Guide for Estimating Riverbed Degradation

Abstract

The rate and extent of riverbed degradation resulting from sediment interruption are determined by means of computer‐based numerical experiments. Momentum and continuity equations for water and sediment flows in a wide prismatic channel are solved numerically using a recently verified model for the bedarmoring process. The bed profiles for different times are found to be similar and are coalesced to a single normalized curve. The changes in bed levels and mean sediment size, and the length of degradation, determined from the numerical experiments, are correlated by multiple regression analysis to the independent dimensionless variables. The depth of degradation depends on the Froude number, the geometric standard deviation, and the normalized median size of the bed material. The proposed relationship for bed degradation is verified with the field data of Missouri River. The computation procedure is illustrated by an example.