J.Env.Sci. Tech., Spring 2004, No.20



Probability Density Function Analysis using Event Mean

Concentrations in Urban Runoff



College of Environment , University of Tehran


College of Natural Resources, University of Tehran


University of Shiraz



 Keywords: Urban runoff, Gamma distribution , 2 Lognormal distribution , return period



Urban runoff has a large rate of various pollutants and destroys acceptor water resources and also damage environment . The management strategies for urban runoff pollutants controlling depende on identifying and analysing these pollutants . In this study the procedure for fitting , selecting and appropriate probability distribution function (pdf) for a runoff quality  constituent concentration in Isfahan was investigated .The best fitted problable distibution of pallutants concentration was determined and it was used for estimation of concentrations with different retarn periods. The gtimated pollutant concentration with different return periods is using Selected pdf. The results showed BOD5 and COD can be modeled by Gamma distribution , and TSS, No3, TP, Pb are statistically fitted with 2 lognormal distribution . Also , pollutant concentrations were increased with return period.