Water moves continuously between the sea, the air and the land. This is the water cycle, and it is driven by the sun. This chapter explains evaporation, condensation, clouds, precipitation, the types of rainfall and the rain-shadow region, with examples from Maharashtra.
Key points
About 71% of Earth's surface is water. Its total amount stays almost constant, but it keeps changing between solid, liquid and gas.
Evaporation: the sun's heat turns water from seas, lakes and soil into vapour. It is faster at higher temperature and over a larger surface area. Plants release vapour through leaves (transpiration).
Condensation: rising vapour cools, collects on fine dust particles (condensation nuclei) and forms droplets and clouds. The temperature at which air becomes saturated (100% relative humidity) is the dew point.
Clouds: cumulonimbus (huge, causes thunder, lightning and storms) and nimbostratus (dark grey, heavy rain).
Precipitation: rain, snow or hail, falling when droplets grow too heavy to float. "Monsoon" comes from the Arabic word mausam (season).
About one-third of the water that falls returns to the sea as runoff; two-thirds goes back to the air by evaporation and transpiration.
Convectional (ascending): heated air rises, cools and rains; common every afternoon near the equator.
Relief or orographic (resistance): moist winds are blocked by mountains, rise and rain on the windward side. This is the most common type in the world.
Cyclonic (periodic): rain from cyclonic systems.
Types of rainfall:
In Maharashtra the Western Ghats get heavy relief rain.
Much of Marathwada is a drought-prone rain-shadow area.
Vidarbha's rain is more certain.
Rain-shadow region: the leeward side of the mountains gets little rain.
Some water seeps into the ground and becomes groundwater; the rest runs off into rivers and lakes.
Important terms
Water cycle – continuous circulation of water from ocean to air to land and back.
Dew point – the temperature at which air becomes saturated and vapour condenses.
Transpiration – loss of water vapour from plant leaves.
Rain-shadow region – a low-rainfall area behind a mountain range.
The continuous movement of water from oceans to the atmosphere, to land and back to the oceans, through evaporation, condensation, precipitation and runoff.
Q2. Which factors affect evaporation?
Temperature (higher means faster) and surface area (larger means faster).
Q3. What is the dew point?
The temperature at which unsaturated air becomes saturated and its vapour starts condensing.
Q4. Explain relief (resistance) rainfall.
Moist winds blocked by mountains rise, cool and condense, causing heavy rain on the windward slopes, as on the Western Ghats.
Q5. Why is Marathwada drought-prone?
It lies in the rain-shadow region of the Western Ghats, where the winds have already lost most of their moisture.
Exam tip
Draw and label the water cycle diagram; it earns easy marks.
When rain is more than the ground can absorb, the extra water flows downhill as runoff. Small streams join to form rivulets, tributaries and rivers; together these make a river system. This chapter covers how rivers form, the types of rivers, the landforms they create, river ecosystems and the uses of rivers.
Key points
Formation: brooklets (ohol) join to form rivulets (odhe) and runnels (nale), which join to form tributaries and then the river. Near its source the bed is narrow and steep; near the sea it is wide and gentle.
Noisy (youthful) river: fast, on steep slopes, with a narrow deep bed that it keeps eroding; found in highlands.
Slow river: gentle slope, wide basin; found on plateaus.
Old river: very low slope with no power to erode; found near the sea.
Revived river: dried up, then flows again after the land is uplifted.
Living (perennial) river: fed by springs and groundwater, flows all year.
Dead (seasonal) river: stops flowing when the rains stop.
Types of rivers:
Flow is measured in cusecs (cubic feet per second; 1 cusec ≈ 28.3 litres per second).
Erosional landforms: V-shaped valleys, gorges, waterfalls and potholes.
Depositional landforms: flood plains, levees, meanders, ox-bow (horseshoe) lakes and deltas, such as the Ganga–Brahmaputra delta.
Silt islands form in the Godavari, Bhima and Krishna and are very fertile.
Ghats are the wide stone steps on river banks. A river vortex is the whirling of water at a sudden drop.
River ecosystem: plants, fish and other organisms that depend on the river.
Uses: drinking water, irrigation, industry, power, cheap transport (river navigation is known from the Indus civilisation, about 3300 BC), floating timber, fishing, and as borders.
River sand is used in construction, but excessive sand mining damages the river.
Important terms
Runoff – rainwater flowing over the surface.
Tributary – a smaller river joining a main river.
Delta – a triangular area of fertile silt at a river's mouth.
Meander – a snake-like bend in a slow river.
Key facts
Brooklet → rivulet → tributary → river → sea.
1 cusec = 1 cubic foot per second ≈ 28.31 litres per second.
Silt islands: Godavari, Bhima, Krishna.
5 important questions
Q1. What is a river system?
A main river with all the brooklets, rivulets and tributaries that flow into it.
Q2. Distinguish between a living river and a dead river.
A living river flows all year, fed by springs and groundwater; a dead river stops flowing when the rains stop.
Q3. What is a noisy river?
A river near its source that flows fast down steep slopes in a narrow, deep bed, eroding it constantly.
Q4. Name landforms created by river erosion and by river deposition.
