Abstract
Combating desertification in the Southern hemisphere representing 75% of the world population with 75% of them working in the agriculture sector is a priority. Within a GIS platform the paper presents a complete approach to characterizing quantifying and modelling spatially agricultural practices along with available natural resources, both in interaction in a given landscape area. The description of a geocomputational workflow modelling of rural landscapes into units where the causes and intensity of desertification risk can be associated is detailed. The SIEL software allows to set up the parameters of a modelling simulation according to the scientific workflow and to perform its execution. Results over several observatories in the circum-Saharan area are presented. They open the discussion on future and the potential developments of the SIEL in the context of observatories dedicated to support decision making to combat desertification.