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A comparative study of five popular frequency distributions and three parameter estimation methods was conducted by using 92 Louisiana rainfall data sets. Computed results showed that the log‐Pearson type 3 (LPEAR3) distribution was the most appropriate probability distribution for the Louisiana rainfall data. Furthermore, the method of moments was found to be the best estimation method for the LPEAR3 distribution based on descriptive performance indices. A first‐order error analysis was performed on the parameters of the LPEAR3 distribution. Computed results showed that the predicted quantiles of the LPEAR3 distribution were most sensitive to the population mean and relatively insensitive to the coefficient of the skewness of the distribution.

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A generalized skew map for Louisiana streams was developed using data from Louisiana, Mississippi, Arkansas, and Texas with 20 or more years of annual flood records. A comparison between the newly developed Louisiana Generalized Skew Map (LGSM) and the generalized skew map recommended by the U.S. Water Resources Council (WRCGSM) was performed. The mean square error for the LGSM was 16 percent less than that of WRCGSM in direct application of the two maps. Performance of the new map was compared with the WRCGSM and with a regional analysis procedure through its application to the Log Pearson Type 3 (LP3) distribution. Two-thirds of the stations tested had lower standardized root mean square deviations (SRMSD) by a narrow margin using the skew coefficients obtained from LGSM instead of WRCGSM. The regional analysis also performed as well as the LGSM in terms of SRMSD. Thus, it was concluded that bothLGSM and the regional analysis provide a more reliable tool for flood frequency analysis for Louisiana streams with short annual flood records. (KEY TERMS: Generalized Skew Map (GSM); regional skew coefficients; flood frequency analysis; Log Pearson Type 3 distribution.)