Water: A Precious Natural Resource (PDF)

# 16 Water: A Precious Natural Resource - Use Cordova Smart Class Software on the smart board in class to explore water as a natural resource, with focus on its conservation and management. ## Existence of Life - Existence of life on the earth is possible due to its natural resources. - Any comp...

# 16 Water: A Precious Natural Resource - Use Cordova Smart Class Software on the smart board in class to explore water as a natural resource, with focus on its conservation and management. ## Existence of Life - Existence of life on the earth is possible due to its natural resources. - Any component of the earth or environment which can be utilised by human beings to fulfil their needs is known as a natural resource. - Natural resources are also called as earth resources as they are obtained from various parts of the earth - land, water, and atmosphere. ## Natural Resources - Classification - Natural resources can be divided into **inexhaustible natural resources** and **exhaustible natural resources**. ### 1. Inexhaustible Natural Resources: - Resources which are available in a large quantity and are not going to end in the future are called **inexhaustible natural resources**. - These include air, sunlight, etc. ### 2. Exhaustible Natural Resources: - Resources which are present in a limited quantity and can be finished if they are used in an uncontrolled manner are called **exhaustible natural resources**. - Ex: soil, wildlife, forest, minerals, etc. - The exhaustible natural resources which can be replenished within a reasonable time are called **renewable natural resources**. - For example, soil, forest, and underground water. - The exhaustible natural resources which cannot be replenished within a reasonable time are called **non-renewable natural resources**. - Ex: fossil fuels like petroleum and coal. ## Uses of Water - Water is essential for the existence of life. ### Life Processes: - Life processes such as digestion, distribution of nutrients and excretion require water. ### Body Temperature: - Water helps in maintaining the temperature of our body by sweating. ### Daily Activities: - It is required for daily routine activities such as drinking, cooking, and cleaning utensils. ### Electricity Generation: - It is also useful in the generation of electricity, navigation, and irrigation. ### Habitat: - For several plants and animals, water acts as a habitat. ### Plants Growth: - Water helps in the germination of seeds, and growth of plants. - Water is required by plants during the process of photosynthesis. - It also helps in the transport of minerals and nutrients from the soil to the different parts of the plant. ## Availability of Water in Nature - When we look at the picture of the earth taken from space, much of its part appears blue. - This is because about 71% of the earth's surface is covered with water. - Therefore, our earth is also called a watery planet. ### Water Distribution: - Almost 97.5% of the water available on the earth's surface is contained in the seas and oceans. - This water is salty or saline which cannot be consumed directly and therefore is unfit for human consumption. - Of the remaining 2.5%, a major portion (1.7%) is found in the frozen form as ice caps on the top of the mountains and in glaciers. - Only 0.8% of total water on earth is fresh water, available as river water, lake water, and groundwater, and is fit for use for human beings. - So, we can say that the actual amount of water available for human use is negligible. ## Forms of Water - We know that water exists in three physical states - **solid, liquid, and gas** under different conditions. - These states of matter can be interconverted by heating or cooling. - Water can be found in all the three forms at any given time on the earth. ### 1. Solid Form: - The solid form of water, i.e., snow and ice, is present as ice caps at the poles of the earth, snow-covered mountains, and glaciers. ### 2. Liquid Form: - Liquid form of water is present in oceans, lakes, rivers, and even as underground water. ### 3. Gaseous Form: - The gaseous form of water, i.e., water vapour, is present in the air around us. - The continuous circulation of water among its three forms keeps the total amount of water on the earth constant, even when the whole world is using it for millions of years. ## Water Cycle - We know that the continuous circulation of water from the earth's surface and water bodies as water vapour to the atmosphere and from the atmosphere back to the earth's surface as rain, hail and snow is called the **water cycle** in nature. - The water on the earth has been maintained for millions of years by various processes which make the water cycle. ## Where Do We Get Water From? - Most towns and cities have a water supply system maintained by the civic bodies. - The water is drawn from nearby lakes, rivers, ponds, or wells. - Water from natural sources contains many impurities. - These impurities are removed to make it suitable for drinking. ### Water Purification Process: - Sedimentation, filtration, aeration, and chlorination are various steps involved in the purification of water obtained from natural sources. - Then we get purified river or lake water in our taps through a network of pipes. - Many villages do not have such a water supply system. - There, people fetch water directly from the sources. - A large number of people draw water from wells, tube wells, or hand-pumps. - **Most of the ancient civilisations flourished in the plains of rivers because water was easily available for various purposes.