Influences of grass and moss on runoff and sediment yield on sloped loess surfaces under simulated rainfall

✍ Scribed by Chengzhong Pan; Zhouping Shangguan; Tingwu Lei

• Publisher: John Wiley and Sons
• Year: 2006
• Tongue: English
• Weight: 141 KB
• Volume: 20
• Category: Article
• ISSN: 0885-6087
• DOI: 10.1002/hyp.6158

✦ Synopsis

It is important to evaluate the impacts of grasses on soil erosion process so as to use them effectively to control soil and water losses on the Loess Plateau. Laboratory-simulated rainfall experiments were conducted to investigate the runoff and sediment processes on sloped loess surfaces with and without the aboveground parts of grasses and moss (GAM: grass and moss; NGAM: no grass and moss) under slope gradients of 5 °, 10 °, 15 °, 20 °, 25 °and 30 °. The results show that runoff from GAM and NGAM plots increased up to a slope gradient of 10 °and decreased thereafter, whereas the runoff coefficients increased with gradient. The average runoff rates and runoff coefficients of NGAM plots were less than those of GAM plots except for the 5 °slope. This behaviour may be due to the reduction in water infiltration under moss. The difference between GAM and NGAM plots in average runoff rates varied from 1Ð4 to 8%. At the same gradients, NGAM plots yielded significantly (˛D 0Ð05) more sediment than GAM plots. Average sediment deliveries for different slopes varied from 0Ð119 to 3Ð794 g m 2 min 1 from GAM plots, and from 0Ð765 to 16Ð128 g m 2 min 1 from NGAM plots. Sediment yields from GAM plots were reduced by 45 to 85%, compared with those from the NGAM plots. Plots at 30 °yielded significantly higher sediments than at the other gradients. Total sediments S increased with slope gradients G in a linear form, i.e. S D 9Ð25G 39Ð6 with R 2 D 0Ð77 Ł , for the GAM plots, and in an exponential model, i.e. S D 40Ð4 exp(0Ð1042G) with R 2 D 0Ð93 ŁŁ , for the NGAM plots. In all cases, sediment deliveries decreased with time, and reached a relative steady state at a rainfall duration of 14 min. Compared with NGAM plots, the final percentage reductions in sediment delivery from GAM plots were higher than those at the initial time of rainfall at all slopes.