A User-Friendly Interactive Tool for Estimating Reference ET Using ASCE Standardized Penman-Monteith Equation

Abstract.

The Accurate daily reference evapotranspiration (ET) values are needed to estimate crop water demand for irrigation management and hydrologic modeling purposes. The Bushland Reference ET Calculator (BET) was developed to implement a user-friendly interface for calculating hourly and daily grass and alfalfa reference ET using the Java Programming Language. The calculator uses the American Society of Civil Engineers (ASCE) Standardized Reference ET equation for calculating both grass and alfalfa reference ET at hourly and daily time steps from a single set or time series of weather data. Daily reference ET can be calculated either by calculating the hourly reference ET values and summing them up or by calculating a daily value using daily statistics of the climatic data (means, maxima, and minima). Graphing capabilities include line graph and scatter plot for quality assurance and quality control purposes. Descriptive statistics can be calculated for selected or all of the variables. Although the “Bushland Reference ET Calculator” was designed and developed for use mainly by producers and crop consultants to manage irrigation scheduling, it can also be used in educational training, research, and other practical applications. This article demonstrates the use of the Bushland Reference ET Calculator that is available from the USDA-ARS Conservation and Production Research Laboratory web site to interested users at no cost.