Abstract: A system of gravity-type underground hole irrigation is designed, which has double functions of rainwater collection and irrigation. Through indoor soil box test, the movement regularity of soil moisture is investigated under condition of different pressure head, hole diameter on vertical tube, and its cover-up depth. The result shows that its infiltration process can be well described by Philip infiltration model and it is found that the decision coefficient will be greater than 0.99 and the cumulative infiltration will increase with the pressure head and hole diameter. The cover-up depth of vertical tube will have slight influence on it. The wetting front movement process can be well described with power function and the wetting front movement distance will assume such a variation regularity that vertical downward movement distant will greater than horizontal one and horizontal one will greater than vertical upward one. There will be a positive correlation between the wetting front movement distance in these three directions and the pressure head and hole diameter, however, will have slight influence on the cover-up depth of the vertical tube. The infiltration of soil moisture ofgravity-type underground hole irrigation will be mainly affected by the factors such as pressure head and hole diameter.

Key words: gravity-type underground hole irrigation, soil water movement, pressure head, cover-up depth, hole diameter