土壤水分条件对鄂南红壤可蚀性及坡面侵蚀的影响
发布时间：2019-01-30 08:14
【摘要】：水分在土壤侵蚀过程中扮演着重要的角色。土壤侵蚀过程通常认为是水的侵蚀性与土壤可蚀性之间的相互作用,侵蚀性和可蚀性是理解和预测土壤侵蚀的基石。土壤水分条件有多种表现形式,包括土壤含水量、水分运动、水力梯度等,大量研究指出土壤水分条件影响土壤侵蚀,但多数土壤侵蚀预测模型并没有调整相关的土壤侵蚀参数。因此,进一步研究土壤水分条件对土壤侵蚀的影响十分必要,以便改进现有的土壤侵蚀模型。本文以湖北南部三种母质(第四纪红色粘土、花岗岩、泥质页岩)发育的红壤为研究对象,基于WEPP模型理论,分别研究土壤水分条件对细沟侵蚀过程和细沟间侵蚀过程的影响,所得到的主要结论如下:(1)对于细沟可蚀性而言,土壤水分条件是存在影响的,风干条件下的细沟可蚀性值显著高于饱和和排水条件,而后两者之间的差异并不显著。由风干到排水再到饱和的过程中,即模拟自然坡面上土壤由干燥而湿润进而出现渗流的过程,前期土壤含水量较低时极细砂含量、粘粒含量对于细沟可蚀性的影响力都是显著的,粘粒含量的影响力虽然在初期较大,但这种影响力逐渐衰减,至渗流出现时已不产生显著影响;极细砂含量则自始至终发挥着重要作用。这也意味着土壤水分条件难以撼动极细砂含量对细沟可蚀性的影响。第四纪粘土母质发育的红壤在风干条件下的值明显高于公式预测值,花岗岩母质发育的红壤则偏低。(2)对于临界剪切力而言,不同的水分条件下测定的值是不同的,风干条件下的最小,显著低于饱和和排水条件下的均值。风干和排水条件下砂粒含量所起的作用高于其它土壤性质,而饱和条件时粘粒的增加有助于提高临界剪切力。(3)土壤水分条件对侵蚀过程趋向稳定时的产流量和含沙量影响较大,而对于泥沙的粒径分布则主要在径流刚产生时发生影响。(4)对于细沟间可蚀性而言,在饱和(即渗流)条件下,其值大幅增长;排水和风干条件下的细沟间可蚀性差异不明显,即使前者略高于后者。当土壤水分条件为风干时有0.25mm水稳性团聚体含量(%)一个土壤性质与细沟间可蚀性显著相关;排水时的有砂粒含量、极细砂含量和粉粒含量3个;饱和时无一存在相关性,仅粉粒含量(g/kg)影响徘徊在显著性边缘(P=0.053)。实测值普遍大于公式预测值,特别是在“泥质页岩-饱和”条件下,前者超过后者5倍。(5)土壤水分条件对细沟间可蚀性的影响显著大于细沟可蚀性,尤其是当渗流出现时。
[Abstract]:Water plays an important role in soil erosion. The process of soil erosion is generally regarded as the interaction between water erosion and soil erodibility, which is the cornerstone of understanding and predicting soil erosion. Soil moisture conditions have many forms, including soil water content, water movement, hydraulic gradient and so on. A large number of studies have pointed out that soil moisture conditions affect soil erosion. However, most soil erosion prediction models do not adjust the soil erosion parameters. Therefore, it is necessary to further study the influence of soil moisture on soil erosion in order to improve the existing soil erosion models. Based on the theory of WEPP model, the effects of soil moisture conditions on the process of rill erosion and inter-gully erosion were studied based on the red soil developed by three parent materials (Quaternary red clay, granite, shales) in southern Hubei Province, based on the theory of WEPP model. The main conclusions are as follows: (1) for the erodibility of the rill, the soil moisture condition is affected, the erodibility of the soil under the air-dry condition is significantly higher than that of the saturation and drainage conditions, but the difference between the latter two is not significant. The process from air drying to drainage to saturation is to simulate the process of soil wetting and percolation on the natural slope, and the very fine sand content in the early stage when the soil moisture content is low. The influence of the clay content on the erodibility of the rill is significant, although the influence of the clay content is great in the initial stage, but the influence gradually decreases, until the seepage appears, it has no significant effect. The content of very fine sand plays an important role from beginning to end. This also means that the soil moisture condition can not shake the effect of very fine sand content on the erodibility of the rill. The value of red soil developed in Quaternary clay is obviously higher than the predicted value of formula under the condition of air drying, while the red soil developed by granitic material is lower. (2) for critical shear stress, the values measured under different water conditions are different. The minimum value under air drying condition is significantly lower than the average value under saturated and drainage conditions. The effect of sand content on air drying and drainage is higher than other soil properties. But the increase of clay in saturated condition can increase the critical shear stress. (3) soil moisture condition has a great influence on the yield and sediment content when the erosion process tends to be stable. The particle size distribution of sediment is mainly affected when runoff is first produced. (4) for the erodibility of the gully, the value increases greatly under the condition of saturation (i.e. seepage); There was no significant difference in erodibility between drains and drains, even though the former was slightly higher than the latter. The content of 0.25mm water stable aggregates (%) was significantly correlated with the erodibility of the rill when the soil moisture condition was air-dried, the sand content, the ultrafine sand content and the silt content were 3 in drainage. There was no correlation during saturation, but only the effect of powder content (g/kg) hovered at the significant edge (P0. 053). The measured values are generally greater than the predicted values of the formula, especially under the condition of shale-saturation, the former is 5 times greater than the latter. (5) the effect of soil moisture on the erodibility of the rill is significantly greater than that of the erodibility of the rill. Especially when seepage occurs.
