Of dying rivers

In the past, the Hadejia-Nguru Wetlands of northern Nigeria provided fish and vegetables to a million people. When the annual floodwaters retreated, a fishing festival was held, during which young people competed to see who could pull the largest fish from the remaining pools. Today, the lakes are wasting away, the grain is withering under the scorching sun, and fishing nets remain empty. Livestock had to be slaughtered, and trees are so parched due to declining groundwater levels that they no longer attract bees.

In the Anglo-Saxon tradition of scientific essays, Fred Pearce vividly describes what happens when a river dies – whether that happens in Nigeria, the USA or Afghanistan. The journalist and environmental consultant to the magazine New Scientist argues that the fate of our rivers will impact more on humankind than anything else the coming century holds in store. The idea for the book took root when he realised that many atlas maps do not reflect geographical reality. Entire lakes have disappeared – and rivers such as the Nile, the Rio Grande, the Jordan and the Indus no longer really flow into the sea, but seep away in the sand before reaching the coast.

The most significant causes, according to Pearce, are water use in agriculture, household consumption, ground sealing and dam building. River water is apparently becoming so scarce in regions such as the Western United States that underground water reserves have been tapped, which will never be replenished because there is too little rainfall. Pearce points out that half the world’s sustainable fresh water reserves are contained in the territory of only six states – Brazil, Russia, Canada, Indonesia, China and Colombia.

Pearce calls for a “blue revolution” in agriculture. Today, the world grows twice as much food as a generation ago, but, in order to do so, it uses three times more water. Years of irrigation have left a crust of salt on some fields. Huge amounts of “virtual water” are exported from relatively arid to relatively wet regions – for instance, when cotton from Pakistan or avocados from Israel are sold in Europe.

The book touches on a variety of topics – from contaminated well water to climate change to methane emissions from hydroelectric power plants. But Pearce pays too little attention to the economic perspective. Only when he mentions water contracts between the USA and Mexico, or between South Africa and water-rich Lesotho, does he show the extent to which the supply of water depends on money.

For all the graphic and engaging narrative, sometimes the reader can’t help wishing for a little more in-depth information. For instance, Pearce does not explain on what kind of calculation he based his “virtual water” claims on. Nonetheless it is astounding to read that it takes 100 litres of water to grow a portion of rice, 150 for a slice of toast, 500 for a two-egg omelette, and 5000 litres for a small steak. For sugar, coffee and alcohol the cost factor is especially significant. Whoever stops to think that a single meal can use up thousands of litres of water?

Anke Schwarzer