Key Concepts: Water Resources

Table of Contents
1. Earth's Water Composition
2. Sources and Cycle of Freshwater
3. Water Scarcity: Causes and Challenges
4. Government Initiatives
5. Traditional and Modern Water Management Systems
6. Water Conservation Techniques
7. Conclusion
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1. Earth's Water Composition

• 71% of the Earth's surface is covered by water.
• Of this water, 97% is saltwater (in oceans) and is not directly usable for drinking or most irrigation unless treated.
• Only about 3% is freshwater. Freshwater exists in forms such as glaciers and ice caps, groundwater, lakes, rivers and soil moisture; much of it is not readily accessible.

2. Sources and Cycle of Freshwater

The hydrological cycle (water cycle) is the continuous movement of water between the atmosphere, land and oceans through the processes of evaporation, transpiration, condensation, precipitation and runoff. This cycle renews freshwater and makes water a renewable resource, although local availability varies with climate, geology and human use.

Main components of the hydrological cycle

• Evaporation from oceans, lakes and soils.
• Transpiration from plants (often grouped with evaporation as evapotranspiration).
• Condensation to form clouds.
• Precipitation as rain, snow or hail.
• Surface runoff into rivers and lakes.
• Infiltration and groundwater recharge into aquifers.

Much of the Earth's freshwater is locked in glaciers and ice caps; a smaller proportion is stored as groundwater, lakes and rivers. The hydrological cycle governs the redistribution of this freshwater and determines when and where it becomes available for human use.

Hydrological Cycle

3. Water Scarcity: Causes and Challenges

Water scarcity occurs even where total water resources appear large because of unequal access, poor management and pollution. Water scarcity persists due to a combination of natural and human factors.

• Unequal distribution: Spatial and seasonal variations in rainfall create shortages in some regions while others receive plentiful rain.
• Overexploitation: Excessive withdrawal of groundwater and surface water for irrigation, industry and cities lowers water tables and reduces long-term supplies.
• Pollution: Contamination of surface and groundwater by industrial effluents, sewage, pesticides and fertilisers reduces the amount of safe water available.
• Rising demand: Population growth, urbanisation and industrialisation increase water needs for domestic, agricultural and manufacturing uses.

Key issues

• Overuse in agriculture, especially in regions practising extensive irrigated farming.
• High water demand from industries and urban areas, including for cooling, processing and domestic consumption.
• Pollution from domestic and industrial waste, pesticides and fertilisers that degrade water quality.
• Quality issues make even available water unsafe for consumption without treatment, increasing the burden on communities and public health systems.

4. Government Initiatives

Jal Jeevan Mission (JJM)

• Seeks to provide 55 litres/person/day of clean piped water to every rural household.
• Focuses on the quality and regular supply of water to reduce health hazards from polluted water.
• Places emphasis on decentralised water supply systems, community participation and local asset maintenance.

Pradhan Mantri Krishi Sinchayee Yojana (PMKSY)

• Aims to improve irrigation infrastructure across the country.
• Promotes water-use efficiency with the slogan "more crop per drop".
• Encourages sustainable farming and adoption of water-saving technologies such as micro-irrigation and efficient water management practices.

5. Traditional and Modern Water Management Systems

A. Ancient hydraulic structures

Historic water systems were constructed to harvest, store and distribute water for drinking, irrigation and local flood control. These include tanks, stepwells, canals, lakes and small dams developed by earlier civilisations.

• Dams, lakes and canals were built in the Mauryan and later Sultanate periods to manage water for agriculture and towns.
• Notable historical examples include the Bhopal Lake, the Hauz Khas tank in Delhi, and water management systems in regions of Kalinga and Kolhapur.

B. Dams as multi-purpose projects

Dams are constructed to provide irrigation, hydropower, water supply, flood control and recreation.

• Examples: Bhakra-Nangal (irrigation and hydroelectric power) and Hirakud (flood control and conservation).

Advantages of dams

• Provide regular water supply for irrigation and domestic use.
• Generation of hydroelectric power.
• Moderate floods and create reservoirs for long-term water storage.

Disadvantages of dams

• Sedimentation reduces reservoir capacity over time.
• Ecological impacts alter river ecology and aquatic life downstream.
• Displacement and social costs arise from resettlement of affected communities and sometimes inter-state disputes over water sharing.
• In extreme events, large dams may still be unable to fully control floods.

C. Cropping pattern shift

The expansion of irrigation has encouraged the cultivation of water-intensive commercial crops in many regions.

• This can lead to soil salinisation where poor drainage causes salts to accumulate in the root zone.
• It can increase social inequality between large landowners who can pay for irrigation and the landless or smallholders who cannot.
• Overall, it contributes to increased water stress and depletion of groundwater resources.

6. Water Conservation Techniques

A. Rainwater harvesting (RWH)

Rainwater harvesting involves collecting and storing rainwater from rooftops, paved surfaces or catchment areas for later use or for recharging groundwater.

• Rainwater is collected from rooftops or other surfaces through gutters and pipes.
• Collected water is stored in underground tanks, cisterns or percolation structures that recharge aquifers.
• RWH is effective in both urban and arid rural areas and reduces dependence on distant water sources.

Case studies

• Rajasthan: Use of underground tanks (tanka) and community harvesting to store scarce rainwater for drinking.
• Shillong: Despite high regional rainfall, local shortages are tackled using rooftop rainwater harvesting and storage systems.
• Gendathur (Karnataka): Community-level harvesting projects collect around 1,00,000 litres annually for local needs.
• Tamil Nadu: Was the first state to make rainwater harvesting legally mandatory in all homes to conserve water and recharge groundwater.

B. Bamboo drip irrigation (Meghalaya)

• Traditional system that uses bamboo pipes to channel spring water to crops.
• Water-saving and eco-friendly, supplying precise droplets of water directly to plant roots and reducing wastage.
• Suitable for hilly and small-holder farming systems where low-cost, locally available materials are preferred.

Conclusion

Although the Earth appears abundant in water, freshwater availability is limited and threatened by human activities such as overuse, pollution and unsustainable cropping patterns. Sustainable management requires coordinated action:

• Government initiatives that provide safe, regular supplies and invest in efficient infrastructure.
• Technological solutions such as micro-irrigation, water treatment and monitoring to increase water-use efficiency.
• Traditional practices like rainwater harvesting and locally adapted methods (for example, bamboo drip irrigation) that conserve water and recharge groundwater.

Combining policy, technology and community-based traditional practices is essential to ensure equitable and long-term access to water for all.