【学位授予单位】：华中农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S157
本文编号：2417932
[Abstract]:Water plays an important role in soil erosion. The process of soil erosion is generally regarded as the interaction between water erosion and soil erodibility, which is the cornerstone of understanding and predicting soil erosion. Soil moisture conditions have many forms, including soil water content, water movement, hydraulic gradient and so on. A large number of studies have pointed out that soil moisture conditions affect soil erosion. However, most soil erosion prediction models do not adjust the soil erosion parameters. Therefore, it is necessary to further study the influence of soil moisture on soil erosion in order to improve the existing soil erosion models. Based on the theory of WEPP model, the effects of soil moisture conditions on the process of rill erosion and inter-gully erosion were studied based on the red soil developed by three parent materials (Quaternary red clay, granite, shales) in southern Hubei Province, based on the theory of WEPP model. The main conclusions are as follows: (1) for the erodibility of the rill, the soil moisture condition is affected, the erodibility of the soil under the air-dry condition is significantly higher than that of the saturation and drainage conditions, but the difference between the latter two is not significant. The process from air drying to drainage to saturation is to simulate the process of soil wetting and percolation on the natural slope, and the very fine sand content in the early stage when the soil moisture content is low. The influence of the clay content on the erodibility of the rill is significant, although the influence of the clay content is great in the initial stage, but the influence gradually decreases, until the seepage appears, it has no significant effect. The content of very fine sand plays an important role from beginning to end. This also means that the soil moisture condition can not shake the effect of very fine sand content on the erodibility of the rill. The value of red soil developed in Quaternary clay is obviously higher than the predicted value of formula under the condition of air drying, while the red soil developed by granitic material is lower. (2) for critical shear stress, the values measured under different water conditions are different. The minimum value under air drying condition is significantly lower than the average value under saturated and drainage conditions. The effect of sand content on air drying and drainage is higher than other soil properties. But the increase of clay in saturated condition can increase the critical shear stress. (3) soil moisture condition has a great influence on the yield and sediment content when the erosion process tends to be stable. The particle size distribution of sediment is mainly affected when runoff is first produced. (4) for the erodibility of the gully, the value increases greatly under the condition of saturation (i.e. seepage); There was no significant difference in erodibility between drains and drains, even though the former was slightly higher than the latter. The content of 0.25mm water stable aggregates (%) was significantly correlated with the erodibility of the rill when the soil moisture condition was air-dried, the sand content, the ultrafine sand content and the silt content were 3 in drainage. There was no correlation during saturation, but only the effect of powder content (g/kg) hovered at the significant edge (P0. 053). The measured values are generally greater than the predicted values of the formula, especially under the condition of shale-saturation, the former is 5 times greater than the latter. (5) the effect of soil moisture on the erodibility of the rill is significantly greater than that of the erodibility of the rill. Especially when seepage occurs.
【学位授予单位】：华中农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S157
【参考文献】
相关期刊论文 前1条
1 王辉;王全九;邵明安;;前期土壤含水量对黄土坡面氮磷流失的影响及最优含水量的确定[J];环境科学学报;2008年08期
，本文编号：2417932
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