Comparative Analysis of Building Representations in TELEMAC-2D for Flood Inundation in Idealized Urban Districts

Li Li,Yan Yan,Mei Mei,Liu Liu,Shao Shao,Wang Wang

doi:10.3390/w11091840

Abstract

This study aims to better understand the impact of different building representations and mesh resolutions on urban flood simulations using the TELEMAC-2D model in idealized urban districts. A series of numerical models based on previous laboratory experiments was established to simulate urban flooding around buildings, wherein different building layouts (aligned and staggered) were modeled for different building representations: building–hole (BH), building–block (BB), and building–resistance (BR) methods. A sensitivity analysis of the Manning coefficient for building grids indicated that the unit-width discharge and water depth in building grids reduce as the Manning coefficient is less than 104 m-1/3⋅s. The simulated depths via the BH, BB, and BR methods were compared with the measured data in terms of three accuracy indicators: root mean square error, Pearson product–moment correlation coefficient, and Nash–Sutcliffe efficiency. Observing apparent discrepancies based on the hydrographs was difficult; however, some slight distinctions were observed based on the aforementioned three indicators. The sensitivity of 1, 2, and 5 cm mesh resolutions was also analyzed: results obtained using 1 cm resolution were better than those obtained using other resolutions. The complex flow regime around buildings was also investigated based on mesh resolution, velocity, and Froude number according to our results. This study provides key data regarding urban flood model benchmarks, focusing on the effect of different building representations and mesh resolutions.

Highlights

As the global climate has been changing, the number and intensity of natural disasters have significantly increased in recent decades [1,2]
Results indicate that the TELEMAC-2D model can accurately simulate flood flow in this case
Urban buildings significantly impact urban flooding, in terms of water depth, which is a crucial parameter for flood risk management and damage assessment

Summary

Introduction

As the global climate has been changing, the number and intensity of natural disasters have significantly increased in recent decades [1,2]. Owing to the frequent occurrence of urban floods caused by heavy rain, urban floods have become an important question and research interest has increased in this field [3]. Cities are widely impacted and heavily damaged by floods because of their vulnerability and sensitivity, in rapidly developing urban areas. Beijing suffered significant damage from a heavy rainstorm in 2012, the losses for which exceeded 1.86 billion USD; more than. 1.6 million people were impacted by the resulting flood [4]. Existing research on flood risk has focused on flood modeling, which indicates a lack of field investigation. This is because: Water 2019, 11, 1840; doi:10.3390/w11091840 www.mdpi.com/journal/water

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