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Andrew FramptonUniversitetslektor, Docent

Undervisning

Kurser på mastersnivå (ges på engelska)
GE8037 Advanced hydrogeology 7.5 ECTS
GE7051 Permafrost - interactions with ecosystems and hydrology 15 ECTS

Kurser på grundnivå
GE4029 Kvartärgeologi och hydrologi 10 hp
GE5029 Hydrologi och vattenresurser 7,5 hp

Forskning

Arctic and subarctic hydrology, hydrogeology and transport

Arctic and subarctic environments are particularly sensitive and susceptible to climate change effects, where changes in groundwater systems may strongly impact downstream recipients, affecting water resources and quality. Quantifying degrading permafrost and associated carbon releases also plays a major role in understanding key climate feedback mechanisms.

Understanding the links between permafrost change and its influence on water flow and waterborne carbon transport is important for addressing and quantifying arctic terrestrial feedbacks to climate change. This since many permafrost regions contain large quantities of stored carbon in soil, located near the ground surface most susceptible to effects of warming. As the active layer degrades and deepens, increased gaseous release of carbon-dioxide and methane to the atmosphere is expected, which may potentially be an important positive feedback to climatic warming. The release of stored carbon is however affected by transport of subsurface water to surface water and ecosystems prior to release as gaseous CO2.

This research theme involves investigating climate-driven changes and feedback mechanisms related to the interactions of subsurface hydrogeological flow and transport, permafrost change and carbon releases to the atmosphere and water systems in cold regions, with specific application to northern arctic and subarctic sites along a climate gradient.  The specific objectives include to investigate and quantify process and system links of changing permafrost – hydrology-hydrogeology – waterborne carbon transport – gaseous carbon releases, by developing methodologies for assembling such process and system modelling capabilities. Available observations on relevant change mechanisms are used for model testing and model interpretation of data from several arctic and subarctic sites of on-going field investigations, including, but not limited to, sites located in northern Sweden, Greenland, and Svalbard.

 

Flow and transport in fractured rock

Analysing flow and transport phenomena in sparsely fractured media is important for understanding how natural geological environments function as barriers against transport of contaminants and other substances stored in subsurface geological repositories. Sparsely fractured crystalline bedrock is a favourable environment due to weak advective flow and strong retention properties, where the interplay between advective and dispersive flow strongly impacts both inert and reactive transport. The natural bedrock can thereby delay transport of waterborne substances for considerable amounts of time, allowing sorption and decay processes to limit release to the biosphere.

There are however many challenges involved in characterising, quantifying and modelling subsurface flow and transport, mainly due to great geological complexity and variability of the subsurface. Also, there are limitations in availability of field data and uncertainties related to conditioning models against relevant field measurements, in particular related to flow information, and in being able to describe how meaningful uncertainties impact application-significant assessments.

This research theme involves developing and applying methods for numerical fracture network modelling combined with analytical, semi-analytical and algorithmic approaches to investigate flow, flow pathways, and transport processes in geological fractured media, based on application of relevant field data. In particular, applications towards storage of spent nuclear fuel related to the Swedish and Finnish site characterisation campaigns are considered. Here transport of radionuclide particles is of main interest. Also, applications involving carbon capture and storage (CCS) are considered, where caprocks can act as practically impermeable layers to gaseous carbon release from subsurface storage of supercritical carbon dioxide.

 

Multiphase flow in coupled fractured-porous media

A candidate environment for deep geological storage of spent nuclear fuel is sparsely fractured crystalline rock, since these typically offer low-permeable and long-term stable conditions. However, canister deposition holes and the repository tunnel system need to be back-filled with buffer material, typically containing bentonite clays. Thereby, upon closure, the repository will undergo a multiphase flow process as groundwater seepage re-saturates the subsurface tunnel system.

The prevalence of those transient unsaturated conditions in porous and fractured media generally has a considerable influence on the flow field and thereby also on transport. Specifically, the occurrence of mixed gas-water flows may influence the environment near the deposition holes as well as the physical and biogeochemical processes along potential transport pathways from repository depth. There are numerous scientific investigations of two-phase flow behaviour in soil systems, but much fewer observations for these types of engineered bentonite-clay buffer systems. In particular, effects of buoyancy and bubble trapping may differ in fractured bedrock from those in classical soil environments. A comprehensive understanding of multiphase flows in a coupled bedrock-bentonite system is therefore necessary.

 

Publications

Peer-reviewed articles, selected

Magnússon, R.Í., Hamm, A., Karsanaev, S.V., Limpens, J., Kleijn, D., Frampton, A., Maximov, T.C., Heijmans, M.M.P.D. (2022). Extremely wet summer events enhance permafrost thaw for multiple years in Siberian tundra. Nat Commun 13, 1556. https://doi.org/10.1038/s41467-022-29248-x

Hamm, A., Frampton, A. (2021). Impact of lateral groundwater flow on hydrothermal conditions of the active layer in a high-Arctic hillslope setting. The Cryosphere 15, 4853–4871. https://doi.org/10.5194/tc-15-4853-2021

Stock, B., Frampton, A. (2021). Flow Experiments Through 3D Printed Rough-Walled Single-Fracture Replicas. Presented at the 3rd International Discrete Fracture Network Engineering Conference, Houston, Texas, USA, p. DFNE 21-2340.

Åhlén, I., Hambäck, P., Thorslund, J., Frampton, A., Destouni, G., Jarsjö, J. (2020). Wetlandscape size thresholds for ecosystem service delivery: Evidence from the Norrström drainage basin, Sweden. Science of The Total Environment, 704, 135452. https://doi.org/10.1016/j.scitotenv.2019.135452

Frampton, A., Hyman, J. D., & Zou, L. (2019). Advective transport in discrete fracture networks with connected and disconnected textures representing internal aperture variability. Water Resources Research, 2018WR024322. https://doi.org/10.1029/2018WR024322

Grenier, C., Anbergen, H., Bense, V., Chanzy, Q., Coon, E., Collier, N., Costard, F., Ferry, M., Frampton, A., Frederick, J., Gonçalvès, J., Holmén, J., Jost, A., Kokh, S., Kurylyk, B., McKenzie, J., Molson, J., Mouche, E., Orgogozo, L., Pannetier, R., Rivière, A., Roux, N., Rühaak, W., Scheidegger, J., Selroos, J.-O., Therrien, R., Vidstrand, P., Voss, C., 2018. Groundwater flow and heat transport for systems undergoing freeze-thaw: Intercomparison of numerical simulators for 2D test cases. Advances in Water Resources 114, 196–218. https://doi.org/10.1016/j.advwatres.2018.02.001

