Effectiveness of geotextiles for road slope protection under simulated rainfall

Geotextiles are used to control soil losses in civil engineering. The effects of geotextiles on runoff and soil erosion have been documented; however, the conditions studied to date have been limited and are insufficient for the optimization of the selection and application of geotextiles for other sites. As a result, systematic studies of various rainfall intensities are still required. In this study, four geotextiles (coir blanket-CB, mixed coir and straw blanket-MCSB, straw blanket-SB and nonwoven fabric-NB) and a bare control group were examined under simulated rainfall events. Four rainfall intensities (24, 47, 71 and 93 mm h(-1)) were simulated for 60 min. The plots used in this experiment were 200 cm long by 100 cm wide by 40 cm deep at a slope gradient of 70 %. The tested soil was sandy loam, which is a primary soil type in northern China. The results show that geotextiles are more effective for soil loss control than for runoff control, especially in the case of stronger rainfall events. The effectivenesses of the geotextiles at reducing runoff and soil erosion decrease with increasing rainfall intensity; the geotextiles are most effective under moderate rainfall intensity levels. NB is the most effective geotextile for reducing runoff, while it reduces soil loss only below a rainfall intensity level of 47 mm h(-1). The natural geotextiles can reduce both runoff and soil erosion. For runoff control, SBs are more effective than MCSB, followed by CBs. For soil erosion control, CBs are the most effective, followed by MCSBs and then SBs.