Brief Notes On Water Resources

Water resources refers to natural resources of water that are potentially useful as a source of water supply. About 97% of the water on the Earth is mainly salt water and only around 3% is fresh water; approximately around two thirds of this is frozen in glaciers and polar ice caps. The remaining unfrozen freshwater can be found mainly as groundwater, only a small fraction is present above the ground or in the air. Natural sources of fresh water comprises surface water, under river flow, groundwater and frozen water. Artificial sources of fresh water might include treated wastewater (reclaimed water) and also desalinated seawater.

Use of Water Resources

Water resources can be used for agricultural, industrial, domestic, recreational, and environmental activities. Majority of the users need fresh water.

However, around 97% of water found on the earth is salt water and only around 3% is fresh water. Around two-thirds of the available fresh water is frozen in glaciers and polar ice caps. The remaining freshwater can be found usually as groundwater and a negligible portion of it is present on the ground or in the air.

Following are a brief account of how water is used in different sectors.

Agricultural Use

Agriculture consumes over 69 percent of all water in agricultural economies such as India. As a result, agriculture is the world’s largest consumer of accessible freshwater.

Agriculture’s global water demand is expected to rise by 19 percent by 2050 due to irrigation needs. Increased irrigation demand is projected to place undue strain on water reserves. It’s also unclear whether further irrigation development, as well as increased water withdrawals from rivers and groundwater, will be doable.

Use in Industry

The industry’s lifeblood is water. It’s utilised as a cooling for raw materials, a solvent, a transport agent, and an energy source. Manufacturing accounts for a significant portion of total industrial water usage. Water is used extensively in industries such as agriculture, allied products, chemicals, and primary metals. The industry represents around 19% of overall consumption worldwide. Industry, on the other hand, consumes more than half of the water available for human use in developed countries.

Domestic Use

It encompasses drinking, cleaning, personal hygiene, gardening, cooking, clothing, dishwashing, and vehicle maintenance, among other things. People have been moving out of the countryside and into ever-expanding cities since the end of World War II. This tendency will have a significant impact on our water resources. To distribute water to expanding populations and industry, the government and towns have had to start developing major water-supply systems. Domestic water use accounts for around 12% of global water consumption.

Use for Hydropower Generation

Hydropower is electricity generated by water. Hydropower is the world’s most widely used renewable energy source. It generates around 16 percent of the world’s total electricity. There are several hydropower development prospects all throughout the world. China, the United States, Brazil, Canada, India, and Russia are the world’s top hydropower producers now.

Use for Navigation and Recreation

Watercourses that have been or may be used for interstate or international commerce are known as navigable waterways. In many parts of the world, agricultural and commercial items are transported by water on a vast scale. Recreational activities such as boating, swimming, and sporting activities are all done on the water. These activities disrupt the water’s quality and thus, pollute it. While allowing such operations in reservoirs, lakes, and rivers, the highest priority should be given to public health and drinking water quality.

Natural sources of freshwater

Natural sources of fresh water comprises surface water, under river flow, groundwater and frozen water.

Surface Water

Water in a river, lake, or freshwater wetland is known as surface water. Precipitation refills surface water, while discharge to the oceans, evapotranspiration, evaporation, and groundwater recharge deplete it. Although precipitation within a watershed is the only natural input to any surface water system, the overall amount of water in that system at any given time is influenced by a variety of other factors. Storage capacity in lakes, marshes, and artificial reservoirs, permeability of the soil underlying these storage bodies, runoff characteristics of the land in the watershed, precipitation timing, and local evaporation rates are among these aspects. All of these elements have an impact on water loss proportions.

Under river flow 

The total volume of water delivered downstream by a river is typically a combination of visible free water flow and a significant contribution flowing via rocks and sediments that lay beneath the river and its floodplain, known as the hyporheic zone. This invisible component of flow may substantially exceed the visible flow for many rivers in big valleys. The hyporheic zone is a dynamic interface that exchanges flow between rivers and aquifers that are either fully charged or depleted. This is especially true in karst environments, which are prone to potholes and subsurface rivers.

Groundwater

Groundwater is a type of freshwater that is found in the pore space of soil and rocks under the surface. It also includes water that flows beneath the water table in aquifers. It’s occasionally helpful to distinguish between surface water-associated groundwater and deep groundwater in an aquifer (sometimes referred to as “fossil water”).

Inputs, outputs, and storage are generally the same for groundwater as they are for surface water. The crucial difference is that, due to its slow turnover rate, groundwater storage is often substantially bigger (in volume) than surface water storage when compared to inputs. Because of this disparity, humans can utilise groundwater in an unsustainable manner for an extended period of time without suffering serious effects. Nonetheless, the average rate of seepage above a groundwater source represents the upper bound for typical water intake from that source over the long run. Seepage from surface water is a natural source of groundwater input. Natural groundwater outflows include springs and seepage into the oceans.

Frozen Water

Several strategies to use icebergs as a water source have been proposed, however this has only been done for research purposes so far. Surface water is referred to as glacier runoff. The Himalayas, dubbed “The Roof of the World,” are home to some of the world’s most vast and rugged high altitude terrain, as well as the world’s largest glaciers and permafrost outside of the poles. Ten of Asia’s greatest rivers originate there, and more than a billion people rely on them for survival. To make matters worse, temperatures in the area are rising faster than the world average. Over the last decade, the temperature in Nepal has risen by 0.6 degrees Celsius, while the Earth has warmed by about 0.7 °C  globally.

Artificial Sources of Water

Treated wastewater (reclaimed water) and desalinated seawater are two examples of artificial fresh water sources. However, the economic and environmental consequences of these technologies must be considered.

Conclusion

Our water resources, which are dispersed over space and time, are under strain as a result of rapid population growth and growing demand. Access to trustworthy data on the availability, quality, and quantity of water, as well as its variability, is essential for effective water resource management.