Schuh, C., Frampton, A., Christiansen, H.H., 2017. Soil moisture redistribution and its effect on inter-annual active layer temperature and thickness variations in a dry loess terrace in Adventdalen, Svalbard. TC 11, 635–651. https://doi.org/10.5194/tc-11-635-2017

Ströberg, A., Ebert, K., Jarsjö, J., Frampton, A., 2017. Contaminated area instability along Ångermanälven River, northern Sweden. Environmental Monitoring and Assessment 189. https://doi.org/10.1007/s10661-017-5839-0

Dessirier, B., Åkesson, M., Lanyon, B., Frampton, A., Jarsjö, J., 2016. Reconstruction of the water content at an interface between compacted bentonite blocks and fractured crystalline bedrock. Applied Clay Science. doi:10.1016/j.clay.2016.10.002

Gisnås, K., Etzelmüller, B., Lussana, C., Hjort, J., Sannel, A.B.K., Isaksen, K., Westermann, S., Kuhry, P., Christiansen, H.H., Frampton, A., Åkerman, J., 2016. Permafrost Map for Norway, Sweden and Finland: Permafrost map for Norway, Sweden and Finland. Permafrost and Periglacial Processes. doi:10.1002/ppp.1922.

Dessirier, B., Frampton, A., Fransson, Å., Jarsjö, J., 2016. Modeling early in situ wetting of a compacted bentonite buffer installed in low permeable crystalline bedrock. Water Resources Research 52, 6207–6221. doi:10.1002/2016WR018678.

Pannetier, R., Frampton, A., 2016. Air warming trends linked to permafrost warming in the sub-Arctic catchment of Tarfala, Sweden. Polar Research 35. doi:10.3402/polar.v35.28978.

Sjöberg, Y., Coon, E., Sannel, A.B.K., Pannetier, R., Harp, D., Frampton, A., Painter, S.L., Lyon, S.W., 2016. Thermal effects of groundwater flow through subarctic fens-A case study based on field observations and numerical modeling. Water Resources Research. doi:10.1002/2015WR017571.

Frampton, A., Destouni, G., 2015. Impact of degrading permafrost on subsurface solute transport pathways and travel times. Water Resources Research 51, 7680–7701. doi:10.1002/2014WR016689.

Dessirier, B., Frampton, A., Jarsjö, J., 2015. A global sensitivity analysis of two-phase flow between fractured crystalline rock and bentonite with application to spent nuclear fuel disposal. Journal of Contaminant Hydrology 182, 25–35. doi:10.1016/j.jconhyd.2015.07.006.

Frampton, A., 2014, Fracture transmissivity estimation using natural gradient flow measurements in sparsely fractured rock. In Fractured Rock Hydrogeology, International Association of Hydrogeologists (Sharp, J.M., Jr., and Troeger, U., eds.). doi:10.1201/b17016-10.

Dessirier, B., Jarsjö, J., Frampton, A., 2014. Modeling Two-Phase-Flow Interactions Across a Bentonite Clay and Fractured Rock Interface. Nuclear Technology. doi:10.13182/NT13-77.

Frampton, A., Painter, S.L., Destouni, G. 2013. Permafrost degradation and subsurface-flow changes caused by surface warming trends. Hydrogeology J, 21:271–280, doi: 10.1007/s10040-012-0938-z.

Sjöberg, Y., Frampton, A., Lyon, S.W. 2013. Using streamflow characteristics to explore permafrost thawing in northern Swedish catchments. Hydrogeology J, 21:271-280, doi: 10.1007/s10040-012-0932-5.

Cvetkovic, V. and Frampton, A. 2012, Solute transport and retention in three-dimensional fracture networks, Water Resour. Res., 48, W02509, doi:10.1029/2011WR011086.

Frampton, A., Painter, S., Sjöberg, Y, and Destouni, G., 2011, Transient modelling of permafrost dynamics in changing climate scenarios, 7th IEEE proceedings, PID2087089, 113-118, Stockholm, doi:10.1109/eScience.2011.24

Frampton, A., Painter, S., Lyon, S.W., and Destouni, G., 2011, Non-isothermal, three-phase simulations of near-surface flows in a model permafrost system under seasonal variability and climate change, Journal of Hydrology, 403, 352-359, doi: 10.1016/j.jhydrol.2011.04.010.

Frampton, A. and Cvetkovic, V., 2011, Numerical and analytical modeling of advective travel times in realistic three-dimensional fracture networks, Water Resour. Res., 47, W02506, doi:10.1029/2010WR009290.

Frampton, A. and Cvetkovic, V., 2010. Inference of field scale fracture transmissivities in crystalline rock using flow log measurements, Water Resour. Res., 46, W05506, doi: 10.1029/2009WR008367.

Fiori, A., Boso, F., de Barros, F.P.J., de Bartolo, S., Frampton, A., Severino, G., Suweis, S., Dagan, G., 2010. An Indirect Assessment on the Impact of Connectivity of Conductivity Classes upon Longitudinal Asymptotic Macrodispersivity, Water Resour. Res., 46, W11502, doi:10.1029/2009WR008590.

Cvetkovic, V. and Frampton, A., 2010. Transport and retention from single to multiple fractures in crystalline rock at Äspö (Sweden): 2. Fracture flow simulations and global retention properties, Water Resour. Res., 46, W05506, doi:10.1029/2009WR008030.

Frampton, A. and Cvetkovic, V., 2009. Significance of injection modes and heterogeneity on spatial and temporal dispersion of advecting particles in two-dimensional discrete fracture networks, Advances in Water Resources, 32, ADWR1301, doi: 10.1016/j.advwatres.2008.07.010.

Frampton, A. and Cvetkovic, V., 2007. Upscaling particle transport in discrete fracture networks: 2. Reactive tracers, Water Resour. Res., 43, W10429, doi:10.1029/2006WR005336.

Frampton, A. and Cvetkovic, V., 2007. Upscaling particle transport in discrete fracture networks: 1. Nonreactive tracers, Water Resour. Res., 43, W10428, doi:10.1029/2006WR005334.

