Specials Environment

Updated April 1999

Special: Remote Sensing for Decision-makers

Rangeland assessment and monitoring

Pilot study in Morocco


Introduction | Aquaculture | Forest management | Rangeland assessment | Groundwater exploration | Forest fire management | Forest decline assessment | Crop information systems | Inventory and monitoring of shrimp farms


Arid rangelands account for almost 30 percent of world land area. They are subjected to intensive use (overgrazing, human activity) and severe climatic conditions. Their sustainable management and use can be assured by employing remote sensing and geographic information systems that will enable countries to engage in extensive livestock production while at the same time curbing environmental degradation.


High- and medium-resolution satellite imagery

The availability of high-resolution satellite imagery, such as Landsat Thematic Mapper and SPOT, combined with medium-resolution satellite imagery, such as Landsat MSS, opens up new possibilities for the monitoring of rangelands and offers a number of advantages over conventional methods of observation:


Case study in Morocco: analysis and monitoring of rangelands

Rangeland accounts for almost 80 percent of Morocco's land area and supplies about 30 percent of the feed needed for its estimated 26 million head of livestock (sheep, goats, cattle and camels). Extensive herding on its array of landscapes removes the limited and dispersed forage. The resulting overgrazing associated with socio-economic conditions in rural areas indicates the need for rangeland management and monitoring. The Géostat-Maroc project was therefore initiated to produce a rapid and effective map and statistical inventory of rangeland resources. The approach employed combines high- and medium-resolution spatial imagery with statistical modelling. A GIS was used for rangeland stratification and positioning of the sampling frame.


Map of vegetation (top) and inventory of rangeland facies (bottom) resulting from interpretation of SPOT images


Remote sensing and GIS: decision-making aids

The methodology employed by the Géostat-Maroc project, based on SPOT images and supplementary data (documents and ground surveys), equipped rangeland officials and planners with:


Zoning map with sampling frame

 

Map of rangeland vulnerability


Evaluation and recommendations

Costs and delivery times

 Costs (US$/km2)Time (months)
Rangeland zoning0.175.0
Statistical modelling0.143.0
Rangeland mapping0.6617
Map production0.031
Total1.0026

The evaluation of costs and delivery times is based on an average-sized country and does not vary much from one country to another. The cost is low because no use was made of complete SPOT image coverage; on the other hand, the duration was significant. These estimates will fall by almost one-third, when the project is fully operational, for the following reasons:

A cost-effective technique

The integration of satellite imagery and ancillary data with statistical modelling provides access to updated information for the mapping of rangeland facies, statistical analysis, zoning and identification of vulnerable zones. The building of a database permits the statistical and spatial analysis of data for better understanding, management and use of rangeland resources.

Recommendations

The Géostat-Maroc project resulted in the building of a rangeland database and a monitoring system based on a GIS. The database can be regularly updated (every two to five years for example) according to the degree of environmental pressures on the natural habitat. This methodology can produce a statistical inventory of national rangeland cover with an accuracy as high as 90 percent. It can be easily applied in other countries and regions where rangeland resources are important.

This project was carried out by the Royal Centre of Spatial Remote Sensing (CRTS), the Department of Livestock and the IAV Hassan II (MAMVA), in collaboration with the National Centre for Spatial Studies (CNES), ENSAT, INSEE and Scot-Conseil of France.