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花岗岩崩岗区不同土层的侵蚀水动力学特征
引用本文:王秋霞,丁树文,邓羽松,刘丹露,徐加盼,朱慧鑫,刘昌鑫.花岗岩崩岗区不同土层的侵蚀水动力学特征[J].土壤学报,2017,54(3):570-580.
作者姓名:王秋霞  丁树文  邓羽松  刘丹露  徐加盼  朱慧鑫  刘昌鑫
作者单位:1. 华中农业大学资源与环境学院,武汉,430070;2. 华中农业大学资源与环境学院,武汉 430070;农业部长江中下游耕地保育重点实验室,武汉 430070
基金项目:国家自然科学基金项目(41571258)
摘    要:土壤剥蚀率是单位时间单位面积水流剥蚀土壤的质量,定量研究崩岗不同土层土壤剥蚀率对预测土壤剥蚀过程及建立崩岗侵蚀物理模型具有重要的理论和实践意义。针对湖北通城花岗岩崩岗区发育的表土层、红土层、砂土层、碎屑层,采用不同坡度(8.8%、17.6%、26.8%、36.4%、46.6%)和不同流量(0.2 Ls~(-1)、0.4 Ls~(-1)、0.6 Ls~(-1)、0.8 Ls~(-1)、1.0 Ls~(-1))相结合的室内放水冲刷试验,分析表土层、红土层、砂土层、碎屑层土体土壤剥蚀率与水动力学参数之间的关系,初步探讨花岗岩崩岗侵蚀的水动力学机制。结果表明:在一定坡度条件下,土壤剥蚀率随径流流量的增大而增大,且各土层土壤剥蚀率存在很大差异,碎屑层土壤剥蚀率最大,砂土层次之,表土层最小;在相同流量条件下,各土层土壤剥蚀率均随冲刷时间的延长逐渐降低并趋于稳定;径流剪切力、水流功率对崩岗各土层土壤剥蚀率的影响均可采用线性方程很好地描述(R~20.926),相比用单位水流功率拟合的多项式方程的相关性(R0.830)要高,径流剪切力和水流功率均可作为描述崩岗各土层土壤侵蚀的水动力学参数。表土层、红土层、砂土层、碎屑层的临界径流剪切力依次减小,分别为0.28Pa、0.13Pa、0.10Pa、0.07Pa,各土层土壤细沟可蚀性参数差异明显,碎屑层的最大,砂土层次之,表土层最小。因此,在崩岗垂直结构上,随着土层深度的增加,土体抵抗径流剥蚀的能力逐渐减弱。

关 键 词:崩岗  土壤剥蚀率  放水冲刷试验  水动力学参数
收稿时间:2016/6/24 0:00:00
修稿时间:2016/9/28 0:00:00

Hydrodynamic Characteristics of Erosion in Different Soil Layers in Granite Collapse Region
WANG Qiuxi,DING Shuwen,DENG Yusong,LIU Danlu,XU Jiapan,ZHU Huixin and LIU Changxin.Hydrodynamic Characteristics of Erosion in Different Soil Layers in Granite Collapse Region[J].Acta Pedologica Sinica,2017,54(3):570-580.
Authors:WANG Qiuxi  DING Shuwen  DENG Yusong  LIU Danlu  XU Jiapan  ZHU Huixin and LIU Changxin
Affiliation:huazhongnongyedaxue,huazhongnongyedaxue
Abstract:Objective]Soil detachment rate refers to the quantity of soil detached by water flow in a unit of time and/or area. Quantitative analyses of the soil detachment processes in different soil layers in granite collapse regions is of great theoretical and practical significance to accurate prediction of soil detachment processes and construction of a physical model for erosion of collapsed hills. Method]Collapsing hill erosion is a specific type of soil erosion in hilly granitic regions of tropical and subtropical South China,and may result in extremely rapid water and soil loss. Knowledge of how collapsing hill erosion affects the soil physical and chemical properties of different soil layers in the region is important to understanding the evolution of soil quality. In this study,an in-lab runoff scouring experiment was conducted on artificial slopes of top soil layer,red soil layer,sandy soil layer and detritus layer developed in the collapsed granite hills in Tongcheng,Hubei Province. The runoff scouring experiment had the slopes set at 8.8%,17.6%,26.8%,36.4% and 46.6% in gradient and scoured with flow varying in rate(0.2 L s-1, 0.4 L s-1,0.6 L s-1,0.8 L s-1 and 1.0 L s-1),separately for cross checking . The artificial slope was prepared on a steel trough 0.2 m high on both side,0.2 m wide and 3.8 m long and on the top of the trough was a water tank,0.2 m high,0.4 m wide and 0.2m long,filled with water to supply water flow steadily at a required rate. The experiment was to investigate relationships of soil detachment rate with various hydrodynamics parameters in four different soil layers and to explore hydrodynamic mechanisms of the erosion in collapsing granite hills. Result] Results show that under the condition of a certain slope,soil detachment rate increased with increasing runoff flow rate,and varied sharply with soil layer;the highest detachment rate was found in the detritus layer,which was followed by sandy soil layer,red soil layer and top soil layer;under the same runoff flow rate,soil detachment rate decreased with the scouring going on and tended to level off,regardless of type of soil layers. Besides,the complex effect of slope degree and flow rate on detachment rates in all soil layers could be well fitted with the two-variable power function equation (R2>0.878). The effects of shear stress and stream power of the runoff on detachment rate on all soil layers could be well described with the linear equation(R2>0.926),yielding a correlation coefficient much higher than that of the fitting of unit stream power with the polynomial equation(R2<0.830). Therefore,shear stress and stream power of the runoff can be used as hydrodynamic parameters to describe the soil erosion in different soil layers of collapsed hills. The threshold of runoff shear stress varied with soil layer in a decreasing order of top soil layer>red soil layer>sandy soil layer>detritus layer or 0.28 Pa>0.13 Pa>0.10 Pa>0.07 Pa. Conclusion] The detritus layer is the highest in erodibility,followed by the sandy soil layer,red soil layer and top soil layer. Hence,the resistance of the soil layers against runoff erosion gradually decreases with soil depth as the soil layers exist vertically in the soil profile in the collapsing hill region.
Keywords:Collapsed gully  Soil detachment rate  Runoff scouring experiments  Hydrodynamics parameters
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