Officials in northeastern Iowa are cleaning up in the aftermath of a July 24 dam failure, and early analysis indicates an earthen berm next to a section with concrete spillways was overtopped and eroded away when the rain-swollen, 9-mile-long Lake Delhi overwhelmed it. Photo: AP/WideWorld Earthen berm by spillway was overtopped and eroded. “It appears at this point that there was just a lot more water than the dam was designed for,” says Lori McDaniel, supervisor of floodplain management and dam safety programs for the Iowa Dept. of Natural Resources. Further, she says the concrete spillway next to the berm
Arch dams, classically curved monoliths situated in narrow valleys, are not as common as other types of dams, such as embankment dams and gravity dams. ENR takes a look at some of the biggest arch dams in the world, both completed and under construction.