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The Piano Key Weir (PKW) is a particular geometry of weir associatingto a labyrinth shape the use of overhangs to reduce the basis length.The PKW could thus be directly placed on a dam crest. Together withits important discharge capacity for low heads, this geometric featuremakes the PKW an interesting solution for dam rehabilitation. However,its hydraulic design remains problematic, even at a preliminary stage.This paper presents a preliminary design method based on resultsof experimental tests. The method enables to design project modelsby extrapolation of characteristics of existing idealized scale models.A practical application is presented to illustrate the method.

In hydrology, the modelling of urban areas significantly differs according to the catchment size and the temporal resolution of the studied rainfall events. At small scales, the urban areas can be modelled using a detailed description of the various existing flows, with an explicit description of the drainage network. However, at large scales, the urban areas are often represented by coarser approaches. The current models often take into account impervious surfaces by an adaptation of runoff or infiltration coefficients. In this way, the volume of streaming can be correctly generated, but the modification of the flow dynamics through the drainage network is not taken into account. An original modelling method was thus developed to include these processes in a global hydrological model (WOLF), by accurately quantifying the contributions from impervious surfaces thanks to vectorial landuse maps and propagating them without modelling the whole drainage network. These developments were applied to the Berwinne catchment, in Belgium.En hydrologie, la mani?re de prendre en compte les zones urbaines diff?re sensiblement selon les dimensions des bassins et la r?solution temporelle des ?v?nements pluvieux ?tudi?s. A petite ?chelle, les zones urbaines peuvent ?tre mod?lis?es gr?ce ? une description d?taill?e des divers ?coulements existants. En particulier, le r?seau de drainage peut ?tre d?crit explicitement. A grande ?chelle cependant, les zones urbaines sont souvent repr?sent?es par des approches moins d?taill?es. Les mod?les actuels prennent g?n?ralement en compte les surfaces imperm?ables par une adaptation des coefficients de ruissellement ou d'infiltration. Cette approche permet de g?n?rer des volumes de ruissellement corrects, mais ne permet pas de tenir compte de la modification de la dynamique de transfert des apports li?e ? la pr?sence de r?seaux de drainage. Une m?thode de mod?lisation particuli?re a donc ?t? d?velopp?e pour tenir compte de ces ?l?ments dans un mod?le hydrologique global (WOLF), en quantifiant de fa?on pr?cise les apports des surfaces imperm?ables gr?ce ? des donn?es d'occupation du sol en format vectoriel et en les propageant sans devoir impl?menter l'enti?ret? du r?seau de drainage. Ces d?veloppements ont ?t? appliqu?s sur le bassin de la Berwinne, en Belgique.

The numerical models for flow and sediment transport must be able to handle properly the wide range of space- and time-scales relevant for the processes to be modelled. For this purpose different levels of numerical coupling between the flow solver and the sediment transport model must be considered. Besides a short review of the mathematical background, the present paper describes the modelling system WOLF, developed at the University of Liege and enabling to handle the vast majority of time scales characterizing practical applications of flows with sediment transport, by means of specific numerical techniques. The applicability of the modeling system is demonstrated based on several examples of simulations related to the design and the operation of a large hydroelectric project in India.Les mod?les num?riques hydros?dimentaires doivent ?tre aptes ? prendre en compte la tr?s grande h?t?rog?n?it? des ?chelles spatiales et surtout temporelles affectant les divers ph?nom?nes ? simuler. Pour ce faire, diff?rents niveaux de couplage entre sous-mod?les doivent ?tre pr?vus (calcul hydrodynamique stationnaire, quasi stationnaire ou instationnaire complet). Outre une discussion du formalisme math?matique sous-jacent, la pr?sente communication d?crit le syst?me de mod?lisation WOLF, d?velopp? ? l'Universit? de Li?ge et permettant de couvrir la majorit? des ?chelles de temps pertinentes au moyen d'approches num?riques sp?cifiquement adapt?es. L'applicabilit? du syst?me de mod?lisation est illustr?e sur base de plusieurs exemples de simulations relatives ? la conception et aux modes de gestion d'un grand ouvrage hydro?lectrique en Inde.