模拟微地形空间变异对畦灌系统影响的田间验证

Field verification on simulation of micro-topography spatial variability effect on basin irrigation system

对不同畦块类型和畦灌入流方式,进行了田间灌溉试验。根据田间试验数据,对微地形随机模拟和二维灌溉模型的数值模拟评价方法进行验证。通过随机生成和实测的畦面相对高程模拟所得的畦灌过程和畦灌性能与田间实测结果的对比,得出基于微地形随机模拟和二维灌溉模型对畦灌过程和畦灌性能进行数值模拟具有较好的可行性和实际效果,相比而言,对水流推进时间、平均灌水深度的模拟效果较好;地表水深变化过程、灌溉效率次之;水流消退时间、灌水均匀度稍差。利用基于最小样本容量随机生成的一组畦面相对高程开展微地形空间变异性对畦灌系统影响的数值模拟评价比基于单个典型田块的实测高程数据进行评价更为合理。

The reliability of numerical simulating the micro-topography spatial variability effect on basin irrigation system is verified by field experimental data. Two kinds of micro-topography including the stochastically generated and generated according to measured land surface relative elevation are considered. The 2-D irrigation model is applied to simulate the irrigation process and irrigation performance for different basin shapes and inflow patterns. The comparison shows that the flow advance time and average irrigation water depth of simulation result are in good agreement with field experimental data. The agreement of flow depth variation and irrigation efficiency is slightly less than that of advance time. The agreement of recession time and uniformity of irrigation is the worse. Besides, the simulation result for stochastically generated micro-topography is better than that of generated according to measured land surface relative elevation. Thus, the reliability of utilizing the stochastically generated micro-topography to study the influence of spatial elevation variability on irrigation system by numerical simulation is verified.