** ## Science Update: - Getting clean water, money out of sewage: The Indian Agricultural Research Institute has successfully installed a purification system for their homes in Pusa, Delhi that can clean 2.2 million litres of domestic sewage daily using almost zero thermal power. - The water *(free from chemicals)* can be used for gardening and irrigation. - The system is based on nature's ways. - The dirty water is collected and flown through an array of wetland plants with capacity to absorb chemicals such as lead and mercury upto 1,000 parts per million *(ppm)*. - Apart from assured agricultural income, the wetland plants can be harvested for a revenue of about 20 lakh annually. ## Groundwater as an Important Source of Water: - When we dig a deep hole in the ground, we find moist soil. - It shows the presence of water under the ground. - If we keep on digging further deep inside, we will reach a level where all the spaces between the soil particles and gap between the rocks are filled with water. - From where does this water come from? ### Water Infiltration: - The rainwater and water from other sources such as rivers, lakes, and ponds steep through the soil and fill the empty spaces and cracks below the ground. - The process of seeping of water into the ground is called infiltration. - After saturating the soil, rainwater and water from other sources move downwards and get collected above impervious rocks *(we know impervious rocks do not allow water to pass through them)*. - This reservoir of water collected above impervious rocks below the surface of the earth is called **groundwater**. ### Water Table Definition: - The upper limit of groundwater is called the **water table** *(Fig. 16.4)*, or it may be defined as the minimum depth in the soil where all the pore spaces are filled with water. ### Water Table Variation: 1. - The water table varies from place to place and it may even change at a given place. 2. - The water table may be at a depth of less than a metre or may be several metres below the surface of earth. 3. - Water table falls during summers and rises during rainy season. ### Groundwater Filtration: - Groundwater gets filtered by several layers of sand and rocks when passed through the soil. - Thus, it is almost free from suspended impurities but contains dissolved salts. - The huge reservoirs of water inside the earth, formed by the collection of groundwater between the layers of hard rocks below the water table, are known **aquifers**. ### Water Table Extraction: - Traditionally, groundwater has been utilised by digging wells deep till it reaches the water table. - Manually operated hand-pumps or power operated tube wells are also used to pump out the groundwater. - This groundwater is used for household *(domestic)*, agricultural, and industrial purposes. - Groundwater provides moisture to the soil which helps in the proper growth of plants. ### Groundwater Depletion: - The gradual and continuous lowering of the water table is known as **groundwater depletion**. - It is also known as depletion of the water table.. ## Depletion of Water Table - The water which we draw *(or take out) from the ground for various purposes gets replenished naturally by the seepage of rainwater*. - The water table at a place does not get affected as long as we draw as much water as is replenished by natural processes. - However, in many areas, the water table may go down if the groundwater is being used at a faster rate than it is being replenished by the natural processes. ### Factors Contributing to Water Table Depletion: 1. **Increase in Population:** Human population is increasing day by day. To meet the needs of an ever-increasing human population, more houses, offices, schools, shops, and roads are being built. These construction activities need a huge supply of water. So, borings are made at such construction sites to reach the water table and to draw more and more groundwater. This causes the depletion of the water table. 2. **Increase in Industries:** The number of industries is increasing continuously which draws a huge quantity of water from the ground leading to the depletion of the water table. 3. **Increase in Agricultural Activities:** With increase in population, the demand for food has increased manifold. A majority of farmers depend on rainwater to grow crops. But due to unpredictable rainfall, they depend on irrigation methods. In many places, the canal system may suffer from the lack of water due to erratic rainfall. Nowadays, farmers use large quantities of groundwater by digging deep tube wells to cultivate crops. This results in depletion of the water table. 4. **Deforestation:** Cutting down a large number of trees at a place is called **deforestation**. This leads to failure of soil to hold moisture. The water just runs off on the ground surface. Cherrapunji *(Meghalaya)*, which is one of the places that receive the highest amount of rainfall in the world, faces a shortage of water because rain runs off fast down the deforested mountain slopes. 5. **Decrease in the Effective Area for Seepage of Water:** We have discussed that increasing population creates more demand for construction of houses, shops, offices, roads, etc. This decreases the open areas like parks, playgrounds, and other open spaces. The cemented floor does not allow water to seep in the ground easily. This results in depletion of the water table. 