An experimental study of the influence of groundwater level on water consumption of winter wheat in the Huaibei Plain

The influence of groundwater level on water consumption of winter wheat in the Huaibei plain is examined, which is key for agricultural water management. Based on the group of large weighing lysimeters in the Wudaogou Hydrology and Water Resources experimental station from 2017 to 2020, the wheat evapotranspiration at various groundwater levels is simulated and the key environmental factors affecting wheat evapotranspiration are identified for the purpose of exploring the characteristics of wheat evapotranspiration. During the whole growth period, the wheat evapotranspiration at four groundwater levels (depth of 0.5, 1.0, 2.0 and 3.0 m) is 510.50, 499.33, 567.88, 727.88 mm, respectively. The correlation coefficient between surface soil moisture and evapotranspiration under each groundwater level is −0.51, −0.71, −0.62 and −0.72, respectively. According to the classified categories by solar radiation, three typical days are chosen with the corresponding evapotranspiration intensity of 0.30 mm/hin the strong radiation day, of 0.07 mm/h in weaker radiation day, and of 0.03 mm/h in the weakest radiation day. The peak of evapotranspiration intensity happens from 5:00 to 20:00 in the strong radiation day, from 7:00 to 17:00 in the weaker radiation day, and from 9:00 to 17:00 in the weakest radiation day. The stronger the solar radiation, the weaker the influence of groundwater level on the peak of evapotranspiration intensity. This is probably because the large groundwater levelmay block energy transmission so that the peak of evapotranspiration intensity lags behind. Surface soil is the main source of evapotranspiration, especially at depth of 1.0 and 2.0 m. Simultaneously, solar radiation, net radiation and soil heat flux drive wheat evapotranspiration positively, while surface soil moisture, average air temperature and air humidity drive contrariwise.