A watershed (catchment area) is all the land that drains its rainwater into a stream or river. This chapter explains watershed sizes and properties, the features of rainfall that affect runoff and erosion, the types of groundwater layers (aquifers), surface water, and how water is distributed on Earth.
Key points
Watershed (catchment area): the whole area from which rainwater flows into a given stream or river. Small watersheds join to form larger ones and finally a river valley.
Classification by area: micro (up to 10 ha), mini (up to 200 ha), sub-watershed (up to 4000 ha), river valley (no limit).
Shape and size: a long, narrow watershed releases water slowly, so more of it seeps in.
Slope: steep slopes give fast runoff and less seepage.
Ground cover: grass and forest reduce erosion.
Drainage density, land use, infiltration, soil type and depth, and geology.
Properties that matter:
Rainfall features: amount (mm), annual average, frequency, distribution, the length of a rainy spell and intensity (mm per hour, measured with a self-recording rain gauge). Heavy-intensity rain is short and infrequent.
Unconfined aquifer: near the surface, pores hold air and water, affected by atmospheric pressure.
Confined aquifer: a saturated layer sealed between other layers. If water rises by itself when a well is dug, it is a fountain (artesian) well.
Groundwater is water stored in soil pores and rock cracks below the surface.
Aquifer: sand, gravel; stores and gives water.
Aquitard: semi-permeable; gives water slowly.
Aquiclude: clayey soil; holds water but does not give it.
Aquifuge: hard rock such as granite or basalt; neither holds nor gives water.
A hanging (perched) aquifer sits above the unsaturated zone.
Layers by water-giving ability:
Surface water: permanent (rivers, lakes), temporary (seasonal creeks) and man-made (dams). Maharashtra has about 1821 large dams.
Distribution: about 97% of Earth's water is salty sea water and only about 3% is fresh. Most fresh water is locked in ice and glaciers; a small share is groundwater, and rivers and lakes are a tiny part.
Important terms
Watershed – the land area draining into one stream or river.
Aquifer – a permeable layer that stores and yields groundwater.
Rainfall intensity – rainfall in mm per hour.
Artesian (fountain) well – a well where water rises by natural pressure.
Key facts
Type
Area
Micro
up to 10 ha
Mini
up to 200 ha
Sub-watershed
up to 4000 ha
River valley
no limit
5 important questions
Q1. What is a watershed?
The whole land area from which rainwater flows into a particular stream or river.
Q2. Classify watersheds by area.
Micro (up to 10 ha), mini (up to 200 ha), sub-watershed (up to 4000 ha) and river valley (no limit).
Q3. How does slope affect a watershed?
On steep slopes water runs off quickly with little seepage; on flat land it moves slowly and more soaks in.
Q4. Distinguish between an aquifer and an aquifuge.
An aquifer (sand, gravel) is permeable and stores and gives water; an aquifuge (granite, basalt) neither holds nor gives water.
Q5. What is a fountain well?
A well where water rises to the surface by natural pressure from a confined aquifer.
Exam tip
Learn the four-layer table (aquifer, aquitard, aquiclude, aquifuge) with an example of each.
The rocks under our feet decide how much groundwater an area can store. Maharashtra is mainly made of layers of black basalt formed from ancient lava flows. This chapter explains these rock layers, porosity and permeability, how rocks weather into soil, soil particle types, humus and why soil matters.
Key points
Each layer is 5–35 m thick, with a compact lower part and a porous upper part holding green-white amygdales ("manjrya").
A 1–5 m reddish red bole (ochre) layer often lies between two basalt flows; in places there is grey volcanic ash.
Black basalt: formed when lava erupted and cooled in horizontal layers (the Deccan Traps, about 65 million years ago).
Other rocks in Maharashtra: laterite (jambha), limestone, sandstone and loam formed from basalt.
Porosity: the share of empty spaces in a rock's volume. Compact basalt has 0.14–1%, sandstone 10–30%, and clay or sandy silt 45–50%.
Permeability: the ability to let water pass through. Clay is very porous but hardly permeable; for groundwater, permeability matters more than porosity.
Fractures: cracks in basalt caused by heat, cold, rain, chemical action and pressure. Groundwater moves through them.
Weathering: rocks break into fine particles and become soil through changes in air, water, temperature and pressure.
Soil particles: clay (finest, under 0.002 mm), silt (0.002–0.05 mm), sand (about 0.05–2 mm) and gravel or stone (over 2 mm). Soil also contains organic matter.
Importance of soil: supports plants, supplies minerals and nutrients, stores water and is home to useful microorganisms.
Humus: microbes decompose plant and animal remains into nitrogen-rich matter that improves fertility.
About 800–1000 years are needed to form 2.5 cm of fertile soil naturally, so soil must be conserved.
Important terms
Porosity – the percentage of empty space in a rock or soil.
Permeability – the ability of a rock or soil to let fluids pass.
Weathering – the breaking down of rocks into soil.
Humus – decomposed organic matter in soil.
Key facts
Material
Porosity
Compact basalt
0.14–1%
Sandstone
10–30%
Red bole
about 35%
Clay
45–50%
5 important questions
Q1. How is black basalt formed?
Lava from volcanic eruptions spread over the land and cooled in horizontal layers.
