Semi-explicit modelling of watersheds with urban drainage systems

in Engineering Applications of Computational Fluid Mechanics (2012), 6(1), 46-57

A trade-off methodology has been developed to account for impervious surfaces and drainage effects accurately, without the need for modelling the entire drainage network in detail. Undrained impervious ... [more ▼]

A trade-off methodology has been developed to account for impervious surfaces and drainage effects accurately, without the need for modelling the entire drainage network in detail. Undrained impervious areas have been distinguished from drained ones. Rain falling on the former has been discharged as overland flow, whereas flow on the later has been routed separately using “virtual pipes”, which enable a simplified process-oriented modelling of the drainage network. [less ▲]

On the advantage of using risk curves to assess flood protection measures

in Mambretti, Stefano (Ed.) Environmental Risk (2012)

Modern flood management approaches require the quantification of flood risk, accounting for the hazard component (flood frequency and inundation intensity) as well as the vulnerability of the floodplains ... [more ▼]

Modern flood management approaches require the quantification of flood risk, accounting for the hazard component (flood frequency and inundation intensity) as well as the vulnerability of the floodplains (exposure, value and susceptibility). In this chapter, we present a detailed flood risk model, in which flow computation, monetary valuation of the assets and damage calculation are conducted at the scale of individual buildings or facilities. To avoid the shortcoming of focusing on economic damage, psycho-social impacts of floods are also included in the analysis. The model has been applied to evaluate three flood protection measures on a river reach in the Meuse basin (Belgium). The resulting risk curves show that such a micro-scale risk analysis provides important insights into the relative influence of the different flood protection measures. This could neither be evaluated through a more standard hydraulic analysis nor through the quantification of flood risk by only a single number. [less ▲]

Dike-break induced flows: a simplified model

Conference (2011, November)

A simplified model for the prediction of the steady-state outflow through a breach in an inland dike is presented. It consists in the application of the mass and momentum conservation principles to a ... [more ▼]

A simplified model for the prediction of the steady-state outflow through a breach in an inland dike is presented. It consists in the application of the mass and momentum conservation principles to a macroscopic control volume. A proper definition of the shape of the control volume enables to take into account the main characteristics of the flow and thus to compensate for the extreme simplification of the space discretisation of the model. At the breach, a relation derived from the shallow-water equations is used to determine the directions of the flow. Developments have been guided by numerical simulations and results have been compared to experimental data. Both the precision and the application domain of the simplified model are found satisfactory. [less ▲]

Hydromorphological restauration of Alpine rivers

Conference (2011, November)

Flood risk analysis in the Meuse river basin

in Urban Flood Risk Management (2011, September 21)

The goal of the study presented in the paper consists in understanding the vulnerability of economic systems to a modification of the hydrology due to climate change in the Meuse river basin. The latter ... [more ▼]

The goal of the study presented in the paper consists in understanding the vulnerability of economic systems to a modification of the hydrology due to climate change in the Meuse river basin. The latter extends over several regions in four different countries. A transnational approach is thus necessary to keep consistency throughout the international catchment. In this paper, we begin by illustrating how a strong collaboration between scientists and water authorities of the different parts of the basin has lead to a consistent approach for conducting flood risk analysis. Hazard modeling was conducted to get flood maps in the whole basin, considering various climate scenarios. In Wallonia, accurate hydraulic simulations were performed with the fully dynamic flow model WOLF2D entirely developed at the University of Liege (Erpicum et al., 2010). The outcomes of this inundation modeling constitute suitable inputs for the subsequent exposure analysis. The latter has been performed at a meso-scale using land use maps (CORINE) and geographic database (PLI), aggregated into a set of five damage categories. Recently developed damage functions, which are the key part of the vulnerability analysis, has been chosen in relation with the damage categories indentified in the exposure analysis. To determine the value of the assets, a monetary approach has been employed, with the purpose of assessing prices per square meter for each damage category. In this paper, the focus is set on comparing several approaches to calculate the specific price of the residential damage category in Wallonia, and to compare with an existing micro-scale approach (Ernst et al., 2010). [less ▲]

Projet Interreg IVB Amice Rapport intermédiaire d’activité pour le comité d’accompagnement wallon

Report (2011)

Experimental observation of flow characteristics over a Piano Key Weir

in Journal of Hydraulic Research (2011), 49(3), 359-366

The Piano Key Weir is a type of labyrinth weir using overhangs to reduce the foot print of the foundation. These are directly placed on a dam crest. Together with its high discharge capacity for low heads ... [more ▼]

The Piano Key Weir is a type of labyrinth weir using overhangs to reduce the foot print of the foundation. These are directly placed on a dam crest. Together with its high discharge capacity for low heads, this geometry makes these weirs interesting for dam rehabilitation. However, the Piano Key Weir is a new weir type, firstly designed in 2001 and built from 2006 by Electricité de France. Even if experimental studies confirmed its appealing discharge capacities, the flow upstream, over and downstream of this complex structure is still not well known. This research presents experimental test results performed on a 1:10 scale model. The experiments aim at determining the flow features along the weir depending on the upstream head. The flow conditions are characterized in terms of specific discharge, velocity, pressure, water level and streamlines along the weir. [less ▲]

Numerical investigation of flow patterns in rectangular shallow reservoirs

in Engineering Applications of Computational Fluid Mechanics (2011), 5(2), 247-258

The present work gives findings profitable for the person who wants to evaluate an asymmetric detach-reattach flow. In this study, the capability of a two-dimensional shallow-water numerical model to ... [more ▼]

The present work gives findings profitable for the person who wants to evaluate an asymmetric detach-reattach flow. In this study, the capability of a two-dimensional shallow-water numerical model to simulate the symmetric and asymmetric flows that can take place in rectangular shallow reservoirs varying the lateral expansion ratio and the dimensionless length is investigated. For a large lateral expansion ratio, the use of two protocols of simulation highlighted a high sensitivity of the simulated flow pattern to the initial condition. Comparison between simulated results and experimental data showed a good agreement for the critical shape parameter (combination of the lateral expansion ratio and the dimensionless length) between symmetric and asymmetric flows. A good agreement was also found for the value of the shorter reattachment length of asymmetric flows. For small lateral expansion ratios, the agreement was not so good. The model was used for even larger lateral expansion ratios in order to numerically extend the experimental dataset. This predictive work showed that the shape parameter, whose expression was only based on experiments carried out for small lateral expansion ratios, was also relevant for larger values. Moreover, the predicted values of the shorter reattachment length were also consistent with a regression only based on experimental results. [less ▲]

Integrated Two-phase Drift-flux Models for Modeling Sediment Transport

in Proceedings of the Symposium on Two-phase Modelling for Sediment Dynamics in Geophysical Flows (2011, April)

Flood risk management and reservoir operation

in Contribution to the news of Belgian television RTL (2011)