Riparian societies, by the different facilities they grafted to streams as well as their uses, upset the balance of water systems. Flooding is, in this context, a response of the natural environment to changes in river morphology and hydrodynamics. Through the example of the Scheldt Valley (France) and the St. Lawrence Valley (Quebec), the objective of this article is to define, using a comparative approach, to what extent societies contribute, to enhance or even create their own vulnerability, in Europe and North America while identifying the evolution of this vulnerability in the two areas considered between the seventeenth and the nineteenth centuries. This article addresses the role of river equipment and riverbed metamorphoses and the influence of social practices in the increased frequency and intensity of floods and therefore vulnerability. Then it comes to measuring the impact of these changes on people and their property in urban, peri-urban and rural spaces. Finally, the emphasis is on the means adopted by communities and authorities to overcome the problem. This translates works of greater or lesser extent, on the one hand, to limit the impact of floods and, secondly, act on the root cause of disasters. In the short term, it is it is to these more or less resilient societies to make such adjustments on the amenities sources of flooding, develop dikes and ditches to contain and dispose of the water. A long term goal is to achieve mastering and managing the river system to prevent flooding, for putting the damage caused by them and develop the territory.