滴灌条件下暗管滤层结构对排水、排盐效果的影响

为解决滴灌农田非饱和条件下暗管排水困难的问题,设置2种暗管滤层铺设方式,以常规暗管滤层进行排水为对照,基于室内土槽试验,分析了滤层铺设方式对暗管排水排盐效果的影响及其机理。T1处理为常规暗管滤层铺设方式,暗管四周铺设细砂滤层,T2处理为暗管上部铺设细砂,T3处理为细砂斜垫层斜铺连接体积质量分界层与暗管。结果表明,T1处理受土壤水滞后效应影响显著,暗管不排水,土壤水、盐积聚于暗管底部;T2、T3处理可在暗管上部产生局部饱和区,促使暗管排水。T2处理排水时所需历时较长,排出的水盐总量较少;T3处理可使暗管最早排水,排水时暗管下部土壤积盐最少,排水流量和排水盐总量最大。

Proposed Gravel Filters for Pipe-drain to Improve the Efficacy of the Drainage System under Drip Irrigation

We developed two gravel filters to resolve the difficulties associated with pipe-drain used to drain farm-land under drip irrigation when soil is under unsaturated condition. Soil tank experiment was conducted to test their efficacy in comparison with conventional filter in which fine sands were laid around the drain pipe. In the proposed filters, fine sands were either laid on the top of the drain pipe (T2), or obliquely connected tothe pipe. The results showed that in contrast to the control in which there was a significant delay or failure in drainage and-water and salt accumulated on the bottom of the pipe, the proposed two filters produced a local saturated zone above the pipe, facilitating water movement and drainage. The T3 filter took less time to drain the water than T2 and was hence more efficient to drain water and salt out of the soil.