Chapter 4: Water and its Management

Question 1

describe the distribution of water on earth

use percentages

Answer 1

97% - saline (oceans)
3% - fresh water => 68.7% glaciers + 30.1% groundwater + 0.9% other + 0.3% surface water => 87% lakes + 11% swamps + 2% rivers
- majorly found in Brazil, Russia, Canada, Indonesia, China, Colombia

Question 2

Describe the stages of the water cycle

Answer 2

Evaporation => condensation => precipitation (rain or snow or hail) => interception(trees+plants taking water before it reaches ground) + inflitration(water seeps through ground) + through flow(infiltrated water flows through ground) + groundwater flow(infiltrated water through rocks) + surface run off => transpiration + evaporation

Question 3

Briefly describe why humans need water? (Describe 3 purposes)

Answer 3

DOMESTIC
- drinking + cooking - 3%
- in medc, 50% used to flush toilet 20% to wash clothes - less used in ledc
INDUSTRIAL
- cooling in production of electricity
- universal solvent
Washing, dyeing, etc
AGRICULTURAL
- irritations, husbandry
- photosynthesis

Question 4

What is an aquifer?

Answer 4

A store of water in porous rocks such as limestone or sandstone underground

Question 5

How is freshwater obtained from rivers?

Answer 5

• simple rural way, dipping bucket into water
• reservoir (artificial lake) near dam or bank side
• service reservoir - treated potable water is stored
• water tower - potable water stored for immediate use
• cistern
• dam

Question 6

How can freshwater be extracted from the ground?

Answer 6

• Wells- traditional + rural
• could be an artisan aquifer ‘ water in understanding pressure - will rise up by itself

Question 7

Describe the methods through which water can be obtained from the sea

Answer 7

Methods of desalination
DISTILLATION
- water is boiled and released as vapour
- vapour condensed as water to use
- 10-30% efficient
- produces large quantities of waste+brine(salt water)
- energy needed for process - can cause pollution
- usually found in energy rich countries aka Middle East
REVERSE OSMOSIS
- 30-50% efficient
- requires less energy than distillation
- pumps force seawater through pipes (this uses energy)
- seawater is pumped under very high pressure through thousands of fine membranes to remove salt (also uses energy)
- clean water is producedv

Question 8

Factors affecting safe drinking water around world

Answer 8

Water wealth depends on
- rain and precipitation
- Population ratio to water availability
- availability of potable water
- Economic wealth
Sanitation systems
- water treatment processes
Difference within country - rural urban urban usually get it - more Wealth- can put more pressure on authorities - cheaper to install in urban where people are not scattered but live close together

Question 9

What is the difference between physical and economic water scarcity?

Answer 9

PHYSICAL - may be because of low rainfall - high evaporation - natural factors
ECONOMIC - may have water but cannot extract it - cannot make it available

Question 10

What are the advantages and disadvantages of dams?

Answer 10

ADV
- generation of electricity in HEP
- flood control
- irrigation
- tourism and leisure
- provision of water
- creation of habitat for wetland species
- access by boat to otherwise inaccessible areas
DISADV
- mass relocation of people
- flooding land
- disrupts life cycle of fish and aquatic people
- alters water supply for downstream people
- reduces natural flooding of minerals in soil
- can have siltation

Question 11

If I want to build a dam, what factors should I consider?

Answer 11

• it has to be made on a river valley and the valley should be narrow (for Economic reasons)
• also needs to be in a high up valley - the higher the dam the better the pressure
• should be away from Developed areas to reduce risk of pollution
• should consider the wildlife affected and the local people as well

Question 12

Are dams sustainable?

Answer 12

• can have problems in the long term
• reservoir can become silted
• if dam structure is under a lot of pressure, can deteriorate and eventually fail
• minerals na acids can cause stricture to dissolve
• can have negative effects on surrounding areas and wildlife
• however dams are sustainable compared to fossil fuels

Question 13

How do water related diseases spread?

Answer 13

Bacteria may enter drinking water from sewage, if sanitation is poor. If these bacteria are pathogens, and the water in which they live in is drunk untreated, diseases can be spread
Pathogen - bacteria and virus that can cause disease

Question 14

Compare cholera and typhoid. Including the bacterium type, symptoms, treatment etc

Answer 14

TYPHOID
Infective Bacterium - Salmonella typhi or salmonella paratyphi
Time for symptoms to hit - 6-30 days
Symptoms - fever + abdominal pain with skin rash + diarrhoea + vomiting
Consequence - 3-5% people don’t get symptoms - fatal if not treated
Treatment - antibiotics + vaccine
CHOLERA
Infective bacterium - vibrio cholerae
Time for symptoms to come - hours to 5 days
Symptoms - diarrhoea + vomiting
Consequences - mild but lead to dehydration and death
Treatment - rehydration + vaccine

Question 15

How does malaria develop?

Answer 15

• Malaria is water related because organism that spreads it requires malaria to breed
• mosquito lays it’s eggs in still water where larvae develop
• malaria caused by plasmodium
• mosquito acts as vector
• First the mosquito ingests the disease via bite from human
• then the plasmodium multiplies inside the mosquito
• mosquito transmits plasmodium to human via bite
• inside human, plasmodium enters liver cells and multiplies by cell division
• lover cells burst, plasmodium is released into human blood and the cycle continues

Question 16

How can I protect myself from malaria?

Answer 16

• avoid being outside b/w dusk and Dawn in countries where malaria mosquitoes are active - the species of anopheles mosquito that transmits malaria only flies at night
• wear clothing that covers most of the body and use mosquito repellant
• sleep under mosquito net sprayed with insecticide

Question 17

How can the Government prevent Malaria?

