Abstract:

Soil tank (3 m×1 m) of variable slope was taken for artificial rainfall and runoff scouring test. The features of runoff and sediment yield on purple soil slope in the presence of different slope gradients (5°~20°), rainfall intensities(0.6~2.5 mm/min), and scouring flow rates(1.6~7 m³/s) were researched. Results indicate that in scouring test, the runoff flow velocity from slope top to slope toe changes in three tendencies: first increases and then reduces, progressively increases, and progressively reduces; whereas for artificial rainfall test, the runoff flow velocity gradually increases from slope top to slope toe. The critical time of runoff getting stable in both tests is 15min; whereas for sediment concentration, the time of getting stable is between 5~50min in artificial rainfall test and 20min in scouring test.

Key words: purple soil, runoff velocity, sediment concentration, artificial rainfall, scouring