Abstract: According to the equation of one-dimational flow through unsaturated homogenous soil and the consideration of plant transpiration and soil surface evaporation, a mathematical model has been developed using the ALPHA computer to simulate the soil water movement in the population of Populus beijingensis seedlings. Results indicate that the predictive data are nearly in accordance with the determinative, their relative errors generally under 5%, the maximum of them under 8% too.

Key words: One-dimational flow, Unsaturated homogenous soil