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September 7, 2012 7:43 pm
Well, it’s official. According to the National Climatic Data Center of the US National Oceanic and Atmospheric Administration, July was the hottest month on record in the contiguous states of the US: an average of 77.6F (25.3C), which is 3.3F above the average for the 20th century.
For the rest of the world it was pretty warm too – in fact the fourth-warmest since records began in 1880 (the northern hemisphere land surface temperature was 2.14F above average). In many parts of the world, including more than half of the states of the US, drought conditions prevail. In the UK, where I am writing this, we have just emerged from the wettest summer for a century. The fact is that you just can’t trust rainfall anymore; either it deluges for months on end or doesn’t rain at all.
As so often, problems that seem immediate and modern have been faced by humankind for centuries. Ever since people settled in one place for longer than a single night, a source of water has been fundamental to their choice of location. From the moment settlements expanded beyond a small number of families, provision had to be made for water supply from streams, springs, wells or simply catching raindrops. When cities developed, supplying water became the overriding priority.
Sextus Julius Frontinus, the water commissioner of ancient Rome in the AD 90s, believed that the maintenance of the city’s aqueducts was the “best testimony to the greatness of the Roman Empire”. You can hardly doubt him when you visit a remaining section of ancient aqueduct such as the monumental Pont du Gard in Provence. This vertiginous structure built to supply the town of Nîmes with water is, in my view, the archaeological highlight of the south of France. It carried water from a spring some 12.5 miles away, mainly underground but at one point spectacularly on a three-tier aqueduct 164ft above the river Gard below.
The Alhambra of Granada in Spain had originally been supplied by a cistern filled with rainwater but the building of acequias (open runnels) to convey water from the river Darro five miles away transformed it into the earthly paradise of gardens, fountains and pools that we can see today.
Aqueducts are all very well for palaces or towns but for individual dwellings the well is among the oldest man-made methods of reaching pure water. The United Nations Environment Programme estimates that only 0.3 per cent of the world’s freshwater is in rivers and lakes; 70 per cent is locked in ice and snow; and 30 per cent is groundwater. This means that something like 97 per cent of all drinkable water is groundwater. To reach it, well technology has evolved all over the world from early times.
At the heart of Dover Castle on the south coast of England is King Henry II’s masterpiece, a tower designed to be seen from his lands in France. Built in the 1180s the tower is constructed round a well sunk more than 400ft deep into the chalk. Hand-digging to such a depth was difficult and dangerous and, once completed, raising a single bucket was laborious.
There were various ways of getting round the slowness of raising water from a well. Recently the Museum of London excavated, in Gresham Street, in the centre of the City, a Roman well complete with its water-lifting mechanism. This remarkable contraption had a chain with oak buckets that would have been turned by a treadmill. An alternative method, where there was enough space, was to make the well wide as well as deep.
This is what is found at the fortress at Kumbhalgarh, north of Udaipur in Rajasthan, India. This gigantic castle makes Peter Jackson’s fortresses in his Lord of the Rings films look like a failure of imagination. Its perimeter walls are 12km around and five metres thick, with 10 great gates. More than just a stronghold, it was set up to support a large population and had 360 temples, but of all the remains the most amazing is the step well.
This is a type of well common in western India and some parts of Pakistan whereby the extreme depth of the well is made accessible by digging out a huge area and stepping it down to the reservoir at the bottom. The step well tells us a great deal about attitudes to water because it is architecturally extremely elaborate, much more so than its function demands. Water on tap has always been a sign of status. It was also a sign of power; the Kumbhalgarh well was surrounded by its own stout wall – the only time the fortress fell was because its water supply was compromised.
None of these wells was as efficient as an aqueduct, which produced a continuous stream of water, but in the 19th century the artesian well was perfected, mainly in France, taking its name from Artois where it was supposedly invented in 1126.
The principle is a simple one but requires knowledge of the underlying geology and quite sophisticated boring technology. A small bore pipe is sunk to an aquifer lying between two impervious strata. Assuming that there was adequate head, water released from underground confinement is forced up the pipe and released at ground level, without the need for pumping. From the early 19th century on, borings were lined with iron tubes, vastly increasing the depth to which a well could be sunk. Before 1841 an artesian well of 1,800ft was sunk at Grenelle near Paris and by the 1960s American technology was good enough to bring water up from a depth of 7,320ft at Rosebud County, Montana.
The British industrial revolution was driven by the need to pump water from deep mine shafts. Pumping engines have, since then, got smaller and smaller. Since the invention of effective electric immersion pumps, water can be raised from the aquifer cheaply even if you don’t live in an area with suitable geology for an artesian well. In the UK private individuals are now permitted to draw 4,000 gallons of water from the aquifer each per day without a licence, enough to water a herd of cattle – most domestic users would consume a fraction of this. This summer I stayed with friends who had their own borehole. Freed from anxieties about drought, they enjoyed their own freshwater supply at the table and in the garden.
It was perhaps the religious and symbolic role of water in cleansing the body and soul in both Muslim and Christian traditions that made it so integral to European medieval monasteries. It has always surprised me how sophisticated the water supply systems of abbeys were in comparison with the average medieval castle. Running water for hand-washing and flushing latrines was commonplace if you were a monk, but a wealthy knight would often have only a well in his castle and an outshoot for his latrine that dumped his excrement into the moat.
A notable exception is Warkworth Castle on the rugged Northumbrian coast of England. In the late 1370s the first earl of Northumberland commissioned a remarkable cross-shaped tower, a sort of castle within a castle. Even in dry years the rainfall on this coast is high; and because the castle is built on a rocky spur where digging would be hard, the earl’s architect devised a system whereby the rainfall from the extensive areas of leaded roof was channelled down a shaft in the centre of the building to cisterns below. This could either be used for drinking and washing or diverted to flush out the latrines.
Such rainwater harvest or capture is a feature of life for millions across the globe. In places with freshwater scarcity such as the US Virgin Islands, it is compulsory to build harvesting into new construction. In India, China and Brazil massive harvesting projects are under way to prevent rainfall from being flushed away into the drains.
Last month work started on a new museum at Stonehenge. Isolated in the middle of Salisbury Plain, it will be miles from the nearest water main. The building incorporates a pumped borehole 443ft deep for drinking water and its roof is designed to capture the plentiful rain that falls on the plain. More than a million people will use it in its first year and, despite being a building of the 21st century, its water supply technology will be almost as old as the stones themselves.
Copyright for cutaway diagram: Chris Jones-Jenkins/English Heritage
Simon Thurley is chief executive of English Heritage
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