| In recent decades, research in analytical probabilistic models used to analyze urban drainage systems has been expanding its scope to address both stormwater quantity and quality issues. As nonpoint source pollution continues to threaten stormwater quality, there is a pressing need for more effective analysis models. One such useful tool is analytical probabilistic modeling, whereby PDFs of rainfall characteristics are used as model inputs. Employing empirical buildup and washoff processes and a rainfall-runoff transformation that differentiate runoff contributions between pervious and impervious areas, the cumulative probability distributions for washoff load are obtained. Relatively close agreement is found between the observed field data and the analytically derived distribution of washoff load for nine commonly found pollutants. This modeling technique can be a viable option to continuous simulation modeling because of its substantially lesser computational effort at the screening and planning level of analyzing urban stormwater systems. |
