Developing an Empirical Model for the Estimation of Peak Discharge in Some Catchments in Western Iran

Peak discharge is one of the basic parameters in the design of hydraulic structures. There are various methods for peak discharge determination. Regional flood frequency analysis is based on physical, climatological and hydrological characteristics of basins. The objective of this study is to examine different models for the estimation of quantiles for some catchments in western Iran (namely: Gharehsoo, Gamasiab, Kashkan, Seimareh, Sezar and Abshineh) for which only maximum daily mean discharge data exist. In this research, peak and maximum daily mean discharges for 11 stream gauging stations were collected for a 21-year period. The ratio of these two discharges (R) and mean and standard deviations of peak discharges and maximum daily mean discharges were computed. Catchment characteristics including catchment area, catchment perimeter, main channel length, mean elevation, mean slope equivalent rectangle length, circular ratio, Gravelius coefficient, drainage density, time of concentration, relief ratio and diameter of the circle having equal area with the catchment were computed. Linear regression analysis was performed between independent variables of the catchments and mean standard deviation of the parameter “R” to develop a relation. The results of this study can be applied to the estimation of extreme flow values for non-recording stream gauging stations (daily reading sites).