带状砂沟模式下土壤入渗过程模拟研究

Simulation Investigation of Soil Infiltration Process for Banded Sand Ditches

[目的]探究土壤质地类型和砂沟结构参数对土壤入渗过程的影响,为砂沟集雨工程设计、运行和管理提供科学依据。[方法]基于HYDRUS-2D/3D软件,建立带状砂沟模式下土壤水分运动数学模型,利用室内试验验证模拟带状砂沟模式下土壤入渗过程的可靠性。在此基础上,模拟分析不同影响因素下带状砂沟模式下土壤累积入渗量和湿润锋运移变化过程。[结果]模拟结果与实测数据无显著性差异且一致性良好,表明所建模型及其求解方法能够有效获取带状砂沟模式下不同时刻土壤累积入渗量和湿润锋运移距离数值;均质土壤填充带状砂沟存在明显的增渗效应。原土质地、砂沟距、砂沟宽和砂沟深均对增渗率有较大影响,增渗率随原土饱和导水率和砂沟距的增大而减小,随砂沟宽和砂沟深的增大而增大;土壤湿润锋轮廓呈下低上高的U形,随时间的延长,U形侧边湿润锋逐渐靠近砂沟交汇面,顶部平台逐渐消失;原土质地对湿润锋运移距离影响较大,湿润体随原土饱和导水率的增大而增大;砂沟深对湿润锋的形态和分布影响较大,随砂沟深度的增大,U字体型垂向拉伸,左侧湿润深度显著增大,右侧湿润深度变化微弱;砂土质地、砂沟距和砂沟宽对湿润锋运移距离影响较小。[结论]带状砂沟土体构型能够显著提高土壤入渗能力,土壤质地类型和砂沟结构参数对土壤累积入渗量和湿润锋运移距离均有不同程度影响。

[Objective]The influences of soil texture types and parameters of banded sand ditches on soil infiltration processes were studied in order to provide scientific evidence for the design,operation,and management of sand ditch rainwater harvesting projects.[Methods]HYDRUS-2D/3D software was used to establish a mathematical model for soil water movement in a banded sand ditch,and the reliability of simulating the soil infiltration process in a banded sand ditch model was verified using laboratory experiments.The cumulative infiltration and movement of the wetting front under different influencing factors in a banded sand ditch were simulated and analyzed.[Results]The simulated results were consistent with the measured data.The results showed no significant differences,indicating that the established model and its solution method can effectively produce the numerical values of cumulative soil infiltration and wetting front movement at different times in banded sand ditches.There was a significant increase in infiltration in homogeneous soil filled with banded sand ditches.The original soil texture,sand ditch spacing,sand ditch width and sand ditch depth all significantly impacted infiltration rate.Infiltration rate decreased with an increase in the original soil saturated hydraulic conductivity and sand ditch spacing,but increased with an increase in sand ditch width and depth.The soil-wetting front profile formed a U-shaped pattern with a lower front and a higher back.With time,the U-shaped side-wetting front gradually approached the intersection of the sand ditch,and the top plateau gradually disappeared.The original soil texture significantly impacted the migration distance of the wetting front,which increased with an increase in the original soil saturated hydraulic conductivity.Sand ditch depth significantly impacted the shape and distribution of the wetting front.With an increase in sand ditch depth,the U-shaped pattern stretched vertically,and the wetting depth on the left side increases significantly.The change in wetting depth on the right side was minimal.Sand soil texture,sand ditch spacing,and sand ditch width had relatively minor impacts on the migration distance of the wetting front.[Conclusion]Banded sand ditch structures can significantly improve soil infiltration capacity.Soil texture types and sand ditch structure parameters have different effects on soil cumulative infiltration and wetting front migration distance.