Environment and Sustainability Unit 2 – AKTU B.Tech 1st Year

Course: Environment & Sustainability

University: AKTU

Programme: B.Tech First Year | Semester I & II

Course Codes: AAC101 / AAC201

Unit: II – Natural Resources and Their Conservation

Common Streams: CSE, EE, ECE, CE, ME, BT, CH, TX & AG

Website: www.notesgallery.com

Unit II Introduction

Natural Resources and their Conservation connects the water we use, the materials we buy, the land that supports food production and the energy that runs daily life. It explains why resource use must be considered together with renewal, environmental quality and the needs of other users.

The unit develops practical ways to conserve resources without losing the services they provide. Examples include repairing leaks, protecting soil, extending product life and collecting suitable rooftop runoff. The emphasis is on understanding the reason behind an action, rather than memorising slogans.

These Environment and Sustainability Unit 2 Notes include the unit’s explanations, tables, examples, calculations, activities, model answers and examination questions.

Syllabus Coverage

Common syllabus: All nine listed streams. Calculations are constructed examples; illustrations are conceptual, not site-survey records.

Learning Outcomes

• Classify renewable and non-renewable resources with suitable examples.
• Explain water scarcity as a problem of quantity, quality, access and timing.
• Suggest practical water, forest, land and energy conservation measures.
• Explain how excessive extraction can damage resource stocks and renewal processes.
• Distinguish Reduce, Reuse and Recycle using everyday products.
• Draw and explain a rooftop rainwater-harvesting system.
• Use units correctly in simple water and electricity calculations.
• Plan a small campus observation and propose a measurable resource-saving action.

Key Vocabulary

Core Study Question

What service is needed, which resource supplies it, where is avoidable loss occurring, and how can the same need be met with less damage and waste?

Use this question throughout these Environment and Sustainability Unit 2 Notes.

1. Natural Resources

1.1 Meaning and Scope

A natural resource is a material, energy flow or useful feature of nature that supports life and human activities. Water, soil, forests, sunlight, wind, minerals and fossil fuels are familiar examples. Their value includes ecological functions as well as the products people directly collect or buy.

A river can supply water, support aquatic life and provide cultural value. A forest supplies timber and other products while providing habitat and influencing soil and water processes. Counting only the marketable product gives an incomplete picture of what may be lost through careless use.

Diagram classification

Regeneration and impacts still need attention.

1.2 Resource and Service

A resource is what is used; a service is the need it helps satisfy. Electricity powers lighting, but adequate illumination is the service. Water is used in cleaning, but cleanliness is the service. This distinction helps identify ways of meeting a need with less input.

Example

Using daylight where suitable can reduce electricity needed for lighting. It does not mean that the need for safe, comfortable illumination has disappeared.

1.3 Why Resources Need Management

Availability varies

Resources are not distributed evenly. A place may receive substantial seasonal rainfall yet lack dependable water in the dry months. A mineral deposit may exist but be difficult to extract. Useful availability depends on location, quality, timing, technology and access, not only on physical presence.

Use creates connected effects

Extracting, processing, transporting and disposing of a material can use land, water and energy. A product’s impact therefore begins before purchase and continues after disposal. Conservation examines the whole chain, while avoiding the assumption that every alternative has the same impact.

1.4 Conservation Is Purposeful Use

Conservation means protecting resources and managing their use so that ecological functions and future needs are considered. It does not require stopping all human use. It asks whether extraction is necessary, whether loss can be avoided and whether recovery processes and affected users are protected.

Short-answer practice

Question: Why is a forest more than a source of timber?

Answer: It is a living ecosystem that provides habitat, supports ecological interactions and helps protect soil and regulate water movement. Timber value alone does not represent these functions.

2. Renewable Resources

2.1 Basic Meaning

A renewable resource is replenished by natural processes over a timescale relevant to use. Solar radiation and wind are continuing flows. Forest biomass and freshwater stores are renewed through biological growth and the water cycle, but their usable stocks depend on conditions and management.

2.2 Renewal Is Not Unlimited Supply

A forest may regenerate, yet harvesting faster than regrowth reduces its standing biomass. Water is renewed through the hydrological cycle, yet pumping can lower a local aquifer when withdrawals exceed net replenishment. Renewable therefore does not mean that any amount can be used anywhere at any time.

2.3 Conditional Renewability

Living resources need the conditions that allow regeneration. Seeds, breeding populations, suitable habitat, water and soil may all matter. Removing the productive base can turn a recoverable loss into persistent degradation. The relevant question is not just “Can it regrow?” but “Can it recover under the actual conditions?”

Memory cue

Renewable describes replenishment; sustainable describes how use is managed. They are related ideas, but they are not interchangeable words.

2.4 Non-Renewable Resources

A non-renewable resource is not replenished fast enough to replace human use on ordinary planning timescales. Coal, petroleum and natural gas formed through geological processes. Mineral ores are also finite deposits, although many metals can be recovered and used again.

Fuels and minerals differ

Burning a fossil fuel transforms its chemical energy and material composition; the original fuel cannot simply be reused. A metal object may retain recoverable material after use. Recycling reduces demand for newly mined ore, but collection losses, contamination and processing requirements prevent perfect recovery.

2.5 Common Classification Errors

Electricity is an energy carrier, not automatically a renewable resource. Its source may be coal, solar, wind, hydro or another technology. Soil is also not “quickly renewable” simply because it is natural: soil formation can be slow, and erosion can remove productive topsoil much faster than it develops.

Check your reasoning

Question: Does recycling aluminium make bauxite a renewable resource?

Answer: No. Bauxite remains a finite mineral resource. Recycling keeps aluminium in use and can reduce the need for further extraction; it does not regenerate the original ore deposit.

3. Stocks, Flows and Conservation

3.1 Stock and Flow

A stock is an amount present at a particular time, such as water stored in a tank or the standing biomass of a forest. A flow is an amount moving per unit time, such as litres used per day or tonnes harvested per year. Comparing a stock directly with a flow without a time period is incorrect.

