On google earth timelapse you can see how the Aral Sea shrivels up to almost nothing. The Aral Sea is fed by the Amu Darya River in the south and the Syr Darya in the east/north. The Aral Sea began drying up after the Soviets began diverting the rivers for irrigation. By 2007 it was just 10% of its original size. The dried up basin is now a desert called the Aralkum desert. This just shows how important rivers are, and changing their paths can lead to devastation of areas that relied on the rivers.
Search Aral Sea on google earth timelapse