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The transformations (i) SMEMAX (ii) Modified SMEMAX (iii) Power and Probability Distributions (iv) Weibull (a,P,y) or Extreme value type 111 (v) Weibull (a,P,O) (vi) Log Pearson Type 111 (vii) Log Boughton are considered for the low flow analysis. Also, different parameter estimating procedures are considered. Both the Weibull and log Pearson can have positive lower bounds and thus their use in fitting low flow probabilities may not be physically justifiable. A new derivation generalizing the SMEMAX transformation is proposed. A new estimator for the log Boughton distribution is presented. It is found that the Boughton distribution with Cunnane's plotting position provides a good fit to low flows for Virginia streams. Downloaded from https://iwaponline.com/hr/article-pdf/16/2/105/2359/105.pdf by guestPower Transformation -This transformation was first proposed by Box andCox (1964), andChander et al. (1978) used this transformation for flood frequency analysis. In a paper by Kumar and Devi (1982), the power transformation was applied to the frequency analysis of low flows for one station. The power transformation is formwhere: z is normally distributed with mean M, and standard deviation S,; y is the original sample value; h is a parameter of transformation. Also, y can be replaced by (y+ k) for y >k. Downloaded from https://iwaponline.com/hr/article-pdf/16/2/105/2359/105.pdf by guest + Z,) 12 Z1 largest (chosen arbitrarily). Considering Fig. 1 for f o r It is noted that Z1 = 22, for Z, = 0. For this special case the transformation given by Eqs. (4) and (5) becomes for X < X < X m S --Downloaded from https

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