The recently completed Comprehensive Assessment of Water Management in Agriculture estimates that 1.2 billion people live in areas affected by water scarcity, where water resources are not enough to meet growing needs.

In many of them, people rely on irrigation for agriculture. In India, for example, more than 60 percent of the cereal crops grown for food and feed production are irrigated--and in China, that figure is more than 70 percent.

Irrigation demands large amounts of water, depending on both crop type and region, as well as climate and mode of cultivation (high-input versus low-input agriculture).

For example, one kilogram of Indian rice evaporates an average 1100 liters of irrigation water. A kilogram of wheat in China, by contrast, evaporates 820 liters, Allafrica.com said.

Both China and India, responding to severe water shortages and growing water needs, have already initiated large projects to transfer water from areas of high to low abundance. The South-North transfer project in China and the Linking of Rivers project in India are just two examples. But such projects are controversial because of the high costs, environmental impacts and displacement of people associated with them.

Biofuels Add to Strain

In water-short countries, increasing agricultural production of biofuels will simply add to the strain on stressed water resources. Almost all of India’s sugarcane--the country’s major ethanol crop--is irrigated, as is about 45 percent of China’s top biofuel crop, maize.

The water needed to process crops into biofuel is negligible compared with the amounts that go to growing them. Research at the International Water Management Institute (IWMI) in Sri Lanka has shown that at a global average, the biomass needed to produce one liter of biofuel evaporates between 1000 and 4000 liters of water, depending on the type of feedstock and conversion techniques used.

Sugarcane in Brazil evaporates around 2200 liters for every liter of ethanol. But in this water-rich region, the demand is easily met by abundant rainfall. In more arid countries, irrigation must make up the shortfall. In India, for example, a liter of sugarcane ethanol requires 3500 liters of irrigation water.

More, More, More

As populations grow over the next four decades, demand for food, and thus water, will continue to rise across the world. This is especially true for rapidly developing nations like China and India, where people’s improved standards of living will cause diets to shift towards more sugar, oil, vegetables, meat and dairy products, all of which typically require more water to produce.

Because of their limited water resources, such countries will face serious challenges to meet the predicted increase in demand for food produce, let alone sustain any further growth prompted by expanding biofuel production.

By 2030, India’s demand for cereal is set to rise by 60 percent, and more than double for sugar. Analysis by the IWMI indicates that even under the most optimistic scenario, the demand for irrigation water will increase by 13 percent--equivalent to 84,000 billion liters, or roughly the annual flow of the Krishna River.

Growing sugarcane to produce the 9 billion liters of bioethanol needed to meet just 10 percent of India’s petrol demand by 2030 could add another 22,000 billion liters of irrigation water to the figure. And this is assuming that water efficiency improves.

In China, cereal demand is expected to grow by 45 percent, mainly to feed animals. The amount of irrigation water that will be needed to meet this is estimated at 73,000 billion liters--an increase of 14 percent from current demand for cereal crops.

PIN/ ALLAFRICA.COM