Landeryou, M., Eames, I., Frampton, A., Cottenden, A.M., 2004. Modelling strategies for liquid spreading in medical absorbents. International Journal of Clothing Science and Technology 16, 163–172, doi:10.1108/09556220410520441

Eames, I., Small, I., Frampton, A., Cottenden, A.M., 2003. Experimental and theoretical study of the spread of fluid from a point source on an inclined incontinence bed-pad. Journal of Engineering in Medicine 217, 263–271, doi:10.1243/095441103322060712

Landeryou, M., Cottenden, A., Eames, I., Frampton, A., 2003. Bulk Liquid-transport Properties of Multi-layered Fibrous Absorbents. Journal of the Textile Institute 94, 67–76, doi:10.1080/00405000308630629.

 

Monographs

Frampton, A., 2010. Stochastic analysis of fluid flow and tracer pathways in crystalline fracture networks. Doctoral Thesis, KTH. US AB, Stockholm, Sweden. ISBN 978-91-7415-560-0. ISSN 1650-8602. ISRN KTH/LWR/PHD 1056-SE. TRITA LWR PhD 1056. Link

 

Technical reports

Dessirier, B., Frampton, A., and Jarsjö, J., 2017. Two-phase flows during re-saturation of sparsely fractured bedrock and bentonite around canisters for deep storage of spent nuclear fuel – Modelling Task 8 of SKB Task Forces GWFTS and EBS (No. P-17-02) (p. 48). Swedish Nuclear Fuel and Waste Management Co (SKB), Stockholm, Sweden. URL: https://www.skb.com/publication/2489155/P-17-02.pdf

Frampton, A., Gotovac, H., Holton, D., Cvetkovic, V., 2015. Äspö Task Force on modelling of groundwater flow and transport of solutes. Task 7 – Subsurface flow and transport modelling of hydraulic tests and in situ borehole flow measurements conducted at Olkiluoto Island (No. P-13-42). Swedish Nuclear Fuel and Waste Management Co (SKB), Stockholm.

Frampton, A., Cvetkovic, V., and Holton, D., 2009. Äspö Task Force on modelling of groundwater flow and transport of solutes – Task 7A. Task 7A1 and 7A2: Reduction of performance assessment uncertainty through modelling of hydraulic tests at Olkiluoto, Finland. International Technical Document ITD-09-05. Svensk Kärnbränslehantering AB, Stockholm, Sweden.

 

Book review

Frampton, A., 2014. P. M. Adler, J.-F. Thovert, V. V. Mourzenko: Fractured Porous Media: Oxford University Press, 2013, pp. 175. Mathematical Geosciences 46, 771–773. doi:10.1007/s11004-014-9527-0

 

Open access computer programs

Frampton, A., Dessirier, B., Pannetier, R., 2014. Visual PyFlow – an open-source graphical solver of the groundwater flow equation. Available at https://bitbucket.org/Visual_PyFlow.

 

Selected contributions at scientific conferences and workshops

Åhlén, I., Hambäck, P., Thorslund, J., Frampton, A., Destouni, G., Jarsjö, J., 2020. Wetlandscape size thresholds for multiple ecosystem service delivery. Presented at the EGU2020, Copernicus Meetings, pp. EGU2020-1622. https://doi.org/10.5194/egusphere-egu2020-1622

Frampton, A., Zou, L., 2020. Dispersion in small-scale discrete fracture networks with internal fracture roughness: Challenges for site-scale modelling. Presented at the EGU2020, Copernicus Meetings, pp. EGU2020-21854. https://doi.org/10.5194/egusphere-egu2020-21854

Frampton, A., Zou, L., 2019. Analysis of flow and transport pathways in numerical models of fracture networks with small-scale heterogeneity. Presented at the EGU General Assembly, Copernicus Meetings, Vienna, p. 16657.

Ruvalcaba Baroni, I., Bayer, T., Gustafsson, E., Frampton, A., Beer, C., 2019. Methane and carbon dioxide evasion from Arctic lakes: A methodological review. Presented at the EGU General Assembly, Copernicus Meetings, p. 4935.

Frampton, A., Hyman, J. D., & Zou, L. (2018). Advective Transport in a Synthetic Discrete Fracture System With Internal Variability in Permeability. In ARMA-DFNE-18-0932 (p. 8). Seattle, Washington, USA: American Rock Mechanics Association.

Frampton, A. (2017). Subsurface flow pathway dynamics in the active layer of coupled permafrost-hydrogeological systems under seasonal and annual temperature variability. In EGU General Assembly Conference Abstracts (Vol. 19, p. 9289). Retrieved from http://meetingorganizer.copernicus.org/EGU2017/session/24601

Schuh, C., Frampton, A., & Christiansen, H. H. (2017). Effects of soil moisture retention on ice distribution and active layer thickness subject to seasonal ground temperature variations in a dry loess terrace in Adventdalen, Svalbard. In EGU General Assembly Conference Abstracts (Vol. 19, p. 9242). Retrieved from http://meetingorganizer.copernicus.org/EGU2017/EGU2017-9242.pdf

Zou, L., & Frampton, A. (2018). Impacts of Dead-ends on Flow and Transport in Fractured Rocks. In 52nd US Rock Mechanics / Geomechanics Symposium (Vol. 18–1141). Seattle, Washington, USA.

Frampton, A., & Hyman, J. D. (2017). Flow channelling in discrete fracture networks with connected and disconnected permeability fields. In SIAM. Erlangen, Germany.

Finsterle, S., & et al. (2017). Conceptual Uncertainties in Modelling the Interaction between Engineered and Natural Barriers. Presented at the Clay Conference 2017, Davos, Switzerland.

Frampton, A., Pannetier, R., Destouni, G. 2016. Mechanisms governing solute transport in the active layer of coupled permafrost-hydrogeological systems. Presented at the 11th International Conference on Permafrost, Potsdam, Germany.

Schuh, C., Frampton, A., Christiansen, H.H., 2016. Soil moisture redistribution and effect on active layer response to temperature variations in a dry loess terrace in Adventdalen, Svalbard. Presented at the 11th International Conference on Permafrost, Potsdam, Germany.

Pannetier, R., Frampton, A., 2016. Analysis of Flow Pathways and Transport Times in a Periglacial Permafrost Catchment near Kangerlussuaq, Greenland. Presented at the 11th International Conference on Permafrost, Potsdam, Germany.

