Estimation of Probable Maximum One Day Duration Rainfall for Khurda Region

The knowledge of probable maximum one day rainfall for a given region corresponding to return periods varying from 2 to 100 years is essential for crop planning and designs of minor and major hydraulic structures. The probability analysis for maximum one day rainfall of Khurda region is done by different probability distribution methods (log normal 3-parameter, pearson method, log pearson, weibull, generalized pare to distribution and log normal) by taking the rainfall data of 25 years(1991-2015) through FLOOD - frequency analysis software. Amongst them, log-normal 3-parameter method was found to be best fit based on chi-square and RMSE values 4.5 and 0.03328 respectively. The rainfall at 90%, 75%, 50%, 25% and 10% probability levels are determined. The plotted position of maximum one day precipitation was also tested through Chow method. The designed return period is calculated through Gumbel’s equation. The observed one day maximum rainfall during period of analysis is 400.3 mm with standard deviation and co-efficient of variation 71.06 mm and 0.552 mm respectively. The values of maximum precipitation by log-normal 3-parameter method and Chow frequency factor method are very close to each other and from these two methods, either can be implemented for design of different soil and water conservation structures.