The great Okavango Delta in the Kalahari Desert is illuminated in the Sun’s reflection point in this panorama taken from the International Space Station (ISS). Using this sunglint technique, astronauts can capture the fine detail of water bodies.
In this image, the bright line of the Okavango River shows the annual summer flood advancing from the well-watered Angolan Highlands (upper image margin). The flood water slowly seeps across the 150 kilometer-long (100 mile) delta—supplying forests and wetlands—and finally reaches the fault-bounded lower margin of the delta in the middle of winter. The wetlands support a highly diverse number of plant and animals species in the middle of the otherwise semiarid Kalahari Desert. For this reason, the Okavango Delta is now one of the most famous tourist sites in Africa.
Most of the water from the Okavango River is consumed by forests or evaporates in the dry air. Only 2 percent of the river’s water actually exits the delta. This photograph shows the small quantity of water exiting through the Boteti River. Okavango water only reaches the dry lake floors (visible on the lower edge of the large image) in the wettest years.
Part of one of the ISS solar arrays is visible on the right.
Astronaut photograph ISS040-E-8209 was acquired on June 6, 2014, with a Nikon D3S digital camera using a 42 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 the Expedition 40 crew. It 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, Jacobs at NASA-JSC.
The Ebro River Delta, located along the eastern coast of Spain, is one of the largest wetland areas (320 km²) in the western Mediterranean region. The Ebro delta has grown rapidly—the historical rate of growth of the delta is demonstrated by the city of Amposta. This city was a seaport in the 4th Century, and is now located well inland from the current Ebro river mouth. The rounded form of the delta attests to the balance between sediment deposition by the Ebro River and removal of this material by wave erosion. This astronaut photograph, taken in partial sunglint, also shows the Ebro’s fresh water lens—the water density boundary between the upper layer of fresh water issuing from the Ebro River mouth and the saltier, denser Mediterranean Sea water.