| With increasing concern for the deteriorating water quality of urban water bodies, planning for urban runoff control should simultaneously consider both quantity and quality management. This thesis presents a methodology for urban runoff quantity and/or quality control planning. The methodology provides a systematic framework for preliminary screening of urban runoff control systems and narrows the range of control alternatives for subsequent design level analysis. It consists of five steps: input rainfall/pollution analysis, assessment of existing runoff/pollution conditions, evaluation of existing control system performance, least-cost analysis of control systems, and sensitivity analysis. The quantity and quality of urban runoff is dependent upon rainfall and catchment and drainage system characteristics. Storm event analyses are conducted to determine the probability distribution and statistics of rainfall characteristics (event rainfall volume, duration, interevent time and annual number of rainfall events) of rainfall series. To model runoff quality, a constant concentration approach is proposed in which runoff pollution load is equal to the product of runoff volume and an expected pollutant concentration. Analytical probabilistic models are then derived to predict long-term average runoff volume and pollutant load controlled. The most promising combination of control measures for achieving a certain level of runoff controlled can be determined by optimizing different kinds of control measures and comparing the cost-effectiveness relationship among different combinations of control measures. Sensitivity analyses are then conducted to assess the impact of uncertainty in parameter estimation on the analysis results. A catchment in the Borough of East York, Toronto, is used to demonstrate the application of the methodology. |
