BC's rivers are as diverse as the landscape that they run through. Some are small, and meander slowly to their destinations, others are huger, fast and rush along. Here are some features of rivers that you need to learn about.
What is a River?
What is a river? We all think of a river as a wide strip of water, cutting its way through snowy hills and dense forests, as it winds its way downward toward the ocean? A river is certainly that, but it is much, much more! And it is constantly changing - with the weather and the seasons. It provides habitat for many, many plants and animals. It is a source of food for animals, fish and birds - as well as people. It is a nursery for insects and fish, and even some mammals.
Rivers and their smaller "cousins" streams and creeks are complex ecosystems that take part in the cycle of life that is our planet.
Where Does the Water Come From?
Have you ever wondered where the water comes from that is flowing in the river near you? There are three main sources for this water - rain or snow (precipitation), ground water (precipitation that has been stored in the ground for a long time) and melting glaciers. Water that falls as rain can either flow across the top of the ground (in streams and creeks) or soak into the ground and flow in underground channels. Eventually most of this water will join with a larger river or stream.
Food for thought . . . Some of the water that falls will be used by plants or animals, or evaporate. What time of year do you think that this most affects the water in a river?
What is a Watershed?
A watershed is an area of land that drains all the water into one main river. This draining process moves water from small creeks, streams, rivers, and lakes into the ocean. Some water starts the journey at the top of mountains as glaciers and travels into valleys and then to the ocean. Some water falls in the valley and has a shorter journey to the ocean.
If you look at a map of a watershed, it will look like the branches of a tree. Tiny branches join with larger branches, which join with even larger branches until they all join with the trunk of the tree.
Some watersheds are big (like the Fraser River watershed) while others are small. There can even be small watersheds inside bigger watersheds. But all watershed are made of:
Properties of a River
Parts of the River
If you are standing on the edge of a river, you may notice that it is actually made up of lots of different "parts".
Rivers Young and Old
There is one thing that you can be sure of - rivers are always changing. They change throughout the seasons as more or less water flows in them, and they change throughout the years, much like people do throughout their lifetimes. In fact, rivers are very much like people that way! When rivers are "young" they move fast, rushing towards the ocean, carrying lots and lots of stuff with them.
As rivers get older, they slow down, they don't move so fast, and they carry less and less dirt along with them.
Really old rivers can become lakes - they really don't move very much at all! But we know that rivers can be very, very powerful. Because year after year they move soil, sand and silt from their headwaters to their deltas. They cut paths right into hard, hard rock and create amazing landscapes along the way. Let's look at the ways that rivers are ever-changing.
Scientists are very interested in how fast the water in the river is flowing. This helps to know what plants, insects and animals can use the river, and how much "dirt" the water can carry. Lots of things control the speed of the water:
Did you know that cold water could hold more oxygen than warm water? Cool, hey. That is why fish need colder water to live in. So, it is important to know how warm or cold the water is in the river, because that can tell you if there is enough oxygen for the fish to breath. Lots of things control the temperature of the water in the river:
Other Stuff in the Water
Is the river in your back yard near the ocean? If it is, then the water may be affected by the ocean itself. The water level may go up and down with the tide, and the water may be somewhat salty. If you are near a big river close to the ocean, you will probably notice that there is a lot of dirt in the water - it is carrying sand and silt from high in the mountains down into the rivers "delta" (this is just a word that means a flat piece of land where the river slows down and sometimes branches into several channels).
Is there a lot of woody debris, logs or log jams in the river? These things provide excellent habitat for insects, and shelter for fish. They provide protection from predators, and cool places to rest.
The River Channel
A young river rushes straight to the ocean. An old river meanders around and takes its time. Look at a river over a long time (a really long time) and you can see that it changes its path many, many times. The water in the river will pick up rocks and sand from one spot and put it down at another location. Fast water washes plants, nutrients, sand and gravel into the river and then when it slows down (as it rounds a corner, or as the slope of the river becomes less) it drops them. A flooding river can pick up stuff and move it many kilometers away from where it came from. Look at the diagram below to see how a river changes course over time.
Who is Using the River?
Rivers are important for so many things . . . here are a few.
Habitat for Plants, Animals, Fish and Birds
Many different creatures and plants use rivers. Some live in them all the time, while others only spend a short part of their lives there. Though we don't often see many of them - and some are so tiny we often miss them - a collection of living creatures can be easily found in any stream. Scientists can tell how healthy a river is by the number of different creatures and plants found there. Some creatures are very sensitive to pollution, so if a scientist finds them, he can tell that the river is not polluted.
Food for thought . . . mayflies are sensitive to pollution. If you don't find a mayfly in your stream study, does this mean that the river is polluted?
Creatures so small you can only see them under a microscope, and creatures as large as grizzly bears rely on rivers for food, water, and shelter. Have a look at the picture to see how many animals use the rivers in your back yard.
We humans get a lot of enjoyment from rivers too. We use them for rafting, swimming, canoeing and boating, fishing, and viewing. Tourism is a very important part of our economy, but just knowing there are healthy rivers nearby is important to all of us.
Did you know that . . . 67% of B.C.'s tourist money comes from the Fraser River Watershed!
All through our history, rivers have been an important way to get around. Most explorers used rivers, streams and lakes to get across Canada. Rivers are still important for travel. Small boats to large ships use our rivers to transport goods and people.
Centres of settlements
Most of our cities and towns are located next to a major river. This is because the rivers were important for transportation when most of the towns were built. But it is also because rivers provide us with water, food, and recreation. They provide water for industry to use in manufacturing, and they provide a way to wash away our waste.
Rivers and streams are places where gold can collect. Placer mining (or gold panning) is a method of taking the gold out of stream beds. Other mines use the water from the rivers to help them drill, to process the raw ore, and to transport the ore to market.
Loggers use the rivers to help them transport and sort logs. Because the wood floats, it is one way of moving the heavy logs around, and loading them onto boats or trucks.
Other industry, such as pulp mills, use the water from the rivers to mix chemicals, cool off processes, or dilute waste.
Sometimes industries and sewage treatment plants dump pollution into the river so that it will be diluted and carried to the ocean.
Dams and Electricity
Rivers are very powerful, and they have a lot of energy. So they are often dammed to give us electricity to run our homes, industries and businesses. Sometimes they are dammed to help control flooding, or to divert water to farms. But every kind of dam can have huge impacts on the river.
The immense runs of Pacific salmon to the Fraser provided a predictable supply of food for First Nations people and colonists alike and have sustained a valuable commercial fishery to the present day. There are six species of salmon living in the Fraser River Watershed, and the system is known to be the greatest salmon river in the world. About 65 species of fish make the Fraser River Basin their home.
Water from rivers is often diverted so that it can be used to water farms and farm animals. In fact some rivers in the world go dry long before they reach the ocean because farmers have used all of the water to grow crops. This is called irrigation, and it is one of the strongest pressures on our rivers. Chemicals used in farming such as herbicides or pesticides can also find their way into rivers, and may kill plants and animals. Over time rivers can become "dead" - the water looks clean and clear, but nothing is living in it.