黄土坡面土壤养分随地表径流流失及动力模型

发布时间：2018-06-01 06:05

本文选题：土壤养分 + 径流泥沙　；参考：《西安理工大学》2016年博士论文

【摘要】：黄土高原地区侵蚀、养分流失现象严重。黄土坡面土壤养分随地表径流迁移是一个复杂的物理化学过程,受到多种因素的影响,准确的预测坡面养分流失量对流域管理、农业耕作指导有重要的意义。本文通过室内试验、野外试验、理论分析相结合的方法,研究降雨特性、土壤特性、地形条件、地表覆盖、施加PAM、施肥方式、地表微地形条件等对坡面养分迁移特征的影响,并提出描述坡面水分、养分传递的数学模型及参数确定方法。主要研究结果如下:(1)坡面径流量、产沙率、养分径流浓度伴随雨强、雨滴动能、坡度、初始含水量、坡长的增加而增加,但是,当坡度为300时,径流量减小;坡面径流量、产沙率、养分径流浓度随碎石覆盖度、PAM施加量的增加而减小;不同土壤质地条件下径流量、钾离子径流浓度大小依次为:杨凌壤土安塞黄绵土神木风沙土;不同施肥方式下钾离子径流浓度大小依次为:表施方式混施方式深施方式;相同糙度条件下微地形表面为半圆形或梯形时,保土保肥效果较好;(2)解析法求解运动波方程,描述两种供水方式下坡面水分运动过程。降雨条件下模型中的参数c与雨强呈幂函数关系变化;上方来水条件下建立了曼宁糙率与碎石覆盖度与覆盖面积之间的函数关系;数值法求解运动波方程验证解析法获取参数的准确性,结果较好,说明提出的近似解析模型可以用于估算入渗参数和曼宁糙率以及坡面水动力特征参数;(3)有效混合深度模型、等效混合深度模型均可用于预测坡面养分流失过程及流失量,不完全混合深度模型拟合效果比完全混合深度模型好,完全混合深度模型由于简单的参数,便于推广使用;混合层深度与各影响因子的乘积呈线性关系变化;(4)提出了降雨侵蚀作用下的养分传递模型及相关参数的确定方法,并建立了混合层深度与雨强、时间之间的函数关系,模型获得的参数m只与养分类型有关,k可以表示为雨强、坡度、养分类型的函数。(5)提出了水流冲刷条件下养分向地表径流传递模型及相关参数的确定方法,建立了混合层深度与水深、时间函数关系,实测资料验证模型结果显示拟合的钾离子径流浓度、径流流失量随时间的变化过程效果较好,参数ke与Re呈线性关系变化。
[Abstract]:The phenomenon of nutrient loss is serious in Loess Plateau. Soil nutrient migration with surface runoff is a complex physical and chemical process, which is influenced by many factors. Accurate prediction of soil nutrient loss is of great significance for watershed management and agricultural guidance. In this paper, the effects of rainfall characteristics, soil characteristics, topographic conditions, surface mulching, application of PAM, fertilization methods and surface microtopography conditions on nutrient transport characteristics of slope surface were studied by means of laboratory test, field test and theoretical analysis. A mathematical model and a method for determining the parameters of water and nutrient transfer on slope are proposed. The main results are as follows: (1) runoff, sediment yield, nutrient runoff concentration increase with the increase of rain intensity, raindrop kinetic energy, slope, initial water content and slope length. However, when the slope is 300, the runoff decreases. The sediment yield and nutrient runoff concentration decreased with the increase of the amount of gravel coverage and PAM, and the runoff concentration of potassium ions in different soil texture was: Yang Ling loam, Ansai loess, Shenmu sandy soil; The order of K ~ + runoff concentration under different fertilization conditions was as follows: surface application mode, deep application mode, and soil conservation with semicircle or trapezoid surface under the same roughness, the analytical method was used to solve the motion wave equation, and the equation of motion wave was solved by the analytical method, and the effect of soil conservation was better when the surface of the soil was semicircular or trapezoid. This paper describes the process of water movement on slope under two water supply modes. The relationship between the parameters c and rain intensity is power function under rainfall condition, and the relationship between Manning roughness and gravel coverage and coverage area is established under the condition of upper water coming. Numerical solution of motion wave equation verifies the accuracy of the analytical method and the results are good. The proposed approximate analytical model can be used to estimate the infiltration parameters, Manning roughness and hydrodynamic parameters of slope. The equivalent mixing depth model can be used to predict nutrient loss process and loss on slope surface. The fitting effect of incomplete mixing depth model is better than that of complete mixing depth model. Because of simple parameters, complete mixing depth model is easy to be popularized and used. A linear relationship between the mixing layer depth and the product of each influencing factor is presented. (4) the nutrient transfer model under rainfall erosion and the method of determining the relative parameters are proposed, and the functional relationship between the mixing layer depth and rain intensity and time is established. The parameter m obtained by the model can only be expressed as the function of rain intensity, slope and nutrient type. The model of nutrient transfer to surface runoff under the condition of water flow erosion and the determination of related parameters are proposed. The relationship between mixing layer depth and water depth and time function was established. The measured data showed that the fitted potassium ion runoff concentration and runoff loss with time had a good effect, and the parameter ke had a linear relationship with re.
【学位授予单位】：西安理工大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S157.1

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