Flood Frequency Analysis of the Par River : Western India

Abstract

An evaluation of the effectiveness of flows depends on the magnitude and frequency of the events than mean discharges. Magnitude-frequency analysis is one method that identifies the hydrological and geomorphological importance of these events quantitatively, particularly the frequency of flood events of various magnitudes. Therefore, an attempt has been made to understand the magnitude and frequency characteristics of floods on the Par River on the basis of available annual peak discharges and field data. The Annual Maximum Series (AMS) data were available for the Nanivahial site on the Par River for 49 years. To estimate discharges of a given return period, frequency distribution is compiled from a data series of extreme events. By using Gumbel Extreme Value type I (GEVI) probability distribution, peak flows have been estimated for different return periods. The distribution has also been employed to estimate the recurrence interval of mean annual peak discharge, large flood and actually observed maximum annual peak discharge. The magnitude-frequency analysis based on GEVI distribution reveals that the mean annual peak flood has a recurrence interval of 2.33 years, large flood has 6.93 years and maximum peak discharge has 185 years. Two general conclusions emerge from the analyses. First, the river displays extraordinary hydrologic characteristics of a flood-dominated river. Second, large floods are relatively frequent. This fact suggests that large-magnitude events have an important role to play in the bedrock channel morphology of the Par River.