Soil + Water and Change
Soil
Water
Soil degradation: process of soil losing its fertility and nutrients, the quality of the soil reduces and eventually becomes biologically dead
Wind and water: rain can wash away topsoil and wind can blow it away causing degradation
Biological: loss of humus or plant/animal life
Physical: loss of soil structure or change in permeability
Chemical: change in chemical composition of the soil - acidification, salnisation, chemical pollution or loss of nutrients
Importance of soil:
Humus: fertile layer of soil usually found near the top - made up of biological matter
Soil fertility is important to successful food production and maintaining life - plants, animals etc.
Soil degradation causes
Human causes
Physical causes
Rising temperatures
Decreased rainfall
Flash floods
Topography
Overgrazing
Overcultivation
Deforestation
Industrial pollution - chemicals leaching into soil
Unsustainable water use - area eventually becomes arid
Problems and solutions: soil degradation
Problems
Solutions
desertification
dust storms
top soil erosion
reduced crop yields
famine
conflict
crop rotations and fallow periods
terracing and contour ploughing
reforestation
grazing quotas
Scarcity
Physical water scarcity: demand for water is greater than supply - doesn't need to be arid areas as demand might not be large
Economic water scarcity: when there is water available but for some economic reason it is not possible to fully utilise the source of water - e.g. extraction, transport or treatment costs could be too high
Distribution of water resources
Only around 2.5% of the world's water is fresh - of this most is underground or in the form of ice (frozen)
Areas with smallest water supply: North Africa, Southern Africa, Middle East, South Asia, East Europe
Areas with no water shortages: most of N hemisphere - Europe, N America and Russia
Areas with physical water scarcity: N Africa (Sahara), Middle East, Pakistan, Afghanistan, Iran, Northern India and Northern China (Gobi desert)
Areas with economic water scarcity: Central and S America, SE Asia and Australia
Water Poverty Index (WPI) looks at 5 variables to assess a country's water poverty
Resources - amount of ground and surface water available / person in the country or region
Access - looks at time and distance involved in obtaining the water e.g. does everyone have taps, or do they walk to a well?
Capacity - how the community manages and uses the water
Use - how is it used? industry, agriculture or domestic use?
Environment - assesses sustainability of use e.g. are rivers and aquifers being extracted from sustainably or is too much being taken
Europe, Americas, AUS - high scores on WPI African, South Asian and Middle eastern countries score badly
Water shortages
Causes
Physical scarcity
Economic scarcity
Population growth
Pollution
Domestic demands
Agricultural demand
Industrial demand
Sewage
Climate change
Political? e.g. a river that flows in 2 countries
Groundwater depletion
Problems
Crop failure
Drought
Livestock deaths
Famine
Salt water intrusion - linked to ground water depletion
Conflict
Refugees
Disease
Biodiversity loss
Solutions for water stress
Sewage treatment : requires physical, chemical and biological processes to make water clean and drinkable: only Singapore does this on a large scale
Virtual water
Desalination - evaporate water or reverse osmosis - energy intensive and expensive
Education on basic conservation methods e.g. shower instead of bath or half flush toilets
Water charities e.g. wateraid building wells
Irrigation projects e.g. In Libya
Reduce leakage
Water metering