3.2. Variation in erosion sediment yield
In all four slopes and most vegetation covers, erosion sediment yield
was greatest in the first 5 minutes (Fig. 5). Thereafter, sediment yield
dropped to less than a third of the maximum value and remained
relatively constant throughout the rest of the sampling period. The
interaction of slope with vegetation cover was as expected: on steeper
slopes more sediment eroded in plots with 0% vegetation cover. On all
slopes, 30% vegetation cover effectively decreased sediment erosion to
almost
zero.
[Insert Figure 5]
Under different vegetation covers,
the difference of erosion sediment yield at the 5° slope was smaller
(Fig. 6). Meanwhile, under vegetation covers and slopes as well as their
combined effects, the difference of erosion sediment yield at the 10°
slope with 30% vegetation covers was smaller too (Fig. 6c). On the
whole, the difference of erosion sediment yield was larger at the 10°
and 15° slope with different vegetation covers and it was significantly
larger than that at 5° slope. At the 20° slope with 0% and 30%
vegetation covers, however, the difference was smaller and it was
gradually smaller than that at 15° slope. The result indicated that the
effect of vegetation covers, slope factor and their interaction on
erosion sediment yield was considerable at the 10° and 15°slope.
[Insert Figure 6]