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DOI	10.5194/hess-22-3841-2018
	Sensitivity of young water fractions to hydro-climatic forcing and landscape properties across 22 Swiss catchments
	Von Freyberg J.; Allen S.T.; Seeger S.; Weiler M.; Kirchner J.W.
发表日期	2018
ISSN	1027-5606
起始页码	3841
结束页码	3861
卷号	22 期号:7
英文摘要	The young water fraction Fyw, defined as the proportion of catchment outflow younger than approximately 2-3 months, can be estimated directly from the amplitudes of seasonal cycles of stable water isotopes in precipitation and streamflow. Thus, Fyw may be a useful metric in catchment inter-comparison studies that investigate landscape and hydro-climatic controls on streamflow generation. Here, we explore how Fyw varies with catchment characteristics and climatic forcing, using an extensive isotope data set from 22 small-to medium-sized (0.7-351 km2) Swiss catchments. We find that flow-weighting the tracer concentrations in streamwater resulted in roughly 26% larger young water fractions compared to the corresponding unweighted values, reflecting the fact that young water fractions tend to be larger when catchments are wet and discharge is correspondingly higher. However, flow-weighted and unweighted young water fractions are strongly correlated with each other among the catchments. They also correlate with terrain, soil, and land-use indices, as well as with mean precipitation and measures of hydrologic response. Within individual catchments, young water fractions increase with discharge, indicating an increase in the proportional contribution of faster flow paths at higher flows. We present a new method to quantify the discharge sensitivity of Fyw, which we estimate as the linear slope of the relationship between the young water fraction and flow. Among the 22 catchments, discharge sensitivities of Fyw are highly variable and only weakly correlated with Fyw itself, implying that these two measures reflect catchment behaviour differently. Based on strong correlations between the discharge sensitivity of Fyw and several catchment characteristics, we suggest that low discharge sensitivities imply greater persistence in the proportions of fast and slow runoff flow paths as catchment wetness changes. In contrast, high discharge sensitivities imply the activation of different dominant flow paths during precipitation events, such as when subsurface water tables rise into more permeable layers and/or the river network expands further into the landscape. © Author(s) 2018.
语种	英语
scopus关键词	Groundwater; Isotopes; Land use; Runoff; Stream flow; Catchment characteristics; Hydrologic response; Landscape properties; Precipitation events; Stable water isotopes; Streamflow generations; Strong correlation; Tracer concentration; Catchments; catchment; climate forcing; concentration (composition); discharge; landscape; outflow; precipitation (climatology); runoff; seasonal variation; sensitivity analysis; streamflow; streamwater
来源期刊	Hydrology and Earth System Sciences
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/159969
作者单位	Von Freyberg, J., Department of Environmental Systems Science, ETH Zurich, Zurich, Switzerland, Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf, Switzerland; Allen, S.T., Department of Environmental Systems Science, ETH Zurich, Zurich, Switzerland; Seeger, S., Faculty of Environment and Natural Resources, University of Freiburg, Freiburg im Breisgau, Germany; Weiler, M., Faculty of Environment and Natural Resources, University of Freiburg, Freiburg im Breisgau, Germany; Kirchner, J.W., Department of Environmental Systems Science, ETH Zurich, Zurich, Switzerland, Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf, Switzerland
推荐引用方式 GB/T 7714	Von Freyberg J.,Allen S.T.,Seeger S.,et al. Sensitivity of young water fractions to hydro-climatic forcing and landscape properties across 22 Swiss catchments[J],2018,22(7).
APA	Von Freyberg J.,Allen S.T.,Seeger S.,Weiler M.,&Kirchner J.W..(2018).Sensitivity of young water fractions to hydro-climatic forcing and landscape properties across 22 Swiss catchments.Hydrology and Earth System Sciences,22(7).
MLA	Von Freyberg J.,et al."Sensitivity of young water fractions to hydro-climatic forcing and landscape properties across 22 Swiss catchments".Hydrology and Earth System Sciences 22.7(2018).