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Ward Planning and Education Secretaries · Chapter 5

Urban Forestry, Water Conservation and Alternative Energy

What to remember

  • Urban forestry means planting and caring for trees and green spaces in and around a town. Trees cool the city, clean the air, reduce runoff and give shade.
  • Water conservation in a town means saving water, harvesting rain, recharging groundwater and reusing treated wastewater. Rainwater volume = rainfall depth x catchment area x runoff coefficient.
  • Alternative (renewable) energy such as solar, biogas and waste-to-energy, together with energy-saving devices like LED lamps, lowers the cost and pollution of urban services.

1. Urban forestry

Cities are hotter than nearby rural land. This is the urban heat island effect: concrete and asphalt store heat and there are fewer trees. Urban forestry reduces this effect and gives many other benefits.

Benefits of urban trees

  • Shade and cooling by shading and by evaporation from leaves.
  • Absorb dust and gases and store carbon.
  • Reduce noise.
  • Slow rain runoff and help water enter the soil.
  • Give homes to birds, insects and bats.
  • Improve health, walking comfort and property value.

Types of urban green space

TypeDescription
Street (avenue) treesTrees planted along roads and medians
Parks and gardensPublic open spaces for rest and play
Urban woodlands / urban forestsLarger groups of native trees inside or beside the city
Green beltA ring of green land around a city that checks sprawl
Institutional greensCampuses, hospital grounds, offices
Roof and vertical gardensPlants on roofs and walls
Riverbank and lake buffersPlants along water bodies that protect the bank

Choosing trees. Pick native, hardy, long-living trees that need little water and have a strong, deep root system. Avoid brittle trees and trees with invasive roots near buildings and pipes. Common avenue trees in India include neem, pongamia (karanj), tamarind, rain tree, peepal and banyan (banyan and peepal need wide space). Use a mix of species so that one pest does not kill them all. Leave enough space between trees and keep clear of overhead wires.

Miyawaki method. A method developed by the Japanese botanist Akira Miyawaki to create a dense small forest using native species planted close together in several layers. It grows fast and is used on small urban plots.

Government efforts. Vana Mahotsav (tree-planting festival) has been held every year in July since 1950. The central "Nagar Van" (urban forest) scheme supports urban forests in towns. Andhra Pradesh has run tree-planting and water-saving drives such as "Vanam-Manam" and "Neeru-Chettu"; check the latest status of such programmes. Municipal bodies plant and look after street trees, and ward-level officials help in site selection and survival checks.

2. Water supply norms

Water demand is planned by litres per capita per day (lpcd). Standard design norms of the Central Public Health and Environmental Engineering Organisation (CPHEEO):

SituationTypical norm
Towns with piped water and sewerage135 lpcd
Towns with piped water but no sewerage70 lpcd
Public stand posts40 lpcd

Worked example 1. A ward has 20,000 persons. Water demand at 135 lpcd = 20,000 x 135 = 27,00,000 litres per day = 2.7 million litres per day (2.7 MLD).

Non-revenue water (NRW) is water produced but not billed because of leaks, theft or poor meters. Reducing leakage is the cheapest way to "find" new water.

3. Water conservation methods

  • Reduce: fix leaks, install meters, use low-flow taps and dual-flush cisterns.
  • Reuse: treat and reuse greywater (from bath and wash) for gardens and flushing; reuse treated sewage from a Sewage Treatment Plant (STP) for gardens, construction and industry.
  • Recycle and recharge: return water to the ground.
  • Protect water bodies: stop encroachment and dumping in tanks, ponds and lakes.
  • Metering and pricing reduce waste.

Rainwater harvesting (RWH) collects rain from roofs and open land and either stores it or recharges the ground.

MethodUse
Roof-top storage tankCollected rain is stored for direct use
Recharge pit / trenchFilters rain into the soil; for small plots
Recharge well / boreSends water to deeper layers; for large roofs
Percolation tankLarge pond that lets water seep into the ground
Check dam / bundSlows streams and raises ground water

A system has a catchment (roof), gutters and pipes, a first-flush device that diverts the dirty first rain, a filter, and a storage or recharge unit.

