PART I
THE BINDING OF THE NILE
CHAPTER I
THE NILE
Far back in the world’s history a fracture of the earth’s crust took place in the region which is now Egypt, and the sea filled the valley as far as a point not much north of Assouan. Into this fiord ran several rivers from the high ground east and west, bearing down with them heaps of detritus, and forming small deltas like the plain of Kom-Ombos. On the sea-bottom were laid down deposits of sand and gravel, and then the land began to rise. Meantime the volcanic movements of East Central Africa had shaped the country into its present configuration, and the rivers which drained from the great lakes and swamps of the south, and those which flowed down from the high plateau on the east, combining their waters somewhere about Khartoum, pushed their marvellous course northwards, and began the creation of the fertile soil of Egypt. From this time onwards the climatic conditions must have continued very much what they are to-day. Changes, of course, there have been in the level of the land; but the sea-valley had become a river-valley, and year by year the annual flood increased the cultivable soil, and refreshed it with moisture, just as it would be doing to-day if left untrammelled by the devices of man.
Late in the history of the river-valley, but very early in the history of humanity, this favoured strip of country became the home of men, who doubtless cast their seed upon the slime left by the retreating waters, and reaped their crops long before the dawn of history. It is remarkable and characteristic of the conditions of the country that tradition ascribes to the earliest King of Egypt, Menes, the first King of the First Dynasty, the first attempts to regulate the flow of the river—in other words, the first scheme of irrigation proper.
If it were possible to divert the river from its course, and effectually to bar its way before it reached the boundaries of Egypt, what an appalling catastrophe would follow—no mere disaster, but absolute annihilation! On the coast lands of the Mediterranean a sparse population might still eke out a miserable existence by storing the scanty rainfall, but nowhere else. The very oases of the desert would be dried up, and in a short time the shifting sands of the Sahara would have overlaid the deposits in the river-valley, and buried out of sight even the ruins of the past. The waters of the Nile are, and ever have been, the sole giver of all life in Egypt.
Whoever finds himself in Cairo should lose no time in taking his stand upon the bridge, and in reflecting upon the history of the water that goes sliding and eddying beneath him, on the way to perform its last duties among the cotton-fields of the delta. Some of it has been travelling for three months from its sources beyond the Victoria Nyanza, itself over 1,100 metres[1] above sea-level. From the Victoria Nyanza it has passed down the Somerset Nile into the Albert Nyanza, thence a five days’ journey to Lado, past Duffile and the Fola Rapids. From Lado to Bor the fall is still rapid, but henceforward as far as Khartoum, some 1,000 miles, the stream is on a very feeble slope. Between Bor and the junction of the Ghazal River on the left bank is the region of the sudd, floating masses of compressed vegetation, which, if neglected entirely, block the course of the river. Here, too, are the wide and desolate marshes, inhabited by myriads of mosquitoes and that strange, melancholy bird, the whale-headed stork (Balæniceps rex).
The Ghazal River contributes very little to the flow of the Nile, owing to wide lagoons through which it passes, and which cause great evaporation. The river then passes sharply to the right, and sixty miles further on is joined by the Sobat from the eastern hills, which in flood brings down a volume equal to that of the Nile, but during summer contributes little or nothing. From the white sediment brought down by the Sobat the White Nile derives its name and colour. Hence it flows in a wide bed, a mile across on the average, 540 miles to its junction with the Blue Nile at Khartoum. Khartoum is still 1,800 miles from the sea, and 390 metres above it. Two hundred miles north of Khartoum, near to Berber, the Atbara River flows in, and hence the Nile pursues its solitary way through the desert until, after a circuitous bend round Dongola, it bursts through the rocky defiles of Nubia, and emerges at Assouan into Egypt proper. Of the distance between Khartoum and Assouan about 350 miles consist of so-called cataracts, during which the total drop is 200 metres; about 750 miles are ordinary channel, with a total drop of nearly 100 metres.
Of all the affluents of the Nile, the Blue Nile (assisted by its tributaries, the Rahad and the Dinder) and the Atbara have been of infinitely the greatest importance to Egypt in the past. Not only do their waters contribute the largest proportion of the annual flood, but also down them comes the rich volcanic detritus swept from the Abyssinian hills by the heavy summer rains, which composes the red-brown silt so dear to the Egyptian cultivator. To understand the system of irrigation in Egypt it is necessary to have a clear view of the amount of water derived from the different sources at different times of the year.
The great lakes and swamps of Uganda, acting as reservoirs, prevent any great differences in the discharge of water above Lado. At that place the low Nile discharge is about 500 cubic metres[2] per second; but, in spite of the Ghazal River and the Sobat, so great is the loss by diffusion in the marshes and by direct evaporation, that at Khartoum the discharge is no more than 300 cubic metres per second. At this time the Blue Nile is giving no more than 160 cubic metres per second at Khartoum, and the Atbara is not running at all. The loss between Khartoum and Assouan is about 50 cubic metres, and consequently the amount of water passing Assouan in May in an ordinary year is 410 cubic metres per second. This is the summer supply of Egypt.