river

Do you want to learn about rivers? Let's get started. 

Learning Objectives

• What is river? 
• Parts of a river
• Formation of river
• Uses of river
• Some major rivers of the world

What is river? 

A river is a natural water stream flowing through a channel over land. Rivers only hold a small amount of the Earth’s water, but they have always been vital to human life, carrying fresh water to people and animals all over the world. And they’re super-powerful forces of nature, too - shaping the land as they flow. 

A river begins on high ground, hills, or mountains and flows downhill because of gravity. It begins as a small stream and gets bigger the farther it flows. Some rivers flow year-round while others flow only during certain seasons or when there has been a lot of rain.  

The passage where the river flows is called the river bed, and the earth on each side is called a river bank.

The current describe how fast and powerful the river is. Rivers that have a lot of water and a steep decline can be very fast. 

Parts of a river

No matter how different our rivers are, all rivers share some basic parts.

1. Source or headwaters - All rivers have a starting point where the water begins its flow. This source is called headwater. The headwater can come from rainfall or snowmelt in mountains, but it can also bubble up from groundwater as springs or a lake where lots of water from small streams gathers when it rains or snows. For example, the source of the River Nile is Lake Victoria in Burundi, and the source of the River Thames is a spring. 
2. Tributaries - A tributary is a river or stream that feeds into another river rather than ending in a lake, pond, or ocean. If a river is large, there's a good chance that much of its water comes from tributaries. 
3. River Channel - As the river flows, it carves the landscape giving it a certain shape. This shape depends on how much water has been flowing in it, what kind of rocks, soil, and vegetation are present, and for how long it is flowing. River channels can be straight, meandering, and braided. 
4. Riverbank - This land next to the river, including the trees and other vegetation growing streamside, is often known as the "riparian zone." This area provides important habitat for birds and other wildlife. 
5. Mouth or Delta - It is the end of the river where the river water empties into a larger body of water, such as a lake or ocean. At a delta, the land flattens out and the water loses speed, spreading into a fan shape.

How rivers flow?

The tiny trickles of water from rainfall, melting snow or ice, and underground springs on the high ground run downhill. On the way, they combine with other trickles and may be called a stream, a brook, or a creek. The creek runs into a river. 

In its upper course, the river flows fast, cutting through the land and picking up soil and gravel. As river water flows, it can erode the rocks and land around them. This can create canyons, valleys, and gorges. This takes a long time to happen though. This is how the Colorado River formed the Grand Canyon in the United States.

In its middle course, the river flows down and gets larger. The pace of the river begins to slow down. Sand, soil, and gravel sink to the bottom and, over a period of time, may get deposited to form islands. 

In its lower course, the river becomes very gentle and slow. While some solid material gets dropped on the way, some material is carried all the way to the mouth where the river enters the sea and may build up to form a piece of land called a delta, 

Formation of rivers

The below picture shows the River Nile in Egypt

In mountainous and hilly areas, rainwater flows and concentrates in lower areas, which fill up to form lakes. Afterward, the first channels are formed, quickly eroding through the land with the strength of the flow and the sediment carried by the water. A young river forms, which gradually erodes a deeper channel. Finally, when the river flows through lowlands, the channel will erode the outer banks of bends, depositing sediment and generating a flood plain until it reaches its mouth.

The water that flows in rivers is fresh, meaning that it contains less than one percent salt.

Rivers serve many uses

When we say "river of life," it has a lot of value. Ever since life began, rivers have been essential to all life on earth. Plants and animals grow and congregate around rivers simply because water is so essential to all life. It might seem that rivers happen to run through many cities in the world, but it is not that the rivers go through the city, but rather that the city was built and grew up around the river. Humans divert rivers for flood control, irrigation, power generation, public, and municipal uses, and even waste disposal. 

Rivers can flood if there is a lot of rainfall

Rivers can sometimes flood. This is usually because of a high amount of rainfall. Sometimes the rivers can’t cope with a large amount of water and the banks will burst. The water will then overflow out of the river and will sometimes cause devastation in people’s houses and towns.

Wildlife in rivers

Rivers are often home to a wide variety of species from insects to amphibians, reptiles, fish, birds and even mammals. Turtles, ducks, otters, crocodiles, catfish, dragonflies, and crabs can be found in rivers all around the world, and the Amazon river is even home to the rare and pink, freshwater dolphin. An extraordinary number of different fish species can also be found in rivers and streams all over the world. 

You can find some freshwater plant species growing along the water's edge, such as cattails. Other plants grow along the surface of the water, such as water lilies and duckweed. Fish like to hide in the safety of the shadows created by these plants.

Here are some fun facts about rivers

• The longest river in the world is the River Nile. It can be found in Egypt, north Africa. It flows through 11 different countries and stretches a whopping 6650 km or 4132 miles!
• The Amazon River in South America carries the most water.
• You can get very short rivers too! In fact, the shortest river is only 201 feet which is 61 meters! It’s called the Roe River and is located in Montana, USA.
• Rivers can be all kinds of colors – not just blue, clear, or muddy brown as you might expect! The blackwater rivers found in swamps and wetlands appear like strong black tea. The Caño Cristales river in La Macarena, Colombia is dubbed the “River of Five Colors” and “Liquid Rainbow” because of the many colors you can see below the clear waters. Bright greens, yellows, reds, and purples appear to be flowing down the river depending on the light and water conditions. According to local legend, it escaped paradise to flow through the Earth.
• Rivers change over time. Floods may make them larger, droughts cause them to shrink or dry up. People and animals change them too.