水质及流量对盐碱土滴灌湿润锋运移影响的室内试验研究

Laboratory experiment study on the effects of water quality and emitter discharge on wetted soil geometry and volume

采用15°扇柱体有机玻璃土槽,研究了不同水质和滴头流量对盐碱土湿润锋运动的影响。试验所采用水的钠吸附比(SAR)分别为2和20,水的含盐浓度(C)分别为80、20mmol/L和蒸馏水,滴头流量分别为2、3.4和8L/h。试验结果表明:不同时间的二维湿润锋边界形状近似半椭圆形;在相同水质情况下,水平湿润距离和垂直湿润距离均随滴头流量的增加而增加;相同灌水量的情况下,滴头流量的增加有利于水分水平方向的发展,不利于垂直方向的发展;用蒸馏水灌溉时,水平湿润距离明显高于其他含盐水灌溉的情况,垂直湿润距离明显小于其他含盐水灌溉的情况;不同浓度含盐水滴灌时对湿润锋的影响不明显;湿润锋的宽深比随着灌溉时间的持续而减小。

A series of laboratory experiments were conducted to quantify the influences of rate on the patterns of the wetted soil column and the wetting front dynamics. An alkaline （2, 3.4, 8 L/h）, five saline levels of irrigating water （four different combinations of SAR irrigating water salinity, emitter discharge silt clayey loamy soil, three discharge rates 20and 2 andC =80, 20 mmol/L, as well as distilled water, DW）, were used in the experiments. A 15° wedge-shaped plexiglass container was used to represent one twentyfourth of the complete cylinder. The results indicated that drip irrigation of different discharge rates with different quality of irrigating water had its significant influences on the wetted patterns. Higher discharge rate produced higher lateral or horizontal movement of soil water under the same water quality. The increase of emitter discharge is the advantage of horizontal movement of soil water, while disadvantage of lateral movement of soil water under the same water application; Irrigation with DW yielded very lower vertical infiltration and the horizontal water advance was much faster, which is not good for salt leaching and may cause surface runoff. Irrigation with saline water produced faster horizontal water movement initially and with irrigation going on, vertical infiltration tended to increase as compared with the lateral movement.