scholarly journals Methodology for qualitative urban flooding risk assessment

2013 ◽  
Vol 68 (4) ◽  
pp. 829-838 ◽  
Author(s):  
João P. Leitão ◽  
Maria do Céu Almeida ◽  
Nuno E. Simões ◽  
André Martins
Keyword(s):  
Risk Assessment ◽  
Public Transportation ◽  
Flood Risk ◽  
Urban Areas ◽  
Overland Flow ◽  
Urban Flood ◽  
Rainfall Events ◽  
Transportation Services ◽  
Recent Developments ◽  
Flooding Risk

Pluvial or surface flooding can cause significant damage and disruption as it often affects highly urbanised areas. Therefore it is essential to accurately identify consequences and assess the risks associated with such phenomena. The aim of this study is to present the results and investigate the applicability of a qualitative flood risk assessment methodology in urban areas. This methodology benefits from recent developments in urban flood modelling, such as the dual-drainage modelling concept, namely one-dimensional automatic overland flow network delineation tools (e.g. AOFD) and 1D/1D models incorporating both surface and sewer drainage systems. To assess flood risk, the consequences can be estimated using hydraulic model results, such as water velocities and water depth results; the likelihood was estimated based on the return period of historical rainfall events. To test the methodology two rainfall events with return periods of 350 and 2 years observed in Alcântara (Lisbon, Portugal) were used and three consequence dimensions were considered: affected public transportation services, affected properties and pedestrian safety. The most affected areas in terms of flooding were easily identified; the presented methodology was shown to be easy to implement and effective to assess flooding risk in urban areas, despite the common difficulties in obtaining data.

Bi-directional Coupling of an Unstructured Triangular Meshes-based Integrated Hydrodynamic Model for Heterogeneous Feature-based Urban Flood Simulation

2021 ◽  
Author(s):  
Guoqiang Peng ◽  
Zhuo Zhang ◽  
Tian Zhang ◽  
Zhiyao Song ◽  
Arif Masrur
Keyword(s):  
Water Flow ◽  
Urban Areas ◽  
Overland Flow ◽  
Coupled Model ◽  
Flood Simulation ◽  
Urban Flood ◽  
Essential Condition ◽  
Flow Processes ◽  
Feature Based ◽  
Heterogeneous Feature

Abstract Urban pluvial flash floods have become a matter of widespread concern, as they severely impact people’s lives in urban areas. Hydrological and hydraulic models have been widely used for urban flood management and urban planning. Traditionally, to reduce the complexity of urban flood modelling and simulations, simplification or generalization methods have been used; for example, some models focus on the simulation of overland water flow, and some models focus on the simulation of the water flow in sewer systems. However, the water flow of urban floods includes both overland flow and sewer system flow. The overland flow processes are impacted by many different geographical features in what is an extremely spatially heterogeneous environment. Therefore, this article is based on two widely used models (SWMM and ANUGA) that are coupled to develop a bi-directional method of simulating water flow processes in urban areas. The open source overland flow model uses the unstructured triangular as the spatial discretization scheme. The unstructured triangular-based hydraulic model can be better used to capture the spatial heterogeneity of the urban surfaces. So, the unstructured triangular-based model is an essential condition for heterogeneous feature-based urban flood simulation. The experiments indicate that the proposed coupled model in this article can accurately depict surface waterlogged areas and that the heterogeneous feature-based urban flood model can be used to determine different types of urban flow processes.

scholarly journals Enhanced DEM-based flow path delineation methods for urban flood modelling

2012 ◽  
Vol 15 (2) ◽  
pp. 568-579
Author(s):  
J. P. Leitão ◽  
D. Prodanović ◽  
S. Boonya-aroonnet ◽  
Č. Maksimović
Keyword(s):  
Urban Areas ◽  
Overland Flow ◽  
Flow Path ◽  
Flow Paths ◽  
Urban Flood ◽  
Bouncing Ball ◽  
Digital Elevation ◽  
Synthetic Test ◽  
Water Accumulation ◽  
Flooding Events

