What Is "The Riddle Of The Nile"?

Maybe you did not even know the Nile River had a "riddle". Well, it is something that has puzzled people for thousands of years, and it has to do with a very curious event.
Every year in Egypt, the Nile River starts to rise in July and continues to rise until October, when its level is about 7.5 meters above the level in May. During the high-water season, the Nile spills over its banks and deposits fertile silt on the fields along its course.

What makes this rising of the river mysterious is that there is practically no rainfall in Egypt! So for hundreds of years people have wondered what makes the Nile rise so regularly each year. This "riddle of the Nile" was not solved until late in the nineteenth century.The Nile is the longest river in the world. It flows over 4,000 miles from south to north in the north-eastern part of Africa, mainly in the Sudan and Egypt. The yearly flooding of the Nile has made its valley a fertile ribbon in a hot, dry, barren wasteland, and people have lived here for thousands of years.

There are two great principal sources of the River Nile—the White Nile and the Blue Nile. The White Nile has its origin at Lake Victoria in Uganda. It has a fairly even flow throughout the year, so it cannot cause the annual rise of the Nile River. During April and May, when the water in the lower Nile is at its lowest, 85 per cent of the water is coming from the White Nile.

But what about the Blue Nile? It rises in Ethiopia. In the Ethiopian Mountains there are heavy rains and melting snows. And when these come down every year, they cause the Nile River to rise and overflow. And that is the answer to "the riddle of the Nile"!