裸露砒砂岩区坡面侵蚀过程中地表粗糙度与水力侵蚀特征参数的关系

Relationship Between Surface Roughness and Hydraulic Erosion Characteristic Parameters During Slope Erosion in Exposed Pisha Sandstone Area

坡面地形起伏状况是影响土壤侵蚀状况的重要因素,深入了解地表粗糙度和产流产沙以及水动力参数之间的关系是研究坡面土壤侵蚀过程的基础。采用野外原位模拟冲刷试验,使用三维激光扫描仪结合ArcGIS提取地形因子参数,研究了裸露砒砂岩区坡面侵蚀过程中地表粗糙度与侵蚀特征参数的关系。结果表明:(1)冲刷强度的增大使得阻力特征参数逐渐降低,且随着冲刷时间的增加,弗劳德数也呈现降低趋势,其他水力学参数呈增大趋势。冲刷强度<200 L/h时,坡面径流处于层流状态,随着冲刷强度增大,流态呈现出缓流向急流转化的趋势。(2)地表粗糙度随着冲刷流量的增大变化规律不明显。当冲刷强度较小时(<100 L/h),地表粗糙度与产流产沙特征参数的关系较为密切。(3)流速与地表粗糙度呈显著的幂函数关系(R2>0.561),是反映地表粗糙度变化的最优参数。(4)通过Mantel相关分析发现,随着冲刷强度的增大,地表粗糙度的变化规律由产流产沙特征向水动力参数特征转变。研究结果旨在揭示地表粗糙度与土壤侵蚀过程特征参数的关系,为裸露砒砂岩区坡面土壤侵蚀模型的构建提供理论依据。

Slope topographic relief is an important factor affecting soil erosion.The relationship between surface roughness,sediment yield and hydrodynamic parameters is the basis for studying slope soil erosion process.The relationship between surface roughness and erosion characteristic parameters in slope erosion process in exposed Pisha sandstone area is studied by field in-situ simulated scour test and terrain factor parameters extracted by ArcGIS.The results showed that:(1)With the increase of scour intensity,the characteristic parameters of resistance decrease gradually,and the characteristic parameters of sediment yield and flow and other hydraulic parameters increase as a whole.With the increase of scouring time,Froude number showed a decreasing trend and other hydraulic parameters showed an increasing trend.The values of Reynolds numbers were all less than 500 under the three scour flow conditions,and the runoff was in laminar flow state.However,when the scour intensity increased,the Froude number showed the law of flow state from slow flow to rapid flow.(2)The change law of surface roughness was not obvious with the increase of scour flow.When the scour intensity was small(<100 L/h),the relationship between surface roughness and sediment yield characteristics was close.(3)Velocity had a significant power function relationship with surface roughness(R2>0.561),which is the optimal parameter reflecting the change of surface roughness.(4)Through Mantel correlation analysis,it was found that with the increase of scour intensity,the change of surface roughness will change from sediment yield characteristics to hydrodynamic parameters characteristics.The results are aimed to reveal the relationship between surface roughness and characteristic parameters of soil erosion process,and provide theoretical basis for the construction of slope soil erosion model in the exposed Pisha sandstone area.