MEV 014: Unit 02 – Water Resources

 UNIT 2: WATER RESOURCES

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2.0 Introduction

Water is one of the most important natural resources essential for life. It supports agriculture, industries, domestic needs, and ecological systems. About 71% of the Earth’s surface is covered with water, but only 2.5% of it is freshwater suitable for human use—and even less is easily accessible.

In recent decades, water scarcity and pollution have emerged as major challenges due to rapid population growth, urbanization, industrialization, and climate change. Effective management and conservation of water resources are vital for sustainable development.

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2.1 Objectives

After studying this unit, you will be able to:

·         Understand the sources and distribution of water on Earth.

·         Differentiate between surface and groundwater.

·         Identify causes and consequences of over-utilization of water resources.

·         Analyze water-related conflicts.

·         Examine the environmental impacts of water exploitation.

·         Recognize the importance of conserving water resources.

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2.2 Water Resources

Water resources refer to all sources of freshwater that are used for various human and ecological purposes such as drinking, agriculture, sanitation, industry, and recreation.

2.2.1 Distribution and Supply of Water

Though water is abundant, freshwater is unevenly distributed across the globe and even within countries.

Global Water Distribution:

·         Oceans: 97.5% (saline)

·         Freshwater: 2.5%

o    Glaciers and ice caps: ~68.7%

o    Groundwater: ~30.1%

o    Surface water (lakes, rivers, swamps): ~1.2%

In India:

·         India receives around 4% of the world's freshwater, but houses about 18% of the global population.

·         Major water sources: rivers (Ganga, Brahmaputra, Godavari), lakes, groundwater aquifers, and rainfall.

The supply is influenced by climate, seasonal rainfall, topography, and human usage.

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2.2.2 Surface Water and Groundwater

Surface Water:

Surface water is found in rivers, lakes, ponds, and reservoirs. It is visible and replenished by rainfall and melting snow.

Uses:

·         Drinking water

·         Irrigation

·         Hydropower

·         Fishing and navigation

Challenges:

·         Pollution from domestic, agricultural, and industrial waste

·         Drying rivers due to overuse and climate change

Groundwater:

Groundwater is stored beneath the Earth's surface in aquifers. It is extracted through wells, hand pumps, and borewells.

Advantages:

·         Less polluted

·         Available year-round

·         Used in rural and urban water supply

Concerns:

·         Over-extraction leading to falling water tables

·         Arsenic and fluoride contamination

·         Drying up of wells and borewells

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2.2.3 Use and Over-utilization of Surface and Groundwater

Water is used for multiple purposes, but overuse has led to serious concerns.

Major Uses:

·         Agriculture: Largest consumer (70-80% of freshwater)

·         Domestic use: Drinking, cooking, sanitation

·         Industrial use: Cooling, processing, cleaning

·         Hydropower and recreation

Over-utilization Issues:

·         Depletion of water tables

·         Drying rivers and lakes

·         Reduced river flows and dying wetlands

·         Decline in water quality

·         Inefficient irrigation techniques (flood irrigation)

Case Example:

·         Punjab and Haryana: Excessive groundwater use for paddy farming has led to falling water tables and dependence on electric pumps.

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2.3 Conflicts Over Water

Water conflicts arise when different groups or regions compete for limited water resources.

Types of Conflicts:

·         Interstate conflicts: Example – Cauvery River dispute between Karnataka and Tamil Nadu.

·         International disputes: Example – Indus Water Treaty between India and Pakistan.

·         Urban vs Rural needs

·         Agricultural vs Industrial demand

·         Upstream vs Downstream users

Reasons for Conflict:

·         Uneven distribution of water

·         Seasonal variation in availability

·         Population growth and increased demand

·         Lack of proper management and sharing mechanisms

Resolution Strategies:

·         Water-sharing agreements

·         Mediation by government or courts

·         River basin management authorities

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2.4 Environmental Impact of Water Exploitation

Overexploitation and mismanagement of water resources can lead to serious environmental consequences.

Key Impacts:

1. Lowering of Groundwater Table:

Excessive pumping of groundwater causes aquifers to dry up and wells to fail.

2. Water Pollution:

Disposal of industrial, agricultural, and domestic waste pollutes rivers, lakes, and groundwater.

3. Loss of Biodiversity:

Aquatic species suffer due to pollution, dams, and alteration of natural water flows.

4. Soil Degradation and Waterlogging:

Over-irrigation causes salinization and loss of fertility, especially in canal-irrigated areas.

5. Damming of Rivers:

Though useful for power and irrigation, large dams displace people, submerge forests, and disturb ecosystems.

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2.5 Let Us Sum Up

·         Water is a vital but limited resource.

·         Freshwater is only a small portion of the total water available on Earth.

·         Surface water and groundwater serve multiple uses but are overused and polluted.

·         Water conflicts are increasing due to competing demands and poor management.

·         The environmental consequences of water misuse are severe and affect ecosystems, biodiversity, and future water security.

Conclusion:
We must adopt sustainable water use practices, improve water governance, and invest in water conservation technologies like rainwater harvesting and drip irrigation.