中文摘要：

以三种典型红壤为研究对象，采用室内人工模拟降雨方法，研究了湿润速率对坡面径流和侵蚀的影响以及泥沙特性。实验结果表明：在坡度为15°、降雨强度为60mm h^-1条件下，湿润速率越大，产流时间越慢，稳定径流强度越大。供试三种红壤QP1、QP2和QP3快速湿润时稳定径流强度较慢速湿润分别增加60％、37％和21％。同样，坡面侵蚀量也随着湿润速率的增大而增加，供试三种典型红壤在快速湿润条件下侵蚀量较中速湿润分别增加23％、28％和61％，较慢速湿润分别增加112％、85％和159％。侵蚀泥沙的平均质量直径随着湿润速率的增大而减小。研究结果有助于深入理解团聚体破碎机制以及坡面侵蚀机理，为侵蚀模型提供必要的参数。

英文摘要：

The red soil hilly region, located in the tropical and subtropical zones of Southeast China, spreads over 9 provinces and 1 autonomous region. With plentiful light, heat and water resources, it enjoys high potential for agricultural and economic development. However, soil erosion and seasonal drought are major restraints for sustainable agriculture as a result of improper land use and uneven distribution of rainfall. Soil aggregate stability has substantial effects on soil porosity and, therefore, may influence infiltration rate and runoff processes of rainfall. The objects of this study are to determine relationship between wetting rate and runoff and soil loss. Red soils derived from Quaternary red clay were collected and packed in 0.6 m × 0.3 m trays, separately, wetted at 3 wetting rates （2, 10 and 60 mm h^-1）, and then exposed to simulated rainfall with an intensity of 60 mm h^- 1 in laboratory. The Le Bissonnais＇ method was applied to simulating the breakdown mechanisms of slaking in fast wetting, stirred wetting, and slow wetting. The aggregate stability index, i.e. mean mass diameter （MMD）, indicated that fast wetting caused the most severe disruption of aggregates. The MMD in each soil ranked in the order of slow wetting, stirred wetting, fast wetting. Significant correlation was observed between soil loss, runoff rate and wetting rate. The results show that the runoff rate increased with wetting rate, ranging from 0.58 to 0.96 mm min^- 1. In each soil exposed to slow wetting rate, less soil loss was noted. Wetting rate also played a great role in determining sediment materials. The largest MMD of sediment materials was found in soils exposed to fast wetting.