基于HYDRUS-3D模型的微润灌溉土壤水分入渗模拟

掌握土壤水分入渗规律对于合理制定灌溉方案、设置灌溉参数和改进灌溉技术有重要意义。为探究微润灌溉条件下土壤水分入渗规律,利用HYDRUS-3D有限元模型对微润灌溉下土壤水分入渗进行了数值模拟,讨论了初始压力水头和土壤质地对土壤水分入渗的影响。数值模拟结果显示：在土壤水分入渗的垂直剖面上湿润体以微润管为中心呈同心圆状向外扩散,扩散速率与初始压力水头呈正相关。模拟试验周期为36h,分3个时间段进行土壤水分扩散速率的计算,0~5h内土壤水分平均入渗速率为1.85cm/h,6~15h内的平均入渗速率为0.79cm/h,16~36h内的平均水分入渗速率为0.59cm/h。土壤含水率最大值出现在微润管周围,向外围呈减小趋势。相同时间内土壤湿润峰运移距离随初始压力水头的增大而增大,微润灌溉下水分入渗速率在3种质地的土壤（砂壤土、壤土、粘壤土）中依次增大,并测得在压力水头为-180cm时整个模拟周期中3种质地土壤的平均水分扩散速率分别为：0.69、0.53、0.46cm/h。研究表明,土壤含水率和水分扩散速率随压力水头的增大而增大,随土壤黏粒含量的增大而减小。

Numerical Simulation of Soil Water Infiltration Based on HYDRUS-3D Finite Element Model under Moistube-irrigation

It is important to master the law of soil water infiltration for the rational development of irrigation scheme, setting irrigation parameters and improving irrigation technology. In order to explore the law of soil water infiltration under the condition of moistube-irrigation, HYDRUS-3D finite element model was used to simulate the soil water infiltration under micro-irrigation. The effects of initial pressure head and soil texture on soil water infiltration were discussed. The numerical simulation results showed that the wetting body was diffused around the micro-tube in the vertical section of soil water infiltration, and the diffusion rate was positively correlated with the initial pressure head. The average infiltration rate of soil water was 1.85cm/h in the first 5 hours, the average infiltration rate was 0.79cm/h between the 6th hour to 15th hour, and the average water infiltration rate in the period from 16th hour to 36th hour was 0.59cm/h. The maximum soil moisture content appeared around the micro fabricated tube and tended to decrease to the periphery. The migration distance of soil wetting peak increased with the increase of initial pressure head. The infiltration rate of micro-irrigation increased in three soil layers (sandy loam, loam, loam loam). When the pressure head was -180cm, the average water diffusion rates of the three soils were 0.69cm/h, 0.53cm/h and 0.46cm/h, respectively.