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Harvesting rain

Michael Kenneth Cowan

1st June, 2008

Can traditional water-harvesting systems teach us how to solve contemporary water problems? Michael Kenneth Cowan says we have a lot to learn from the ancient and troubled ecology of the Middle East

The Middle East has witnessed a great deal of conflict in times both ancient and modern. At the same time, the ecology of the entire region has shown dramatic declines as a result of polluted waterways, saline soils, contaminated aquifers and much loss of fauna and flora. Yet in areas of this region, which are now relatively lifeless and prone to desertification, there was once abundant wildlife, including elephants and lions, as well as good forest cover.

The cultures of the Middle East also developed extraordinarily clever rainwater harvesting systems, which provided very good supplies of water to towns, villages and individual farms. Such systems are more than just historical curiosities; they may have growing relevance to a modern world in which water is in increasingly short supply.

The area bordered by the Euphrates and Tigris, in what is now southern Iraq, had sophisticated patterns of urban settlement by 3,000BC, with good food production from crops of wheat, barley, fish, meat and wildfowl. Today, we know that ancient trade patterns had an impact on the ecology of the region.

For instance, the Euphrates was used to move commodities between Mesopotamia and human settlements to the north and east. These trade routes along the river stretched from the Persian Gulf to the Mediterranean; ancient commerce flourished up and down the river, with such items as basalt, timber and semi-precious stones like lapis lazuli traded along the length of the river from what is now Iran and Afghanistan. The river’s ancient name was Uruttu, or Copper River, and this metal was brought down to the early Sumerian smiths from the northern hills of Asia Minor. In exchange, the Sumerians traded wheat and barley.

Within a relatively short historical period, however, this increasing pattern of Mesopotamian cereal cultivation for international trade led to problems with salinity, which seem to have been compounded by excessive use of irrigation and poor attention to drainage systems. The long-term results of this are now evident in barren and saline ‘soils’, where agriculture and human settlement once flourished.

The famous Lebanese cedar, Cedrus libani, was already being cut by 3,000BC and later became a mainstay of Phoenicia’s international trade. Around 2,600BC, Egyptian pharaohs imported 40 ships full of Lebanese cedar. The temples of Assyria and Babylon were built out of cedar. Alexander the Great built his Euphrates fleet out of Cedrus libani in the fourth century BC. These wonderful trees, once prolific in Lebanon, Syria and southern Turkey, were decimated in ancient times by local and foreign trade patterns.

More recent times have seen similar patterns of loss of flora and fauna In 1963, Sir Julian Huxley, together with a distinguished group of scientists, went on an expedition to Jordan, with the full co-operation of the then-young King Hussein. The expedition documented in detail the great loss of wildlife such as fallow deer, addax antelopes, the Arabian oryx, ostriches and cheetah that had been quite plentiful at the beginning of the 20th century.

Huxley and his team also documented the massive loss of tree cover as a result of the construction of the Hejaz Railway, between 1900 and 1908, with the felling of large pistachio forests near Karnak and the later destruction of the ‘great oak forests at Shaubak’.

The expedition recorded data suggesting that rainfall in the region had been considerably higher prior to the removal of this tree cover. In relatively recent historical times it was said that a squirrel could have travelled from Damascus to the Turkish border without ever having to get down from a tree. Now, forests in the Middle East are somewhat rare.

Elsewhere in the region, other forces have been at work. The marsh areas in what is now southern Iraq, home to the ancient Mad’an people, provided important winter habitat for millions of birds including pelicans, herons and flamingos, but these ancient marshes were significantly drained by Saddam Hussein.

Out of the ruins

The Middle East is well known for its ancient ruins and remnants of past cultures, but little known is about the great sophistication of the ancient water systems in this troubled region. These cleverly engineered systems could provide practical design ideas for dealing with current, and future, water shortages.

Aside from exploiting water ecologies such as the Euphrates or the once-extensive marsh systems of southern Iraq, ancient peoples of the Middle East, as is often the case today, depended almost entirely on harvesting rainwater.

The Middle East has long dry summers with the possibility of rain only in winter.

