References of "Erpicum, Sébastien"
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See detailApparent cohesion effects on overtopping-induced fluvial dike breaching
Rifai, Ismail; El Kadi Abderrezzak, Kamal; Hager, Willi et al

in Journal of Hydraulic Research (in press)

Flow overtopping can lead to the initiation of breaching and failure of fluvial dikes, causing severe inundations and damage in the protected areas. For flood risk management and prevention, the accurate ... [more ▼]

Flow overtopping can lead to the initiation of breaching and failure of fluvial dikes, causing severe inundations and damage in the protected areas. For flood risk management and prevention, the accurate estimate of flow discharge across the fluvial dike breach is paramount, requiring the precise understanding of the breach expansion. Laboratory experiments were conducted to analyse the effects of fine sand, inducing apparent cohesion in the dike material, on the breach development and outflow. Tests were conducted under controlled inflow discharge and dike material composed of either homogeneous non-cohesive coarse sand or heterogeneous fine sand/coarse sand mixtures. Based on the non-intrusive Laser Profilometry technique, high temporal and spatial resolution of the three-dimensional breach geometry evolution was measured, indicating a small effect of the fine material on the overall breach dynamics. A detailed analysis revealed, however, that fine sand induces less frequent slope collapses but larger sliding/failing lumps compared to homogenous non-cohesive coarse sand. [less ▲]

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See detailExperimental test bench for performance-assessment of large submersible and dry-action pumps used in waterways
Hardy, Joris ULiege; Erpicum, Sébastien ULiege; Pirotton, Michel ULiege et al

Conference (2021, April 13)

Pumping in waterways, particularly in artificial canals, is energy-intensive, costly and may be responsible for the emission of large quantities of CO2. Innovative pumping technologies have the potential ... [more ▼]

Pumping in waterways, particularly in artificial canals, is energy-intensive, costly and may be responsible for the emission of large quantities of CO2. Innovative pumping technologies have the potential to reduce energy consumption; but their performance needs to be thoroughly as-sessed. This communication presents the design, sizing and construction of an experimental test bench for evaluating the performance of large submersible and dry-action centrifugal pumps typically used in waterways. It enables testing prototype-scale pumps and was designed in close collaboration with stakeholders such as canal operators. This experimental facility is challeng-ing on many aspects given its size, as well as requirements for power supply and for measure-ment of system efficiency. [less ▲]

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See detailOccurrence and characteristic frequencies of nappe oscillations at free-overfall structures
Kitsikoudis, Vasileios ULiege; Lodomez, Maurine; Dewals, Benjamin ULiege et al

in Journal of Hydraulic Engineering (2021), 147(2),

The present study investigated the occurrence and characteristic frequency of nappe oscillations on weirs by re-analysing data from 52 experimental configurations. The considered configurations include ... [more ▼]

The present study investigated the occurrence and characteristic frequency of nappe oscillations on weirs by re-analysing data from 52 experimental configurations. The considered configurations include various shapes of the weir crest and a range of weir geometric and hydraulic characteristics with two different scales. Nappes were either confined with lateral and back walls forming a non-vented air pocket between the nappe and the weir or unconfined with atmospheric pressure everywhere around the nappe. Oscillations occurred at nappes with uniformly distributed approaching flow of low velocity and unit discharge between 0.01 and 0.06 m2/s, regardless of the model scale. Weir crests that favoured nappe oscillations had an upstream profile without geometric discontinuities. A dimensionless frequency of nappe oscillations was expressed as a power function of the ratio of fall height to the water depth at the point of detachment at the crest, separately for quarter-round and truncated half-round weir crests. The exponents of the two obtained power functions were very close to each other, which allows the usage of their average so that different weir crests exhibit solely offsetting curves. [less ▲]

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See detailPorosity Models for Large-Scale Urban Flood Modelling: a Review
Dewals, Benjamin ULiege; Bruwier, Martin ULiege; Pirotton, Michel ULiege et al

in Water (2021)

In the context of large-scale urban flood modelling, porosity shallow-water models enable a con-siderable speed-up in computations, while preserving information on subgrid topography. Over the last two ... [more ▼]