Diagram labels and explanation

• Resource stock: Amount available now.
• Additions: Renewal or recharge add to the stock.
• Withdrawals: Extraction or use remove from the stock.
• Other inflows and outflows may also matter.
• Persistent net withdrawal reduces the stock.

3.2 A Simple Balance

For a defined boundary and period:

Final stock = Initial stock + Additions − Withdrawals.

This is a bookkeeping relationship, not proof that a real resource has only two flows. Evaporation, leakage, natural discharge or other losses must be included when relevant.

Constructed tank example

A tank begins with 800 L, receives 600 L and supplies 900 L.

If there are no other flows:

Final storage = 800 + 600 − 900 = 500 L.

State the time period and assumptions.

3.3 Interdependent Resources

Water–land connection

Vegetation and soil conditions influence how rain becomes infiltration, storage and runoff. Erosion can carry sediment into streams and reservoirs. Protecting land in a catchment can therefore support water-resource management, although the result depends on rainfall, geology, slope and land use.

Water–energy connection

Water may require energy for pumping, treatment and distribution. Energy production can also require water, depending on the technology. Avoiding unnecessary water demand can therefore reduce associated energy use, but the saving must be evaluated for the actual system rather than assumed from a universal factor.

Materials–energy connection

Making a new product may require extraction, transport and processing. Keeping a serviceable product in use can avoid some replacement demand. However, the balance may differ for an inefficient appliance whose operating energy dominates its impact. Good decisions consider both production and use.

Complementary approaches

3.4 Equity and Future Needs

Resource conservation also concerns who receives benefits and who bears damage. Unchecked extraction may benefit some users while reducing access for others. Planning should consider essential needs, downstream effects and the ability of future users to meet their needs.

Exam distinction

Efficiency means less input for a useful output. Conservation is broader: it includes avoiding unnecessary demand and protecting the resource itself. A highly efficient device can still increase total use if it is used much more often.

4. Water Resources

4.1 Sources of Usable Water

Freshwater resources include surface water in rivers, lakes, ponds and reservoirs, groundwater in aquifers, and rainwater that can be collected where suitable. These sources are connected through the water cycle. A reservoir stores water; it does not create new rainfall or remove all seasonal variability.

Diagram labels

• Evaporation.
• Condensation.
• Rainfall.
• Runoff.
• Infiltration.
• Groundwater flow.

Selected water pathways are shown; arrows are qualitative.

4.2 Surface Water

Surface-water availability changes with rainfall, upstream flow, storage and withdrawals. Rivers and lakes also support ecosystems. Taking water for one purpose can affect other users and habitats, particularly during low-flow periods. Conservation must therefore consider both human demand and ecological requirements.

Useful distinction

Infiltration is water entering the ground surface. Recharge is water reaching and adding to groundwater storage. Not all infiltrated water becomes groundwater; some remains in soil or returns to the atmosphere.

4.3 Groundwater and Aquifers

Groundwater occurs below the water table in saturated pores or fractures. An aquifer is a geological formation that stores and transmits enough water to supply wells or springs. It is usually not an open underground lake; water occupies spaces in rock and sediment.

Recharge and discharge

Rainwater or surface water may move downward and recharge an aquifer where conditions allow. Groundwater may discharge naturally to springs, streams or wetlands, or be removed by pumping. Its storage changes when the combined inflows and outflows do not balance over the period considered.

4.4 Quantity and Quality

Water that is physically present is not always suitable for every purpose. Drinking, irrigation, washing and industrial processes have different quality requirements. Contamination can reduce usable supply and increase treatment needs. Conservation includes protecting water quality as well as reducing avoidable withdrawal.

Worked interpretation

Statement: “The town has a river, so water scarcity is impossible.”

Correction: A river may have low dry-season flow, poor quality, insufficient distribution or demand that exceeds dependable supply. Water presence alone does not demonstrate reliable access.

5. Water Scarcity

5.1 Meaning

Water scarcity occurs when dependable, suitable water is insufficient to meet needs in a place and period. It may result from limited physical supply, excessive demand, poor quality, inadequate infrastructure or unequal access. A complete explanation identifies the local combination of causes.

5.2 Natural and Seasonal Factors

Low rainfall, drought, high evaporative demand and uneven rainfall through the year can restrict availability. An intense rainy season may produce substantial runoff without providing dependable dry-season storage. Rainfall totals should therefore be interpreted together with timing, storage and local conditions.

5.3 Demand and Management Factors

Growing demand, water-intensive activities, leaking pipes, uncontrolled pumping and poorly maintained systems can intensify scarcity. Paving can alter infiltration and runoff. Pollution can make a source less usable. These drivers often act together rather than as isolated problems.

Drought versus scarcity

Drought is an unusually dry period relative to expected conditions. Scarcity is a shortage relative to needs and access. Scarcity can occur without drought, and good management can reduce vulnerability during a drought.

5.4 Effects of Water Scarcity

Households and institutions

Unreliable supply interrupts cleaning, sanitation and everyday activities. Extra pumping, storage and collection can increase cost and effort. Schools, hostels and laboratories may need to reschedule activities or arrange supplementary supply. The effects are often greater for users with fewer alternatives.

Farming and ecosystems

Water shortage can constrain crop growth and livestock care. Reduced river flow or altered groundwater discharge can affect aquatic and wetland habitats. A conservation plan should avoid treating all water that remains in the environment as unused or wasted.

5.5 A Cause-Based Response

A response should match the diagnosed problem. Repairing distribution losses helps when leakage is significant. Demand management reduces unnecessary use. Source protection supports usable quality. Harvesting rain may supplement supply, but its benefit depends on rainfall, catchment, storage and maintenance.

Campus case: morning shortage

A hostel reports low water pressure each morning. Possible explanations include peak demand, an undersized distribution line, pump scheduling, leakage or insufficient storage. The complaint alone does not identify the cause. Review supply times and meter records, inspect authorised areas and compare demand at different times before proposing a major new source.

