Abstract
Flood modelling can provide useful information to support flood risk assessment and management. The accuracy of flood simulation results is highly dependent on the quality of input data. In particular, digital elevation models (DEMs) may directly influence the performance of flood predictions and improper representation of complex urban features including buildings and bridges may lead to incorrect prediction of flooding paths and extents, and consequently miscalculate flood risk. In this work, a geographic information system (GIS)-based correction method is proposed to make modifications in high-resolution DEMs by adding building complexes and removing unphysical representations of bridges for a more realistic description of flood paths in considering the flow connectivity in intensely urbanized areas and with the objective of obtaining more accurate flood simulation results. The proposed DEM correction method is applied to support large-scale urban flood modelling in Fuzhou City, China, using an established hydrodynamic flood model known as High-Performance Integrated hydrodynamic Modelling System (HiPIMS). Comparisons are made to the simulation results with and without the DEM improvements using the proposed correction method. The results demonstrate that correct representation of the artificial structures in the urban DEM can significantly improve the flood simulation results.
Highlights
The risk of urban flooding is expected to rise in the twenty-first century and beyond due to rapid urbanization and increasing frequency of extreme precipitation events as a result of climate change (Milly et al 2002; Nirupama and Simonovic 2007; SemadeniDavies et al 2008; Hanson et al 2011; Fadhel et al 2018; Zhou et al 2019; Ziegler 2012)
As the urban area is characterized by densely distributed buildings, the raw digital elevation models (DEMs) including the zoom-in view in Fig. 5a cannot reflect well the reality
A geographic information system (GIS)-based DEM correction method for applications in large-scale urbanized areas is proposed in this work to improve city DEMs by better representing complex urban terrain features for more accurate hydrodynamic simulation of urban flooding
Summary
The risk of urban flooding is expected to rise in the twenty-first century and beyond due to rapid urbanization and increasing frequency of extreme precipitation events as a result of climate change (Milly et al 2002; Nirupama and Simonovic 2007; SemadeniDavies et al 2008; Hanson et al 2011; Fadhel et al 2018; Zhou et al 2019; Ziegler 2012). Many severe urban flood events have been reported across the world in the last two decades, for example, Hull, UK in July 2007, New York City, US in October 2012, Beijing, China in July 2012, Uttarakhand, India in July, 2013, Western Japan in July 2018, Northern Queensland, Australia in February 2019 and Zhengzhou, China in July, 2021. These urban floods have caused severe economic losses and even fatalities (Blake et al 2013; Coulthard and Frostick 2010; Zhang et al 2015). Following rapid advancement of computing technology and availability of high-resolution data, hydrodynamic models are capable of performing high-resolution flood predictions to provide temporal and spatial characteristics of flood inundation even in the highly complex urban environments (Ernst et al 2010; Yin et al 2016b)
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