Water Resources

Question 1

Embodied Water

Answer 1

o Amount of water actually used to produce an item (life cycle assessment)

Question 2

Hydrologic Cycle

Answer 2

o	Precipitation
o	Evaporation
o	Surface storage
•	Streams, rivers, lakes, snow, glaciers, oceans
o	Polar ice and glaciers
o	Soil storage (moisture)
o	Underground storage (groundwater)
o	Biosphere (plants, animals, microorganisms)

Question 3

Hydrosphere: Volumes and residence times

Answer 3

o	Less than 2% of water is easily accessible and less than 1% is fresh & accessible
o	Water is renewable and able to sustain life and development (if we don’t pollute or overuse it)
o	Mean residence times:
•	Groundwater: 1400 years
•	Lakes: 17 years
•	Soil moisture: 1 year
•	Streams: 16 days
•	Atmosphere: 8 days
•	Biosphere: several hours

Question 4

Global Water Resource Use

Answer 4

o Agriculture: main use

• 70% of freshwater use

Question 5

Basic Water Requirements

Answer 5

o Drinking water: 5L/person/day
o Sanitation: 20L/person/day
o Bathing: 15L/person/day
o Food preparation: 10L/person/day

Question 6

Water Stress

Answer 6

o Occasional/local problems: >1700 m3/year per capita
o Water stressed: 1000-1700 m3/year per capita
o Water scarcity: < 1000 m3/year per capita

Question 7

Water Stress Index

Answer 7

WSI=(D+1+A)/Q
D = domestic water demand (mean annual value)
I = industrial water demand (mean annual value)
A = agricultural water demand (mean annual value)
Q = sustainable water supply (mean annual value)
Stress levels:
> 0.4: severe water limitation
0.2-0.4: medium-high stress
<0.2: low water stress

Question 8

Industrial Water Use

Answer 8

o Power generation: hydro-electric power stations, cooling water
o Food processing: washing, base or additive
o Chemical production: solvent/solution base, carrier medium

Question 9

Energy and Water Links

Answer 9

o Water for energy: energy power and production requires water for cooling etc.
o Energy for water: water collection, processing and distribution requires power