CHAPTER 5 Flashcards
It is the water returned to the air from a liquid to a gaseous state.
Evaporation
It is the evaporation from plants.
Transpiration
It is the combined evaporation and transpiration.
Evapotranspiration
Used interchangeably with evapotranspiration but technically, it refers to the sum of ET and water used by the plants for tissue building processes.
Consumptive Use
Give the 3 importance
- for water conservation
- for determining irrigation requirements for crops.
- for determining water storage in reservoir
What are the factors affecting evaporation?
- Meteorological Factors
- Nature of the evaporating surface
- Effects of water quality
TRUE OR FALSE:
Evaporation is directly proportional to air temperature.
True
TRUE OR FALSE:
Solar Radiation affects the degree of air saturation.
False
ans: Vapor Pressure
TRUE OR FALSE:
Vapor pressure directly affects temperature.
False
ans: Solar radiation
TRUE OR FALSE:
Solar radiation is fast in dry air.
False
ans: Evaporation
TRUE OR FALSE:
Evaporation is directly proportional to wind speed.
True
TRUE OR FALSE:
All surface exposed to precipitation are potentially evaporating surfaces.
True
TRUE OR FALSE:
The smaller the area exposed to evaporation, the faster the rate of evaporation.
False
ans: The LARGER the area exposed to evaporation, the faster the rate of evaporation.
TRUE OR FALSE:
Evaporation varies inversely with salinity of water.
True
TRUE OR FALSE:
Evaporation rate is slower in fresh water due to high vapor pressure.
False
ans: Evaporation rate is FASTER in fresh water due to high vapor pressure.
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.
True
_________ help in moisture conservation because they decrease the rate of evaporation.
Mulches
Give the 2 measurement of evaporation:
- Evaporation Pans
- Tank and Lysimeter Studies(?)
It is also called as evapotranspirimeters.
Lysimeter
Give the 4 measurement of evapotranspiration:
- Field experimental plots
- Soil water studies
- Integration methods
- Inflow-outflow method
It is the quantity of water applied in these plots is kept in small to avoid deep percolation losses and surface runoff is measured.
Field experimental plots
The samples are taken at various depths in the root zone.
Soil water studies
Defined as the water used by plants and evaporation from the water and soil surfaces are combined for the entire area involved.
Integration Methods
It is the inflow into the area (precipitation), outflow from the area and change in groundwater level are evaluated.
Inflow-outflow method
Give the 3 categories of methods of predicting evaporation and ET:
- Mass Transfer
- Energy Balance
- Empirical Methods
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.
Mass Transfer
It required measurements of wind and humidity at two or more elevations.
Mass Transfer
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.
Energy Balance
It is developed from experience and field research based on assumption that the energy available for evaporation is proportional to temperature.
Empirical Methods
