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Article ; Online: Laboratory Investigation Into the Effect of the Storage Capacity of a City Block on Unsteady Urban Flood Flows

Mejía‐Morales, Miguel Angel / Mignot, Emmanuel / Paquier, André / Proust, Sébastien

Water Resources Research. 2023 Apr., v. 59, no. 4 p.e2022WR032984-

2023

Abstract: The increasing occurrence of urban flooding in recent years demands a more accurate flood hazard assessment. Therefore, a better understanding of the predominant hydraulic processes in urban flood flows is required. The present paper reports an ... ...

Abstract	The increasing occurrence of urban flooding in recent years demands a more accurate flood hazard assessment. Therefore, a better understanding of the predominant hydraulic processes in urban flood flows is required. The present paper reports an experimental study conducted in a laboratory scale model, which represents an urban area consisting of a rectangular city block and four surrounding streets. The objective is to quantify the impact of open areas within the city block on the key features of floodwaters. Tests are carried out under unsteady flow conditions, by using three inflow hydrographs with different unsteadiness levels. For each inflow hydrograph, the space available for floodwater volume storage within the block (storage capacity, ϕ) is varied, keeping the boundary conditions unchanged. A case where the city block has no space for floodwater storage (i.e., ϕ = 0) is used as a reference case. The results indicate that the unsteadiness level of the inflow hydrograph, especially during the rising stage, has a strong influence on the floodwater volume stored within the city block. The increase in storage capacity within the city block leads to a reduction of the global peak outflow discharge, a decrease in flow depths and a local increase in velocities in some streets and within the city block. Finally, with these variations in floodwater features, the level of risk to pedestrians is also impacted, increasing locally when the storage capacity of the block increases.
Keywords	hazard characterization ; hydrograph ; models ; research ; risk ; transient flow ; urban areas ; water
Language	English
Dates of publication	2023-04
Publishing place	John Wiley & Sons, Ltd
Document type	Article ; Online
Note	JOURNAL ARTICLE
ZDB-ID	5564-5
ISSN	1944-7973 ; 0043-1397
ISSN (online)	1944-7973
ISSN	0043-1397
DOI	10.1029/2022WR032984
Database	NAL-Catalogue (AGRICOLA)

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Article ; Online: Flow structure in compound open-channel flows in the presence of transverse currents

Proust Sébastien / Nikora Vladimir

E3S Web of Conferences, Vol 40, p

2018 Volume 05024

Abstract: The structure of free-surface flows is experimentally investigated in a laboratory flume with a compound cross-section consisting of a central main channel (MC) and two adjacent floodplains (FPs). The study focuses on the effects of transverse currents ... ...

Abstract	The structure of free-surface flows is experimentally investigated in a laboratory flume with a compound cross-section consisting of a central main channel (MC) and two adjacent floodplains (FPs). The study focuses on the effects of transverse currents on: (i) mixing layers and quasi-two-dimensional coherent structures at the interfaces between MC and FPs; (ii) secondary currents developing across the channel; and (iii) large and very-large-scale motions that were recently observed in non-compound open channel flows. Transverse currents represent spanwise depth- and time-averaged flow from MC to FPs or vice versa. The study is based on one-point and two-point ADV measurements. Streamwise non-uniform flows are generated by imposing an imbalance in the discharge distribution between MC and FPs at the flume entrance, keeping the total flow rate the same for all scenarios. It is shown that even small transverse currents can be very effective in flow modification, as they can significantly displace the mixing layer, shear-layer turbulence, and coherent structures towards MC or FP, depending on the current direction. They can also alter the distribution and strength of the secondary currents. The interactions of quasi-two-dimensional coherent structures, very-large-scale motions, and secondary currents at different conditions are also part of this study.
Keywords	Environmental sciences ; GE1-350
Subject code	532
Language	English
Publishing date	2018-01-01T00:00:00Z
Publisher	EDP Sciences
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Experimental flows through an array of emerged or slightly submerged square cylinders over a rough bed.

