基于Hydrus-2D的红壤区涌泉根灌自由入渗土壤水分运移数值模拟

Numerical simulation of soil water movement in free infiltration under surge-root irrigation in red soil region based on Hydrus-2D

针对Hydrus-2D软件在红壤区涌泉根灌土壤水分运移模拟的适用性问题,依据非饱和土壤水动力学理论,并结合红壤区涌泉根灌土壤水分运动特征建立了涌泉根灌土壤水分的入渗模型,利用Hydrus-2D软件对模型进行求解,并对湿润锋运移距离以及土壤含水率的模拟值和实测值进行了对比验证。结果表明:在灌水结束时,Hydrus-2D软件对竖直向下方向湿润锋的模拟值和实测值之间相对误差为5.21%,水平方向湿润锋的模拟值和实测值之间相对误差为-7.28%,且湿润锋模拟值和实测值的相关系数(R^2)均大于0.980,RMSE均在1.300 cm以内,F检验P值也均大于0.05;在灌水结束时,距离灌水器不同距离处土壤含水率剖面分布的模拟值和实测值基本一致,均表现为随着土层深度的增加而先增大后减小,在距离灌水器不同位置处,Hydrus-2D软件对剖面土壤含水率的模拟值和实测值之间的相对误差均在±10%以内,且土壤含水率的模拟值和实测值相关系数(R^2)均大于0.990,RMSE在0.030 cm^3·cm^-3以内,F检验P值也均大于0.05。说明模拟值和实测值具有较好的一致性,模拟结果可为红壤区涌泉根灌系统的合理设计及运行提供依据。

Aiming at the applicability of Hydrus-2D software for simulation of soil water movement in surge-root irrigation(SRI)in the red soil region,according to the theory of unsaturated soil hydrodynamics and combining with the characteristics of soil water movement in SRI,the soil water infiltration model was established and solved using the Hydrus-2D software,and the simulated and measured values of the wet front migration distance and soil moisture content(SWC)were compared and verified.The results showed that at the end of irrigation,the relative error between the simulated measured values of the Hydrus-2D software for the vertically downward wet front was 5.21%,and the relative error between the simulated and the measured value of the horizontal wet front was-7.28%,and the correlation coefficients,R2,of the simulated and measured values of the wet front were all greater than 0.980,the RMSE’s were within 1.300 cm,and the P values of the F test were also greater than 0.05.At the end of the irrigation,the SWC at different distances from the emitter between the simulated values and measured values were basically the same,both of which showed that they increased first and then decreased as the depth of the soil layer increased.At different positions from the emitter,The relative errors between the simulated and measured values of SWC were within±10%,and the correlation coefficients,R2,were all greater than 0.990,the RMSE’s were within 0.030 cm^3·cm^-3,and the P values of the F test were also greater than 0.05.The numerical simulation results could provide a theoretical basis for the rational design and operation of the SRI system in the red soil region.