A modified Hargreaves equation by free search and its application in Harbin

Author

Wang Bin ; Qiang, Fu ; Min, Wang ; Chengrui, Lei

Author_Institution

Coll. of Water Conservancy & Building Eng., Northeast Agric. Univ., Harbin, China

fYear

2011

fDate

27-29 May 2011

Firstpage

78

Lastpage

82

Abstract

The reference crop evapotranspiration (ET₀) calculated from Hargreaves equation will be negative as the fixed parameters when mean air temperature is lower than -17.8°C. To improve the application of Hargreaves equation, Free Search was employed to solve the parameters of modifying Hargreaves equations based on 48-year daily meteorological data of Harbin, and the evaluation of the modified Hargreaves equations were verified by three time steps of daily, ten-day and monthly. The research results showed that the modified Hargreaves equations could solve the problem on the negative ET₀, and its accuracy is identical with the verified Hargreaves equations recommended by FAO,when ET₀ values calculated from Penman-Monteith equation was taken as standard. And what´s more, a simple method for developing Hargreaves equation was developed then.

Keywords

agricultural engineering; crops; evaporation; search problems; transpiration; Harbin; Penman-Monteith equation; free search method; modified Hargreaves equation; reference crop evapotranspiration; Agriculture; Animals; Equations; Mathematical model; Ocean temperature; Optimization; Temperature distribution; Free Search; Penman-Monteith equation; modified Hargreaves equation; reference crop evapotranspiration;

fLanguage

English

Publisher

ieee

Conference_Titel

New Technology of Agricultural Engineering (ICAE), 2011 International Conference on

Conference_Location

Zibo

Print_ISBN

978-1-4244-9574-0

Type

conf

DOI

10.1109/ICAE.2011.5943753

Filename

5943753