Stage recorders have registered stream depths upstream (4.05 m) and downstream (3.98 m) of a culvert during a flood event. The 2 m by 2 m concrete culvert (square-edged entrance) is 15 m long and has a slope of 3.0 percent. Based on this information, determine the flood flow rate that passed through the culvert. Assume the stream depths are measured above the culvert inverts on the upstream and downstream ends.