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Spectral scaling of heat fluxes in streambed sediments
KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Hydraulic Engineering.
KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Hydraulic Engineering.ORCID iD: 0000-0003-2716-4446
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2012 (English)In: Geophysical Research Letters, ISSN 0094-8276, Vol. 39, no 23, L23402- p.Article in journal (Refereed) Published
Abstract [en]

Advancing our predictive capabilities of heat fluxes in streams and rivers is important because of the effects on ecology and the general use of heat fluxes as analogues for solute transport. Along these lines, we derived a closed-form solution that relates the in-stream temperature spectra to the responding temperature spectra at various depths in the sediment through a physical scaling factor including the effective thermal diffusivity and the Darcy flow velocity. This analysis considers the range of frequencies in temperature fluctuations that occur due to diurnal and meteorological variation both in the long and short term. This approach provides insight regarding the key frequencies for analysing temperature responses at different depths within the sediment and also provides a simple and accurate method that offers quantitative insight into heat transport and surface water interactions with groundwater. We demonstrate for Sava Brook, Sweden, how the values of effective thermal diffusivities can be estimated based on the observed in-stream and sediment temperature time series and explain the temporal scaling of the heat transport as a function of a dimensionless frequency number. We find that the lower limit of periods of significance for the analysis increases with depth, and we recommend further research regarding appropriate frequency windows.

Place, publisher, year, edition, pages
2012. Vol. 39, no 23, L23402- p.
Keyword [en]
Temperature Time-Series, Tracer, Discharge, Exchange, Solutes
National Category
URN: urn:nbn:se:kth:diva-109608DOI: 10.1029/2012GL053922ISI: 000312094200002ScopusID: 2-s2.0-84870899209OAI: diva2:583749

QC 20130108

Available from: 2013-01-08 Created: 2013-01-08 Last updated: 2014-08-26Bibliographically approved
In thesis
1. Solute Transport Across Scales: Time Series Analyses of Water Quality Responses to Quantify Retention and Attenuation Mechanisms in Watersheds
Open this publication in new window or tab >>Solute Transport Across Scales: Time Series Analyses of Water Quality Responses to Quantify Retention and Attenuation Mechanisms in Watersheds
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The intra-continental movement of waterborne contaminants is governed by the distribution of solute load in the landscape along with the characteristics and distribution of the hydrological pathways that transport the solutes. An understanding of the processes affecting the transport and fate of the contaminants is crucial for assessments of solute concentrations and their environmental effect on downstream recipients. Elevated concentration of nutrients and the presence of anthropogenic substances, such as pharmaceutical residues, are two examples of the current problems related to hydrological transport. The overall objective of this thesis is to increase the mechanistic understanding of the governing hydrological transport processes and their links to geomorphological and biogeochemical retention and attenuation processes. Specifically, this study aims to quantify the processes governing the transport and fate of waterborne contaminants on the point, stream reach, and watershed scales by evaluating time series obtained from stream tracer tests and water quality monitoring data. The process quantification was achieved by deriving formal expressions for the key transport characteristics, such as the central temporal moments of a unit solute response function and the spectral scaling function for time series of solute responses, which attributes the solute response in the Laplace and Fourier domains to the governing processes and spatial regions within the watershed. The results demonstrate that in addition to the hydrological and biogeochemical processes, the distribution of the load in the landscape and the geomorphological properties in terms of the distribution of transport pathway distances have defined effects on the solute response. Furthermore, the spatial variability between and along the transport pathways significantly affect the solute response. The results indicate that environments with high retention and attenuation intensity, such as stream-reaches with pronounced hyporheic zones, may often dominate the solute flux in the watershed effluent, especially for reactive solutes. The mechanistic-based framework along with the evaluation methodologies presented within this study describes how the results can be generalized in terms of model parameters that reflect the hydrology, geomorphology and biogeochemistry in the studied area. This procedure is demonstrated by the parameterization of a compartment-in-series model for phosphorous transport.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. x, 62 p.
TRITA-LWR. PHD, ISSN 1650-8602 ; 2014:05
Solute transport modeling; Transient storage; Tracer test; Central temporal moments; Spectral analysis; Parameterization
National Category
Oceanography, Hydrology, Water Resources
urn:nbn:se:kth:diva-149528 (URN)978-91-7595-232-1 (ISBN)
Public defence
2014-09-12, F3, Lindstedtvägen 26, KTH, Stockholm, 10:00 (English)

QC 20140826

Available from: 2014-08-26 Created: 2014-08-22 Last updated: 2015-06-15Bibliographically approved

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Wörman, AndersRiml, JoakimBottacin-Busolin, Andrea
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