Q2. Distinguish between porosity and permeability.
Porosity is the amount of empty space in a rock; permeability is how easily water passes through it. Clay has high porosity but low permeability.
Q3. What is weathering?
The breaking of rocks into fine particles by changes in temperature, air, water and pressure, which finally forms soil.
Q4. Name the types of soil particles.
Clay, silt, sand and gravel or stone.
Q5. Why should soil be conserved?
Fertile soil forms very slowly (about 2.5 cm in 800–1000 years) and supports plants, stores water and holds nutrients.
Exam tip
Remember "porosity ≠ permeability" with the clay example; it is a favourite reasoning question.
People have long built structures to store and draw water, from simple wells to stepped baravs, temple ponds and village lakes. This chapter describes the types of wells, ponds and lakes, farm ponds, and the bodis of Vidarbha.
Key points
Well: a pit dug down to the groundwater level, lined with stone, brick or concrete. Water is drawn with a pulley (moat) or a pump.
Aad: narrow, deep, often square; used where groundwater is very deep.
Kup: narrow and deep, not square.
Round well: the most common; square and elongated wells are similar.
Tube well: pipes reach deep water; used where loose soil keeps caving in. Cheap and space-saving, but stores less.
Pushkarani: a square, stepped stone pond, usually at temples and palaces.
Barav: a large stepped well of fine stonework. The Baramot well at Limb (Satara) is from the Shivaji Maharaj era and has 12 pulleys.
Budki: holds water only in the rains; common in tribal areas of the Sahyadri.
Bore well: drilled where groundwater is deep. It is now over-used and misused.
Ring well: concrete rings 10–20 ft deep; good near the coast and for urban rainwater conservation.
Types of wells:
Uses: village water supply, temples, religious rites, firefighting, travellers.
Examples: Rajsamand (Udaipur), Anasagar (Ajmer), the Golden Lotus tank (Madurai), Mariamman Teppakulam (1645). Some Mumbai lakes were later filled in.
Ponds and lakes: smaller than lakes but larger than wells, also called talav or vapi. Building one for the public was once considered a sacred duty.
Best on clayey black soil with low permeability; unsuitable on sandy, porous or saline land.
Also useful for fish farming and recharge.
Farm pond: dug on the upper side of a farm to store runoff for crops in dry spells.
Bodi: a small earthen reservoir above paddy fields in east Vidarbha (Bhandara, Gondia, Chandrapur, Gadchiroli) that gives protective irrigation. Old bodis are being desilted and renewed.
Important terms
Barav – a large stepped stone well.
Pushkarani – a stepped temple pond, traditionally a lotus pond.
Farm pond – a pond dug on a farm to store rainwater runoff.
Bodi – a traditional small reservoir for paddy in Vidarbha.
Key facts
Baramot well: Limb, Satara district (12 pulleys).
Bodis: Bhandara, Gondia, Chandrapur, Gadchiroli.
Ring well depth: 10–20 ft.
5 important questions
Q1. What is a well? Name four types.
A pit dug to reach groundwater. Types: round well, aad, tube well and barav (also bore well and ring well).
Q2. What is a bodi?
A small earthen reservoir built above paddy fields in east Vidarbha to give water to rice in an emergency.
Q3. Where should a farm pond be built?
On the upper side of a farm, on low-permeability clayey black soil, along natural furrows or the sloping banks of a stream.
Q4. Give four uses of ponds and lakes.
Village water supply, religious activities, firefighting and groundwater recharge.
Q5. Why is the overuse of bore wells a problem?
They are cheap and quick, so too many are drilled; deep groundwater is over-pumped and water tables fall.
Exam tip
Match each structure to its region or feature (budki – Sahyadri, bodi – Vidarbha, barav – stepped well).
Rain falls for only a few months, unevenly and more erratically because of climate change, yet we need water all year. Water conservation means catching rainwater where it falls, storing it or sending it into the ground, so that it lasts until the next monsoon. This chapter covers why it is needed and how it works in cities and villages.
Key points
Rainwater partly seeps into the soil, is stored as surface water, evaporates, is used by plants, or runs off.
Rain now comes in short heavy bursts with long dry gaps, so less of it seeps in.
Deforestation lets water rush off the land.
Springs and wells dry up soon after the monsoon, and some areas face constant drought.
Why the need is growing:
Definition: water conservation uses man-made structures to stop, store and infiltrate rainwater in an area so it can be used for drinking, homes, industry and farming until the next monsoon.
Concrete and paving cut infiltration; open soil absorbs about 50% of the rain, concrete hardly 10%.
Roof water goes into drains and out to the sea, causing floods in the monsoon and scarcity in summer.
Cities:
Temporary use: store enough for 4–5 days during the rains.
Post-monsoon use: store in tanks or recharge wells and bore wells.
Rainwater harvesting: diverting, infiltrating and storing rainwater on the spot.
Strengthens sources and improves water quality.
Extends the life of wells and bore wells, and reduces salts in bore-well water.
Prevents waterlogging and floods.
Makes an area self-sufficient in water.
Benefits:
Villages: plan from the population, the need for drinking water, cattle and crops, the sources, soil, rock and slope. Long-term success needs local participation.
