壤中滴灌条件下植被混凝土水分运移规律

以复合人造土壤为研究对象,研究滴头流量、坡度因子对植被混凝土水分运移过程的影响效应,揭示壤中滴灌条件下植被混凝土湿润锋运移动态变化及含水率时空分布特征,探讨植被混凝土与天然土壤在水分运移方面的异同,为高陡边坡生态恢复下壤中滴灌系统的灌溉布局与灌溉制度提供理论参考。结果表明:滴头流量、坡度对垂直向上方向的水分运移影响最大,对水平方向的影响较小。灌水前期,土壤基质吸力的影响远大于重力,水分在垂直方向上的运移距离与水平方向相近;灌水中期,垂直向上与水平方向的渗透速率随坡度增大而变缓;灌水后期,垂直向下的渗透速率逐渐趋于由重力为主要诱使因素的稳定速率;相同灌水量下,流量越小,湿润锋运移距离越远;水分再分布时段,受重力梯度和基质势的综合影响,垂直向下的运移距离最远,水平方向次之,垂直向上最近;含水率等值线呈椭圆形分布,且垂直向下的含水率均大于垂直向上和水平方向的含水率。采用幂函数与二次函数均可拟合植被混凝土湿润锋运移距离与入渗时间的关系,其中幂函数拟合程度更佳(R²>0.95),但R²略小于一般天然土壤,拟合结果扩大了土壤水动力学理论在复合土壤的适用范围。

Moisture Migration of Vegetation Concrete Under Buried Drip Irrigation in Soil

The purpose of this study was to explore the influence of dripper discharge and slope factors on vegetation-concrete moisture migration by using composite artificial soil. The dynamics of wetting front of vegetation concrete and spatial-temporal distribution of soil moisture under buried drip irrigation in soil were studied, and the similarities and differences of moisture transfer between vegetation concrete and natural soil were discussed as well, which could provide theoretical reference for irrigation scheduling of drip irrigation during ecological restoration of high-steep slope. The results showed that dripper discharge rate and slope had the greatest influence on vertically upward moisture migration, but had little impact in horizontal direction. At the earlier stage of irrigation, the influence of soil matrix suction was much greater than that of gravity, and the vertically upward distance of moisture migration was similar to the horizontal distance. During the middle period, the infiltration rate in vertically upward and horizontal directions decreased with the increases of slopes. At the later stage, the vertically downward migration rate gradually tended to be stable, which was mainly induced by gravity. At the same irrigation volume, the smaller the flow rate, the farther the wetting front would migrate. During the period of moisture redistribution, the distance of vertically downward migration was the farthest, followed by horizontal direction, and vertically upward distance was the nearest. The contours of moisture content were oval, and vertically downward moisture content were larger than those in vertically upward and horizontal direction. Both power and quadratic functions could fit the relationship between the distance of wetting front migration and infiltration time, of which power function was better(R²>0.95), but R² was slightly smaller than that of natural soil, which expanded the application scope of Soil Hydrodynamics in the composite soil.