4.a human factors on water

• deforestation
• urbanisation 
• mining 
• dam building 
• farming

• trees store of water 
• when trees are removed water store removed
• less evapotranspiration 
• less precipitation 
• drought 
• more deforestation due to dying trees/combustion 
• positive feedback loop 

• increased run-off
• increased discharge into rivers and lakes 
• shorter lag time 
• peak discharge increase
• flooding 

OR

• reduced precipitation due to reduced evapotranspiration 
• drought 
• drying up of rivers and lakes

• reduced soil moisture storage 
• less organic matter decomposing 
• increase absorbtion of solar energy  and higher temperatures 
• drought 
• reduced humidity, cloud formation and precipitation- drier soils

urbanisation- movement of the population from rural countryside to urban. Leading to an increase in the number of houses built in the city and roads for accessibility 

• The BR-319 (Manaus-Porto Velho) Highway
  •  built in the early 1970s by Brazil’s military dictatorship
  •  abandoned in 1988
  • The highway route is essentially a lawless area today, and the lack of governance is a critical issue in the battle over licensing the highway reconstruction project.
• deforestation 
• raising risks of flooding or drought- extremes 
• decades of logging, land clearing and deforestation has caused record breaking droughts in:
  • 2005
  • 2010
  • 2015/16

• surface store- rivers etc
  • store can be increased downstream as water used fto extract ores and minerals washes into the river channels through run-off
• vegetation store 
  • mining doesn't directly impact vegetation 
  • deforestation that occurs to mine
  • reduction of tree store
• groundwater store
  • decrease in percolation 
• soil store
  • top soil destroyed- most nutrition and where shallow roots get water from
  • vital store depleated 
  • most water stored on surface 

• hydraulic mining- blasting soil surface with high powered hoses to seperate minerals and metals from soils

Carajas mining 

• E.g the Carajas mine (largest iron ore in world) uses hydraulic mining 
• main pits had produced 1.2 billion tons of high-grade iron ore
• Brazil 

• mineral production has increasing value to the Brazil’s economy.

• The acid runoff further dissolves heavy metals such as copper, lead, mercury into groundwater or surface water. 
• completely destroys natural daily water cycle in area
• pollutes fresh water stores
• mercury can seep into drinking water supplies 
• disrupted growth and reproduction of aquatic plants and animals 

dam- man made structure whereby the main purpose is to restrict the flow of water.

• creates large surface store (new water body-resevoir) in a previously forested area
• decreased river flow downstream 
• vegetation store depleated
• evaporation increase- precipitation increase

• cattle ranching largest cause of deforestation 
  • accounts for 80% of deforestation rates 
• deforestation means less trees
  • less interception
  • less uptake of water
  • less throughfall
  • transpiration decrease 
  • percolation not greatly affected as rocl composition wont change
  • surface waters not greatly affected