Integrated urban stormwater management modeling

Recent years have witnessed a growing interest in stormwater management planning. As a result, new methods and techniques have been constantly developed and older techniques have been evaluated and updated. However, to address a variety of issues of concern in an increasingly complex urban environment, traditional approaches to stormwater management planning with a singular focus on runoff quantity control have proven to be insufficient, and a new paradigm or framework for stormwater management is required emphasizing integrated modeling approaches in the development of state-of-the-art modeling tools.; The major objective of the present research is to develop integrated probabilistic models, with which the existing drainage systems can be operated and yet-to-be-built systems can be designed to achieve both required levels of quantity and quality control. The integrated model consists of a number of functional components, such as rainfall-runoff transformations, pollutant buildup, washoff, storage/treatment, etc. The development of each component is guided by a number of methodological considerations. For example, the rainfall-runoff transformation employed in the model actually conceptualizes major runoff generation mechanisms, based on which system performance measures, such as average annual volume of spills, runoff quantity capture efficiency, the fraction of pollutant removed in the storage facilities as well as long term pollutant load to receiving waters can be developed and evaluated. As the key element in the development of probabilistic models, six different types of the rainfall-runoff transformations based on various hydrologic considerations are formulated in the models. The formulation of a disaggregated form of pollutant buildup function, in contrast to the aggregated form is intended to elaborate pollutant buildup and washoff processes. With two different types of pollutant buildup functions and various options in choosing rainfall-runoff transformations, the integrated probabilistic models have great flexibility to address a number of “what if” rainfall-runoff scenarios, and serve as planning tools for exploring and evaluating a wide range of alternative system design.