研究論文
Development of Mini Portable Pressure Head Type Rainfall Simulator for Investigating Runoff, Infiltration and Sediment Discharge
2019 年 87 巻 2 号 p. I_297-I_302
詳細
2019 年 87 巻 2 号 p. I_297-I_302
A Mini Portable Pressure Head (MPPH) type Rainfall Simulator was developed for investigating runoff, sediment and infiltration from the soil in laboratory. The raindrops were produced from 175 pieces of φ 0.34 mm needles which were embedded under the drop former. The uniformity coefficient of the simulated rainfall was 84.3%. The drop velocity 5.2 m s-1 and kinetic energy was 0.263 J m-2 s-1 for rainfall intensity of 70 mm h-1.
The investigations of runoff, sediment discharge and infiltration were conducted using the Andosol soil with the average dry bulk density of 0.58 × 103 kg m-3 and the volumetric moisture content at the field capacity of 0.39 cm3 cm-3. The simulation was set for the rainfall intensity of 70 mm h-1 on the lysimeter surface at 5% slope. The runoff and infiltration samples were collected each 10 minutes during the experiment of 100 minutes.
The runoff occurred about 98 ± 44.5 seconds after the rainfall simulation started and rapidly increased to be 52 mm h-1 while infiltration outflow occurred after 60 minutes with average flow of 17 mm h-1. The average sediment concentration in discharge water was about 5.99 g L-1 and cumulative sediment discharge was about 3.81 t ha-1 h-1. The developed rainfall simulator was able to produce useful datasets for runoff, infiltration and sediment discharge.
