18 Nov Water Resorce

Water Resources: A Critical Component of the UPSC CSE Geography Syllabus

Target Audience: UPSC CSE Aspirants (Geography Optional & GS Paper I)

The Dynamics of the Water Cycle (Hydrological Cycle)

The circulation of water is highly dynamic and global in extent, involving the atmosphere, the sea, the earth, and the entire living biota. This continuous movement is sustained primarily by energy from the sun, which drives evaporation.

Key Processes in the Water Cycle:

• Evaporation: The process where liquid water changes into vapour at ambient temperature. Evaporation from the ocean surface is by far the largest single source of atmospheric water vapour.
• Transpiration: The loss of water in vapour form specifically from plant leaves. For instance, one hectare of corn can lose approximately 35,000 litres of water each day through transpiration alone.
• Condensation: The change of water from the vapour phase to a liquid state, typically forming dew droplets.
• Deposition: The process where water changes directly from vapour into a solid (ice crystals) phase. Tiny droplets of water and ice crystals formed through condensation and deposition create clouds.
• Sublimation: The direct change of solid water (like ice flakes) to the vapour phase without passing through the liquid phase.
• Precipitation: This includes all forms in which atmospheric moisture descends to earth, encompassing rain, snow, hail, sleet, and dew.
• Run Off: Excess water that flows over the land surface along the natural slope, replenishing rivers and lakes which ultimately drain into the sea. Run off also acts as an agent of soil erosion and rock weathering.

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Forms of Water Based on Salinity

Water on land exists broadly in three forms defined by their salt content:

1. Fresh Water: A universal solvent where the total salt content remains under 1.5 per cent. Dissolved salts are significant for floating aquatic vegetation and phytoplankton.
2. Brackish Water: Has an intermediate salinity range, typically between 0.5% and 3.5%. This water is characteristic of estuaries, where fresh river water mixes with sea water.
3. Marine Water: Highly saline, with an average salinity of 35 parts of salt per 1000 parts of water by weight (3.5%). Biotic activity is greatly restricted in highly saline habitats, though some salt lakes may exceed this level.

Groundwater Systems and Over-Exploitation

Groundwater is accumulated as precipitation percolates down through rocks.

• Aquifer: The layer of rock through which water percolates down and accumulates as groundwater.
• Zone of Aeration (Unsaturated Zone): The upper layer where gaps in the soil are filled both with air and water.
• Zone of Saturation (Saturated Zone): The lower layer where the gaps are completely filled with water.
• Water Table: The boundary separating the saturated zone from the unsaturated zone. Groundwater provides a constant supply and is not likely to dry up under natural conditions.

Usage Statistics:

Globally, agriculture is the single biggest consumer of water, consuming almost 70% of available water every year. This figure is even higher in Asia, where intensive agriculture has driven the annual water withdrawal rate up to 86% of the total withdrawal. The resource-intensive agriculture ushered in by the Green Revolution relied heavily on water inputs.

Degradation, Scarcity, and Management Strategies

Today, water resources face depletion and contamination, exacerbated by intensive agriculture, urbanization, industrialization, and deforestation. The paradoxical situation of lack of safe drinking water persists even in areas with abundant water bodies or above-average rainfall.

Major Degradation Issues:

• Pollution: Discharge of sewage and industrial effluents causes pollution.
• Eutrophication: Effluents often lead to an increase in aquatic plants and algal blooms, which can ultimately cause water bodies to decay and disappear.
• Siltation: Soil erosion causes siltation of rivers and lakes, progressively reducing their water holding capacity and contributing to severe floods.

Conservation and Management Strategies (UPSC Perspective):

Management aims to provide an adequate supply of good quality water without endangering the source, ensuring water of the right quality is available, and preventing misuse or wastage.

Projected Scarcity: Within the next 25 years, one-third of the world’s population will experience severe water scarcity.

1. Groundwater Recharging

This is the most important aspect of water management.

• In mountains and hills, vegetated watersheds allow infiltration of rainwater into aquifers.
• In urban and rural areas, rainwater infiltration can be promoted by feeding storm water or domestic drains into pits, trenches, or depressions.
• Flood water can be injected into aquifers through deep pits or spread on fields via ditches.

2. Inter-Regional Diversion

Water management includes diverting supply from an area of surplus to a region of scarcity. This not only benefits water-scarce regions but also helps mitigate the danger of flood damage.

