基于HYDRUS-3D的涌泉根灌土壤入渗数值模拟

Numerical simulation of soil water infiltration under bubbled root irrigation based on HYDRUS-3D

针对涌泉根灌流量大且出流边界为柱状,与传统滴灌、渗灌等存在很大差异的问题,依据非饱和土壤水动力学理论,并结合涌泉根灌条件下土壤水分运动特征,建立了具有柱状出流边界的入渗模型,利用HYDRUS-3D对模型进行求解,所建模型通过土壤剖面含水率随时间变化的实测值与模拟值的对比进行验证.结果表明:模拟值与实测值的相对误差在10%以内,两者具有较好的一致性,数值模拟结果可为涌泉根灌系统的合理设计及运行提供理论依据.通过数值模拟方法研究了流量、套管开孔长度对土壤含水率的影响,发现流量越大,水分运移速率越大,随着时间推移流量所引起的差异减小;灌水量相同时,灌水结束后土壤湿润体范围随流量增大略有减小;开孔区长度增加对湿润体形状、大小没有显著影响,但对土壤湿润体内水分分布状况影响较大.

With large flow and columnar flow boundary,bubbled root irrigation is greatly different from traditional drip irrigation and infiltrating irrigation.It is therefore necessary to study water movement under bubbled root irrigation from different boundaries.Based on the theory of unsaturated soil water dynamics,combining the characteristics of soil water movement under bubbled root irrigation,an infiltration model with columnar flow boundary was established.The HYDRUS-3D software was applied to solve the model numerically.The model is validated through the contrast of measured values and simulated values of the soil moisture which change over time.The results show that the simulation results are in well agreement with measured values.The relative error between simulated and measured values is less than 10%,both of which are quite consistent.The simulation results can provide some theoretical basis for the rational design and operation of the bubbled root irrigation system.The influences on soil moisture content by dripper discharge and drivepipe opening length were studied through numerical simulation method.The results show that the rate of moisture migration increase as dripper discharge increases;the differences caused by dripper discharge decrease over time.With the same water capa-city,the range of soil wetting body slightly decreases as dripper discharge increases.The increases of the opening hole areas have no significant effect on the wetting body shape and size,but it has greater influence on soil moisture distribution.