What Is Water Availability Definition Sources Factors and Importance
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 in Environmental Chemistry
1. What is water availability in chemistry?
Water availability in chemistry refers to the amount of usable freshwater (H2O) accessible for human, agricultural, and industrial use. Only about 2.5% of Earth’s water is freshwater, and less than 1% is readily available in rivers, lakes, and groundwater. In chemistry and environmental science, water availability is linked to water quality, dissolved ions, pH, salinity, and contamination levels that affect its suitability for drinking, reactions, and industrial processes.
2. Why is freshwater limited on Earth?
Freshwater is limited because most of Earth’s water exists as saline water in oceans and a large portion of freshwater is locked in glaciers and ice caps. Key reasons include:
- About 97.5% of water is saline (high NaCl concentration).
- Nearly 69% of freshwater is frozen in ice.
- Much of the remaining freshwater is deep groundwater, not easily accessible.
- Pollution reduces usable freshwater availability.
3. What is meant by potable water in chemistry?
Potable water is water that is chemically and biologically safe for drinking. It must:
- Have a near-neutral pH (around 6.5–8.5).
- Contain low concentrations of harmful ions such as Pb2+, Hg2+, or excess NO3-.
- Be free from pathogenic microorganisms.
4. What is the difference between hard water and soft water?
The main difference between hard and soft water is the presence of dissolved Ca2+ and Mg2+ ions in hard water.
- Hard water: Contains Ca2+ and Mg2+ (e.g., from CaCO3), forms soap scum.
- Soft water: Contains little or no Ca2+ and Mg2+, lathers easily with soap.
5. How does water pollution affect water availability?
Water pollution reduces water availability by making freshwater chemically unsafe or unusable. Pollutants include:
- Heavy metals like Pb2+ and Cd2+.
- Excess fertilizers containing NO3- and PO43-.
- Industrial acids or bases altering pH.
6. What is desalination and how does it increase water availability?
Desalination is the process of removing dissolved salts, mainly NaCl, from seawater to produce freshwater. Common methods include:
- Reverse osmosis (membrane separation under pressure).
- Distillation (evaporation and condensation of H2O).
7. How is water purified in a water treatment plant?
Water is purified through physical and chemical processes that remove suspended particles, dissolved ions, and microbes. Main steps include:
- Coagulation and sedimentation (using chemicals like Al2(SO4)3).
- Filtration through sand or activated carbon.
- Disinfection using chlorine: Cl2(g) + H2O(l) → HCl(aq) + HOCl(aq).
8. What is the role of the water cycle in water availability?
The water cycle maintains water availability by continuously recycling H2O through evaporation, condensation, and precipitation. Key stages include:
- Evaporation: Liquid H2O → water vapor (physical change).
- Condensation: Vapor cools to form clouds.
- Precipitation: Rain replenishes surface and groundwater.
9. What is groundwater and why is it important for water availability?
Groundwater is freshwater stored beneath Earth’s surface in aquifers within porous rocks and soil. It is important because:
- It supplies a large fraction of drinking water globally.
- It is naturally filtered through soil layers.
- It is less affected by short-term climate variations.
10. How can chemistry help improve water availability?
Chemistry improves water availability through water treatment, desalination, recycling, and pollution control. Applications include:
- Designing better membranes for reverse osmosis.
- Developing efficient coagulants and disinfectants.
- Monitoring water quality using chemical analysis (pH, ion concentration, titration).
