Evaluating Methods of Estimation and Modelling Spatial Distribution of Evapotranspiration in the Middle Heihe River Basin, China
Chuanyan Zhao, Zhongren Nan and Guodong Cheng
DOI : 10.3844/ajessp.2005.278.285
American Journal of Environmental Sciences
Volume 1, Issue 4
Seven models commonly used to estimate the daily reference evapotranspiration (ET0) were evaluated in the middle Heihe River Basin of the arid northwestern part of China. The objectives of the study are to choose the appropriate model for estimating the areal distribution of ET0 and to explain the spatial-temporal distribution of the same through GIS in the study area. The results indicated that the FAO-Penman model is the best way to estimate ET0; its RMSE ranged from 1.11 to 1.70 mm, and r2 from 0.59 to 0.93. The spatial variations of ET0 are higher in the western part than in the middle-eastern part of the study area. The temporal variations of daily differences in ET0 rates are mainly due to the differences in irradiance (Rn) and to daily differences in the vapor pressure deficit (D). The spatially modeled ET0 results (r2 = 0.88) are in agreement with the corresponding data in situ on the 15th of each month.
© 2005 Chuanyan Zhao, Zhongren Nan and Guodong Cheng. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.