CHAPTER 5

Question 1

It is the water returned to the air from a liquid to a gaseous state.

Answer 1

Evaporation

Question 2

It is the evaporation from plants.

Answer 2

Transpiration

Question 3

It is the combined evaporation and transpiration.

Answer 3

Evapotranspiration

Question 4

Used interchangeably with evapotranspiration but technically, it refers to the sum of ET and water used by the plants for tissue building processes.

Answer 4

Consumptive Use

Question 5

Give the 3 importance

Answer 5

• for water conservation
• for determining irrigation requirements for crops.
• for determining water storage in reservoir

Question 6

What are the factors affecting evaporation?

Answer 6

• Meteorological Factors
• Nature of the evaporating surface
• Effects of water quality

Question 7

TRUE OR FALSE:

Evaporation is directly proportional to air temperature.

Answer 7

True

Question 8

TRUE OR FALSE:

Solar Radiation affects the degree of air saturation.

Answer 8

False

ans: Vapor Pressure

Question 9

TRUE OR FALSE:

Vapor pressure directly affects temperature.

Answer 9

False

ans: Solar radiation

Question 10

TRUE OR FALSE:

Solar radiation is fast in dry air.

Answer 10

False

ans: Evaporation

Question 11

TRUE OR FALSE:

Evaporation is directly proportional to wind speed.

Answer 11

True

Question 12

TRUE OR FALSE:

All surface exposed to precipitation are potentially evaporating surfaces.

Answer 12

True

Question 13

TRUE OR FALSE:

The smaller the area exposed to evaporation, the faster the rate of evaporation.

Answer 13

False

ans: The LARGER the area exposed to evaporation, the faster the rate of evaporation.

Question 14

TRUE OR FALSE:

Evaporation varies inversely with salinity of water.

Answer 14

True

Question 15

TRUE OR FALSE:

Evaporation rate is slower in fresh water due to high vapor pressure.

Answer 15

False

ans: Evaporation rate is FASTER in fresh water due to high vapor pressure.

Question 16

TRUE OR FALSE:

For saturated soil, evaporation may be similar to that from an open free-water surface. As soil moisture decreases, the rate of evaporation also decreases.

Answer 16

True

Question 17

_________ help in moisture conservation because they decrease the rate of evaporation.

Answer 17

Mulches

Question 18

Give the 2 measurement of evaporation:

Answer 18

• Evaporation Pans
• Tank and Lysimeter Studies(?)

Question 19

It is also called as evapotranspirimeters.

Answer 19

Lysimeter

Question 20

Give the 4 measurement of evapotranspiration:

Answer 20

• Field experimental plots
• Soil water studies
• Integration methods
• Inflow-outflow method

Question 21

It is the quantity of water applied in these plots is kept in small to avoid deep percolation losses and surface runoff is measured.

Answer 21

Field experimental plots

Question 22

The samples are taken at various depths in the root zone.

Answer 22

Soil water studies

Question 23

Defined as the water used by plants and evaporation from the water and soil surfaces are combined for the entire area involved.

Answer 23

Integration Methods

Question 24

It is the inflow into the area (precipitation), outflow from the area and change in groundwater level are evaluated.

Answer 24

Inflow-outflow method

Question 25

Give the 3 categories of methods of predicting evaporation and ET:

Answer 25

- Mass Transfer - Energy Balance - Empirical Methods

Question 26

Water moves away from evaporating and transpiring surfaces in response to the combined phenomena of turbulent mixing of the are and the vapor pressure gradient.

Answer 26

Mass Transfer

Question 27

It required measurements of wind and humidity at two or more elevations.

Answer 27

Mass Transfer

Question 28

Heat is required for evaporation of water, so if there is no change in water temperature, the net radiation or heat supplied isa measure of evaporation.

Answer 28

Energy Balance

Question 29

It is developed from experience and field research based on assumption that the energy available for evaporation is proportional to temperature.

Answer 29

Empirical Methods