Water Resources (Class 10): Notes और MCQ Practice

आसान भाषा में

Earth पर 71% पानी होने के बावजूद usable Freshwater बहुत सीमित है। बढ़ती population, over-exploitation और pollution की वजह से Water Scarcity बढ़ रही है। इस chapter में हम Multi-Purpose River Projects (Dams) के फायदे-नुकसान और Rainwater Harvesting के smart techniques को समझते हैं।

Important Points & Definitions

• Water Scarcity के कारण: Over-exploitation, excessive use, unequal access, urbanisation और industrial pollution.
• Multi-Purpose Projects (Dams): Jawaharlal Nehru ने इन्हें 'Temples of modern India' कहा था क्योंकि ये agriculture और industrial development को साथ जोड़ते हैं।
• Fayde: Irrigation, Hydroelectricity generation, flood control, fish breeding.
• Nuksan: Displacement of communities, loss of flora-fauna, siltation, interstate water disputes (e.g., Krishna-Godavari dispute).
• Social Movements: Dams के विरोध में बड़े protests हुए—जैसे Narmada Bachao Andolan (Sardar Sarovar Dam) और Tehri Dam Andolan.
• Traditional Rainwater Harvesting:
• Guls / Kuls: Western Himalayas में diversion channels.
• Khadins (Jaisalmer) & Johads (parts of Rajasthan): Agriculture fields में पानी रोकने वाले structures.
• Tankas: Bikaner, Phalodi और Barmer में underground drinking water tanks.
• Bamboo Drip Irrigation: Meghalaya में 200 साल पुरानी 18-20 लीटर पानी transport करने की technique.
• Tamil Nadu: भारत का पहला राज्य जहाँ हर घर में Rooftop Rainwater Harvesting legally compulsory है।

2 Memory Tricks

1. G-H-B-M (Geography Connections): Guls = Himalayas | Bamboo Drip = Meghalaya.
2. TN = Top Nation (Rule-maker): Tamil Nadu पहला state है जिसने rooftop harvesting mandatory (compulsory) किया।

2 Common Board-Exam Mistakes

1. Scarcity का अधूरा reason लिखना: Students सोचते हैं कि water scarcity सिर्फ कम बारिश की वजह से होती है। Board exams में over-use, bad water quality (pollution) और unequal access ज़रूर लिखें।
2. Dams के negative impacts भूल जाना: केवल electricity और irrigation लिखने से full marks नहीं मिलते; ecological damage और tribal displacement का point लिखना अनिवार्य है।

Water Resources

1. Chapter in Short

Water is an essential natural resource that is renewable through the hydrological cycle. Even though three-fourths of the Earth's surface is covered with water, only a tiny fraction (about 2.5%) is freshwater.

This chapter discusses:

• Why water scarcity occurs even in areas with plenty of rainfall.
• The need to conserve and manage water resources.
• Multi-Purpose River Valley Projects: Their benefits and the environmental and social issues they create.
• Rainwater Harvesting: Eco-friendly, cost-effective traditional and modern methods of conserving water across different regions of India.

2. Key Concepts Explained Simply

A. Water: A Renewable Resource

Water constantly moves through evaporation, condensation, and precipitation. This cycle is called the hydrological cycle. Because of this cycle, water is continuously renewed.

B. Water Scarcity and Its Causes

Water scarcity means a shortage of water. It does not only happen in dry deserts; it can happen anywhere.

• Quantitative Scarcity (Lack of quantity): Caused by rapid population growth (higher demand for food leads to over-irrigation using tube wells), expanding industries (heavy users of water and power), and urban lifestyles.
• Qualitative Scarcity (Poor quality): Even if water is available in large amounts, it may be polluted by domestic sewage, industrial waste, pesticides, and fertilizers, making it unfit for human use.

Everyday Example: Think of having a full water bottle, but someone poured ink into it. You have water, but you cannot drink it. That is qualitative water scarcity.

C. Multi-Purpose River Projects

A dam is a barrier built across flowing water that obstructs, directs, or slows down the flow, creating a reservoir or lake. When a project serves several goals at the same time, it is called a Multi-Purpose Project.

• Benefits: Irrigation, electricity generation, flood control, water supply for drinking and industries, inland navigation, and fish breeding.
• Why Nehru called them "Temples of Modern India": Jawaharlal Nehru believed these projects would integrate the development of agriculture with rapid industrialization and urban growth.

D. Why Are Large Dams Criticized?

In recent years, mega-dams have faced strong opposition (e.g., Narmada Bachao Andolan and Tehri Dam Andolan) because:

1. Ecological Damage: Regulating river flow disrupts aquatic habitats and blocks natural sediment (silt) flow, leading to rocky stream beds and poorer soil fertility downstream.
2. Submergence: Large reservoirs submerge forests and agricultural land, leading to soil decomposition.
3. Displacement: Local communities lose their ancestral land, livelihoods, and access to resources.
4. Inter-State Disputes: Sharing river water causes conflicts between states (e.g., the Krishna-Godavari dispute between Karnataka and Andhra Pradesh).
5. Induced Disasters: Excessive sedimentation can cause floods during heavy rains instead of controlling them, and large reservoirs can trigger earthquakes.

E. Rainwater Harvesting

Rainwater harvesting is a sustainable, eco-friendly alternative to large dams. Different regions of India have evolved traditional systems:

• Western Himalayas: People built diversion channels called guls or kuls for agriculture.
• Arid/Semi-Arid Rajasthan:
• Agricultural fields were converted into rain-fed storage structures called khadins (in Jaisalmer) and johads (in other areas).
• Houses built underground storage tanks called tankas inside courtyards to store rainwater (Palar pani) collected from rooftops.
• Bengal: Inundation channels were dug to irrigate fields using floodwater.
• Meghalaya: A 200-year-old system called Bamboo Drip Irrigation transports stream and spring water using bamboo pipes to water crops.

