Research On Urban Stormwater Calculation Model And Method Based On Spatial Information Multi-Grid

With the accelerating of urbanization and the increasing of urban area, significant changes have taken place in the nature, culture and ecological system of the central city and surrounding areas, which will obviously affect the hydrological processes of the urban watershed. As a result, the urban rainstorm disaster becomes a growing threat which has caused great losses of traffic, electricity, production as well as people’s lives and properties. Urban stormwater model is an important means of describing the hydrological processes, analyzing the formation mechanism and assessing the losses of the urban rainstorm disasters, which can provide strong data supports for the urban drainage system planning and designing projects.In recent years, domestic and foreign scholars have proposed a series of urban stormwater models. In order to make these models more adaptable to the characteristics of particular urban watersheds, the hydrological principles and algorithms of them have been continuously improved. Although the calculation methods and theoretical systems of urban stormwater models are relatively mature at present, there are still some problems in the actual applications. For example, the partition approaches of calculation cells for rainfall-runoff simulation are unreasonable, and the spatial heterogeneous characteristics of the hydrological information in the urban watersheds are not considered in the parameter collection and estimation methods. Moreover, the stormwater logging calculation methods are lack of representation, which can not reflect the features of stormwater logging processes. In the region where the basic hydrological data is relatively scarce, it is very difficult to find an effective modeling method for the existing urban stormwater models.This paper focus on the multidisciplinary research which integrates the spatial information multi-grid technology with the urban stormwater model, and several urban stormwater calculation methods based on the urban stormwater multi-grid are proposed. In order to solve the problems in existing urban stormwater models, these methods make full use of the advantages of spatial information multi-grid in analyzing the hydrological information, integrating different data and improving the utilization of resources. The application results indicate that these methods can optimize the application effects of exsiting urban stormwater models and have better value of theory innovation and integrated innovation. The main research contents and innovations in this paper are as follows:(1) The proposing and constructing of the theme urban stormwater multi-grid oriented to urban stormwater calculation:according to the characteristics of rainfall-runoff processes in urban watersheds, the theme spatial information multi-grid oriented to the urban stormwater calculation, which called urban stromwater multi-grid, is proposed in this paper. Based on the theory framework and key contents of urban stormwater multi-grid, the constructing method, coding scheme, data model, storage structure of it are designed. Urban stormwater multi-grid achieves the multistage subdivision for urban watershed based on the multi-level rainfall-runoff processes, and resolves the defect of traditional calculation cell partition approaches in the existing urban stormwater models, which can provide strong supports to the information collection and model construction works.(2) Urban rainfall-runoff improved SWMM model and method based on stormwater multi-grid:considering the advantages of stormwater multi-grid in watershed features description and information utilization, this paper regards the stormwater multi-grid as the carrier of the multi-source, heterogeneous and hierarchical information in urban watershed, so as to deeply integrate it to the SWMM model and solve the problems of lagging data organization method, low utilization of data and unreasonable parameter collection and estimation standard in the traditional urban rainfall-runoff model represented by SWMM. And then the urban rainfall-runoff improved SWMM model based on stormwater multi-grid is proposed, which achieves the aim of distributed, graphic-attribute integration management and effective utilization for hydrological information.(3) Urban storm waterlogging "cone" calculation model and method based on stormwater multi-grid:according to the correlation between urban storm waterlogging and rainfall-runoff processes, and considering the close relation between the urban rainfall-runoff feature and stormwater multi-grid, a grid-based "cone" calculation model for urban storm waterlogging is proposed. The characteristics of urban storm waterlogging are fully reflected by integrating stormwater grid with the storm waterlogging calculation principle in this model. Based on the spatial information technology, this model solves the problems of poor adaptability, high data requirement and low operating efficiency in the traditional waterlogging algorithms, and provides high efficiency and low requirements simulation method for the urban storm waterlogging processes.(4) Case study and results analysis of stormwater multi-grid in urban stormwater calculation:urban stormwater multi-grid in this paper is applied to an urban watershed for case study under the condition of incomplete information. The hydrological parameters of study area are obtained by using3S technology and the spatial distribution of stormwater grid. On the basis of it, the rainfall-runoff and waterlogging model of study area are established. Through the analysis and comparison of the simulation results, it is fully demonstrated that the stormwater multi-grid can make the urban stormwater model more typical, reasonable and adaptable for urban watersheds.As a thematic application and further study of spatial information multi-grid in urban stormwater calculation research, stormwater multi-grid not only embodies the multidisciplinary idea between spatial information technology and hydrological modeling in urban watersheds, but also provides a new method to improve the existing urban stormwater models and make the results of them more valuable in the emergency decision and standard formulation processes of urban rainstorm disasters.