Water Resources (Advanced)

Water Scarcity And The Need For Water Conservation And Management

Water is essential for life, but its availability is unevenly distributed, and increasing demand coupled with pollution and climate change is leading to growing water scarcity worldwide. Addressing this requires effective conservation and management strategies.

What Is Water Scarcity?

Water scarcity occurs when the demand for water exceeds the available supply, or when poor quality restricts its use. It can be experienced in two main ways:

• Physical Water Scarcity: This occurs in regions that are naturally arid or semi-arid, or where water resources are being over-exploited. There simply isn't enough water to meet all demands, leading to competition among users.
• Economic Water Scarcity: This occurs when there are adequate water resources physically available, but lack of investment in infrastructure (like dams, pipelines, treatment plants) and human capacity prevents people from accessing safe and sufficient water. Many developing countries face economic water scarcity.

Water scarcity affects drinking water, sanitation, agriculture, industry, and ecosystems.

Causes Of Water Scarcity

Several interconnected factors contribute to water scarcity:

• Uneven Distribution: Rainfall is not uniform across the globe or even within regions, leading to localized shortages.
• Over-exploitation of Groundwater: Excessive pumping of groundwater for irrigation, industry, and domestic use lowers water tables, making it difficult to access water and can lead to land subsidence and saltwater intrusion in coastal areas.
• Pollution of Water Resources: Industrial effluents, untreated sewage, agricultural runoff (pesticides, fertilizers), and solid waste contaminate rivers, lakes, and groundwater, rendering them unusable.
• Increased Demand: A growing global population, expansion of agriculture (especially for irrigation), and industrialization all increase the demand for water.
• Climate Change: Changes in rainfall patterns, increased evaporation due to higher temperatures, melting glaciers, and more frequent extreme weather events (droughts, floods) exacerbate water scarcity.
• Inefficient Use: Wasteful practices in agriculture, industry, and households contribute to higher demand and reduced availability.

Need For Water Conservation

Water conservation is the practice of using water efficiently and minimizing wastage to ensure its availability for present and future generations. The need for water conservation is critical due to:

• Preserving Finite Resources: While water is renewable, freshwater sources are limited and unevenly distributed. Over-exploitation can deplete these sources.
• Protecting Ecosystems: Maintaining adequate water flows in rivers and lakes is crucial for aquatic life and healthy ecosystems.
• Ensuring Future Availability: Conserving water today ensures that it will be available for future generations, preventing potential conflicts and hardships.
• Reducing Energy Consumption: A significant amount of energy is used to pump, treat, and heat water. Conserving water also saves energy.
• Mitigating Climate Change Impacts: Water management and conservation are key to adapting to and mitigating the effects of climate change.
• Economic Benefits: Reducing water use can lower utility bills for households and reduce operational costs for industries.

Effective water management involves a combination of policy, technology, and behavioural changes.

Multi- Purpose River Projects And Integrated Water Resources Management

Multi-purpose river projects are large-scale engineering schemes designed to manage river water for a variety of beneficial uses, while Integrated Water Resources Management (IWRM) is a holistic approach to water management that aims to coordinate land and water resource development.

What Are Dams?

A dam is a barrier constructed across a flowing river or stream to hold back water. This stored water can then be released in a controlled manner for various purposes. Dams are a key component of multi-purpose river projects.

Hydraulic Structures In Ancient India

India has a long and rich history of developing hydraulic structures, demonstrating advanced engineering skills even in ancient times:

• Terrace Farming: Building terraces on slopes to conserve water and prevent soil erosion.
• Ring Wells, Tankas, and Embankments: Early forms of water storage and management, particularly in arid regions like Rajasthan.
• Dams and Lakes: Historical evidence suggests construction of dams and lakes for irrigation and water supply. For example, the step wells in Gujarat, like the famous Adalaj step well, served as water reservoirs and community gathering spaces.
• Canals: Elaborate canal systems were built for irrigation in various parts of the country during different empires.

These traditional systems were often integrated with the local environment and community needs.

Purposes And Benefits Of Dams

Multi-purpose river projects, often centered around dams, serve multiple objectives simultaneously, providing numerous benefits:

• Irrigation: Stored water is released through canals to irrigate agricultural fields, increasing crop yields and ensuring food security, especially in regions with erratic rainfall.
• Hydro-power Generation: The force of falling water from dams is used to drive turbines and generate electricity, a clean and renewable energy source.
• Flood Control: Dams can regulate the flow of rivers, storing excess water during floods and releasing it gradually, thereby preventing downstream damage.
• Water Supply: They provide water for domestic consumption, industrial use, and for cities.
• Navigation: Reservoirs created by dams can improve navigability of rivers, facilitating water transport.
• Fisheries: Reservoirs can support fish breeding, creating opportunities for fisheries.
• Recreation: Large reservoirs often create opportunities for tourism and recreational activities.

Examples of Multi-purpose Projects in India:

• Bhakra Nangal Project: On the Sutlej River, for power generation, irrigation, and flood control.
• Hirakud Project: On the Mahanadi River in Odisha, for irrigation, power generation, and flood control.
• Damodar Valley Project: On the Damodar River, for power generation, irrigation, and flood control.
• Kosi Project: On the Kosi River, for flood control and power generation.

