JOURNAL OF NANJING FORESTRY UNIVERSITY ›› 2019, Vol. 43 ›› Issue (02): 114-120.doi: 10.3969/j.issn.1000-2006.201805029

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Effects of rainfall and slope gradient on runoff and sediment yield of subgrade slope

WANG Baoyi1, ZHANG Ronghua2*, JING Shasha2, LI Huan3, ZHANG Chunqiang3, LI Jiazuo3, SONG Yuanyuan1, LUO Mengqi1, ZHANG Guangcan2   

  1. (1. College of Forestry, Nanjing Forestry University, Jiangsu Key Laboratory of Soil and Water Conservation and Ecological Restoration, Co-Innovation Center for the Sustainable Forestry in Southern China, Nanjing 210037, China; 2. The Key Laboratory of Soil Erosion and Ecological Restoration of Shandong Province, Forestry College of Shandong Agricultural University, Tai'an 271018, China; 3. Water and Soil Conservation Monitoring Center of Huaihe Water Resources Commission, Benbu 233001, China)
  • Online:2019-03-30 Published:2019-03-30

Abstract: 【Objective】Understanding the effects of rainfall and slope gradient on runoff and sediment yield of railway subgrade slope could provide technical support for soil and water loss monitoring during the construction of railway subgrade in the Jiaodong Peninsula region.【Method】By using rainfall simulation combined with three rainfall intensities(20 mm/h, 40 mm/h, and 60 mm/h)and two slope gradients(30° and 35°), the effects of rainfall and slope on runoff and sediment yield of railway subgrade slope were evaluated in the Jiaodong Peninsula region.【Result】Under the rainfall simulation, runoff starting time decreased by 56-73 s, with rainfall intensity increasing from 20 mm/h to 60 mm/h within the same slope gradient. Meanwhile, the starting time of runoff decreased by 2-23 s as the slope changed from 30° to 35° under the same rainfall intensity. Runoff and sediment yield increased sharply, reaching a peak during the early period of rainfall, and runoff gradually stabilized and the sediment yield decreased and gradually stabilized with time. Under the same slope gradient, runoff and sediment yield increased by 37.8%-115.2% and 67.0%-86.9%, respectively, when rainfall intensity increased from 20 mm/h to 40 mm/h. Furthermore, runoff and sediment yield increased by 54.7%-125.0% and 144.5%-177.9%, respectively, when rainfall intensity increased from 40 mm/h to 60 mm/h. Under the same rainfall intensity, the critical slope of runoff and sediment yield was located within the slope gradient between 30° and 35°. With low rainfall intensity(20 mm/h and 40 mm/h), the slope was the main factor for runoff and sediment yield, and runoff and sediment yield of 35° were less than that of 30°. However, when the rainfall intensity was 60 mm/h, rainfall was the main factor and the runoff at 35° was greater than 30°, though sediment yield was less than 30°.【Conclusion】Rainfall and slope gradient have an effect on the starting time of runoff, and results from this study provide reference data for soil erosion monitoring of railway subgrade in the Jiaodong Peninsula region.

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