NDVI change
To compare the progess of the Great Green Wall project in both countries the change in NDVI was calculated.
An overall slight increase in vegetation cover or vegetation vitality can be observed. There are only very small areas where vegetation vitality or cover decreased in both countries.
However the area of the Great Green Wall project is not highlighted by an increase in vegetation cover or vitality. Some of the increase of the NDVI in Mali within the Great Green Wall area can possibly be explained through the corresponding increase in precipitation.
The NDVI increase in Senegal cannot be explained by a higher precipitation as there is a decrease in precipitation for 2019. The Great Green Wall project can have helped to improve vegetation cover and/or vitality but it is very unlikely to be responsible for the overall improvement. Other factors not treated here, would have to be considered.