Hydraulics And Hydrology In Action

If you are going to build a fence across a stream bed, listen to the civil engineers (via nc links):

Amidst recent reports that detail just how harmful the United States border barrier is to local wildlife and their habitats, rainwater knocked down 40 feet of the fence in Arizona last Sunday night. The stretch of fence that washed away was part of a 5.2 mile mesh barrier that was built between 2007 and 2008. Though it is the first time this particular fencing has fallen, it came as no surprise to officials at Organ Pipe Cactus National Monument, where the fence is located. When Organ Pipe expressed their concern with the proposed design for the barricade before its completion, Border Patrol unsurprisingly issued a final environmental assessment that said they found that it would have no significant impact. They added that, despite the claims of Organ Pipe officials, it would not cause flooding. They were wrong.
Lee Baiza, Superintendent of Organ Pipe Cactus National Monument, told the Arizona Daily Star, “The fence acts as a dam and forms a gradual waterfall. … The water starts backing up and going higher. The higher it gets, the more force it has behind it.”
It only took 2.5 inches of rain to wash away the fence, and because Baiza says bursts of strong rain are common in the area, it probably won’t be the last time such an incident occurs. Matt Clark, the Southwest representative for Defenders of Wildlife, says this is an example of consequence of Homeland Security’s disregard for expert advice in an effort to quickly erect border fences.

Whodathunkit?