Diffusivity of 3H was measured in soil aerated zone on both natural and artificial rainfall conditions

migration of 3H tracer was also studied in loess aerated zone at the same time. The results implied that the migration velocity of 3H tracer in aerated zone was 0.03cm/d on natural condition in loess plateau of Huabei Region

the vertical diffusivity Dx was 0.10cm2/d. In the experiment pit

the migration velocity was 2.27cm/d under an artificial condition of 5mm/h sprinkling intensity for 3 hours each day

the vertical diffusivity Dx was 7.75cm2/d.