Study of Factors Affecting Wheat Growth-stage Evapotranspiration under Various Edaphic Conditions

Abstract

【Objective】 The ascent of groundwater into the vadose zone and its ultimate evaporation into atmosphere is an important hydrological process. This paper investigates the impact of meteorological factors and soil texture on evaporation of shallow groundwater under different depths from winter wheat in a sandy ginger black soil and a yellow tide soil. 【Method】 The study was based on data measured from 2010 to 2022 from the Wudaogou experimental station. The relationship between groundwater evaporation and seven meteorological factors was analyzed using correlation analysis and function fitting technique. A multiple regression model, along with a nonlinear fitting function, was developed to calculate the change in evaporation of shallow groundwater with its depth ranging from 0.2 to 5.0 m. 【Result】 ① In the sandy ginger black soil, the significance of the impact of meteorological factors on groundwater evaporation was ranked in the order of surface temperature > average air temperature > surface evaporation > duration of sunshine > precipitation > wind speed; in the yellow tide soil, the ranking order was surface temperature > duration of sunshine > average air temperature > surface water evaporation > precipitation > wind speed. ② The multiple regression model is accurate for estimating evaporation of shallow groundwater at different depths, with R2>0.75 for the sandy ginger black soil and R2>0.70 for the yellow tide soil. ③ The relationship between groundwater evaporation and groundwater depth for the sandy ginger black soil followed an inverse function with R2>0.95 before the greening stage and a logarithmic function after the greening stage with R2>0.85. In contrast, in the yellow tide soil, it followed a logarithmic function with R2>0.75. ④ Depending on the growing season, the critical groundwater depth for evaporation ranged from 2.0 to 3.5 m for the sandy ginger black soil, and from 4.0 to 5.1 m for the yellow tide soil. 【Conclusion】 Groundwater evaporation depends not only on meteorological factors but also on soil texture and growing season of the winter wheat. The proposed models are accurate for estimating their relationships.

Keywords

• phreatic evaporation
• meteorological factors
• burial depth
• wheat
• huaibei plain