Wider gains: sustainability (pump less than the recharge), energy saving (about 15% of electricity goes into water management) and habitat protection.
Old forts (sea, land and hill forts) used tanks, wells and ponds to store rain, an example from history.
Important terms
Water conservation – storing and infiltrating rainwater for use until the next monsoon.
Rainwater harvesting – collecting and storing or recharging rainwater where it falls.
Runoff – rainwater flowing away over the surface.
Key facts
Open soil absorbs about 50% of rain; concrete hardly 10%.
About 15% of electricity is used for water management.
Two kinds of harvesting: temporary and post-monsoon.
5 important questions
Q1. What is water conservation?
Using man-made measures to stop, store and infiltrate rainwater in an area so it can be used until the next monsoon.
Q2. Why is water conservation needed more today?
Rainfall is erratic, with heavy bursts and long dry spells; deforestation and concreting increase runoff; and demand keeps rising.
Q3. How does concreting affect cities?
It reduces infiltration from about 50% to about 10%, causing floods in the rains and scarcity in summer.
Q4. State four benefits of rainwater harvesting.
It strengthens sources, improves water quality, extends the life of bore wells and prevents flooding.
Q5. Name the two types of rainwater harvesting.
Temporary use during the rains (4–5 days of storage) and storage or recharge for use after the monsoon.
Exam tip
Use the 50% versus 10% infiltration figures to explain urban flooding; they show clear understanding.
Catchment (watershed) treatment means slowing rainwater and letting it soak in across the whole catchment, from the hilltop to the stream. This chapter covers in-situ treatments on land (farm bunds, terraces, contour trenches) and stream treatments (loose boulder, gabion, earthen, cement and diversion check dams, and stream deepening).
Key points
Aim: prevent soil erosion, increase infiltration, recharge groundwater and give protective irrigation to crops.
Farm bunding: embankments in sloping fields keep rainwater and soil in the field (main bunds across the slope, side bunds along it).
Sloping or level check dams (earthen or vegetative) along fields slow the flowing water rather than store it.
Terraces (bunds on slopes): hill slopes cut into steps for farming, e.g. paddy on the slopes of rain-fed Maharashtra.
Contour trenches: level trenches on fallow slopes (0–33%), 0.60 m wide and 0.30–0.45 m deep. About 180–270 m³ of water is stored per 1000 running metres.
Deep continuous contour trenches (CCT): 1 m × 1 m, about 240 m per hectare, rows 33 m apart, with grass sown along them.
A. In-situ (on-the-spot) treatment:
Loose boulder structure: natural rough stones across small streams in the upper catchment slow the flow and reduce erosion.
Gabion check dam: stones packed in galvanised wire mesh, keyed 2 m into the banks; used where the slope or the rain is too strong for loose stones.
Earthen nala bund: controls gully widening and floods; stops water so it seeps in and wells rise. Used for catchments of 10–40 ha and 40–500 ha.
Cement concrete nala bund: durable and leak-proof; raises well and groundwater levels.
Stream deepening: removing silt from filled check dams restores storage.
Diversion check dam: a paved bund that diverts stream flow to fields, common in the Konkan and Ghat areas where streams flow till December–January.
B. Stream (drainage line) treatment:
Treatment works best from ridge to valley: the top of the catchment first, then downstream.
Important terms
Catchment treatment – soil and water conservation works across a watershed.
Contour – a line joining points of equal height on a slope.
Gabion – a wire-mesh cage filled with stones.
Nala bund – a check dam built across a stream.
Key facts
Structure
Main material
Loose boulder
rough stones
Gabion
stones in wire mesh
Nala bund
earth
CNB
cement concrete
5 important questions
Q1. What is catchment treatment?
Measures that slow down rainwater and help it soak in across a catchment, preventing soil erosion and supporting irrigation.
Q2. What is a contour trench?
A level trench dug along the contour of a fallow slope to store runoff, let it infiltrate and reduce erosion.
Q3. Why are gabion check dams built?
Where slopes are steep or rainfall heavy and loose stones would be washed away; the mesh holds the stones firmly.
Q4. State the benefits of an earthen nala bund.
It controls gully widening and floods, recharges groundwater, raises well levels and gives water for crops and cattle.
Q5. What is a diversion check dam?
A paved dam across a stream that diverts its flow into fields, giving crops running water as long as the stream flows.
Exam tip
Divide your answer into in-situ and stream treatment; examiners look for this classification.
Groundwater is being pumped out faster than rain can refill it, so many wells and bore wells now run dry or go 400–500 ft deep. Groundwater recharge means helping rainwater seep into the ground in a planned way. This chapter explains why recharge is needed, the precautions, a rainwater calculation, and recharge pits and filters.
Key points
Recharge: infiltrating rainwater into the soil in various ways to increase groundwater storage.
Extraction is greater than natural recharge, so water tables fall.
Concrete in cities blocks natural seepage.
Every bore well should be recharged, or it may suddenly dry up.
Why needed:
Natural seepage is greater on gentle slopes and on porous, jointed or fractured rocks; it is lower on steep slopes.
Filter rainwater before recharge, because it may be acidic and roofs may be dirty.