Grenier, C., Anbergen, H., Bense, V., Coon, E., Collier, N., Costard, F., Ferry, M., Frampton, A., others, 2016. The InterFrost benchmark of Thermo-Hydraulic codes for cold regions hydrology – first intercomparison phase results. Presented at the 11th International Conference on Permafrost, Potsdam, Germany.

Frampton, A., Destouni, G., 2016. Solute transport modelling in a coupled water and heat flow system applied to cold regions hydrogeology, in: EGU General Assembly Conference Abstracts. p. 15497.

Frampton, A., 2016. Groundwater flow and solute transport modelling in coupled permafrost-hydrogeological systems. Presented at the 32nd Nordic Geological Winter Meeting, Helsinki, Finland.

Ströberg, A., Ebert, K., Jarsjö, J., Frampton, A., 2016. Contaminated area instability – the example of Ångerman River, northern Sweden. Presented at the 32nd Nordic Geological Winter Meeting, Helsinki, Finland.

Frampton, A., Pannetier, R., Destouni, G., 2015. Modelling groundwater transport and travel times in warming permafrost. Presented at the Grundvattendagarna, Sveriges Geologiska Undersökning, Göteborg, Sweden.

Grenier, et al., 2015. The InterFrost benchmark of Thermo-Hydraulic codes for cold regions hydrology – first inter-comparison results, in: Geophysical Research Abstracts. Presented at the EGU General Assembly, Vienna, 9723.

Pannetier, R., Frampton, A., 2015. Transient modeling of the hydro-thermal state of frozen ground in the sub-arctic catchment of Tarfala, Sweden., in: Geophysical Research Abstracts. Presented at the EGU General Assembly, Vienna, 11471.

Sjöberg, Y., Lyon, S., Pannetier, R., Coon, E., Harp, D., Frampton, A., Painter, S., 2015. Thermal effects from groundwater flow-A case study from a subarctic fen within the sporadic permafrost zone of Tavvavuoma, Sweden, in: Geophysical Research Abstracts. Presented at the EGU General Assembly, Vienna, 14029.

Frampton, A., 2015. Impact of thawing ground on subsurface water flow and transport in a modelled permafrost system, in: Geophysical Research Abstracts. Presented at the EGU General Assembly, Vienna, 11787.

Frampton, A., Destouni, G., Pannetier, R., 2014. Changes in travel times in thawing permafrost systems. Presented at the AGU Fall Meeting, San Francisco, C11C–0386.

Frampton, A., Destouni, G., 2014a. Modelling permafrost-induced hydrological change and associated changes in solute transport across scales, in: Geophysical Research Abstracts. Presented at the EGU General Assembly, Vienna, 10837.

Frampton, A., Destouni, G., 2014b. Impact of hydro‐climatic variability and change on travel time distributions in modelled active layer systems. Presented at the EUCOP4, Evora, Portugal, EUCOP4–0385.

Frampton, A., Destouni, G., 2013. Changes in subsurface water residence times under permafrost formation and degradation dynamics subject to hydro-climatic variability and change. Presented at the EGU General Assembly, Geophysical Research Abstracts, Vienna, EGU2013–5038.

Frampton, A., Painter, S.L., Destouni, G., 2012. Effects of hydrological inputs on the dynamics of permafrost system formation and degradation, in: Geophysical Research Abstracts. Presented at the EGU General Assembly, Vienna, EGU2012–5204–1.

Frampton, A., Cvetkovic, V., 2012. Modelling flow and transport in sparsely fractured rock using flow log data, in: International Association of Hydrogeologists. Presented at the Groundwater in Fractured Rocks Conference, Prague.

Frampton, A., 2012. Modelling groundwater flow in partially frozen media. Presented at the Hydro-Perm Workshop, Longyearbyen, Svalbard.

Frampton, A., Destouni, G., Sjoberg, Y., Painter, S., 2011. Transient modeling of permafrost dynamics in changing climate scenarios, in: E-Science, 2011 IEEE 7th International Conference. 113–118.

Frampton, A., Painter, S.L., Lyon, S.W., Sjöberg, Y., Destouni, G., 2011. Transient modeling of permafrost dynamics in a changing climate. Presented at the AGU Fall Meeting, San Francisco, C53G–02.

Frampton, A., Cvetkovic, V., 2011. Modelling sparsely fractured rock using flow log data. Presented at the Deep Hydrogeology Workshop, Department of Earth Sciences, Uppsala University, Sweden.

Frampton, A., Painter, S.L., Lyon, S.W., Destouni, G., 2011. Non-isothermal, three-phase simulations of near-surface flows in a model permafrost system under seasonal variability and climate change, in: Geophysical Research Abstracts. Presented at the EGU General Assembly, Vienna, EGU2011–8916.

 

 

Publikationer

I urval från Stockholms universitets publikationsdatabas

  • Impact of lateral groundwater flow on hydrothermal conditions of the active layer in a high-Arctic hillslope setting

    2021. Alexandra Hamm, Andrew Frampton. The Cryosphere 15 (10), 4853-4871

    Artikel

    Modeling the physical state of permafrost landscapes is a crucial addition to field observations in order to understand the feedback mechanisms between permafrost and the atmosphere within a warming climate. A common hypothesis in permafrost modeling is that vertical heat conduction is most relevant to derive subsurface temperatures. While this approach is mostly applicable to flat landscapes with little topography, landscapes with more topography are subject to lateral flow processes as well. With our study, we contribute to the growing body of evidence that lateral surface and subsurface processes can have a significant impact on permafrost temperatures and active layer properties. We use a numerical model to simulate two idealized hillslopes (a steep and a medium case) with inclinations that can be found in Adventdalen, Svalbard, and compare them to a flat control case. We find that ground temperatures within the active layer uphill are generally warmer than downhill in both slopes (with a difference of up to ∼0.8 ∘C in the steep and ∼0.6 ∘C in the medium slope). Further, the slopes are found to be warmer in the uphill section and colder in the base of the slopes compared to the flat control case. As a result, maximum thaw depth increases by about 5 cm from the flat (0.98 m) to the medium (1.03 m) and the steep slope (1.03 m). Uphill warming on the slopes is explained by overall lower heat capacity, additional energy gain through infiltration, and lower evaporation rates due to drier conditions caused by subsurface runoff. The major governing process causing the cooling on the downslope side is heat loss to the atmosphere through evaporation in summer and enhanced heat loss in winter due to wetter conditions and resulting increased thermal conductivity. On a catchment scale, these results suggest that temperature distributions in sloped terrain can vary considerably compared to flat terrain, which might impact the response of subsurface hydrothermal conditions to ongoing climate change.

