STATISTICAL ANALYSIS OF RAINFALL DATA AND ESTIMATION OF PEAK FLOOD DISCHARGE FOR UNGAUGED CATCHMENTS

Abstract

Estimation of Peak Flood Discharge (PFD) at a desired location on a river is important for planning, design and management of hydraulic structures.For ungauged catchments, rainfall depth becomes an important input in derivation of PFD.So, rainfall depth can be estimated through statistical analysis by fitting probability distribution to the rainfall data.In the present study, the series of annual 1-day maximum rainfall derived from the daily rainfall data recorded at Manjuhi Khad is used for estimation of 1-day extreme rainfall adopting Extreme Value Type-1 (EV1) distribution.Maximum Likelihood Method (MLM) is used for determination of parameters of the distribution.Anderson-Darling is applied for checking the adequacy of fitting of the distribution to the recorded data.The estimated 1-day extreme rainfall obtained from EV1 distribution is used to compute the 1hour maximum value of distributed rainfall that is considered as an input to estimate the PFD by rational formula.The study suggests the estimated PFD could be used for design of flood protection measures for ungauged catchments of Bhul and Manjuhi Khad, Himachal Pradesh.