Oukacine, Marina / Proust, Sébastien / Larrarte, Frédérique / Goutal, Nicole

Scientific data

2021 Volume 8, Issue 1, Page(s) 6

Abstract: The experimental dataset presented was collected in an 18 m long and 1 m wide laboratory flume. Low to high flood flows through an urbanized floodplain were modelled. The floodplain bed is rough, modelled with dense artificial grass. A square cylinder ... ...

Abstract	The experimental dataset presented was collected in an 18 m long and 1 m wide laboratory flume. Low to high flood flows through an urbanized floodplain were modelled. The floodplain bed is rough, modelled with dense artificial grass. A square cylinder array, representing house models, was set on the rough bed. The cylinder immersion rate was varied: cylinders are emerged for three flow cases and slightly submerged for one case. The experimental dataset comprises water levels, measured using an ultrasonic transit time probe, velocities across the channel measured using an Acoustic Doppler Velocimetry with a side looking probe, and velocities in longitudinal-vertical planes measured using Particle Image Velocimetry. These data could help understanding the physical processes associated with high flood flows through urbanized floodplains, with a focus on the transition from emerged to submerged obstacles. They could also be used as benchmark data to assess the ability of numerical models from one to three-dimensions to estimate the flood hazard (water depth, velocity) over a wide range of flood event magnitudes.
Language	English
Publishing date	2021-01-11
Publishing country	England
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	2775191-0
ISSN	2052-4463 ; 2052-4463
ISSN (online)	2052-4463
ISSN	2052-4463
DOI	10.1038/s41597-020-00791-w
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: Can the 2D shallow water equations model flow intrusion into buildings during urban floods?

Dewals, Benjamin / Kitsikoudis, Vasileios / Angel Mejía-Morales, Miguel / Archambeau, Pierre / Mignot, Emmanuel / Proust, Sébastien / Erpicum, Sébastien / Pirotton, Michel / Paquier, André

Journal of Hydrology. 2023 Apr., v. 619 p.129231-

2023

Abstract: The multiple flow paths existing in urban environments lead to complex flow fields during urban flooding. Modelling these flow processes with three-dimensional numerical models may be scientifically sound; however, such numerical models are ... ...

Abstract	The multiple flow paths existing in urban environments lead to complex flow fields during urban flooding. Modelling these flow processes with three-dimensional numerical models may be scientifically sound; however, such numerical models are computationally demanding. To ascertain whether urban floods can be modelled with faster tools, this study investigated for the first time the capacity of the 2D shallow water equations (SWE) in modelling the flow patterns within and around urban blocks with openings, i.e., involving flow exchanges between the flows in the streets and within the urban blocks (e.g., through alleys leading to courtyards or through broken windows or doors). Laboratory experiments of idealized urban floods were simulated with two academic 2D SWE models, with their most notable difference being the parameterization of the eddy viscosity. Specifically, the first model had a turbulence closure based on flow depth and friction velocity while the second model had a depth-averaged k-ε turbulence closure. Thirteen urban layouts were considered with steady flow and five with unsteady flow. Both models simulated the flow depths accurately for the steady cases. The discharge distribution in the streets and the flow velocities were predicted with lower accuracy, particularly in layouts with large open spaces. The average deviation of the modelled discharge distribution at the outlets was 2.5% and 7.3% for the first and second model, respectively. For the unsteady cases, only the first model was tested. It predicted well the velocity pattern during the falling limb of a flood wave, while it did not reproduce all recirculation zones in the rising limb. The peak flow depths in the streets and the peak discharges at the outlets were predicted with an average deviation of 6.7% and 8.6%, respectively. Even though some aspects of the flow in an urban setup are 3D, the findings of this study support the modelling of such processes with 2D SWE models.
Keywords	friction velocity ; models ; steady flow ; transient flow ; turbulent flow ; viscosity ; Experimental hydraulics ; Numerical modelling ; Open channel flow ; Shallow water equations ; Turbulence ; Urban flood
Language	English
Dates of publication	2023-04
Publishing place	Elsevier B.V.
Document type	Article ; Online
Note	Pre-press version
ZDB-ID	1473173-3
ISSN	1879-2707 ; 0022-1694
ISSN (online)	1879-2707
ISSN	0022-1694
DOI	10.1016/j.jhydrol.2023.129231
Database	NAL-Catalogue (AGRICOLA)