3. Important Definitions, Facts, and Dates

• Hydrological Cycle: The natural journey of water from the Earth to the atmosphere and back through evaporation, condensation, and precipitation.
• Dam: A barrier across flowing water that restricts flow and creates a reservoir.
• Palar Pani: The local Rajasthani term for pure rainwater, considered the purest form of natural water.
• Guls / Kuls: Diversion channels built in hilly and mountainous regions (Western Himalayas) for irrigation.
• Tankas: Underground tanks built inside houses in semi-arid parts of Rajasthan (Bikaner, Phalodi, Barmer) to store rooftop rainwater.

Key Facts to Remember:

• 96.5% of the world's total water is in oceans and seas; only 2.5% is freshwater.
• Nearly 70% of freshwater is locked in ice sheets and glaciers (Antarctica, Greenland, Himalayas); less than 30% is groundwater.
• India receives about 4% of global precipitation and ranks 133 in the world in terms of water availability per person per year.
• By 2025, it is predicted that large parts of India will join countries facing absolute water scarcity.
• Sringaverapura (near Prayagraj/Allahabad): Had a sophisticated water harvesting system channeling the floodwaters of the Ganga as early as the 1st century B.C.
• Tamil Nadu: The first state in India to make rooftop rainwater harvesting compulsory for all houses by law. Defaulters face legal punishment.
• Gendathur (Mysuru, Karnataka): A remote village that earned fame for installing rooftop rainwater harvesting in nearly 200 households.

4. Board-Exam Style Questions with Answers

Question 1: What is water scarcity? State two quantitative and two qualitative reasons for water scarcity in India.

Answer:

Water scarcity is the lack of sufficient available water resources to meet the demands of water usage in a region.

• Quantitative Causes:

1. Growing Population: Large population requires more water for domestic use and food production, leading to over-extraction of groundwater through tube wells.
2. Industrial Expansion: Heavy industries use enormous amounts of water for processing and consume hydroelectricity.

• Qualitative Causes:

1. Pollution by Sewage: Untreated domestic sewage dumped directly into rivers and ponds makes water unusable.
2. Agricultural Chemicals: Chemical fertilizers and pesticides seep into water bodies and groundwater, poisoning water sources.

Question 2: Why did Jawaharlal Nehru proclaim dams as the "Temples of Modern India"? Give two reasons.

Answer:

Jawaharlal Nehru called multi-purpose river valley projects the "Temples of Modern India" because:

1. They were expected to combine the development of agriculture (through canal irrigation) with the growth of village industries.
2. They would support rapid industrialization and the expansion of the urban economy by providing cheap hydroelectric power and domestic/industrial water supply.

Question 3: Explain three major disadvantages or criticisms of multi-purpose river valley projects.

Answer:

1. Destruction of River Ecology: Damming alters the natural flow of rivers and causes excessive sediment buildup in reservoirs. This makes stream beds rocky and harms the breeding and movement of aquatic life.
2. Displacement of Local People: Building large dams drowns vast areas of land, displacing local communities and tribals from their homes and farms without proper rehabilitation.
3. Failure to Control Floods and Environmental Hazards: Sedimentation in the reservoirs reduces their water-holding capacity, which has sometimes triggered severe floods during heavy rainfall. Mega-dams have also been linked to induced earthquakes and water-borne diseases.

Question 4: How was rooftop rainwater harvesting traditionally practiced in the semi-arid regions of Rajasthan?

Answer:

In semi-arid regions like Bikaner, Phalodi, and Barmer, rooftop rainwater harvesting was practiced using underground tanks called tankas:

1. Tankas were large underground rooms built inside the courtyard or house.
2. Sloping roofs of houses were connected to the tanka through pipes.
3. Rain falling on the roofs flowed through the pipes into the tanka.
4. The first spell of rain was usually not collected as it cleaned the roof and pipes; subsequent rain was stored.
5. This collected water (Palar pani) was sealed and kept clean, serving as a reliable drinking water source during dry summers.

5. Common Mistakes and Quick Revision Points

Common Mistakes:

• Mistake: Assuming water scarcity only happens in desert regions with low rainfall.

Correction: High-rainfall areas can also face water scarcity due to over-exploitation, mismanagement, and water pollution.

• Mistake: Mixing up regional water harvesting terms.

Correction: Remember:

• Guls / Kuls = Western Himalayas (hills)
• Khadins and Johads = Rajasthan (agricultural fields)
• Tankas = Rajasthan (underground household tanks)
• Inundation channels = Flood plains of Bengal
• Bamboo drip system = Meghalaya
• Mistake: Confusing the roles of Gendathur and Tamil Nadu.

Correction: Tamil Nadu is the state that legally mandated rooftop rainwater harvesting. Gendathur is a village in Karnataka famous for community-level rooftop harvesting.

Quick Revision Points:

• 96.5% ocean water + 2.5% freshwater.
• India ranks 133 in per capita water availability; absolute scarcity projected by 2025.
• Dams = Multipurpose (irrigation, power, flood control), but cause ecological harm and displacement.
• Major movements against dams: Narmada Bachao Andolan (Sardar Sarovar Dam) and Tehri Dam Andolan (Tehri Dam).
• Traditional rainwater harvesting is eco-friendly, cost-effective, and sustainable.