Answer 17

Strategies based on controllnig the vector
- spraying insecticide inside buildings/houses
- draining wetland area to eradicate breeding sites
- introducing predator fish for larvae and pupae of mosquito
- pouring oil onto water surface to stop larvae from breathing and adults from laying eggs
- possibility malaria is favoured by Global Warming

Question 18

What is Biological Oxygen Demand?

Answer 18

it is the amount of oxygen something would use up if released directly into a river or lake for example sewage has a BOD

Question 19

Describe the steps of Sewage Treatment

pg 100

Answer 19

1. Sewage Outfall - waste water from homes + industry is taken to sewage treatment works through teh sewers
2. Screening Tank - large objeacts removed from waste using coarse grid
3. Primary Treatment - in first settlnig tank slid organic matter (mainly human waste) is allowed to settle to the bottom of the tank - this settled material called sludge (treated in no 7) - cleaned water overflows to sides of tank to next stage
4. Secondary Treatment, oxidation - water is pumped into a tank where O2 is bubbled through it - encourages growth of bacteria+other microbes which break down dissolved organic matter that causes BOD
5. Secondary Treatment, second setting tank - water enters second settlnig tank where bacteria settles to bottom forming sludge - cleaner water overflows further as effluent
6. effluent is discharged to environment
7. sludge digester - oxygen free conditions are created to encourage growth of bacteria to break done sludge - releasing methane which can be burnt
8. treated sludge can be dried in sludge lagoons and used as organic fertiliser on farmland
9. tertiary treatment (optional) - further filtering of effluent or chlorination

Question 20

Describe ways to achieve improved sanitation facilities (domestic)

Answer 20

1. Flush Toilet - uses holding tank for flushing water+water seal to prevent smells
   - pour flush toilet has a water seal but uses water poured by hand for flushing - water can be removed by: connection to a system of sewer pipes aka sewerage that collects
2. Pit latrine - platyform is a dry pit fully covered by a platform - platform covers the pit without exposing contents other than through hole - sometimes ventilated to take away smells
3. Composting toilet - dry toilet in which vegetable waste, straw, grass, sawdust, and ash are added to human waste to produce compost

Question 21

Describe coagulation water treatment

Answer 21

• Water that is fit for human use is called potable water
• to be potable it undergoes coagulation treatment
• coagulanmts make particles in water stick together and settle to the bottom of the container
• water is then filtered through sand
• to kill disease cusing organisms aka pathogens chlorine is added to the water - chlorination

Question 22

Provide the impacts of industrial pollution in water

Answer 22

• biomagnification - most common example - heavy metals such as lead, mercury, cadmium are toxic and can be stored in the bodies of plants and animals including humans - can build up to highl evels and cause illness
• acid rain - water becomes very acidic - fish and plants die - dieback occurs - when this water evaporates it comes back down as acid rain - rain usually has pH of b/w 5 and 6 - acid rain has lower pH - values as low as 2 are recorded

Question 23

Acid Rain (What can cause+impacts on aquatic systems+how to reduce)

Answer 23

CAUSES
- when fossil fuels such as coal+oil are burned gases such as sulfer dioxide (SO2) and oxides of nitrogen are produced - gases enter atmosphere and can be blown long distances - react with water to form acids - SO2 dissolves in water in clouds producing sulfuric acid and oxides of nitrogen create nitric acid - gases can blow from country to country
- water in lakes also acidic - ripple effect
IMPACT on Aqua Life
- lowe pH makes water inhabitable for organisms
- fish egg laying reduced->young fish malformed
- can cause leaching of heavy metals such as aluminium, lead and mercury from soil to water - aluminium clogs fish gills
- some minerals essential for life such as calcium and potassium are washed out of lake and river
- reduces algal growth
- effects whole ecosystem
REDUCTION
- renewable energy
- use low sulfur varieties of fossil fuels
- remove sulfur in emissions using scrubbers
- reduce oxides of nitrogen emissions by burning with cooler flame or adjusting air to fuel ratio
- clean air acts

Question 24

Define Dieback

Answer 24

Dieback os the death of a tree or shrub that startes at the tip of its leaves or roots and spreads towards the centre of the plant, caused by unfavourable environmental conditions or disease

Question 25

What is leaching?

Answer 25

leaching is the movement of a soluble chemical or mineral away from soil caused by the action of rainwater

Question 26

What are some of the sources of excess organic matter and minerals in water?

Answer 26

• nitrogen compounds produced by cars and factories
• discharge of setergents and untreated sewage (nitrates and phosphates)
• discharge of treated sewage
• dissolving of nitrogen oxides - from internal combustion engines and furnaces
• run off from streets (nitrates+phosphates)
• manure run off (nitrates+phosphates+ammonia)
• inorganic fertiliser run off(nitrates+phosphates)
• natural run off

Question 27

Describe Eutrophication

Answer 27

nutrients enter water (nitrates+phosphates) -> stimulate high algal growth and algal bloom -> algae die rapidly -> increase in organic matter in water -> bacteria decompose dead algae increasing organic matter -> organic matter from sewage, manure, paper waste, and other sources also enters -> bacteria uses up oxygen and level is lowered -> fish and other aquatic animals inclujding insect larvae die

Question 28

Describe effects of pesticide and herbicide pollution

Answer 28

• pesticides are meant to kill - are very harmful to humans as well
• pesticides are generally water soluble so water pollution by these arochemicals is a major concern
• insecticides will kill both insects and other organisms