黄土坡面降雨侵蚀养分流失特征及调控措施研究

发布时间：2018-05-14 10:34

本文选题：水土流失 + 凹凸棒土　；参考：《西安理工大学》2017年硕士论文

【摘要】：水土流失是阻碍黄土高原坡地农业发展的重要因素,本文通过野外人工模拟降雨试验,研究不同坡度降雨侵蚀规律及不同调控措施对黄土坡面降雨侵蚀的影响,其结果对黄土高原水土资源的可持续利用具有重要意义。得到以下主要结论:(1)存在临界坡度30°对坡面降雨径流侵蚀产生影响。坡度小于等于30°时,径流侵蚀均随坡度的增加而增大,坡度大于30°时,径流侵蚀随坡度的增加而减小;大雨强下不同坡度单宽流量与产沙率及养分流失率均呈正相关关系,单宽流量与产沙率之间为线性函数关系,单宽流量与养分流失率之间为二次函数关系;水动力学参数与坡度呈正相关关系,单宽流量、产沙率与雷诺数及弗汝德数呈正相关,与阻力系数呈负相关,单宽流量、产沙率与水流剪切力、水流功率、单位水流功率均呈正相关关系;土壤可蚀性指标K1、K3与坡度呈正相关关系,土壤可蚀性指标K2与坡度呈负相关关系。(2)凹凸棒土(ATP)使土壤入渗率、土壤容水度、土壤非饱和扩散率、土壤非饱和传导度减小,使土壤水稳性团聚体和土壤大颗粒含量增加;Philip公式中的吸渗率S和稳渗率A均减小,Kostiakov公式中入渗系数K减小,经验指数β增大;vanGenuchten公式中滞留含水率θr减小,饱和含水率θs增大,进气值的倒数α增大,形状系数n减小;用分形模型模拟饱和导水率及饱和含水率,模拟值与实测值的RMSE在0.1以内;ATP使坡面径流量、产沙量、养分流失量减小,产沙量、养分流失量均随径流量的增加而增加。(3)在两种覆盖格局三种雨强的影响下,碎石嵌入表土时径流量整体较碎石覆盖表土时变化剧烈,碎石覆盖表土时产沙量较碎石嵌入表土变化剧烈,养分流失量在雨强为60mm/h时碎石嵌入表土较碎石覆盖表土变化剧烈,雨强为90、120m/h时碎石覆盖表土较碎石嵌入表土变化剧烈;五种盖度下,产流量随着盖度的增加而增加,产沙量随着盖度的增加而减小,雨强为60mm/h时养分流失量随盖度的增加而减小,雨强为90、120mm/h时养分流失量随盖度的增加而增加;产流量与产沙量在两种碎石格局下均呈负相关,产流量与养分流失量在雨强为60mm/h时呈负相关,在雨强为90、120mm/h时均呈正相关。
[Abstract]:Soil erosion is an important factor that hinders the development of agriculture in sloping land of the Loess Plateau. In this paper, the effects of different slope rainfall erosion laws and regulation measures on rainfall erosion on loess slope surface are studied by artificial rainfall simulation experiment in the field. The results are of great significance to the sustainable utilization of soil and water resources in the Loess Plateau. The main conclusions are as follows: (1) there exists a critical slope of 30 掳which has an effect on the erosion of rainfall runoff on the slope surface. When the slope is less than or equal to 30 掳, the runoff erosion increases with the increase of slope, and when the slope is larger than 30 掳, the runoff erosion decreases with the increase of slope, and the single wide flow rate of different slope is positively correlated with sediment yield and nutrient loss rate under heavy rain. The relationship between single wide flow rate and sediment yield is linear, the relationship between single wide flow rate and nutrient loss rate is quadratic, the hydrodynamic parameters are positively correlated with slope, and the single width flow rate and sediment yield rate are positively correlated with Reynolds number and Froude number. There was a positive correlation between single wide discharge and flow shear force, flow power, unit flow power, soil erodibility index K1K _ 3 and slope, and the soil erosion index K _ (1) K _ (3) was positively correlated with the slope. Soil erodibility index K2 has a negative correlation with slope. (2) attapulgite soil ATP) makes soil infiltration rate, soil moisture content, soil unsaturated diffusion rate and soil unsaturated conductivity decrease. The soil water stable aggregate and soil large particle content were increased. The infiltration rate S and A in the Philip formula were decreased. The infiltration coefficient K was decreased in Kostiakov formula, the residual water content 胃 r and the saturated water content 胃 s in the van Genuchten formula were increased with the increase of the empirical index 尾. The reciprocal 伪 of the inlet air value increases and the shape coefficient n decreases, and the saturated water conductivity and saturated water content are simulated by fractal model. The runoff, sediment yield, nutrient loss and sediment yield of the slope surface are reduced by the RMSE of the simulated value and the measured value within 0. 1. Nutrient loss increased with the increase of runoff. 3) under the influence of two kinds of cover patterns and three kinds of rain intensity, the total runoff of gravel embedded in topsoil changed more sharply than that of crushed stone covering topsoil. The sediment yield of gravel cover topsoil is more dramatic than that of gravel embedded topsoil, the nutrient loss of gravel embedded topsoil is more dramatic when rainfall intensity is 60mm/h, and the change of gravel cover topsoil is more severe when rainfall intensity is 90120m/h. The change of gravel cover topsoil is more severe than that of gravel embedded topsoil when rainfall intensity is 90120m/h. Under five kinds of coverage, the yield of runoff increases with the increase of coverage, the amount of sediment yield decreases with the increase of coverage, the amount of nutrient loss decreases with the increase of coverage when rain intensity is 60mm/h, and increases with the increase of coverage when rain intensity is 90120mm/h. There was a negative correlation between runoff and sediment yield under two gravel patterns, a negative correlation between runoff and nutrient loss when rain intensity was 60mm/h, and a positive correlation between runoff and nutrient loss when rain intensity was 90120mm/h.
【学位授予单位】：西安理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S157.1

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