Exhaustive Study Notes on Water Resources, Scarcity, and Conservation Management

Global Water Availability and the Phenomenon of Water Scarcity

• Global Surface Coverage and Freshwater Distribution:

  • Approximately $\frac{3}{4}$ of the Earth's surface is covered with water.

  • Only a very small proportion of this total water volume accounts for freshwater that can be put to human use.

  • Freshwater is primarily obtained from surface runoff and groundwater.

  • Freshwater is continually renewed and recharged through the hydrological cycle, which ensures that water remains a renewable resource.

• Projections on Global Water Scarcity:

  • Despite the abundance and renewability of water, severe regional shortages exist globally.

  • It is predicted that by the year $2025$, nearly $2\text{ billion}$ people worldwide will live in absolute water scarcity.

• Spatiotemporal Variations vs. Human-Induced Scarcity:

  • The availability of water resources varies significantly over space and time, primarily driven by seasonal and annual variations in precipitation.

  • Shortages are visually and intuitively associated with low rainfall or drought-prone regions, such as the deserts of Rajasthan where women travel long distances balancing multiple earthen pots (matkas) to collect drinking water.

  • In most cases, however, water scarcity is caused by over-exploitation, excessive use, and unequal access to water resources among different social groups.

Quantitative and Qualitative Causes of Water Scarcity

• Quantitative Drivers of Scarcity:

  • Population Growth: A large and expanding population increases domestic demand for water and necessitates higher food production.

  • Agricultural Over-Exploitation: To facilitate higher food-grain production, water resources are over-exploited to expand irrigated areas for dry-season agriculture. Irrigated agriculture is the single largest consumer of water.

  • Private Tube-Wells and Aquifer Depletion: Farmers frequently install personal wells and tube-wells on their land to increase farm yields. This widespread private extraction causes falling groundwater tables, severely threatening long-term water availability and national food security.

  • Post-Independence Industrialization: Rapid industrial expansion post-independence led to widespread establishment of large industrial units and Multinational Corporations (MNCs). Industries exert heavy pressure on freshwater resources both directly as heavy consumers and indirectly through high energy consumption (much of which is powered by hydroelectricity).

  • Urbanization and Urban Lifestyles: Dense urban centers and modern urban lifestyles elevate both water and energy requirements. Housing societies and urban colonies routinely employ private groundwater pumping devices, leading to severe depletion of fragile urban aquifers.

• Qualitative Drivers of Scarcity:

  • Water scarcity can occur even in regions with ample water supply if the available water is of bad quality.

  • Widespread water pollution is caused by domestic and industrial wastes, toxic chemicals, pesticides, and agricultural fertilizers, rendering the water hazardous for human consumption.

• Real-World Illustrative Incidents:

  • Kolkata Flood Crisis: Urban life was paralyzed following overnight record rainfall of $180 \text{mm}$, flooding vast areas and disrupting traffic, while residents were forced to collect drinking water from emergency sources amidst the floodwaters.

  • Kashmir Earthquake Relief: Disaster survivors in devastated Kashmiri villages carried drinking water across heavy snow covered terrain.

Government Policy Initiatives for Water Management

• Jal Jeevan Mission (JJM):

  • Priority and Objective: Accorded the highest priority by the Government of India to enhance the quality of life and ease of living in rural areas.

  • Target Level: Aims to enable every rural household to receive an assured supply of potable piped water at a service level of $55 \text{litres}$ per capita per day on a regular, long-term basis through functional tap water connections.

  • Policy Reference: Published in the Economic Survey 2020–21 (p. 357).

• Atal Bhujal Yojana (Atal Jal):

  • Scope and Coverage: Implemented across $8,220$ water-stressed Gram Panchayats in $229$ administrative blocks/talukas across $80$ districts in $7$ Indian states: Gujarat, Haryana, Karnataka, Madhya Pradesh, Maharashtra, Rajasthan, and Uttar Pradesh.

  • Target Area Burden: These $7$ states account for approximately $37 \text{\%}$ of the total water-stressed (over-exploited, critical, and semi-critical) blocks in India.

  • Primary Objective: Focuses on bringing behavioral changes in local communities, shifting attitudes from pure consumption to conservation and smart water management.

  • Policy Reference: Published in the Annual Report, Ministry of Jal Shakti, Government of India 2022–23.

• Pradhan Mantri Krishi Sinchayee Yojana (PMKSY):

  • Core Goal: Ensures access to protective irrigation for all agricultural farms in the country (har khet ko pani).

  • Key Objectives: Expands cultivable area under assured irrigation, enhances physical water access on farms, improves on-farm water use efficiency to reduce wastage (per drop more crop), and introduces sustainable conservation practices.

Historical Hydraulic Structures in Ancient India

• First Century B.C. (Sringaverapura): Built a sophisticated water harvesting system near Allahabad that channeled the floodwaters of the River Ganga.

• Mauryan Period: Extensive construction of dams, lakes, and irrigation systems occurred during the reign of Chandragupta Maurya.

