Influence of variable flow on sediment yield and hydrodynamic parameters of shallow gully erosion
GUO Junquan1, WANG Wenlong2
1. Yan'an Vocational and Technical College, 716000, Yan'an, Shaanxi; 2. State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, 712100, Yangling, Shaanxi, China
Abstract:[Background] The runoff usually increases with the inflow of water and rainfall above in the shallow gully, and the runoff is usually a variable. Therefore, to study the influence of runoff variation in shallow gully on the erosion and sediment yield of shallow gully in loess hilly area is a great scientific significance for soil and water loss control on Loess Plateau slope.[Methods] The shallow gully on the 26° slope in Yan'ergou watershed of Yan'an were selected as the research object, and the field drainage erosion test was conducted under the conditions of variable flow of 5-10, 10-15, 15-20 and 20-25 L/min.[Results] The effect of variable flow on sediment yield is that the average sediment yield and maximum sediment yield decrease by 8.8%-53.5% and 4.8%-66.5% respectively after variable flow. The maximum value of sediment yield before variable flow is greater than that after variable flow. The sediment yield after variable flow is different, but the trend is similar, which shows the first increase and decrease the stable; after variable flow, the trend of sediment concentration is the same, It is manifested as:start to increase to reach the maximum The influence of variable flow on sediment concentration is that the sediment concentration before variable flow is greater than that after variable flow, and the average sediment concentration and maximum sediment concentration decrease by 31.9%-55.7% and 42.6%-69.0% respectively, compared with that before variable flow, the average velocity after variable flow decreases by 6.8%-18.1%, and the maximum velocity and average velocity after variable flow are smaller than that before variable flow The reduction of velocity before variable flow is greater than that after variable flow. The resistance coefficient increases by 1.55-2.55 times after variable flow rate compared with that before variable flow rate.[Conclusions] In the process of large runoff, the sediment yield, sediment concentration and runoff velocity increase with the increase of flow, and the resistance coefficient decreases with the increase of flow, but the overall trend increases. Therefore, in the process of prevention and control of runoff and soil loss in shallow gully measures should be taken to prevent the increase of runoff and reduce soil erosion.
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