River Besearch Institute, West Bengal, Calcutta.
Application of probability methods in different spheres of hydrology has been recommended by many eminent hydrologists. This serves many useful purposes and throws some light regarding the nature of flow to be expected in the river during the ensuing years as visualised from the past data. When daily discharge observations are available in a river over a number of years, it is possible to estimate the probable discharge at different probability levels. This may be sometimes preferred to the usual methods based on yearly peak or yearly maximum as here our estimate is based on larger number of observations. This paper outlines a method of estimating the probable discharge in a river from daily discharge observations by Slade’s log-normal function. The parameters are estimated by Maximum Likelihood Method and their large sample variances are also computed. The variances will give us some idea regarding the precision of the estimates.
