53:119 Hydrology
Problem #12
Pan Evaporation Methods

Actual evapotranspiration (AET) is often estimated from potential evapotranspiration (PET). A simple model for this purpose, which simulates the effect soil drying of AET, is shown below.

• AET = b · s · PET    if s < 1/b
• AET = PET    if s > 1/b
• s is the relative soil moisture content, which varies from 0 (dry) to 1 (saturated)

PET is estimated using pan evaporation measurements (E_p) and a pan coefficient (K).

Use this model to estimate AET for the following days, assuming a pan coefficient (K) of 0.7 and b of 1.25.

1. Estimate PET (inches) for each day.
2. Estimate AET (inches) for each day.