初始含水率对涌泉根灌土壤渗透特征的影响

为探索初始土壤含水率对涌泉根灌过程中湿润锋运移和土壤水分分布的影响,合理确定灌水技术参数,配置了5种不同初始土壤含水率,采用室内土箱模拟试验方法,研究了土壤初始含水率对涌泉根灌均质土壤水分扩散的影响.结果表明：涌泉根灌条件下,初始含水率对湿润体形状的影响不大,对其大小有明显影响;土壤表面湿润时间与初始含水率呈递减关系,土壤表面湿润半径、湿润体水平与垂直距离的增长速度均随着土壤初始含水率的增大而增大;土壤初始含水率越大湿润体内水分分布越均匀;试验拟合的根据土壤初始含水率计算地表湿润半径、最大湿润体水平半径与垂直深度的经验公式,计算值和实测值之间误差较小,整体误差分别为0.63%,0.4%,0.83%和0.59%,0.12%,0.73%,可用经验公式推算涌泉根灌土壤水分渗透参数,作为涌泉根灌系统设计依据.

Effect of initial water content on soil infiltration characteristics during bubble irrigation

The effects of initial water content in soil on the soil moisture distribution during bubble irri- gation were investigated using repacked soil boxes. Five initial soil Moisture content were tested. The results showed that the initial soil moisture content has less influence on the shape of soil wetted volume but quite large on the volume sizes under the condition of bubbled-root irrigation. The time needed to wet soil surface was reduced and the expansion of the wetting front became fast horizontally and verti- cally with increasing initial soil moisture content. The higher the initial moisture content, the more uni- form the distribution of soil moisture in a wetted soil volume. Empirical equations were fitted with the experimental data to estimate the surface wetted radius, maximum horizontal wetted radius and vertical wetted depth. The IRE and the RMSE between prediction and observation were 0.63% , 0.4% , 0.83% and 0.59% , 0.12% , 0.73% , respectively, suggesting the empirical equations are applicable for estimate of soil water infiltration parameters in bubble irrigation.