Seasonal soil moisture patterns: Controlling transit time distributions in a forested headwater catchment
Seasonal soil moisture patterns: Controlling transit time distributions in a forested headwater catchment
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DOI：
10.1002/2013wr014815
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发表时间：
2014-06
影响因子：
5.4
通讯作者：
M. Stockinger;H. Bogena;A. Lücke;B. Diekkrüger;M. Weiler;H. Vereecken
中科院分区：
文献类型：
--
作者：
M. Stockinger;H. Bogena;A. Lücke;B. Diekkrüger;M. Weiler;H. Vereecken
汇流的通过时间分布(TTD)通常用于了解水流路径、蓄水特性和径流来源。尽管已有研究，但流域特征和TTDS之间的联系仍不完全清楚。我们介绍了在森林覆盖的乌斯特巴赫源头流域(38.5公顷)进行了两年稳定同位素示踪调查的结果，包括降水、溪流和支流位置。我们使用测量出口来确定有效降水量(PEF)，将其细分为干湿集水状态，并假设它在空间上是均匀的。然后，我们计算了14个有稳定同位素示踪信息的未测量河流和支流的TTD，并将它们与各自的分流域区域和分流域内河岸带的比例进行了比较。我们的方法洞察了武斯特巴赫河沿岸TTD的空间异质性。我们发现，水文山坡-河岸带断开是一个重要因素，因为集水区在两个不同的、随时间变化的水文响应之间转移，这两个响应由总集水区湿度的季节变化控制。河岸带和山坡的水文行为的差异可以解释经常遇到的“老水现象”，即相当数量的旧水迅速出现为径流。TTD结果表明，河岸带比例与平均渡越时间(MTT值)呈负相关，土壤水分测量的密集网络证实了这一点。未发现亚集水区大小与MTT值之间的相关性。
The Transit Time Distribution (TTD) of a catchment is frequently used for understanding flow paths, storage characteristics, and runoff sources. Despite previous studies, the connections between catchment characteristics and TTDs are still not fully understood. We present results from a 2 year stable isotope tracer investigation in the forested Wüstebach headwater catchment (38.5 ha), including precipitation, stream, and tributary locations. We used the gauged outlet to determine effective precipitation (peff), subdivided for wet and dry catchment state, and assumed it to be spatially uniform. We then calculated TTDs of 14 ungauged stream and tributary locations where stable isotope tracer information was available and compared them to respective subcatchment areas and the proportion of riparian zone within the subcatchments. Our approach gave insight into the spatial heterogeneity of TTDs along the Wüstebach River. We found that hydrological hillslope‐riparian zone disconnection was an important factor, as the catchment shifted between two distinct, time‐variant hydrological responses that were governed by seasonal changes of overall catchment wetness. The difference in hydrological behavior of the riparian zone and hillslopes could explain the often encountered “old water phenomenon,” where considerable amounts of old water quickly appear as runoff. TTD results showed a negative correlation between riparian zone proportion and Mean Transit Time (MTT), corroborated by the dense network of soil water content measurements. No correlation between subcatchment size and MTT was found.