Layout Optimization Of Low Impact Development Facilities In New Development Zone

Urbanization has changed the conditions of the site of underlying surface, and has changed the natural state of hydrological mechanisms. As a consequence, it has caused some serious issues, such as the water environment deteriorating, increasing the pollution of runoff, the risk of waterlogging, and the losing of rainwater resources. Since the traditional drainage patterns cannot meet the needs of the current sustainable urban development, the Low Impact Development with core concept "source control, decentralized development" has showed its advantages. According to the requirements of China’s sponge city construction, a lot of low impact development facilities will be constructed.By learning from the advanced theory and practical experience and based on the features of new development zone, this study addressed the low impact development facilities layout optimization processes and scheme comparison systems.First, for the common LID facilities such as Bioswale, Rain Garden, Permeable Pavement, Ecological Roof, Gravel Retention System, Depressive Green Field and Wetland, The paper use typical diagram to design, standardize and generalize the structure of those facilities. Meanwhile, The paper compare and analyze every LID facility from the aspect of rainwater control mechanism, suitable conditions, the effect of construction and the costs of the investment.Then, The paper propose the LID facilities layout optimization processes and introduce the determination of rainwater control objectives, basic data analyses, LID facilities preliminary comparison, the SWMM model, scheme layout and comparison. We mainly focused on the parameter selection of SWMM model, sensitivity analysis and program layout adjustment principles.Based on our current domestic LID development environment, and combined expert scoring and analytic hierarchy process, we propose the core indicators of assessment program. After considering of the national emission reduction policies, the economic interests of investors and the public benefits, we built a scheme comparison model and made program to calculate, and this has made the foundation of selecting suitable LID schema.Finally, after using our research results to design and compare the LID system of the Beijing CITCI Complex and Guangzhou Education City project, it illustrates that the optimization system and comparison model is operable.By learning from the advanced theory and practical experience and based on the features of new development zone, this study addressed the low impact development facilities layout optimization processes and comparison model. So the findings have theoretical significance, and practical value to solve the urbanization processes in China rainwater management issues.