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.

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.

Linking of 2D and Pipe hydraulic models at fine spatial scales

2007 ◽  
Vol 2 (2) ◽  
Author(s):  
R.S. Carr ◽  
G.P. Smith
Keyword(s):  
Overland Flow ◽  
Spatial Scales ◽  
Urban Environments ◽  
Flow Paths ◽  
Urban Flood ◽  
Hydraulic Models ◽  
Small Complex ◽  
Modelling Techniques ◽  
Flood Risk Mapping ◽  
Fine Resolution

Linking of two-dimensional overland flow hydraulic models with one-dimensional storm water pipe models at very fine resolution is becoming a standard approach for urban flood investigations. This paper describes the application of such an approach to a variety of small, complex urbanised catchments in Australia and New Zealand. A benefit of this approach is that previously hidden information in terms of secondary flow paths and cross-flows become apparent, an outcome that is not possible with traditional 1D modelling tools. Generation of flood risk mapping is much simpler through the use of direct GIS interfaces to the model result files, making the modelling and presentation process much more transparent. The paper will describe the application of the models, the calibration approach and some specialised modelling techniques when working at such fine spatial resolution in urban environments.

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 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.

Urban Flood Inundation Model for High Density Building Area

2012 ◽  
Vol 7 (5) ◽  
pp. 554-559 ◽  
Author(s):  
Mohammad Farid ◽  
◽  
Akira Mano ◽  
Keiko Udo ◽  
Keyword(s):  
Urban Areas ◽  
Flow Model ◽  
Overland Flow ◽  
Channel Model ◽  
Momentum Equation ◽  
Capital City ◽  
Flood Inundation ◽  
Urban Flood ◽  
Overland Flow Model ◽  
Inundation Model

In this paper, the development of a flood inundation model considering the effect of buildings in dense urban areas is purposed. A 2D overland flow model is coupled with a 1D channel model to simulate flood inundation with an exchange of flow between rivers and surface floodplains. The momentum equation in the overland flow model is modified in order to consider urban flood characteristics. The “sharing rate,” which is defined as the occupancy area of building in each grid of a model domain, is applied to represent the effect of a building Drag force that occurs due to the reaction of force acting on a building is included. Hydrological processes are accommodated by combining a tank model in outsource terms. The model is applied to the downstream part of the Ciliwung River basin where Jakarta, the capital city of Indonesia, is located. Results regarding the water level and inundation map are compared with observed data and show fair agreement.

scholarly journals A versatile, linear complexity algorithm for flow routing in topographies with depressions

2019 ◽  
Vol 7 (2) ◽  
pp. 549-562 ◽  
Author(s):  
Guillaume Cordonnier ◽  
Benoît Bovy ◽  
Jean Braun
Keyword(s):  
Linear Time ◽  
Digital Elevation Models ◽  
Flow Path ◽  
Sequential Algorithm ◽  
Drainage Basins ◽  
Flow Routing ◽  
Flow Paths ◽  
Generic Structure ◽  
Digital Elevation ◽  
The Common

Abstract. We present a new algorithm for solving the common problem of flow trapped in closed depressions within digital elevation models, as encountered in many applications relying on flow routing. Unlike other approaches (e.g., the Priority-Flood depression filling algorithm), this solution is based on the explicit computation of the flow paths both within and across the depressions through the construction of a graph connecting together all adjacent drainage basins. Although this represents many operations, a linear time complexity can be reached for the whole computation, making it very efficient. Compared to the most optimized solutions proposed so far, we show that this algorithm of flow path enforcement yields the best performance when used in landscape evolution models. In addition to its efficiency, our proposed method also has the advantage of letting the user choose among different strategies of flow path enforcement within the depressions (i.e., filling vs. carving). Furthermore, the computed graph of basins is a generic structure that has the potential to be reused for solving other problems as well, such as the simulation of erosion. This sequential algorithm may be helpful for those who need to, e.g., process digital elevation models of moderate size on single computers or run batches of simulations as part of an inference study.

scholarly journals Modelling Infiltration Process, Overland Flow and Sewer System Interactions for Urban Flood Mitigation

Water ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2028
Author(s):  
Carlos Martínez ◽  
Zoran Vojinovic ◽  
Roland Price ◽  
Arlex Sanchez
Keyword(s):  
Urban Areas ◽  
Overland Flow ◽  
Surface Flow ◽  
Rainfall Runoff ◽  
Coupled Models ◽  
Infiltration Process ◽  
Urban Flood ◽  
Practical Applications ◽  
Urban Catchments ◽  
2D Model