• Regional Archaeological Evidence: Evidence of advanced ancient irrigation networks has been documented in:

  • Kalinga (Odisha)

  • Nagarjunakonda (Andhra Pradesh)

  • Bennur (Karnataka)

  • Kolhapur (Maharashtra)

• Eleventh Century (Bhopal Lake): Construction of Bhopal Lake, recognized as one of the largest artificial lakes of its era.

• Thirteenth–Fourteenth Century (Hauz Khas Tank): Constructed by Allauddin Khilji (Khalji) in Delhi to supply water to the Siri Fort area.

• Source Reference: Documented in Dying Wisdom, CSE, 1997.

Multi-Purpose River Projects and Dams

• Definition and Structural Mechanics:

  • A dam is a barrier built across flowing water that obstructs, directs, or retards flow, frequently creating a reservoir, lake, or impoundment.

  • The term "dam" technically refers to the impounded reservoir rather than the physical structure itself.

  • Dams feature a spillway or weir through which water flows continuously or intermittently.

• Classifications of Dams:

  • By Structure and Material: Timber dams, embankment dams, and masonry dams (with several sub-types).

  • By Height: Categorized as large dams and major dams, or alternatively as low dams, medium-height dams, and high dams.

• Functional Evolution:

  • Traditional Role: Built primarily to impound river water and rainwater for subsequent agricultural field irrigation.

  • Modern Role (Multi-Purpose Projects): Integrates multiple water management objectives, including electricity generation, domestic and industrial supply, flood control, recreation, inland navigation, and fish breeding.

• Key Examples of Integrated Basins:

  • Satluj-Beas River Basin: The Bhakra–Nangal project water is utilized for hydel power production and irrigation.

  • Mahanadi River Basin: The Hirakud project integrates water conservation directly with flood control.

• Socio-Economic Significance:

  • Post-independence multi-purpose projects were designed as vehicles for modern progress, overcoming the economic handicaps of the colonial past.

  • Jawaharlal Nehru proclaimed dams as the "temples of modern India," as they integrated agricultural and rural economic development with rapid industrialization and urban expansion.

• Cultural Context (Bhadu Folk Song):

  • Traditional Bhadu songs in the Damodar valley chronicle the distress caused by seasonal floods of the Damodar River (historically known as the "river of sorrow"). The song details agricultural cycles in the months of Asar and Bhadra, appealing for reduced flood intensity so sailing vessels can navigate.

Ecological, Environmental, and Social Impacts of Large Dams

• Upstream and Aquatic Disruptions:

  • Damming and regulating river flow disrupts natural flow regimes, leading to poor sediment transport and heavy sedimentation at reservoir bottoms.

  • Reservoir sedimentation results in rockier stream beds, creating degraded habitats for aquatic life.

  • Dams fragment river bodies, blocking the migration pathways of aquatic fauna, particularly for spawning.

  • Reservoirs created on floodplains submerge existing soil and vegetation, leading to gradual organic decomposition.

• Failure of Flood Control and Degradation:

  • Excessive reservoir sedimentation reduces storage capacity, causing dams to trigger or exacerbate severe flooding during periods of heavy rainfall.

  • Trapping sediment deprives downstream floodplains of natural silt (a natural fertilizer), accelerating land degradation.

  • Uncontrolled releases cause widespread life and property destruction alongside severe soil erosion.

• Seismic, Health, and Agricultural Consequences:

  • Large multi-purpose projects have been shown to induce seismic activity (earthquakes).

  • Water impoundments spread water-borne diseases, increase pest vectors, and cause chemical pollution from excessive water application.

  • Irrigation changes regional cropping patterns, encouraging shifts toward water-intensive commercial crops and causing severe soil salinisation.

Inter-State Water Disputes and Specific Project Profiles

• Krishna-Godavari Inter-State Dispute:

  • Dispute initiated due to objections raised by the state governments of Karnataka and Andhra Pradesh against the Maharashtra state government.

  • The dispute concerns Maharashtra's diversion of higher water volumes at Koyna for a multi-purpose power project.

  • This diversion reduces downstream river flow into Karnataka and Andhra Pradesh, adversely impacting regional agriculture and industrial output.

• Sardar Sarovar Dam Profile:

  • Location: Built across the Narmada River in Gujarat.

  • Multi-State Scope: One of India's largest water projects, covering $4$ states: Maharashtra, Madhya Pradesh, Gujarat, and Rajasthan.

  • Gujarat Command Area: Designed to irrigate $18.45\text{ lakh hectares}$ of land across $3,112$ villages in $15$ districts ($75 \text{\%}$ of the command area in Gujarat is drought-prone).

  • Rajasthan Command Area: Provides irrigation to $2,46,000\text{ hectares}$ in the desert districts of Barmer and Jalore (where $100 \text{\%}$ of the command area is drought-prone).

  • Maharashtra Command Area: Delivers lift irrigation to $37,500\text{ hectares}$ in tribal hilly tracts.

  • Source Reference: Sardar Sarovar Narmada Nigam Ltd.

