Overall Statistical Characteristics

The most commonly used statistical properties for analyzing stationary or non-stationary hydroclimatic time series are the sample mean y, variance s2, coefficient of variation cv. skewness coefficient g, lag-A' autocorrelation coefficient rk, and the spectrum g(f). Coefficients of variation of annual flows are typically smaller than one. although they may be close to one or greater in streams in arid and semiarid regions. The coefficients of skewness g of annual flows are typically greater than zero. In some streams, small values of g are found suggesting that annual flows are approximately normally distributed. On the other hand in some streams of arid and semiarid regions, g can be greater than one.

The lag-A- autocorrelation coefficient rk may be determined as rt=^ k = 0, 1.2

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