Steve Mauget and Gary Leiker
USDA-ARS Plant Stress & Water Conservation Lab
The Ogallala Agro-Climate Tool is a Visual Basic application that estimates irrigation demand and crop water use over the Ogallala Aquifer region. The application can be installed on any Windows PC with a Pentium III or better processor running Windows 2000, XP, Vista, Windows 7 or higher. Once it is downloaded and installed, instructions for the application's use can be found by left single-clicking on the 'Help' button on the application's upper left corner.
The application's meteorological database consists of daily precipitation and temperature data from 141 U.S. Historical Climatology Network stations during 1976-2005. From that daily data the program calculates climate and crop evapotranspiration (ETc) statistics over arbitrarily defined periods within summer or winter growing seasons at user-selected latitude-longitude coordinates. The statistics reported include: ETc estimates derived from the FAO-56 single crop coefficient algorithm, probabilities of exceedance of cumulative rainfall, irrigation demand and growing degree days, the probability that minimum and maximum daily temperatures will exceed user-defined temperature thresholds, and the probability of heat stress, cold stress and dry periods of varying duration.