[目的] 对黄土沟壑区典型人工林刺槐、侧柏、油松的绿水流变化规律进行研究，为该区植树造林，促进水资源高效利用等工作提供科学指导。[方法] 首先对Granger模型在南小河沟流域典型人工林内的适用性进行评价，然后结合实测的低效绿水，对各林地内高、低效绿水进行了分离，并基于分离结果，分析总结无雨期各林地高、低效绿水变化特征及其与太阳辐射、叶面积指数、土壤含水率的关系。[结果] ①Granger模型在各林地内的适用性良好，其纳什效率系数在率定期以及验证期分别在0.67以及0.52以上。②各林地中，高效绿水在不同水文年的变化程度表现为：侧柏（45.93%） > 油松（28.81%） > 刺槐（6.11%）；低效绿水变化则表现为：油松（52.73%） > 侧柏（34.97%） > 刺槐（21.16%）；绿水流变化表现为侧柏（21.13%） > 刺槐（12.37%） > 油松（0.50%）。偏枯和特枯年份无雨期刺槐、侧柏、油松林地10 cm土层相对含水量低于50%的比例占90.1%，56.8%，64.0%和68.4%，70.1%，71.2%；20 cm土层相对含水量低于50%的占90.1%，61.0%，60.1%和80.0%，66.7%，50.5%。[结论] ①侧柏是对水分最敏感的树种。②不同水文年对侧柏高效绿水（45.93%）的影响大于低效绿水（34.97%），对刺槐和油松的影响则正好相反。③太阳辐射对侧柏低效绿水的影响最大，对刺槐高效绿水影响最大。刺槐和油松的低效绿水都随叶面积指数的增加而减少，高效绿水则随之增加。侧柏的高效绿水受叶面积指数影响较小。3种林地在试验期大部分时段内都处于中度缺水状态。
[Objective] In order to guide local afforestation and promote efficient use of water resources, the green water flow of the typical artificial forest of Robinia pseudoacacia, Platycladus orientalis and Pinus tabulaeformis was studied in the loess gully region.[Methods] The applicability of Granger model in typical artificial forest land in Nanxiaohegou sub-basin was evaluated. Then combined with the measured green water of low efficiency, the high and low efficiency green water in each forest was separated. And based on the separation results, we analyzed and summarized the characteristics of high and low efficiency green water changes in various forest land during the rain free period and their relationships with solar radiation, leaf area index, and soil moisture content.[Results] ① The Granger model has good applicability in various forest lands, and its Nash efficiency coefficient was above 0.67 and 0.52 in the regular period and verification period. ② In each forest land, the change of high efficiency green water in different hydrological years was Platycladus orientalis (45.93%) > Pinus tabulaeformis(28.81%) > Robinia pseudoacacia (6.11%). The change of low efficiency green water is Pinus tabulaeformis (52.73%) > Platycladus orientalis (34.97%) > Robinia pseudoacacia (21.16%). And the change of green water flow was Platycladus orientalis (21.13%) > Robinia pseudoacacia (12.37%) > Chinese pine (0.50%). Robinia pseudoacacia, Platycladus orientalis and Pinus tabulaeformis forest land with 10 cm relative water content less than 50% were 90.1%, 56.8%, 64.0% during dry year, and 68.4%, 70.1%, 71.2% during extremely dry year; 20 cm relative water content less than 50% are 90.1%, 61.0%, 60.1%, and 80.0%, 66.7%, 50.5%.[Conclusion] ① Platycladus orientalis was the most sensitive tree species for water. ② Different hydrological years have a greater impact on the high efficiency green water (45.93%) of Platycladus orientalis than the low-efficiency green water (34.97%), and the opposite was true for Robinia pseudoacacia and Pinus tabulaeformis. ③ Solar radiation had the greatest impact on the low efficiency green water in Platycladus orientalis, and the greatest impact on the high efficiency green water in the Robinia pseudoacacia forest. The low efficiency green water of Robinia pseudoacacia and Pinus tabulaeformis decreased with the increase of leaf area index while the high efficiency green water increased. The high-efficiency green water of Platycladus orientalis was less affected by the leaf area index. The three forest land was in a state of moderate water shortage during most of the experiment period.