Human Impacts - Water

Question 1

Reasons for water demand increases in the last 50 years

Answer 1

• Population increased
• Use of water in agriculture increased
• Industrial and social development increased
• Decreasing rainfall in some areas

Question 2

A problem with water availability has to do with unequal supply and demand in an area. Explain?

Answer 2

• Population density varies.
• E.g. Settlement in cities equal areas of very high demand, often with low supply.

Question 3

A short term solution to the limited supply of water?

Answer 3

Water rationing

Question 4

Constructions designed store large amounts of water to meet a varied demand in a particular area

Answer 4

Dams

Question 5

Disadvantages of dam construction

Answer 5

• Rivers dry up
• Natural flow rates changes
• Vegetation changed along banks of rivers
• Ecosystems disrupted
• Soil erosion
• Rivers and dams fill with silt
• Loss of water through evaporation from dam

Question 6

Advantages of dam construction

Answer 6

• Immediate access to water
• Easier for council to budget water use
• Hydroelectric potential
• Other economic benefits include engineering, construction and investment possibilities

Question 7

Wetlands are?

Answer 7

• Found in and around river systems
• Where flow of water slows down as it reaches the ocean

Question 8

Examples of wetlands

Answer 8

• Vleis
• Springs
• estuaries
• floodplains
• bogs
• swamps
• lakes
• marshes

Question 9

Vegetation characterizing wetlands

Answer 9

• Reeds
• Sedges

Question 10

Animals characterizing wetlands

Answer 10

• Water birds
• Aquatic insects
• Small fish

Question 11

Wetland ecosystem services

Answer 11

• Store water
• Control flooding
• Reduce sediment load in rivers
• Maintain river flow
• Improve water quality
• Provide habitat for wildlife

Question 12

Causes of wetland destruction

Answer 12

• Lowered water table (by overuse)
• Drainage of wetlands (for other land use)
• Pollution
• Overexploitation of wildlife (e.g. fishing)

Question 13

Working for Wetlands program

Answer 13

• Government initiative for Monitoring
• Reclaiming
• Managing

Question 14

Farming practices that affect water availability

Answer 14

• Wasting water (e.g. sprinklers with lots of evaporation)
• Farming too close to river systems (soil erosion)

Question 15

Exotic species

Answer 15

Species not naturally occurring in a particular area or region

Question 16

Planting only one type of plant in agriculture of forestry

Answer 16

Monoculture

Question 17

Effect of exotic species on water availability?

Answer 17

• These trees consume more water than indigenous species
• Indigenous species deprived of water

Question 18

Examples of exotic plantation trees?

Answer 18

• Eucalyptus
• Pines
• Wattles

Question 19

Other problems caused by some exotic species

Answer 19

• Spread very fast
• Grow faster than indigenous species, outcompeting
• Transform the habitats of indigenous species
• Change fire intensity and frequency

Question 20

An underground layer of water-bearing permeable rock or sediment from which ground water can be extracted

Answer 20

Aquifer

Question 21

Depletion of aquifers is caused by

Answer 21

Over-pumping using:

• Boreholes
• Well-points

Question 22

Consequences of the over-pumping of aquifers

Answer 22

• Water supply for rural areas depleted
• Sink holes
• Increased salinity of underground water in coastal areas

Question 23

South Africa’s policy of free water and the cost of water

Answer 23

• Every household may receive first six kilolitres of water used each month free.
• Water is thus charged on a sliding scale.
• More used, the greater the cost per kilolitre each month.

Question 24

List at least 5 domestic water pollutants

Answer 24

• Detergents
• Cleaning agents
• Toiletries
• Garden sprays (e.g. Pesticides)
• Cooking oils
• Grey water (basins and baths)
• Black water (sewage)

Question 25

List at least 5 industrial water pollutants

Answer 25

• Heavy metal compounds
• Metal compounds
• Salts
• Sulphates
• Chlorides
• Acids
• Oil byproducts
• Carcinogens
• Petrochemicals
• Thermal pollution (hot waste water)

Question 26

Environmentally friendly cleaning liquid recipe

Answer 26

• 1 cup bicarbonate of soda
• 1/2 cup of vinegar
• 2 teaspoons of salt
• 2 table spoons of lemon juice

Question 27

List at least 3 agricultural water pollutants

Answer 27

• Fertilizers
• Pesticides
• Herbicides
• Manure waste and other organic wastes

Question 28

List at least 3 mining water pollutants

Answer 28

• Arsenic
• Metals e.g. chromium
• Sulphates
• petrochemicals
• Various acids

Question 29

List at least 3 water borne diseases sometimes caused by untreated sewage affecting drinking water

Answer 29

• Escherichia coli (E. coli)
• Cholera
• Hepatitis A
• Dysentery
• Gastroenteritis T
• yphoid fever

Question 30

Algal blooms and depleted oxygen levels caused by excess nutrient runoff into waterbodies

Answer 30

Eutrophication

Question 31

Process of eutrophication

Answer 31

• Excess nutrients enter water
• Algae and weeds grow
• Increased decomposers
• Bacteria use up all oxygen in water
• Fish and other animals die
• Increased anaerobic bacteria decomposers
• Harmful toxins released by anaerobic bacteria

Question 32

Hot waste water released into waterways

Answer 32

Thermal pollution

Question 33

Places where large amounts of water cleaned for domestic use

Answer 33

Water purification plants

Question 34

Effects exotic aquatics plants have on water systems

Answer 34

• Eutrophication
• Shut out sunlight for indigenous aquatic plants
• Clog up waterways disrupting flow
• Block irrigation pipes and canals

Question 35

Introduction of natural pest species to attack invasive exotic species

Answer 35

Bio-control

Question 36

Examples of harmful exotic aquatics

Answer 36

• Water hyacinth
• Kariba weed
• Water lettuce
• Parrots feather

Question 37

Use of indigenous organisms as indicators of the quality of certain ecosystems

Answer 37

Bio-monitoring

Question 39

Renewable resource

Answer 39

• A natural resource which can replenish with the passage of time
• Through biological reproduction or naturally recurring processes (e.g. Cycles)