Coastal wetland landscapes have undergone major changes through their use, protection and appropriation. Often developed for anthropogenic purposes, but also protected for their natural characteristics, they are now facing an increased risk of flooding due to climate change and the rise in the sea level. A prospective approach is frequently used to consider the development of these areas and requires a good knowledge of the trajectories of coastal wetland landscapes, as well as their development and past uses. Using a geohistorical approach, this article proposes a method based on the analysis of digitised georeferenced historical maps detailing land use to reconstruct the trajectories of these landscapes. An example of this is the Corsept marshes in the region of Loire-Atlantique. The study of this marshland makes it possible to identify the different changes and the paces at which they occurred in this area protected for its natural characteristics and to understand the social and natural heritage passed down since the 18th century. Following an analysis of the archives, the results of this quantitative method are discussed and a critical review is made of the contributions of the approach.