Étude de la connexion hydrologique entre le Blanc-Ry et l’étang de Warlongroux

Details

Supervisors

Soares Frazao, Sandra

Faculty

Ecole polytechnique de Louvain
Ecole polytechnique de Louvain

Degree label

Master [120] : ingénieur civil mécanicien, à finalité spécialisée
Master [120] : ingénieur civil des constructions, à finalité spécialisée

Abstract

enWaterways and associated natural environments offer a variety of services to the riparian populations. Beyond the economic interest they represent, these environments offer a living environment suitable to the development of biodiversity, but they are fragile and any development project is likely to affect their balance. The Warlongroux pond, in the Lauzelle forest in Louvain-la-Neuve, Belgium, is one of these natural wetlands. Its management is now being questioned because a renaturalization project is under study. Indeed, the management of a pond such as this one requires a decennial draining which creates an ecological rupture. As part of this project, the idea of connecting the Blanc-Ry to the pond is considered in order to establish a hydrological and piscicultural connection between them and to put an end to the regular emptying of the pond. The objective of this thesis is to study the hydromorphological and sedimentological phenomenons taking place in the pond. Different parameters and arrangements will be studied to offer a clearer vision of the possibilities and limits of this project. In order to better explain the situation, the stakes and our role in the project, this presentation will be organized as follows. Once the site is located, the history of the site will be outlined, then the physical characteristics of the environment will be determined, which will allow us to simulate the flow in the pond. Finally, thanks to the results obtained, a set of recommendations for the development of an efficient renaturalization will be proposed. The sedimentological parameters and the flow rate of the source that already flows in the pond were measured on the field. The bathymetry of the pond was modeled by deploying a drone and using photogrammetry software. Then different parameters were selected: flow rate, point of injection, variation of the inlet flow in case of flooding and addition of emergent groynes. Simulations were used to test the influence of these four parameters. Without any arrangement and outside a flood event, the position of injection does not significantivly impact the transpot of sediments which tend to accumulate at the inlet. The collected discharge, increase the recirculations slightly. During the peak flow of an annual flood event, the area of sediments transport extends to a third of the pond. The consquent sudden increase of discharge bring an elevation of the water level in the pond. A metastable stable state settles between the successive flood. Thus it seems judicious to maintain temporarily the pond in its current state to let the time to study the installation of a thoughtful protocol of development in a systemic way.