**Water** is a precious and essential resource for all life on Earth. World Water Day is celebrated annually on March 22nd to raise awareness about the importance of water and the need for its conservation.

A minimum of 50 litres of water per person per day is recommended by the United Nations for basic needs like drinking, washing, cooking, and hygiene. This is equivalent to about two and a half buckets of water per person daily. However, millions of people around the world, including in India, face a severe shortage of water.

Shortage of water can manifest as dry taps, long queues for collecting water, and even conflicts over water access, particularly during hot summer months. Water scarcity is a growing global concern.

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Activity 16.1

Collecting news clippings, articles, and pictures related to water shortage highlights the widespread nature of this problem and the difficulties faced by affected populations.

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How Much Water Is Available

The Earth appears blue from space primarily because a large portion of its surface is covered by water (about 71%). This vast amount of water is found in seas, oceans, rivers, lakes, ice caps, glaciers, underground, and in the atmosphere.

However, the majority of this water is **saline** (salty) ocean water, which is not directly suitable for human consumption or most uses. Only a small percentage of the total water on Earth is **freshwater**, which is suitable for human use.

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Activity 16.2

This activity uses proportional volumes to represent the distribution of water on Earth. Starting with a bucket representing all the water on Earth, a small amount is taken out to represent total freshwater, and an even smaller amount to represent usable freshwater (groundwater, surface water in lakes and rivers). The tiny volume representing readily usable freshwater reveals that despite the Earth being mostly covered in water, the amount available for our direct use is alarmingly small compared to the total volume.

The majority of freshwater is locked up in glaciers, ice caps, and permanent snow, which is not readily available.

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Forms Of Water

The total amount of water on Earth is essentially constant and is maintained through the continuous circulation of water through the **water cycle** (learned in Class VI and Chapter 14). In the water cycle, water changes between its three forms: **solid (ice/snow), liquid (water), and gas (water vapour)**, present simultaneously in different parts of the Earth.

• Solid form: Ice caps (at poles), snow-covered mountains, glaciers.
• Liquid form: Oceans, seas, lakes, rivers, groundwater.
• Gaseous form: Water vapour in the air.

The constant cycling ensures that water is a renewable resource, but this doesn't mean the usable freshwater supply is unlimited.

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Activity 16.3

Matching the numbers in a diagram representing the water cycle with the corresponding processes helps recall and understand the continuous movement of water through evaporation, transpiration, condensation, cloud formation, precipitation, infiltration (seepage into ground), runoff, and flow back to water bodies/oceans.

Access to water varies. While some places have piped water supply systems managed by civic bodies, many villages lack this, and people, including children, spend hours fetching water from sources located kilometres away, impacting children's ability to attend school regularly.

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Groundwater As An Important Source Of Water

**Groundwater** is a critical source of freshwater. It is the water found beneath the Earth's surface, filling the spaces between soil particles and cracks in rocks.

If you dig a hole in the ground, you might find the soil is moist due to the presence of water underground. As you dig deeper, you reach a level where the ground is saturated with water. The upper level of this saturated zone is called the **water table**.

The depth of the water table varies from place to place and time to time, depending on factors like rainfall and withdrawal rates. Water below the water table is groundwater. The source of groundwater is water from rain, rivers, ponds, and other surface sources that **seeps** into the ground. The process of water seeping into the ground is called **infiltration**.

Infiltration recharges the groundwater. At certain depths, groundwater is stored in layers of hard rock called **aquifers**. Water from aquifers can be accessed using tube wells or hand pumps.

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Depletion Of Water Table

The amount of groundwater remains stable when the rate of water withdrawal (pumping out) is balanced by the rate of replenishment (recharge from rainfall/infiltration). However, the **water table can go down (become depleted)** if withdrawal exceeds recharge.

Several factors contribute to the depletion of the water table:

• **Increasing Population:** Leads to higher demand for housing, infrastructure (roads, pavements), and water for construction. More construction reduces open areas for rainwater seepage.
• **Increasing Industries:** All industries use water in their production processes. The rising number of industries, often using groundwater, increases withdrawal.

