中文摘要：

土壤剥蚀率是单位时间单位面积水流剥蚀土壤的质量，定量研究崩岗不同土层土壤剥蚀率对预测土壤剥蚀过程及建立崩岗侵蚀物理模型具有重要的理论和实践意义。针对湖北通城花岗岩崩岗区发育的表土层、红土层、砂土层、碎屑层，采用不同坡度（8.8%、17.6%、26.8%、36.4%、46.6%）和不同流量（0.2 L s^-1、0.4 L s^-1、0.6 L s^-1、0.8 L s^-1、1.0 L s^-1）相结合的室内放水冲刷试验，分析表土层、红土层、砂土层、碎屑层土体土壤剥蚀率与水动力学参数之间的关系，初步探讨花岗岩崩岗侵蚀的水动力学机制。结果表明：在一定坡度条件下，土壤剥蚀率随径流流量的增大而增大，且各土层土壤剥蚀率存在很大差异，碎屑层土壤剥蚀率最大，砂土层次之，表土层最小；在相同流量条件下，各土层土壤剥蚀率均随冲刷时间的延长逐渐降低并趋于稳定；径流剪切力、水流功率对崩岗各土层土壤剥蚀率的影响均可采用线性方程很好地描述（R2〉0.926），相比用单位水流功率拟合的多项式方程的相关性（R2〈0.830）要高，径流剪切力和水流功率均可作为描述崩岗各土层土壤侵蚀的水动力学参数。表土层、红土层、砂土层、碎屑层的临界径流剪切力依次减小，分别为0.28Pa、0.13Pa、0.10Pa、0.07Pa，各土层土壤细沟可蚀性参数差异明显，碎屑层的最大，砂土层次之，表土层最小。因此，在崩岗垂直结构上，随着土层深度的增加，土体抵抗径流剥蚀的能力逐渐减弱。

英文摘要：

Soil detachment rate refers to the quantity of soil detached by water flow in a unit of time and/or area. Quantitative analyses of the soil detachment processes in different soil layers in granite collapse regions is of great theoretical and practical significance to accurate prediction of soil detachment processes and construction of a physical model for erosion of collapsed hills. 【Method】 Collapsing hill erosion is a speci？c type of soil erosion in hilly granitic regions of tropical and subtropical South China, and may result in extremely rapid water and soil loss. Knowledge of how collapsing hill erosion affects the soil physical and chemical properties of different soil layers in the region is important to understanding the evolution of soil quality. In this study, an in-lab runoff scouring experiment was conducted on artificial slopes of top soil layer, red soil layer, sandy soil layer and detritus layer developed in the collapsed granite hills in Tongcheng, Hubei Province. The runoff scouring experiment had the slopes set at 8.8%, 17.6%, 26.8%, 36.4% and 46.6% in gradient and scoured with flow varying in rate （0.2 L s-1, 0.4 L s-1, 0.6 L s-1, 0.8 L s-1 and 1.0 L s-1）, separately for cross checking . The artificial slope was prepared on a steel trough 0.2m high on both side, 0.2 m wide and 3.8 m long and on the top of the trough was a water tank, 0.2m high, 0.4 m wide and 0.2m long, filled with water to supply water flow steadily at a required rate. The experiment was to investigate relationships of soil detachment rate with various hydrodynamics parameters in four different soil layers and to explore hydrodynamic mechanisms of the erosion in collapsing granite hills. 【Result】 Results show that under the condition of a certain slope, soil detachment rate increased with increasing runoff flow rate, and varied sharply with soil layer; the highest detachment rate was found in the detritus layer, which was followed by sandy soil layer, red soil layer and top soil layer; under the same runoff flow