Spatial data on vegetation dynamics are sparse for the Djerid oases of Tunisia, but such data are urgently needed by policy makers for natural resource management purposes. These data can be collected by remote sensing and analyzed using Geographic Information System software. We analyzed the changing dynamics of the Tozeur oases in southwestern Tunisia using normalized difference vegetation index (NDVI) index data that were generated from SPOT-5 (Take5) satellite imagery taken from April to September, 2015. We used agglomerative hierarchical clustering (AHC) to produce a dendrogram that segmented the area into similar NDVI classes, then analyzed these clusters with reference to ground-truth data collected by field surveys. The unsupervised classification map produced by AHC represents a spatial model of the NDVI distribution in the oases. The results revealed seven different clusters with very high spatial heterogeneity that were linked to biophysical parameters in the field.
Brasil and Bolivia have water plans projects on the Beni-Madeira river, a major tributary of the Amazon. There are four
main tributaries to the Rio Madeira: the Guapore, the Mamore and the Beni rivers into the Bolivian territory, and the
Madre de Dios River crossing the North of Bolivia, coming from Peru. Most parts of these rivers are very far from the
Andean capital cities of Bolivia and Peru, unreachable for long periods of time. Very few gauging stations are in
operation, either for the Bolivian or the Peruvian part, most of them being located at the Andes piedmont or near the
confluence at the Brazilian border as they form the Madeira river. This situation is exemplary of large transboundary
basins in the tropical part of the world.
We have computed 39 water level time series using ENVISAT altimetry data over the four tributaries of the Madeira and
the Madeira itself. We present a preliminary study mostly conducted onto the Guapore river, in order to assess the quality
of these time series for a variety of situations, but mostly narrow and meandering riverbeds. Comparison between water
levels variation in the mainstream and within the inundations plains and lakes are drawn. We conclude by the
perspectives offered by the combined use of radar altimetry and SAR imagery for the global monitoring of water
resources, in large tropical transboundary basins.
SC924: Remote Sensing Techniques and Developments for Watershed Monitoring in Tropical Countries
This course provides attendees with a working knowledge of Remote Sensing capabilities in high tropical island environments, including cloud covers, flattening, atmospheric correction, mixed and dense vegetation cover distinction, and water monitoring and managment. The course concentrates on optical and radar system performance optimization and analysis.
The first section of the course concerns the ungauged basins and the global monitoring of water resources. Dynamics and water residence time combining radar altimetry and SAR images show the exchanges process of water between the floodplain and the river. Results will be presented and discussed.
The second section will examine experiences and methodology of the use of radar imagery for forest management and grass biomass. It then covers an original approach for radiometric (atmospheric) and geometric (flatenning) correction effect, which will be examined in the context of a project dealing with erosion problems in New Zealand (J. Dymond work). Examples on change detection on forestry issues will also be presented.
The final section of the course analyzes a study in the Solomon Islands area, where SOPAC set up water catchment monitoring GIS layers. The example to be shown will cover a study on overlay analysis in raster data environment (ERDAS).