In order to simulate surface runoff and flooding, one-dimensional (1D) overland flow networks can be automatically delineated using digital elevation models (DEM). The resulting network comprises flow paths and terrain depressions/ponds and is essential to reliably model pluvial (surface) flooding events in urban areas by so-called 1D/1D models. Conventional automatic DEM-based flow path delineation methods have problems in producing realistic overland flow paths when detailed high-resolution DEMs of urban areas are used. The aim of this paper is to present the results of research and development of three enhanced DEM-based overland flow path delineation methods; these methods are triggered when the conventional flow path delineation process stops due to a flow obstacle. Two of the methods, the ‘bouncing ball and buildings’ and ‘bouncing ball and A*’ methods, are based on the conventional ‘bouncing ball’ concept; the third proposed method, the ‘sliding ball’ method, is based on the physical water accumulation concept. These enhanced methods were tested and their results were compared with results obtained using two conventional flow path delineation methods using a semi-synthetic test DEM. The results showed significant improvements in terms of the reliability of the delineated overland flow paths when using these enhanced methods.

Application of risk based approach to flood risk assessment in urban areas

2012 ◽  
Author(s):  
T Rashidul Kabir ◽  
B Gersonius ◽  
C Zevenbergen ◽  
P van Gelder ◽  
Mohammad Shah
Keyword(s):  
Risk Assessment ◽  
Flood Risk ◽  
Urban Areas ◽  
Flood Risk Assessment

A methodology for linking 2D overland flow models with the sewer network model SWMM 5.1 based on dynamic link libraries

2016 ◽  
Vol 73 (12) ◽  
pp. 3017-3026 ◽  
Author(s):  
Jorge Leandro ◽  
Ricardo Martins
Keyword(s):  
Network Model ◽  
Urban Areas ◽  
Overland Flow ◽  
Coupled Model ◽  
Dynamic Link Library ◽  
Urban Flood ◽  
Flow Models ◽  
Sewer Network ◽  
Dynamic Link

Abstract Pluvial flooding in urban areas is characterized by a gradually varying inundation process caused by surcharge of the sewer manholes. Therefore urban flood models need to simulate the interaction between the sewer network and the overland flow in order to accurately predict the flood inundation extents. In this work we present a methodology for linking 2D overland flow models with the storm sewer model SWMM 5. SWMM 5 is a well-known free open-source code originally developed in 1971. The latest major release saw its structure re-written in C ++ allowing it to be compiled as a command line executable or through a series of calls made to function inside a dynamic link library (DLL). The methodology developed herein is written inside the same DLL in C + +, and is able to simulate the bi-directional interaction between both models during simulation. Validation is done in a real case study with an existing urban flood coupled model. The novelty herein is that the new methodology can be added to SWMM without the need for editing SWMM's original code. Furthermore, it is directly applicable to other coupled overland flow models aiming to use SWMM 5 as the sewer network model.

Flood analysis in mixed-urban areas reflecting interactions with the complete water cycle through coupled hydrologic-hydraulic modelling

2010 ◽  
Vol 62 (6) ◽  
pp. 1386-1392 ◽  
Author(s):  
N. D. Sto. Domingo ◽  
A. Refsgaard ◽  
O. Mark ◽  
B. Paludan
Keyword(s):  
Urban Areas ◽  
Overland Flow ◽  
Computer Modelling ◽  
Water Cycle ◽  
New Method ◽  
Urban Flood ◽  
Flood Modelling ◽  
Essential Components ◽  
Flood Analysis ◽  
Urban Flood Modelling

