River-Coast Interaction: Laboratory Simulation

The flow of a river into the ocean is often obstructed by a sand bar at the river mouth. The interaction of a river with the coast can be simulated in a hydraulic model with a movable bed. Use was made of the equation of continuity of sediment flow to arrive at similarity relationships. The method was used successfully for the Yaguez River in Puerto Rico. The results of the study indicate that water surface elevation in the river rises because of the obstruction of the bar at the river mouth. The highest water elevation occurs before the peak flow arrives at the mouth. Coastal structures were tested to minimize the water elevation. The method offers a useful coastal engineering tool but future work is needed to include the influence of waves.