MONITORING PLAYA SEDIMENTATION USING SEQUENTIAL RADAR IMAGES

A series of ERS-1 radar images of the Chott el Djerid playa in Tunisia obtained at intervals of 35 days demonstrates the ability to monitor geological change from space. The C-band radar backscatter is shown fr om field measurements to be sensitive to changes in surface roughness at millimetric scale due to evaporative growth of halite and gypsum cr ystals. Backscatter increases gradually during the dry summer months a nd decreases rapidly in early winter as the rains begin. Episodic hydr ogeological and sedimentological events including lake development, ch annel flow and aeolian deposition can also be detected in addition to the seasonal pattern. Multitemporal, spaceborne radar offers the prosp ect of being able to map the dynamics of evaporite sedimentation in co ntinental playas.