A user-friendly interactive tool for estimating reference ET using ASCE standardized Penman-Monteith equation

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.