Page 19 -

Information on Rivers
It has been noted that on average, the air distance from the beginning to the end of most

rivers is about three times less than their actual length. For rivers that flow in plain areas,
[1]
this number is very close to Pi; Einstein wrote an explanation of why this is so.[1]

Other types of rivers

Most rivers flow on the surface, however other rivers may flow underground in caves or
caverns. Such rivers can be found in karst regions with limestone geologic formations.

An intermittent river (or ephemeral river) flows occasionally and can be dry for several

years at a time. These rivers are found in regions with limited and highly variable rainfall.

Use of rivers

Man has been using rivers for navigation since the dawn of
civilization. Rivers provide the cheapest means of transport. In this
figure a country boat is seen plying over Hooghly River at Kolkata,

India.

Rivers have been used by man since the dawn of civilization as a source of water, for food,
for transport, as a defensive barrier, as a source of power to drive machinery, and as a
means of disposing of waste.

For thousands of years rivers have been used for navigation (The earliest evidence of

navigation is found in the Indus Valley Civilization, which existed in north-western India
around 3300 BC). Riverine navigation provides the cheapest means of transport and is still
used extensively on major rivers of the world like the Ganges, the Nile, the Mississippi, and
the Indus.

In some highly-forested countries like Scandinavia and Canada, lumberjacks use the river to
float felled trees downstream to lumber camps for further processing, saving much effort

and cost by transporting the huge heavy logs by natural means.

Rivers have been a source of food since pre-history. Apart from being a rich source of fish,
rivers indirectly aid cultivation by supplying water for the crops. Rivers sustain their own
food chain. They are a major source of fresh water, hence, it is no surprise to find most of
the major cities of the world situated on the banks of rivers. Rivers also provide an easy (if

unsanitary) means of disposing of waste.

The rocks and gravel generated and moved by rivers have been greatly used in construction.
In more recent generations, the beauty of rivers and their wider habitats has contributed
greatly to tourist income from areas well endowed with attractive riverine scenery.

(God's Amazing Landscapes) 16