Let the first one or two showers go to waste.
Polluted surface water can be treated, but a contaminated aquifer is almost impossible to clean.
Precautions:
Plot of 500 m²: 500 × 2.2 = 1100 m³ (11 lakh litres); at 60% capture, 6.6 lakh litres.
Roof of 100 m²: 100 × 2.2 = 220 m³; at 80% capture, 1.76 lakh litres.
At 10 litres of drinking water per person per day, the roof water alone serves about 50 people for a year.
Rainwater mathematics (book example: 2.2 m annual rain):
Recharge (soak) pit: layers of large stones at the bottom, then small stones, coarse sand and fine sand on top. A 3–4 inch pipe carries the filtered water to a well, bore well or the ground.
Sand filter: layers of gravel and sand over a porous base.
Coal filter: like a sand filter, with a fine charcoal layer.
Pipe filter: a 140 mm × 1.2 m pipe with graded gravel layers.
Filters:
Roof-water harvesting: either store it in a closed tank (filter it and chlorinate before drinking) or send it into the ground through a soak pit.
Recharge also prevents waterlogging and local flooding.
Important terms
Groundwater recharge – adding water to underground aquifers.
Soak (absorption) pit – a pit with stone and sand layers that filters and infiltrates water.
Water table – the upper level of saturated ground.
Key facts
Volume of rainwater = area × rainfall.
1 m³ = 1000 litres.
Capture: about 60% from open ground, about 80% from roofs.
5 important questions
Q1. What is groundwater recharge?
Infiltrating rainwater into the ground in planned ways to increase groundwater storage.
Q2. Why should the first showers not be used for recharge?
They wash dust and dirt off roofs and may be acidic; contaminated groundwater cannot be purified.
Q3. Calculate the rainwater from a 100 m² roof with 2.2 m of rainfall at 80% capture.
Water is the base of all life, and civilisations grew beside rivers. This chapter explains why Maharashtra is a water-scarce state by the Falkenmark criteria, asks whether drought is natural or man-made, and shows how over-pumping of groundwater and river pollution make the problem worse.
Key points
Earth is called Bahuratna Vasundhara (the land of many gems), and water is its most important gem. All living things are made mostly of water.
Ancient civilisations such as Mesopotamia, Egypt and Harappa grew on river banks.
Above 1700 m³: good water condition.
Below 1000 m³: scarcity harms living standards.
Below 500 m³: severe scarcity, a problem even for animals.
Falkenmark criteria (written "Falcon" in the book), per person per year:
Maharashtra has only about 788 m³ per person per year, so it is a water-scarce state.
Some villages grow water-hungry sugarcane while others need tankers.
There are "wet droughts" with heavy rain but no drinking water.
Much of the scarcity comes from how water is used and managed.
Drought, natural or man-made? Maharashtra has good rainfall and many dams, yet:
Tube wells go 400–500 ft deep.
In India, 65% of irrigation water and a large share of domestic water come from wells.
Flood irrigation of whole fields wastes water, and water tables keep falling.
Over-pumping of groundwater:
River health: cities and industries on river banks release sewage and factory waste; springs close up and over-pumping stops river flow. Polluted rivers need to be revived.
Careful, responsible use of water is everyone's duty.
Important terms
Water scarcity – too little water per person to meet needs.
Per capita availability – water available per person per year.
Wet drought – drinking water is lacking despite rain.
Groundwater abstraction – pumping water out of the ground.
Key facts
Per capita per year
Condition
> 1700 m³
good
< 1000 m³
scarcity
< 500 m³
severe scarcity
Maharashtra ≈ 788 m³
water-scarce
5 important questions
Q1. Explain the relationship between water and living things.
All organisms are made largely of water and need it to live; human settlements and civilisations grew near water.
Q2. How is water scarcity classified by the Falkenmark criteria?
Above 1700 m³ per person per year is good, below 1000 m³ is scarcity, and below 500 m³ is severe scarcity.
Q3. Why is Maharashtra called water-scarce?
Only about 788 m³ of water is available per person per year, below the 1000 m³ level.
Q4. Why is groundwater getting depleted?
Deep tube wells pump out more than is recharged, and wasteful flood irrigation uses far more water than needed.
Q5. How does urbanisation affect river health?
Cities and industries dump sewage and waste into rivers, and over-pumping dries their springs, so rivers become polluted and stop flowing.
Exam tip
Learn the three Falkenmark limits and Maharashtra's 788 m³; they are asked as short notes.
We use water for our homes, farms, industry, power, fishing, shipping, tourism and the environment. This chapter shows how domestic water is split between uses, explains water use in agriculture, industry and hydropower, and stresses that nature also needs water.
Principle: "water for the crop, not for the whole land", so irrigate as each crop needs, using modern methods.
Water Users' Associations share canal water fairly among farmers.
Agriculture uses the most water.
Industry: agro-based (sugar factories, fruit processing) and non-agricultural (factories, construction of roads, dams and colonies).
Hydroelectric power: water falling from a height turns turbines. Maharashtra projects include Koyna, Popkhali, Bhira, Bhivpuri, Khopoli, Warna and Vaitarna.