3. Treating Waste Water

• Domestic and municipal waste water, rich in organic nutrients, can be treated to remove germs and toxic elements for use in industrial and agricultural irrigation.
• **Bioremediation:** Growing algae or water hyacinth serves a double purpose: it cleans the water of pollutants like phosphates and nitrates, and the plants themselves can be utilized for the production of **biogas**.
• **Chlorination:** Treatment with chlorine kills harmful germs and makes water usable.

4. Desalination of Sea Water

Fresh water of good quality can be obtained by distilling sea water using solar energy. This method is currently employed in India at places like Bhavnagar in Gujarat and Churu in Rajasthan.

 

The following 10 multiple-choice questions have been generated based on the provided source material on “Water Resources,” utilizing formats typical of the UPSC Civil Services Examination Prelims paper.

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10 Questions for UPSC CSE Prelims (Water Resources)

Question 1 (Resource Classification)

Which of the following statements regarding the classification of resources is/are correct?

1. Water is considered a renewable resource because it gets recycled.

2. The formation of a layer of top soil is a very slow process, taking thousands of years, hence it is classified as a non-renewable resource.

3. Forests and wild life are examples of natural resources that are regenerated from time to time by natural multiplication.

Select the correct answer using the code given below: (a) 1 only (b) 2 and 3 only (c) 1 and 3 only (d) 1, 2 and 3

Source-based Answer Explanation: All statements are directly supported by the sources.

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Question 2 (Water Cycle Processes)

With reference to the Water Cycle (Hydrological Cycle), consider the following processes:

1. Condensation: The process by which water changes directly from a vapour into a solid (ice crystals) phase.

2. Deposition: The process by which water changes from vapour phase to a liquid state (in the form of dew droplets).

3. Sublimation: The process by which solid water changes directly to the vapour phase without passing through the liquid phase.

How many of the above pairs are correctly defined? (a) Only one (b) Only two (c) All three (d) None

Source-based Answer Explanation: Statement 1 defines Deposition, not Condensation. Statement 2 defines Condensation, not Deposition. Statement 3 defines Sublimation correctly. Therefore, only one (Statement 3) is correct.

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Question 3 (Forms of Water and Salinity)

With respect to the different forms of water found on land, consider the following statements:

1. Fresh Water is a universal solvent and its total salt content invariably remains under 1.5 per cent.

2. Brackish water is characterized by a content of dissolved salts ranging between 0.5 and 3.5%.

3. Marine water typically has an average salinity of 35 parts of salt per 1000 parts of water by weight (3.5%), though some salt lakes may exceed this level.

Select the incorrect statement(s) using the code given below: (a) 1 only (b) 2 and 3 only (c) 3 only (d) None of the statements are incorrect

Source-based Answer Explanation: All three statements are factually correct as per the source definitions. Fresh water < 1.5%. Brackish water 0.5% to 3.5%. Marine water average 3.5%.

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Question 4 (Groundwater System)

Regarding the accumulation and movement of groundwater, which of the following statements is/are correct?

1. The layer of rock through which water percolates down and accumulates as groundwater is known as the aquifer.

2. The zone of aeration is the area where gaps in the soil are filled both with air and water, lying above the zone of saturation.

3. The water table is defined as the boundary between the saturated zone and the unsaturated zone in rock.

Select the correct answer using the code given below: (a) 1 only (b) 2 and 3 only (c) 1 and 3 only (d) 1, 2 and 3

Source-based Answer Explanation: All three statements accurately describe the components of the groundwater system as detailed in the source.

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Question 5 (Water Usage and Scarcity)

Consider the following statements concerning water consumption and global scarcity:

1. Agriculture is the single biggest consumer of water, accounting for almost 70% of available water consumed worldwide every year.

2. Due to resource-intensive agriculture, Asia accounts for the highest annual water withdrawal rate globally, reaching 86% of its total withdrawal.

3. It is projected that within the next 25 years, one-third of the world’s population will experience severe water scarcity.

How many of the above statements are correct? (a) Only one (b) Only two (c) All three (d) None

Source-based Answer Explanation: All three statements are supported by the text: Agriculture is 70% worldwide, Asia accounts for 86% of its total annual water withdrawal, and the projection of severe water scarcity for one-third of the world’s population within 25 years.

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Question 6 (Water Cycle Inputs)

Which of the following components of the hydrological cycle is/are sustained by energy from the Sun?

