Spatial and Temporal Characteristics of Infiltration Wetting Front of Ring-shaped Root Emitters

Abstract Ring-shaped root emitter is a new type of emitter applicable to the roots of fruit trees in arid areas. To study the characteristics of infiltration wetting front changes of ring-shaped root emitters, nine scenarios were designed using the orthogonal test method, including four factors (i.e., irrigation ring radius, burial depth, number of orifices and irrigation water amount) and their three levels. The infiltration process of these nine scenarios was simulated using HYDRUS-3D software. The results show that the interference infiltration time exhibited a good power function relationship with the irrigation ring radius, number of orifices and burial depth; the wetting fronts before the interference infiltration were all in the shape of a rotating ellipsoid centered on the infiltration point and can be expressed by the equations of the upper and lower semi-elliptic curves relative to the infiltration point. With the increase of time, the wetting fronts were centered at the infiltration point and infiltrated in all directions. The transport rate decreased with time. The power function relationship between the wetting fronts and the influencing factors after the interference infiltration in different directions was established, and the coefficient of determination was above 0.888. The wetting front shape after infiltration stabilization can be regarded as a rotating body formed by the vertical wetting front plane around the z-axis. The Wetted soil volume of deep percolation, surface and suitable infiltration scenarios was rugby-shaped, apple-shaped with a flattened top and complete apple-shaped, respectively. The research results can provide a reference for selecting root emitter parameters and layout as well as developing a root irrigation system.