According to meteorologists, the flooding was a result of a "bomb cyclone" which swept across the US from the Rockies to the Central Plains last week. The difficulties were exacerbated by the frozen ground, which meant the water could not drain away.

Several states, including Iowa, Nebraska, Wisconsin and South Dakota have declared a state of emergency.

Pete Ricketts, the governor of Nebraska, said the storms had caused "unbelievable devastation" with the state suffering the worst floods in half a century.