|Special Public Works Programmes - SPWP - Community Water Supply - A Community Participation Training Element for SPWP User Beneficiaries (ILO - UNDP, 1987, 100 p.)|
|SESSION 5: How Does the Water Get There?|
Read the definitions of the USEFUL WORDS. Discuss their meanings with your group and your discussion leader. Can you translate them into your own language?
Read about the Water Cycle, Surface Water and Ground Water. Your discussion leader will answer any questions you have.
Use the DISCUSSION OPPORTUNITY to talk with other participants about water sources in your community.
VAPOUR - the gaseous state of water. Steam from boiling water is VAPOUR.
EVAPORATE - to change from water into vapour.
AQUIFER - an underground layer of sand or gravel which holds water. Also known as the water table.
Read the questions that follow. Do you know the answers?
1. How does water get under the ground?
2. Why do we sometimes have to dig through dry soil in order to find good drinking water?
3. A child plays in a stream and he gets his skin and clothes wet. But one hour later, he is dry. What happened to the water?
4. Where is the water that made the boys clothes and skin wet?
5. How does water get into the clouds?
6. Where does rain come from?
Continue reading and you will find the answers.
THE WATER CYCLE
The answers to all of the above questions can be found in the water cycle. It works like this.
The Water Cycle
Water or snow goes around in a cycle (circle). It falls, as rain, hail, or snow. Some of this rain, hail or snow will run off the land into rivers, streams, dams, lakes and ponds. Some will eventually reach the sea. Some of the water will soak into the ground (especially if the ground is covered with trees and bushes with roots to hold the water and soil). This water stays in the ground and may collect in an aquifer. (REMEMBER: An Aquifer is an underground area where water collects).
Now, you can understand the answers to questions 1 and 2. ONE, water gets into the earth from the rain that falls on the earth and then soaks through the ground to the aquifer.
The answer to question TWO is, wells are dug through the dry soil and into the aquifer where cool, clean water can be pumped up for your use.
The Well is Dug Down to the Aquifer
Think about question THREE. What happened to the water on the boys skin and clothes? To answer this question you must understand the next part of the water cycle. EVAPORATION. Water can change from a liquid to a vapour (a gas). It evaporates. This means that it changes into a vapour and goes into the air. You cannot see it. It disappears from your sight, but it has not really disappeared. It has only changed form. It has EVAPORATED.
When the sun or the wind dries the water from skin or clothes, or from ponds or streams or puddles, the water changes from a liquid into a vapour.
Now you know what happened to the water on the boys skin and in his wet clothes. The water evaporated.
The answer to question FOUR, Where is the water that made them wet? is easy. The water is in the air.
Can you guess the answers to questions FIVE and SIX - How does water get into the clouds? and Where does the rain come from? Water vapour rises up in the air. It collects and forms clouds. In the clouds, the vapour changes back into liquid and falls as rain.
How does water get into the clouds? It gets there from the water vapour in the air.
Where does the rain that falls from the sky come from? It comes from the water on earth that is evaporated into the air.
Look again at the illustration of the water cycle. Do you see how water goes round in a cycle?
Now that you understand the water cycle, you can better understand the two types of water sources: surface water and underground water.
SURFACE WATER is water collected on the surface of the earth in streams, rivers, ponds, lakes, dams, seas and oceans. Surface water is often used for drinking water in rural areas because it is easy for people and animals to obtain. It is also easy, however, for people and animals to contaminate surface water.
Unless great care is taken to protect surface water from contamination, it may be a source of disease. For example, disease-causing micro-organisms may enter surface water if people or animals defecate or urinate in or near the water. It can also be polluted by trash or garbage put in the water. Another disadvantage of some surface water (e.g. ponds and dams) is that it can become a breeding area for flies and mosquitos which may carry disease.
If care is taken, however, it may be possible to use surface water for a good water system.
Ground water is water that has soaked and filtered through the top layers of earth and is held in a natural aquifer or an underground stream. This water is usually very pure and is a good source of drinking water.
Sometimes ground water is available from a spring. At the point where the spring comes out from the earth, it will be clean. It should be protected at that place so that it will not become contaminated before people can use it.
To use water from an underground aquifer, a well must be dug deep enough to reach the ground water. This will be pure and clean if people are careful not to contaminate it. (REMEMBER: The water could be contaminated by disease-causing micro-organisms from latrines that are too close to the well. The water could also become contaminated if dirty buckets or trash are put into the water.)
Ground water is almost always safe and cleaner that surface water. It may, however, be more difficult or expensive to obtain.