Give two example
1. insoluble subslandas-
2 sources of water
3.solition
4.complax machine
5.force
Answers
Answer:
1. Insoluble substances-
Example: Metals and wood
2. Sources of water-
Example: Rivers and lake
3. Solution
Example: Salt Water and Sugar Water
4. Complex machine-
Example: Bicycle and wheel barrow
5. Force-
Example: Magnetic Force and Gravitational Force
Answer:
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Study Session 3 Water Sources and their Characteristics
Study Session 3 Water Sources and their Characteristics
Introduction
Water collection for domestic use can be traced back to 560 BC when rainwater harvesting was practised in the Axumite Kingdom. In those days, rainwater was collected and stored in ponds for agriculture and water supply purposes. Evidence for this is in documented literature and may be observed in visible remains of ponds (Seyoum, n.d.). The history of modern piped water supply in Ethiopia began in 1924 when a piped supply was established from the Kebena River to the patriarch’s compound and Menelik Hospital in Addis Ababa, using an 80-mm pipe. Until the inauguration of the Gefersa Dam in 1951 the town of Addis Ababa was supplied from wells and springs (AAWSA, 2011).
Learning Outcomes for Study Session 3
When you have studied this session, you should be able to:
3.1 Define and use correctly all of the key words printed in bold. (SAQ 3.1)
3.2 Identify the different sources of water for urban supply, describe their characteristics and explain how water is abstracted from them. (SAQ 3.2)
3.3 Identify means of protecting water sources. (SAQs 3.3 and 3.4)
3.4 Describe briefly the factors to be considered in water source development. (SAQ 3.5)
3.1 Types of water source
In Study Session 1 you were introduced to the three main sources of water: groundwater, surface water and rainwater. In arid regions where seawater is accessible (such as in the Middle East), desalination (the removal of salts from water) is used to generate drinking water. Another potential source of water is treated wastewater – you will learn more about this in Study Session 11. In practice, the term ‘water source’ can be used to mean both the origin of the water and also the place where people get their water (spring, piped supply to household tap, water point, well, etc.).
Water sources can be classified as protected or unprotected. Protected sources are covered by stonework, concrete or other materials that prevent the entry of physical, chemical and biological contaminants. Typical characteristics of a protected water source are given in Box 3.1.
Box 3.1 Characteristics of a protected water source
The water source is fully enclosed or capped and no surface water can run directly into it.
People do not step into the water while collecting it.
Latrines, solid waste pits, animal excreta and other sources of pollution are located as far away as possible from the water source and on ground lower in elevation than the water source.
There is no stagnant water within 5 metres of the water source.
The water collection buckets or hand pump at the source are kept clean.
Why do you think there should be no stagnant water within 5 metres of a water source?
Reveal answer
Unprotected sources are those with no barrier or other structure to protect the water from contamination. All surface water sources, such as lakes, rivers and streams or poorly constructed wells, are examples of unprotected sources. Water from unprotected sources cannot be considered safe to drink unless it has been treated.