Earth Observations taken by the Expedition 17 Crew

ISS017-E-008290 (31 May 2008) --- Toshka Lakes in southern Egypt are featured in this image photographed by an Expedition 17 crewmember on the International Space Station. In the late 1990s, Egypt's new manmade Toshka Lakes, fed from Lake Nasser via a new canal, grew and spilled into new basins to become four major and two smaller waterbodies extending 120 kilometers across the desert west of the Nile River in southern Egypt. Starting in 2002, astronauts have seen the lakes slowly decline, with the telltale ring of darker, moistened ground showing the previous higher water levels. The rise and fall of Toshka Lakes, and the economic development surrounding the region, are dependent on climate fluctuations and water agreements with upstream countries that, in turn, determine the long-term water flow in the lower Nile. This view, covering a distance of 11.3 kilometers from bottom to top, shows shoreline detail of the third large lake. Lake water appears deep blue to blue-green, and parallel with the shoreline is a wide brown zone which was under water until 2002. Most of the bright yellow sand dunes in the view are re-emerging as the lake level drops, most outlined visibly by thin wet margins. Still-submerged dunes can be seen as small gray blebs offshore (left center). The summit of the biggest horn-shaped dune (top left) was an island more than 5 kilometers off shore in images from 2001. The dune pattern gives a strong sense of dune migration southwards, from top left towards lower right (horns of crescent dunes point in the direction of dune movement). Dominant northerly winds drive the dunes southward, except, of course, when they are under water.