I have a roadway with 4 bridges through a large channel and floodplain. My water surface elevation is approximately 3′ above the lowest point in my roadway, but I am not getting any weir flow. My velocities in the channel are 2 – 7 fps and 0.75 to 1.5 in the overbank areas of the roadway cross section, so there should be some movement of water across the roadway.