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dc.contributor.author
Kirchner, James W.
dc.date.accessioned
2019-02-06T11:02:05Z
dc.date.available
2019-02-01T04:44:01Z
dc.date.available
2019-02-06T11:02:05Z
dc.date.issued
2019
dc.identifier.issn
1027-5606
dc.identifier.issn
1607-7938
dc.identifier.other
10.5194/hess-23-303-2019
en_US
dc.identifier.uri
http://hdl.handle.net/20.500.11850/322303
dc.identifier.doi
10.3929/ethz-b-000322303
dc.description.abstract
Decades of hydrograph separation studies have estimated the proportions of recent precipitation in streamflow using end-member mixing of chemical or isotopic tracers. Here I propose an ensemble approach to hydrograph separation that uses regressions between tracer fluctuations in precipitation and discharge to estimate the average fraction of new water (e.g., same-day or same-week precipitation) in streamflow across an ensemble of time steps. The points comprising this ensemble can be selected to isolate conditions of particular interest, making it possible to study how the new water fraction varies as a function of catchment and storm characteristics. Even when new water fractions are highly variable over time, one can show mathematically (and confirm with benchmark tests) that ensemble hydrograph separation will accurately estimate their average. Because ensemble hydrograph separation is based on correlations between tracer fluctuations rather than on tracer mass balances, it does not require that the end-member signatures are constant over time, or that all the end-members are sampled or even known, and it is relatively unaffected by evaporative isotopic fractionation. Ensemble hydrograph separation can also be extended to a multiple regression that estimates the average (or “marginal”) transit time distribution (TTD) directly from observational data. This approach can estimate both “backward” transit time distributions (the fraction of streamflow that originated as rainfall at different lag times) and “forward” transit time distributions (the fraction of rainfall that will become future streamflow at different lag times), with and without volume-weighting, up to a user-determined maximum time lag. The approach makes no assumption about the shapes of the transit time distributions, nor does it assume that they are time-invariant, and it does not require continuous time series of tracer measurements. Benchmark tests with a nonlinear, nonstationary catchment model confirm that ensemble hydrograph separation reliably quantifies both new water fractions and transit time distributions across widely varying catchment behaviors, using either daily or weekly tracer concentrations as input. Numerical experiments with the benchmark model also illustrate how ensemble hydrograph separation can be used to quantify the effects of rainfall intensity, flow regime, and antecedent wetness on new water fractions and transit time distributions.
en_US
dc.format
application/pdf
en_US
dc.language.iso
en
en_US
dc.publisher
Copernicus Publications
en_US
dc.rights.uri
http://creativecommons.org/licenses/by/4.0/
dc.title
Quantifying new water fractions and transit time distributions using ensemble hydrograph separation: Theory and benchmark tests
en_US
dc.type
Journal Article
dc.rights.license
Creative Commons Attribution 4.0 International
dc.date.published
2019-01-18
ethz.journal.title
Hydrology and Earth System Sciences
ethz.journal.volume
23
en_US
ethz.journal.issue
1
en_US
ethz.journal.abbreviated
Hydrol. Earth Syst. Sci.
ethz.pages.start
303
en_US
ethz.pages.end
349
en_US
ethz.version.deposit
publishedVersion
en_US
ethz.identifier.wos
ethz.identifier.scopus
ethz.publication.place
Göttingen
en_US
ethz.publication.status
published
en_US
ethz.leitzahl
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02350 - Dep. Umweltsystemwissenschaften / Dep. of Environmental Systems Science::02722 - Institut für Terrestrische Oekosysteme / Institute of Terrestrial Ecosystems::03798 - Kirchner, James W. / Kirchner, James W.
ethz.leitzahl.certified
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02350 - Dep. Umweltsystemwissenschaften / Dep. of Environmental Systems Science::02722 - Institut für Terrestrische Oekosysteme / Institute of Terrestrial Ecosystems::03798 - Kirchner, James W. / Kirchner, James W.
ethz.date.deposited
2019-02-01T04:44:06Z
ethz.source
SCOPUS
ethz.eth
yes
en_US
ethz.availability
Open access
en_US
ethz.rosetta.installDate
2019-02-06T11:02:26Z
ethz.rosetta.lastUpdated
2020-02-15T16:56:59Z
ethz.rosetta.exportRequired
true
ethz.rosetta.versionExported
true
ethz.COinS
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