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  • Wetlandscape size thresholds for ecosystem service delivery

    2020. Imenne Åhlén (et al.). Science of the Total Environment 704

    Artikel

    Wetlands are interconnected with the larger surrounding landscape through the hydrological cycling of water and waterborne substances. Therefore, the borders of individual wetlands may not be appropriate landscape system boundaries for understanding large-scale functions and ecosystem services of wetlandscapes (wetland network - landscape systems), and how these can be impacted by climate and land-use changes. Recognizing that such large-scale behaviours may not be easily predicted by simple extrapolation of individual wetland behaviours, we here investigate properties of 15 Swedish wetlandscapes in the extensive (22 650 km(2)) Norrstrom drainage basin (NDB) comprising as many as 1699 wetlands. Results based on wetland survey data in combination with GIS-based ecohydrological analyses showed that wetlands located in wetlandscapes above a certain size (in the NDB: similar to 250 km(2)) consistently formed networks with characteristics required to support key ecosystem services such as nutrient/pollutant retention and biodiversity support. This was in contrast to smaller wetlandscapes (<250 km(2)), which had smaller and less diverse wetlands with insufficient throughflow to significantly impact large-scale flows of water and nutrients/pollutants. The existence of such wetlandscape-size thresholds is consistent with scale-dependent flow accumulation patterns in catchments, suggesting likely transferability of this result also to other regions.

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  • Advective Transport in Discrete Fracture Networks With Connected and Disconnected Textures Representing Internal Aperture Variability

    2019. Andrew Frampton, J. D. Hyman, Liangchao Zou. Water resources research 55 (7), 5487-5501

    Artikel

    Flow and transport in three-dimensional discrete fracture networks with internal variability in aperture and permeability are investigated using a numerical model. The analysis is conducted for three different texture types representing internal variability considering various correlation lengths and for an increase in domain size corresponding to an increase in network complexity. Internal variability in discrete fracture networks generally increases median travel times and delays arrival of bulk mass transport when compared against reference cases without texture, corresponding to smooth fractures. In particular, internal variability textures with weak connectivity increase travel times nonlinearly with domain size increase, further delaying bulk mass arrival. Textures with strong connectivity can however decrease median travel times, accelerating bulk mass arrival, but only for limited ranges of correlation length and domain size. As domain size increases, travel times of textures with strong connectivity converge toward travel times obtained for classical multivariant Gaussian textures. Thus, accounting for internal fracture variability is potentially significant for improving conservative estimates of bulk mass arrival, flow channeling, and advective and reactive transport in large-scale discrete fracture networks. Further, early mass arrival can arrive significantly earlier for textures with strong connectivity and classical Gaussian textures corresponding to intermediate connectivity but are only slightly affected by textures with weak connectivity. Thus, accounting for internal variability in fractures is also important for accurate estimates of early solute mass arrival. The overall impact on predictive transport modeling will depend on the extent of, or lack of, internal fracture connectivity structure in real-world fractured rocks. Plain Language Summary This study investigates transport of waterborne substances in subsurface fractured bedrock, a topic which is of relevance to applications such as subsurface disposal of spent nuclear fuel, storage of carbon dioxide, and disposal of other hazardous material. A physically based numerical model for simulating water flow in the fractured bedrock system is used. Many model-based studies assume fractures to be smooth planes, which are an acknowledged simplification; however, real-world fractures are known to have rough surface asperities. In our study, we account for fracture roughness by assuming textures with different connectivity structure and investigate how this impacts waterborne transport in bedrock. We demonstrate that this type of fracture roughness can control important features of flow and waterborne mass transport. Specifically, most of the mass will generally arrive later than expected when compared to a smooth fracture plane assumption. However, we also observe that a small percentage of mass can, under certain circumstances, arrive earlier than what would be expected if smooth fracture planes are assumed. This means that the assumption of smooth fracture planes should generally be considered a conservative simplifying assumption in the context of subsurface storage, but it is less likely to be accurate when considering early mass arrival.

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  • Groundwater flow and heat transport for systems undergoing freeze-thaw

    2018. Christophe Grenier (et al.). Advances in Water Resources 114, 196-218

    Artikel

    In high-elevation, boreal and arctic regions, hydrological processes and associated water bodies can be strongly influenced by the distribution of permafrost. Recent field and modeling studies indicate that a fully-coupled multidimensional thermo-hydraulic approach is required to accurately model the evolution of these permafrost-impacted landscapes and groundwater systems. However, the relatively new and complex numerical codes being developed for coupled non-linear freeze-thaw systems require verification. This issue is addressed by means of an intercomparison of thirteen numerical codes for two-dimensional test cases with several performance metrics (PMs). These codes comprise a wide range of numerical approaches, spatial and temporal discretization strategies, and computational efficiencies. Results suggest that the codes provide robust results for the test cases considered and that minor discrepancies are explained by computational precision. However, larger discrepancies are observed for some PMs resulting from differences in the governing equations, discretization issues, or in the freezing curve used by some codes.

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  • Permafrost Map for Norway, Sweden and Finland

    2017. Kjersti Gisnås (et al.). Permafrost and Periglacial Processes 28 (2), 359-378

    Artikel

    A research-based understanding of permafrost distribution at a sufficient spatial resolution is important to meet the demands of science, education and society. We present a new permafrost map for Norway, Sweden and Finland that provides a more detailed and updated description of permafrost distribution in this area than previously available. We implemented the CryoGRID1 model at 1km(2) resolution, forced by a new operationally gridded data-set of daily air temperature and snow cover for Finland, Norway and Sweden. Hundred model realisations were run for each grid cell, based on statistical snow distributions, allowing for the representation of sub-grid variability of ground temperature. The new map indicates a total permafrost area (excluding palsas) of 23 400km(2) in equilibrium with the average 1981-2010 climate, corresponding to 2.2 per cent of the total land area. About 56 per cent of the area is in Norway, 35 per cent in Sweden and 9 per cent in Finland. The model results are thoroughly evaluated, both quantitatively and qualitatively, as a collaboration project including permafrost experts in the three countries. Observed ground temperatures from 25 boreholes are within +/- 2 degrees C of the average modelled grid cell ground temperature, and all are within the range of the modelled ground temperature for the corresponding grid cell. Qualitative model evaluation by field investigators within the three countries shows that the map reproduces the observed lower altitudinal limits of mountain permafrost and the distribution of lowland permafrost.

