Numerical simulation of soil water movement by gravity subsurface hole irrigation

Abstract

Aridity and soil erosion are two bottlenecks restricting the sustainable development of the Loess Plateau and are also fundamental reasons for the ecological fragility of the region. A gravity subsurface hole irrigation system was proposed to regulate rainfall–runoff, achieve rainwater stylization, and reduce soil erosion. Based on HYDRUS-2D/3D, a mathematical model of soil water movement under gravity subsurface hole irrigation was created. Thirty-five scenarios were designed to analyze five cumulative infiltration volumes (I) and wetting front migration distance (W), and changes under different combinations of saturated hydraulic conductivity (Ks), infiltrating hole diameter (D), infiltrating pipe depth (B), matric potential (Ψm), and infiltration time (T). The results indicated that when Ks, D, B, and T increased, I also increased, while Ψm increased and I decreased. In addition, when I and Ψm increase, W increases. However, when D and B increase, W decreases. Ks promotes W in a vertical downward direction but inhibits W in the vertically upward and horizontal directions. The simulation results established the I estimation model and the W estimation model (power function continuous multiplication form). There was acceptable uniformity among the predicted and measured values, and its reliability was verified experimentally.