Fishing and fisheries: in the sea, creeks, rivers, dams and farm ponds. Fish farming is a good side business for farmers.
Shipping: the cheapest transport. Major Indian ports include Kandla, Mumbai, Kochi, Visakhapatnam and Chennai; the Suez and Panama Canals and the North Atlantic are major world waterways.
Tourism: water attracts tourists (Dnyaneshwar Udyan at Paithan on the Jayakwadi project, Anand Sagar at Shegaon). Reservoirs like Ujani (Maharashtra) and Bharatpur (Rajasthan) draw migratory birds.
Environment: forests, wildlife and food chains need water; it keeps nature in balance.
Important terms
Domestic consumption – water used in homes.
Hydroelectricity – electricity made from falling water.
Water Users' Association – a farmers' group that manages irrigation water fairly.
Key facts
Domestic use
Share
Toilet
24%
Bathing
20%
Cooking
20%
Washing clothes
17%
Tap leaks
12%
5 important questions
Q1. State the types of water consumption.
Domestic, agricultural, industrial, power generation, fisheries, shipping, tourism and environmental.
Q2. How do we use water at home?
For drinking, cooking, bathing, washing clothes and dishes, toilets and cleaning; toilets use the largest share.
Q3. What does "water for the crop, not for the whole land" mean?
Give each crop only the water it needs, using methods like drip and sprinkler instead of flooding the field.
Q4. Name four hydroelectric projects in Maharashtra.
Koyna, Bhira, Warna and Vaitarna.
Q5. Explain the relationship between water and environmental protection.
Plants, animals and food chains depend on water; it maintains the balance of living and non-living elements in nature.
Exam tip
Remember that the toilet (24%) is the largest domestic use and tap leaks waste 12%; easy saving ideas follow from these.
The tap water in our homes makes a long journey: from the dam to a lifting station, through a treatment plant, into storage tanks and finally through pipes to each house. This chapter explains that journey, how a city's water supply is planned, and how water is purified.
Key points
Dams are sited after studying the catchment, rainfall and water needs. The world has about 45,000 large dams, about 22,000 of them in China; India has about 4200.
Canals carry water from a dam to where it is needed; sub-canals take it from the main canal to farms.
The site should keep water quality safe, simplify distribution, have power and be safe from floods and fire.
Extra pumps are kept as standby.
Water lifting (intake) station: draws water from a river, canal or reservoir and pumps it to the treatment plant.
Choose a source and check its quantity and quality.
Estimate the future population and demand per person, including industry and firefighting.
Survey the city and catchment.
Plan how to carry the water.
Design the purification.
Plan the storage tanks and pipelines.
Choose the cheapest acceptable plan and build it in phases.
Planning a city's supply:
Big cities fetch water from far away; Mumbai, for example, from the Tansa and Vaitarna lakes. Coastal cities may have to desalinate seawater in shortages.
Why purify: raw water carries salts, minerals, organic matter, larvae and germs. Household water must be colourless, odourless, tasty and safe. Excess fluoride harms children's teeth.
Aeration: removes CO₂, H₂S, bad taste and iron or manganese, and adds oxygen.
Chemicals (alum) are mixed in and churned.
Sedimentation lets the sludge settle.
Filtration.
Disinfection (chlorination).
Testing.
The clean water is stored in overhead tanks and supplied through mains and pipes.
Purification steps:
Cities on rivers (Pune, Solapur, Delhi) must place intakes away from sewage outfalls.
Important terms
Water treatment plant – where raw water is made drinkable.
Aeration – mixing air into water to remove gases and add oxygen.
Disinfection – killing germs, usually with chlorine.
Intake (lifting) station – the structure that draws raw water from a source.
Key facts
About 71% of Earth's surface is water.
Large dams: about 45,000 in the world, 22,000 in China, about 4200 in India.
Order: dam → intake → treatment → storage tank → pipes → home.
5 important questions
Q1. What is a water lifting station?
A structure that draws water from a river, canal or reservoir and sends it to the treatment plant.
Q2. Why must water be purified?
Raw water contains dissolved and suspended impurities and germs that cause disease and harm industry and crops.
Q3. Write the steps of water purification.
Aeration, adding chemicals and mixing, sedimentation, filtration, disinfection and testing, then storage and supply.
Q4. What is aeration and why is it done?
Mixing air into water to remove gases like CO₂ and H₂S, bad taste, and iron or manganese, and to increase dissolved oxygen.
Q5. Distinguish between a canal and a sub-canal.
A canal carries water from the dam towards an area; a sub-canal branches from the main canal to supply individual farms.
Exam tip
Write the dam-to-home journey as a flow chart; it scores well.
Managing water is like managing a family budget: you must know what comes in, what goes out and what is truly needed. Water management means sharing water fairly between drinking, farming and industry. This chapter lists Maharashtra's water challenges and ten practical measures to solve them.
Key points
Management is the planned use of tasks, facilities and human and material resources. It involves planning, organising, coordinating, supervising and controlling.
History: water was first used for drinking, then for farming, and after the Industrial Revolution for industry. Dams increased supply, but demand keeps rising.
Definition: water management allocates water on the principle of equal justice among drinking, agriculture and industry, based on the real need, availability and use.
