Upham Beach. In 2012, gulf beaches from Pinellas down to Charlotte County lost about 10 to 15 feet of sand to Debby.Pinellas' world-famous beaches help drive Pinellas County's tourism and real estate sectors. The problem is that the 11 barrier islands where those beaches exist are not fixed in place. They move, waxing here, waning there, pushed and pulled as the waves wash away their sand.And as with all Florida beaches on the Gulf of Mexico, they are extremely vulnerable. The 2012 U.S. Geological Survey study led by Stockdon found that 70 percent of gulf beaches are vulnerable to erosion during even the weakest of hurricanes, and 27 percent are likely to be completely inundated.To cope with the beaches' repeated loss of sand, the government goes out and gets more using taxpayer money. Engineers have been using new sand — dug up offshore and pumped to the land — to boost the size of beaches since 1922, when Coney Island needed enhancement.Since then, more than 300 major renourishment projects have been pursued nationwide, dumping a total of 517 million cubic yards of sand on the country's waning beachfronts, according to a study by the National Oceanic and Atmospheric Administration.Florida's beaches have reaped the greatest number of federally funded renourishment projects. Thirty-five of Florida's 67 counties have used taxpayer money to artificially enhance their beaches. Pinellas County's beaches have been renourished repeatedly since 1966. Sand Key, Treasure Island, Long Key and Honeymoon Island were all renourished in the last four years, Squires said.On Friday, longtime Indian Rocks Beach resident Skip Hodge, 59, walked barefoot along the shore nearby, looking at how much the surging water had chewed up from the renourishment programs."Nature's taking it back," he said.Times staff writers Zach Sampson, Tracey McManus and Piper Jones Castillo contributed to this report.