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Article: Impact of the porosity of an urban block on the flood risk assessment: A laboratory experiment

Mejía-Morales, Miguel Angel / Mignot, Emmanuel / Paquier, André / Sigaud, Darius / Proust, Sébastien

Journal of hydrology. 2021 Nov., v. 602

2021

Abstract: Physical modelling of urban flooding usually considers that the flow is concentrated in the streets, assuming that urban blocks and individual buildings are non-porous structures. This assumption is open to criticism, as potential lateral flow exchanges ... ...

Abstract	Physical modelling of urban flooding usually considers that the flow is concentrated in the streets, assuming that urban blocks and individual buildings are non-porous structures. This assumption is open to criticism, as potential lateral flow exchanges through openings in the walls of an urban block (e.g. gates, windows and doors) are likely to modify the flow pattern in the block and adjacent streets. This paper reports an experimental study conducted on a 5.4 m long and 3.2 m wide physical model, representing a rectangular urban block and four surrounding streets. The focus of the study was on investigating the lateral flow exchange processes between the porous urban block and its adjacent streets during flooding, for a variable urban block porosity. Eight porosity values were studied, keeping the same boundary conditions. A porosity equals zero, i.e. a flow around a non-porous block, served as a reference flow situation. For each porosity value, the impact of the lateral flow exchanges on the spatial distribution of flow depth and velocity in the streets and within the block was assessed, as well as the risk to pedestrians. First, it was found that, in the streets surrounding the block, flow depth and depth-averaged velocity can vary by 12% and 70%, respectively, when modifying block porosity. Within the block, the most impacted flow parameter is the number and size of horizontal secondary flow cells. Second, noticeable differences in flow depth can be observed from either side of an opening between street and block. Third, when moving away from the block, flow parameters are little affected. Last, the risk to pedestrians, which is both related to local flow depth and velocity, is dependent on the block porosity value.
Keywords	laboratory experimentation ; models ; porosity ; risk ; risk assessment
Language	English
Dates of publication	2021-11
Publishing place	Elsevier B.V.
Document type	Article
ZDB-ID	1473173-3
ISSN	1879-2707 ; 0022-1694
ISSN (online)	1879-2707
ISSN	0022-1694
DOI	10.1016/j.jhydrol.2021.126715
Database	NAL-Catalogue (AGRICOLA)

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Article ; Online: Depth-averaged velocity and bed shear stress in unsteady open channel flow over rough bed

Khuntia Jnana Ranjan / Devi Kamalini / Proust Sebastien / Khatua Kishanjit Kumar

E3S Web of Conferences, Vol 40, p

2018 Volume 05071

Abstract: Very few studies have been carried out in the past in estimating depth-averaged velocity and bed shear stress in unsteady flow over rough beds. An experiment is thus conducted to investigate the vertical and lateral velocity profiles under unsteady flow ... ...

Abstract	Very few studies have been carried out in the past in estimating depth-averaged velocity and bed shear stress in unsteady flow over rough beds. An experiment is thus conducted to investigate the vertical and lateral velocity profiles under unsteady flow conditions in a rough open channel for various flow depths. One hydrogram is repeatedly passed through the rectangular flume with a fixed rigid grass bed. Using micro Pitot tube and Acoustic Doppler Velocimeter (ADV), the flow patterns are investigated at both lateral and longitudinal positions over different cross-sections. For two typical flow depths, the velocities in both the rising limb and falling limb are observed. Hysteresis effect between stage-discharge (h ~ Q) rating curve between rising and falling limbs is illustrated. Lateral distribution of depth-averaged velocity and bed shear stress are plotted at three different cross sections and compared with the steady flow conditions. In falling limb of an unsteady flow case, both depth-averaged velocity and bed shear stress distribution in the central region is higher than that of steady flow case. However, in the rising limb, the bed shear stress of unsteady flow is less than that of steady flow case. Further, in an unsteady flow, the magnitude of depth-averaged velocity is found to increase towards the downstream sections. Along the downstream positions, bed shear stress values increase for lower flow depths and decrease for higher flow depth cases.
Keywords	Environmental sciences ; GE1-350
Subject code	532 ; 551
Language	English
Publishing date	2018-01-01T00:00:00Z
Publisher	EDP Sciences
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Flow distribution in diverging compound channels using improved independent subsection method

