Analysis of Pollution due to Ni and Zn in Urban Runoff Using by Probability Distribution Functions (Case Study: Hamedan)

Urban storm water has often been known as a major source of pollution influencing the surface water quality in urban areas (Fu et al., 2009). The urban storm water and its economic, social and environmental adverse effects can be predicted and controlled like other natural phenomena to minimize both the induced damages and partial rehabilitation of that for water demand. If first flush happens during the precipitation, in order to prevent the pollution entering to the vital resource, control of the initial part of runoff is sufficient. In this situation, a large amount of the equipment and costs of pollution control will diminish. The prediction of an event occurrence in the future depends on the accurate analysis of the relevant variable in the past. Because the runoff quality data is random and dependent on spatial and temporal variables, the analysis of such information requires using the statistical calculations. One of the most used statistical methods based on the probability is the frequency of the occurrence or the number of times that a given parameter takes place in a specified time interval. Ni and Zn are two elements of the heavy metal group with harmful effects in unallowable concentration on human health. In Hamedan, the urban storm water, alongside the route and after getting out of the catchment outlet, has been used to irrigate the agricultural crops and vegetables. The runoff enters the surface water and penetrates to the groundwater resources. Moreover, the high ability of Ni and Zn absorption in some agricultural plants and vegetables adversely influences the humans and animals. Therefore, the evaluation of the concentrations of these two elements is so necessary.