Statistical Models for Flood Frequency Estimation of the Mississippi and Yazoo Rivers

Abstract

This paper investigates the application of the theory of extreme values to predit the magnitudes of annual floods for the Mississippi and Yazoo rivers based on maximum annual levels of the rivers between 1925 and 1975. First, the data were tested to establish an initial probability distribution of the yearly extreme values. It was found by means of goodness of fit tests that both the normal distribution and the log-normal distribution adequately describe the extreme probability distributions for both rivers. Then by using techniques developed by Cramer, the expectations and variances of the mth extremes were calculated. From the estimates of these two parameters, probability predications of the level of floods for any return period may be obtained. The paper presents predicted values of floods for return periods of 100, 200. and 300 years.