what are water various??
Answers
Answer:
Water can occur in three states: solid (ice), liquid or gas (vapor). Solid water – ice is frozen water. ... This is the form of water with which we are most familiar. We use liquid water in many ways, including washing and drinking. Water as a gas – vapor is always present in the air around us.
Explanation:
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Answer:
Water is a valuable natural resource that is found in different forms in the environment. It is important to understand how water moves through the environment so that we can understand how to manage it successfully. Fresh water is finite and vulnerable. Supplying sufficient clean, fresh water is one of the most vital natural resource issues facing humanity. Water shortages are becoming a global issue, due to an increasing population, economic growth and climate change. A lack of clean, fresh water can hinder the efforts to reduce poverty and progress national development, resulting in poor health, low productivity, food insecurity and restricted economic development.
Explanation:
1. The hydrological or water cycle
The hydrological cycle, or water cycle, is the continuous circulation of water between oceans, atmosphere and land (Figure 4.1). The sun and wind cause water to evaporate (change its physical state from liquid to gas) from land and water bodies (oceans, lakes and rivers). Also, plants take up liquid water and give off water vapour through pores in their leaves in a process called transpiration. The water vapour moves high above the Earth’s surface on rising currents of air through the atmosphere. Eventually as the water vapour reaches the cooler air higher up in the atmosphere, it condenses (changing from gas to liquid) to form clouds and falls back to Earth in the form of rain and snow (together these are called precipitation). Precipitation that falls on land can flow over the surface as run-off into rivers and streams, and can also percolate (trickle down) through the soil into underground rocks to become groundwater.
2 Distribution of water resources
About two-thirds of the Earth’s surface is covered with water. The total amount of water on the Earth is about 1400 million km3 (UNEP, 2002). Of this, around 97.5% by volume is held in the oceans and is salt water. Only 2.5% (or about 35 million km3) is fresh water.
Fresh water is water with a dissolved salt concentration of less than 1%. Globally, fresh water is distributed unevenly. About three-quarters of global annual rainfall occurs in countries containing less than one-third of the world’s population. About 80% of the world’s water run-off is concentrated in countries in northern and equatorial regions, which have relatively small populations. For example, the Amazon River in South America accounts for 20% of global run-off each year. The area drained by the Amazon is huge, but it is sparsely populated. In Africa, the Congo River and its tributaries account for 30% of the entire continent’s annual run-off, but the Congo’s area contains only 10% of Africa’s population.
3 Sources of water
Our main sources of water for drinking, washing, agriculture and industry are surface water, groundwater and collected rainwater, all of which are dependent on rain and snow falling on the Earth’s surface.
- Surface water
Rivers, streams, lakes, and ponds are widely used as water sources in Ethiopia, especially in rural areas (Figure 4.5). The amount of available surface water depends largely on rainfall. When rainfall is limited, the supply of surface water will vary considerably between wet and dry seasons and also between years. One way to overcome this problem is to construct a dam across a river to create a reservoir that provides water storage.
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- Rainwater
Rainwater is also an important source of water, although on a relatively small scale. Collecting rain from roofs or other hard-surfaced areas and storing it until it is needed can provide a valuable source of water for many purposes.
4. Water source selection
The quantity, quality, and reliability of available water are three main factors that need to be considered when evaluating water sources. Socio-cultural and technical issues may also be important. This section provides an overview of some of these different factors.
- Water quantity
If you were selecting a new source of water for a community you would need to be sure that the volume of water that could be supplied would be sufficient to meet the community’s needs, both now and in the future. It would also be important to consider the reliability of the source over time.
- Water quality
The quality of water required depends on what it will be used for. Drinking water must be clean and safe to drink and protected from any contamination by pathogens or other pollutants. The primary concern must be to prevent the transmission of waterborne diseases. For other water uses such as for domestic washing or for agricultural or industrial uses, the quality is less critical.