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From precipitation to stream

isotopic insights into hydrological flow paths and transit times in boreal catchments

Peralta-Tapia, Andres (2015). From precipitation to stream. Diss. (sammanfattning/summary) Umeå : Sveriges lantbruksuniv., Acta Universitatis agriculturae Sueciae, 1652-6880 ; 2015:64
ISBN 978-91-576-8326-7
eISBN 978-91-576-8327-7
[Doctoral thesis]

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Abstract

Understanding the journey water makes from precipitation entering a catchment, traveling through soils, and the time it takes before it exits as stream water are questions of great relevance for both scientists and environmental managers. Natural stable isotopes such as δ¹⁸O and δ²H have been extensively used over the last decades to trace water through diverse catchments across the world. In this thesis I analyzed over 2500 isotope samples to create long-term time series of precipitation and stream water data, as well as studying spatial and temporal variability of flow pathways in the Krycklan catchment in Northern Sweden. Based on these isotope samples, I observed that streams draining forested catchments were fed by soil water from different horizons throughout the year. In contrast, stream water from mire dominated catchments was linked primarily to one hydrological active layer with the exception of the winter season when both catchment types showed influence of old/deep groundwater. ²³⁴U/²³⁸U isotope ratios further enhanced the mechanistic understanding of old groundwater where δ¹⁸O signature could not be used to disentangle sources. During a winter baseflow survey I found a the contribution of old groundwater to stream water among 78 sub-catchments, which increased with area ranging from ~20 % contribution in the smaller headwater sub-catchments up to 70-80 % for catchments with areas 10.6 km² or larger. Additionally, I found that the spatial variability of old groundwater contribution to catchments below ~10.6 km² was influenced by differences in structural properties across sub-catchments. Furthermore, dissolved organic carbon (DOC) was negatively correlated with old groundwater contribution, while base cations and pH were positively correlated. Finally, annual water transit time in the snow-dominated boreal catchment with the most complete isotopic record ranged between 300 and 1400 days and was negatively related to annual rain input. This relationship may have implications for our understanding of future hydrological and biogeochemical processes in boreal regions, given that warmer winters are forecasted, which would translate to larger proportions of precipitation falling as rain. Overall, this thesis has taken us one step further in the search for mechanistic understanding of hydrological flow paths and transit times in small to meso-scale boreal catchments.

Authors/Creators:Peralta-Tapia, Andres
Title:From precipitation to stream
Subtitle:isotopic insights into hydrological flow paths and transit times in boreal catchments
Series/Journal:Acta Universitatis agriculturae Sueciae (1652-6880)
Year of publishing :2015
Depositing date:8 March 2015
Volume:2015:64
Number of Pages:36
Papers/manuscripts:
NumberReferences
IA. Peralta-Tapia, R. Sponseller, D. Tetzlaff, C. Soulsby and H. Laudon (2014). Connecting precipitation inputs and soil flow pathways to stream water in contrasting boreal catchments. Hydrological Processes. Accepted online.
IIF. Lidman, A. Peralta Tapia, A. Vesterlund and H. Laudon. 234U/238U in a boreal stream network – relationship to hydrological events, groundwater and scale. Submitted manuscript.
IIIA. Peralta-Tapia, R. Sponseller, A. Ågren, D. Tetzlaff, C. Soulsby and H. Laudon (2015). Scale-dependent groundwater contributions influence patterns of winter baseflow stream chemistry in boreal catchments. Journal of Geophysical Research – Biogeosciences. Accepted online.
IVA. Peralta-Tapia, D. Tetzlaff, C. Soulsby, R. Sponseller, K. Bishop and H. Laudon. Hydroclimatic Controls on Non-Stationary Transit Time Distributions in a Boreal Headwater Catchment Over a 10 Year Period. (manuscript).
Place of Publication:Umeå
Publisher:Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
ISBN for printed version:978-91-576-8326-7
ISBN for electronic version:978-91-576-8327-7
ISSN:1652-6880
Language:English
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:P Natural resources > P10 Water resources and management
P Natural resources > P33 Soil chemistry and physics
Subjects:(A) Swedish standard research categories 2011 > 1 Natural sciences > 105 Earth and Related Environmental Sciences > Geochemistry
(A) Swedish standard research categories 2011 > 1 Natural sciences > 105 Earth and Related Environmental Sciences > Oceanography, Hydrology, Water Resources
Agrovoc terms:rivers, boreal forests, runoff, precipitation, isotopes, isotope analysis, groundwater
Keywords:Isotopes, path ways, natural tracers, transit time, spatial avriability, baseflow, time series, gamma distribution
URN:NBN:urn:nbn:se:slu:epsilon-e-2636
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-e-2636
ID Code:12193
Faculty:S - Faculty of Forest Sciences
Department:(S) > Dept. of Forest Ecology and Management
External funders:Swedish Research Council
Deposited By: Andres Peralta-Tapia
Deposited On:08 May 2015 14:07
Metadata Last Modified:04 Aug 2015 20:05

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