WHY THE WATER CYCLE IS IMPORTANT

All life on earth is reliant on the water cycle. Our bodies need lots of water to perform various biological processes. In fact, up to 60% of the human body is made up of water. 

We can go for several days without food but can only survive for a few days when it comes to water. Crucial organs of the body like the heart and the brain contain up to 73% water. 

As you can see, without water, life will cease to exist on our planet. It’s not only humans that will die but also plants and animals.

Thanks to the water cycle, all life forms on earth can get water whenever they need it.

The water cycle, also known as the hydrolic cycle, is a natural process that describes the movement of water on, below, and above the surface of the earth.

• Water can change state during the water cycle. E.g. liquid to gas, solid to liquid, etc. 
• The water cycle is made of a series of interconnected pathways that allow the above processes to occur efficiently. These pathways involve both abiotic and biotic components of the environment.
• When water evaporates, it can condense into the atmosphere to form clouds. The clouds then release the water as precipitation in the form of snow or rain.
• The water that falls back to the ground can collect in an area, thereby forming lakes, ponds, and rivers. However, some of is absorbed into the soil where plants can easily access it.
• Plants don’t use up all the water that is absorbed as some of it is released back into the atmosphere. This allows the cycle to repeat itself over and over again.
• Through this process, all living organisms will get water, thus creating balance within the ecosystem.
• The water cycle is a never-ending process, and it also doesn’t have a specific starting point.
• Nonetheless, that does not mean that the process cannot be explained. We can better understand the water cycle by studying how water moves from large water bodies to the atmosphere.
• Oceans, lakes, and rivers contain large volumes of water which changes state from time to time depending on the weather conditions.

The hydrolic cycle consists of five important processes. These processes allow water to change from one state to another.

1. Evaporation

• This is the process through which water changes to vapor.
• In the water cycle, evaporation occurs when solar energy breaks the bonds that hold the water molecules. This causes the molecules to vibrate and move into the atmosphere.
• Most of the water in the clouds is a result of the evaporation process.
• Aside from large water bodies, water can evaporate from the soil or any other surface that contains water.

2. Transpiration

• Transpiration is the process by which plants release water vapor into the environment through the stomata.
• Transpiration occurs during photosynthesis as plants make their food.
• Research shows that up to 10% of the water in our atmosphere comes from transpiration.
• Plants contribute a lot to the water cycle.

3. Sublimation

• Sublimation is the process through which ice changes to water vapor directly without melting first.
• This process occurs when ice absorbs heat energy from the environment.

4. Condensation

• Condensation is the process through which water vapor changes to liquid form. It is the exact opposite of evaporation.
• In the hydrolic cycle, the water vapor that rises into the atmosphere condenses to a liquid state.
• For condensation to occur, warm vapor must be exposed to cold conditions. And since the temperatures in the atmosphere are low, the water vapor can easily change to liquid.
• As water vapor condenses, clouds are formed in the atmosphere.

5. Precipitation

• Precipitation occurs when clouds can longer hold the large volumes of water that form after condensation. It mainly occurs in the form of snow and rain. 
• Through precipitation, water can move from the atmosphere to the ground. The process also allows water to return to the oceans, lakes, rivers, and streams.
• Water that has fallen onto the ground can travel through different layers of soil through a process called percolation.

Read more at Water Science School

These processes can repeat themselves multiple times provided that the conditions are right. They can help us explain the water cycle steps without leaving the important facts out.

Humans affect the water cycle in various ways. This mainly occurs through the activities that people engage in. These effects can bring about both global and localized environmental consequences.

People clear away natural vegetation to create space for crops. And this affects the movement of water from plants into the atmosphere due to reduced vegetation cover.

A lot of water is also lost through irrigation as it drains rivers and lakes. Poorly maintained irrigation systems can cause surface run-offs.

Agricultural practices cause a change in the drainage pattern since farmers have to dig trenches to meet their drainage needs.

Deforestation is the removal of a large number of trees over a wide area.

Trees contribute a lot to the water cycle when they transpire. As such, their destruction can have a serious impact on how water moves into the atmosphere.

When trees are few, less water will evaporate, meaning there will be little or no rainfall.

The production of electricity in dams requires large volumes of water. When rivers are dammed, it affects the natural flow of the water.

This reduces the amount of water that flows downstream. As a result, the plants that are on the other side of the river won’t get enough water to transpire.

Read more at Science Learning Hub: Humans and water cycle

Without the water cycle, the earth will run out of fresh water in a matter of days. Besides, only 3% of the earth’s water is considered fresh. Out of this percentage, only 1.2% of the water is readily available for drinking. The remaining percentage of water is still locked up in ice caps and glaciers. So we mustn’t interfere with the water cycle.

Read also: Why biodiversity is so important?

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