2 Clean Water and Salination / groundwater ILOs

(6) Clean and sanitary water

Describe global water distribution and its implications 

majority of Earth’s water is undrinkable (saline)

Majority of freshwater (69%) is stored in glacies

• not accessible

Drinkable water

• found in aquifers mainly in arid conditions

Explain the hydrological cycle with an emphasis on groundwater

movement of water through processes such as:

• evaporation

• condensation

• transpiration

• rainfall

to recharge ground water supply

Define porosity

void space in rock which can be infilled with fluid

Define permeability

waters ability to pass through porous space

not always directly correlated to porosity

Define aquifers

permeable rock under Earth’s surface which can hold or transmit water

What is the significance of porosity, permeability and aquifers on water supply

aquifers hold a lot of the groundwater which we extract

porosity and permeability control how easily recharge can happen

Discuss groundwater abstraction and recharge  

abstraction

• taking away groundwater for drinking water

recharge

• groundwater entering back into the area which has been abstracted from

abstraction =/= discharge

especially as a lot of aquifers are located in arid (hot and dry) regions

Explain the concepts of water scarcity

people being unable to access safe drinking water mainly affected urban areas which has expanded exponentially with global urban population growth

0.8B people → 1950

4.4B → 2020

6.7B → 2050 predicted

Explain the concepts of virtual water

groundwater used for agriculture (70%) and for industrial product making (30%)

it accounts for 11% of groundwater abstraction usage and is becoming increasingly unsustainable

Explain the concepts of water quality

assessed based on geochemical (organics, metalls, pH, etc) and biological (species diversity) factors

3 in 10 do not have access to safe water globally

millions in S/SE Asia drinking arsenic contaminated water

Identify technological and management approaches to addressing water scarcity 

Desalination through reverse osmosis

• pass water through permeable membrane leaving a hypersaline concentrate (brine)

• expensive

Reserviour construction

• large infrastructure investments which can be a burden especially on Indian and Chinese goverments

• negative ecological impacts

Further groundwater exploitation

• increases likelihood of desalination processes

• recharge is not happpening at rates we would like

Interbasin water transfer

Domestic virtual water table