Abstract
Urban storm inundation, which frequently has dramatic impacts on city safety and social life, is an emergent and difficult issue. Due to the complexity of urban surfaces and the variety of spatial modeling elements, the lack of detailed hydrological data and accurate urban surface models compromise the study and implementation of urban storm inundation simulations. This paper introduces a Constrained Delaunay Triangular Irregular Network (CD-TIN) to model fine urban surfaces (based on detailed ground sampling data) and subsequently employs a depression division method that refers to Fine Constrained Features (FCFs) to construct computational urban water depressions. Storm-runoff yield is placed through mass conservation to calculate the volume of rainfall, runoff and drainage. The water confluences between neighboring depressions are provided when the water level exceeds the outlet of a certain depression. Numerical solutions achieved through a dichotomy are introduced to obtain the water level. Therefore, the continuous inundation process can be divided into different time intervals to obtain a series of inundation scenarios. The main campus of Beijing Normal University (BNU) was used as a case study to simulate the “7.21” storm inundation event to validate the usability and suitability of the proposed methods. In comparing the simulation results with in-situ observations, the proposed method is accurate and effective, with significantly lower drainage data requirements being obtained. The proposed methods will also be useful for urban drainage design and city inundation emergency preparations.
Highlights
Urban areas serve as the center of populations, property and resources, and one severe storm flood can result in dramatic property damage and financial losses
The Constrained Delaunay Triangular Irregular Network (CD-Triangle Irregular Network (TIN)) is an appropriate method for representing the Fine Constrained Features (FCFs) on an urban surface in detail
The airborne LiDAR can capture the top surfaces of urban features properly, but some FCFs are often difficult to be distinguished, such as the street curbs, because they may be smaller than the resolution of the measuring instrument
Summary
Urban areas serve as the center of populations, property and resources, and one severe storm flood can result in dramatic property damage and financial losses. The time series of storm-runoff modeling results provide flexibility for modeling temporal inundation variations, avoiding the time consuming problem of most physically based flood models [25] These methods primarily rely on raster-based urban surfaces. This research introduces a new method for urban flood inundation simulation. It employs a CD-TIN to represent the fine urban surface, including all types of FCFs (e.g., water drain grates, street curbs, walls, and buildings). Urban water depression as the basic unit for flood inundation is generated and its related storm-runoff model, confluence algorithm between depressions are proposed to calculate the inundation depth.
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