Formula. Volume of harvestable rain = rainfall depth (m) x catchment area (sq m) x runoff coefficient (C).

Typical C values. Roof about 0.8 to 0.9; paved ground about 0.7 to 0.8; grass or soil lower.

Worked example 2. Roof area 100 sq m, annual rainfall 800 mm = 0.8 m, C = 0.8. Volume = 0.8 x 100 x 0.8 = 64 cubic metres = 64,000 litres (1 cubic metre = 1,000 litres).

National efforts. AMRUT (Atal Mission for Rejuvenation and Urban Transformation, 2015) funds water supply and sewerage in towns. Jal Shakti Abhiyan (begun 2019) and its "Catch the Rain" campaign (from 2021) promote rain harvesting. The Central Ground Water Board studies and regulates ground water use.

4. Alternative (renewable) energy

Renewable sources are replaced by nature and do not run out: sun, wind, water flow, biomass.

SourceHow it worksUrban use
Solar photovoltaic (PV)Panels turn sunlight into electricityRooftop plants, street lights, water pumps
Solar thermalSunlight heats waterSolar water heaters in homes, hostels, hospitals
BiogasAnaerobic digestion of food and organic waste gives methane-rich gasCommunity kitchens, markets, slaughter-house waste
Waste to energyBurning or digesting solid waste to produce power or gasLarge towns with waste plants
WindTurbines turn wind into powerLarger sites, outskirts
Small hydroFlowing water turns turbinesCanal-fall plants

Rooftop solar and net metering. A building with solar panels uses its own power and sends the extra to the grid. The meter records both the units imported and exported, and only the net is paid for. A solar rooftop system of 1 kW needs roughly 10 sq m of shadow-free roof and gives about 4 to 5 units (kWh) in a day. The national rooftop programme "PM Surya Ghar" supports home solar plants. The agency for renewable energy in AP is the New and Renewable Energy Development Corporation of Andhra Pradesh (NREDCAP).

Worked example 3 (solar). A 3 kW system giving 4 units per kW per day produces 3 x 4 = 12 units per day.

5. Energy efficiency

Energy used (kWh) = power (kW) x time (hours).

Worked example 4. A 9 W LED replaces a 60 W bulb used 5 hours a day for 30 days. Saving per day = (60 - 9) W x 5 h = 255 Wh. Saving per month = 255 x 30 = 7,650 Wh = 7.65 kWh.

  • The Energy Conservation Act, 2001 created the Bureau of Energy Efficiency (BEE). BEE gives star labels for appliances; more stars mean lower power use.
  • The Energy Conservation Building Code (ECBC) sets energy norms for large buildings.
  • Energy Efficiency Services Limited (EESL) runs programmes for LED bulbs and street lights.
  • Green building rating systems: GRIHA (national, by TERI and the Ministry of New and Renewable Energy), IGBC (Indian Green Building Council) and LEED (international).
  • Good design: daylight, cross ventilation, shaded windows, light-coloured "cool" roofs.

6. Putting it together in a ward

A ward planner can link the three themes. Keep trees and open land free of concrete so that rain can soak in. Plant trees near recharge pits and lake edges. Ask large buildings to fit rain harvesting, solar water heaters and rooftop solar. Treat and reuse wastewater in parks. Check that every new layout keeps its land for parks and that the trees planted are alive after a year. Small steps repeated across wards lower the water bill, the power bill and the heat of the town.

Exam traps

  • Runoff coefficient is below 1 because some rain is lost.
  • Recharge is for the ground; storage is a tank for use.
  • Greywater comes from bath and wash; blackwater is toilet waste.
  • Net metering counts the difference between import and export.
  • Solar PV makes electricity; solar thermal makes heat.
  • BEE gives star labels; ECBC is a code for buildings.
  • 135 lpcd applies where sewerage exists; 70 lpcd where it does not.
  • Biogas comes from organic waste without oxygen; it is mainly methane.

