CONTROL OF GULLY EROSION USING STIFF GRASSES

查看全文 作　　者：F. D. [1]SHIELDS; Jr. [1];S. M. [1]DABNEY;E. J. [1]LANGENDOEN;D. M. [1]TEMPLE 机构地区：[1]Research Hydraulic Engineer USDA-ARS National Sedimentation Laboratory Oxford Mississippi,Research Argonomist USDA-ARS National Sedimentation Laboratory Oxford Mississippis,Research Hydraulic Engineer USDA-ARS National Sedimentation Laboratory Oxford Mississippi ,USDA-ARS Hydraulic Engineering Research Unit Stillwater, 出　　处：《International Journal of Sediment Research》索引2005年第20卷第4期,共14页 摘　　要：Concentrated flow can cause gully formation on sloping lands and in riparian zones. Current practice for riparian gully erosion control involves blocking the gully with a structure comprised of an earthen embankment and a metal or plastic pipe. Measures involving native vegetation would be more attractive for habitat recovery and economic reasons. To test the hypothesis that switchgrass (Panicum virgatum L.) hedges planted at 0.5-m vertical intervals within a gully would control erosion, a series of hedges was established in four concentrated flow channels. Two of the channels were previously eroded trapezoidal channels cut into compacted fill in an outdoor laboratory. The other two channels were natural gullies located at the edge of floodplain fields adjacent to an incised stream. While vegetation was dormant, artificial runoff events were created in the two laboratory gullies and one of the natural gullies using synthetic trapezoidal-shaped hydrographs with peak discharge rates of approximately 0.03, 0.07, and 0.16 m3/s. During these tests flow depth, velocity, turbidity, and soil pore water pressures were monitored. The fourth gully was subjected to a series of natural runoff events over a five-month period with peaks up to 0.09 m3/s. Flow depths in all tests were generally < 0.3 m, and flow velocities varied spatially and exceeded 2.0 m/s at the steepest points of the gullies. Erosion rates were negligible for controlled flow experiments, but natural flows in the fourth gully resulted in 1 m of thalweg degradation, destroying the central portions of the grass hedges, most likely due to the highly erodible nature of the soils at this site. Geotechnical modeling of soil steps reinforced with switchgrass roots showed factors of safety > 1 for step heights < 0.5 m, but instability was indicated for step heights >1 m, consistent with the experimental observations. 关 键 词：土壤侵蚀 水土流失 美国 农业土壤 农作物