Causes of Water Scarcity

1. Low Rainfall and Irregular Precipitation: Insufficient and irregular rainfall often leads
to drought-like conditions.
2. Over-Exploitation and Unequal Access: Excessive use and unequal distribution of
water among different social groups contribute to scarcity.
3. Growing Population: A large and growing population increases the demand for water
for domestic purposes.
4. Industrialization: Rapid industrial growth requires significant amounts of water and
energy, much of which comes from hydroelectric power, further straining water
resources.
5. Urbanization: Expansion of cities after independence has led to higher water
consumption, worsening scarcity.
6. Water Pollution: Pollution from domestic waste, industrial discharge, and agricultural
chemicals contaminates available water, making it unusable.
7. Agricultural Needs: Large-scale farming to feed the population requires heavy water
use for irrigation, especially during dry seasons.

Need for Water Conservation and Management

1. Meeting Water Demand: Proper management ensures sufficient water for various
needs, including domestic, industrial, and agricultural use.
2. Protecting Public Health: Effective water conservation helps prevent health issues
caused by toxic, contaminated water.
3. Ensuring Food Security: Water management is vital for irrigating crops and maintaining
agricultural productivity, which ensures a stable food supply.
4. Supporting Livelihoods: Water conservation ensures continued access to water for
work, farming, and other productive activities.
5. Protecting Ecosystems: Managing water resources helps preserve natural ecosystems
and biodiversity by preventing overuse and pollution.
6. Revolutionizing Agriculture: Since irrigation is the largest consumer of water, there is a
need for drought-resistant crops and dry farming techniques to reduce water demand.

Hydraulic Structures in Ancient India

1. Sringaverapura (1st Century BC): A water harvesting system was developed to

channel floodwaters of the Ganga river near Allahabad.
2. Chandragupta Maurya's Era: During his reign, extensive construction of dams, lakes,
and irrigation systems took place.
3. Irrigation Works in Various Regions: Evidence of irrigation systems has been found in
places like Kalinga (Odisha), Nagarjunakonda (Andhra Pradesh), Bennur (Karnataka),
and Kolhapur (Maharashtra).
4. Bhopal Lake (11th Century): One of the largest artificial lakes of its time was built in the
11th century.
 5. Hauz Khas Tank (14th Century): Iltutmish built a tank in Delhi to supply water to the Siri
Fort area.

● Jawaharlal Nehru proudly proclaimed the dams as the ‘temples of modern India’;
the reason being that it would integrate development of agriculture and the village
economy with rapid industrialisation and growth of the urban economy.

Dam:

Definition and Function: A dam is a structure built across flowing water to block or control its
flow, creating reservoirs or lakes. It typically includes a spillway or weir to manage water flow.

Classification by Structure: Dams are classified into timber dams (wood), embankment
dams (earth or rock), and masonry dams (stone or brick), based on the materials used.

Classification by Height: Dams are categorized by height into low dams (under 15m),
medium dams (15-30m), and high dams (over 30m), with larger dams having more significant
impacts.

Dams Role in Water Conservation and Management

1. Irrigation: Traditionally, dams were built to store rainwater and river water, which could
later be used for irrigating agricultural fields, ensuring a steady water supply for crops.
2. Electricity Generation: Dams are also used for generating hydroelectric power,
providing a renewable source of energy.
3. Water Supply: Dams supply water for domestic use (drinking, cooking, sanitation) and
industrial purposes, ensuring reliable access to water in urban and rural areas.
4. Flood Control: By controlling the flow of water, dams help prevent floods, especially
during periods of heavy rainfall or snowmelt.
5. Recreation and Navigation: Dams create reservoirs that are often used for recreational
activities like boating and fishing. They also facilitate inland navigation by controlling
water levels.
6. Fish Breeding: Some dams are designed to support fish breeding, helping maintain
biodiversity and support the fishing industry.

