The last in a four-part investigation into the state of the world's water resources. The River Runs Dry
In the United States, a series of dams ensures that the Colorado River dries up before it reaches the sea. In India, thousands must abandon villages drowned by a man-made lake. Andy Kershaw weighs the environmental and human costs of building dams against the need for supplies in an increasingly water-scarce world. Producer Jeremy Grange