Location: Soil and Water Management Research
Title: Spatial variability insensitivity coefficient of grass and alfalfa reference evapotranspiration in the Texas High Plains Authors
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: February 1, 2014
Publication Date: April 7, 2014
Citation: Moorhead, J.E., Gowda, P., Marek, G.W., Porter, D.O., Marek, T.H., Howell, T.A. 2014. Spatial variability insensitivity coefficient of grass and alfalfa reference evapotranspiration in the Texas High Plains [abstract] ASABE Paper No. 18748. Technical Abstract: Evapotranspiration (ET) is a major component of the agricultural water budget and accurate ET estimations are essential for effective irrigation scheduling. Therefore, it is an important aspect of production agriculture and agricultural research. Potential ET of a crop can be calculated by multiplying reference ET by an appropriate crop coefficient. Reference ET can be estimated from meteorological data obtained from weather data collected on a reference crop surface, e.g. grass or alfalfa. However, sensor inaccuracies in a weather station may propagate measurement errors into the reference ET calculations. A sensitivity analysis of ET parameters (air temperature, wind speed, solar radiation, and relative humidity) can be used to determine the accuracy levels needed for their measurements. In this study, we conducted sensitivity analysis of weather parameters on the daily reference ET using hourly data (1995-2008) from eight weather stations managed by the Texas High Plains ET network in the Texas Panhandle. Sensitivity coefficients were calculated for each of the weather parameters. Comparison of the sensitivity coefficients for any one station indicated that reference ET was most sensitive to wind speed followed by the air temperature. Comparison of sensitivity coefficients for any one weather parameter (e.g. wind speed) across the region showed no significant differences in the sensitivity of reference ET to those parameters. This indicates that the existing N-S air temperature gradient and variability in local wind circulation patterns have limited influence on the sensitivity of reference ET to individual weather parameters.