While residents along the East Coast of the U.S. make emergency preparations and evacuate as Hurricane Floyd heads inland, coastal scientists and policy makers worry that rising sea levels and more intense storms are likely to cause an increasing number of disasters in coastal areas. Population growth is booming along U.S. coasts, in part because of government policies encouraging development, according to some experts. Within a few years, most Americans will live in coastal counties, some demographers say. The property rights movement, as well as the expectation that the federal government should be extremely generous with disaster victims, have intimidated government officials from limiting development and redevelopment, says Rutherford H. Platt, a professor of geography at the University of Massachusetts at Amherst. Meanwhile, the World Wildlife Fund warned yesterday that climate change could cause more super-hurricanes like Floyd.