ABSTRACT
The normal distribution is used in frequency analysis for fitting empirical distributions to hydrological data, and in simulation of data. In many statistical parameters are approximately normally distributed, the normal distribution is often used for statistical inferences. The absence of information about the distribution of floods and economic losses associated with the design of flood reduction measures, the use of the normal distribution is better than other distributions such as extreme value, lognormal or Weibull. There are two methods for calculating the standard error by the method of moments. The first method involves the evaluation of the standard error for the logarithmic transformation of the observations. The second method involves the direct application of the standard error formula to the observations. The three–parameter lognormal distribution is similar to the LN distribution except that x is shifted by an amount which represents a lower bound.