Adverse Effects and Limitations of Multi-Purpose Projects

1. Impact on Soil Fertility: Reservoirs submerge vegetation and soil, leading to

decomposition over time, which reduces soil fertility.
2. Displacement of Communities: Large-scale river projects displace local communities,
affecting their livelihoods, homes, and cultural heritage.
3. Harm to Aquatic Life: Dams obstruct the natural flow of rivers, making it difficult for
aquatic species like fish to migrate and spawn.
 4. Ecological Imbalance: Irrigation from dams encourages water-intensive farming and
commercial crops, leading to soil salinization and other ecological problems.
5. Sedimentation and Flood Risk: Dams reduce natural sediment flow, causing sediment
to accumulate at the reservoir's bottom. This raises water levels, increases flood risk,
and leads to rocky streambeds.
6. Other Hazards: Multi-purpose projects have been linked to induced earthquakes,
waterborne diseases, pest infestations, and pollution caused by excessive water usage.

Rainwater Harvesting: A Solution to Water Wastage

Rainwater harvesting is a sustainable method to store and utilize rainwater instead of letting it
drain away. This practice helps reduce water scarcity, recharge groundwater, and ensure a
reliable water supply. Here are some of the key rainwater harvesting methods used in India:

1. Guls or Kuls (Western Himalayas): Diversion channels built to direct mountain stream
water towards fields for irrigation.
2. Rooftop Rainwater Harvesting (Rajasthan): Rainwater collected from rooftops is
channeled into tankas (underground tanks) for drinking and domestic use. Other
techniques like khadins (in Jaisalmer) and johads (in parts of Rajasthan) help store
rainwater for irrigation and soil moisture.
3. Inundation Channels (West Bengal): Channels are built to capture and store flood
water from rivers, which is later used for irrigation.
4. Rainwater Harvesting (Meghalaya): With abundant rainfall, Meghalaya has traditional
methods to collect rainwater for household and agricultural use. Bamboo Drip
irrigation- Bamboo pipes direct rainwater to farms.
5. Modern Housing and Construction: Modern buildings and housing societies now
incorporate rainwater harvesting systems to store rainwater in underground tanks or
recharge groundwater, reducing dependence on municipal water supply.

Important Dams:
1. Salal (Chenab – Jammu & Kashmir)
2. Bhakra Nangal (Sutlej – Himachal Pradesh)
3. Tehri (Bhagirathi – Uttarakhand)
4. Rana Pratap Sagar (Chambal – Rajasthan)
5. Sardar Sarovar (Narmada – Gujarat)
6. Hirakud (Mahanadi – Orissa)
7. Nagarjuna Sagar (Krishna – Telangana & A.P.)
8. Tungabhadra (Tungabhadra – Karnataka)
Increased Demand: A growing population requires more water for domestic, agricultural, and
industrial use, leading to over-extraction of water resources.
Urbanization: Expanding cities reduce groundwater recharge due to concrete surfaces and
increase water demand, worsening scarcity.
Agricultural Pressure: A larger population needs more food, increasing irrigation requirements
and overusing water sources.

● Narmada Bachao Andolan or Save Narmada Movement is an NGO. It originally focused

on the environmental issues related to trees that would be submerged under the dam
water. The NGO came forward with many environmentalists, tribal people, farmers and
social activists demanding poor rehabilitation and ecological protection.
● Massive displacement in the Tehri Dam Project on Bhagirathi also caused many social
movements like Tehri Dam Andolan.
● The Rihand Valley Project over Son river in Uttar Pradesh created massive displacement
due to which it is facing public agitation.

Increased Demand: Growing urban populations and industries consume excessive water,
depleting available resources.
Reduced Groundwater Recharge: Concrete surfaces in cities prevent rainwater from seeping
into the ground, leading to groundwater shortages.

Q11 is the most asked ques: learn it properly

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● Rooftop rainwater harvesting is the most common practice in Shillong,
Meghalaya. It is interesting because Cherrapunji and Mawsynram situated at a
distance of 55 km. from Shillong receive the highest rainfall in the world, yet the
state capital Shillong faces acute shortage of water. Nearly every household in the
city has a rooftop rainwater harvesting structure. Nearly 15-25 per cent of the total
water requirement of the household comes from rooftop water harvesting.
● Tamil Nadu is the first state in India which has made rooftop rainwater harvesting
structure compulsory to all the houses across the state. There are legal provisions
to punish the defaulters.