The source of sediment transported by raindrop induced saltation

摘要

The movement of particles traveling by raindrop induced saltation from 5 equally long segments on bare planar slopes 0.8m to 20m in length inclined at 5% was simulated under 100mmh~(-1) rain with drops of 2.7mm in size. Initially, the sediment discharges were dominated by material detached from near the downstream boundary but, as time progressed, the dominant source moved upslope as particles detached in the upslope areas contributed to the sediment discharge. On the 20m long slope, the top 4m long slope segment was the dominant contributor to the discharge at the steady state. This result is consistent with the relative degree of protection against detachment provided by the shallow flows in that segment. However, on the 4m long slope, although the uppermost 0.8m long segment had the highest potential for detachment, the capacity to transport material from that segment was restrictive and the dominant source at the steady state occurred further down the slope. The results of the simulations indicate that if the slope is divided into a number of equally long segments, the segment contributing to the greatest source of the sediment discharged by raindrop induced saltation at the steady state moves down the slope as slope length is reduced.