土壤质地和供水水头对负压灌溉土壤水分运移的影响研究

Influence of Soil Texture and Water-supply Head on Soil Water Transportation under Negative Pressure Irrigation

负压灌溉是在水源高程低于灌水器高程时实现灌溉,供水水头为负值,无需提水加压设备,自动补给灌溉。试验研究了不同土壤质地(黏壤土和沙土)和供水水头(h=0.5、0-、0.5-、1-、2 m)对负压灌溉湿润峰动态变化和累积入渗量的影响。试验结果表明:各处理的湿润锋开始时运移较快,等时间线较稀疏,随着灌溉时间增加,运移变慢,等时间线变密。湿润体都近似为椭球体。累计入渗量,最大水平和垂直湿润距离都随时间的增加而增大,入渗率都随时间的增加而减小,在正压和无压的条件下,沙土在相同时间段的累计入渗量、最大水平和垂直距离均比壤土大,而在负压的情况下,则反之。

This paper advances a system of negative pressure irrigation.By using this technology,the irrigation water can be automatically supplied from the irrigation water lower than the emitter without pumping system and greatly improve the utilization of water resources.The experiments study the influence of elevation difference between water source and emitter on the movement of water in two kinds of soil texture.The results show that in all cases,the wetting front advances quickly at first,but will be slowing down as time going on.The shape of wetting front are all nearly ellipsoid.The cumulative infiltration,maximum horizontal and vertical wetted distance increases with the advance of time,while the infiltration rate decreases with the advance of time.The cumulative infiltration,maximum horizontal and vertical wetted distance of sandy soil is larger than those of loamy soil under the conditions of pressure and no pressure,while it is contrary under the negative pressure.