One-liners

  • 1. Urban heat island means a city is hotter than its surroundings.
  • 2. Miyawaki method creates dense native mini-forests.
  • 3. Vana Mahotsav is celebrated in July.
  • 4. Design norm is 135 lpcd with sewerage.
  • 5. Volume of rain = depth x area x runoff coefficient.
  • 6. 1 cubic metre of water = 1,000 litres.
  • 7. A first-flush device removes the dirty first rain.
  • 8. AMRUT began in 2015.
  • 9. BEE was set up under the Energy Conservation Act, 2001.
  • 10. NREDCAP promotes renewable energy in Andhra Pradesh.
  • 11. Energy (kWh) = kW x hours.
  • 12. STP means Sewage Treatment Plant.

Practice questions

  1. The tendency of cities to be warmer than nearby rural areas is called

    1. urban heat island effect
    2. albedo loss
    3. greenhouse inversion
    4. heat sink basin
    Answer

    A. urban heat island effect

    Concrete and asphalt store heat; trees cool the city.

  2. Which of the following is a benefit of urban trees?

    1. More dust
    2. Shade and lower local temperature
    3. More noise
    4. Higher runoff
    Answer

    B. Shade and lower local temperature

    Trees give shade and cool the air.

  3. A ring of green land around a city that checks urban sprawl is a

    1. slum zone
    2. satellite town
    3. buffer tank
    4. green belt
    Answer

    D. green belt

    Green belts limit sprawl.

  4. The Miyawaki method is used to

    1. grow dense native mini-forests
    2. make biogas
    3. treat sewage
    4. measure rainfall
    Answer

    A. grow dense native mini-forests

    Developed by Akira Miyawaki.

  5. Vana Mahotsav is celebrated every year in the month of

    1. March
    2. July
    3. January
    4. December
    Answer

    B. July

    Vana Mahotsav is the July tree-planting festival.

  6. For towns with piped water and sewerage, the design norm of water supply is

    1. 270 lpcd
    2. 70 lpcd
    3. 135 lpcd
    4. 40 lpcd
    Answer

    C. 135 lpcd

    135 lpcd applies with sewerage.

  7. For public stand posts the water supply norm is about

    1. 135 lpcd
    2. 70 lpcd
    3. 200 lpcd
    4. 40 lpcd
    Answer

    D. 40 lpcd

    40 lpcd for stand posts.

  8. A ward has 10,000 persons and a norm of 135 lpcd. The daily water demand is

    1. 13,50,000 litres
    2. 13,500 litres
    3. 1,35,00,000 litres
    4. 1,35,000 litres
    Answer

    A. 13,50,000 litres

    10,000 x 135 = 13,50,000 litres.

  9. A town of 40,000 persons uses water at 70 lpcd. Daily demand in million litres per day (MLD) is

    1. 28 MLD
    2. 2.8 MLD
    3. 4.0 MLD
    4. 0.28 MLD
    Answer

    B. 2.8 MLD

    40,000 x 70 = 28,00,000 L = 2.8 MLD.

  10. Water that is produced but not billed because of leaks, theft or faulty meters is called

    1. non-revenue water
    2. grey water
    3. hard water
    4. black water
    Answer

    A. non-revenue water

    NRW is a loss to the utility.

  11. Water from bath and wash basins, suitable for treated reuse in gardens, is

    1. blackwater
    2. brine
    3. leachate
    4. greywater
    Answer

    D. greywater

    Greywater excludes toilet waste.

  12. The device that diverts the dirty first rain in a roof-top rain harvesting system is the

    1. float switch
    2. check valve
    3. first-flush device
    4. manometer
    Answer

    C. first-flush device

    It keeps dirt out of the tank.

  13. Volume of harvestable rainwater is calculated as

    1. catchment area / runoff coefficient
    2. rainfall depth / catchment area
    3. rainfall depth + runoff coefficient
    4. rainfall depth x catchment area x runoff coefficient
    Answer

    D. rainfall depth x catchment area x runoff coefficient

    V = P x A x C.

  14. A roof of 100 sq m receives 0.5 m of rain in a year. With runoff coefficient 0.8 the harvestable volume is

    1. 4 cubic metres
    2. 50 cubic metres
    3. 40 cubic metres
    4. 80 cubic metres
    Answer

    C. 40 cubic metres

    0.5 x 100 x 0.8 = 40 cubic metres.

