A Simple Analytical Design Method for Small Alluvial Channels

This paper presents an analytical design method for realignment of small alluvial channels with non-cohesive bed material. This method follows the general approach recommended by the U.S. Army Corps of Engineers and the Natural Resources Conservation Service. The realigned reach is designed to convey the same bankfull discharge and sediment load as a stable reach directly upstream. The length, slope, sinuosity and cross-sectional dimensions of the realigned reach are obtained from an analytical solution to Manning's equation for flow resistance and a simplified version of the Meyer-Peter and Muller equation for bed-load transport. The bankfull width and meander wavelength are obtained from geomorphic relationships for stable natural streams. Consequently, the realigned reach should have stable geomorphic characteristics that are typical of a natural stream in a similar setting.