What fundamental approaches are integrated into the Penman equation for estimating evapotranspiration?
Energy balance and mass transfer
Penman Equation Components
The Penman equation is a method used to calculate potential evapotranspiration (ET). It fundamentally integrates two distinct physical processes:
- Energy Balance: This component accounts for the energy available at the surface that drives evaporation. It primarily relies on factors like net radiation and ground heat flux.
- Mass Transfer (Aerodynamic): This component addresses the capacity of the atmosphere to remove the water vapor produced by evaporation. It is influenced by factors such as wind speed and the saturation deficit of the air (related to vapor pressure gradients).
By combining the principles of energy balance (how much energy is available) and mass transfer (how efficiently vapor can be removed), the Penman equation provides a comprehensive estimate of evapotranspiration.
Important Questions from Runoff
The total quantity of surface water that can be expected in a given period from a stream at the outlet of its catchment is known as ______.
- A 3-hour storm on a small drainage basin produced rainfall intensities of 3.5 cm/hr 4.2 cm/hr and 2.9 cm/hr in successive hours. If the surface runoff due to storm is 3 cm, then the value of ϕ-index will be:
Which of the following statements is INCORRECT with regards to runoffs?
Maximum surface run-off is because of
Select the correct option for the given statements.
Statement 1: Runoff is a function of precipitation, intensity, duration and its coverage.
Statement 2: The size of catchment has a definite effect on the runoff. More the area, lesser will be the runoff.
