The Sahel is an area that, over time, has had multiple definitions, climatic-botanical and political: its limits have been traced in very different ways. Even the usage of this name and its delimitation on maps has been openly questioned and contested. Our contribution proposes a cartography capable of mapping the incessant movement of conditions, limits and possibilities that characterize this strip between the Sahara and the humid Sudanese regions, rendering the areal definition of the Sahel visible and fluid at the same time. However, it is a question of rethinking the very foundation of cartography – what has been ‘taken for granted’ in the past – such as the common tools of cartographic representation, for example the concept of ‘isohyet’ to identify climatic areas or ‘boundaries’ to define political jurisdictions. Knowledge from fieldwork and expertise in the processing of satellite and geo-referenced data converge in this path of analysis and representation.

The Great Green Wall (GGW) Initiative comprises 21 African countries and is implemented under the coordination of the African Union.

Humans need increasingly more biomass for food, fodder, fiber and energy. In Africa, circa 22% of the vegetated land surface showed a decline or unstable land productivity between 1999 and 2013. Persistent reduction of land productivity points to long-term alteration of the health and productive capacity of the land, which are characteristic of land degradation. It has impact on ecosystem services and benefits, thus on the sustainable livelihoods of human communities. This map shows the dynamics of (vegetated) land productivity over a time period, in other terms the trajectories of above-ground biomass. It reflects changes in ecosystem functioning e.g. vegetation growth cycles due to natural variation and/or human intervention, and can be associated with processes of land degradation or recovery. The 5 classes depict two levels of persistent productivity decline, one level of instability or stress in capacity, one level of stable productivity and one level of increased productivity.

The Sahel is an area that, over time, has had multiple definitions, climatic-botanical and political: its limits have been traced in very different ways. Even the usage of this name and its delimitation on maps has been openly questioned and contested. Our contribution proposes a cartography capable of mapping the incessant movement of conditions, limits and possibilities that characterize this strip between the Sahara and the humid Sudanese regions, rendering the areal definition of the Sahel visible and fluid at the same time. However, it is a question of rethinking the very foundation of cartography – what has been ‘taken for granted’ in the past – such as the common tools of cartographic representation, for example the concept of ‘isohyet’ to identify climatic areas or ‘boundaries’ to define political jurisdictions. Knowledge from fieldwork and expertise in the processing of satellite and geo-referenced data converge in this path of analysis and representation. The Sahel is a sub-Saharan area defined between the isohyetal lines of 150mm and 850 mm of rain per year. However, depending on the period, the season and the drought / rain conditions this area moves: hence the definition of the breath of the Sahel. This data represents the minimum and maximum extension of the Sahel area over the last 30 years.