Das Bhabani Shankar / Devi Kamalini / Proust Sebastien / Khatua Kishanjit Kumar

E3S Web of Conferences, Vol 40, p

2018 Volume 05068

Abstract: Experiments have been conducted in three diverging compound channels for different flow conditions to study the flow distribution in floodplain, upper and lower main channel. In a compound channel, vertical apparent shear exists on the interface between ... ...

Abstract	Experiments have been conducted in three diverging compound channels for different flow conditions to study the flow distribution in floodplain, upper and lower main channel. In a compound channel, vertical apparent shear exists on the interface between the upper main channel and the floodplain, which generally accelerates the flow on the floodplain and resists the flow in the upper main channel. In addition, a horizontal apparent shear stress also occurs on the interface between the upper and lower main channels, which generally accelerates the flow in the lower one and resists the flow in the upper one. Therefore, it is essential to consider the exchanges of momentum at both vertical and horizontal shear layer regions. In this paper, an attempt is made to improve the classical independent subsection method (ISM) to determine the magnitudes of flow and velocities in both upper and lower main channels. Four subsections are created in improved ISM according to the vertical and horizontal division lines that correspond to the vertical interface between the main channel and floodplain and the horizontal interface between upper and lower main channels respectively. The improved ISM consists in a set of four coupled 1D momentum equations (instead three equations of classical ISM) for subsections and a mass conservation equation for the total cross-section. The computed results show that the method is well capable of predicting the discharge distributions in the floodplain and main channel (both at upper and lower main channel).
Keywords	Environmental sciences ; GE1-350
Subject code	003
Language	English
Publishing date	2018-01-01T00:00:00Z
Publisher	EDP Sciences
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article: Effect of climate change over landfalling hurricanes at the Yucatan Peninsula

Appendini, Christian M / Meza-Padilla, Rafael / Abud-Russell, Said / Proust, Sébastien / Barrios, Roberto E / Secaira-Fajardo, Fernando

Climatic change. 2019 Dec., v. 157, no. 3-4

2019

Abstract: Tropical cyclones generated in the North Atlantic and the Eastern Pacific are a constant hazard for Mexico. Along with a possible increased hazard of tropical cyclones due to global warming, there is an inescapable increase in vulnerability and disaster ... ...

Abstract	Tropical cyclones generated in the North Atlantic and the Eastern Pacific are a constant hazard for Mexico. Along with a possible increased hazard of tropical cyclones due to global warming, there is an inescapable increase in vulnerability and disaster risk towards tropical cyclones due to population growth and coastal infrastructure developments. In Mexico, the Yucatan Peninsula has the highest landfall rates of major category hurricanes in addition to the highest rate of population growth in major tourist cities. Therefore, the assessment of landfalling tropical cyclones is of paramount importance for emergency management and planning. This paper provides an assessment of the future climate for landfalling tropical cyclones in the Yucatan Peninsula, based on synthetic tropical cyclones driven by atmospheric models (reanalysis and six different general circulation models (GCMs)) and under the Representative Concentration Pathway 8.5 climate change scenario. The results using the ensemble mean from the GCMs show that the Yucatan Peninsula will be more susceptible to more frequent intense hurricanes and more regular events undergoing rapid intensification. We conclude that even under the uncertainty imposed by the results, it is more likely than not that the future climate will bring more extreme events to this area. Therefore, it becomes imperative to implement strategic planning based on the characterization of tropical cyclone hazards framed within the assessment of global warming effects.
Keywords	climate ; hurricanes ; infrastructure ; population growth ; risk ; tourists ; uncertainty ; Mexico
Language	English
Dates of publication	2019-12
Size	p. 469-482.
Publishing place	Springer Netherlands
Document type	Article
Note	NAL-AP-2-clean
ZDB-ID	751086-x
ISSN	0165-0009
ISSN	0165-0009
DOI	10.1007/s10584-019-02569-5
Database	NAL-Catalogue (AGRICOLA)