In the semi-arid areas of this region, where episodic rain can fall over a relatively small area, sophisticated and often quite large ‘rainfall harvesting’ systems were engineered sometimes covering up to hundreds of square miles. These clever systems collected important quantities of water for human populations and their agriculture.

The ruins of one of the largest of these systems can still be seen in Northern Yemen, and dates back to the time of the Sabaeans (circa 1,500BC-600AD). The Sabaeans, who were superb hydrologists, constructed a complex dry-land water-harvesting system that supplied enough water to irrigate an estimated 20,000 hectares. This system endured for hundreds of years and its demise is mentioned in the Koran. It has been calculated that the agricultural produce of this system could have sustained around 300,000 people.

The Nabateans were also clever hydrologists, as were their Byzantine successors in the region that is now the Negev Desert and western Jordan. Nabatean hydrological technique was adapted to harvest short, periodic flows of water to irrigate fields and to grow grain crops, food trees, grape vines and vegetables. Surplus flow was channelled into limestone cisterns varying in size from capacities of under 20,000 gallons to those much larger.

In the Nabatean capital of Petra, hundreds of thousands of gallons of harvested rainwater could be stored in bell-shaped cisterns, with one cistern cleverly designed to flow into another when full. At Masada, in the Judean Desert, such cisterns could hold around 40,000 cubic metres of harvested rainwater. These useful water-storage systems could hold vast quantities of clean water with little evaporation.

The ancient quanats of Iran transported water over hundreds of kilometres and were still in use in the 1960s but are used much less nowadays. These underground channels brought water from surrounding mountain ranges hundreds of kilometres away to provide for flourishing Persian agricultural sectors in what are dry-land areas.

The remnants of ancient water-harvesting systems, which supplied water for urban populations and agriculture, can be found in different parts of the world. The Sabaeans, Nabateans, Sumerians, Minoans, the people who settled Harappa and Mohenjo-Daro, the Persians, Romans and other ancient peoples were master hydrologists. We know that productive run-off agricultural systems date back at least 5,000 years.

And they can still work today. In the early 1960s, Professor Michael Evenari and a team of scientists established ‘run-off farms’ around Shivta, Avadat and Wadi Mashash in the Negev Desert. Evenari’s project resurrected a series of Nabatean water systems successfully to grow a range of grain, vegetable and food tree crops. The impressive results obtained strongly indicate that these old water systems can be utilised to harvest rainfall for productive human use.

Adapting to the future

A recent edition of the newspaper The Hindu had the vice-chancellor of Mangalore University, B. Hanumaiah, deploring ‘…the tendency to discredit ancient water-harvesting methods in favour of major irrigation projects.’ These traditional engineered systems of rain-fed agriculture were developed over very long periods of time and were designed to accommodate sporadic rainfall patterns. When it did rain, the systems were there to harvest very good quantities of water. These ancient water-harvesting methods were part of larger integrated human and agricultural systems, which harvested natural rainfall to sustain productive human cultures.

Water supplies around the world are facing substantial problems in terms of shortages and contamination. Aquifer and river systems that once met demand are no longer doing so.

Some of these systems are badly polluted. Very large dam systems that became popular in the latter part of the 20th century are also increasingly problematic. Yearly evaporation on the Aswan Dam, in Egypt, is measured in cubic kilometres. Silt is a major concern, to say nothing of the effect dams have on local populations and natural ecological cycles.

At the beginning of the 21st century, water supplies are all-important. It is estimated that millions die all over the world because of water-related problems. It has also been estimated that with current global population and development trends, some 360,000 more people will need access to drinking water every day until the year 2015.

There is an increasing body of research to suggest that the methodologies behind ancient hydrological systems could be used to provide sustainable water resources to large numbers of people in what are quite arid areas of the world. Unfortunately, these ancient water systems are usually treated as mere ‘historical curiosities’. This view overlooks the fact they display excellent engineering and innovative hydrology techniques with regard to the delivery of water to human populations for agricultural and other purposes. Perhaps it is time to look again at the hydrological systems of the ancient world in regard to providing viable water solutions to communities in the drier regions of our planet.

Michael Kenneth Cowan is a freelance journalist and resident of the Crystal Waters ecovillage in Australia

This article first appeared in the Ecologist June 2007

 

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