水力侵蚀比尺模型试验是研究小流域水土流失规律、水土保持治理措施优化及调控效益的有效方法。依据已有的基于侵蚀泥沙动力学和相似论基本原理给出的黄土高原小流域水力侵蚀调控模拟及结果转换控制指标系统建造的黄土高原燕沟康家圪崂小流域水力侵蚀比尺模型，仅对模型与原型的径流总量、侵蚀总量、侵蚀淤积级配等指标进行了初步验证，更深入的验证工作包括小流域不同位置坡面径流的流速、流向、流场分布、阻力相似问题以及侵蚀过程相似等需要进一步研究。本研究针对黄土高原小流域水力侵蚀比尺模型存在的选沙及验证试验问题，利用黄土高原小流域水力侵蚀调控实体模拟试验理论与技术，在室内设计了几何比尺为2.5的10°原型和模型坡面，对黄土坡面水力侵蚀比尺模拟试验径流及侵蚀过程的相似性进行研究，得到以下结论：

1．黄土坡面水力侵蚀比尺模拟试验宜用起动相似为主的选沙方法选择模型沙。本研究试验条件下，利用悬浮相似为主的选沙方法选择的模型沙需要检验模型沙是否满足起动相似，利用满足悬浮相似但不满足起动相似的模型沙进行试验，侵蚀方式、侵蚀地形和侵蚀过程相似都较难满足；由于依据起动相似为主的选沙方法选择的模型沙大部分粒径小于0.1mm，在这个粒径范围内，起动流速随着粒径的减小而增大，模型沙粒径较原型沙粗，但在雨强等边界条件相似的前提下，原型和模型试验的流量和侵蚀过程基本相似。

2．黄土坡面水力侵蚀比尺模拟试验径流及侵蚀过程相似验证结果表明：本研究试验条件下，原型和模型的径流流态均为急流；120mm/h和100mm/h雨强组试验原型和模型的径流流型不同，原型坡面径流的流型为过渡流，而模型坡面的径流流型则为层流，80mm/h雨强组试验原型和模型坡面的径流流型均为层流；原型和模型的阻力相似比尺有偏离但基本满足λs_f≈1，表明在坡面径流是急流条件下，虽然满足Fr相似是保证流态相似的主要方面，但阻力相似偏离不大，基本满足相似要求；在降雨、入渗、土壤前期含水量等边界条件相似的前提下，原型和模型的流量过程、断面平均流速、径流深等基本相似，原型和模型的径流过程基本满足相似要求；在径流过程相似的前提下，满足起动相似的原型和模型试验的侵蚀产沙过程、冲淤级配及地形也基本相似。

上述情况表明，在正态条件下，满足几何相似、降雨相似、水力侵蚀产沙、输沙及入渗相似等条件下所建造的坡面模型，其降雨、汇流、产沙、输沙是基本符合原型实际情况的，可以作为坡面治理水土流失、优化治理方案，寻求水土资源高效利用措施的工具。

1. It would be better to use the method based on the incipient motion similarity rule in selecting the model material in the hydraulic erosion simulation experiment on the loess slope. The runoff processes basically met the requirement of similarity as long as the boundary conditions, including that rainfall intensity metλ_i=λ^1/2₁and soil water content metλ_θ=1, were similar; Model material selected based on the suspension similitude rule should be verified whether it could meet the requirement of incipient motion similarity, if it couldn’t meet the requirement of incipient motion similarity, it also couldn’t meet the similarity of erosion processes; Model material selected based on the incipient motion similarity rule could basically meet the requirement of erosion processes similarity to some extent.

2. The verifying experiments results showed: within the range of slope and rainy intensity designed in the experiments, both of its flow state appeared to be supercritical flow for the prototype and model under the rainfall intensity groups of 120mm/h, 100mm/h and 80mm/h, however, flow patterns were different under the rainfall intensity groups of 120mm/h and 100mm/h, showing as transition flow of the prototype and laminar flow of the model while the flow of prototype and model were both laminar flow under the rainy intensity group of 80mm/h. Meanwhile, as forλs_f≈1, similarity of flow resistance was basically meet. The flow rate processes, flow velocity and runoff depth etc. could basically meet the requirement of similarity as long as boundary conditions, including that rainfall intensity and soil moisture etc., were similar. The erosion processes would be basically similar too as long as the flow processes were basically similar. Consequently, the sediment yield amount in model experiment could basically be transferred to antetype.

Under the normal conditions, such sloping models with scale of 2.5 were built complying with the similarities of geometric, rainfall, flow, erosion production and sediment transport etc., and the verifying experiments results indicated that the movement of rainfall, flow, sediment production of the model experiment could agree with the practical situation of the antetype experiment. So it can be applied as a tool in controlling soil erosion, optimizing regulating measures and utilizing water and soil resource efficiently.