Towards a better use of rainwater in urban areas through quantitative assessments of water flows : application to the Espierres watershed

The number of urbanized cities is increasing in the world. This urbanization raise concerns in several areas, specifically during major rain events. Urbanization and especially imperviousness prevents the rain from infiltrating and causes floods like those of July 2021. In addition, natural water resources on earth are limited. Water stress is increasing in most countries. In particular cases, such as Belgium, it would be possible to avoid this water stress by filling the water tables with rainwater. The aim of this graduation study is to improve the use of rainwater in the urban environment. On the one hand, reduce runoff on urban areas, and on the other hand avoid flooding due to sewer overflows. To do this, simulations at two different sites have been carried out on the SWMM software which allows to represent an urban area and its flows. This work highlights the approach to be taken for modeling urban areas on the SWMM software and flow mitigation measures on various terrains under various rain conditions. It shows that depending on the catchment, the size and the duration of the rain, the choice of the mitigations solutions is really different. Also, private and public domain should be more studied before the construction of a new residential area. Some guidelines can be implemented in the private domain in order to decrease the runoff.