Rainfall-runoff transformation on urban catchments involves physical processes governing runoff production in urban areas (e.g., interception, evaporation, depression, infiltration). Some previous 1D/2D coupled models do not include these processes. Adequate representation of rainfall–runoff–infiltration within a dual drainage model is still needed for practical applications. In this paper we propose a new modelling setup which includes the rainfall–runoff–infiltration process on overland flow and its interaction with a sewer network. We first investigated the performance of an outflow hydrograph generator in a 2D model domain. The effect of infiltration losses on the overland flow was evaluated through an infiltration algorithm added in a so-called Surf-2D model. Then, the surface flow from a surcharge sewer was also investigated by coupling the Surf-2D model with the SWMM 5.1 (Storm Water Management Model). An evaluation of two approaches for representing urban floods was carried out based on two 1D/2D model interactions. Two test cases were implemented to validate the model. In general, similar results in terms of peak discharge, water depths and infiltration losses against other 1D/2D models were observed. The results from two 1D/2D model interactions show significant differences in terms of flood extent, maximum flood depths and inundation volume.

scholarly journals Assessing the quality of digital elevation models obtained from mini unmanned aerial vehicles for overland flow modelling in urban areas

2016 ◽  
Vol 20 (4) ◽  
pp. 1637-1653 ◽  
Author(s):  
João P. Leitão ◽  
Matthew Moy de Vitry ◽  
Andreas Scheidegger ◽  
Jörg Rieckermann
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Urban Areas ◽  
Overland Flow ◽  
Weather Conditions ◽  
Flight Altitude ◽  
Flow Modelling ◽  
Aerial Vehicles ◽  
Digital Elevation ◽  
Flight Parameters

Abstract. Precise and detailed digital elevation models (DEMs) are essential to accurately predict overland flow in urban areas. Unfortunately, traditional sources of DEM, such as airplane light detection and ranging (lidar) DEMs and point and contour maps, remain a bottleneck for detailed and reliable overland flow models, because the resulting DEMs are too coarse to provide DEMs of sufficient detail to inform urban overland flows. Interestingly, technological developments of unmanned aerial vehicles (UAVs) suggest that they have matured enough to be a competitive alternative to satellites or airplanes. However, this has not been tested so far. In this study we therefore evaluated whether DEMs generated from UAV imagery are suitable for urban drainage overland flow modelling. Specifically, 14 UAV flights were conducted to assess the influence of four different flight parameters on the quality of generated DEMs: (i) flight altitude, (ii) image overlapping, (iii) camera pitch, and (iv) weather conditions. In addition, we compared the best-quality UAV DEM to a conventional lidar-based DEM. To evaluate both the quality of the UAV DEMs and the comparison to lidar-based DEMs, we performed regression analysis on several qualitative and quantitative metrics, such as elevation accuracy, quality of object representation (e.g. buildings, walls and trees) in the DEM, which were specifically tailored to assess overland flow modelling performance, using the flight parameters as explanatory variables. Our results suggested that, first, as expected, flight altitude influenced the DEM quality most, where lower flights produce better DEMs; in a similar fashion, overcast weather conditions are preferable, but weather conditions and other factors influence DEM quality much less. Second, we found that for urban overland flow modelling, the UAV DEMs performed competitively in comparison to a traditional lidar-based DEM. An important advantage of using UAVs to generate DEMs in urban areas is their flexibility that enables more frequent, local, and affordable elevation data updates, allowing, for example, to capture different tree foliage conditions.

scholarly journals A Versatile, Linear Complexity Algorithm for Flow Routing in Topographies with Depressions

2018 ◽  
Author(s):  
Guillaume Cordonnier ◽  
Benoît Bovy ◽  
Jean Braun
Keyword(s):  
Linear Time ◽  
Digital Elevation Models ◽  
Flow Path ◽  
Sequential Algorithm ◽  
Drainage Basins ◽  
Flow Routing ◽  
Flow Paths ◽  
Generic Structure ◽  
Digital Elevation ◽  
The Common

Abstract. We present a new algorithm for solving the common problem of flow trapped in closed depressions within digital elevation models, as encountered in many applications relying on flow routing. Unlike other approaches (e.g., the so-called Priority-Flood depression filling algorithm), this solution is based on the explicit computation of the flow paths both within and across the depressions through the construction of a graph connecting together all adjacent drainage basins. Although this represents many operations, a linear time-complexity can be reached for the whole computation, making it very efficient. Compared to the most optimized solutions proposed so far, we show that this algorithm of flow path enforcement yields the best performance when used in landscape evolution models. Besides its efficiency, our proposed method has also the advantage of letting the user choose among different strategies of flow path enforcement within the depressions (i.e., filling vs. carving). Furthermore, the computed graph of basins is a generic structure that has the potential to be reused for solving other problems as well. This sequential algorithm may be helpful for those who need to, e.g., process digital elevation models of moderate size on single computers or run batches of simulations as part of an inference study.

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