Introduction

Pearce has chronicled the ambitions, achievements, follies and disasters and the sheer perversity of our attitude to and control of water. Water is essential to life on earth, it covers most of the planet, yet many countries are short of water; they import virtual water by buying food they are unable to grow, the virtual water being integral to the food.

We have mismanaged a fundamental resource and with climate change it has been predicted that future wars will be about water.

Pearce writes, “The good news is we never destroy water. We may pollute it, irrigate crops with it or flush it down the toilet. We may even encourage it to evaporate into the air by leaving it around in large reservoirs in the hot sun. But somewhere, sometime, it will return, purged and fresh … .”

Water is used for drinking and agriculture; fish are a valuable source of protein for millions people; water is the only means of transport in many parts of the world; rivers and lakes, if unpolluted, are teeming with wildlife and are a valued for sport and tourism. At the same time we value water for its aesthetic properties. But we mismanage it.

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We waste water

Thames water in the UK looses 100 litres every day for every home it supplies through leaks and London looses about one third of its water through leaks. Yet householders are urged to turn off their taps while they clean their teeth and to install ‘hippos’ in their toilet cisterns. Thames’ solution is to build a £700million reservoir covering 10 sq kilometres near Abingdon.

Wessex Water takes a billion litres from the headwater of the sensitive chalk stream on Salisbury Plain while loosing 2billion litres a month in leaks. Wiltshire MP, Robert Key, describes it as the ‘economics of the madhouse.’

We try to control water, but the consequences are not what we expected
In China there are plans to flood the Three Gorges on the middle reaches of the Yangtze River and create a reservoir 300Km long. It will displace 1.5m people, flood a huge area of fertile land and obliterate a dramatic landscape which is a tourist attraction and has been painted many times in the last 1000 years.

Dams and yet more dams
The World Bank appointed a World Commission on Dams which reported in 2000; after spending $75b on building dams in 92 countries in the previous 50 years, the World Bank had begun to doubt their value. The report was worse than they had expected.

• Average cost over runs stood at 56%
• Half of the hydroelectric dams produced significantly less power than expected
• Two thirds of the dams built to supply cities with water provided less than promised
• A quarter supplied less than half what had been anticipated
• A quarter of dams built for irrigation watered less than 35% of the land intended
• And dams that promised to protect against floods have ‘increased the vulnerability of the river communities to floods,’ often because reservoirs have been kept full to maximise hydroelectric production

How much water is there
There is the slow water cycle with water tied up in oceans, icebergs, glaciers, plants and animals. Although 500,000 cubic kilometres flows though the fast cycle annually, the most we can catch and use is 14,000 cubic kilometres, but the biggest rivers flow through uninhabited regions so 5,000 cubic kilometres is out of reach and only 9,000 cubic kilometres is available. That’s 1,400 cubic metres a year for each person on Earth - Pearce estimates he needs 1,500 – 2000 cubic metres yearly and he lives in the UK which has low water use because of our climate.

The Palestinian enclave on the Gaza strip has only 140 litres of brackish underground water a day for each person. While Greenland has 30,000 available for each person daily, but they don’t need it as they don’t irrigate crops.

As he notes elsewhere where water is concerned it’s – Location, location, location.

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What we are doing to be better managers

What Pearce does in this enthralling and unsettling book is give us hope for the future. He looks at rainwater catchment systems which have been in use for centuries. Qanats in the Middle East and Iran are tunnels which bring water to settlements from aquifers. They are self regulating as they only tap water up to the limit of natural replenishment.

In Europe we are undoing some of our grand schemes for controlling water. In the UK we are reflooding ancient flood plains to avert major disasters such as London flooding. Also letting salt marshes re-emerge to reduce the impact of the sea on coastal regions. But we still haven’t mended those leaking water mains, many of which are 150 years old and are taking greater volumns of water at higher pressure.

The water companies still think big – a national water grid to move water to the south east; another reservoir.

In Germany priority is being given to finding ways of lowering floods on the Rhine. Drained and dyked fields will be replaced with reed beds and water meadows which will flood in winter. In 2003 the German environment minister announced legislation which will, “give our rivers more room again; otherwise they will take it for themselves.”

The Potsdamer Platz in commercial Berlin has been designed to store 1/6 of the annual rainfall it receives and re-use most of the rest.

Los Angeles has launched a $100million feasibility scheme, the porous city, in a poor, flood prone district. The aim is to catch rain from hard surfaces and roofs before it drains away. Trees will soak up water on parking lots and roof water will be used for watering gardens and parks. Road drains will empty into old gravel pits and other porous areas to recharge underground reserves.

There are other ancient methods of collecting mist or fog such as hollow stone pyramids, but these lie in ruins. In Chile large sheets of plastic mesh were suspended along a hilltop in the Atacama Desert. It does not rain there for years on end, but fog rolls in from the Pacific Ocean. Fog gathered on the nets, formed into drops and fell into a trough; 75 sheets yielded 15,000 litres a day. The sheets have been abandoned when the government installed piped water at a cost of $1m, but the idea has been copied elsewhere in South America.

Schemenauer who developed the technology originally has taken it elsewhere; in Oman it collected five times as much water as in Chile. The netting has been used to provide water for new plantations – the trees too become fog catchers with their leaves.

Scientists discovered a beetle which has a hexagonal pattern of peaks and troughs, which push tiny droplets of water together to form larger ones, which roll into the beetle’s mouth. A prototype fog catcher based on the beetle’s design proved to be five times more efficient than Schemenauer’s original net, has been patented.

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Water for agriculture
The green revolution increased crop yields, but required huge amounts of water. The new philosophy is more crop per drop. Simple changes in farming methods can save water including restoring humus to the soil which retains moisture. Rice varieties that can be sown directly into wet soil require a fifth less water than rice which is grown in nurseries and planted into flooded ground. As rice needs twice as much water as wheat, this is significant.

Enterprising farmers in India discovered they could use the plastics lollipop tubes (Pepsees) for irrigation. Water flows along the tubes and leaks out of the perforations, delivering water sparingly. As the tubes were clear plastic algae grew in them, but the manufacturers produced black Pepses which solved the problem.

Pearce has written a highly readable book. The book is packed with information, yet it tells a story, even though it is one we may not want to hear. He doesn’t shy away from writing about the politics of grand schemes; hubris is the word that springs to mind about many of them. Pearce also factors in the effects of climate change – glaciers in the Himalayas and Tibet feed seven of the greatest rivers in the world, ensuring reliable water to 2 billion people. As these glaciers retreat and fail to replenish the rivers, Asia will be left with rain from the mountains which is not so reliable.

Although Pearce notes that our climate change models are models and we do not know what challenges we will face, he is optimistic about how we will manage water; the consequences of not doing so could be catastrophic.

When the rivers run dry. Fred Pearce. Eden Project Books. £18.99
ISBN 1-903-91957-6.
www.booksattransworld.co.uk/eden

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