How to write a balanced answer

Start with the meaning of scarcity. Group causes into supply, demand, quality and access. Explain two or three effects. Then connect each proposed measure to a cause. For example: “Repair overflowing tanks to reduce avoidable loss,” rather than simply listing “save water” as a solution.

Memory cue: four checks

Ask how much water, what quality, when available and who can access it. These checks explain why a region with rainfall can still experience shortages.

6. Water Conservation in Daily Life

6.1 Prevent Avoidable Losses

Repair leaking taps and pipes, prevent tank overflow and report faulty fixtures. These actions conserve water without reducing useful service. A recurring leak should be investigated at its cause; repeatedly collecting lost water without fixing the fault may leave the main loss unchanged.

6.2 Change the Method

Use a controlled quantity for cleaning rather than leaving a hose running unnecessarily. Turn off a tap during intervals when water is not needed. Operate appliances with suitable loads and settings. The best action depends on the activity and should still achieve adequate cleaning and hygiene.

6.3 Garden and Outdoor Use

Choose plants suited to the local climate and site. Mulch can reduce soil evaporation and protect the surface. Water close to the root zone and avoid unnecessary runoff. Irrigation scheduling should reflect soil moisture, plant need and weather; fixed daily watering is not always appropriate.

Reuse requires suitability

Reusing water is not automatically appropriate for every task. Its quality and the proposed use must be compatible. Keep non-potable supplies separate and clearly identified; follow the institution’s approved arrangements.

6.4 Simple Leak Calculation

Constructed example: A small leak loses 0.20 L each minute and continues all day. Find the loss over one day and over 30 days, assuming the rate remains constant.

Step 1: Convert one day to minutes.

24 × 60 = 1,440 min.

Step 2: Multiply flow by time.

0.20 L/min × 1,440 min = 288 L/day.

Step 3: Extend to 30 days.

288 × 30 = 8,640 L = 8.64 m³.

This is an estimated loss, not a guaranteed saving. If the leak stops after repair, the avoided loss is approximately this amount under the same operating conditions. If pressure or hours of supply change, the actual avoided volume may differ.

6.5 Measuring a Safe, Accessible Flow

With permission, a normal outlet can be timed while filling a container of known volume.

Flow rate = Volume ÷ Time.

Repeat the measurement and record conditions. Do not interfere with mains, pressurised equipment or restricted installations; facility staff should inspect those systems.

Prioritise the biggest justified saving

A visibly dripping tap attracts attention, but a concealed pipe leak or overflowing tank may lose more. Compare estimated volumes, ease of repair and reliability of evidence. Conservation improves when action is followed by checking whether the fault and the loss actually stopped.

Model conclusion

“Repair the measured leak, record the repair date and compare the estimated or metered loss afterwards.”

This is stronger than claiming an exact annual saving from a single observation with no follow-up.

When the supply is intermittent

If the example leak occurs only during an 8-hour supply period each day, use 480 minutes, not 1,440.

Loss = 0.20 × 480 = 96 L/day.

Thirty-day loss = 2,880 L.

Record the actual hours and whether the rate changes with pressure. Applying a continuous-supply estimate to an intermittent system would overstate the loss.

7. Groundwater Conservation

7.1 Why Water Levels Can Decline

When pumping and other outflows exceed replenishment over a sustained period, groundwater storage may fall. A deeper water level can increase pumping requirements and affect shallow wells. The response depends on aquifer properties, recharge, discharge and the distribution of pumping.

Diagram labels

• Pumping.
• Recharge.
• Earlier water table.
• Lower water table.
• Saturated pores below the water table.

The unconfined aquifer is simplified and not to scale.

7.2 Protect Recharge Conditions

Where appropriate, retain permeable ground, protect water bodies and maintain suitable infiltration areas. Avoid dumping waste or contaminated water where it could enter groundwater. Artificial recharge requires site assessment; a recharge pit is not a universal solution for every soil, aquifer or drainage condition.

Key distinction

A rainwater tank stores water for later use. A recharge structure aims to help suitable water enter the ground. They serve different purposes and require different checks.

7.3 Demand and Recharge Together

Reduce unnecessary pumping

Repair losses, choose efficient processes and schedule water use according to actual need. A new borewell may temporarily increase supply to one user while adding pressure to the same aquifer. Conservation should address total demand and the shared resource rather than only deepening the source.

Recharge has limits

Soil permeability, geology, available space, groundwater depth and source-water quality affect feasibility. Recharge must not become a route for pollution. Even a suitable structure cannot compensate for unlimited withdrawal or guarantee that all collected water reaches a particular well.

7.4 Interpreting Observations

One water-level reading does not establish a long-term trend. Levels may vary with season, recent pumping and nearby abstraction. A useful comparison uses consistent locations and methods, records the timing of pumping and rainfall, and draws on competent monitoring where available.

Exam question

Why is rainwater harvesting not enough by itself to solve groundwater depletion?

Because recharge is limited by rainfall and site conditions, while withdrawals and other outflows continue. Demand reduction, source protection and appropriate monitoring must accompany feasible recharge measures.

8. Forest Resources

8.1 A Forest as a Living System

Illustration labels

• Tree canopy.
• Wooded slopes.
• Stream bank.
• Leaf litter.
• Ground vegetation.
• Stream channel.

Products and livelihoods

Forests provide timber, fuelwood, fibres, foods and other biological products. Many communities depend on these resources for livelihoods and cultural practices. Management should consider regeneration, access and ecological condition alongside the quantity harvested.

Soil protection

Canopy, ground vegetation, roots and leaf litter affect how rainfall reaches the soil and how the surface resists erosion. Litter and organic matter support soil organisms. Removing cover and repeatedly disturbing the ground can weaken these functions.

Read the illustration

The stream bank, forest floor and wooded slopes are connected. Damage to an upslope area may influence the channel through sediment movement; the exact outcome depends on local conditions.

Habitat and biodiversity

A forest provides varied niches, food and shelter. Standing trees, understory plants, deadwood, soil organisms and water features contribute different functions. A uniform tree plantation may supply useful wood but does not automatically reproduce the biodiversity of a natural forest.

