间歇组合灌溉下中度盐碱土壤入渗规律

为了进一步揭示咸淡水间歇组合灌溉入渗的影响机制与规律,在室内采用垂直一维积水入渗试验,研究了不同间歇时间、组合次序下的土壤入渗特征;基于实测资料探讨3种常规的入渗模型对间歇组合灌溉在中度盐碱土壤入渗规律的适用性.结果显示:在同一入渗时间下,累积入渗量从大到小依次为间歇组合灌溉(0 min),间歇组合灌溉(30 min), 间歇组合灌溉(60 min), 间歇组合灌溉(120 min),且它们之间的差异随时间的延长越来越具有统计学意义;在整个入渗过程,入渗速率分为初渗阶段和稳渗阶段,且与先咸后淡相比,先淡后咸先到达稳定入渗率;与Green-Ampt模型、Philip模型相比,Kostiakov模型能更加准确地描述间歇组合灌溉的入渗率变化特征,但在Kostiakov模型中,先淡后咸拟合精度低于先咸后淡,说明咸淡水组合次序对模型拟合精度影响较大.

Infiltration characteristics under intermittent combined irrigation in moderately saline-alkali soil

In order to reveal the infiltration mechanism of intermittent combined irrigation,one-dimension vertical water infiltration experiments were conducted using a vertical soil column. The laboratory experiment comprised four intermittent times: 0 min,30 min,60 min and 120 min,with two combination sequences of F-B and B-F. Based on the measured data,the applicability of three infiltration mo-dels to predict and evaluate infiltration characteristics under intermittent combined irrigation in mode-rately saline-alkali soil was explored. The results show that the sequence of cumulative infiltration is intermittent combined irrigation( 0 min) > intermittent combined irrigation( 30 min) > intermittent combined irrigation( 60 min) > intermittent combined irrigation( 120 min) at the same infiltration time. Besides,significant difference exists in the cumulative infiltration with time. For the laboratory conditions used,the uniform and efficient intermittent combined irrigation could be achieved by considering the irrigation in two stages,the initial and steady infiltration stages. The results of simulation model indicate that the Kostiakov model can more acclrately describe the soil infiltration characteristics,compared with the Green-Ampt model and the Philip model. However,the Kostiakov model shows lower predictive power in F-B,which indicates that the combination sequences between fresh water and brackish water has a great influence on fitting precision.