植物纤维毯对黄土沟壑区沟道边坡产流产沙及土壤的影响

为探究植物纤维毯护坡措施在黄土沟壑区对沟道边坡产流产沙和土壤的影响,采用野外人工模拟降雨试验和野外监测相结合的方法,在模拟降雨试验中,设计3个雨强,测定植物纤维毯的径流量和产沙量;在野外小区监测中,通过测定土壤物理及化学指标,评价植物纤维毯对土壤的改良作用。结果表明:植物纤维毯护坡措施在降雨强度为30 mm·h^-1、70 mm·h^-1和120 mm·h^-1时均能有效地抑制径流产沙,平均减流效益为63.33%,平均减沙效益为84.16%,减流效益和减沙效益均在降雨强度为30 mm·h^-1时最高。植物纤维毯护坡措施抑制径流产沙的效果受降雨强度影响,随着降雨强度不断增加,植物纤维毯边坡的径流量和产沙量不断增加,减流、减沙效益不同程度降低,平均径流量由降雨强度为30 mm·h^-1时的3.71 L增加到降雨强度为120 mm·h^-1时的4.22 L,平均产沙量由降雨强度为30 mm·h^-1时的10.99 g增加到降雨强度为120 mm·h^-1时的66.72 g;平均减流效益由降雨强度为30 mm·h^-1时的72.13%降到降雨强度为120 mm·h^-1时的47.76%,平均减沙效益由降雨强度为30 mm·h^-1时的88.77%降到降雨强度为120 mm·h^-1时的79.95%。植物纤维毯护坡措施可改良坡面表层土壤,植物纤维毯坡面表层土壤的土壤含水量和总孔隙度较裸坡显著提高,土壤含水率平均提高5.70%,总孔隙度平均提高13.07%,全氮和有机质含量也显著提升,全氮含量平均是裸坡的1.88倍,有机质含量平均是裸坡的2.22倍。植物纤维毯能够有效降低黄土丘陵沟壑区沟道边坡土壤侵蚀,减少产流,改善土壤理化性质,减沙效益优于减流效益。

Effects of Plant Fiber Blanket on Runoff and Sediment Yield and Soil in Gully Slopes of Loess Hilly Areas

In order to investigate the effects of plant fiber blanket on runoff and sediment yield and soil in gully slope of loess hilly area,a combination of field artificial rainfall test and field monitoring was used to measure the runoff and sediment yield of plant fiber blanket with designing three rainfall intensities in the simulated rainfall test.In the field monitoring,we have evaluated the role of plant fiber on improving the soil through measuring the soil physical and chemical indexes.The results show that the plant fiber blanket can effectively control the runoff and sediment yield with rainfall density at 30 mm·h^-1,70 mm·h^-1 and 120 mm·h^-1,the average benefits for runoff and sediment reduction is 63.33%and 84.16%,and the benefits for runoff and sediment reduction are the highest when the rainfall density is 30 mm·h^-1.With the increase of rainfall density,the runoff and sediment yields of plant fiber blanket have increased,which have reduced the benefits of runoff and sediment reduction.The average runoff has increased from 3.71 L with rainfall density at 30 mm·h^-1 to 4.22 L with that at 120 mm·h^-1.The average sediment yield has increased from 10.99 g with rainfall density at 30 mm·h^-1 to 66.72 g with that at 120 mm·h^-1.The average benefit of runoff reduction has decreased from 72.13%with rainfall density at 30 mm·h^-1 to 47.76%with that at 120 mm·h^-1.The average benefit of sediment reduction has decreased from 88.77%with rainfall density at 30 mm·h^-1 to 79.95%with that at 120 mm·h^-1.The measure of protecting slope with plant fiber blanket can improve the surface soil of the slope.The soil water content and total porosity of surface soil of plant fiber blanket are significantly higher than that of bared slope.The average soil water content is increased by 5.7%,and the total porosity is increased by 13.07%.Nitrogen and organic matter contents also increased significantly.The total nitrogen content is 1.88 times as much as that of bare slopes,and the organic matter content is 2.22 times as much as that of bare slopes.The plant fiber blanket can effectively reduce the soil erosion in loess hilly region,reduce the runoff,improve the physical and chemical properties of the soil,and the benefit of sediment reduction is better than that of runoff reduction.