The potential devastating effects of urban flooding have given high importance to thorough understanding and management of water movement within catchments, and computer modelling tools have found widespread use for this purpose. The state-of-the-art in urban flood modelling is the use of a coupled 1D pipe and 2D overland flow model to simultaneously represent pipe and surface flows. This method has been found to be accurate for highly paved areas, but inappropriate when land hydrology is important. The objectives of this study are to introduce a new urban flood modelling procedure that is able to reflect system interactions with hydrology, verify that the new procedure operates well, and underline the importance of considering the complete water cycle in urban flood analysis. A physically-based and distributed hydrological model was linked to a drainage network model for urban flood analysis, and the essential components and concepts used were described in this study. The procedure was then applied to a catchment previously modelled with the traditional 1D-2D procedure to determine if the new method performs similarly well. Then, results from applying the new method in a mixed-urban area were analyzed to determine how important hydrologic contributions are to flooding in the area.

scholarly journals Risk Assessment of Urban Floods Based on a SWMM-MIKE21-Coupled Model Using GF-2 Data

2021 ◽  
Vol 13 (21) ◽  
pp. 4381
Author(s):  
Lidong Zhao ◽  
Ting Zhang ◽  
Jun Fu ◽  
Jianzhu Li ◽  
Zhengxiong Cao ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Return Period ◽  
Flood Risk ◽  
Global Climate ◽  
Total Loss ◽  
Return Periods ◽  
Rapid Urbanization ◽  
Urban Floods ◽  
Urban Flood ◽  
Inundation Depth

Global climate change and rapid urbanization have caused increases in urban floods. Urban flood risk assessment is a vital method for preventing and controlling such disasters. This paper takes the central region of Cangzhou city in Hebei Province as an example. Detailed topographical information, such as the buildings and roads in the study area, was extracted from GF-2 data. By coupling the two models, the SWMM and MIKE21, the spatial distribution of the inundation region, and the water depth in the study area under different return periods, were simulated in detail. The results showed that, for the different return periods, the inundation region was generally consistent. However, there was a large increase in the mean inundation depth within a 10-to-30-year return period, and the increase in the maximum inundation depth and inundation area remained steady. The comprehensive runoff coefficient in all of the scenarios exceeded 0.8, indicating that the drainage system in the study area is insufficient and has a higher flood risk. The flood risk of the study area was evaluated based on the damage curve, which was obtained from field investigations. The results demonstrate that the loss per unit area was less than CNY 250/m2 in each return period in the majority of the damaged areas. Additionally, the total loss was mainly influenced by the damaged area, but, in commercial areas, the total loss was highly sensitive to the inundation depth.

scholarly journals Vulnerability Assessment of Urban Floods in Lahore, Pakistan using GIS based integrated Analytical Hierarchy Approach

2021 ◽  
Vol 58 (1) ◽  
pp. 85-96
Author(s):  
Sahar Zia ◽  
Safdar A. Shirazi ◽  
Muhammad Nasar-u-Minallah
Keyword(s):  
Land Use ◽  
Flood Risk ◽  
Urban Areas ◽  
Physical Factors ◽  
Urban Flooding ◽  
Residential Areas ◽  
Urban Flood ◽  
Risk Areas ◽  
Practical Tool ◽  
Flood Risk Mapping

Urban flooding is getting attention due to its adverse impact on urban lives in mega cities of the developing world particularly Pakistan. This study aims at finding a suitable methodology for mapping urban flooded areas to estimate urban flooding vulnerability risks in the cities of developing countries particularly Lahore, Pakistan. To detect the urban flooded vulnerability and risk areas due to natural disaster, GIS-based integrated Analytical Hierarchy Process (AHP) is applied for the case of Lahore, which is the second most populous city and capital of the Punjab, Pakistan. For the present research, the flood risk mapping is prepared by considering these significant physical factors like elevation, slope, and distribution of rainfall, land use, density of the drainage network, and soil type. Results show that the land use factor is the most significant to detect vulnerable areas near roads and commercial areas. For instance, this method of detection is 88%, 80% and 70% accurate for roads, commercial and residential areas. The methodology implemented in the present research can provide a practical tool and techniques to relevant policy and decision-makers authorities to prioritize and actions to mitigate flood risk and vulnerabilities and identify certain vulnerable urban areas, while formulating a methodology for future urban flood risk and vulnerability mitigation through an objectively simple and organizationally secure approach. 

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