Rivers
A river is a moving body of water that flows from its source on high ground, across land, and then into another body of water, which could be a lake, the sea, an ocean or even another river.
A river flows along a channel with banks on both sides and a bed at the bottom. If there is lots of rainfall, or snow or ice melting, rivers often rise over the top of their banks and begin to flow onto the floodplains at either side.
To learn more please access the resources below.
How are rivers formed?
Rivers usually begin in upland areas, when rain falls on high ground and begins to flow downhill. They always flow downhill because of gravity.
They then flow across the land - meandering - or going around objects such as hills or large rocks. They flow until they reach another body of water. As rivers flow, they erode - or wear away - the land.
Over a long period of time rivers create valleys, or gorges and canyons if the river is strong enough to erode rock. They take the sediment - bits of soil and rock - and carry it along with them.
Small rivers are usually known as streams, brooks or creeks. If they flow from underground they are called springs.
River Resources
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Planet Earth - Fresh Water |
| The episode follows the descent of the planet's mightiest rivers from their mountain sources to the sea. | |
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BBC Teach - Zoom In, Zoom Out - Rivers |
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National Geographic Kids - Rivers - The Nile |
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BBC Teach - Rivers |
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BBC Teach - Living next to rivers - Belfast and Pune |
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Class Clips - Tongland Power Station and the River Dee |
Key Vocabulary
River: a body of water that flows toward the sea
Main channel: the main river which flows and drains the surrounding area
River catchment: all the rivers, streams and lakes within one area which drain through the same river mouth into the sea
Source: where a river starts in higher ground, usually a spring, although some rivers flow from lakes or reservoirs (and also glaciers)
River mouth: the end of a river where it meets the coast and drains into the sea, or sometimes a lake
Downstream: the direction a river flow from its source to its mouth, from highland to lowland area
Upstream: Moving against the flow of a river from low land to higher land, towards its source
Upper, middle and lower courses: the three main sections of a river:
- Upper course: characterised by narrow channels and steep gradients, often with rapids, waterfalls and gorges. Upper courses are typically in highland areas and have steep sided ‘v-shaped’ valleys with interlocking spurs. Erosion is vertical, deepening the channel.
- Middle course: characterised by more gentle gradients and a wider channel, which is deeper and meanders across a wide valley. Erosion is lateral, particularly on the outer edges of meanders, which will cut into the surrounding area, whilst deposition occurs in the inside of the meander loops.
- Lower course: characterised by deep and wider channels located within a flat landscape. Flood plains are typically found in lower courses. As a river floods it may also deposit material on the river banks forming raised levees. Where a river drains into the sea it may deposit materials to form a delta.
Tributary: a smaller river, or stream, which flows into a larger river
Confluence: where a tributary meets another river
Meander: a natural bend in the river
Flood Plain: the area onto which a river floods, usually in the lower course
Erosion: the break-up of material from the river bed or the river banks
Transportation: the movement of materials, such as pebbles or silt downstream
Deposition: when a river stops transporting materials and the materials are ‘dropped’ either in the river bed, at the inside of a bend, on the riverbank or flood plain during a flood, or in a delta at its mouth.
Delta: an area of new land formed at the mouth of a river when material (sometimes called sediment) is deposited. Deltas are usually found when a river flows into the sea or an ocean, and can also be found when a river flows into a lake or reservoir.
Estuary: a coastal body of water, into which rivers or streams flow which is influenced by both fresh water from the rivers and saline water from the open sea.
Fifteen Facts about Rivers
1) The Nile River is widely accepted as the world’s longest river. Found in north Africa, it flows through 11 different countries and stretches a whopping 6,695km – that’s as long as 65,000 football pitches!
2) The Amazon River comes in a close second, winding a huge 6,840km through the mountains and rainforests of South America!
3) In 2007 a man named Martin Strel swam the entire length of the Amazon river! To complete his amazing jungle journey, Martin swam ten hours a day for 66 days!
4) The world’s deepest river? That’s the Congo River in Central Africa. Whilst its true depth remains a mystery, scientists believe the waters run at least 230m deep in parts – deep enough to submerge London’s famous clocktower, known as Big Ben, 2.5 times on top of each other!
5) As rivers flow their course across the land, they form lots of fascinating geographic features, such as amazing mountain valleys, canyons, lakes and, of course, wonderful waterfalls!
6) Some record-breaking waterfalls formed by our planet’s rivers include…
Angel Falls, Venezuela – the world’s highest waterfall at a staggering 979m tall!
Khone Falls, Laos – the widest waterfall, measuring an incredible 10,783m!
Inga Falls, Democratic Republic of the Congo – the world’s largest waterfall, if we’re talking about the amount of water. Every second, 25,768 cubic metres plunges down the fall – that’s more than ten Olympic swimming pools!
7) Rivers can be all kinds of colours – not just blue, clear or muddy brown as you might expect! In ‘blackwater rivers’, found in swamps and wetlands, the waters look like strong black tea. And in Colombia, the aquatic plants of Caño Cristales – known as the ‘River of Five Colours‘ – make the waters flow with bright blue, red, black, yellow and green!
8) Not all rivers flow overland – ‘subterranean rivers‘ run secretly beneath the surface! This is sometimes because of human engineering. Ever heard of London’s ‘lost rivers‘? These are streams of the River Thames and River Lea that were built over as the city grew.
9) Subterranean rivers can also exist naturally. In the Philippines for example, the Puerto Princesa Underground River flows beneath a mountain for five miles, before finally emptying into the South China Sea.
10) It’s not just rivers themselves which are fascinating – it’s the wonderful wildlife that lives in them, too! Rivers provide a home for all kinds of creatures, including insects, amphibians, birds, reptiles, mammals and over 10,000 species of fish!
11) Some of the most fascinating river creatures include Amazon river dolphins (which have pink skin!), electric eels (which stun prey and predators with powerful electric shocks!), freshwater stingrays (which can grow to an enormous 5 metres!) and freshwater turtles, which have been around for 200 million years!
12) Rivers and lakes are a vital source of freshwater for life on Earth. But did you know they hold less than 1% of the world’s water? Most (over 99%, in fact) is in the salty ocean or frozen in our polar ice caps. That’s why it’s super important that we protect our rivers and look after the freshwater our planet provides.
13) Sadly, our rivers and waterways are being polluted by chemicals, sewage and household waste, which can cause serious harm to animals – and humans, too. In fact, an estimated 300-400 million tonnes of waste is thought to pollute our rivers and seas every year!
14) The good news is that people around the world are working hard to keep our rivers and fresh water supplies clean and safe. And you can help, too! Be sure to reuse and recycle whenever you can, and bin rubbish responsibly! And you can help save water, too – be sure to turn off the tap when brushing your teeth, and why not opt for a short shower over a long bath?
15) Did you know there’s a day dedicated to our planet’s wonderful waterways? Every September, millions of people from more than 70 countries celebrate World Rivers Day. This global event raises awareness of the importance of rivers and how we can best protect them for years to come!
Test Your Knowledge
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National Geographic Kids - Rivers Quiz |
| Dive into our wet and wild rivers quiz… |