| A comparative study on calculation methods of reference crop evapotranspiration in the semi-arid region of Central Eastern Gansu |
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| DOI：10.7606/j.issn.1000-7601.2018.06.07 |
| Key Words: reference crop evapotranspiration Penman-Monteith method ET0 calculation method calculation result evaluaate semi-arid area |
| Author Name | Affiliation | | HUANG Cai-xia | College of Water Resources and Hydropower Engineering, Gansu Agricultural University, Lanzhou, Gansu 730070, China | | ZHAO De-ming | Gansu Engineering Consulting Center, Lanzhou, Gansu 730030, China | | WANG Bao-fu | Gansu Engineering Consulting Center, Lanzhou, Gansu 730030, China |
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| Abstract: |
| In order to obtain simplified method to calculate evapotranspiration (ET0) of reference crop when meteorological data in hilly and gully regions of central east Gansu Province is lacking. Based on long series data from 6 meteorological stations, seven methods for ET0 calculation were evaluated using the FAO Penman-Monteith as the reference method. The results showed that the best match with FAO Penman-Monteith was Hargreaves, followed by Jensen-Haise with average annual standard deviations（RMBE）of 120.0 mm and 446.1 mm, respectively. The calculated results by using Penman, FAO-17 Penman, FAO-24 Radiation, and Preiestley-Taylor were higher than that of other two methods above, and the average annual RMBE was in the range of 3 122.1~1 383.4 mm, but the results from FAO-24 Radiation differentiated the most from that of FAO Penman-Monteith. The average monthly ET0 data of all eight models showed bell shaped curves with a peak in the month of July. The difference of Hargreaves and Jensen-Haise models from the reference method in Mar. to Sept. were greater than that in Jan. to Feb. and in Oct. to Dec. Pennman, FAO-17 Penman, FAO-24 Radiation, Preiestley-Taylor, and Makkink had the greatest difference appeared in July and they were various among regions. There were significant linear correlations between the data from all the models and that from the FAO Penman-Monteith model with the regression coefficients in the range of 0.994**~0.874 3**. Therefore, it is feasible to correct the other equations using FAO Penman-Monteith model. |
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