عنوان مقاله [English]
Pollution due to toxic elements in urban runoff of rainfall and entry them into surface water resources, causes severe environmental damages. Therefore, identification of theses pollutants and their statistical analysis is necessary to provide management guidelines. In this study, investigation of Ni and Zn data in the runoff events of Hamedan city was made by study and fitting of as many as forty-five continuous probability distributions. For this purpose, the sampling was conducted from the outlets of the city basin during seven precipitation events firstly. Fitting different distribution functions on event mean concentrations of Ni and Zn and instantaneous concentration series of Ni and Zn carried out by method of moments (MOM), moment of linear (MOL), maximum likelihood estimation (MLE) and least square error (LSE) secondly. For evaluation and ranking of the functions, were used the goodness of fit Kolmogorov–Smirnov and Anderson–Darling tests. The result showed that among of different distributions, the Wakeby is suitable function for frequency analysis of the event mean concentrations of Ni and Zn. In addition, The Johnson SB and Generalized extreme value distributions were identified as the suitable functions for fitting the instantaneous concentration series of Ni and Zn respectively.