DETERMINATION OF EVAPOTRANSPIRATION USING SOLAR RADIATION AND METEOROLOGICAL DATA APPLYING DIFFERENT METHODS: A CASE STUDY HOA BINH PROVINCE

Tóm tắt

Evapotranspiration (ET) is a significant parameter that needs to be determined and accurately estimated in many practical applications such as the management and use of water domestic, agricultural production, and forestry. The content of the article presents four methods that include the Makkink method (1957), Abtew method (1996), Priestley & Taylor method (1972), Hargreaves & Samani method (1982, 1985) to calculate evapotranspiration from meteorological data at monitoring stations in Hoa Binh province. The results of evapotranspiration calculated from the methods are compared and evaluated for accuracy with direct measurement data at the province's hydro-meteorological stations, attend to the management, forecasting water demand in agriculture and forestry, and design of irrigation works with climate conditions of Hoa Binh province. The results indicate that the average evapotranspiration values at the hydro-meteorological stations of Makkink method (1957), Abtew method (1996), Priestley & Taylor method (1972), Hargreaves & Samani method (1982, 1985) to calculate evapotranspiration from meteorological data at monitoring stations in Hoa Binh province. The results of evapotranspiration calculated from the methods are compared and evaluated for accuracy with direct measurement data at the province's hydro- meteorological stations, attend to the management, forecasting water demand in agriculture and forestry, and design of irrigation works with climate conditions of Hoa Binh province. The results indicate that the average evapotranspiration values at the hydro-meteorological stations of Makkink method (1957), Abtew method (1996), Priestley & Taylor method (1972), Hargreaves & Samani method (1982, 1985) on 04th June 2017 were 8.1 mm, 5.8 mm, 7.8 mm and 11.3 mm, respectively. The average error of evapotranspiration at meteorological stations calculated according to the methods compared with the average evapotranspiration at meteorological stations measured directly is 5.2%, 24.7%, 1.3%, 46.7%, respectively. Calculating evapotranspiration by the Makkink method with coefficients a = 0.9 and b = 0 gives the most accurate results with the highest correlation coefficients R2 = 0.969 and RMSE = 0.346. According to the results, the Priestley- Taylor and Makkink method is proposed to calculate the evapotranspiration for the Hoa Binh area.