Research project T4/DD/05 (Research action T4)
Installing a land use policy aiming at long term sustainability needs to be based on a sound knowledge of the impact of policy measures in the specific environmental, economic and sociologic context of the region at stake. Adapting the management practices of the natural resources to support a growing population pressure and at the same time guarantee long-term environmental stability, has become a high priority task in the tropical regions.
Remote sensing techniques can contribute significantly to the assessment of the current status of the environment, evolution monitoring and management control, and to environmental impact evaluation. The launch in the early nineties of the operational satelliteborne Synthetic Aperture Radar (SAR) sensors has improved the image availability over tropical regions. These active imaging systems operating in the microwave domain allow for the acquisition of earth observation data day and night, and regardless the atmospheric conditions.
The proposed research project seeks to work out an adapted rationale for interpreting SAR image data over tropical vegetation based on the formulation of the physical interaction of the incident wave with the target and its relevant characteristics.
By providing a physical basis to the development of the image interpretation techniques for mapping and quantitative information extraction, a method is worked out that can be repeated under different situations in time and space.
The further development and dedicated application of radiative transfer modelling takes a central position in this approach. Iterative sensitivity analysis aims at realistic target properties of the vegetation and parameters varying with the vegetation and environmental conditions. Guidelines for the image interpretation are formulated regarding the driving factors behind stable and dynamic components of the vegetation types studied.
Two of the operational spaceborne SAR instruments (ERS and JERS) operate at different wavelengths, and are therefore expected to contain complementary information due to the sensitivity for vegetation elements of different size. Comparable analyses regarding the thematical issues at stake are proposed.
The sequence of elaboration of the thematical study topics is determined by an approach narrowing down from the general to the detailed, both in a spatial and a thematic perspective.
Starting with the delineation of the large land-cover units, the foundations are laid for the analysis of the phenologic features of selected representative land-cover units, as .as for the analysis of the composition and structure of the forested areas.
This will reflect in the sequence of elaboration of the dedicated SAR image processing tools, as they are tuned on the spatial and thematic needs of the study elements.