• Geographic Distribution of Major Rivers and Dams in India:

  • Northern Basin: Indus River, Chenab River (Salal Project), Jhelum River, Ravi River, Satluj River (Bhakra Nangal), Yamuna River, Ganga River (Tehri Dam, Narora), Sarda River, Ghaghara River, Gandak River, Kosi River.

  • Central/Eastern Basin: Chambal River (Kota Barrage, Rana Pratap Sagar, Gandhi Sagar), Betwa River, Son River (Rihand Dam), Narmada River (Sardar Sarovar), Tapi River, Damodar River basin (Tilaiya, Maithon, Konar, Panchet), Mahanadi River (Hirakud Dam).

  • Southern Basin: Penganga River, Godavari River, Pravara River, Krishna River (Koyna Dam, Nagarjuna Sagar), Tungabhadra River (Tungabhadra Dam), Kaveri River (Mettur Dam), Ponnaiyar River, Periyar River.

Traditional Rainwater Harvesting Techniques Across India

• Mountainous and Hilly Regions:

  • In the Western Himalayas, communities constructed diversion channels known as guls or kuls to lead stream water to agricultural fields.

  • In Kaza village, a kul leads into a circular village tank from which water is systematically released when needed.

• Flood Plain Strategies:

  • In the flood plains of Bengal, communities developed specialized inundation channels to divert floodwaters into agricultural fields for crop irrigation.

• Arid and Semi-Arid Storage Systems (Rajasthan):

  • Agricultural fields were modified into rain-fed storage structures that impound runoff to moisten the soil, referred to as khadins in Jaisalmer and johads in other parts of Rajasthan.

  • In Bikaner, Phalodi, and Barmer, drinking water was stored in underground tanks called tankas built inside houses or courtyards.

• Underground Tanka Design and Operation:

  • Structure: Underground concrete/masonry tanks connected to sloping roofs via pipes. In Phalodi, one household tank measured $6.1 \text{metres}$ deep, $4.27\text{metres}$ long, and $2.44\text{metres}$ wide.

  • Operation: The initial spell of rain is allowed to run off to clean the roof and pipes; subsequent showers are funneled into the tanka.

  • Water Quality: Collected rainwater is locally termed palar pani and considered the purest form of natural water.

  • Thermal Control: Rooms were often constructed directly adjacent to or above underground tankas to beat summer heat and keep domestic living spaces cool.

Modern Adaptations and Case Studies in Rainwater Harvesting

• Standardized Rooftop Harvesting Mechanics:

  1. Rainwater from sloping rooftops is collected through standard PVC piping.

  2. Collected water is filtered using sand and brick filters.

  3. An underground pipe transfers filtered water directly to a sump for immediate consumption.

  4. Excess water from the sump is routed into a storage or recharge well.

  5. Water in the well recharges the underground aquifer (via hand pumps or abandoned dug wells) for later extraction.

• Declines and State Mandates:

  • Western Rajasthan: Traditional tanka use is declining due to continuous water supply from the perennial Indira Gandhi Canal, though select households retain tankas due to preference for rainwater taste over tap water.

  • Tamil Nadu Policy: First state in India to make rooftop rainwater harvesting compulsory for all houses statewide, backed by legal penalties for non-compliance.

• Shillong (Meghalaya) Case Study:

  • Shillong faces severe water scarcity despite being located only $55 \text{km}$ from Cherrapunjee and Mawsynram (which receive the highest rainfall in the world).

  • Rooftop rainwater harvesting is practiced across nearly every household in Shillong, fulfilling $15\text{--}25 \text{\%}$ of total domestic water needs.

• Gendathur Village (Karnataka) Case Study:

  • Located in Mysuru district, this remote village earned distinction as a rainwater-rich community after $200$ households installed rooftop harvesting systems.

  • Meteorological Data: Annual precipitation is $1,000 \text{mm}$.

  • Collection Metrics: Operating at $80 \text{\%}$ collection efficiency across $10$ fillings, each household collects and uses approximately $50,000\text{litres}$ of water annually.

  • Net Annual Harvest: Across all $200$ houses, the village collects a net total of $1,00,000 \text{litres}$ of rainwater annually.

Bamboo Drip Irrigation System of Meghalaya

• Historical Origin and Function:

  • A $200\text{-year-old}$ traditional system utilized in Meghalaya to tap perennial stream and spring water from hilltops using bamboo pipes.

• Water Transport Mechanics:

  • Approximately $18\text{--}20\text{litres}$ of spring water enters the primary bamboo inlet at hilltops.

  • Water is transported over hundreds of meters down steep slopes entirely via gravity flow.

Flow Regulation and Discharge:

• Through successive channel reductions and branched pipe layouts, water flow is throttled down to $20\text{--}80\text{drops per minute}$ at the final plant discharge site.

• Pipes crossing roads are elevated high above ground level on structural posts.

• Final channel sections drop water precisely adjacent to plant roots, with flow rates controlled by adjusting bamboo channel positions.