Numerical simulation of soil water infiltration under rainwater collection and infiltration systems based on HYDRUS-2D
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DOI:10.7606/j.issn.1000-7601.2019.06.12
Key Words: rainwater collection and infiltration (RWCI) system  soil water content  soil water movement  HYDRUS-2D model
Author NameAffiliation
ZHANG Wei College of Water Conservancy and Architectural Engineering, Northwest A&F University, Yangling, Shaanxi 712100
Institute of Water\|saving Agriculture in Arid Areas of China (IWSA), Northwest A&F University, Yangling, Shaanxi 712100 
ZHAO Xining Institute of Water\|saving Agriculture in Arid Areas of China (IWSA), Northwest A&F University, Yangling, Shaanxi 712100
National Engineering Research Center for Water Saving Irrigation at Yangling, Yangling, Shaanxi 712100 
GAO Xiaodong Institute of Water\|saving Agriculture in Arid Areas of China (IWSA), Northwest A&F University, Yangling, Shaanxi 712100
National Engineering Research Center for Water Saving Irrigation at Yangling, Yangling, Shaanxi 712100 
WU Pute College of Water Conservancy and Architectural Engineering, Northwest A&F University, Yangling, Shaanxi 712100
Institute of Water\|saving Agriculture in Arid Areas of China (IWSA), Northwest A&F University, Yangling, Shaanxi 712100 
PAN Daili Institute of Water\|saving Agriculture in Arid Areas of China (IWSA), Northwest A&F University, Yangling, Shaanxi 712100 
SONG Xiaolin Institute of Water\|saving Agriculture in Arid Areas of China (IWSA), Northwest A&F University, Yangling, Shaanxi 712100
National Engineering Research Center for Water Saving Irrigation at Yangling, Yangling, Shaanxi 712100 
YANG Shiwei National Engineering Research Center for Water Saving Irrigation at Yangling, Yangling, Shaanxi 712100 
YAO Jie Baota District Fruit Bureau, Yan’an, Shaanxi 716000 
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Abstract:
      To understand the accumulation and infiltration of soil water in the rainwater collection and infiltration (RWCI) system, indoor soil tank tests with different irrigation amounts (10 L, 21 L, and 36 L) and RWCI design pit depths (40 cm and 60 cm) were conducted. The change of soil moisture content and the migration process of soil wetting front in radial and vertical directions under different water head changes under irrigation were observed. According to the theory of unsaturated soil hydrodynamics, the two\|dimensional infiltration model of soil moisture in the boundary condition of HYDRUS-2D variable head was established to analyze and verify the indoor tests. The results showed that the simulated and measured values of the model had good consistency, and the relative mean square error (RE), mean absolute error (MAE) and Nash coefficient (NE) of the vertical were respectively 0.019,0.011 cm,0.994, and of the radial wetting front were respectively 0.018, 0.851 cm, 0.977, and of the soil moisture content were respectively 0.188, 0.016 cm3·cm-3, 0.916. Compared with the RWCI system with a design depth of 40 cm, the RWCI system with a design depth of 60 cm increased the soil moisture content of the root distribution layer of fruit trees more effectively and increased the infiltration depth of soil moisture under different irrigation amounts. With the same irrigation amount, the RWCI system design depth had no significant difference in the radial wetting front distribution, but had a significant effect on the vertical direction distribution. Under the same design depth, the RWCI system significantly increased the wetting front in the vertical direction and the diameter as the irrigation amount being increased. The difference in migration distance gradually increased.