Experimental study on hydraulic characteristics of overland flow under different surface roughness
ZHANG Yixuan1, MA Lan1,2，3*, XUE Menghua1, SUN Xu1, WANG Fuxing1, LI Haoyu1, SONG Tianyi1
（1 The Metropolitan Area Forest Ecosystem Research Station, School of Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China; 2 Key Laboratory of State Forestry and Grassland Administration on Soil and Water Conservation，Beijing Forestry University， Beijing 100083， China;3 Jixian Forest Ecosystem National Observation and Research Station, CNERN, Beijing Forestry University, Beijing 100083, China)
Abstract:
To further explore the law of hydraulic properties of overland flow, the hydrodynamic characteristics of overland flow under different flow rates and slopes with different roughness (0.2~0.6 mm, 0.6~1 mm, 1~1.4 mm, 1.4~2 mm, 2~3 mm particle size and smooth control group) were studied by the indoor fixedbed water scouring test. The results show that the increase of the underlying surface roughness slows down the overland flow velocity and increases the water depth. The flow velocity and water depth are well related to the flow, slope, and roughness factors as a power function. The Reynolds number reaches the maximum value in the control group, and the flow pattern tends to be slow flow with increasing roughness. The resistance coefficient positively changes with roughness and is in a good regression relationship with the power function of flow, slope, and roughness factors. The calculated runoff shear stress is well related to the measured runoff shear stress on the smooth underlying surface, and the increase of roughness has a certain effect on the increase of measured runoff shear stress. The results are significant for a deeper understanding of soil erosion mechanisms and slope erosion control.
KeyWords:
overland flow； roughness； hydraulic parameters； runoff shear stress