  15. A roof of 200 sq m gets 600 mm of annual rain. With C = 0.9, the volume harvested is about

    1. 120 cubic metres
    2. 108 cubic metres
    3. 10.8 cubic metres
    4. 1,080 cubic metres
    Answer

    B. 108 cubic metres

    0.6 x 200 x 0.9 = 108 cubic metres.

  16. How many litres are there in 64 cubic metres of water?

    1. 64,000
    2. 640
    3. 6,40,000
    4. 6,400
    Answer

    A. 64,000

    1 cubic metre = 1,000 litres.

  17. Which structure is meant to push water into deeper ground layers on large roofs?

    1. Recharge well
    2. Septic tank
    3. Overhead tank
    4. Check valve
    Answer

    A. Recharge well

    Recharge wells feed deeper layers.

  18. A large pond made to let water seep into the ground is a

    1. header tank
    2. percolation tank
    3. oxidation pond
    4. settling tank
    Answer

    B. percolation tank

    Percolation tanks recharge ground water.

  19. AMRUT, a mission for urban water supply and sewerage, was launched in

    1. 1995
    2. 2022
    3. 2005
    4. 2015
    Answer

    D. 2015

    AMRUT was launched in 2015.

  20. The 'Catch the Rain' campaign belongs to the

    1. Swachh Survekshan
    2. Digital India
    3. Jal Shakti Abhiyan
    4. Smart Cities Mission
    Answer

    C. Jal Shakti Abhiyan

    Jal Shakti Abhiyan promotes rain harvesting.

  21. Devices that convert sunlight directly into electricity are

    1. solar photovoltaic panels
    2. solar water heaters
    3. biogas digesters
    4. wind vanes
    Answer

    A. solar photovoltaic panels

    PV means photovoltaic.

  22. A solar water heater uses sunlight to produce

    1. hydrogen
    2. heat
    3. electricity for the grid
    4. methane
    Answer

    B. heat

    It is solar thermal.

  23. Biogas is mainly

    1. nitrogen
    2. oxygen
    3. helium
    4. methane
    Answer

    D. methane

    Anaerobic digestion gives methane-rich gas.

  24. Net metering records

    1. only the water used
    2. the roof area
    3. wind speed
    4. units imported and exported by a consumer
    Answer

    D. units imported and exported by a consumer

    Only net units are charged.

  25. A 5 kW rooftop solar plant gives about 4 units per kW per day. Daily generation is

    1. 4 units
    2. 9 units
    3. 20 units
    4. 45 units
    Answer

    C. 20 units

    5 x 4 = 20 units.

  26. A 60 W bulb running 5 hours a day uses in 10 days

    1. 300 kWh
    2. 0.3 kWh
    3. 3 kWh
    4. 30 kWh
    Answer

    C. 3 kWh

    60 x 5 x 10 = 3,000 Wh = 3 kWh.

  27. A 9 W LED replaces a 60 W bulb used 5 hours daily for 30 days. The saving in energy is

    1. 76.5 kWh
    2. 7.65 kWh
    3. 9.0 kWh
    4. 0.765 kWh
    Answer

    B. 7.65 kWh

    (60 - 9) x 5 x 30 = 7,650 Wh = 7.65 kWh.

  28. The Bureau of Energy Efficiency was set up under the

    1. Energy Conservation Act, 2001
    2. Water Act, 1974
    3. Electricity Act, 1910
    4. Environment Protection Act, 1986
    Answer

    A. Energy Conservation Act, 2001

    BEE was created under the 2001 Act.

  29. Which of the following is a green building rating system?

    1. GRIHA
    2. CPHEEO
    3. AMRUT
    4. ECBC
    Answer

    A. GRIHA

    GRIHA, IGBC and LEED are rating systems.

  30. The Energy Conservation Building Code (ECBC) sets

    1. speed limits on roads
    2. tax rates on land
    3. energy-efficiency norms for large buildings
    4. fire-hydrant sizes
    Answer

    C. energy-efficiency norms for large buildings

    ECBC is a building energy code.