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Article ; Online: Gérer des inondations par des ouvrages dispersés sur le bassin versant

POULARD, Christine / ROYET, Paul / LEBLOIS, Étienne / FAURE, Jean-Baptiste / BREIL, Pascal / PROUST, Sébastien

Sciences, Eaux & Territoires, Vol 2017, Iss 23, Pp 34-

principes et méthodes de diagnostic d'efficacité probabiliste

2017 Volume 41

Abstract: La gestion intégrée des inondations à l’échelle du bassin versant offre des perspectives intéressantes pour poser un diagnostic pertinent et trouver des solutions de gestion de l’aléa, notamment à l’amont des enjeux. Cet article s'intéresse ici aux ... ...

Abstract	La gestion intégrée des inondations à l’échelle du bassin versant offre des perspectives intéressantes pour poser un diagnostic pertinent et trouver des solutions de gestion de l’aléa, notamment à l’amont des enjeux. Cet article s'intéresse ici aux différentes étapes de l'estimation de l'aléa inondation et nous présente les principes et méthodes de diagnostic d'efficacité probabiliste pour améliorer la gestion des inondations par des ouvrages de prévention dispersés sur le bassin versant.
Keywords	Inondation ; Risque ; Bassin versant ; Ouvrages ; Méthodes ; Diagnostic ; Environmental technology. Sanitary engineering ; TD1-1066 ; Environmental sciences ; GE1-350
Language	French
Publishing date	2017-05-01T00:00:00Z
Publisher	Institut national de recherche pour l’agriculture, l’alimentation et l’environnement (INRAE)
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article: Nonuniform flow in compound channel: A 1‐D method for assessing water level and discharge distribution

Proust, Sebastien / Bousmar, Didier / Riviere, Nicolas / Paquier, Andre / Zech, Yves

Water resources research. 2009 Dec., v. 45, no. 12

2009

Abstract: This paper investigates 1‐D modeling of nonuniform flows in compound channels. The issue is how to accurately predict both flow depth and mean velocity in the floodplain. A new model, called “Independent Subsections Method” (ISM), is presented here. ... ...

Abstract	This paper investigates 1‐D modeling of nonuniform flows in compound channels. The issue is how to accurately predict both flow depth and mean velocity in the floodplain. A new model, called “Independent Subsections Method” (ISM), is presented here. Unlike classical 1‐D models that solve a dynamic equation on the total cross section, the ISM estimates the water surface profile within each subsection. This enables the water level and the subsection mean velocities to be simultaneously calculated, without priority to any variable. In opposition to the Divided Channel Method (DCM), corrected DCM or the Exchange Discharge Model, the ISM assumes independent evolution of the discharge in each subsection of the compound channel. Indeed, this method does not assume equal head loss gradients in all subsections, and it does not impose the downstream discharge distribution. The ISM consists in a set of three coupled 1‐D momentum equations (written within main channel, left‐hand, and right‐hand floodplains) and a mass conservation equation on the total cross section. Mass and momentum exchanges at the interfaces between subsections are explicitly accounted for. This method is validated against experimental data for developing flows in straight compound channel, flows in skewed compound channel, flows in a symmetric converging or diverging compound channel, and flows in an asymmetrical compound channel with an abrupt floodplain contraction. For the 46 runs, the ISM predicts flow depth and mean velocity in the floodplain with a maximum relative error of 8% and 19%, respectively. The ISM also appears to be a useful theoretical tool to improve our understanding of physical processes governing compound channel flows.
Keywords	water flow ; hydrologic models ; velocity ; floodplains ; estimation ; model validation
Language	English
Dates of publication	2009-12
Size	p. W12411 (16 p.).
Document type	Article
ZDB-ID	5564-5
ISSN	0043-1397
ISSN	0043-1397
Database	NAL-Catalogue (AGRICOLA)

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