Polygons representing runoff water retention basins at a resolution of one meter in order to identify the physical particularities of the territory. Runoff is defined as the flow of rainwater to the surface of the ground that does not evaporate and does not seep into the ground when the capacity to hold water and vegetation is reached. The [Climate Plan 2020-2030] (https://portail-m4s.s3.montreal.ca/pdf/Plan_climat%2020-16-16-VF4_VDM.pdf) aims, among other things, to improve urban planning and regulatory tools. Montréal is committed to updating the climate change vulnerability analysis carried out as part of the 2015-2020 Agglomération de Montréal Climate Change Adaptation Plan and to integrating it into the next urban planning and mobility plan. The map of runoff water retention basins was produced in 2021, with the collaboration of the Department of Geography of the University of Quebec in Montreal, to calculate the vulnerability to heavy rains in the agglomeration of Montreal. The data can also be consulted on the [interactive map of vulnerabilities to climate hazards in the Montreal agglomeration] (https://experience.arcgis.com/experience/944e0b7104bd491591ccca829da24670/page/Page/).**This third party metadata element was translated using an automated translation tool (Amazon Translate).**