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| Simulation and analysis of soil water in different stages paddy field based on HYDRUS |
| MA Lihua1, HU Xiaotao2, JIANG Xianjun1, WANG Wen′e2* |
| 1. College of Resources and Environment, Southwest University, Chongqing 400715, China; 2. Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas, Ministry of Education, Northwest A&F University, Yangling, Shaanxi 712100, China |
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Abstract The process of rice paddies from flooded to drainage dry fields, the soil moisture status of paddy soil to achieve the transformation from saturation to unsaturated state. During this process, the soil moisture transport law and the transformation of the water balance factors involving soil moisture are different. In order to explore the differences of soil moisture status in different stages of rice field, based on the continuous monitoring data of soil moisture of conventional rotation rice in purple soil in Chongqing hilly area. The HYDRUS-1D model was used to verify and simulate the soil hydraulic parameters and soil content in three different dry and wet stages(stage Ⅰ, Ⅱ, Ⅲ)of rice flooding, drainage drying and post-harvest. The results indicated that: (1) according to the error analysis from R2 and RMSE results, pressure heads and vertical fluxes simulated using HYDRUS-1D matched measured data well. The HYDRUS-1D can be used to simulate the change of soil water content in the paddy field; (2) According to the analysis of soil water balance, the rice soil water in stage Ⅰ was mainly in the form of water supplement. The soil water loss in stage Ⅱ and Ⅲ is mainly water loss, and water leaching(approximately 52% and 95% in stage II and stage III, respectively)was the main path of water loss from the flood to dryland rice filed; (3) According to the simulation results of HYDRUS, the rainfall directly affects the change of upper and lower boundary flow of soil. Following the simulation results, the sunshine hours bring obvious diurnal variation rule for evapotranspiration fluxes. The actual crop transpiration and surface evaporation of stage II were lower than those of stage Ⅰ, while the actual surface evaporation of stage III was more closely related to the sunshine hours.
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Received: 29 January 2021
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