Meander Growth in Artificially Straightened Streams

Two rivers near Ames, Iowa, which were artificially straightened in 1900, are developing a meandering pattern. Meander amplitudes and wavelengths and channel widths were measured on aerial photographs taken in 1939, 1953, 1958 and 1966. Linear regressions between meander parameters and time, distance downstream from a bend, channel width-depth ratio, bank materials and discharge indicate that the rate of meander development decreases with distance from a bend in the channel, that meander amplitude increased more rapidly with time than does meander wavelength, that meander amplitude increases most rapidly in channels with low width-depth ratios and meander wavelength increases most rapidly in channels with high width-depth ratios. Bank materials and discharge did not provide close correlations. Very wide channels cut into sands did not develop meanders because excess energy was expended in moving bedload. Channels which did meander approximated in most cases the behavior predicted by the laboratory channels of Friedkin