

Introduction
For the luck of we human beings, earth is a watery place. On earth, water exists in different forms like oceans, rivers, water vapours in the air, icecaps, glaciers, aquifers, and soil moisture. These are all the water resources of Earth. Approximately 71% of the earth’s surface is covered with water, and 97% of all Earth's water is held by the ocean. Only 3% is held in by rivers, lakes, underground water, etc.
Due to the water cycle, Earth’s water supply is constantly moving from one place to another place and from one form to another form. In this article, we are discussing the availability of water on Earth and the availability of water resources
Water Availability
The meaning of availability is the quantity of something that can be used. Water availability is the quantity of water that can be useful to human beings without causing any harm to the ecosystem or other living creatures. According to the statistics, almost 97% of the earth's water is saline, and among the available 3%, aquifers are considered economically useful water resources for human beings.
Water availability, both surface water and groundwater, is crucial for various fields like agriculture, industry, energy generation and most importantly, human consumption. Climate, local geological conditions, use of land, quality of water everything will affect the water availability.
Availability of Water on Earth
Approximately 71% of the earth’s surface is covered by water. Water on earth can be divided into underground water and surface water. Surface water includes water from the ocean, lakes, rivers, icetops, and glaciers. Among these freshwater resources are water falling from the sky, lake, rivers, streams and underground water.
Underground water is the water below our feet that is more important to live. Surface water is mainly used for agricultural needs and as drinking water, whereas groundwater helps to keep rivers and lakes full. More than 8,400,000Km3 of freshwater is available on earth. Most of it is stored in ice caps and glaciers in the polar regions.
The water cycle has a crucial role in the availability of water on earth. Due to the water cycle, water on the earth moves from one place to another, and because of it, water reaches animals and plants. The water cycle is driven by solar energy. Deforestation, climate changes, the channeling and diverting of waterways, etc. can influence the water cycle and thereby the availability of water on earth.
Water Resources
The meaning of water resources is the natural resources of water that can be useful to human beings. We are using water resources mainly as a source of drinking water and for agricultural purposes, household activities, environmental activities, and industrial purposes. Among the available water resources oceans are contributing 97% to the water availability. Underground water, surface water like rivers and lakes, and frozen water are the natural sources of freshwater.
Desalinated water and water obtained after wastewater treatments can be considered artificial water resources. Water pollution, climate change, scarcity of water and various human activities badly affect water resources.
Availability of Water Resources
Natural water resources can be broadly classified as surface water, underground water and frozen water. Surface water resources are oceans, lakes and rivers. Aquifers are economically useful groundwater. Water from ice caps and glaciers belongs to the category of frozen water resources.
Saltwater: About 97% of the earth's water is held by oceans. The sea water is salty because of the presence of chloride and sodium ions on a large scale. Along with that, elements like calcium magnesium, potassium, etc., are also found in seawater. Saltwater cannot be drunk directly or cannot be used for irrigation. To use salt water for human needs, it should undergo a desalination process. For people living in dry places, the desalination process provides much more fresh water.
Ice- 2.06%: Most of the freshwater on earth is stored in the form of ice. In the north and south poles, ice is found as ice caps, and in the mountains, it is found in the form of glaciers. Approximately 90% of the earth’s ice can be seen in Antarctica.
Groundwater- 0.9%: Groundwater has been seen in every place on the earth below our feet. During rain, rainwater is filtered through the soil and reaches the area where it is already saturated with water. Depending on the depth of these areas groundwater can be days to thousands of years old. Aquifers are the places where groundwater collects in water wells and are the most economical water resources for human beings.
Lakes- 0.008%: Lakes are formed either by the accumulation of snow or by the seeping out of groundwater to the surface of the earth. Lakes can contain both freshwater and salty water. Freshwater lakes are highly important for people.
Wetlands- 0.0001%: Wetlands are formed in areas where water covers the soil for a long period of time. Deltas, estuaries, marshes and swamps are wetlands. wetlands are places where both land-dwelling and aquatic animals can coexist.
Interesting Facts
The depth of Earth’s oldest lake Lake Baikal in Siberia, is 1,500 m
If all the ice on earth melted at once, the sea level would increase by 20 feet.
The Great Artesian Basin In Australia is the largest aquifer in the world.
Key Features
Water availability is the amount of water available for human purposes without harming the ecosystem.
The natural resources of water are called water resources.
Water resources can be classified into surface water, groundwater and frozen water.
Only 3% of water is freshwater, and 97% of the water on earth is salty.
FAQs on Water Availability: A Detailed Summary
1. What is the definition of water availability?
Water availability refers to the quantity of water that can be accessed and used by humans for needs like drinking, agriculture, and industry, without causing harm to the ecosystem. It considers not just the amount of water but also its quality and accessibility.
2. What percentage of Earth's water is freshwater, and where is it found?
Only about 3% of all water on Earth is freshwater. The vast majority, around 97%, is saline water in oceans. Of the available freshwater, most is not easily accessible as it is locked in:
- Ice caps and glaciers: This is the largest reservoir, holding over two-thirds of the world's freshwater.
- Groundwater: This water is stored underground in soil and rock layers called aquifers, making up most of the remaining freshwater.
- Surface water: A very small fraction is found in lakes, rivers, and wetlands.
3. What is the difference between groundwater and surface water?
Surface water is the water you can see on the Earth's surface, such as in rivers, lakes, and streams. It is mainly replenished by rainfall. Groundwater, on the other hand, is water that has soaked into the ground and is stored in underground layers of rock and soil. It is a crucial resource that feeds springs and keeps rivers flowing, especially during dry periods.
4. What are the main factors that affect water availability in a region?
Several factors influence a region's water availability. The key ones include:
- Climate: The amount of rainfall and the rate of evaporation are primary determinants.
- Geology: The type of rock and soil affects how much water can be stored underground.
- Pollution: Contamination from industrial or agricultural sources can make water sources unusable.
- Human Activities: Over-extraction for farming, deforestation that reduces rainwater absorption, and the construction of dams can significantly alter water availability.
5. How do human activities like deforestation impact the availability of groundwater?
Deforestation significantly reduces groundwater availability. Tree roots create natural channels in the soil that help rainwater to percolate deep into the ground, which recharges underground aquifers. When forests are cleared, the soil often becomes compacted. As a result, rainwater tends to run off the surface quickly instead of soaking in, leading to lower groundwater levels and an increased risk of both floods during heavy rain and droughts during dry spells.
6. Why are ice caps and glaciers considered a freshwater resource if we can't access them directly?
While we cannot directly tap into ice caps and glaciers, they are the world's largest natural reservoir of freshwater. They are crucial because their seasonal melting is the primary source that feeds many major rivers, which millions of people depend on for their water supply. Their existence is also vital for regulating global climate and maintaining sea levels.
7. Is saltwater from oceans completely useless for human needs?
No, saltwater is not useless. Although it cannot be consumed or used for irrigation directly due to its high salt content, it can be converted into freshwater through a process called desalination. This technology removes salt and other minerals, making it safe for human use. For many dry, coastal regions, desalination is a vital and growing source of freshwater.
8. How does the water cycle ensure the continuous availability of water on Earth?
The water cycle acts as Earth's natural purification and distribution system, ensuring water is continuously available. Solar energy causes water from oceans and lakes to evaporate into the atmosphere. This water vapour cools and condenses to form clouds, eventually falling back to Earth as precipitation (rain or snow). This process replenishes rivers, lakes, and groundwater, effectively recycling and redistributing the planet's finite water supply.