Maharashtra's challenges: improper and excessive use, unequal distribution, poor planning, drought, pollution, under-used irrigation capacity and growing demand.
Groundwater recharge of wells and tube wells.
Water conservation: recharging wells, deepening and widening nallas, small diversion dams. It is a lasting answer to drought.
Stop pollution: no rituals or immersion in drinking-water sources; treat industrial waste and sewage, then reuse.
Economical farm use: drip, sprinkler and micro irrigation (with 75–100% subsidy suggested), mulching around fruit trees and pruning in scarcity.
Public participation: campaigns such as Tanker Mukti and Jalsamruddh Gram, on the lines of the Sant Gadgebaba Gram Swachhata Abhiyan.
Sewage recycling: Israel gets about 21% of its water from recycled wastewater, used in farming.
Full use of irrigation capacity: finish canals on time, line canals with cement, use pipes and automatic gates.
Water audit: meters and billing by use, higher rates for heavy users, measuring devices on projects.
Water literacy: knowing and practising the careful use of water.
Cooperation among the government, NGOs, the media and citizens.
Measures:
Important terms
Water management – fair, planned allocation and careful use of water.
Water audit – measuring water supplied and used to find losses.
Water literacy – awareness and practice of wise water use.
Key facts
Three sectors: drinking, agriculture, industry.
Israel: about 21% of its water comes from recycled wastewater.
Drip and sprinkler irrigation save water.
5 important questions
Q1. What is water management?
The fair, planned allocation of water among drinking, agriculture and industry, based on real need, availability and use.
Q2. Why is water management needed today?
Population growth, rising living standards, farming and industry have increased demand while sources are shrinking and polluted.
Q3. How can water be used economically in agriculture?
By drip, sprinkler and micro irrigation, mulching around trees and lining canals or using pipes to stop seepage.
Q4. What is a water audit?
Measuring water supply and use through meters and devices, billing by use, so that losses are found and water is used carefully.
Q5. How does public participation help water management?
People take part in conservation, recharge and campaigns like Tanker Mukti, so projects succeed and water is used wisely.
Exam tip
List the measures with short headings; long-answer questions reward a numbered list.
Clear-looking water is not always safe. Water quality depends on the dissolved physical, chemical and biological substances in it. This chapter explains how water gets polluted, the key quality measures (pH, dissolved oxygen, BOD, COD), the Indian drinking-water standards, and Singapore's "NEWater" recycling.
Key points
Water quality depends on the amount of dissolved substances. Each use (drinking, farming, industry) needs a different quality, and drinking water must be the best.
Recycling example: Nagpur's treated wastewater cools the machines at the Koradi power plant.
About 29% of the world's people lack safe drinking water.
Natural pollution: water picks up minerals and salts from soil and rock; arsenic occurs in parts of Bangladesh and in some regions of India.
Human pollution: sewage, fertiliser and pesticide runoff, and factory chemicals. Polluted groundwater and lake water are hard to clean; flowing rivers aerate themselves.
Powai Lake in Mumbai is polluted, so the city fetches water from over 100 km away.
Drinking water should be 6.5–8.5; groundwater is 6.0–8.5.
The first rains in Pune have a pH of 4–6, so first-flush rainwater should not be used for recharge.
pH: 0–7 is acidic, 7 is neutral, 7–14 is alkaline.
Dissolved oxygen (DO) comes from air and aquatic plants. It is higher in cold, flowing water and near the surface, and fish depend on it.
BOD (Biological Oxygen Demand): 1–2 mg/L is very good, 3–5 mg/L satisfactory, and 6–9 mg/L shows organic pollution.
COD (Chemical Oxygen Demand) is used to check sewage treatment; it should not exceed 250 mg/L.
Indian standards (CPHEEO), desirable values: pH 6.5–8.5, hardness 300 mg/L, chloride 250, fluoride 1.0 (max 1.5), nitrate 45, iron 0.3, TDS 500. Coliforms should be nil.
Singapore imports water from Malaysia, desalinates seawater and purifies sewage into "NEWater" after 47 tests. Each meets about 35% of its need.
Important terms
pH – a measure of acidity or alkalinity on a 0–14 scale.
Dissolved oxygen – oxygen dissolved in water that aquatic life breathes.
BOD – oxygen used by microbes to break down organic matter; a high BOD means pollution.
TDS – total dissolved solids.
Key facts
Parameter
Desirable limit
pH
6.5–8.5
Fluoride
1.0 mg/L (max 1.5)
Nitrate
45 mg/L
TDS
500 mg/L
COD
≤ 250 mg/L
5 important questions
Q1. What is water quality?
The condition of water judged by the amount of dissolved physical, chemical and biological substances; it differs for each use.
Q2. What is pH, and what is the safe range for drinking water?
A 0–14 measure of acidity or alkalinity (7 is neutral); drinking water should be 6.5–8.5.
Q3. Explain BOD.
The oxygen needed by bacteria to break down organic matter. A BOD of 1–2 mg/L is very good; 6–9 mg/L means pollution.
Q4. Why is polluted groundwater dangerous?
It cannot easily be purified once contaminated, and people drinking it directly can be harmed, e.g. by arsenic.
