APPLICATIONS

 4-2 ENVIRONMENTAL STUDIES

Developing a basic documentation on the land use of a region and understanding the driving forces affecting it are essential ingredients in the development of regional planning and more specifically in the definition of sustainable development practices. Changes in land use and the associated land cover are significant to a range of issues central to the study of global environmental change. These considerations which obviously present various levels of relevance and urgency depending upon the area of the world call for the development of approaches to the monitoring of surface conditions along a broad range of scales and frequencies. Dealing with the complex geometry of extensive and changing landscapes represent a major challenge in this respect.

The use of high resolution satellite images has become a standard procedure in the production of land use and land cover maps over the last 20 years. The scale of such maps is usually between 1/50,000 and 1/500,000 which makes them suitable for land resource management at local and regional scales.

In parallel, small scale mapping (1/1 to 5 million scale) is currently experiencing what can be properly called a revolution thanks to the development of low resolution satellite imagery. So far, maps at those scales were obtained by synthesising larger scale maps through a so-called generalisation process. Such operation has often relied on old and outdated information which needed to be interpreted or even heavily extrapolated in case of missing data. It is now possible to replace this generalisation process by accumulating direct observations over areas ranging from continents to the globe.

The maps derived from such data base are homogenous in terms of support , are fairly recent and can be regularly updated. The low resolution data produced by the AVHRR instrument are now intensively used for such purpose. An attempt is currently made under the International Geosphere Biosphere Programme (IGBP) to map the entire surface of the earth using such low resolution information. The feasibility of using such technique was demonstrated in various instances. The scope of such small scale land cover and land use mapping is to complement rather to replace large scale maps. General information of such kind is, indeed, found very adapted to guide the definition of strategies for environmental planning in many parts of the world.

Because of its advanced characteristics in terms of data quality and production the VEGETATION instrument will open new avenues for small scale land cover mapping. Thanks to the simultaneous acquisition of low and high resolution data with, respectively, the Vegetation and the SPOT HRVIR, the validation procedure will be largely facilitated.

To illustrate these advantages for environmental purposes, 3 studies conducted during the pre-launch phase are presented:

As a whole the VEGETATION system is such that the analyst will be in better position to focus upon data analysis instead of data processing and thus improve the quality of the results.