Use of remote sensing for GIS-based early warning and surveillance systems in (agro-) pastoral areas SAHEL

Disaster Type related

Pastoral and agropastoral areas in Mali and Niger extend to more than 1500000 km². These areas are characterized by low intensity rainfall and high spatio-temporal variabilty with the result of significant weakness and fragility of the resources, mostly linked to soil characteristics and rainfall. Accordinglly, the social movementes are variable in terms of periodicity and importance, depending on the availability of the resources.

These movements are conditioned by key factors that make the pastoral comunity vulnerable:
-Low awareness of local environment
-Lack of information related to natural resources
-Unadapted classical methods : tools that are usually used in sedentary context are not fitted to the specificities of nomadic environments.

In pastoral areas, two main resources are to be considered. Pasture and Water.
These fundamental resources are deeply linked with food security for nomadic people within
Sahel and Sahara regions. Thanks to new technologies, it is now possible to realize a regular follow-up of natural resources through the medium of satellite imagery and remote sensing tools.

The general objective of the EWSSS is to reduce vulnerabilities of (agro-) pastoral households and communities to climatic stressors and to prevent humanitarian and nutrition crises in Sahel and in the Greater Horn of Africa.In this sense, two major aspects have been developed: a tool to facilitate the technical implementation of new water points and another, BIOGENERATOR, that allows an automatized analysis of biomass production at national level. The combination of both of them would lead to the identification of pastoral potential space.

The biogenerator is a GIS tool that allows the follow-up of biomass production. Using SPOT vegetation products as input, the output products are the following:

-Yearly cumulative biomass production amount
-Interannual mean biomass production amount
-Anomaly or difference in biomass production compared to the mean value

Movement mapping has been realized on Mali and is on process in Niger and Mauritania. It shows the normal movements and concentration areas of cattle depending on seasonality and climatic conditions (lack of rainfall, unbalanced rainfall coverage). This is used as a base to be compared to the actual situation.
After having considered the main resources and the resulting social movements it is possible to define Agro – ecological zones in order to:

-Consider people and cattle mobility depending on the season (areas complementarity)
-Be able to analyse huge areas
-Go beyond the consideration of administrative boundaries
-Match with the specificities of the area.

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