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  • Soil moisture redistribution and its effect on inter-annual active layer temperature and thickness variations in a dry loess terrace in Adventdalen, Svalbard

    2017. Carina Schuh, Andrew Frampton, Hanne Hvidtfeldt Christiansen. The Cryosphere 11 (1), 635-651

    Artikel

    High-resolution field data for the period 2000-2014 consisting of active layer and permafrost temperature, active layer soil moisture, and thaw depth progression from the UNISCALM research site in Adventdalen, Svalbard, is combined with a physically based coupled cryotic and hydrogeological model to investigate active layer dynamics. The site is a loess-covered river terrace characterized by dry conditions with little to no summer infiltration and an unsaturated active layer. A range of soil moisture characteristic curves consistent with loess sediments is considered and their effects on ice and moisture redistribution, heat flux, energy storage through latent heat transfer, and active layer thickness is investigated and quantified based on hydro-climatic site conditions. Results show that soil moisture retention characteristics exhibit notable control on ice distribution and circulation within the active layer through cryosuction and are subject to seasonal variability and site-specific surface temperature variations. The retention characteristics also impact unfrozen water and ice content in the permafrost. Although these effects lead to differences in thaw progression rates, the resulting inter-annual variability in active layer thickness is not large. Field data analysis reveals that variations in summer degree days do not notably affect the active layer thaw depths; instead, a cumulative winter degree day index is found to more significantly control inter-annual active layer thickness variation at this site. A tendency of increasing winter temperatures is found to cause a general warming of the subsurface down to 10m depth (0.05 to 0.26 degrees C yr(-1), observed and modelled) including an increas-ing active layer thickness (0.8 cm yr(-1), observed and 0.3 to 0.8 cm yr(-1), modelled) during the 14-year study period.

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  • Air warming trends linked to permafrost warming in the sub-Arctic catchment of Tarfala, Sweden

    2016. Romain Pannetier, Andrew Frampton. Polar Research 35

    Artikel

    Recent ground temperature records from the 100-m-deep borehole near the Tarfala Research Station in northern Sweden reveal that permafrost is warming at a pace consistent with the rate of measured air temperature increase at the site. Here we investigate whether air temperature increase is the main driver of the observed change in the permafrost thermal regime using a non-isothermal hydrogeological numerical model for partially frozen ground. The local site is investigated with different ground surface temperature scenarios representing different integrated effects of surficial heat attenuation processes. Results indicate that despite a short-term sensitivity to heat attenuation processes including snow conditions, the main driver of change in the permafrost thermal regime during the past decade is warming air temperatures. Additionally, the approach used here is shown to be particularly pertinent for modelling warming trends, despite limited prior knowledge of site-specific conditions and geological properties. Understanding the main driving mechanisms of changing permafrost is useful for assessing the suitability of borehole temperature records as proxies for past environmental conditions as well as for modelling possible future climatic impacts.

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  • Thermal effects of groundwater flow through subarctic fens

    2016. Ylva Sjöberg (et al.). Water resources research 52 (3), 1591-1606

    Artikel

    Modeling and observation of ground temperature dynamics are the main tools for understanding current permafrost thermal regimes and projecting future thaw. Until recently, most studies on permafrost have focused on vertical ground heat fluxes. Groundwater can transport heat in both lateral and vertical directions but its influence on ground temperatures at local scales in permafrost environments is not well understood. In this study we combine field observations from a subarctic fen in the sporadic permafrost zone with numerical simulations of coupled water and thermal fluxes. At the Tavvavuoma study site in northern Sweden, ground temperature profiles and groundwater levels were observed in boreholes. These observations were used to set up one- and two-dimensional simulations down to 2 m depth across a gradient of permafrost conditions within and surrounding the fen. Two-dimensional scenarios representing the fen under various hydraulic gradients were developed to quantify the influence of groundwater flow on ground temperature. Our observations suggest that lateral groundwater flow significantly affects ground temperatures. This is corroborated by modeling results that show seasonal ground ice melts 1 month earlier when a lateral groundwater flux is present. Further, although the thermal regime may be dominated by vertically conducted heat fluxes during most of the year, isolated high groundwater flow rate events such as the spring freshet are potentially important for ground temperatures. As sporadic permafrost environments often contain substantial portions of unfrozen ground with active groundwater flow paths, knowledge of this heat transport mechanism is important for understanding permafrost dynamics in these environments.

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  • Modeling early in situ wetting of a compacted bentonite buffer installed in low permeable crystalline bedrock

    2016. Benoît Dessirier (et al.). Water resources research 52 (8), 6207-6221

    Artikel

    The repository concept for geological disposal of spent nuclear fuel in Sweden and Finland is planned to be constructed in sparsely fractured crystalline bedrock and with an engineered bentonite buffer to embed the waste canisters. An important stage in such a deep repository is the postclosure phase following the deposition and the backfilling operations when the initially unsaturated buffer material gets hydrated by the groundwater delivered by the natural bedrock. We use numerical simulations to interpret observations on buffer wetting gathered during an in situ campaign, the Bentonite Rock Interaction Experiment, in which unsaturated bentonite columns were introduced into deposition holes in the floor of a 417 m deep tunnel at the Aspo Hard Rock Laboratory in Sweden. Our objectives are to assess the performance of state-of-the-art flow models in reproducing the buffer wetting process and to investigate to which extent dependable predictions of buffer wetting times and saturation patterns can be made based on information collected prior to buffer insertion. This would be important for preventing insertion into unsuitable bedrock environments. Field data and modeling results indicate the development of a de-saturated zone in the rock and show that in most cases, the presence or absence of fractures and flow heterogeneity are more important factors for correct wetting predictions than the total inflow. For instance, for an equal open-hole inflow value, homogeneous inflow yields much more rapid buffer wetting than cases where fractures are represented explicitly thus creating heterogeneous inflow distributions.

