For drinking and irrigation purposes, the availability of suitable water out of earth’s total water supplies is about less than
1%
Understanding Earth's Water Availability
Earth is often called the "blue planet" because of the vast amount of water covering its surface. However, not all of this water is easily accessible or suitable for human uses like drinking and irrigation. Let's look at how Earth's total water supply is distributed.
Distribution of Total Water on Earth
The total volume of water on Earth is immense, estimated to be around $1.386 \times 10^9$ cubic kilometers. This total water is divided into two main categories:
- Saltwater: Found mostly in oceans and seas.
- Freshwater: Found in glaciers, ice caps, groundwater, lakes, rivers, soil moisture, and the atmosphere.
The vast majority of Earth's water is saltwater.
| Water Type | Percentage of Total Water |
|---|---|
| Saltwater (Oceans, Seas, Saline Groundwater) | Approximately 97.5% |
| Freshwater | Approximately 2.5% |
Where is Freshwater Located?
Even though 2.5% of Earth's water is freshwater, most of it is not easily available for our use. Freshwater is stored in various forms:
- Ice and Glaciers: The largest portion of freshwater is locked up in ice sheets and glaciers, mainly in Antarctica and Greenland. This accounts for about 68.7% of total freshwater.
- Groundwater: This is water stored beneath the Earth's surface in aquifers. It makes up about 30.1% of total freshwater. Some of this groundwater is deep or saline and not easily accessible or suitable.
- Surface Water and Other Freshwater: This includes lakes, rivers, swamps, soil moisture, and atmospheric water. This is a very small percentage of total freshwater, only about 1.2%.
| Freshwater Location | Percentage of Total Freshwater | Percentage of Total Water |
|---|---|---|
| Ice and Glaciers | ~68.7% | ~1.7% ($0.687 \times 0.025$) |
| Groundwater | ~30.1% | ~0.76% ($0.301 \times 0.025$) |
| Surface Water and Other | ~1.2% | ~0.03% ($0.012 \times 0.025$) |
Suitable Water for Drinking and Irrigation
Water suitable and readily available for drinking and irrigation primarily comes from surface water sources like lakes and rivers, and accessible groundwater. The percentage of total water represented by these sources is quite small.
- Surface water (lakes, rivers, etc.) is about 0.03% of Earth's total water.
- Accessible groundwater contributes more, but not all groundwater is easily reachable or non-saline. Even considering a significant portion of groundwater combined with surface water, the total amount readily available for human consumption and irrigation is significantly less than 1% of the Earth's total water supply.
Various estimates place the percentage of readily accessible freshwater for human use (drinking and irrigation) in the range of about 0.007% to 0.3% of Earth's total water. Regardless of the exact figure within this range, it is clearly a very small fraction.
Conclusion on Water Availability
When considering Earth's total water supplies, the amount suitable and readily available for drinking and irrigation is the portion of freshwater that is easily accessible surface water or groundwater. Based on the distribution figures, this readily available amount is substantially less than 1% of the total water on the planet.
Revision Table: Key Water Facts
| Water Category | Approximate Percentage of Total Water |
|---|---|
| Saltwater | 97.5% |
| Total Freshwater | 2.5% |
| Freshwater in Ice/Glaciers | 1.7% |
| Freshwater in Groundwater | 0.76% |
| Freshwater in Surface Water/Other | 0.03% |
| Readily Available Freshwater for Drinking/Irrigation | < 1% (typically much less, e.g., 0.007% - 0.3%) |
Additional Information on Water Resources
The scarcity of readily available freshwater is a major global concern. While the total amount of freshwater exists, its distribution and form (frozen, deep underground, or polluted) limit its usability. Climate change impacts glacier melt and precipitation patterns, further affecting freshwater supplies. Sustainable water management practices, including conservation, efficient irrigation techniques, and wastewater treatment, are crucial to ensure adequate water availability for future generations. Understanding the limited nature of this resource highlights the importance of protecting water quality and managing usage responsibly for both drinking and irrigation needs.
Important Questions from Basics of Environment
The Wild Life (Protection) Amendment Act, 2022 seeks to implement the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Which of the following statements is correct about CITES?
1. CITES is an agreement between governments to ensure that international trade in the specimens of wild animals and plants does not threaten the survival of the species.
2. Under CITES, plant and animal specimens are classified into five categories based on the threat to their extinction.
3. The Convention requires countries to regulate the trade of all listed specimens through permits.
4. It also seeks to regulate the possession of live animal specimens.
Given below are two statements : One is labelled as Assertion (A) and the other is labelled as Reason (R):
Assertion (A): Green hydrogen production will be critical for world community to achieve carbon neutrality by the year 2050.
Reason (R): The energy content of hydrogen gas is much higher than that of coal.
In the light of the above statements. choose the correct answer from the options given below :
Permafrost is defining characteristic of which biome?
Identify the features associated with Kyoto Protocol.
(A) Heavier burden on developed countries to cut down greenhouse gas emissions.
(B) International emissions trading.
(C) Nationally determined contributions.
(D) Clean Development Mechanism.
Choose the correct answer from the options given below:
Given below are two statements:
Statement I: Some microorganisms, especially protozoan, are able to survive conventional disinfection process.
Statement II: Some carcinogens, such as chloroform, are created during chlorination process.
In the light of the above statements, choose the most appropriate answer from the options given below:
