不同降雨特性对坡面产流产沙过程的影响

发布时间：2018-06-02 09:37

本文选题：降雨特性 + 产流　；参考：《浙江大学》2014年博士论文

【摘要】：本研究基于目前土壤侵蚀机理研究存在的不足,利用小尺度人工降雨物理模型、物理概念的分布式水文模型、及统计学方法,以小尺度黄土质坡面为研究对象,整合一系列降雨特性组合展开试验,对黄土地区土壤侵蚀过程中的降雨／产流／侵蚀响应特性进行了剖析和探讨。主要内容如下： (1)基于以往进行的不同降雨特性组合下的坡面降雨产流／土壤侵蚀物理模型比对试验,对详细记录的降雨产流／土壤侵蚀过程中系统内的土壤含水量、地表水流含沙量、水流含沙级配等参数在空间／时间尺度上的变化过程进行了统计分析,认为本研究中小尺度物理模型实验能够较理想地描述水文响应过程。 (2) Integrated Hydrology Model (InHM)能有效模拟产流／土壤侵蚀过程,根据实测数据模拟获得表层土渗透系数值,不仅揭示了降雨过程表层土物理特性的变化规律,也突显了InHM模型相比传统水文模型的优越性。 (3)分析不同降雨特性对坡面产流特性的影响,发现降雨过程中表层土发生显著的结皮现象,降雨特性对结皮结构影响较大,尤其是降雨沿坡面移动方向不同,影响结皮发育类型,进而影响产流阶段特性。结皮发育是土壤孔隙度变小、下渗减少、产流时间提前、产流量增大,产流阶段改变的重要原因。 (4)通过观察侵蚀特征数据,发现随结皮发育及地表径流的持续发生,土壤侵蚀现象显著,各连续降雨过程中土壤侵蚀量普遍逐场递减。移动降雨条件下,总产沙量主要由降雨量和径流发生阶段决定；而峰值产沙量受降雨移动方向影响显著。 (5)侵蚀颗粒粒径分析显示,粉粒泥沙最易被侵蚀,而降雨移动方向对侵蚀成分的影响仅在降雨初期较明显。总体上,降雨任意阶段侵蚀泥沙成分含量(粘粒、粉粒、砂粒)始终保持一种特定的数值比例。 (6)通过分析等效泥沙浓度时空分布特性,发现降雨移动方向和降雨强度对其的影响最关键。且将其作为坡面降雨事件发生极端情况的参考依据,相比传统上仅考虑产流量或侵蚀量,等效泥沙浓度阐释的是单位体积径流的挟沙能力,具有较大工程应用意义。本研究还对土壤侵蚀机理关于等效泥沙浓度的内容进行了完善。 (7)验证了基于软件SPSS(Statistical Package for the Social Sciences)的典型相关分析方法CCA(Canonical Correlation Analysis)对坡面降雨／产流／侵蚀过程机理具有良好的解释性,尤其针对降雨向下移动工况。结果显示坡面响应过程可分解为溅击侵蚀与冲刷侵蚀过程,其主导驱动力分别为降雨强度与降雨量。且各降雨特性因子与坡面响应特性因子之间的关联性均能在分析结果中被较全面的解释。 (8)通过设置坡面上方不同区域的降雨／产流／侵蚀事件,发现降雨离出口处距离不同,对峰值产沙量和产流量相关性,及总产沙量和降雨强度相关性等具有不同程度的影响；同时还造成等效泥沙浓度过程曲线及侵蚀颗粒组分较大差异性。
[Abstract]:Based on the shortcomings of the current research on soil erosion mechanism, this study uses the physical model of small scale artificial rainfall, the distributed hydrological model of physical concepts, and statistical methods, taking the small scale loess slope as the research object and integrating a series of rainfall characteristics combination to carry out the experiment on the rainfall / production in the soil erosion process in the loess region. The characteristics of flow / erosion response are analyzed and discussed. The main contents are as follows:
(1) based on the comparison test of the physical model of rainfall runoff / soil erosion on the slope surface under the combination of different rainfall characteristics in the past, the variation process of soil moisture content in the system, the sediment content in the surface flow and the sediment concentration of the flow in the process of the detailed recorded rainfall runoff / soil erosion process are carried out in the spatial / temporal scale. According to the analysis, it is considered that the small scale physical model experiment can better describe the hydrological response process.
(2) Integrated Hydrology Model (InHM) can effectively simulate the process of runoff and soil erosion. The numerical simulation of surface soil permeability based on the measured data is obtained, which not only reveals the change law of the physical characteristics of the surface soil in the rainfall process, but also highlights the superiority of the InHM model to the traditional hydrological model.
(3) to analyze the influence of different rainfall characteristics on runoff yield characteristics, it is found that there is a significant crust phenomenon in the surface soil during the rainfall process. The rainfall characteristics have great influence on the structure of the crust, especially the different direction of the rainfall along the slope, which affects the development type of the crust, and then affects the characteristics of the runoff generation stage. The crust development is the soil porosity and infiltration. The main reason for the change of runoff generation stage is the reduction of runoff production time and the increase of runoff.
(4) by observing the characteristic data of erosion, it is found that the soil erosion is obvious with the development of the crust and the continuous occurrence of surface runoff. The amount of soil erosion is generally decreasing in the continuous rainfall process. The total sediment yield is mainly determined by the rainfall and the stage of runoff under the condition of moving rainfall, and the peak sediment yield is influenced by the direction of rainfall movement. It is.
(5) the analysis of erosion particle size shows that the silt is most easily eroded, and the influence of the rainfall movement direction on the erosion component is only obvious in the early stage of rainfall. In general, the content of the sediment content (clay, powder and sand) at any stage of rainfall remains a specific numerical ratio.
(6) through the analysis of the spatial and temporal distribution characteristics of the equivalent sediment concentration, it is found that the direction of rainfall movement and the intensity of rainfall are the most important to its influence. And it is considered as the reference basis for the extreme situation of the rainfall event on the slope, compared with the traditional runoff or erosion amount, the equivalent sediment concentration is the capacity to carry the sediment carrying capacity of the unit volume runoff. This study also perfected the content of soil erosion mechanism about equivalent sediment concentration.
(7) verify that the typical correlation analysis method based on software SPSS (Statistical Package for the Social Sciences) CCA (Canonical Correlation Analysis) has a good explanation for the mechanism of rainfall / runoff / erosion process on the slope, especially for the downward movement of rainfall. The results show that the slope response process can be decomposed into splash erosion and erosion. The main driving forces of the erosion erosion process are rainfall intensity and rainfall, and the correlation between the rainfall characteristic factors and the slope response characteristics can be fully explained in the analysis results.
(8) by setting up the rainfall / runoff / erosion events in different areas above the slope, it is found that the distance between the rainfall and the outlet is different, and the correlation of the peak sediment yield and the runoff yield, the correlation of the total sediment yield and the rainfall intensity have different degrees of influence, and the equivalent sediment concentration process curve and the erosion particle component are also large difference. The opposite sex.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：S157;TV12

【参考文献】