6. **Scanty Rainfall:** India is a vast country and the rainfall is not the same everywhere. Some regions have excessive rains while some others have very little rainfall. Excessive rains cause floods, whereas the absence of rains results in droughts. Some regions like Rajasthan, Northern Karnataka, Kutch in Gujarat, and Odisha are prone to drought. On the whole, about 18% of our country is drought prone. Besides, rainfall is not even every year. Sometimes, the rainfall is far less than the average rainfall. **'Insufficient rainfall'** is called **scanty rainfall**. When there is scanty rainfall, less water seeps into the ground. In such a situation, much more groundwater is drawn out by the people for various purposes that gets replenished by rainfall. This results in depletion of the water table. ## Water Management - Every year, 22nd March is celebrated as the **World Water Day**. - We celebrate this day to attract everybody's attention towards the importance of conserving water. - There is a general consensus that for satisfying individual's personal and domestic needs such as drinking, washing, cooking, and maintaining proper hygiene, water requirement is about 50 litres per capita per day *(per person per day)*. - Today, the world is heading towards a water crisis. - According to a recent United Nations report, the supply of clean and fresh water is depleting at such an alarming rate that in some regions, within 30 years, about two-thirds of population will suffer a moderate to severe water crisis. - A water crisis is defined as the situation where there is a fall in the availability of usable water such that there is insufficient water to satisfy normal requirements. - It is also known as water scarcity. - We often face water scarcity during the summer seasons. - As a result, the municipal water supply is restricted. - Our wells and hand-pumps get dried resulting into a water crisis. - Due to this, we see long queues for water *(Fig. 16.6)*, fights, marches, and protests for demand of water, at some places especially during summers. - Such frequent situations of water crisis alarm us to conserve water and prevent it *misuse*. ### Rainwater Harvesting - One way of increasing the availability of water to overcome its shortage is **rainwater harvesting**. - The process of collecting rainwater from roofs and street corners and storing it for later use is called rainwater harvesting *(Fig. 16.7)*. - In this method, water is collected in percolation pits and recharge wells so as to recharge groundwater. - This is an ideal solution to water problem in areas with inadequate water resources. ### Advantages of Rainwater Harvesting: - The water table can be raised by rainwater harvesting. - It reduces the runoff loss of rainwater. - Availability of water supply for irrigation and other purposes is also maintained in dry months. - It reduces flood and topsoil erosion. - It reduces strain on other modes of water supply. - It increases the availability of clean water. ## Prevention of Wastage of Water: - The wastage of water in households, commercial buildings, schools, and public places can be prevented by closing taps when not in use, repairing any leakage from pipes, etc. ## Reuse of Water: - The treated wastewater can be used for watering lawns and gardens, washing vehicles, and floors, and for construction purposes. - It helps in saving fresh water. ## Revival of Bawris: - At many places in India, we have an age-old practice of water storage and water recharge system like the **bawris** *(Fig. 16.8)*. - Bawri is a step-well in which the rainwater is collected and stored. - It provides water to the people during drought periods. - Due to the acute water shortage faced by the people in some places, the bawris are being renovated and revived. ## Drip Irrigation: - Plants need sufficient water to grow. - Plants absorb water through the roots. - **Drip irrigation** is a technique of watering plants by making use of a system of narrow pipes or tubes with small holes which deliver the water drop by drop directly around the roots *(Fig. 16.9 (a) and (b))* . - Thus, wastage of water is avoided. - This system allows the farmers to produce a high yield with very little water. ## Construction of Dams: - An artificial wall built across a river which allows the water to collect behind it in a reservoir is known as a **dam** *(Fig. 16.10)*. - A system of artificial canals channelises water from the reservoir to the region downstream for irrigation. - Rainwater or river water can be prevented from flowing away by constructing dams. - The dams control floods, provide water for irrigation, industries, solve drinking water problem especially during summer seasons, generate electricity, etc. ## Care for Environment: - We can save water at home by minimising its wastage in the following ways: - Do not keep the tap open while brushing teeth, washing hands, or cleaning utensils. - Collect rainwater in drums and use it to water the plants. - Use a bucket and a mug instead of using a shower for a bath. - Get leaking pipelines and leaking water taps repaired. - Clean your vehicle with a wet cloth instead of washing with running water. - Mop the floor instead of washing with running