Battling Drought: The Science of Water Management

billion on the ocean and 80 billion on the land. Over the ocean 9 per cent more water evaporates

few industries account for some two-thirds of all the demand: they are metals, chemicals and petroleum refining, pulp and paper manufacturing and food processing.

on average, each person on the earth needs a minimum of 1,000 cubic meters (m3) of water per year—equivalent

for drinking, hygiene and growing food for

Industrial water requirements for washing, cooling and the circulation of materials range from one to two tons per ton of product in the manufacture of brick to 250 tons per ton of paper and 600 tons per ton of nitrate fertilizer.

Investments in the development of water resources have rarely exceeded 1 or 2 percent of the gross national product. In most countries they cannot be raised much above that level without causing hardship elsewhere in the economy. Capital is a resource in shorter supply than water, and the same strategies must be adopted for its conservation.

the major river valleys will surely remain the primary focus of human civilization, as they have been for 6,000 years. They supply both the land and the water resources needed for irrigated agriculture. Moreover, because the rivers offer abundant water both for consumption and for transport they are also the logical site of major industrial develop

Illiteracy, malnutrition and disease; poverty so harsh that the farmer does not dare risk innovation because failure will mean starvation; small and fragmented farm

For example, about half the water provided for irrigation is lost in transport, and less than half the water that reaches the fields is utilized by plants.