Resources Science ›› 2019, Vol. 41 ›› Issue (10): 1780-1790.doi: 10.18402/resci.2019.10.02

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Applicability of six potential evapotranspiration estimation methods in Liaoning Province

CAO Yongqiang,LIU Mingyang,LI Yuanfei,XIAO Chunliu   

  1. School of Geographical Sciences, Liaoning Normal University, Dalian 116029, China
  • Received:2019-03-15 Revised:2019-07-16 Online:2019-10-25 Published:2019-10-25

Abstract:

Accurate estimation of potential evapotranspiration (PET) is a basis for studying regional hydrological cycles and agricultural irrigation management. In this study, six estimation methods Penman-Monteith (PM) method, Rohwer (Roh) method, Hamon (Ham) method, Hargreaves (Har) method, Makkink (Mak) method, and Priestley-Taylor (PT) method were tested based on historical meteorological data of 27 meteorological stations in Liaoning Province and surrounding areas from 1968 to 2017. Potential evapotranspiration was calculated by the Makkink (Mak) method and the Priestley-Taylor (PT) method. The PM method was used as the standard to correct the empirical coefficients of the five estimation methods. Then, the application of the five estimation methods for annual and monthly PET in Liaoning Province before and after the correction of the empirical coefficients was analyzed. The results show that: (1) Before the correction, the results of the Mak, PT, and PM methods are relatively close, and the relative errors are all within 25%. On the monthly scale, the relative error of the PT method is the lowest (13.96%), followed by the Mak method. Spatially, the five estimation methods have lower estimation accuracy in the northeastern part of the province, and the overall spatial difference is obvious. Comparatively, the PT method is more applicable. (2) After the amendment, the applicability and correlation of the five estimation methods are clearly improved. On the annual scale, the estimation results are almost the same as the inter-annual changes of the PM method. The Mak and PT methods are most suitable, and their relative errors are all within 10%. On the monthly scale and with regard to the spatial pattern, the PT method is superior to other methods. Therefore, when calculating PET in Liaoning Province, we recommend using the PT method after the correction of the empirical coefficients, followed by the Mak method.

Key words: potential evapotranspiration, estimation method, applicability, empirical coefficient, PM method, Mak method, Liaoning Province