Introduction

In this chapter a brief outline is given of the evolution of the River Nile. The river seems to have developed as a result of the interconnection of several independent basins and rivers. The Egyptian Nile is shown to have undergone great changes since it started excavating its channel in the late Miocene time. The shape and regimen of the extant river developed only about 10,000 years ago during the last wet phase which affected Africa after the retreat of the last glacial.

The shape of the modern Nile is a very recent development; it is but the last stage of a continuously evolving river which changed its face many times before it assumed its present configuration. The River Nile spans 5646 kilometres from Lake Victoria to the Mediterranean Sea (figure 1). The slope of the river shows marked changes passing through several gently sloping ‘landings’ which are connected by steeply-sloping rivers. Figure 2 is a longitudinal section of the river from the equatorial lakes to the sea. It shows five ‘landings’ which are from south to north: Lake Victoria, Lake Kioga and the stretches from Lake Albert to Nimule, from Juba to Khartoum and from Wadi Haifa to the Mediterranean. The stretches of the river which connect these ‘landings’ are extremely steep, obstructed by waterfalls and cataracts and youthful in appearance and age. Before the river assumed its present-day course, these different landings' seem to have formed independent basins which were disconnected.