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Activity 16.4

Listing familiar industries and the products obtained from them highlights the extensive use of water in industrial processes. Discussing how industrial growth impacts groundwater levels helps understand the link between industrial activity and water table depletion.

• **Agricultural Activities:** A large portion of freshwater is used for irrigation. In areas lacking canal systems, farmers rely heavily on groundwater for irrigating crops, especially with increasing pressure to produce more food for a growing population. This puts a strain on groundwater resources.
• **Scanty Rainfall:** Less rainfall means less water available for natural recharge of groundwater.
• **Deforestation:** Trees and vegetation help rainwater seep into the soil. Deforestation reduces the effective area for infiltration, hindering groundwater recharge.

The combined effect of increased consumption, reduced recharge areas, and insufficient rainfall can lead to alarmingly low water table levels in many areas.

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Distribution Of Water

Water distribution across the globe is uneven due to various factors, including variations in rainfall patterns. Some regions receive abundant rain, making them water-rich, while others, like deserts, receive very little rainfall and are water-scarce.

India, being a vast country, experiences significant variations in rainfall, leading to situations where some regions face floods due to excessive rain while others suffer from droughts due to lack of rain, sometimes simultaneously.

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Activity 16.5

Locating one's place of residence on a rainfall map of India and checking the average annual rainfall helps understand the local water availability based on precipitation levels. It also raises questions about water management if an area with sufficient rainfall still faces water shortages.

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Water Management

Effective **water management** practices are crucial to ensure water availability and reduce scarcity, even in areas with sufficient rainfall. Water wastage occurs at various levels, from civic supply systems to individual use.

Wastage in supply systems includes leaking pipes, which cause significant loss of treated water. Civic authorities are responsible for maintaining the network and preventing such leaks.

Individuals also contribute to water wastage, often unknowingly, during daily activities like brushing, bathing, shaving, and washing. Leaking taps at home are a major source of preventable water loss. Avoiding unnecessary use and fixing leaks are simple steps individuals can take.

A crucial aspect of water management is capturing and utilising rainwater. **Rainwater harvesting** (or water harvesting) involves collecting rainwater and storing it or using it to recharge groundwater. This is particularly important in areas with impervious surfaces (concrete, pavements) where natural infiltration is reduced.

Traditional methods of water storage and recharge, like **bawris** (stepwells), are being revived in some parts of India to address water shortages. These structures effectively collect rainwater, allowing it to seep into the ground and replenish groundwater sources.

In agriculture, efficient irrigation techniques can significantly reduce water usage. **Drip irrigation** is a technique where water is delivered directly to the base of plants through narrow tubing, minimising evaporation and ensuring water reaches the roots efficiently.

Case studies, like the rainwater harvesting initiative in Bhujpur, Gujarat, demonstrate how community efforts to build check-dams and harvest rainwater can successfully increase groundwater levels, make water available for irrigation, and transform dry areas.

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What Role You Can Play

Every individual can play a vital role in conserving water by adopting water-wise habits and preventing wastage.

Examples of water-wise habits:

• Turning off taps while brushing teeth or shaving.
• Using a bucket and mug for bathing instead of a shower.
• Mopping floors instead of washing them with large amounts of water.
• Fixing leaking taps promptly.
• Using water from washing vegetables or rinsing clothes for watering plants (if suitable).
• Reporting leaking taps in public places or at school.
• Educating others about the importance of water conservation.

Adopting these practices helps minimise wastage and ensures more water is available for everyone.

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Effect Of Water Scarcity On Plants

Plants are highly dependent on water for absorbing nutrients from the soil and preparing their food (photosynthesis). If water is scarce, plants cannot get the necessary nutrients and may wilt and eventually dry up. A world without plants would lead to a lack of food, oxygen (produced during photosynthesis), reduced rainfall (due to decreased transpiration), and numerous other environmental problems, potentially threatening all life on Earth. Therefore, water scarcity has severe consequences for the entire ecosystem.

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