Water and climate connections

Forests influence infiltration, evapotranspiration and runoff, and store carbon in vegetation and soils. Their effects on water yield depend on climate, soils, species and land use. Avoid the simplistic claim that planting more trees always increases the amount of water in a river.

Core answer

Forest conservation protects structure, regeneration and useful products. Planting needs suitable species, locations and long-term care.

9. Forest Loss and Conservation

9.1 Pressures on Forests

Conversion to other land uses, excessive or damaging harvest, repeated disturbance and poorly managed fire can reduce forest cover or condition. A forest can be degraded even when some trees remain. Fragmentation may also isolate habitat patches and alter movement and ecological interactions.

9.2 Effects of Degradation

Loss of vegetation can expose soil, reduce habitat and change local water movement. Unsustainable removal of products can reduce future supply and affect livelihoods. The severity depends on the disturbance, landscape and ability of the system to regenerate.

9.3 Protect Existing Forest

Avoid unnecessary clearing, maintain suitable habitat connections and protect regeneration. The management method should match the forest type and local conditions. Restoring damaged land is valuable, but it is not a reason to treat the loss of an established, diverse forest as easily reversible.

Concept check

Forest cover, tree cover, timber stock and biodiversity are related but different measures. A rise in one does not automatically prove improvement in all the others.

9.4 Practical Conservation Measures

Regeneration and responsible use

Where harvesting is appropriate, protect future growth and avoid removal faster than recovery. Retain ecological features needed by wildlife and soil processes. Appropriate management also considers the needs and knowledge of local users and the distribution of benefits.

Afforestation and restoration

Afforestation establishes forest on land that is not presently forested; reforestation restores forest cover on previously forested land. Ecological restoration aims more broadly to recover a degraded ecosystem’s structure and functions. The most suitable action depends on the site, including whether it was naturally a grassland or wetland.

Choose appropriate planting

Use species and planting methods suited to the local ecosystem and available water. Protect saplings, allow space for growth and plan aftercare. Counting the number planted on one day says little about survival or ecological success after several seasons.

What students can do

• Reduce unnecessary paper use and use existing notebooks efficiently.
• Avoid damaging bark, roots, saplings and forest-floor habitat.
• Support approved planting or restoration with follow-up care.
• Check whether a campus green patch needs protection rather than clearing and replanting.

Model short answer

Why is a plantation not always an ecological substitute for a natural forest?

A plantation may have fewer species, a simpler age structure and different ground vegetation, deadwood and habitat connections. It can provide products, but these features may not replace the ecological relationships and diversity of the original forest.

10. Land and Soil Resources

10.1 Conservation in the Field

Illustration labels

• Field-edge trees.
• Terrace steps.
• Crop cover.
• Straw mulch.
• Earthen bund.
• Vegetated riser.

Land as a resource

Land supports agriculture, settlements, transport, industries and habitats. Its usefulness depends on soil, slope, water, climate and ecological conditions. Competing uses mean that a land-use decision can affect food production, drainage, access and biodiversity at the same time.

Soil as a living system

Soil contains mineral particles, organic matter, water, air and organisms. It supports plant growth, stores and filters water and participates in nutrient cycling. Productive topsoil can be lost rapidly compared with the time required for soil development.

Important distinction

Land is the broader surface and its uses. Soil is the biologically active material that covers much of that surface. Protecting land area alone does not guarantee that soil remains productive.

Land degradation

Land degradation is a decline in the capacity of land to provide useful ecological or productive functions. Erosion, compaction, salinisation, loss of organic matter and unsuitable land use can contribute. These processes differ and need different remedies.

Read the landscape

The terraces shorten and interrupt the slope. Vegetated risers protect exposed faces, while mulch covers soil between plants. These features work with appropriate drainage and maintenance; blocking water indiscriminately can create new erosion or waterlogging problems.

Planning principle

Use land in ways suited to its capability. A steep, erosion-prone slope may need protective cover and carefully assessed use rather than the same treatment as a flat, stable field.

11. Soil Degradation and Control

11.1 Soil Erosion

Soil erosion is the detachment and transport of soil by agents such as water or wind. Runoff may remove a thin layer or develop concentrated channels. Bare surfaces, disturbed soil and steep slopes can increase vulnerability, depending on rainfall, soil properties and land management.

Diagram comparison

• Bare slope: Fast runoff can detach and carry topsoil.
• Protected slope: Protective cover helps reduce surface erosion.

11.2 Other Forms of Degradation

Compaction reduces pore space and can restrict root growth and infiltration. Loss of organic matter weakens soil structure and biological functioning. Salinisation is the accumulation of salts; it can develop under unsuitable irrigation and drainage conditions, especially where evaporation is high.

Match cause to remedy

Planting vegetation may reduce erosion, but it does not by itself solve every salinity or drainage problem. First identify the degradation process, then choose an appropriate measure.

11.3 Conservation Methods

11.4 Land-Use Planning and Restoration

Retain suitable vegetation on vulnerable slopes and stream margins, avoid unnecessary sealing of permeable ground and rehabilitate disturbed sites. Construction areas need planned drainage and erosion control. Measures must not simply divert sediment or flood risk onto neighbouring land.

11.5 Daily-Life Connection

Do not treat campus soil as empty space. Repeated parking or walking on planted ground can compact it and damage roots. Marking paths, protecting existing vegetation and using appropriate mulch can be more useful than repeatedly replacing failed plants without addressing the soil condition.

Exam distinction

Contour farming aligns operations across a slope along lines of equal elevation. Terracing changes the slope into step-like surfaces. They are related conservation approaches, but they are not the same physical treatment.

Memory cue: cover, slow, suit

Cover vulnerable soil, slow erosive runoff where appropriate and suit land use to the site. Add proper drainage and maintenance to the explanation.

12. Energy Resources: Overview

12.1 Solar and Wind Energy

Illustration labels

• Grid connection.
• Wind turbine.
• Rotor blades.
• PV modules.
• Module rows.
• Support structure.

