Human Impacts - Water Flashcards
Reasons for water demand increases in the last 50 years
- Population increased
- Use of water in agriculture increased
- Industrial and social development increased
- Decreasing rainfall in some areas
Renewable resource
- A natural resource which can replenish with the passage of time
- Through biological reproduction or naturally recurring processes (e.g. Cycles)
A problem with water availability has to do with unequal supply and demand in an area. Explain?
- Population density varies.
- E.g. Settlement in cities equal areas of very high demand, often with low supply.
A short term solution to the limited supply of water?
Water rationing
Constructions designed store large amounts of water to meet a varied demand in a particular area
Dams
Disadvantages of dam construction
- 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
Advantages of dam construction
- Immediate access to water
- Easier for council to budget water use
- Hydroelectric potential
- Other economic benefits include engineering, construction and investment possibilities
Wetlands are?
- Found in and around river systems
- Where flow of water slows down as it reaches the ocean
Examples of wetlands
- Vleis
- Springs
- estuaries
- floodplains
- bogs
- swamps
- lakes
- marshes
Vegetation characterizing wetlands
- Reeds
- Sedges
Animals characterizing wetlands
- Water birds
- Aquatic insects
- Small fish
Wetland ecosystem services
- Store water
- Control flooding
- Reduce sediment load in rivers
- Maintain river flow
- Improve water quality
- Provide habitat for wildlife
Causes of wetland destruction
- Lowered water table (by overuse)
- Drainage of wetlands (for other land use)
- Pollution
- Overexploitation of wildlife (e.g. fishing)
Working for Wetlands program
- Government initiative for Monitoring
- Reclaiming
- Managing
Farming practices that affect water availability
- Wasting water (e.g. sprinklers with lots of evaporation)
- Farming too close to river systems (soil erosion)
Exotic species
Species not naturally occurring in a particular area or region
Planting only one type of plant in agriculture of forestry
Monoculture
Effect of exotic species on water availability?
- These trees consume more water than indigenous species
- Indigenous species deprived of water
Examples of exotic plantation trees?
- Eucalyptus
- Pines
- Wattles
Other problems caused by some exotic species
- Spread very fast
- Grow faster than indigenous species, outcompeting
- Transform the habitats of indigenous species
- Change fire intensity and frequency
An underground layer of water-bearing permeable rock or sediment from which ground water can be extracted
Aquifer
Depletion of aquifers is caused by
Over-pumping using:
- Boreholes
- Well-points
Consequences of the over-pumping of aquifers
- Water supply for rural areas depleted
- Sink holes
- Increased salinity of underground water in coastal areas
South Africa’s policy of free water and the cost of water
- 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.
