Coastal Flood Plain and Entrenchment

Fremont Weir and Yolo Bypass are shown in this photograph. It is apparent due to the flat Floodplain that the flood prone area width, found at twice Bankfull Elevation, extends for a significant distance beyond the Bankfull Width. The Bankfull height is approximated at the area of riparian vegetation.

Large flood prone widths lead to large entrenchment ratios. Additional cursory information on slopes in this region of the river suggests that the channel could be a Rosgen E or a C type. Without a 50% diameter class on the Reach wide substrate material, little can be inferred about its numerical classification, and it remains a Level 1 characterization.

Image courtesy of NOAA