USDA SSURGO data (http://sdmdataacc

USDA SSURGO data (http://sdmdataaccess.nrcs.usda.
gov/) is downloaded to obtain soil physical properties and the total
available water (TAW), both of which are utilized to determine the
soil water profile range. Additionally, weather variables required to
calculate the ASCE-EWRI (2005) hourly alfalfa reference evapotranspiration
(ETr), which include: solar radiation, air temperature,
relative humidity and/or vapor pressure, and wind speed are downloaded
from CoAgMet (http://www.coagmet.colostate.edu/) and
NCWCD (http://www.northernwater.org/WaterConservation/
WeatherandETInfo.aspx) weather stations. Crop coefficient curves
(Kcr) which adjust ETr to crop ET (ETc) are currently being validated
for use within Colorado.