Astronaut photograph ISS013-E-76441 was acquired September 4, 2006, with a Kodak 760C
digital camera with an 800 mm lens, and is provided by the ISS Crew Earth
Observations experiment and the Image Science & Analysis Group, Johnson Space
Center. The image in this article has been cropped and enhanced to improve
International Space Station Program supports the laboratory 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.
In the last three decades, Egypt has greatly modified a series of lagoons and lakes along the northeast coast of the Nile Delta for the production of fish. Partial sunglint in this astronaut photograph reveals numerous details in one such fishery. Sunglint is light reflected directly back from a surface—usually water—to the viewer (or a camera or satellite sensor). Waves generated by northwesterly winds (lower left to upper right in this view) have created the frond-like sand spit along the coast (image top). Faint sea swells are visible at image upper left as a pattern of dark and light lines. Dark patches in the center of the image are shadows cast by small clouds, which appear pewter-gray compared to the golden sunglint on the watery surfaces below.
Dark, curved lines on the inland (western) side of the spit show old positions of the spit. Most of Musallas Lagoon occupies the lower half of the image. By contrast with the spit, the shores of the lagoon are occupied almost entirely by a network of artificial structures—mainly short dikes enclosing hundreds of aquaculture ponds. The total area devoted to fish production in the lagoon is estimated to be 8,000 hectares (19,768 acres), which constitutes more than half of Egypt’s aquaculture production. An outlet to the Mediterranean Sea (top right) allows seawater recharge to the lagoon. Wind helps to circulate the water in this shallow lagoon; bright streaks on the lagoon (lower left) show the north-northwest direction of the wind on this day.
The intense aquaculture in the Nile Delta was born out of the impacts of the Aswan High Dam. The construction of the Aswan High Dam nearly a thousand kilometers upstream stopped the dramatic, and often catastrophic, seasonal floods that previously delivered nutrient-rich sediment from the Nile to the Mediterranean Sea. Nutrient concentration dropped to such a degree that the sea fishery around the delta collapsed in the mid-1960s to about 3 percent of the catch in preceding years. Aquaculture in various parts of Egypt during the last 30 years has partly made up for this loss, and consumption of fish has doubled in Egypt, although exports have not recovered.
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This image originally appeared on the Earth Observatory. Click here to view the full, original record.