Chapter 3 Water Resources

Water Scarcity And The Need For Water Conservation And Management

Water is a renewable resource, yet water scarcity is a growing problem globally and in India. Scarcity arises not just from low rainfall but primarily due to over-exploitation, excessive use, and unequal access to water. This affects agriculture, industry, and human survival, leading to health hazards, food insecurity, and ecological crises.

What Is Water Scarcity?

Water scarcity occurs when the demand for water exceeds the available supply, or when access to water is limited due to pollution or poor distribution. Areas with low rainfall and drought are prone to scarcity, but even regions with abundant rainfall can face it due to over-exploitation and pollution.

Causes Of Water Scarcity

• Over-exploitation and Excessive Use: Increasing population, industrialization, urbanization, and the expansion of irrigated agriculture (especially water-intensive crops) lead to overuse of freshwater resources, particularly groundwater.
• Pollution: Domestic sewage, industrial effluents, chemical pesticides, and fertilizers contaminate rivers and water bodies, making water unsafe for human use and reducing the availability of clean water.
• Unequal Access: Disparities in water distribution and access exist among different social groups and regions, with marginalized communities often facing greater scarcity.

Need For Water Conservation

Conserving and managing water resources is vital for ensuring food security, livelihoods, public health, and environmental sustainability. Over-exploitation and mismanagement can lead to resource depletion and ecological crises.

Multi- Purpose River Projects And Integrated Water Resources Management

Historically, sophisticated hydraulic structures like dams, reservoirs, and canals have been used for water management. Modern multi-purpose river projects, initiated after India's independence, aim to integrate various water uses like irrigation, power generation, flood control, domestic supply, and industrial needs.

What Are Dams?

Dams are barriers built across rivers to impound water, creating reservoirs. They are classified by structure (timber, earth, masonry) and height. Their purposes can be integrated into multi-purpose projects.

Hydraulic Structures In Ancient India

Ancient India had advanced water harvesting systems, including dams, lakes, embankments, and canals, demonstrating a long tradition of water management.

Purposes And Benefits Of Dams

Dams provide irrigation, hydroelectric power, water for domestic and industrial use, flood control, recreation, inland navigation, and support fisheries.

Opposition To Dams And Their Impacts

Multi-purpose projects face criticism due to significant environmental and social impacts, including submergence of forests and fertile land, displacement of communities (like tribals in the Narmada Bachao Andolan), disruption of river flow and sediment transport, damage to aquatic ecosystems, and increased salinity or alkalinity in soils due to water-intensive agriculture. They can also induce earthquakes and create water-borne diseases.

Conflicts Over Dams

Disputes often arise over the sharing of costs and benefits of multi-purpose projects among states (e.g., Krishna-Godavari dispute). Local communities displaced by projects often question whether they truly benefit, leading to protests against projects seen as prioritizing industrial or urban interests over local livelihoods.

Rainwater Harvesting

Rainwater harvesting is presented as a viable alternative to large dams, being socio-economically and environmentally sustainable. Traditional methods are discussed, along with modern adaptations.

Traditional Rainwater Harvesting Systems

These systems were adapted to local needs and conditions. Examples include 'guls' and 'kuls' in the Western Himalayas for irrigation, 'khadins' and 'Johads' in Rajasthan for storing water in semi-arid regions, and inundation channels in Bengal's floodplains.

Rooftop Rainwater Harvesting In Rajasthan (Tankas)

In Rajasthan's arid areas, 'tankas' (underground tanks) connected to rooftops were used to collect and store rainwater, providing a reliable drinking water source during dry periods.

Modern Rainwater Harvesting Techniques

Modern adaptations include rooftop rainwater harvesting systems in households (common in Gendathur, Karnataka) and the use of PVC pipes and filters. Tamil Nadu has mandated rooftop rainwater harvesting structures to combat water scarcity.

Bamboo Drip Irrigation System

A 200-year-old indigenous system in Meghalaya uses bamboo pipes to divert stream and spring water to agricultural fields, efficiently delivering water drop by drop to the plant roots.

Exercises

The exercises focus on understanding water scarcity, its causes, the benefits and drawbacks of multi-purpose river projects, and the methods of rainwater harvesting. Questions require identifying soil types related to water use, explaining the rationale behind dams, comparing traditional and modern harvesting techniques, and discussing the need for water conservation. Activities encourage students to propose water conservation methods, understand inter-state water disputes, and research local water management practices.