Non-renewable sources

Coal, petroleum and natural gas are fossil resources used for electricity, heat, transport and industrial processes. Their stocks are finite on human timescales, and extraction and use have environmental consequences. Nuclear energy uses fuels such as uranium; it is low-carbon in operation but is not normally classified as renewable.

Renewable sources

Solar, wind, hydropower, geothermal energy and appropriately managed biomass draw on replenished flows or resources. Each has site and management requirements. Hydropower can affect river systems; biomass sustainability depends on feedstock, regrowth and how it is used.

Energy versus electricity

Electricity is one energy form. Transport fuels and direct heating also matter.

Variability and system needs

Sunlight changes with day, season and weather; wind output varies with wind conditions. Electricity systems combine generation, networks, storage, demand management and other sources to supply users. A battery stores energy; it does not create a primary energy source.

Conservation before oversizing

Avoiding waste and improving efficiency can reduce the energy a service requires. Generation choices still need to consider reliability, land, materials, local ecology and maintenance. “Renewable” does not mean that equipment has no manufacturing impact or that every location is suitable.

Exam focus

Identify the source, its renewable/non-renewable classification, main use and one limitation. Keep the overview conceptual.

13. Conserving Energy

13.1 Reduce Demand and Improve Efficiency

Switch off equipment when its service is not required, use appropriate daylight and ventilation, and avoid unnecessary operating hours. Efficiency means obtaining the required service with less energy. Conservation also includes deciding when the service is needed and avoiding needless consumption.

13.2 Familiar Measures

Use efficient lighting suited to the task, maintain appliances, use sensible operating settings and reduce avoidable standby use. Maintain fans, pumps and cooling systems through authorised staff. Insulation and shading can reduce unwanted heat gain where suitable, lowering the work required from cooling equipment.

13.3 Rebound Effect

A more efficient device may be used longer because it seems inexpensive to operate. This can offset part of the expected saving. Evaluate total energy over a stated period, rather than assuming that a lower power rating guarantees lower annual consumption.

Unit distinction

Power is the rate of energy use, measured in watts or kilowatts. Energy over time may be measured in kilowatt-hours. A kWh is an energy unit, not a power rating.

13.4 Worked Electricity Example

Given: Ten 40 W lamps are replaced by ten 18 W lamps that provide suitable illumination. They operate 5 hours per day for 30 days. Estimate the reduction in electricity use, assuming the same operating hours.

Step 1: Initial total power.

10 × 40 W = 400 W = 0.40 kW.

Step 2: New total power.

10 × 18 W = 180 W = 0.18 kW.

Step 3: Power reduction.

0.40 − 0.18 = 0.22 kW.

Step 4: Operating time.

5 × 30 = 150 h.

Step 5: Energy saved.

0.22 × 150 = 33 kWh.

The example compares operating electricity only. It does not by itself calculate manufacturing impacts, actual electricity cost or emissions. Those require additional information. It also assumes the replacement lamps provide acceptable lighting for the same task.

13.5 A Second Interpretation

A 1 kW appliance used for 2 hours consumes 2 kWh. A 0.5 kW appliance used for 6 hours consumes 3 kWh. The lower-power appliance uses more energy in this example because it operates much longer. Always multiply power by time.

Simple campus audit

List selected equipment, its rated power, approximate quantity and operating hours. Mark estimates clearly. Identify lights left on in empty rooms or preventable pumping. Ask staff to check equipment changes and compare energy records after action. Do not open electrical panels or alter installations.

Useful formula

Energy (kWh) = Power (kW) × Time (h).

Convert W to kW by dividing by 1,000. Multiply by the number of devices when their ratings and operating hours are the same.

14. Over-Exploitation of Resources

14.1 Meaning

Over-exploitation is resource use that persistently depletes stocks or damages their capacity to recover and support ecological functions. For a renewable stock, use may exceed replenishment. For a finite resource, rapid extraction accelerates depletion and can intensify associated environmental damage.

14.2 Why It Happens

Rising consumption, inefficient use, avoidable waste, short-term incentives and weak coordination between users can encourage excessive extraction. A shared resource may be especially vulnerable when each user considers only an individual benefit and ignores the combined withdrawals.

Do not oversimplify

“Renewal exceeds use” is a helpful starting idea for a renewable stock, but sustainable management also considers habitat, water quality, seasonal variation and essential ecological functions.

14.3 Examples and Consequences

14.4 A Combined Response

Reduce unnecessary demand, improve efficiency, extend product life and recover suitable materials. Protect recharge areas, soil cover and forest regeneration. Plan extraction with monitoring and the needs of other users in view. One measure rarely resolves every driver.

Shared-well case

Several buildings draw from the same aquifer. Each installs a larger pump after supply becomes less reliable. The total withdrawal may rise even though the aquifer has not gained new recharge. A coordinated water-use review, loss repair and assessment of the shared resource is more useful than assuming that more pumping capacity creates more water.

14.5 Warning Signs versus Proof

Drying shallow wells, shrinking vegetation cover or rising demand may signal a problem, but each observation needs context. Compare conditions through time, record alternative explanations and use appropriate monitoring. A photograph alone cannot quantify a resource balance.

Answer pattern

State the resource, explain the pressure, identify the renewal or quality process being affected, describe the consequence and connect a practical response to that mechanism.

15. The 3 R’s: The Core Idea

15.1 Reduce, Reuse, Recycle

The 3 R’s organise familiar ways to reduce material demand and waste. Reduce avoids unnecessary input. Reuse keeps a product or component in service. Recycle processes discarded material into feedstock for new products. Their priority normally begins with preventing unnecessary consumption.

Prefer preventing waste before processing it.

15.2 Why the Order Matters

A product that is never unnecessarily made can avoid extraction, processing, transport and disposal associated with that extra item. Reusing a serviceable product can delay replacement. Recycling recovers material but still requires collection, sorting and processing, so it is not a substitute for avoiding needless consumption.