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  • Reconstruction of the water content at an interface between compacted bentonite blocks and fractured crystalline bedrock

    2017. Benoît Dessirier (et al.). Applied Clay Science 142, 145-152

    Artikel

    High-density sodium bentonite combines a low permeability with a swelling behavior, which constitute two important qualities for engineered barriers in geological disposal of spent nuclear fuel. For example, the KBS-3V method developed in Sweden and Finland is planned to include compacted bentonite as the buffer material to embed canisters containing the spent nuclear fuel packages in deposition holes in deep crystalline bedrock. The partially saturated bentonite buffer will then swell as it takes up groundwater from the surrounding rock. It is important to quantify the water content evolution of the installed buffer to correctly predict the development of the swelling pressure and the prevailing conditions (thermal, mechanical, chemical and biological). This study aimed at quantifying the water content profile at the surface of a cylindrical bentonite parcel retrieved after in situ wetting in fractured crystalline bedrock. We demonstrate the possibility of using regression-kriging to quantitatively include spatial information from high-resolution photographs of the retrieved bentonite parcel, where more water saturated areas appear as relatively dark shades, along with bentonite samples, where detailed measurements of water content were performed. The resulting reconstruction is both exact regarding local sample measurements and successful to reproduce features such as intersecting rock fracture traces, visible in the photographs. This level of detail is a key step to gain a deeper understanding of the hydraulic behavior of compacted bentonite barriers in sparsely fractured rock. An improved scanning procedure could further increase the accuracy by reducing errors introduced by the geometrical transformations needed to unfold and stitch the different photographs into a single gray scale map of the bentonite surface. The application of this technique could provide more insights to ongoing and planned experiments with unsaturated bentonite buffers.

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  • Impact of degrading permafrost on subsurface solute transport pathways and travel times

    2015. Andrew Frampton, Georgia Destouni. Water resources research 51 (9), 7680-7701

    Artikel

    Subsurface solute transport under surface warming and degrading permafrost conditions is studied using a physically based model of coupled cryotic and hydrogeological flow processes combined with a particle tracking method. Changes in the subsurface water and inert solute pathways and travel times are analyzed for different modeled geological configurations. For all simulated cases, the minimum and mean travel times increase nonlinearly with warming irrespective of geological configuration and heterogeneity structure. The timing of the start of increase in travel time depends on heterogeneity structure, combined with the rate of permafrost degradation that also depends on material thermal and hydrogeological properties. The travel time changes depend on combined warming effects of: i) increase in pathway length due to deepening of the active layer, ii) reduced transport velocities due to a shift from horizontal saturated groundwater flow near the surface to vertical water percolation deeper into the subsurface, and iii) pathway length increase and temporary immobilization caused by cryosuction-induced seasonal freeze cycles.

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  • Modeling Two-Phase-Flow Interactions across a Bentonite Clay and Fractured Rock Interface

    2014. Benoît Dessirier, Jerker Jarsjö, Andrew Frampton. Nuclear Technology 187 (2), 147-157

    Artikel

    Deep geological repositories are generally considered as suitable environments for final disposal of spent nuclear fuel. In the Swedish and Finnish repository design concept, canisters are to be placed in deep underground tunnels in sparsely fractured crystalline bedrock, in deposition holes in which each canister is embedded with an expansive bentonite-clay-mixture buffer. A set of semigeneric two-dimensional radially symmetric TOUGH2 simulations are conducted to investigate the multiphase dynamics and interactions between water and air in a bentonite-rock environment. The main objective is to identify how sensitive saturation times of bentonite are to the geometry of the rock fractures and to commonly adopted simplifications in the unsaturated flow description such as Richards assumptions. Results show that the location of the intersection between the fracture system and the deposition hole is a key factor affecting saturation times. A potential long-lasting desaturation of the rock matrix close to the bentonite-rock interface is also identified extending up to 10 cm inside the rock. Two-phase-flow models predict systematically longer saturation times compared to a simplified Richards approximation, which is frequently used to represent unsaturated flows. The discrepancy diverges considerably as full saturation is approached.

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  • A global sensitivity analysis of two-phase flow between fractured crystalline rock and bentonite with application to spent nuclear fuel disposal

    2015. Benoît Dessirier, Andrew Frampton, Jerker Jarsjö. Journal of Contaminant Hydrology 182, 25-35

    Artikel

    Geological disposal of spent nuclear fuel in deep crystalline rock is investigated as a possible long term solution in Sweden and Finland. The fuel rods would be cased in copper canisters and deposited in vertical holes in the floor of deep underground tunnels, embedded within an engineered bentonite buffer. Recent experiments at the Äspö Hard Rock Laboratory (Sweden) showed that the high suction of unsaturated bentonite causes a de-saturation of the adjacent rock at the time of installation, which was also independently predicted in model experiments. Remaining air can affect the flow patterns and alter bio-geochemical conditions, influencing for instance the transport of radionuclides in the case of canister failure. However, thus far, observations and model realizations are limited in number and do not capture the conceivable range and combination of parameter values and boundary conditions that are relevant for the thousands of deposition holes envisioned in an operational final repository.

    In order to decrease this knowledge gap, we introduce here a formalized, systematic and fully integrated approach to study the combined impact of multiple factors on air saturation and dissolution predictions, investigating the impact of variability in parameter values, geometry and boundary conditions on bentonite buffer saturation times and on occurrences of rock de-saturation. Results showed that four parameters consistently appear in the top six influential factors for all considered output (target) variables: the position of the fracture intersecting the deposition hole, the background rock permeability, the suction representing the relative humidity in the open tunnel and the far field pressure value. The combined influence of these compared to the other parameters increases as one targets a larger fraction of the buffer reaching near-saturation. Strong interaction effects were found, which means that some parameter combinations yielded results (e.g., time to saturation) far outside the range of results obtained by the rest of the scenarios. This study also addresses potential air trapping by dissolution of part of the initial air content of the bentonite, showing that neglecting gas flow effects and trapping could lead to significant underestimation of the remaining air content and the duration of the initial aerobic phase of the repository.

