When a lot of rain falls in a short time, the ground can’t always absorb it quickly enough. This means that lots more water than normal flows into the rivers. If there is more water than the river can carry away to the sea, it bursts over its banks and floods the land around it. This is called a ‘flash flood’ because it happens so quickly.
There aren’t always many safe places to cross a river on foot, and building bridges was hard for people before they had modern machines. Anyone going on a journey would have to cross a river at the same place as lots of other people. Towns would often grow up around these places so that travellers could find a place to sleep or trade goods with each other.
The mouth of a river also used to be a very good place to build a town. Large boats that cross the sea to other countries can sail into the mouth of the river to unload their cargo and to load local produce to take elsewhere. Small boats can sail up and down the river taking goods to and from the towns that are further inland.
Lots of towns are named after river crossings or the rivers that flow through them. Oxford is named after a ford where people used to take their oxen across the river Thames. Stourbridge is a town in the West Midlands where there is an old bridge over the river Stour. Dartmouth in Devon is town at the mouth of the river Dart. How many towns in your area are named after rivers or river crossings?
The Welsh word for a river mouth is ‘aber’. Many Welsh towns are named after the rivers that they are on, just as they are in England. Aberystwyth is town at the mouth (aber) of the river Ystwyth.
The faster a river flows, the more erosion it causes in the soil and rocks around it. Over millions of years streams and rivers will remove more and more material from the area around them and cut bigger and bigger paths for themselves. This is how valleys are created. Even quite small streams can create big valleys over a long time.
When the slope that rivers are flowing down stops being so steep, rivers slow down and instead of rushing down the straightest path through the valley, they often start to curve and bend. These curves are called meanders.
Erosion on the bends of the meanders means that they are slowly changing shape and that path the river takes will gradually change. Sometimes the erosion will cut a straight path for the river to take and leave what used to be a bend isolated from the river. This is called an ‘ox-bow lake’.
Sometimes to make it easier to for boats to travel up and down rivers, people change the way that the river flows. If part of a river is very bendy, they might dig a straighter channel for the river to flow down so that the boats don’t have to make tight turns. Sometimes they make the river wider or make it deeper so that bigger boats can travel on it. When the river is too steep and flows to fast, they might put in locks to make it safer for the boats to travel.
Rivers have also been used for a long time to help people work equipment. People would build mills to grind corn and grain near to rivers so that they could use a water wheel to work the mill. The bottom of the wheel would be put into the water, and when the water turned the wheel, the wheel would make the equipment in the mill turn and grind up the grain.
Today, instead of using a wheel to operate equipment, we build big dams across the rivers and use the force of the water to turn turbines and generate electricity to power our machines. We call this hydro-electricity because it is generated from water.
Words to know:
Bank – The riverbank is the land at the side of the river.
Basin – Rainwater that falls on hills flows down the side of the hills into rivers. A river basin the group of hills, valleys and lakes that water flows into the river from.
Bed – The bed is the bottom of a river. A riverbed can be made of sand, rocks or mud depending on the river.
Canal – A man-made waterway that is used so that boats can transport goods across bits of the country where there are no rivers they can use.
Current – The strength and speed of the river. Water always flows downhill; the steeper the ground is, the stronger the current will be.
Delta – A wide muddy or sandy area where some rivers meet the sea. The river slows down and drops all the sediments it was carrying.
Downstream – The direction that the water flows, downhill towards the sea
Fresh water – Rainwater that falls from the sky has no salt in it. We call this fresh water.
Erosion – When a river flows fast it damages the riverbanks and washes bits of them downstream. This makes the river wider.
Estuary – Where a river reaches the ocean and the river and ocean mix. Estuaries are normally wide and flat.
Floodplain – The flat area around a river that often gets flooded when the level of water in the river is high.
Mouth – The end of a river where it flows into the sea, another river or a lake.
Salt water – The water in the sea is full of salt, so ‘salt water’ refers to water in seas and oceans.
Silt – Small bits of dirt or sand that are carried along by a river.
Source – The start of a river is its source. This could be a spring on a hillside, a lake, or a bog or marsh. A river may have more than one source.
Stream – A small river
Tidal river – At the end of a river, near the ocean, water from the sea flows up the river when the tide comes in. This bit of the river is called ‘tidal’.
Tributary – A smaller river or stream that joins a big river is called a tributary.
Upstream – The opposite direction to the way the water in a river flows
Watershed – Water flows down the side of hills into rivers. But, water that lands on opposite sides of the same hill might flow into different rivers. The watershed is the boundary between two river basins.
River Thames Fact File
Length: 346 km (215 miles)
Source: Thames Head, Gloucestershire (England)
Mouth: Thames Estuary (North Sea)
Other Facts About The River Thames
- The River Thames is the second longest river in the UK.
- It is the most well-known of Britain’s rivers because it flows through central London. It also flows through (or really close by) some other important towns and cities in England, such as: Richmond, Kingston upon Thames, Windsor, Henley-on-Thames, Oxford and Reading.
- The Thames is tidal when it flows through London.
- More than 80 islands are contained in the River Thames. These include: the Isle of Sheppey, Canvey Island and Rose Isle.
- The Celts referred to the Thames as Tamesas (or Tamesis), which meant ‘dark’.
- About two thirds of London’s drinking water comes from the Thames.
- The River Thames has several tributaries, including: the River Churn, Windrush, Cherwell, Thame, Loddon and Mole. Several rivers also join the Thames after it has become tidal. These include: the River Brent, Effra, Westbourne and Fleet.
- The Thames becomes tidal below Teddington Lock. This is just over 50 miles from the Thames Estuary (and the river’s mouth).
- The Thames is the home to many different types of creatures. Lots of birds can be found at different points along the course of the Thames from source to mouth (such as herons, moorhens, grebes, kingfishers and coots). The Thames supports lots of different fish species too, including: trout, chub, roach, pike and many more.
- John Burns (a Battersea MP) famously described the Thames as ‘liquid history’. He meant that River Thames was responsible for supporting settlements upon its banks throught British history, from Neolithic times to today. The Thames has witnessed the birth of London and many of the key events in Britain’s history.
- The Thames has been bridged more than 200 times and it has been tunneled under more than 15 times. Many of today’s bridges have been built on the site of much earlier crossing points.
Check out our other fact files on important rivers by clicking here or discover more London facts by visiting our London resources page.