This MCQ module is based on: Multi-Purpose Projects & Rainwater Harvesting Class 10 NCERT Geography Ch 3 Part 2
Multi-Purpose Projects & Rainwater Harvesting Class 10 NCERT Geography Ch 3 Part 2
Multi-Purpose Projects & Rainwater Harvesting
NCERT Contemporary India-II | Chapter 3: Water Resources
What Is India's Long Tradition of Water Conservation?
How do we conserve and manage our precious water resources? Archaeological and historical records reveal that India has a rich heritage of constructing sophisticated hydraulic structures? since ancient times. Stone-rubble dams, reservoirs, lakes, embankments, and canals for irrigation were built by our ancestors, reflecting deep knowledge of water management. This tradition has continued into modern India through the construction of dams across most river basins.
What Are Multi-Purpose River Projects and How Do They Work?
Traditionally, dams? were built primarily to store river and rainwater for later use in irrigating agricultural fields. In modern India, however, dams serve multiple purposes simultaneously. They generate electricity, supply water for domestic and industrial needs, control floods, support inland navigation, provide recreation facilities, and enable fish breeding. Because a single dam project integrates so many functions, these are called multi-purpose projects?.
Key Examples of Multi-Purpose Projects
| Project | River / Basin | Key Functions |
|---|---|---|
| Bhakra-Nangal | Sutlej-Beas Basin | Hydroelectric power generation and irrigation |
| Hirakud Dam | Mahanadi Basin | Water conservation integrated with flood control |
| Sardar Sarovar | Narmada River | Irrigation for drought-prone areas in Gujarat, Rajasthan, Maharashtra; covers 18.45 lakh hectare in Gujarat alone |
After independence, multi-purpose projects with their integrated water resources management approach were seen as engines of national development. Jawaharlal Nehru famously referred to dams as the vehicles that would integrate agricultural growth in villages with rapid industrialisation in cities, helping India overcome the handicaps of its colonial past.
Why Is There Opposition to Multi-Purpose Dam Projects?
In recent decades, large dams and multi-purpose projects have faced growing scrutiny and resistance. The concerns are both environmental and social:
Further criticisms include: sedimentation depriving downstream floodplains of natural silt (a free fertiliser), leading to land degradation; multi-purpose projects inducing earthquakes in some cases; water-borne diseases and pest infestations arising from large stagnant reservoirs; and changes in cropping patterns, with farmers shifting to water-intensive commercial crops, causing ecological problems like soil salinisation?.
How Does Rainwater Harvesting Work as a Water Conservation Method?
Given the disadvantages of large dams and growing resistance to them, many experts have advocated rainwater harvesting? as a socio-economically and environmentally sound alternative. India has an extraordinary tradition of water harvesting systems that date back centuries. Communities possessed deep knowledge of local rainfall patterns and soil types, and developed diverse techniques to capture rainwater, groundwater, river water, and floodwater suited to their specific ecological conditions.
Traditional Rainwater Harvesting Methods Across India
| Region | Method | Description |
|---|---|---|
| Western Himalayas | Guls / Kuls | Diversion channels that redirect stream water for agricultural use in hilly terrain |
| Rajasthan (arid areas) | Rooftop harvesting into Tankas | Underground tanks connected to sloping rooftops through pipes, storing drinking water |
| Jaisalmer, Rajasthan | Khadins | Agricultural fields converted into rain-fed storage to moisten the soil in arid zones |
| Other parts of Rajasthan | Johads | Earthen check dams that capture and store rainwater to recharge groundwater |
| Bengal (flood plains) | Inundation channels | Channels that divert floodwater to irrigate agricultural fields |
| Meghalaya | Bamboo drip irrigation | A 200-year-old system using bamboo pipes to transport 18-20 litres of spring water, reducing flow to 20-80 drops per minute at the plant |
Tankas of Rajasthan — A Detailed Look
In the semi-arid and arid regions of Rajasthan — particularly in Bikaner, Phalodi, and Barmer — most houses traditionally had underground tanks called tankas? for storing drinking water. These could be remarkably large; one household in Phalodi had a tanka measuring 6.1 metres deep, 4.27 metres long, and 2.44 metres wide.
The tankas were part of a well-developed rooftop rainwater harvesting system. They were built inside the main house or courtyard and connected to the sloping rooftops through pipes. When rain fell, water flowed down the rooftops, through the pipes, and into the underground tank. The first spell of rain was typically not collected, as it served to wash the roofs and pipes clean. Subsequent rainfall was then stored.
The water stored in tankas could last until the next rainy season, making them an extremely reliable drinking water source during scorching summers when all other sources dried up. This rainwater, known locally as palar pani, was considered the purest form of natural water. Many houses even built underground rooms next to the tanka to stay cool during the summer heat.
