Surface erosion, sediment transport, scour, and deposition have been the subjects of study by engineers and geologists for centuries, due to their importance to economic and cultural development. Most ancient civilizations existed along rivers in order to use the water supply for irrigation and navigation. All rivers carry sediments, due to surface erosion from watersheds and bank erosion along the river. Our understanding of the dynamic equilibrium between sediment supply from upstream and a river's sediment transport capability is important to the success of river engineering design, operation, and maintenance.