In the context of large-scale urban flood modelling, porosity shallow-water models enable a con-siderable speed-up in computations, while preserving information on subgrid topography. Over the last two decades, major improvements have been brought to these models; but a single gen-erally accepted model formulation has not yet been reached. Instead, existing models vary in many respects. Some studies define porosity parameters at the scale of the computational cells or cell interfaces, while others treat the urban area as a continuum and introduce statistical-ly-defined porosity parameters. The porosity parameters are considered either isotropic or aniso-tropic, and depth-independent or depth-dependent. The underlying flow models are based either on the full shallow-water equations, or on approximations thereof, with various parametrizations of flow resistance. Here, we provide a review of the spectrum of porosity models developed so far for large scale urban flood modelling. [less ▲]

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See detailAssessment of lumped physically-based numerical models of dyke breaching
Schmitz, Vincent ULiege; Wylock, Grégoire; El Kadi Abderrezzak, Kamal et al

in Geophysical Research Abstracts (2021)

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See detailFrom Labyrinth to Piano Key weirs: the story
Erpicum, Sébastien ULiege; Lempérière, François; Ouamane, Ahmed et al

in Hydrolink (2020), 4(2020), 126-127

Labyrinth weirs are an efficient solution for free surface flow whose development has been initially favored by a close collaboration between research and industry in the United States. Piano Key weirs ... [more ▼]

Labyrinth weirs are an efficient solution for free surface flow whose development has been initially favored by a close collaboration between research and industry in the United States. Piano Key weirs improve the traditional Labyrinth concept and have been developed with the same collaborative spirit at an international level. Both structures have a huge potential of development and application worldwide, which has been exploited yet only in a few countries. [less ▲]

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See detailModélisation hydraulique 2D pour la détermination des zones inondables
Archambeau, Pierre ULiege; Erpicum, Sébastien ULiege; Dewals, Benjamin ULiege et al

Scientific conference (2020, November 09)

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See detailAge of Water Particles as a Diagnosis of Steady-state Flows in Shallow Rectangular Reservoirs
Dewals, Benjamin ULiege; Archambeau, Pierre ULiege; Bruwier, Martin ULiege et al

in Water (2020), (12), 2819

The age of a water particle in a shallow man-made reservoir is defined as the time elapsed since it entered it. Analyzing this diagnostic timescale provides valuable information for optimally sizing and ... [more ▼]

The age of a water particle in a shallow man-made reservoir is defined as the time elapsed since it entered it. Analyzing this diagnostic timescale provides valuable information for optimally sizing and operating such structures. Here, the constituent-oriented age and residence time theory (CART) is used to obtain not only the mean age, but also the water age distribution function at each location. The method is applied to 10 different shallow reservoirs of simple geometry (rectangular), in a steady-state framework. The results show that complex, multimodal water age distributions are found, implying that focusing solely on simple statistics (e.g., mean or median age) fails to reflect the complexity of the actual distribution of water age. The latter relates to the fast or slow pathways that water particles may take for traveling from the inlet to the outlet of the reservoirs. [less ▲]

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See detailInfluence of model formulation on the critical morphological acceleration factor: an analytical study
Dewals, Benjamin ULiege; Archambeau, Pierre ULiege; Pirotton, Michel ULiege et al

E-print/Working paper (2020)

The morphological acceleration factor (Morfac) has been used for over two decades to speed-up long term morphodynamic simulations. However, the Morfac values are usually set heuristically and hardly any ... [more ▼]

The morphological acceleration factor (Morfac) has been used for over two decades to speed-up long term morphodynamic simulations. However, the Morfac values are usually set heuristically and hardly any study investigated theoretically the critical Morfac value leading to a predefined level of accuracy. In this research, we evaluated theoretically the critical Morfac value from the analysis of the amplitude and phase errors induced by the use of Morfac. While the few existing studies focused only on relatively low Froude numbers and a single mathematical formulation of the morphodynamic model, we consider here a significantly wider range of Froude numbers, including supercritical flow, and we compare four different model formulations. We show that the model formulation leading to the highest critical Morfac values for subcritical flow is not the same as for supercritical flow. [less ▲]

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See detailA combined experimental and numerical strategy to assess the influence of model geometric distortion in laboratory scale modelling of urban flooding
Li, Xuefang ULiege; Erpicum, Sébastien ULiege; Mignot, Emmanuel et al

Conference (2020, July)

Accurate modelling of urban flood hazard remains hampered by a lack of suitable validation data. In contrast with water marks and inundation extent, discharge partition in-between streets and flow fields ... [more ▼]

