竖管地表滴灌与普通地表滴灌土壤水分运移特性对比试验研究

Comparative Experimental Study on Soil Water Transport Characteristics Between Vertiacl Pipe Surface Drip Irrigation and Common Surface Drip Irrigation

为探究竖管地表滴灌和普通地表滴灌土壤水分运动规律及区别,在室外同步进行2种滴灌模式下风沙土入渗和蒸发试验,对比分析了土壤水分分布、蒸发规律和土壤湿润锋运移特性。结果表明:(1)灌水量为2 L,2种滴灌模式下,随着滴头流量的增大,湿润体体积和灌水均匀度逐渐减小,湿润体含水率平均值逐渐增大,当滴头流量一定,竖管地表滴灌的湿润体体积大于普通地表滴灌,而灌水均匀系数小于普通地表滴灌;(2)不同滴头流量处理(0.3,0.4,0.6 L/h)蒸发7天结束后,普通地表滴灌土壤蒸发量分别占灌水量的32.5%,35.0%和40.0%,而竖管地表滴灌土壤蒸发量仅占灌水量的22.5%,说明竖管地表滴灌对土壤蒸发有明显的抑制作用;(3)相同灌水量(2 L)时,普通地表滴灌水平和垂直湿润锋运移距离均随滴头流量的增大而略有减小,竖管地表滴灌垂直向下湿润锋运移规律与普通地表滴灌相同,而水平和垂直向上方向运移规律相反;随着时间的延长,普通地表滴灌与竖管地表滴灌水平和垂直方向湿润锋比值均呈不断减小趋势,最后趋于稳定;(4)构建了包括滴头流量和灌水时间在内的普通地表滴灌湿润锋运移距离经验公式,验证所建经验公式的可靠性,均方根误差介于0.24~0.27 cm,纳什效率系数均大于0.985。研究结果可为竖管地表滴灌技术应用提供理论参考。

In order to explore the laws and differences of soil water movement between the vertical-pipe drip irrigation and the common surface drip irrigation,two types of sand infiltration and evaporation tests were carried out simultaneously outdoors.And the distribution of soil water,evaporation regularities and transport characteristics of soil wetting front were compared and analyzed.The results showed that:(1)When the irrigation volume was fixed 2 L,the volume and uniformity of irrigation water gradually decreased with the increasing drip emitter flow,while the average water content of the wetting pattern dimensions gradually increased.When the drip emitter flow was constant,the water content of the wetted body in the vertical-pipe drip irrigation was higher than that in the common surface drip irrigation,while the irrigation uniformity was lower.(2)After 7 days of evaporation,with different drip emitter flow treatments,the soil evaporation of the surface drip irrigation accounted for 32.5%,35.0%and 40.0%of irrigation amount respectively,while the vertical-pipe drip irrigation only accounted for 22.5%,indicating that the vertical pipe drip irrigation significantly inhibited the soil evaporation.(3)When the irrigation amount was 2 L,the migration distances of wetting fronts of the common surface drip irrigation in horizontal and vertical directions decreased slightly with the increase of drip emitter discharge.In the law of the vertical downward movement of vertical surface drip irrigation was similar to the common surface drip irrigation,while the movement in the horizontal and vertical upward directions were opposite.However,with the increase of infiltration time,the transport distance ratios of wetting front in horizontal and vertical direction between common surface drip irrigation and vertical surface drip irrigation showed a decreasing trend and finally tended to be stable.(4)The wetting front migration distance empirical formula,including drip emitter flow and irrigation time,was constructed.And the reliability was verified with the prediction error statistics.That is,the mean square root errors were between 0.24 and 0.27 cm and the Nash efficiency coefficients were greater than 0.985.The research results are expected to provide references for the further researches of vertical pipe drip irrigation.