Opposition To Dams And Their Impacts

Despite their benefits, multi-purpose river projects often face opposition due to their significant negative impacts:

• Environmental Impacts:
  • Submergence of Land: Large areas of fertile land, including forests and agricultural land, are often submerged under reservoirs, leading to loss of biodiversity and habitat.
  • Impact on Aquatic Ecosystems: Dams alter river flow, sediment transport, and water temperature, affecting fish migration and aquatic life.
  • Deforestation: Construction activities and submergence lead to significant deforestation.
  • Seismic Concerns: The immense weight of water in large reservoirs has been linked to induced seismicity (earthquakes) in some regions.
• Social Impacts:
  • Displacement of People: Large-scale projects often require the displacement of thousands of people, particularly tribal communities, from their homes and lands, leading to social disruption and loss of livelihood.
  • Loss of Livelihood: Communities dependent on riverine resources may lose their traditional livelihoods.
• Economic Impacts:
  • High Construction Costs: These projects are immensely expensive, with long gestation periods.
  • Siltation of Reservoirs: Over time, reservoirs can get filled with silt, reducing their storage capacity and the lifespan of the dam.

Notable examples of opposition include the Narmada Bachao Andolan against the Sardar Sarovar Dam.

Conflicts Over Dams

Conflicts over dams often arise due to:

• Inter-State Disputes: When dams are built on rivers flowing through multiple states, conflicts emerge over the sharing of water resources and the benefits derived from the project. For example, the Krishna River water disputes among Karnataka, Andhra Pradesh, and Maharashtra, or the Cauvery water dispute between Karnataka and Tamil Nadu.
• International Disputes: Dams built on international rivers can lead to disputes between countries regarding water sharing and downstream impacts. For example, the Indus River dispute between India and Pakistan, or the Mekong River issues involving China and Southeast Asian countries.
• Dam Affected People vs. Government/Developers: Conflicts arise from the displacement of communities, inadequate compensation, and environmental concerns, leading to protests and activism.

Integrated Water Resources Management (IWRM) aims to address these conflicts by promoting coordinated management of water, land, and related resources to maximize economic and social welfare in an equitable manner without compromising the sustainability of vital ecosystems.

Rainwater Harvesting

Rainwater harvesting is the process of collecting and storing rainwater for various uses, such as irrigation, domestic supply, and groundwater recharge. It is an age-old practice that has regained importance as a sustainable method to combat water scarcity and reduce dependence on conventional water sources.

Traditional Rainwater Harvesting Systems

India has a rich tradition of rainwater harvesting, with diverse methods adapted to different climatic and geographical conditions:

• Inundation Channels: Diversion of floodwaters onto land for irrigation.
• Rivulets and Streams: Channels were built to divert water for irrigation.
• Floodwater Farming: Utilizing floodwaters for cultivation in river plains.
• Sub-branch Channels: Irrigation channels dug from canals for wider water distribution.
• Talabs: Various types of ponds and lakes constructed to collect rainwater, often for drinking water and irrigation.
• Ollas: Small earthen dams constructed across streams for irrigation.
• Khadins: A specific type of structure in Rajasthan, built across the slopes of hills, consisting of a long earthen embankment constructed across the stream to capture monsoon runoff.

Rooftop Rainwater Harvesting In Rajasthan (Tankas)

Tankas are traditional underground storage tanks built in Rajasthan, particularly in arid regions, to collect rainwater. They are a remarkable example of ingenious water management in a water-scarce environment.

• Construction: Typically built by digging a pit and lining it with water-resistant materials like lime or cement. They are often located in courtyards or under the floor of houses.
• Collection: Rainwater from rooftops is channelled through pipes directly into the tankas, ensuring that the collected water is relatively clean.
• Purpose: Primarily used for drinking water, especially during the dry season when other water sources are unavailable.
• Significance: Tankas are a vital source of drinking water for many households, reducing the burden on women and children who traditionally walked long distances to fetch water.

Modern Rainwater Harvesting Techniques

Modern techniques adapt traditional principles for contemporary urban and rural settings:

• Rooftop Rainwater Harvesting: Collecting rainwater from rooftops of buildings (houses, schools, factories) and directing it to storage tanks or recharging groundwater through percolation pits or wells. This is increasingly being mandated in urban planning.
• Surface Runoff Harvesting: Collecting surface runoff from paved areas, playgrounds, and roads through channels and directing it to storage tanks or recharge structures.
• Groundwater Recharging: Techniques like percolation pits, trenches, recharge wells, and recharge galleries are used to replenish groundwater aquifers.

Bamboo Drip Irrigation System

The bamboo drip irrigation system is an ingenious and eco-friendly method of water conservation, particularly effective in hilly areas of Meghalaya, India. It uses bamboo pipes to transport water from natural springs to plantations, delivering it drop by drop to the roots of plants.

• Mechanism: Bamboo is carved into channels, and a network of pipes is created to divert water, often over several kilometres. The flow is regulated using a wooden plug or pebbles.
• Benefits:
• Water Efficiency: Delivers water directly to the plant roots, minimizing evaporation and wastage.
• Eco-friendly: Uses natural materials (bamboo) and requires no electricity.
• Cost-effective: Relatively inexpensive to set up and maintain.
• Sustainable: Promotes a sustainable approach to agriculture in challenging terrains.
• Application: Primarily used for irrigating areca nut and betel leaf plantations, but can be adapted for other crops.