Accurate modelling of urban flood hazard remains hampered by a lack of suitable validation data. In contrast with water marks and inundation extent, discharge partition in-between streets and flow fields are generally unknown, while they have a strong influence on flood risk (human destabilization, scour, contaminant transport). Laboratory experiments may provide a valuable complement to field data to achieve robust validation of flood hazard models. However, urban flooding is a multiscale phenomenon, with horizontal length scales (~ 103 m) are considerably larger than the vertical ones (~ 1 m). Therefore, recent experimental studies of urban flooding used geometrically distorted scale models, with a vertical scale factor smaller than the horizontal one. Though, little is known so far on the bias induced by model geometric distortion in the case of urban flooding. To address this issue, we have combined computational modelling with laboratory experiments. Based on 100+ numerical simulations, the bias induced by model geometric distortion on flow depth and discharge partition was found of the order of 10 %, which is not negligible compared to other uncertainties involved in urban flood hazard modelling. Moreover, when the geometric distortion is varied, the induced bias shows an intriguing non-monotonous evolution, which we could relate to a competition between frictional and secondary head losses. New tailored laboratory experiments are on-going on a “series” of laboratory scale models, i.e. several laboratory models representing the same urban layout at various scales. The outcomes of these experiments will make more robust the conclusions drawn from computational modelling. [less ▲]

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See detailNumerical insights into the effects of model geometric distortion in laboratory experiments of urban flooding
Li, Xuefang ULiege; Erpicum, Sébastien ULiege; Mignot, Emmanuel et al

in Water Resources Research (2020)

Geometrically distorted scale models have been a valuable tool for physical modelling of urban flooding in a network of streets. However, little is known so far about the bias induced in such cases by the ... [more ▼]

Geometrically distorted scale models have been a valuable tool for physical modelling of urban flooding in a network of streets. However, little is known so far about the bias induced in such cases by the model geometric distortion. Here, we use 2D computational modelling to provide a first systematic quantification of this bias in the case of a synthetic urban layout. The bias is found to be generally small, with the maximum deviations of the upscaled flow depth and discharge partition from the corresponding values of the undistorted model being around 10 % in the case of relatively rapid and shallow flow conditions. When the geometric distortion is increased, the computations reveal a non-monotonous pattern of the flow variables (depth, discharge partition, size of flow separation zones), which results from a competition between declining frictional losses and growing local losses in the model. These findings may guide the design of distorted scale models of urban flooding and assist the interpretation of laboratory observations for assessing flood protection measures, for process understanding or for validating computational modelling. [less ▲]

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See detailProcedural generation of flood-sensitive urban layouts
Mustafa, Ahmed Mohamed El Saeid ULiege; Zhang, Xiao Wei; Aliaga et al

in Environment and Planning B: Urban Analytics and City Science (2020), 47(5), 889-911

Aside from modeling geometric shape, three-dimensional (3D) urban procedural modeling has shown its value in understanding, predicting and/or controlling effects of shape on design and urban planning. In ... [more ▼]

Aside from modeling geometric shape, three-dimensional (3D) urban procedural modeling has shown its value in understanding, predicting and/or controlling effects of shape on design and urban planning. In this paper, instead of the construction of flood resistant measures, we create a procedural generation system for designing urban layouts that passively reduce water depth during a flooding scenario. Our tool enables exploring designs that passively lower flood depth everywhere or mostly in chosen key areas. Our approach tightly integrates a hydraulic model and a parameterized urban generation system with an optimization engine so as to find the least cost modification to an initial urban layout design. Further, due to the computational cost of a fluid simulation, we train neural networks to assist with accelerating the design process. We have applied our system to several real-world locations and have obtained improved 3D urban models in just a few seconds. [less ▲]

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See detailUnderground pumped-storage hydropower (UPSH) at the Martelange mine (Belgium): interactions with groundwater flow
Pujades, Estanislao; Orban, Philippe ULiege; Archambeau, Pierre ULiege et al

in Energies (2020), 13

Underground pumped-storage hydropower (UPSH) is a promising technology to manage the electricity production in flat regions. UPSH plants consist of an underground and surface reservoirs. The energy is ... [more ▼]

