黄土区坡地浅沟侵蚀剥蚀输沙互馈机制及模型参数的系统确定

Ephemeral gullies are defined as small channels eroded by concentrated flow that can be easily filled by normal tillage, only to reform again in the same location by additional runoff events. They can be a major sediment source and are the main conduits that convey runoff and sediment from most farm fields. On the slope farmland, esp. in hilly areas of the Loess Plateau, ephemeral gullies are the transitional links between rills and classical gullies, contributing to 35% -70% of the slope area, intensified the concentrated flow on the slope land. Ephemeral gully erosion is not estimated with RUSLE, which can result in major errors in estimates of sediment yield leaving farm fields. Much deposition can occur in concentrated flow areas resulting in sediment load leaving a farm field being much less than the sediment produced by rill-interrill and ephemeral gully erosion within the field. Water erosion prediction project based on the processes, taking into account the spatial distribution of sediment and the evolution of hydrological processes, could calculate the ephemeral gully erosion. However, uncertainties of parameters estimation for model may affect the results. Most current studies on ehemeral gully erosion use spatially-averaged soil erosion data, providing little information on soil erosion dynamics. The mechanisms involved in ephemeral gully erosion are very important in developing and improving process-based erosion prediction models.Based on the sediment continuity equation and a sophisticated finite element model for rill erosion developed by our research team, we will develop the flume experiments for ephemeral gully erosion process. Objectives of this project are: (1) to develop a exerimental method to obtain the processed-based spacial and temperial data for ephemeral gully erosion; (2)to make clear the effects of the hydro parameters on ehmeral gully development,and to establish the feedback relationship between the detachment and transport capacity during the ephemeral gully evolvement; (3)to develop a systematic experimental method and relatd algorithm to determine the soil detachment, transport capacity, soil erodibility and critical soil shear shtress for ephemeral gully erosion.

浅沟是黄土区坡地侵蚀产沙的主要来源和输沙通道，构建以物理过程为基础的侵蚀预报模型是目前的研究热点和难点，然而侵蚀过程中剥蚀输沙互馈机制不清楚、模型参数确定困难增加了模型误差。拟以黄土区坡地典型浅沟侵蚀为研究对象，抓住影响浅沟侵蚀的主要动力因子，运用沟道侵蚀动力学原理，从改进浅沟侵蚀过程研究的土槽试验方法入手，融合沿全沟长不同沟段实时测量法和侵蚀后回填测量法，获取浅沟水流含沙量沿全沟长时空分布数据；确定水沙耦合作用下浅沟水流的水动力参数和水动力学特征，揭示浅沟水流剪切力作用下土壤颗粒由地表剥离输移的动力学机制及剥蚀输移的互馈关系；以质量守恒和泥沙连续方程为基础，借助数学推导方法，以当浅沟水流携带含沙量达到饱和时的输沙能力为突破口，提出模型中输沙能力、剥蚀率、土壤可蚀性参数、临界剪切力等关键参数的系统确定方法，研究结果可为预报模型向完整物理模型转化和全方位验证提供理论依据和新的途径。

浅沟是坡耕地侵蚀产沙的主要来源和输沙通道，然而侵蚀过程中剥蚀输沙互馈机制不清楚、模型参数确定困难增加了模型误差。该基金以坡地典型浅沟侵蚀为研究对象，运用沟道侵蚀动力学原理，从改进浅沟侵蚀过程研究的土槽试验方法入手，融合沿全沟长不同沟段实时测量法和侵蚀后回填测量法，获取浅沟水流含沙量沿全沟长时空分布数据；确定水沙耦合作用下浅沟水流的水动力参数和水动力学特征，揭示浅沟水流剪切力作用下土壤颗粒由地表剥离输移的动力学机制及剥蚀输移的互馈关系；以质量守恒和泥沙连续方程为基础，借助数学推导方法，以当浅沟水流携带含沙量达到饱和时的输沙能力为突破口，提出模型中输沙能力、剥蚀能力和剥蚀速率的试验方法和定量确定方法，研究结果可为预报模型向完整物理模型转化和全方位验证提供理论依据和新的途径。在该基金资助下在土壤侵蚀过程及迁移速率的计算方法有突破性进展，发表SCI论文7篇，在审SCI论文1篇；获授权发明专利1项，申请发明专利5项（均为实审阶段），获软件著作权4项。