2:2.2.4 Reading Measured or Estimated PET

Users are now able to read in daily measured or estimated potential evapotranspiration (PET) values from an external data source for each climate station. However, the user still has the option to calculate PET using the Penman Monteith, Priestley-Taylor, or Hargreaves method. The equations used to generate PET data in SWAT+ are reviewed in Chapter 2:2.2.

Using measured or estimated PET allows the model to use real observed data, which can improve accuracy and reliability. By integrating measured data, the model can account for local variations in climatic conditions that might not be captured by theoretical methods. By incorporating this functionality, the model enhances its capability to simulate real-world conditions, making it a valuable tool for hydrological studies and water resource management. SWAT+ input variables that pertain to measured or estimated PET are summarized in Table 2:2-3.

Table 2:2-3: SWAT+ input variables that pertain to measured or estimated PET.

Description	Source Name	Input Name	Input File
PET method; set to = 3 for reading in measured PET.	pet		codes.bsn
Name of PET station		pet	weather-sta.cli
File with PET measured/simulated data	petfile	pet_file	pet.cli