Underground pumped-storage hydropower (UPSH) is a promising technology to manage the electricity production in flat regions. UPSH plants consist of an underground and surface reservoirs. The energy is stored by pumping water from the underground to the surface reservoir and is produced by discharging water from the surface to the underground reservoir. The underground reservoir can be drilled, but a more efficient alternative, considered here, consists in using an abandoned mine. Given that mines are rarely waterproofed, there are concerns about the consequences (on the efficiency and the environment) of water exchanges between the underground reservoir and the surrounding medium. This work investigates numerically such water exchanges and their consequences. Numerical models are based on a real abandoned mine located in Belgium (Martelange slate mine) that is considered as a potential site to construct an UPSH plant. The model integrates the geometrical complexity of the mine, adopts an operation scenario based on actual electricity prices, simulates the behavior of the system during one year and considers two realistic scenarios of initial conditions with the underground reservoir being either completely full or totally drained. The results show that (1) water exchanges may have important consequences in terms of efficiency and environmental impacts, (2) the influence of the initial conditions is only relevant during early times, and (3), an important factor controlling the water exchanges and their consequences may be the relative location of the natural piezometric head with respect the underground reservoir. [less ▲]

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See detailDiscussion of "modeling and Prototype Testing of Flows over Flip-Bucket Aerators" by Penghua Teng and James Yang
Erpicum, Sébastien ULiege; Dewals, Benjamin ULiege; Archambeau, Pierre ULiege et al

in Journal of Hydraulic Engineering (2020), 146(5),

The Authors propose an interesting comparison between physical scale modeling, CFD modeling and field observations related to a unique spillway with flip buckets and built-in aerators. Despite the field ... [more ▼]

The Authors propose an interesting comparison between physical scale modeling, CFD modeling and field observations related to a unique spillway with flip buckets and built-in aerators. Despite the field observations are mainly qualitative, the Discussers would like to thank the Authors for sharing with the scientific community these results. Indeed, such analysis are very valuable but are too rare. Physical models and CFD are both modeling tools. They both suffer limitations and, consequently, their results need to be carefully and objectively discussed and validated. Comparison to quantitative prototype data is the only way to proof the validity of a modeling technique for real projects. However, such validation data remain sparse and rare, in particular considering large hydraulic structures. In the following, the Discussers aim to raise one issue in the Authors’ research and to highlight recent contributions and existing datasets, which are of direct relevance for the interpretation and discussion of the Authors’ results. [less ▲]

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See detailInfluence of urban forms on surface flow in urban pluvial flooding
Bruwier, Martin ULiege; Maravat, Claire; Mustafa, Ahmed et al

in Journal of Hydrology (2020), 582

This paper presents a systematic analysis of the influence of nine urban characteristics (distance be-tween buildings, mean building size, building coverage, etc.) on surface flow in case of pluvial ... [more ▼]

This paper presents a systematic analysis of the influence of nine urban characteristics (distance be-tween buildings, mean building size, building coverage, etc.) on surface flow in case of pluvial flooding. Time dependent stored volumes, outflow discharges and mean water depths were comput-ed for a set of 2,000 synthetic urban forms, considering various terrain slopes and return periods of the rainfall. An efficient porosity-based surface flow model was used to compute the 2D flow varia-bles. Statistical analysis of the relationship between the flow and urban variables highlights that the flooding severity is mostly influenced by the building coverage. [less ▲]

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See detailHydraulic structures engineering: An evolving science in a changing world
Erpicum, Sébastien ULiege; Crookston, Brian; Bombardelli, Fabian et al

in WIREs Water (2020)

Hydraulic structures are critical for water management. Yet many structures continue to be neglected, in poor condition, and inadequate in adapting to evolving societal challenges associated with shifting ... [more ▼]

Hydraulic structures are critical for water management. Yet many structures continue to be neglected, in poor condition, and inadequate in adapting to evolving societal challenges associated with shifting climatic events and population growth. In this context, hydraulic structures engineering should be moving from traditional design considerations towards sustainability, i.e. continuing to meet current and future social, environmental, and economic needs. This requires this community to embrace and help advance global and multidisciplinary perspectives. Therefore, this paper presents the authors’ point of view on current trends, concerns and needs related to hydraulic structures engineering. Furthermore, the authors propose a new, forward-looking framework for the consideration of the hydraulic structures community that is grounded on the evolution of inter-connected research tools and methodologies in addition to emphasizing and bolstering strong links between academia and industry. The evolution of this framework has naturally originated from the pervasive challenge of validating the design and operation of hydraulic structures in the field for frequent and extreme conditions. The authors suggest that future developments of hydraulic structures engineering require (1) continuous updating of complementary tools and methodologies following technological developments, (2) addressing the lack of detailed field observations, (3) increasing interactions of hydraulic specialists with other scientific disciplines and water experts, and (4) restoring a strong collaboration between academia and industry. It is anticipated that in this way the hydraulic structures community, and all of society, will make a new step towards more sustainable and resilient interactions with nature and between communities in water management. [less ▲]

