Delta distributaries (channels and streams) have two morphologies: large and relatively straight or small and highly contorted. In the photo, brown sediment has been stirred up by heavy rains; when it reaches the sea, it is swept north (to the left in this image) by local ocean currents. Clearer blue water is visible to the lower right (south). Over thousands of years, the sediment supplied by the river has been shaped by waves into beach ridges along the shoreline. Those ridges appear as many parallel lines, with each line representing a prior coastline on this fast-changing (geologically speaking) coast. The oldest coastline lies furthest inland.
Four cyclones hit Madagascar in the first four months of 2015. Heavy floods followed a mid-January storm and affected not only the 50 kilometer (31 mile) shoreline of the delta but also the lower 75 kilometers (47 miles) of the river.
Astronaut photograph ISS043-E-101832
was acquired on April 12, 2015, with a Nikon D4 digital camera using a
1150 millimeter lens, and is provided by the ISS Crew Earth Observations
Facility and the Earth Science and Remote Sensing Unit, Johnson Space
Center. The image was taken by a member of the Expedition 43 crew. The image has been cropped and enhanced to improve contrast, and lens artifacts have been removed. The International Space Station Program supports the laboratory as part of the ISS National Lab
to help astronauts take pictures of Earth that will be of the greatest
value to scientists and the public, and to make those images freely
available on the Internet. Additional images taken by astronauts and
cosmonauts can be viewed at the NASA/JSC Gateway to Astronaut Photography of Earth. Caption by M. Justin Wilkinson, Texas State University, Jacobs Contract at NASA-JSC.
- Instrument(s):
- ISS - Digital Camera