One bottle, three decisions

• Reduce: Avoid an unnecessary purchase.
• Reuse: Refill a suitable durable bottle.
• Recycle: Send an accepted discarded bottle through the local recovery system.

15.3 Identifying the Correct R

15.4 Product Reuse and Material Recycling

Repair, refill and sharing can extend useful service without reducing a product to its raw material. Recycling changes the material into a new production input. Shredding, pulping, melting or similar processing is usually a clue that material recovery, rather than direct reuse, is involved.

15.5 Context Still Matters

A durable item needs repeated appropriate use to deliver its intended benefit. Cleaning, transport, safety and the suitability of the item matter. Do not claim that a particular reusable product is always best in every situation without considering how it is actually used.

Short-answer practice

Question: Is buying an unnecessary new item acceptable simply because its package is recyclable?

Answer: Recyclability is only one feature. Avoiding an unnecessary purchase can prevent material demand in the first place, and actual recycling depends on collection and processing.

16. Reduce and Reuse in Practice

16.1 Reduce: Begin Before Purchase

Ask whether an item is needed, whether an existing item can provide the service and whether the quantity is appropriate. Avoid duplicate purchases, excess packaging and food prepared beyond likely demand. Reduction concerns avoidable input, not cutting essential nutrition, hygiene or learning needs.

16.2 Reduce Material Losses

Plan cutting, printing, storage and handling so that usable material does not become waste unnecessarily. Print preview can prevent incorrect copies. Suitable storage can prevent supplies from spoiling. Using the right quantity is often more effective than dealing with a larger waste stream later.

16.3 A Useful Measurement

For paper, count sheets used for a comparable activity before and after a change. For food, record safely measured leftovers under an approved process. Use an appropriate denominator, such as sheets per student, when the number of users changes between observations.

Reduction is visible upstream

If fewer unnecessary sheets are printed, there is less material to collect later. A smaller recycling pile may therefore be a good sign when the same useful task has been completed with less paper.

16.4 Reuse: Keep Useful Products Working

Direct reuse

Use an existing product again for its intended purpose when it remains suitable. Examples include refillable bottles, durable bags, shared reference books and reusable storage boxes. Reuse preserves the product’s function without converting it into raw material.

Repair and maintenance

Repairing a loose fitting, replacing a serviceable component or maintaining a device can extend useful life. The repair must be appropriate to the product. Electrical equipment and specialised devices should be handled by competent staff rather than improvised by untrained users.

Sharing and redistribution

A tool library or book exchange can meet several users’ needs with fewer individual purchases. Clear responsibility for condition, cleaning, return and repair helps the arrangement work. Redistributing an unused item is useful only when another person actually needs and can use it.

Where reuse is unsuitable

Do not turn containers with unknown or hazardous residues into food or drinking-water containers. Single-use medical or contaminated items require their appropriate handling route. Reuse should preserve required performance and hygiene; extending the life of an unsuitable object is not a conservation success.

Repair-or-replace case

A serviceable chair has a loose joint. Competent repair can retain the chair’s function and delay replacement. An unsafe or badly damaged item may require a different decision. The reasoned answer compares condition, repair feasibility and useful service, instead of treating all old items as automatically reusable.

Reuse versus repurposing

Using a jar again for suitable storage is reuse. Turning an unsuitable container into decorative clutter is not necessarily a useful resource saving. The key question is whether it replaces a real need safely and for a worthwhile period.

17. Recycling: Concept and Limits

17.1 Meaning

Recycling recovers material from discarded items and processes it for further production. Examples include recovering paper fibres, remelting collected metal and processing accepted glass or plastics. The route depends on material type, condition, local collection and available processing facilities.

Acceptance depends on the local collection system.

17.2 Why Segregation Matters

Mixing food residues, liquids and unsuitable items with recyclables can reduce recoverable quality and make sorting difficult. Follow the local collector’s accepted-material list and preparation instructions. A material may be technically recyclable but lack a practical collection route in a particular place.

Important distinction

“Recyclable” describes a potential material route. “Recycled” means material has actually passed through recovery and processing. A symbol on packaging does not prove that this happened.

17.3 Keep Material Streams Suitable

17.4 Recovery Is Not Perfect

Some material is lost during collection and processing. Contamination and changes in quality can restrict future uses. Recycling also requires energy and other inputs. It can conserve valuable material, but it does not make endless consumption physically loss-free.

17.5 A Complete 3 R’s Example

For a notebook, first avoid unnecessary pages and duplicate printing. Next use remaining suitable blank pages. Finally send accepted waste paper into a local recycling route. The three actions work together; recycling should not be used as a reason to waste paper earlier.

Common exam mistake

“Reuse and recycling both mean using waste again.”

This is too vague. State whether the product is used directly again or the material is processed into a new production input. Add a matching example to make the distinction clear.

Scope of this unit

Understand recycling as a resource-conservation concept. Detailed waste-treatment technologies, e-waste hazards and pollution-control systems belong to the pollution unit and are not expanded here.

18. Rainwater Harvesting

18.1 A Labelled Rooftop System

Diagram title: Rooftop rainwater harvesting — conceptual section.

Diagram labels

• Roof catchment.
• Leaf screen.
• Gutter and downpipe.
• Filter vessel.
• Covered storage tank.
• First-flush drain.
• Non-potable outlet.
• Optional recharge pit.

Meaning and purpose

Rainwater harvesting is collecting and managing rainwater for useful storage or, where suitable, groundwater recharge. A rooftop system uses the roof as a catchment. It can supplement supply and reduce some runoff, but the benefit depends on rainfall, catchment, losses and actual demand.

Follow the illustrated route

Rain falls on the roof, enters the gutter and moves down the pipe. An initial dirty portion is diverted by first flushing. Subsequent runoff passes through a filter before entering the covered tank. The outlet supplies a suitable identified use.

Arrows and pipes

The pale outlined tubes carry water. Small arrows show flow direction. Thin leader arrows identify components. The first-flush branch drains away from storage; it is not a second supply line to the tank.

