Spatial Interpolation of Daily Reference Evapotranspiration in Northwest Texas.

Several hydrological and agricultural studies, such as water resources management, land use planning, irrigation scheduling, crop water requirements, etc., it is often necessary to estimate reference evapotranspiration at points located some distance from a weather station. For regions which are served by weather station networks, estimating a specific value at other points are possible using interpolation methods from surrounding weather station’s data. The objective of this study was to evaluate different methods to interpolate daily reference evapotranspiration in Northwest Texas. Weather data including reference evapotranspiration of different weather stations were collected from West Texas Mesonet (www.mesonet.ttu.edu). The different methods of spatial interpolation (e.g., Inverse Distance Weighting, spline, ordinary kriging and cokriging) of reference evapotranspiration were evaluated. Weather stations were divided into two sets to validate and compare the studied interpolation methods (k-fold cross-validation). Three criteria: mean error, mean absolute error and root mean squared error, were used to evaluate the performance of the interpolation methods.