TEMPORAL AND SPATIAL DISTRIBUTION OF REFERENCE CROP EVAPOTRANSPIRATION IN NORTH CHINA PLAIN

Reference evapotranspiration (ETo) is the main influencing factor of crop water balance.Based on data from 170 meteorological stations in the North China Plain (NCP) from 1970 to 2019, moving average method, Mann-Kendall test, improved ordered cluster analysis, inverse distance weighted interpolation (IDW), ordinary least squares regression (OLS), geographically weighted regression (GWR) and hotspot analysis, were used to analyze the spatial and temporal variation of ETo in NCP.The ETo in NCP showed a significant decreasing trend with 99% confidence.The high ETo value range (1085~1039 mm/year) appears in the west and south of Bohai Bay.The northern part of the Bohai Bay witnessed relatively low ETo value (909~997 mm/year).It is qualitatively judged that wind speed is the main factor affecting ETo in NCP.Results by the GWR model further confirm that wind speed was the dominant factor affecting ETo in NCP.Based on the hotspot analysis, it was found that the hot spots shrank sharply, and the hot spots were more likely to become areas with high ETo values over time.Results of this study can help in better understanding the spatial and temporal distribution of regional ETo in NCP and allocation of agricultural water resources.