The Rivers of the World

"All the rivers run to the sea, but the sea is not full; To the place from where the rivers flow, there they flow again."

Ecclesiastes 1:7

Rivers, long or short, wide or narrow, limpid or muddy, are a vital part of the Earth's delicately balanced water system that also takes in the seas and oceans, lakes, clouds and rain. If water is the life-blood of planet Earth, then rivers are the arteries and veins. The rivers carry rainwater collected from mountains and natural basins. These are called watersheds and are the source or point of origin of almost all rivers.

The rivers then run to their mouths, the point at which they reach the sea, a lake or a bigger river. Rivers that feed into bigger rivers are called 'tributaries'. By definition, rivers are natural, not man-made like canals. And that's about as precise as the definition gets: a natural waterway, coming from a source and arriving at its mouth. If this poses the question – when is a stream too big to be called a stream and, therefore, becomes a river? – there is no facile answer. It just depends on what local people tend to call it.

However, we do have some hard facts. Let's establish, first of all, that the Nile, in Africa, is the longest river in the world, starting from its source in Uganda and debouching into the Mediterranean, several thousand kilometres to the north. The next longest is the Amazon in South America followed by the Yangtze in China. But, in all fairness, length is not the only criterion by which we can judge rivers. We can also talk about sheer volume of water.

This is like asking not 'who is the tallest person in the room?' but 'who is the largest?' The Amazon wins this one hands down. It debouches so much river water into the Atlantic that there is fresh water, not salt, out of sight of the coast, kilometres out to sea. The second biggest by volume is the Ganges in India; and then the Congo in Africa. The Ganges, by the way, is also an example of a sacred river; in this case for Hindus. Its waters are considered spiritually cleansing. Unfortunately, they are not physically cleansing as the Ganges is, these days, a very polluted and insanitary river.

There are many other examples of sacred rivers but to give just one more – the River Jordan in the Middle East – a river of enormous importance to Christians for baptism ceremonies and, these days, the subject of dispute between Israel and several neighbouring countries, all wanting its waters for their agriculture.

And it is its connection to agriculture, especially for irrigation, that has made rivers so central to human civilisation from its beginnings eight to ten thousand years ago. Clearly, growing crops next to or very close to a river guarantees well watered and well drained land even if the rains fail. Furthermore, rivers often deposit rich mud (called 'silt') along their banks, washed down from further upstream.

The silt makes highly productive soil which explains why a very narrow strip of farmland on either bank of the Nile allows Egyptian farmers to produce very large crops that feed the tens of millions who live in and around the capital, Cairo.

And, then, there's another advantage to rivers. When you want to ship your crops or animals to market, and the bigger market will usually be downstream, you can put everything on a boat and just float it down to the nearest town or city, no fuel or hard work needed. Naturally, this kind of transport can be used by anybody, not just farmers going to market but tradesmen and their goods, government officials or private travellers. Rivers were the first catalyst to long-distance trade and communication and were a little safer than the roads; though river pirates are not unheard of, even today.

So, rivers make for great transport routes if you're going their way; but, what if you don't want to follow the course of the river but just to cross it? Originally, there were two ways, fords or ferries. Fords are the natural shallow points in a river, where it might be low and slow enough for people and animals to wade across. Often, local people would improve a ford by putting stones into it to make it even shallower.

Ferries were just little boats, frequently attached to both banks by a rope or chain tied to a tree on either side. Neither method was ideal and, so, the art of bridge building developed. At first, it was hard to make strong, long bridges that would allow a heavy cart to cross safely, so towns were situated a long way up the river from the mouth but, as techniques improved in the last thousand years or so, cities started to appear very close to the sea. In the case of Budapest, the capital of Hungary, the building of good bridges across the River Danube united the formerly separate towns of Buda on one bank and Pest on the other.

And it is this difficulty in crossing them that makes rivers good natural barriers. This is why rivers often mark the border between two countries, like the Rio Grande that marks the border between Mexico and the U.S.A. Even as recently as the Second World War, whole armies could be delayed for weeks and even months if the bridges were down and the enemy was waiting, armed and ready on the other bank.

Finally, 'the river' has always been a strong theme and symbol in art and literature, with Mark Twain's 'Huckleberry Finn', set on the Mississippi River in the Southern U.S.A., and Joseph Conrad's 'Heart of Darkness', set on the Congo in central Africa, being just two examples. The river often represents change and the passage of time. But, more than anything, it represents 'life' as it travels from its source or 'birth' to its end and 'burial' in the sea only to flow again through the clouds to its place of origin.

An eternal cycle.