Nile is running short of black gold

ONLY one of the seven wonders of the ancient world survives. The pyramids of Giza, just outside Cairo, have been standing for 4,600 years.

Khufu’s pyramid, the largest, is 145 metres high, 230 metres square at the base and consists of 2.3 million blocks of limestone, each weighing, on average, 2.5 tonnes. The weight of the enormous pile is about 6,000,000 tonnes.

The river Nile is about 11 kilometres away from the pyramids but, in Khufu’s day, it would have been much closer. Over 900 kilometres upstream of Giza, on this the longest river on Earth, lies one of the wonders of the modern world, the Aswan High Dam. It is not much of a spectacle and, at 118 metres, not as high as Khufu’s pyramid but it contains 18 times as much material. Over 3.6 kilometres long, its construction created the world’s largest artificial body of water, Lake Nasser, named after the leader whose great project this was. Completed in 1971, 451 men died in accidents during its construction.

The old name for Egypt was “Kemet,” which means “the black land.” In the month of June each year, the level of the Nile begins to rise. In the old days, the land was inundated and covered in black silt, carried down by the river from the uplands of Ethiopia, Uganda and the Sudan. The rich silt fertilised the Nile Valley, enabling crops to be grown in abundance. The annual inundation has been, and remains, the life-blood of the great linear oasis in the desert, which is Egypt.

But there were problems with the annual flood, even in ancient times. In some years, the rains failed to arrive. In others, too much rain fell, causing devastating floods in the lower Nile. Drought or floods were equally disastrous for Egypt’s harvest. According to the Book of Genesis, Pharaoh dreamt that seven lean cows ate seven fat ones. Joseph saw this as a prediction of famine, a warning that the harvest would fail for seven years. In response to Joseph’s suggestion, Pharaoh stored food during the good years to tide the country over the subsequent bad ones.

The Aswan Dam does the same, not with wheat but with water; the dam enables the level of the Nile to be controlled, independently of the annual rains. The economic benefits for Egypt have been enormous. The demand for water can now be met and the amount of cultivable land has increased by 30%. The dam provides electricity, about 2,500 million watts of it, half as much power as Ireland uses at peak; Ardnacrusha hydroelectric station, harnessing the power of the Shannon, generates a mere 84 million watts.

But tinkering with the great river has led to problems. The building of the dam has produced unwanted side-effects and the chickens are coming home to roost. The main problem concerns the famous silt. This black gold, so vital to Egypt’s farmers, is now in short supply. When the river reaches Lake Nasser, the flow ceases and the particles suspended in the water sink to the bottom. The lowlands below the dam are deprived of their annual top-up of nutrients and Egyptian agriculture depends more and more on massive applications of artificial fertiliser. The lands behind the levees are becoming increasingly salty and radical action will be needed to ameliorate the situation. It may be possible to extract silt from the bottom of the lake and transport it down to the lowlands. It’s a costly option and no decision on it has yet been taken.

The lake, almost 500 kilometres long and up to 75 metres deep, now has a nutrient-rich bed, among the chief beneficiaries of which are fish. There are over 190 species in the great river which drains one fifth of the entire African continent. The populations are thriving and some fish have grown to an enormous size. During three days sailing on the lake, last month, I saw no giants, but Nile perch, I was told, can weigh twice as much as an average-sized man. There is also a huge cat-fish. The lake equivalent of a deep-sea angling industry is developing. The fish downstream of the dam have fared less well and the decline in the fish stocks of the delta, at the river’s mouth, has been catastrophic.

Other wild creatures have been affected by the massive change in their habitat. Crocodiles and hippos were common around Aswan in the 19th Century. Crocs are still seen occasionally above the dam and locals approach visitors carrying small ones, their jaws taped together, as props for photographs. You will have to travel upstream into the Sudan to encounter a hippo.

Global warming is also affecting the Aswan project. Less water has flowed into Lake Nasser in recent years. The levels are lower now than they were a decade ago, to such an extent that there is insufficient water to drive all of the turbines in the power station. Of course, climate change may not be entirely to blame for the shortages. Eight countries exploit the Nile and the dam project required a treaty to cover the sharing of its water. New irrigation systems or increased water consumption upstream, which in theory must be approved internationally, reduce the quantity of water reaching Egypt. There have been rows with the neighbours in the past and even threats of military intervention if participants fail to live up to their agreements.