Lecture 2: The changing water environment 2

Question 1

Climate variability and change

Answer 1

● Warmer world=more evapotranspiration
● More evapotranspiration=more cloud cover=more rainfall
● Spatial distribution will change
● Temporal (seasonal) distribution will change
● Some stores e.g. snow and ice will be lost
● Change to intensity (extremes)

Question 2

Ecosystems services and their maintenance

Answer 2

● Water based ecosystem services (ES) ○ quantity
○ quality
○ regulation
● Human impacts on ES and implications for water based
ecosystem services

Question 3

Two flows of ES

Answer 3

● ES generated at a point, flow along gradients
● Land rivers : Water quantity, dilution (quality), sediment (nutrients),
regulation (timing)
● Sky rivers : Rainfall (generation), cloud cover (reduced ET)

Question 4

Deforestation on climate

Answer 4

Since land surface characteristics control the surface albedo (reflectivity) to short wave (solar) radiation as well as the aerodynamic roughness of the surface, changes in land cover can bring about large scale changes in regional climate.

Question 5

Forest hydrology and land use change

Answer 5

Forest conversion to pasture generally leads to increases in seasonal and annual total streamflow because forests :
– have a higher surface area than grassland

– are aerodynamically rougher than grassland

– have an extensive leaf and root network and thus make more water available for evapo- transpiration than grassland

– encourage infiltration and local storage/slow seepage over runoff and stormflow because of higher infiltration capacity and increased soil and surface water storage capacities