1. Evaporation of water from the sea and the land.

2. Formation of clouds through the condensation of water vapours.

3. Transport of clouds to long distances by wind currents.

Select the correct answer using the code given below: (a) 1 only (b) 1 and 2 only (c) 2 and 3 only (d) 1, 2 and 3

Source-based Answer Explanation: The water cycle is sustained by energy from the sun, which evaporates water. Water vapours condense to form clouds. While cloud movement (3) is part of the overall cycle, the text specifically states the cycle is sustained by solar energy that causes evaporation and condensation. Since evaporation is explicitly linked to solar energy, and cloud formation (condensation) is the subsequent step, statement 1 is directly supported as being sustained by solar energy. Statements 2 and 3 describe the process following solar-driven evaporation. However, focusing strictly on what the text attributes to solar energy, it is the evaporation of water. Since condensation follows evaporation, it is intrinsically linked. Therefore, 1 and 2 are the most accurately derived mechanisms directly related to the solar energy input mentioned. Self-correction: Since the text only explicitly links Solar Energy to Evaporation (which drives the rest of the cycle), selecting 1 only is the safest answer if strict causality is required. However, UPSC often tests the sequence. Let’s rely on the explicit statement: “The water cycle in nature is sustained by energy from the sun. Solar energy evaporates water…”. Both 1 and 2 are essential parts of the cycle sustained by this energy. (d) 1, 2 and 3 encompasses the entire process described as occurring after solar energy input.

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Question 7 (Degradation and Management)

With reference to the degradation and management of water resources, consider the following statements:

1. Discharge of sewage and industrial effluents into water bodies often leads to an increase in the growth of aquatic plants and algal blooms, which can eventually cause water bodies to disappear.

2. Management of water resources primarily focuses on diverting supply from regions of scarcity to areas of surplus.

3. In urban and rural areas, rainwater infiltration can be promoted by feeding storm water or domestic drains into pits or trenches.

Which of the statements given above is/are correct? (a) 1 only (b) 1 and 3 only (c) 2 and 3 only (d) 1, 2 and 3

Source-based Answer Explanation: Statement 1 is correct; effluents cause algal blooms. Statement 2 is incorrect; management includes diverting supply from surplus to scarcity, and its overall goal is to provide adequate water without endangering the source. Statement 3 is correct; storm water can be fed into pits to filter underground and recharge aquifers.

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Question 8 (Desalination and Regional Facts)

In India, which of the following pair(s) correctly link the technology of desalination of sea water using solar energy with the state where it is currently being used?

1. Bhavnagar : Gujarat

2. Churu : Rajasthan

3. Chennai : Tamil Nadu

Select the correct answer using the code given below: (a) 1 only (b) 1 and 2 only (c) 2 and 3 only (d) 1, 2 and 3

Source-based Answer Explanation: Desalination using solar energy is being used at Bhavnagar in Gujarat and Churu in Rajasthan. Chennai/Tamil Nadu is not mentioned in the source.

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Question 9 (Water Management Techniques)

The practice of using growing algae or water hyacinth in rivers and lakes serves which of the following purposes in water management?

1. It cleans the water of pollutants like phosphates and nitrates.

2. It facilitates the process of chlorination to kill harmful germs.

3. The plants themselves can be utilized for the production of biogas.

Select the correct answer using the code given below: (a) 1 only (b) 2 and 3 only (c) 1 and 3 only (d) 1, 2 and 3

Source-based Answer Explanation: Growing algae or water hyacinth cleans the water of pollutants like phosphates and nitrates and these plants can be utilized for biogas production, serving a double purpose. Chlorination is a separate treatment process for killing germs.

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Question 10 (Hydrological Cycle Components and Inputs)

Which of the following descriptions related to the Hydrological Cycle is/are correct?

1. The circulation of water involves the atmosphere, sea, earth, and the entire living biota.

2. Evaporation from the ocean surface is the single largest source of atmospheric water vapour.

3. Precipitation includes only the liquid forms of atmospheric moisture descending to earth, such as rain and dew.

Select the correct answer using the code given below: (a) 1 only (b) 2 only (c) 1 and 2 only (d) 1, 2 and 3

Source-based Answer Explanation: Statement 1 is correct, the cycle involves the atmosphere, sea, earth, and biota. Statement 2 is correct, evaporation from the ocean is the largest source of water vapour. Statement 3 is incorrect, precipitation includes rain, snow, hail, sleet, and dew.