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| DOI：10.13522/j.cnki.ggps.2020482 |
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| Spatiotemporal Variation of Crop Coefficient of Winter Wheat in Huaibei Plain |
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HUA Jiacheng, ZHU Yonghua, WANG Zhenlong, LYU Haisheng
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1. Hohai University, Nanjing 210098, China; 2. State Key Laboratory of Hydrology and Water Resources and Hydraulic Engineering Science, Hohai University, Nanjing 210098, China; 3. Water Resources Research Institute of Anhui Province, Bengbu 233000, China
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| Abstract: |
| 【Background】Water uptake by plants and its subsequent transpiration is an important process in the hydrological cycle but difficult to measure and calculate. In irrigation management, the evapotranspiration is often calculated from the reference evapotranspiration multiplied by a crop coefficient.【Objective】The purpose of this paper is to study the spatiotemporal variation of the crop coefficient of winter wheat in Huaibei plain of China.【Method】Using data measured from 1991 to 2018, we calculated the crop coefficient of the winter wheat based on water balance method, eddy covariance measurements and the Bouchet complementary relationship theory. The reference evapotranspiration was calculated from the Penman-Montieth formula. The spatiotemporal variation of the crop coefficient and its determinants were calculated using linear fitting method, Mann-Kendall trend test, Mann-Kendall jump test and moving t-test, and the ArcGIS. 【Result】The annual mean evapotranspiration during the growth season of the winter wheat in Huaibei plain is 429.3 mm, and the reference crop evapotranspiration and the crop coefficient were 541.3 mm and 0.79 respectively. As the wheat grew, its crop coefficient decreased first and then increased, followed by a decline. Spatially, the crop coefficient was lowest at the northwest corner, and it was higher in the north than in the south. Temperature affected the crop coefficient most, followed by relative humidity and precipitation; it was least affected by wind speed. 【Conclusion】 The spatiotemporal variation of crop coefficient of winter wheat calculated for Huaibei plain provided guidance for calculating water requirement by irrigation. In particular, we found that the crop coefficient had been in increase from 1991 to 2018 possibly due to the climate change, which needs to be considered in evaluating water requirements in agricultural structure design for this region. |
| Key words: crop coefficient; real evapotranspiration; reference crop evapotranspiration; Huaibei plain; winter wheat |
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