Surface Water Resources of India CP

 Surface Water Resources of India  CP

Although India possesses only 4% of the world's renewable water resources, it is home to roughly 18% of the world's population. India has an average annual precipitation of 4,000 billion cubic meters (BCM), making it the country's primary source of freshwater. Surface water, subsurface river flow, groundwater, and frozen water are all-natural sources of freshwater. Treated wastewater (reclaimed water) and desalinated seawater are two examples of artificial freshwater sources

Before discussing about surface water resources of India, lets first discuss about the distribution of Water on the Earth

Distribution of Water on Earth

• Water resources are natural water resources that have the potential to be used as a source of water.
• Saltwater makes up about 97 per cent of the world's water.
• Freshwater makes up only 3% of the total, with slightly more than two-thirds frozen in glaciers and polar ice caps. The remaining unfrozen freshwater is mostly found as groundwater, with only a little amount found above ground or in the atmosphere.

Availability and Potential of Water Resources in India

• India covers around 2.45% of the world's surface area and has 4% of the world's water resources.
• In India, rainfall is the primary source of freshwater. For a country of its size, India receives the second most amount of rainfall.
• India receives an average of 1,170 millimeters (46 in) of rain per year, which equates to around 4,000 cubic kilometers (960 cu miles) of rain per year, or about 1,720 cubic meters (61,000 cu feet) of freshwater per person.
• Water Resources of India can be classified into:
1. Surface water Resources
2. Groundwater Resources

Surface Water Resources

• In India, there are four significant surface water resources. They are rivers, lakes, ponds, and tanks.
• In India, there are around 10,360 rivers and their tributaries with a length of more than 1.6 kilometers.
• The total yearly flow in India's river basins is estimated to be 1,869 cubic kilometers. However, only roughly 690 cubics (37%) kilometers of accessible surface water can be used.

This is because:

• A four-month period accounts for roughly 90 percent of the annual flow of Himalayan rivers.
• Capturing such resources is difficult and constrained because of the unavailability of adequate storage reservoir sites.
• The amount of water that flows through rivers is determined by the catchment basin, the size of the river basin, and the amount of rainfall that falls within the catchment basin.
• Within the catchment areas of the Ganga, Brahmaputra, and hence the Barak rivers, precipitation is abundant. These three rivers cover less than a third of India's total land area. However, it controls 60% of India's surface water resources.
• The southern rivers, on the other hand, have significant flow variability throughout the year.

Groundwater Resources

• The country's total replenishable groundwater resources are around 432 cubic kilometers.
• About 46% of the total replenishable groundwater resources are found in the Ganga and Brahmaputra basins.
• In the river basins of the northwestern area and sections of south India, groundwater utilization is relatively high.
• India also relies heavily on groundwater resources, which account for more than half of all irrigated land and serve 20 million tube wells.
• To conserve river waters and improve groundwater recharging, India has built about 5,000 major or medium dams, barrages, and other structures.

Lagoons and Lakes

Lagoons and Lakes

• India contains a wide coastline and because of this, a diversity of lagoons and lakes have developed.
• States like Kerala, Odisha, and West Bengal have huge surface water resources in these lagoons and lakes.
• The water in these locations is habitually brackish.
• This brackish water is utilized to irrigate specific types of paddy, coconuts, and other crops, the water bodies are also used for fishing.

Dams And Rivers

Dams And Rivers

• To store river waters and improve ground water recharging, India has built nearly 5,000 major or medium dams, barrages, and other structures.
• The major dams (59 in total) have a total storage capacity of 170 billion cubic meters.
• About 15% of India's food is produced with groundwater resources that are rapidly depleting or being mined.
• The end of an era of massive groundwater use expansion will necessitate a greater reliance on surface water supply systems.

Usage of Water

Usage of Water

• Irrigation is by far the biggest consumer of India's water reserves, accounting for 78 percent of total water reserves, followed by the household sector(6%), and the industrial sector (5%).
• In both urban and rural India, groundwater is a key supply of drinking water. Groundwater reserves provide 45 percent of total irrigation and 80 percent of household water.
• In some states, overuse of groundwater has led to a major scarcity of water.

• Water availability of fewer than 1700 m3 per capita per year is defined as 'water strained,' while less than 1000 m3 per capita per year is classified as 'water scarcity,' according to international standards.
• In India, surface water availability was 2309 m3 in 1991 and 1902 m3 in 2001, respectively.
• However, by the years 2025 and 2050, per capita surface water availability is expected to be reduced to 1401 m3 and 1191 m3, respectively.
• In 2010, per capita, water availability in the country was 1588 m3, compared to 5200 m3 in 1951.