Statistical evaluation of parameters of the river Small Cheremshan

On the basis of data on annual, monthly and daily water consumption of the Malyi Cheremshan river, curves of security, smoothing and extrapolation of which are carried out by two types of distribution - three-parameter and lognormal. If the data are sufficient, both types of distribution provide estimates of the same order with a deviation not exceeding the errors of the original data. But the lognormal distribution is preferable in view of the greater simplicity of the method of estimation and the better predictive ability, especially at the ends of the curves, compared with the three-parameter gamma distribution.