Evapotranspiration

Question 1

What is evaporation

Answer 1

liquid water is converted to water vapour (vaporisation) and removed from the evaporating surface (vapour removal)

Question 2

What is transpiration

Answer 2

vapourisation of liquid water contained in plant tissues and vapour removal to the atmosphere

Question 3

What is Evapotranspiration

Answer 3

evapotranspiration is the combination of evaporation and
plant transpiration.

Question 4

ET drivers

Answer 4

• Heating by Solar radiation
• Geothermal
• Re-radiation

Question 5

Total ET over large areas

Answer 5

1. Calculate relevant ET measure for different vegetation types,
   open water bodies, climatic conditions.
2. Use interpolation or averaging method to calculate area weighted total ET.
3. ET loss part of the bookkeeping for catchment scale models.

Question 6

Why model Evapotranspiration?

Answer 6

1. Understand and predict soil
   moisture. This in turn determines
   flood severity, groundwater
   recharge, vulnerability to drought,
   and crop stress.
2. Part of the water budget, so
   important for allocation decisions:
   e.g., drinking vs. hydropower vs.
   irrigation