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Costa Rica Costa Rica

Latitude: 10° 32' N - Longitude: 83° 38' W

Atlantic coast of northern Costa Rica and south Nicaragua. The river visible in the upper left-hand section of the image is the San Juan river which separates Costa Rica from Nicaragua. The dark lines near the coast are caused by a ramified river system discharging water from the tropical rain forest into the Caribbean Sea. This river system changes greatly over time: after floods new river arms are generated and old ones are cut-off. A comparison of the river system visible on this SAR image with the one drawn on a geographical map (from Charles Sturt University) at three different scales (1, 2, 3), reveals quite significant differences. This demonstrates that ERS SAR images can be used for monitoring changes in river systems in tropical areas.
Costa Rica Costa Rica

Latitude: 10° 51' N - Longitude: 83° 26' W

On this image the same river system is visible as on the previous one. However, this image was acquired one year later during an ascending pass of the ERS-1 satellite, while the previous one was acquired during a descending pass. A detailed comparison of both images reveals that during the one year period the river system has changed.
# Orbit Frame(s) Satellite Date Time Location
1 10906 3393 ERS-1 16-Aug-1993 16:00
2 16260 0207 ERS-1 25-Aug-1994 04:08

If you have any comments on these images please write an e-mail to alpers@ifm.uni-hamburg.de.