  31. Consider the statements. 1. Urban trees reduce the urban heat island effect. 2. Urban trees increase rainwater runoff. Which is/are correct?

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    A. 1 only

    Trees reduce, not increase, runoff.

  32. Consider the statements. 1. Greywater can be treated and reused for gardens. 2. Greywater is the water from toilets. Which is/are correct?

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    A. 1 only

    Greywater excludes toilet waste, which is blackwater.

  33. Consider the statements. 1. Runoff coefficient is always more than 1. 2. Rain volume = depth x area x runoff coefficient. Which is/are correct?

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    B. 2 only

    C is below 1 because of losses.

  34. Consider the statements. 1. Solar PV produces electricity. 2. Solar thermal systems produce heat. Which is/are correct?

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    C. Both 1 and 2

    Both statements are correct.

  35. Consider the statements. 1. Biogas is made from organic waste without oxygen. 2. Biogas is mainly methane. Which is/are correct?

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    C. Both 1 and 2

    Anaerobic digestion gives methane-rich gas.

  36. Consider the statements. 1. Reducing leakage can save a large amount of water. 2. Non-revenue water is always zero. Which is/are correct?

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    A. 1 only

    NRW exists due to leaks and meter errors.

  37. Consider the statements. 1. The norm of 135 lpcd is for towns with sewerage. 2. The norm of 70 lpcd is for towns without sewerage but with piped water. Which is/are correct?

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    C. Both 1 and 2

    Both are standard design norms.

  38. Consider the statements. 1. BEE gives star labels to appliances. 2. More stars mean higher power use. Which is/are correct?

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    A. 1 only

    More stars mean lower power use.

  39. Consider the statements. 1. Native trees need less water and are hardy. 2. A single species along all roads is the best choice. Which is/are correct?

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    A. 1 only

    A mix of species reduces pest risk.

  40. Match the item with its use. P. Recharge pit Q. Solar PV R. STP 1. Treat sewage 2. Feed ground water 3. Make electricity

    1. P-1, Q-2, R-3
    2. P-2, Q-1, R-3
    3. P-3, Q-1, R-2
    4. P-2, Q-3, R-1
    Answer

    D. P-2, Q-3, R-1

    Pit feeds ground water; PV makes electricity; STP treats sewage.

  41. Match the term with its meaning. P. Green belt Q. Net metering R. First flush 1. Diverts dirty first rain 2. Ring of green land 3. Counts import and export of power

    1. P-1, Q-2, R-3
    2. P-3, Q-1, R-2
    3. P-2, Q-1, R-3
    4. P-2, Q-3, R-1
    Answer

    D. P-2, Q-3, R-1

    Green belt is a ring of green; net metering is import-export; first flush diverts dirty rain.

  42. Match the body with its field. P. NREDCAP Q. CPHEEO R. BEE 1. Water supply norms 2. Energy efficiency 3. Renewable energy in AP

    1. P-2, Q-1, R-3
    2. P-3, Q-1, R-2
    3. P-1, Q-3, R-2
    4. P-3, Q-2, R-1
    Answer

    B. P-3, Q-1, R-2

    NREDCAP: renewable energy; CPHEEO: water norms; BEE: efficiency.

  43. Which of the following is NOT a method of rainwater harvesting?

    1. Percolation tank
    2. Recharge pit
    3. Roof-top storage tank
    4. Burning waste in the open
    Answer

    D. Burning waste in the open

    Open burning is not related to harvesting.

  44. Light-coloured 'cool' roofs help a building mainly by

    1. producing biogas
    2. reflecting sunlight and lowering indoor heat
    3. increasing runoff
    4. storing more heat
    Answer

    B. reflecting sunlight and lowering indoor heat

    Cool roofs reflect heat.

  45. Reusing treated sewage from an STP for gardens and construction is an example of

    1. flood irrigation
    2. water recycling and reuse
    3. groundwater mining
    4. water hardening
    Answer

    B. water recycling and reuse

    Treated wastewater can replace fresh water.

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