Seasonally dry salt lakes and the traces of ephemeral streams occupy many of the valleys of the Zagros Mountains in southern Iran. Much of the time, the rivers and lakes are dry above ground, but subterranean water flows along the same pathways. Where these subterranean streams flow out of the mountains, the water table comes closer to the surface, and it is more readily accessible through wells. This simulated natural-color image of southeastern Fars province in southern Iran shows a dry riv...