Experimental Research On Infiltration Of Film-Furrow Irrigation

Film-furrow irrigation is a technique combining furrow irrigation and film-covering techniques. Film-furrow is formed by covering film with holes on furrows, and water moves on the film in furrow and infiltrates throw the holes. The infiltration rules, such as variation of cumulative infiltration with time, dynamic change of wetted body shape and the development of wetting front and regularities of water distribution in wetted body, play important role in determing the lay format of holes and other parameter and performance evaluation. This work provides a theoretical ground for film-furrow irrigation.An experimental device for film-furrow irrigation was developed and used in infiltration experiment with 5 treatments under different lay formats of hole to observe the cumulative infiltration, horizontal wetting front, vertical wetting front at different time etc. The fitting results show that Kostiakov-Lewis model is batter than Kostiakov model, and the relation between both horizontal wetting front and vertical wetting front and time can be well fitted by power function. According to dye tracer selection and model calibration, we adopted dye infiltration to observe soil water and soil water content contour diagrams for each layer were obtained, and regularities of water was analysised as well. The analysis results indicate that the deeper of horizontal profile the more uniform water distribution. The main results of this work are as follows:1. The variation of cumulative infiltration can be well fitted using Kostiakov-Lewis model, but not the Kostiakov model; the relation between both horizontal wetting front and vertical wetting front and time can be well fitted with power function; the model is sensitive to the layout and diameter of holes.2. Soil water content is well-regulated. The uniformity of soil water distribution on horizontal profile increases with depth, and the uniformity of spatial water distribution increased with time.3. The experimental device provides a good physical analogue to film-furrow irrigation.4. It is feasible to observe soil water distribution by dye infiltration combining computer information abstracting technique, which overcomes the difficulty in 3-D infiltration observation, and provides precise data for computer simulation in future.Further investigation into the film-furrow infiltration rules as follows are necessary: The affection of soil texture, soil density, initial water content, quality of film-cover and other factors etc. to infiltration, and the development characteristics and rules of soil water distribution.