Integrated Methodology for Urban Flood Risk Mapping at the Microscale in Ungauged Regions: A Case Study of Hurghada, Egypt

Karim I Abdrabo,Dina Elleithy,Mohamed Saber,Omar M Habiba,Bahaa Elboshy,Tetsuya Sumi,Sameh A Kantoush

doi:10.3390/rs12213548

Karim I Abdrabo, Dina Elleithy + Show 5 more

Open Access

https://doi.org/10.3390/rs12213548

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Abstract

Flood risk mapping forms the basis for disaster risk management and the associated decision-making systems. The effectiveness of this process is highly dependent on the quality of the input data of both hazard and vulnerability maps and the method utilized. On the one hand, for higher-quality hazard maps, the use of 2D models is generally suggested. However, in ungauged regions, such usage becomes a difficult task, especially at the microscale. On the other hand, vulnerability mapping at the microscale suffers limitations as a result of the failure to consider vulnerability components, the low spatial resolution of the input data, and the omission of urban planning aspects that have crucial impacts on the resulting quality. This paper aims to enhance the quality of both hazard and vulnerability maps at the urban microscale in ungauged regions. The proposed methodology integrates remote sensing data and high-quality city strategic plans (CSPs) using geographic information systems (GISs), a 2D rainfall-runoff-inundation (RRI) simulation model, and multicriteria decision-making analysis (MCDA, i.e., the analytic hierarchy process (AHP)). This method was implemented in Hurghada, Egypt, which from 1996 to 2019 was prone to several urban flood events. Current and future physical, social, and economic vulnerability maps were produced based on seven indicators (land use, building height, building conditions, building materials, total population, population density, and land value). The total vulnerability maps were combined with the hazard maps based on the Kron equation for three different return periods (REPs) 50, 10, and 5 years to create the corresponding flood risk maps. In general, this integrated methodology proved to be an economical tool to overcome the scarcity of data, to fill the gap between urban planning and flood risk management (FRM), and to produce comprehensive and high-quality flood risk maps that aid decision-making systems.

Highlights

Over recent decades, urban flood risk has significantly increased in Egypt due to extensive urbanization and climate change (Table A1 in the Appendix A)
This study aims to (1) enhance the quality of hazard and vulnerability mapping at the urban microscale in ungauged regions and (2) to produce flood risk maps to support decision-makers in (A) determining the impact of urban development planned for 2027 on the existing urban area in Hurghada, (B) evaluating the 2027 city strategic plans (CSPs) from a flood risk perspective, and (C) prioritizing intervention points
The model was capable of simultaneously predicting the distributed runoff and flood inundation depths considering infiltration parameters that enhance the quality of the hazard maps produced

Summary

Introduction

Urban flood risk has significantly increased in Egypt due to extensive urbanization and climate change (Table A1 in the Appendix A). Various drivers have pushed urban extensions across large lowland areas prone to flood risk associated with the absence of both flood risk management (FRM) and effective spatial planning [2,3,4]. Detailed urban flood risk maps are required to propose efficient mitigation measures for existing urban areas and future expansions that will assist in better decision-making [9]. In this regard, flood risk mapping is expected to boost the efficiency of disaster management, reduce the devastating social and economic impacts of floods, and direct urban growth to safe areas [10]

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