Positive aspects of studying the sedimentations in reservoirs through the natural experiments

Aim: The process of the sediment accumulation in reservoirs stops after the silting prism is formed on the body of equilibrium bed, by means of which the river can transport a full range of sediment downstream. Presently, there is no approved method for forecasting the parameters of the silting prism and the equilibrium bed. In order to study the process of the silting prism formation and the equilibrium channel forecasting the field experiments were carried out on small mountain rivers of Georgia. Methodology: Methodology of the natural experiment implementation was created. For the analysis of the obtained results the methods of mathematical statistics and differential calculus were applied. Results: The experiments showed that equilibrium bed is formed much higher than the initial position of the riverbed causing a serious threat of catastrophic inundation in case of flood. It was found that final result of the reservoir silting is an accumulative terrace, where an equilibrium channel is produced. Length of the train is a function of the maximum flow discharge, the deposit of runoff, diameter of bottom sediment and initial inclination of riverbed. Fractional distribution of the sediments into silting prism is determined by the type of the reservoir regulation and the intraannual distribution of the fluvial sediments. Interpretation: The mechanism of riverside destruction by waterflow is considered as a random process, which depends on both the effect of flow rate and riverside stability. Vulnerability, the characteristic of the riverside is taken as the indicator of this process with respect to such influence, and famous model "load stability" from the theory of reliability is used for its identification.