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Author Johnson, R.S.H.; Alila, Y.
Title Nonstationary stochastic paired watershed approach: Investigating forest harvesting effects on floods in two large, nested, and snow-dominated watersheds in British Columbia, Canada Type Journal Article
Year 2023 Publication Journal of Hydrology Abbreviated Journal
Volume 625 Issue Pages 129970
Keywords Probabilistic physics, Forest hydrology, Attribution science, Flood Frequency Analysis, Stochastic hydrology, Nonstationarity
Abstract Drawing on advances in nonstationary frequency analysis and the science of causation and attribution, this study employs a newly developed nonstationary stochastic paired watershed approach to determine the effect of forest harvesting on snowmelt-generated floods. Moreover, this study furthers the application of stochastic physics to evaluate the environmental controls and drivers of flood response. Physically-based climate and time-varying harvesting data are used as covariates to drive the nonstationary flood frequency distribution parameters to detect, attribute, and quantify the effect of harvesting on floods in the snow-dominated Deadman River (878 km2) and nested Joe Ross Creek (99 km2) watersheds. Harvesting only 21% of the watershed caused a 38% and 84% increase in the mean but no increase in variability around the mean of the frequency distribution in the Deadman River and Joe Ross Creek, respectively. Consequently, the 7-year, 20-year, 50-year, and 100-year flood events became approximately two, four, six, and ten times more frequent in both watersheds. An increase in the mean is posited to occur from an increase in moisture availability following harvest from suppressed snow interception and increased net radiation reaching the snowpack. Variability was not increased because snowmelt synchronization was inhibited by the buffering capacity of abundant lakes, evenly distributed aspects, and widespread spatial distribution of cutblocks in the watersheds, preventing any potential for harvesting to increase the efficiency of runoff delivery to the outlet. Consistent with similar recent studies, the effect of logging on floods is controlled not only by the harvest rate but most importantly the physiographic characteristics of the watershed and the spatial distribution of the cutblocks. Imposed by the probabilistic framework to understanding and predicting the relation between extremes and their environmental controls, commonly used in the general sciences but not forest hydrology, it is the inherent nature of snowmelt-driven flood regimes which cause even modest increases in magnitude, especially in the upper tail of the distribution, to translate into surprisingly large changes in frequency. Contrary to conventional wisdom, harvesting influenced small, medium, and very large flood events, and the sensitivity to harvest increased with increasing flood event size and watershed area.
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ISSN 0022-1694 ISBN Medium
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Notes Approved no
Call Number (up) THL @ christoph.kuells @ Johnson2023129970 Serial 245
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Author Klaus, J.; Külls, C.; Dahan, O.
Title Evaluating the recharge mechanism of the Lower Kuiseb Dune area using mixing cell modeling and residence time data Type Journal Article
Year 2008 Publication Journal of Hydrology Abbreviated Journal
Volume 358 Issue 3-4 Pages 304-316
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Publisher Elsevier Place of Publication Editor
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Notes Approved no
Call Number (up) THL @ christoph.kuells @ Klaus2008evaluating Serial 28
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Author Morin, E.; Grodek, T.; Dahan, O.; Benito, G.; Külls, C.; Jacoby, Y.; Van Langenhove, G.; Seely, M.; Enzel, Y.
Title Flood routing and alluvial aquifer recharge along the ephemeral arid Kuiseb River, Namibia Type Journal Article
Year 2009 Publication Journal of Hydrology Abbreviated Journal
Volume 368 Issue 1-4 Pages 262-275
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Publisher Elsevier Place of Publication Editor
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Notes Approved no
Call Number (up) THL @ christoph.kuells @ Morin2009flood Serial 26
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Author Müller, M.; Alaoui, A.; Külls, C.; Leistert, H.; Meusburger, K.; Stumpp, C.; Weiler, M.; Alewell, C.
Title Tracking water pathways in steep hillslopes by δ18O depth profiles of soil water Type Journal Article
Year 2014 Publication Journal of hydrology Abbreviated Journal
Volume 519 Issue Pages 340-352
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Publisher Elsevier Place of Publication Editor
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Notes Approved no
Call Number (up) THL @ christoph.kuells @ Mueller2014tracking Serial 20
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Author Musy, S.; Meyzonnat, G.; Barbecot, F.; Hunkeler, D.; Sültenfuss, J.; Solomon, D.K.; Purtschert, R.
Title In-situ sampling for krypton-85 groundwater dating Type Journal Article
Year 2021 Publication Journal of Hydrology X Abbreviated Journal
Volume 11 Issue Pages 100075
Keywords Noble gases, Tracers, Groundwater, Dating, Sampling Methodology
Abstract Krypton-85 and other radioactive noble gases are widely used for groundwater dating purposes. 85Kr analysis require large volumes of water to reach the analytical requirements. Conventionally, this water is pumped to the surface to be degassed with a gas extraction system. The large pumping rate may disturb the natural flow field and requires substantial field logistics. Hence, we propose a new in-situ degassing method, in which membrane contactors are used to degas the groundwater directly in the well and gas is collected at the surface. This way, field work is facilitated, groundwater system disturbance is minimized, and the gas sample is collected at a specific depth. We demonstrate the tightness of the system regarding atmospheric air contamination for a collection times of 24 h, which is sufficient for both low-level counting and laser-based counting methods for 85Kr. The minimal borehole diameter is 7.5 cm for the prototype presented in this research but can easily be reduced to smaller diameters. In a case study, we compare the results obtained with the new passive method with those from a conventional packer setup sampling. Additionally, 3H/3He samples were collected for both sampling regimes and the dating results were compared with those from 85Kr. A good agreement between tracer ages is demonstrated and the age stratigraphy is consistent with the expected age distribution for a porous unconfined aquifer. In addition, our study emphasizes the differences between the age information sampled with various methods. In conclusion, we demonstrate that the new in situ quasi-passive method provides a more representative age stratigraphy with depth in most cases.
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ISSN 2589-9155 ISBN Medium
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Notes Approved no
Call Number (up) THL @ christoph.kuells @ Musy2021100075 Serial 215
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