THRESHOLD STOCHASTIC MODELS OF LOW FLOW

M. V. Bolgov and I. A. Filippova

An approach is considered to describe hydrological conditions of rivers in low-flow periods by calculating the characteristics of outliers of a random flow pro¬cess. The distribution of the duration of low-flow periods determined as the periods of sreamflow decrease below a specified level (threshold) is proposed as the major characteristic. Parameters of this type characterize, in integral terms, flow variations in the low-water period and are most informative for solving the problems of estimating ecologically permissible changes in water conditions.