2015 Volume 25 Issue 3 Pages 141-144
This study introduces a method of spatial prediction of reference evapotranspiration (ETo) using a modified Hargreaves empirical model for Tashkent Province, Uzbekistan. Previously, the empirical coefficient (0.0023) of the Hargreaves model was modified under local climatic conditions of Tashkent Province using standard Penman Monteih FAO 56 model estimates for every month in the vegetation period (March to September). The monthly climate data for the vegetation period were provided by Uzhydrometeorological Bureau of Uzbekistan. Statistical comparison was conducted in the ArcGIS platform (ver. 10. 2 ESRI) among deterministic and geostatistical methods to evaluate the performance of interpolation methods concerning suitability for spatial prediction of monthly averaged ETo. The best interpolation model of ETo was obtained from the Co-kriging method using elevation data as an auxiliary secondary variable. The results revealed that the incorporation of elevation data improved spatial prediction of ETo in Tashkent Province. The modified Hargreaves model provided the best performance to estimate ETo in Tashkent Province as an arid and semiarid climate. Over and under estimations of ETo with the original Hargreaves model were reduced by 65% on average when using new empirical coefficients for all 16 weather stations.
