Embankments that encroach on floodplains are most commonly subjected to scour and erosion damage by overflow and by flow directed along the embankment to the waterway openings. Erosion can also occur on the downstream embankment due to turbulence and eddying as flow expands from the openings to the floodplain and due to overtopping flow.

The incidence of damage from flow along an approach embankment is probably highest in wooded floodplains where the right-of-way is cleared of all trees and where borrow areas are established upstream of the embankment. Damage to approach embankment is usually not severe, but scour at the abutments from the flow contraction may be significant if the abutment is not protected.

The potential for erosion along the toe of approach embankment can be minimized by avoiding extensive clearing of vegetation and avoiding the use of borrow areas in the adjacent floodplain. Embankment protection such as stone protection can be used, but stable vegetation on the embankment may suffice. Other measures that may be used are , pervious dikes of timber, or finger dikes of earthen material spaced along and normal to the approach fill to impede flow along the embankment.

The embankment may need to be protected if significant overtopping of the approach embankment is anticipated during the life of the crossing. The embankment can be protected with soil cement or revetments, rock, wire-enclosed rock, or concrete.

Preventive measures are also needed at some crossings to protect the embankment against wave action, especially at reservoirs. Riprap of durable, hard rock should be used at such locations. The top elevation of the rock required depends on storage and flood elevations in the reservoir and wave height computed using wind velocities and the reservoir fetch.