地表滴灌条件下滴头流量对土壤水分入渗—再分布过程的影响

在新疆林业科学院枣树示范基地进行了原状土的树下单点源滴灌试验,研究砂壤土在不同滴头流量条件下(滴头流量分别为8、12、16 L·h~(-1))地表滴灌湿润体特征值的变化规律。结果表明:1停止灌溉时湿润锋呈平卧半椭球体分布,随着滴头流量的增加湿润锋的分布范围逐渐增大,停止灌溉后12 h内各滴头流量下土壤中的水分运移均存在再分布过程,水分再分布后湿润锋呈直立半椭球体分布,湿润体的形状大小受到滴头流量及灌溉总量的影响,湿润锋水平、垂直运移距离与入渗时间存在显著的幂函数关系,决定系数(R~2)均大于0.95;2滴灌初期湿润锋在水平、垂直方向上的运移速率随着滴头流量的增加而增大,随着灌水历时的延长逐渐降低,滴头流量越大入渗距离比也就越大,并且随着灌溉时间的推移入渗距离比值逐渐减小,三种滴头流量下入渗距离比由最初的2~2.27逐渐减小到0.8~0.97;3随着滴头流量的增大湿润体的体积不断增大,湿润体含水量也随之增大,距离滴头越近含水量等值线越密,外围含水量等值线较稀疏,滴头正下方约40 cm处土壤含水量增加值达到最大,再分布后含水量等值线变为稀疏,水平扩散半径增加值较小,垂直方向再分布距离较大。

Effects of different dripper discharges on soil water infiltration/redistribution under drip irrigation

The objective of the study was conducted to investigate the variations of different dripper discharges on the characteristic values of the wetted body under sand soil in the Jujube demonstration base of Xinjiang Academy of Forestry Sciences .The result showed that when irrigation was stopped ,the wetting front performed like a lying semi-ellip-soid .With the increase of the dripper discharge ,the distribution range of the wetting front was also increased .12 hours after irrigation was stopped ,soil moisture transport under each dripper discharge was redistributed .The wetting front re-sembled an upright semi-ellipsoid after redistribution .The moist body size and shape were affected by the dripper dis-charge and irrigation amount .There was a significant power function between the horizontal and vertical transport distance and infiltration time with an R2≥0 .95 .In addition ,at early irrigation stage ,the migration rate of wetting front in the horizontal and vertical became increased with amount of dripper discharge ,and went decreased with irrigation time .The larger the dripper discharge ,the greater the infiltration distance ratio .Infiltration distance ratio was decreased with irriga-tion time .The infiltration distance ratio from an initial value 2-2 .27 was gradually reduced to 0 .8~0 .97 under three dripper flows .Furthermore ,with the increase in dripper discharge volume ,the volume of moist body and water content of soil became increased as well .Drip distance influenced moisture contour .Soil moisture content reached maximal 40cm below the dripper .After redistribution ,the moisture contour became sparse ,the horizontal diffusion radius was small , and the vertical redistribution distance was large .