He argued against putting condos, hotels and other heavy infrastructure on vulnerable coastal landscapes. Environmentalists applauded; many others didn’t.
Orrin H. Pilkey, a coastal geologist whose blunt and often successful arguments against sea walls and other armor on the saltwater beaches of the United States won him reverence from environmentalists and condemnation from developers and politicians, died on Friday at his home in Durham, N.C. He was 90.
His daughter Linda Pilkey Jarvis confirmed the death.
As a professor at Duke University and in books, newspaper articles, town hall meetings and television documentaries, Dr. Pilkey made the case that it was a mistake to put condominiums, hotels, roads or other heavy infrastructure on unstable, vulnerable landscapes like beaches — especially barrier islands, the thin ribbons of sand that line most of the U.S. coast from Cape Cod to Mexico.
Sea walls or other coastal armor may protect buildings on an eroding beach, he said, but almost always at the expense of the beach. When the sea reaches the wall, the beach is drowned.
And he had little good to say about an alternative — “nourishing” eroded beaches with multimillion-dollar infusions of pumped-in sand.
Although many beach towns would be beachless without these projects, to Dr. Pilkey they were disruptive, harmful to the environment and prone to washing out, often with stunning speed. He scorned the cost-benefit calculations used to promote them as “Useless Arithmetic,” as the title of his 2007 book on the subject put it.
Backers of such projects now typically describe them upfront as “sacrificial” — expected to fail in a storm, but designed to protect the buildings behind them. But, as Dr. Pilkey argued, in the absence of development, beaches simply shift in response to sea-level changes and heavy weather.