COMPARISON OF RAINFALL ESTIMATES OF EV1 AND LP3 DISTRIBUTIONS FOR ESTIMATION OF PEAK FLOOD DISCHARGE USING RATIONAL METHOD

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 basin, rainfall depth becomes an important input in derivation of PFD.
So, rainfall depth can be estimated through Extreme Value Analysis (EVA) by fitting of probability distribution to the series
of recorded rainfall data. In the present study, Extreme Value Type-1 (EV1) and Log Pearson Type-3 (LP3) distributions
are adopted for estimation of rainfall at Dhaulakuan rain gauge station. Maximum Likelihood Method (MLM) is used for
determination of parameters of the distributions. Goodness-of-Fit tests such as Anderson-Darling and Chi-square are
applied for checking the adequacy of fitting of probability distributions to the recorded data. Root mean square error is
used for the selection of most suitable distribution for estimation of rainfall. The estimated 1-day maximum rainfall
obtained from EV1 distribution at Dhaulakuan station is used to compute 1-hour maximum value of distributed rainfall
adopting CWC guidelines. The study suggests the estimated PFD from rational method could be used for design of flood in
river protection works of Yamuna river basin.