Determination of the normal rates of planar deformations and depths of uniform river stretches

Conclusion

It has recently become obvious that without a reliable calculation of the bed-load discharge, hydraulic methods of calculating and predicting channel deformations cannot be created [8]. At the same time, it is considered that during the past 30–40 years the results of calculations by the existing recommendations have been repeatedly compared by various authors in the USSR and abroad, and a difference in individual formulas by tens and hundreds of times has invariably been found [8, 9].

Hence the advantage of using probabilistic methods of calculating planar and depth deformations [3–5], for using which knowledge of the discharge and components of the sediment balance is not necessary, is clear, and the hydrodynamic effect of the flow on erosion of river channels should be regarded only as an internal link in cause-and-effect relations, since the hydrodynamic forces themselves are subordinate to the conditions of the water regime and act in a medium subordinate to the laws of geomorphology [9, 11].

Probabilistic methods of determining river channel deformation rates based on morphology and consideration of the water regime are at present approximate, but also quite simple. They are valid for calculating the normals of deformations for periods measured in decades, i.e., for periods during which it is legitimate to expect years differing in wetness and sediment discharge. These methods can be used for preliminary estimates of river deformations under design conditions. The approximate values of the normals of the rates (intensity) of planar and depth deformations required for probabilistic methods can be determined by the methods examined here. Investigations into improving the use of probabilistic methods should be continued.