基于矩分析的垄沟灌入渗湿润体特征

Wetting Pattern of Ridge-furrow Irrigation Infiltration Described with Moment Analysis

为指导垄沟灌溉技术参数的合理设计,利用验证的HYDRUS-2D模型模拟不同土壤物理性质、耕作技术参数和灌水技术参数组合的垄沟灌土壤水分入渗过程,采用空间矩分析方法定量分析不同因素对入渗湿润体特征量及椭圆特征值的影响。结果表明:矩分析垄沟灌溉入渗湿润体呈扁平椭圆状;初始含水量对湿润体特征量的影响较其它因素小;垄沟灌溉宜在质地重的土壤条件下应用;随沟底宽度和灌溉水深增大,椭圆面积亦增大,椭圆长短轴差异明显,显著加大水平侧渗距离,砂壤土宜窄沟种植,黏壤土宜宽沟灌溉种植,较高的灌溉水深可增加侧渗,有利于提高灌水均匀度。空间矩分析为研究土壤水空间分布特征提供了一种强有力数学方法。

In order to provide guidance to reasonable design of technique parameters in ridge-furrow irrigation,the migration laws of wetting pattern were investigated.Soil water infiltration affected by soil physical properties,cultivation technique parameters,and irrigation technique parameters under ridge-furrow irrigation was numerically simulated by using the HYDRUS-2D model.The effect of variables on wetting patterns and ellipse characteristics were quantitatively evaluated by using moment analysis.The result showed that the wetting pattern was like an ellipse with a long axis in the horizontal direction.Initial soil water content had a minor effect on ellipse characteristics compared with other variables.The ridge-furrow irrigation technique should be implemented in finer soils.With the increase of furrow width and irrigation water depth,the elliptical area is increasing and the discrepancy of elliptical axis length is obvious,which significantly increase the lateral infiltration distance.We should select narrow furrows for sandy loam and wide furrows for clay loam.Spatial moment analysis allows a straightforward,physically meaningful description of the wetting pattern for subsurface water distribution.