| Summary: | 碩士 === 國立屏東科技大學 === 水土保持系所 === 101 === Field observations were conducted on 4 runoff plots at National Pingtung University of Science and Technology. Each plot measured 22.13m along the slope, 3m across the slope, with average gradient of 9%. In order to explore the influence by characteristics of plants on soil erosion and surface runoff, We set up a 10-m buffer at the downslope position at each runoff plot. Grass species include Carpet grass, W. trilobata and Bermuda grass. Following conclusions can be drawn from this study:
The total amount of sediment that generated from one rainy season for each plot was 9.74 kg for Carpet grass, 5.28 kg for Trilobate Wedelia, and 12.83 kg for Bermuda grass, respectively. The average sediment trapping efficiency exceeds 80%. The main factors of grass strips controlling soil erosion were vegetation cover, percentage of plant stolons coverage, and root length density (RLD). The grasses with high root length density have the least sediment yield.
During the observation period, the total runoff, for Carpet grass, Trilobate Wedelia , and Bermuda grass is 19.687 m3, 9.811m3 and 24.951m3 respectively. Average runoff coefficient of the grass strips varies from 0.06 to 0.19. The result shows that grass strip of 10-m in width is sufficient to increase runoff infiltration. Differences in plant characteristics have different impacts on surface roughness, thus lead to the ability of grasses in intercepting runoff. However, runoff formation process as well as the roots of grasses also plays an important role.
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