Abstract:

Water hyacinth (Eichhornia crassipes) is a notorious weed that can be found in large parts of the tropical world. It infested East African fresh water lakes in the 1980's, soon causing major problems on notably Lake Victoria. Mats consisting of water hyacinth blocked ports along the shoreline of the lake, the generation of hydro-electricity was hampered and the already disrupted ecosystem was further affected. A control program has been initialised, that requires objective and efficient information. The ways to get information about the exact location and the size of the water hyacinth mats need to be improved. The application of remote sensing techniques can realise this improvement. SYNOPTICS and FIRI have carried out a project to investigate the potentials of spaceborne Synthetic Aperture Radar to detect water hyacinth mats on Lake Victoria. ERS, Radarsat and SIR-C data were acquired to evaluate the different sensors. The evaluation showed that in particular Radarsat data are well suited to identify and map the mats. New sensors, both in the optical range and the microwave range, make the perspective of a monitoring program based on remote sensing techniques even better.