Storage and overflow

The covered tank stores water for later use. A controlled outlet and suitable screening help maintain the system. Overflow must have a planned destination. In the illustration it reaches an optional recharge unit; this route is appropriate only after assessing source-water quality and site conditions.

Quality limitation

A first-flush device and basic filter reduce certain debris and sediment; they do not guarantee drinking-water quality. Use requires a suitable quality assessment and treatment where needed. The drawing shows a non-potable outlet and is a concept diagram, not a construction specification.

Explain in five steps

Catch → convey → first flush → filter → store or recharge where suitable.

Include maintenance and a planned overflow.

19. Components and Maintenance

19.1 Why First Flushing Matters

Dust, leaves and other deposits can accumulate between rainfall events. The beginning of runoff can carry this material into the system. First flushing diverts an initial portion. The amount and operation depend on local conditions and design; a universal number of minutes is not appropriate for every roof and storm.

Filter limitation

A filter can clog and cause bypass or overflow if neglected. Its presence is not evidence that water quality remains suitable. Inspection and appropriate cleaning are part of the system, not optional extras.

19.2 Storage or Recharge?

19.3 Routine Care

Before the rainy period, inspect the catchment, gutters, screens, pipe joints and first-flush arrangement. Maintain filters according to design and use. Keep tank covers and screens intact. Check that the overflow route is clear and does not cause erosion or nuisance. Record problems and arrange competent repair.

19.4 Prevent Cross-Connections

Non-potable stored water should be clearly identified and kept separate from drinking-water supplies. Any treatment, plumbing changes or recharge arrangements should be designed and maintained by competent personnel. A basic awareness diagram cannot replace these checks.

Why a system may underperform

Possible causes include blocked gutters, a leaking tank, first-flush water not being diverted, clogged filters, insufficient storage, limited rainfall or demand that is larger than the catchment can support. Diagnose the cause before proposing a larger tank or an extra recharge pit.

Maintenance answer pattern

Name the component, describe the likely failure and state the corrective action.

Example: “Clean the blocked leaf screen so roof runoff can enter the conveyance pipe without uncontrolled overflow.”

A simple maintenance record

20. Simple Rainwater Estimate

20.1 Conceptual Collection Formula

A useful awareness-level estimate is:

Potential collected water (m³) = Rainfall (m) × Catchment area (m²) × Assumed collection factor.

The dimensionless factor represents the stated combined collection losses in this simplified exercise. Actual factors vary with surface, rainfall and system operation.

The helpful conversion is:

1 mm of rainfall on 1 m² = 1 litre before collection losses.

Therefore, using rainfall in millimetres and area in square metres gives litres directly before multiplying by the collection factor.

Worked example: rooftop yield

Given:

• Roof area = 100 m².
• Rainfall for the chosen period = 600 mm.
• Assumed combined collection factor = 0.80.

Step 1: Convert rainfall.

600 mm = 0.60 m.

Step 2: Rain volume on the roof.

0.60 × 100 = 60 m³.

Step 3: Estimated collection.

60 × 0.80 = 48 m³.

Step 4: Convert to litres.

48 × 1,000 = 48,000 L.

The factor 0.80 is an assumption for this example, not a prescribed design value. Use rainfall and demand for the same time period when comparing quantities. Avoid subtracting first-flush losses again if the chosen factor already includes them.

What the result means

48,000 L is a simplified potential collection over the stated period. It is not a tank size, guaranteed supply, groundwater recharge volume or volume that can necessarily be used.

20.2 Storage and Demand Are Different

Timing matters

The same total rainfall can arrive as many small events or a few intense storms. A tank may overflow during a large event and empty before the next. Estimating dependable supply requires a time-based balance of inflow, use, storage and overflow. Annual rainfall alone cannot determine the necessary tank capacity.

Worked example: idealised duration

A tank contains 2,000 L of usable non-potable water. The selected daily demand is 250 L. With no new inflow, leakage or other losses:

Duration = 2,000 ÷ 250 = 8 days.

This estimates how long the stated usable storage meets the stated demand. It does not estimate the next rainfall date or year-round reliability.

Worked example: collection fraction

For the same period, estimated usable rainwater is 48,000 L and selected demand is 80,000 L. If all 48,000 L can actually be stored and used:

Fraction supplied = 48,000 ÷ 80,000 = 0.60 = 60%.

The remaining 32,000 L needs another source. If overflow or timing reduces usable collection, the supplied fraction is lower.

20.3 Keep the Estimate Honest

Record the roof area method, rainfall period, assumed loss factor, storage limit and selected demand. Mark uncertain quantities as estimates. A convincing calculation shows its assumptions and units; adding many decimal places does not make uncertain inputs more accurate.

Self-check

For a 50 m² roof, 100 mm rain and a collection factor of 0.70:

Potential collection = 50 × 100 × 0.70 = 3,500 L.

This is before any storage-and-demand timing constraint not included in the factor.

20.4 Sensitivity to the Assumed Factor

For a 100 m² roof receiving 50 mm of rain, gross rainfall volume is 5,000 L.

A factor of 0.60 gives 3,000 L, while 0.80 gives 4,000 L.

The 1,000 L difference comes entirely from the assumption; it is not evidence that either factor is correct for the roof. Record how a factor was chosen and use an appropriate range when losses are uncertain.

21. Daily Resource-Saving Practices

21.1 Small Actions Need Follow-Through

A conservation campaign should connect an observation to a practical action and a check. Putting up a poster without repairing a known leak leaves the measured loss unchanged. A smaller completed action with verified results is more informative than an impressive claim with no evidence.

Keep essential services working

Saving resources should maintain necessary hygiene, safe lighting, accessible facilities and learning activities. Identify avoidable loss rather than simply asking people to stop essential use.

21.2 A Campus Mini-Audit

Step 1: Define a boundary.

Choose one room, tap group, garden bed or printing activity and a fixed observation period.

Step 2: Record a baseline.

Count items, note operating hours or use an authorised meter record. Mark estimates.

