Abstract

M. A. B. Barkotulla, M. S. Rahman and M. M. Rahman

Probability distributions were to predict rainfall status of various return period estimating one day and two to
seven consecutive days annual maximum rainfall of Boalia, Rajshahi, Bangladesh. Three commonly used
probability distributions (viz: Normal, Log Normal and Gamma distribution) were tested to determine the best
fit probability distribution using the comparison of chi- square values. Results showed that the log-normal
distribution was the best fit probability distribution for one day and two to seven consecutive days annual
maximum rainfall for the region. Based on the best fit probability distribution the maximum rainfall of 116.15,
161.09, 190.14, 205.96, 220.37, 234.66 and 245.21 mm was expected to occur 1, 2, 3, 4, 5, 6 and 7 days
respectively at Boalia (Rajshahi City Corporation and surrounding areas) every two years. For a recurrence
interval of 100 years, the maximum rainfall expected in 1, 2, 3, 4, 5, 6 and 7 days were 290.24, 406.49, 544.08,
558.56, 600.33, 631.28 and 633.89 mm respectively. The results of this study would be useful for agricultural
scientists, decision makers, policy planners and researchers in order to identify the areas where agricultural
development and construction of drainage systems in Boalia as one of the major factors causing flooding
should be focused as a long-term environmental strategy for Bangladesh.