Today, sadly, the practice of rooftop rainwater harvesting has declined in western Rajasthan, as the perennial Indira Gandhi Canal now provides plentiful water. However, some households still maintain their tankas, preferring the taste of rainwater to canal water.
Modern Adaptations of Rainwater Harvesting
Fortunately, rooftop rainwater harvesting is being successfully adapted across both rural and urban India. In Gendathur, a remote village in Mysuru, Karnataka, nearly 200 households have installed rooftop rainwater harvesting systems. With annual precipitation of about 1,000 mm and 80 per cent collection efficiency, each house collects approximately 50,000 litres annually. Together, the 200 houses harvest a net total of one crore (1,00,00,000) litres of rainwater each year.
Multi-Purpose Dams vs. Rainwater Harvesting — Comparison
L4 AnalyseRatings on a scale of 1–5 (5 = best). Rainwater harvesting scores higher on community control, environmental friendliness, and cost-effectiveness, while dams excel at large-scale electricity generation and flood control capacity.
Analyse: How does this folk song illustrate the need for flood control measures in river valleys? What does it tell us about the relationship between communities and rivers?
The textbook asks you to find out about rainwater harvesting systems existing in and around your locality.
- Does your school or any building in your area have a rainwater harvesting system?
- What traditional water conservation methods exist in your region?
- Has your state government made rainwater harvesting mandatory?
- What challenges do people face in implementing these systems?
The textbook asks you to prepare a list of inter-state water disputes in India.
- Identify at least three major inter-state water disputes in India.
- What are the main rivers involved in these disputes?
- Why do such disputes arise when dams or diversions are built upstream?
- How does the Inter-State Water Disputes Act help resolve these conflicts?
Competency-Based Questions
Reason (R): Sedimentation at the bottom of reservoirs reduces storage capacity and can cause overflow during excessive rainfall.
Reason (R): Tamil Nadu receives the lowest annual rainfall in India, making harvesting essential.
Reason (R): The Indira Gandhi Canal now provides a perennial water supply to the region, reducing dependence on traditional tankas.
Continue Learning — Chapter 3: Water Resources
Frequently Asked Questions
What are multi-purpose river projects?
Multi-purpose river projects are large dams built on rivers to serve multiple objectives including irrigation, hydroelectric power generation, flood control, water supply for industries and domestic use, navigation, and recreation. Examples include the Bhakra Nangal Dam (Sutlej River), Hirakud Dam (Mahanadi River), and Damodar Valley Project. Jawaharlal Nehru called them the temples of modern India. However, these projects have faced criticism for displacement of communities and environmental damage.
Why are large dams opposed in India?
Large dams in India are opposed for several reasons: they cause large-scale displacement of local communities, submerge vast areas of forest and agricultural land, alter natural river flow patterns, affect aquatic ecosystems, and lead to sedimentation reducing reservoir capacity. Movements like the Narmada Bachao Andolan led by Medha Patkar highlighted the social and environmental costs of the Sardar Sarovar Dam. Critics argue that multi-purpose projects often fail to achieve all their stated objectives simultaneously.
What is rainwater harvesting and what are its methods?
Rainwater harvesting is the technique of collecting and storing rainwater for later use. Methods include rooftop collection systems where rainwater from building roofs is channelled into storage tanks or underground wells, construction of check dams and percolation tanks, contour bunding on agricultural land, and traditional systems like tankas (underground tanks in Rajasthan), johads (earthen dams in Haryana), and surangams (horizontal wells in Kerala). Modern adaptations include recharge pits that direct rainwater into aquifers.
What are tankas in Rajasthan?
Tankas are underground tanks or cisterns used for storing rainwater in the arid regions of Rajasthan, particularly in the Thar Desert area of Bikaner, Barmer, and Jaisalmer. These cylindrical structures are built with lime plaster to prevent seepage and can store rainwater collected during the brief monsoon season for year-round use. Tankas were an integral part of every household in the region and are considered one of the most efficient traditional water harvesting systems in India. Many are now being revived as modern water scarcity increases.
What is bamboo drip irrigation?
Bamboo drip irrigation is a traditional water harvesting and irrigation technique practiced by the tribal communities of Meghalaya in northeast India. It uses bamboo pipes of different diameters to channel water from hill streams to agricultural terraces. The system delivers water drop by drop directly to the roots of plants, reducing wastage. This 200-year-old method is remarkably similar to modern drip irrigation technology and demonstrates the ingenuity of indigenous water management practices in India.
What is the Narmada Bachao Andolan?
The Narmada Bachao Andolan (Save the Narmada Movement) is a social movement led by Medha Patkar that has been opposing the Sardar Sarovar Dam and other large dam projects on the Narmada River since the late 1980s. The movement highlights the displacement of hundreds of thousands of tribal and rural people, submergence of agricultural land and forests, and inadequate rehabilitation. It has raised important questions about the cost-benefit analysis of large dam projects and the rights of affected communities in development decision-making.