Scour and fill patterns in pool-rapid rivers

Abstract

Sediment carrying pool-rapid rivers are abundant in the United States. However, not much is known about the behavior of the pool beds. It is known that with an increase in the flow that sediment eventually is scoured from the bed and when the flow is decreased the bed elevation eventually increases, but what actually occurs before the final equilibrium bed configuration is attained can only be approximated. It is a reasonable assumption that the bed elevation fluctuates due to scour and deposition, until the final equilibrium bed configuration is attained. An approximate analysis of the scour and fill patterns of the pool-rapid river was made to predict the scour and fill patterns of pool-rapid rivers. A numerical model was analyzed to better account for what actually happens to the pools. The results of the analysis verified that when there was a change in the flow that the pool bed had fluctuated by scouring or filling, and that the time period until equilibrium would occur varied by several orders of magnitude.