River Meanders Theory Of Minimum Variance By W B Langbein And L B Leopold

River meanders - theory of minimum variance, by W.B. Langbein and L.B. Leopold

River Meanders--theory of Minimum Variance

The geometry of a meander is that of a random walk whose most frequent form minimizes the sum of the squares of the changes in direction in each unit length. Changes in direction closely approximate a sine function of channel distance. Depth, velocity, and slope are adjusted so as to decrease the variance of shear and the friction factor in a meander over that in an otherwise comparable straight reach of the same river.

Theoretical Morphodynamics: River Meandering

This monograph discusses the mechanics of Meandering Rivers with the help of the mathematical and modeling tools built up in the previous monograph of the same Authors (monograph 1 of the present series). After introducing the reader to the ubiquitous character of meandering streams, we discuss the hydrodynamics of curved channels with fixed beds and banks. Next, we extend the analysis to account for the mobile character of the bed and show that it gives rise to the alternate sequence of riffles and pools that characterize river meanders. Allowing for the erodible character of the river banks then allows to build up a rational theory of meander formation able to explain most of the features observed in nature: meander growth, migration, skewing, multiple loops, cutoffs and meander belts.