Macropore flow of old water revisited: experimental insights from a tile-drained hillslope
Macropore flow of old water revisited: experimental insights from a tile-drained hillslope
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DOI：
10.5194/hess-17-103-2013
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发表时间：
2013-01-01
影响因子：
6.3
通讯作者：
McDonnell, J. J.
中科院分区：
文献类型：
--
作者：
Klaus, J.;Zehe, E.;McDonnell, J. J.
人们对将储存的水迅速释放到溪流中的机制知之甚少。在这里，我们使用一个瓷砖排水现场结合联合收割机大孔土壤在山坡规模的优势，至少部分控制较低的边界条件。我们进行了一系列的三个灌溉实验相结合的水文测量与稳定同位素和溴化物示踪剂，以更好地了解大孔基质的相互作用和存储的水释放过程在山坡尺度。在试验前后对灌溉水、瓦沟排水和土壤水的稳定同位素浓度进行了监测。在瓷砖排水过程线中，每5-15分钟测量一次溴化物。每个实验的不同初始条件被用来研究这些如何影响流动和运输。不同数量的灌溉水是必要的，以增加瓷砖排水高于基流水平。基于溴化物数据的过程线分离显示，灌溉水的贡献峰值瓦排水量的顺序为20%。氧-18和氘的数据与溴化物的数据是一致的，并表明，事件前的土壤水的瓷砖排水事件流量的贡献显着。然而，在整个实验过程中，土壤水的同位素组成向灌溉水的同位素组成收敛。混合计算表明，到灌溉实验结束时，整个剖面中20%的土壤水是灌溉水。同位素数据显示，瓷砖排水沟中的事件前水在20-40厘米土壤深度中被动员，其中大孔隙与基质的相互作用导致超过水分阈值后大孔隙流动的启动。
The mechanisms allowing the rapid release of stored water to streams are poorly understood. Here we use a tile-drained field site to combine macroporous soils at the hillslope scale with the advantage of at least partly controlled lower boundary conditions. We performed a series of three irrigation experiments combining hydrometric measurements with stable isotope and bromide tracers to better understand macropore-matrix interactions and stored water release processes at the hillslope scale. Stable isotope concentrations were monitored in the irrigation water, the tile-drain discharge and the soil water before and after the experiment. Bromide was measured every 5-15 min in the tile-drain hydrograph. Different initial conditions for each experiment were used to examine how these influenced flow and transport. Different amounts of irrigation water were necessary to increase tile-drain discharge above the baseflow level. Hydrograph separation based on bromide data revealed that irrigation water contributions to peak tile-drain discharge were on the order of 20%. Oxygen-18 and deuterium data were consistent with the bromide data and showed that pre-event soil water contributed significantly to the tile-drain event flow. However, the isotopic composition of soil water converged towards the isotopic composition of irrigation water through the course of the experiment. Mixing calculations revealed that by the end of the irrigation experiments 20% of the soil water in the entire profile was irrigation water. The isotopic data showed that the pre-event water in the tile drain was mobilized in 20-40 cm soil depth where the macropore-matrix interaction leads to an initiation of macropore flow after a moisture threshold is exceeded.