海涂围垦区排灌工程边坡土壤侵蚀过程的水动力学特征  

Hydrodynamic Characters of Runoff in Soil Erosion Processes on Drainage-irrigation Engineering Slope of Farmland in Coastal Region

作　　者：佘冬立[1,2] 刘冬冬[2] 彭世彰[1] 刘营营[2] 

机构地区：[1]河海大学水文水资源与水利工程科学国家重点实验室,南京210098 [2]河海大学水利水电学院,南京210098

出　　处：《水土保持学报》2014年第1期1-5,共5页Journal of Soil and Water Conservation

基　　金：国家自然科学基金项目(51109063);中国博士后科学基金项目(2012T50433)

摘　　要：利用人工模拟降雨试验研究降雨强度和坡度两因子对海涂围垦区排灌工程边坡侵蚀产沙过程及其对径流水动力学参数的响应关系。结果表明，边坡输沙率随降雨历时增加呈S形曲线增长。随雨强和坡度增大，坡面细沟发育迅速，侵蚀量急剧增加，但在坡度25°附近存在一个侵蚀的临界坡度。高雨强和陡坡下，坡面平均流速显著增大，侵蚀输沙率与平均流速之间呈显著线性正相关关系。试验坡面径流雷诺数较小，变化于8．5～42．6之间，水流剪切力为分散边坡土颗粒的主要作用力；坡面输沙率和平均雷诺数之间呈抛物线正相关关系，且在雷诺数较小时坡面输沙率随雷诺数的增长较缓慢，随水流雷诺数的增大，水流紊乱程度越强，坡面产沙能力越强。坡面径流所受阻力系数均随雨强和坡度增大线性降低，输沙率与Manning糙率系数和Darcy Weisbach阻力系数均呈线性负相关关系。Based on simulated rainfall experiment, the dynamic processes of soil erosion and their responded relationships with the runoff-hydraulic parameters for drainage and irrigation engineering slope of farmland in coastal region were studied. The results showed that the erosion rate increased with runoff process under different rainfall intensities and slope gradients, and which could be described with an S-like growth curve equation. With increasing rainfall intensity and slope gradient, the erosion rate increased significantly due to the occurrence and development of the rills during rainfall. There was a critical slope gradient for erosion of the sandy silt soil hillslop, which was about 25°. The average runoff velocity of slope became larger with higher rainfall intensity and steeper slope, and the relationship between the unit sediment yield and the runoff velocity presented a positive linear function. The changes of runoff Reynolds number （Re） for various experimental slopes was located between 8. 5 and 42. 6, kept low level, which meant that the flow shear stress was one of the most important force on dispersion sandy silt soil. The changing tendency of sediment transport rate versus the Re was determined by the increasing type parabola curve, and this increasing rate kept low level when Re was small. With increasing Re, turbulence of runoff became stronger, and so increased erosion rate. The sediment transport rate negatively correlated with the Darcy-Weisbach drag coefficient and Manning roughness coefficient, which linearly ascended with increasing rainfall intensity and slope gradient.

关 键 词：坡面侵蚀 径流流速 流态 水流阻力 

分 类 号：S152.7[农业科学—土壤学]