water. - Use water left in your bottle for watering the plants or cleaning the vehicles. - Do not throw it. - Do not hose down your driveway or sidewalk. - Use a broom to clean leaves and debris from these areas. ## Case Study: - A place called **Bhujpur** in the Kutch area of Gujarat has very erratic rainfall. - The rivers of this area are dry most of the time of the year. - People depend on the underground water as the only freshwater resource. - The withdrawal of groundwater in this area has exceeded the recharge and thus, the water table has gone down alarmingly. - In the year 1989, the villagers of Bhujpur with a non-government organisation decided to harvest rainwater. - They built 18 check dams on Rukmavati river and its tributaries. - The collected water percolated into the ground and recharge the aquifers. - This has resulted in the presence of water in wells and availability of water for irrigation. ## Some Inspiring Initiatives: - 1000 check dams were constructed in Jhabua district of Madhya Pradesh which has increased food production by about 40% in the past 5 years. - Saurashtra Lok Manch of drought hit district of Rajkot *(Gujarat)* initiated the project of rooftop rainwater harvesting and recharging of wells and has been successful in preventing drying up of wells. - A band of social workers has transformed a dry area in the Alwar district *(Rajasthan)* into a green place, by reviving five dried-up rivers - Arveri, Ruparel, Sarsa, Bhagani and Jahazwali by constructing water harvesting structures. ## Effects of Water Scarcity: 1. **Non-availability of Food:** The plants cannot carry out the process of photosynthesis without water. - They cannot make food for themselves. - Animals directly or indirectly depend on plants for food. - Without plants, animals will also have no food. 2. **Non-availability of Oxygen:** We know that oxygen gas is released in the process of photosynthesis *(which requires water)*. - Without photosynthesis, no oxygen will be released by green plants and hence, no oxygen will be available to animals and humans for breathing. 3. **Less Rainfall:** Trees and green plants release a lot of water vapour into the atmosphere through transpiration. - This water vapour helps in the formation of clouds in the water cycle. - Trees in the forest help in bringing rain. - The deforested area receives less rainfall. ## Concept Map for Revision - Water: A Precious Natural Resource - The concept map is a visual representation of the key ideas and connections related to the topic "Water: A Precious Natural Resource". - It covers the importance of water, its forms, effects of water scarcity, and water management techniques. ## Exercise - The exercise section provides a variety of questions to assess the student's understanding of the topic. - It includes oral questions, science quiz, worksheet, very short answer questions, short answer questions, long answer questions, HOTS questions, and an activity. ### Section A - This section consists of oral questions, a science quiz, and a worksheet. - The oral questions test the student's basic understanding of the topic. - The science quiz tests the student's knowledge of specific facts and concepts. - The worksheet provides exercises to reinforce the student's understanding of key concepts. ### Section B - This section includes multiple-choice questions, very short answer questions, short answer questions, and long answer questions. - These questions are designed to assess the student's ability to apply their knowledge to real-world scenarios. ### Section C - This section contains HOTS *(Higher Order Thinking Skills)* questions. - These questions challenge the student to think critically and creatively. - They require the student to analyze information, solve problems, and make connections between different concepts. ### Activity - The activity section encourages the student to engage in hands-on learning. - The activities are designed to help the student develop a deeper understanding of the topic and its real-world applications. ## NCRET Exemplar: - This section presents an example of a NCERT Exemplar question. - The questions test the student's understanding of key concepts and their ability to apply those concepts to new situations. ## Home Assignment/Group Activity/Project - This section provides suggestions for additional activities that the student can do outside of the classroom. - These activities can help the student to apply their knowledge to real-world scenarios and to further their understanding of the topic. ## Field Visit - This section suggests a field visit to help the student learn more about the topic. - Field visits provide students with a hands-on learning experience that can help them to better understand the concepts. ## Group Discussion - This section encourages students to engage in group discussions about the topic. - Group discussions can help students to develop their critical thinking skills and to share their ideas and perspectives. ## For Live Test Paper login to www.cordovajoyfullearning.com - This section provides a link to a website where students can find additional resources and practice tests for the topic. - This is a summary of the content in the provided document. - It includes key information about the topic, as well as examples of questions and activities that can help students to learn more about the importance and management of water.