Step 3: Identify one cause of avoidable use.

Separate observed facts from possible explanations.

Step 4: Propose an achievable action.

State who can carry it out and when.

Step 5: Check again.

Compare like-for-like conditions after the action and note limitations.

Connections to the nine streams

Report without invention

Use “observed”, “estimated” and “suggested” accurately. Do not present a constructed example as your field result or claim causation from a short observation with no supporting comparison.

Suggested report headings

• Location and dates.
• Resource and activity.
• Observation method.
• Baseline.
• Suspected cause.
• Proposed action.
• Responsible person.
• Follow-up result.
• Limitations.

If the action has not yet happened, label the result as pending rather than inventing a saving. Keep user numbers, occupancy or weather comparable where they affect consumption.

22. Solved Cases and Model Answers

Case 1: “Renewable Means Unlimited”

Claim: A forest is renewable, so any harvesting rate is acceptable.

Answer: Forest biomass can regenerate only when conditions support growth and recovery. Harvesting or disturbance beyond that capacity reduces stocks and may damage habitat and soil. Conservation considers the rate and method of use, regeneration and ecological functions.

Case 2: New Supply Before Loss Repair

Situation: A campus wants a new water source while an existing tank overflows daily.

Answer: Quantify and repair the avoidable overflow first, then reassess demand and dependable supply. A new source may be needed, but its justification should use the reduced demand after preventable losses are addressed.

Case 3: One Box Labelled “Recycling”

Situation: Food residues, paper, batteries and mixed plastics are put in one collection box.

Answer: The label alone does not create a recycling system. Separate materials according to locally accepted routes, keep batteries and electronics in their designated stream and avoid contaminating recoverable materials. Confirm collection and onward handling.

Case 4: Plantation on Any Open Land

Claim: All open land should be planted densely with trees.

Answer: First identify the original ecosystem, land capability, water availability and current uses. Some open habitats are naturally grasslands or wetlands. Appropriate conservation protects the site’s ecological character rather than assuming that dense tree planting is always the best treatment.

A strong case answer

Identify the mistaken assumption, explain the relevant mechanism and propose a specific response. Avoid replacing one absolute claim with another.

22.1 Long-Answer Outlines

Explain water scarcity and conservation

Define scarcity using quantity, quality, timing and access. Explain natural and human causes, then describe effects on people and ecosystems. Match measures to causes: prevent leaks and overflow, manage demand, protect sources and assess suitable rainwater harvesting. Conclude with the need to monitor results rather than claim that one measure solves every shortage.

Explain the 3 R’s with examples

Define Reduce, Reuse and Recycle separately. Explain their usual priority. Use one product to compare them: avoid unnecessary printing, use suitable blank sides, then recover accepted paper through recycling. Mention that recycling requires collection and processing and does not justify avoidable consumption.

Explain rooftop rainwater harvesting

Define the concept. Draw the catchment, conveyance, first-flush branch, filter, covered storage, outlet and overflow. Explain the water route in sequence. Distinguish storage from assessed recharge and state that basic filtration does not guarantee potable water. Add maintenance and local suitability.

Case 5: measured water saving

Before a change, a 20-student activity uses 100 L. After the change, a comparable 25-student activity uses 110 L.

Before:

100 ÷ 20 = 5 L/student.

After:

110 ÷ 25 = 4.4 L/student.

Per-student reduction:

5 − 4.4 = 0.6 L/student, or 12%.

Total water increased by 10 L because participation changed. Report both facts; the denominator changes the interpretation.

Use evidence with limits

The last example compares two stated activities. It does not prove that the same saving will occur every day. Repeat under comparable conditions before making a broader claim.

23. Quick Revision

Formulas worth remembering

Stock balance:

Final = Initial + Additions − Withdrawals, including other relevant flows.

Flow volume:

Volume = Rate × Time.

Electricity:

kWh = kW × Hours.

Rainwater estimate:

Litres = Rainfall (mm) × Area (m²) × Assumed collection factor.

Percentage reduction:

(Initial − Final) ÷ Initial × 100, for comparable quantities.

Three common traps

• Renewable does not mean unlimited.
• Recyclable does not mean actually recycled.
• Potential rainfall collection does not determine tank capacity or guarantee dependable supply.

23.1 Possible Exam Questions

Short-answer questions

1. Define natural resources with four examples.
2. Distinguish renewable and non-renewable resources.
3. Explain why a renewable resource can be depleted.
4. Define water scarcity and list its main drivers.
5. Distinguish infiltration and groundwater recharge.
6. State two benefits of forests beyond timber.
7. Distinguish soil erosion and land degradation.
8. Explain Reduce, Reuse and Recycle.
9. State the purpose of first flushing.
10. Distinguish rainwater storage and recharge.

Long-answer and diagram tasks

1. Explain water scarcity, its effects and practical conservation measures.
2. Discuss forest and land resources and their conservation.
3. Explain over-exploitation with two resource examples and a cause-based response.
4. Explain the 3 R’s with a comparison table and everyday examples.
5. Draw and explain rooftop rainwater harvesting, including maintenance and limitations.
6. Plan a small campus resource-use observation with a baseline, action and follow-up.

Numerical practice

Q1: A 0.10 L/min leak continues for 24 h. Daily loss?

Answer: 144 L.

Q2: A 0.25 kW device operates 4 h/day for 20 days. Energy?

Answer: 20 kWh.

Q3: A 75 m² roof receives 200 mm rain; factor 0.80. Potential collection?

Answer: 12,000 L.

Q4: Use falls from 500 L to 400 L under comparable conditions. Reduction?

Answer: 20%.

Unit II complete

You should now be able to explain resource types, diagnose avoidable use, select justified conservation measures and describe a rainwater-harvesting system with correct labels, units and limitations.

Study Resources

Use these Environment and Sustainability Unit 2 Notes for complete unit study, labelled diagrams, resource-saving calculations, campus activities and examination revision.

Additional unit-wise resources are available at www.notesgallery.com.

The university website is https://aktu.ac.in.

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