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See detailContinuous monitoring of fluvial dike breaching by a Laser Profilometry Technique
Rifai, Ismail; Schmitz, Vincent ULiege; Erpicum, Sébastien ULiege et al

in Water Resources Research (2020), 56

A non-intrusive, high resolution Laser Profilometry Technique (LPT) has been developed for continuous monitoring of the three dimensional (3D) evolving breach in laboratory models of non-cohesive fluvial ... [more ▼]

A non-intrusive, high resolution Laser Profilometry Technique (LPT) has been developed for continuous monitoring of the three dimensional (3D) evolving breach in laboratory models of non-cohesive fluvial dikes. This simple and low cost setup consists of a commercial digital video camera and a sweeping red diode 30 mW laser projecting a sheet over the dike. The 2D image coordinates of each deformed laser profile incident on the dike are transformed into 3D object coordinates using the Direct Linear Transformation algorithm. All 3D object coordinates computed over a laser sweeping cycle are merged to generate a cloud of points describing the instantaneous surface. The DLT-based image processing algorithm uses control points and reference axes, so that no prior knowledge is needed on the position, orientation and intrinsic characteristics of the camera, nor on the laser position. Because the dike is partially submerged, ad hoc refraction correction has been developed. Algorithms and instructions for the implementation of the LPT are provided. Reconstructions of a dike geometry with the LPT and with a commercial laser scanner are compared in dry conditions. Using rigid dike geometries, the repeatability of the measurements, the refraction correction, and the dike reconstruction have been evaluated for submerged conditions. Two laboratory studies of evolving fluvial dike breaching due to flow overtopping have been conducted to demonstrate the LPT capabilities and accuracy. The LPT has advantages in terms of flexibility and spatiotemporal resolution, but high turbidity and water surface waves may lead to inaccurate geometry reconstructions. [less ▲]

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See detailDiscrepancies in flood modelling approaches in transboundary river systems: legacy of the past or well-grounded choices?
Kitsikoudis, Vasileios ULiege; Becker, Bernhard; Huismans, Ymkje et al

in Water Resources Management (2020), 34

Flood modelling in transnational rivers requires efficient cross-border collaboration among the riparian countries. Currently, each country/region usually uses a different hydraulic modelling approach ... [more ▼]

Flood modelling in transnational rivers requires efficient cross-border collaboration among the riparian countries. Currently, each country/region usually uses a different hydraulic modelling approach, which may hinder the modelling of the entire river. For the sake of accurate and consistent river modelling there is a necessity for the establishment of a framework that fosters international collaborations. This study investigates the current hydraulic modelling approach across the whole length of the River Meuse, the main course of which crosses three North-western European countries. The numerical models used by French, Belgian, and Dutch agencies and authorities were interconnected by exchanging boundary conditions at the borders. At the central part of the river, the Belgian hydraulic model assumed steady flow conditions, while the rest of the river was modelled in unsteady mode. Results for various flood scenarios revealed a distinctive pattern of water depths at the Belgian-Dutch border. To clarify whether this is a bias induced by the change in modelling approach at the border (steady vs. unsteady), we remodelled a stretch of the river across the Belgian-Dutch border using a consistent unsteady modelling approach. The steady and unsteady approaches led to similar patterns across the border, hence discarding the hypothesis of a bias resulting from a change in the employed model. Instead, the pattern in water depths was attributed to a change in the topography of the Meuse Valley, where there is a transition from a narrow steep corridor with limited water storing capacity in Ardennes massif to wide floodplains in the Dutch lowlands. The associated flood damping for the 100-year discharge is less than 1 % in the Ardennes and exceeds 15 % in the Dutch lowlands. It can be inferred that the current differences in regional hydraulic modelling approaches for the River Meuse are generally well-grounded and not just a legacy of the past. [less ▲]

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