Abstract

Channel-forming water discharge and its probability are important characteristics of river flow activity. Each interval of the channel-forming water discharge causes its own corresponding deformation degree at different structural levels (different characteristic features of the river bed type and river-bed forms). This fact gives us possibility to make a conclusion about river bed change using the data about change of the channel-forming water discharge.

At present, according to Prof. R.S.Chalov, the most problematic aspect of the procedure for the definition of such discharges is the statistical instability of their value for water discharges of small probability; and also a very rough estimate of bed-material load, moving both in suspension and by traction.

The aim of this work is to develop a procedure of creating the analytical expression of channel-forming discharges curve and to resolve a problem of statistical instability of maximums on this curve corresponding to discharges of rare occurrence probability.

This procedure assumes: firstly, use of analytical expression for smoothing the occurrence probability curve for daily water discharges; secondly, use of a lower rounding equation, determined within the field of the points of the suspended sediment concentration (SSC) to water discharge dependence for bed load estimation (bed-material load).

Keywords: channel-forming (effective) discharge, occurrence probability curves, bed-material transport, channel-forming discharges diagram