Continental-scale spatiotemporal calibration of the Blaney–Criddle equation for different climate zones in China

Abstract

Study regionChina Study focusThis study focuses on the continental-scale spatiotemporal calibration of the Blaney–Criddle equation (BC) for different climate zones in China. Daily meteorological data from 82 weather stations in China were collected for the periods of 1970–2004 and 2005–2014, respectively, to calibrate and validate the BC model. The coefficients of the BC model were spatially and temporally calibrated in different climate types via a linear regression method. New hydrological insights for the region(1) Performance of the quarterly calibrated BC model was the most satisfactory. Statistical indices were in the range of 0.449–0.797 mm d−1 for the mean absolute error, 0.567–0.969 mm d−1 for the root mean square error and 0.82–0.953 for the index of agreement. The accuracy ranges increased from 42.95–96.56 % to 87.18–98.74 %; (2) Correction coefficient b and a for every quarter was mapped. Value of b showed a bell-shaped consist with temperature, while a showed an opposite trend. The quarterly calibrated BC model provided satisfactory results in the temperate monsoon and temperate continental climate zones; and (3) results indicated maximum temperature was the most influential factor for reference evapotranspiration (ET0), followed by minimum temperature. This study provides a more accurate BC model to calculate ET0 for different climate types in China and a reference for agricultural decision-makers in irrigation areas that lack sufficient meteorological data.