Rivers are water that is a large stream that is made up of freshwater.  A river can be fast or slow and can change a lot over time.

Where a river flows is called the riverbed and the ground on each side of the river is called a river bank.

Daugava river.

Parts of a River

There are different parts of a river such as:

  • Head-This is the part of the river that is where the river starts.
  • Mature-This is the middle part of the river.  This is where the river gets its shape and where much of the water runs fast.
  • Mouth-This is the part of the river where the river ends.

Some rivers are known for having waterfalls and rapids.  Since a river sometimes starts on a mountain, it is very easy to find a waterfall.


A spring is different than a river because the water flows from under the ground.  A spring can be the source of a river.

Samur River


A current tells us how fast water is flowing and how powerful the river is.  Some rivers have a steep decline, and this will cause the river to go faster.  Rivers that are flat or have an incline will go slower.


Some rivers have what is called an estuary.  An estuary is when the mouth of the river is wide and acts like a funnel.

Sometimes in an estuary, saltwater and freshwater can mix.

The Loboc River

There are many animals that live by an estuary such as:

  • Clams
  • Mollusks
  • Fish

The mouth of the river can be different for each river depending on what flows into the river.


The delta is a place where a stream gets broken and shapes like a triangle.  These are places that are not good for towns but are good for wildlife.  Some wildlife that is found around deltas are:

  • Fish
  • Birds

Not all rivers have deltas.

Underground Rivers

There are also rivers that flow underground.  Many of these rivers flow through caves.

Underground rivers form when there are cracks in the rocks above and water runs down the crack and forms a river.  This happens when there is a lot of rain or snow.

Most underground rivers are slow flowing, but some can have rapids after a heavy rain, sometimes these rivers flow through the mouth of a cave and meet with a regular river.

Do Rivers Change?

All rivers can change depending on the weather and depending on other things.  Sometimes, if there is a lot of water flowing like from a flood, the river will get stronger and bigger.  If there is a drought, the river will be lower and may even dry completely up.

Rivers can be changed by people and animals.  Animals and people can build dams that stop water from flowing.  Some people build flood walls to help keep the water in a certain spot in case there is a lot of rain.

People build flood walls so that the water will not flood their homes and businesses.


Rivers can be made from erosion and they can cause erosion.  When there is a lot of water that flows in one area, it can carve out the rock and ground and cause a river to be formed.  When the water flows through the river, there is always erosion happening.

Erosion can cause the river to get bigger and wider.  Rivers can even carve out big giant landscapes.  One example of this is the Grand Canyon.  The Grand Canyon was created from a river that flowed through the area constantly.

How Do Most Rivers Form?

Most rivers are made form snow or glaciers that have melted from the top of a mountain.  When this happens, the water flows downhill and that is where erosion happens.  This can take millions of years for a river to be formed.

Rivers can also be formed when more than one stream forms together.  When there is more than one stream, the smaller one is called a tributary.

It takes a lot of tributaries to make one river.

Sometimes, a river will even form because of a lake.  This can happen because of water that flows in one area for a long time.

Where Do Rivers End?

A river is considered at its ending point when it flows into a larger body of water.  This is called the mouth of the river.

Characteristics of Rivers

There are no true characteristics of rivers because they can be big, and they can be small.  They can get water from rain, snow or ice and they can get water from ponds or lakes.

The only rule of a river is that it has to have a water source, and something has to flow from it.

A river is a freshwater biome.

Freshwater Biome

A freshwater biome is a biome that has water that does not have a lot of salt in the water.  There are three different types of freshwater biomes, wetlands, ponds and lakes and streams and rivers.


Like the ponds and lakes, the streams and river also have an ecosystem and it is called the lotic.  This means that the water continuously flows and moves and rotates.

A stream and a river can come in different sizes, from a super small stream that just barely trickles down, to a river that can be miles and miles long.

There are a few things that decide if a freshwater biome is a stream and a river and this includes:

  • Chemistry
  • Flow
  • Light


The chemistry decides what kind of nutrients and soil are found in the river or stream.


The flow is important because it tells how strong the water will move and this can affect the way that animals and plants live.


The light helps plants that are closer to the sunlight to be able to grow because of photosynthesis.


The temperature impacts how plants and animals live in that area.

Animals of the River

Animals that live around the river are usually:

  • Fish
  • Snakes
  • Crocodiles
  • Beavers

The plants are usually found in areas where the water flows slower and they include:

  • Birch
  • Willow trees
  • Grasses

Why Are Rivers Important?

Rivers are important because they have a lot of life that lives by them and in them but they are also important because they can give people drinking water when there is a drought or other problems with getting water.

Rivers also help to keep areas from flooding because water that comes from rain and other areas can run into the river.  The river will eventually drain into a lake, ocean or even a bigger river.

Rivers also give people:

  • Food
  • Energy
  • Transportation
  • Drinking Water
  • Water for crops
  • To run machinery
  • To give water for factories
  • To give water to cattle
  • To give products such as clay
  • For swimming and other fun activities
  • Transportation for boats.


The upstream of a river is when the water is coming from something like a mountain.


A downstream is when the water flows to get to its end.

Longest Rivers of the World

Some of the longest rivers of the world include:

  • The Nile-This is the longest river and is located in Africa.
  • The Amazon-The Amazon is found in South America.
  • Yangzi-This river is located in China.
  • Mississippi and the Missouri Rivers-These rivers are found in the United States and together they make one of the longest rivers in the world.

Why Are World Rivers Important?

World rivers are important because they are important for people to be able to travel on and for trade.  Most rivers have a big history and people have used rivers for hundreds of years to be able to trade and survive.

How Are Rivers Harmed?

People can harm rivers by pollution.  Pollution can cause rivers to not be safe to drink and it can cause animals that live in the water to die form the pollution.

Since rivers mostly come from rain or snow, the water is safe to drink unless it is polluted.

More Facts About Rivers:

  • The longest river, the Amazon River, is found in Africa.
  • More than 70 rivers in the world are more than 1,000 miles long.
  • People think that rivers flow south but some of the rivers also flow north.
  • There are 3.5 million miles of river that are found in the United States.
  • Most big cities are located close to rivers.
  • Rivers sometimes turn into canals.

What Did You Learn?

  • What is a river?
    A river is water that runs through an area on the ground.
  • Does gravity play a part in a river?
    Yes.  Gravity helps a river flow.  If a river starts on top of a mountain, it will flow down because of gravity.
  • Do animals live in the river?
    There are different types of rivers and most rivers have some type of animal.  Some rivers have different animals than other rivers.
  • Are rivers important?
    Rivers are important because they help people to be able to travel, they give water to drink for people and animals, they help run machines and help with factories and more.
  • Are rivers different?
    Rivers are all different and there is not specific thing that a river has to do except to have a water source and to flow.