Q5. What is Singapore's NEWater?
City wastewater purified to drinking standard after 47 tests; with desalination, it reduces Singapore's dependence on imported water.
Exam tip
Memorise the pH scale and the BOD ranges; they appear as short-answer and fill-in-the-blank questions.
Water picks up dust, germs, salts and chemicals as it flows and seeps. To keep it safe it must be purified, disinfected and stored properly at home. This chapter covers the purification steps, chlorination with bleaching powder, the OT test, and safe storage habits.
Key points
Sources: running water (rivers, canals, streams), dams, natural ponds and groundwater. Even rainwater collects dust, bacteria, pollen and gases before it reaches the ground.
Remove floating matter.
Coagulation and flocculation with alum, ferric chloride or ferrous sulphate.
Sedimentation.
Softening, if needed.
Filtration.
Disinfection with chlorine.
Storage and distribution.
Purification steps:
Aeration removes CO₂, H₂S, and iron or manganese compounds, and increases dissolved oxygen.
Why disinfect? Clear water can still carry germs that cause typhoid, cholera, jaundice, dysentery, diarrhoea and gastroenteritis.
Bleaching powder (TCL, made by passing chlorine through lime) should have over 33% chlorine. Keep it sealed, dry and closed, or the chlorine escapes and the powder loses strength.
OT (orthotolidine) test: checks for residual chlorine after disinfecting wells and hand pumps. Do it regularly; a positive test means the disinfection worked.
In the monsoon, sources are most easily polluted and epidemics rise, so increase the bleaching powder and test more often.
Clean the vessels daily and keep them covered, raised and out of children's reach.
Use a long-handled ladle and avoid dipping hands in.
Do not keep pots buried in the ground.
Drink without touching the glass to your lips; it keeps the water pure and saves washing water.
Safe storage at home:
Important terms
Coagulation – adding chemicals such as alum so tiny particles clump together.
Chlorination – disinfecting water with chlorine or bleaching powder.
OT test – the orthotolidine test for residual chlorine.
When human activity or natural causes change water so much that it becomes unfit for use, that is water pollution. This chapter covers the sources of pollutants, water-borne diseases, oil spills at sea, the pollution of lakes and wetlands, and the laws and boards that control water pollution.
Key points
Water pollutants: useless solid, liquid or gaseous wastes that mix with natural water and harm living things.
Sludge, and hot water from boilers (thermal pollution).
Sources:
Entamoeba histolytica → dysentery.
Salmonella typhi → typhoid.
Vibrio cholerae → cholera.
Hepatitis viruses → jaundice.
Plasmodium → malaria (spread by Anopheles mosquitoes that breed in water).
Diseases from water-borne microbes:
Oil coats birds' feathers so they cannot fly and drown.
Oysters, crabs and mangroves (whose roots cannot breathe) die.
Examples: MSC Chitra–MV Khalija-III collision near Mumbai (August 2010, about 800 tonnes); near Kamarajar port, Chennai (January 2017, about 60 tonnes).
Oil spills:
Lakes: sewage, oil lamps, idol and nirmalya immersion, and fish feed decay. Oxygen falls, H₂S smells and fish die. Urban encroachment has shrunk or wiped out many lakes.
Wetlands: home to many birds, now harmed by encroachment and sewage. World Wetlands Day is 2 February, first observed in 1997; the Ramsar Convention was signed at Ramsar, Iran.
Model river: the Umngot at Dawki (Meghalaya) is so clean its bed is visible, and polluters are fined.
Law: the Water (Prevention and Control of Pollution) Act, 1974, set up the Central and State Pollution Control Boards.
Functions: plans pollution control, inspects treatment plants, promotes recycling, guides industry and spreads awareness.
Powers: enforces the laws, sets and checks standards, monitors sources.
Maharashtra Pollution Control Board:
Important terms
Water pollution – a change in water quality that makes it unfit for use.
Thermal pollution – heating water bodies with hot industrial discharge.
Oil spill – oil released into the sea by accident.
Wetland – marshy land that is saturated with water and rich in birds.
Key facts
Microbe
Disease
Entamoeba histolytica
Dysentery
Salmonella typhi
Typhoid
Vibrio cholerae
Cholera
Hepatitis virus
Jaundice
5 important questions
Q1. What is water pollution?
A direct or indirect change in the natural quality of water, by humans or other causes, that makes it unusable.
Q2. State four sources of water pollutants.
Household sewage, fertiliser and pesticide runoff, factory chemicals and oil or grease from vehicle washing.
Q3. How do oil spills harm marine life?
Oil sticks to birds' feathers so they drown, smothers oysters and crabs, and coats mangrove roots and leaves so the plants dry up.
Q4. Why are lakes getting polluted and shrinking?
Sewage, religious offerings, oil lamps and decaying fish feed pollute them, and urban encroachment fills them in.
Q5. Name the law and the bodies that control water pollution.
The Water (Prevention and Control of Pollution) Act, 1974, enforced by the Central Pollution Control Board and the State Pollution Control Boards.
Exam tip
Learn the microbe–disease table and the 1974 Act; both appear as match-the-pairs and one-mark questions.