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  • Permafrost degradation and subsurface-flow changes caused by surface warming trends

    2012. Andrew Frampton, Scott L. Painter, Georgia Destouni. Hydrogeology Journal 21 (1), 271-280

    Artikel

    Change dynamics of permafrost thaw, andassociated changes in subsurface flow and seepage into surface water, are analysed for different warming trends in soil temperature at the ground surface with a three-phase two-component flow system coupled to heat transport. Changes in annual, seasonal and extreme flows are analysed for three warming-temperature trends, representing simplified climate change scenarios. The results support previous studies of reduced temporal variability of groundwater flow across all investigated trends. Decreased intra-annual flow variability may thus serve asan early indicator of permafrost degradation before longer term changes in mean flows are notable. This is advantageous since hydrological data are considerably easier to obtain, may be available in longer time series, and generally reflect larger-scale conditions than direct permafrost observations. The results further show that permafrost degradation first leads to increasing water discharge, which then decreases as the permafrost degradation progresses further to total thaw. The most pronounced changes occur for minimum annual flows. The configuration considered represents subsurface discharge from a generic heterogeneous soil-type domain.

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  • Solute transport and retention in three-dimensional fracture networks

    2012. Vladimir Cvetkovic, Andrew Frampton. Water resources research 48, W02509

    Artikel

    Resolving the hydrodynamic control of retention is an important step in predictive modeling of transport of sorbing tracers in fractured rock. The statistics of the transport resistance parameter beta [T/L] and the related effective active specific surface area s(f) [1/L] are studied in a crystalline rock volume on a 100 m scale. Groundwater flow and advective transport are based on generic boundary conditions and realistic discrete fracture networks inferred from the Laxemar site, southeast Sweden. The overall statistics of beta are consistent with statistics of the water residence time tau; the moments of beta vary linearly with distance, at least up to 100 m. The correlation between log tau and log beta is predominantly linear, however, there is significant dispersion; the parameter s(f) strongly depends on the assumed hydraulic law (theoretical cubic or empirical quadratic). Fast and slow trajectories/segments in the network determine the shape of the beta distribution that cannot be reproduced by infinitely divisible model over the entire range; the low value range and median can be reproduced reasonably well with the tempered one-sided stable density using the exponent in the range 0.35-0.7. The low percentiles of the beta distribution seems to converge to a Fickian type of behavior from a 50 to 100 m scale.

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  • Using streamflow characteristics to explore permafrost thawing in northern Swedish catchments

    2012. Ylva Sjöberg, Andrew Frampton, Steve W. Lyon. Hydrogeology Journal 21 (1), 121-131

    Artikel

    The recent and rapid warming of the Arcticleads to thawing of permafrost, which influences andchanges subsurface water-flow systems in such landscapes.This study explores the utility of catchments as“sentinels of change” by considering long-term dischargedata from 17 stations on unregulated rivers in northernSweden and analyzing trends in annual minimum dischargeand recession flow characteristics. For the catchmentsconsidered, the annual minimum discharge hasincreased significantly (based on the Mann Kendall test ata 95% confidence level) in nine of the catchments anddecreased significantly in one catchment. Consideringchanges in recession-flow characteristics, seven catchmentsshowed significant trends consistent with permafrostthawing while two catchments showed significanttrends in the opposite direction. These results aremechanistically consistent with generic physically basedmodeling studies and the geological setting, as thecatchments considered span the spatial limit of permafrostextent. This study illuminates the potential for usinghydrologic observations to monitor changes in catchmentscalepermafrost. Further, this opens the door for researchto isolate the mechanisms behind the different trendsobserved and to gauge their ability to reflect actualpermafrost conditions at the catchment scale.

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  • Non-isothermal, three-phase simulations of near-surface flows in a model permafrost system under seasonal variability and climate change

    2011. Andrew Frampton (et al.). Journal of Hydrology 403 (3-4), 352-359

    Artikel

    Permafrost responses to a changing climate can affect hydrological and biogeochemical cycling, ecosystems and climate feedbacks. We have simulated a model permafrost system in the temperature range associated with discontinuous permafrost focusing on interactions between permafrost and hydrology using a non-isothermal, three-phase model of water migration coupled to heat transport in partially frozen porous media. We explore the subsurface hydraulic property controls on the formation and dynamics of permafrost, and how this impacts seasonal variability of subsurface runoff to surface waters. For all subsurface conditions considered, the main common hydrological signal of permafrost degradation in a warming trend is decreasing seasonal variability of water flow. This is due to deeper and longer flow pathways with increasing lag times from infiltration or thawing through subsurface flow to surface water discharge. These results show how physically based numerical modelling can be used to quantitatively and qualitatively improve the understanding of how permafrost thawing relates to, and may be detected in, hydrological data. This is advantageous since hydrological data is considerably easier to obtain, may be available in longer time series, and generally reflects larger-scale conditions than direct permafrost observations.

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  • Numerical and analytical modeling of advective travel times in realistic three-dimensional fracture networks

    2011. Andrew Frampton, Vladimir Cvetkovic. Water resources research 47, W02506

    Artikel

    Travel time distributions obtained from advective transport in multiple realizations of realistic discrete fracture network simulations are analyzed using the truncated one-sided stable distribution, which has previously been shown to generalize both the advectiondispersion solution as well as one-sided stable distributions. Using this model, it is shown that the Fickian assumption inherent in the advection-dispersion equation generally fails, despite the first two moments of travel time essentially scaling linearly with distance. It is also observed that the equally probable realizations drawn from the ensemble can produce a wide range of behavior under the current configuration, such that Fickian conditions are almost obtained in some cases for increasing scales. On the basis of a small-scale calibration against particle breakthrough, the model is then shown to successfully predict limiting bounds of transport for a one order of magnitude increase in scale. Correlation in particle velocity is explicitly shown to be significant for scales close to the characteristic Lagrangian segment length. The network configuration is obtained from extensive site characterization data at the Laxemar region in Sweden and represents a block-scale domain of reasonably sparse background fractures.

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  • Transport and retention from single to multiple fractures in crystalline rock at Aspo (Sweden)

    2010. V. Cvetkovic, A. Frampton. Water resources research 46, W05506

    Artikel

    Hydrogeologic characterization of crystalline rock formations on the field scale is important for many applications but still presents a multitude of challenges. In this work we use comprehensive hydrostructural information and present a detailed simulation study of flow and advective transport in a discrete fracture network (DFN) that replicates the Tracer Retention Understanding Experiments (TRUE) Block Scale rock volume at the Aspo Hard Rock Laboratory (Sweden). Simulated water residence time tau and hydrodynamic retention parameter beta are used as independent constraints for estimating material retention properties as presented in paper 1 of this series, whereas simulated mean water residence times are compared with observed values. We find that the DFN simulations reproduce water residence times reasonably well, indicating that the characterization data are sufficient and that the DFN model does capture dominant features of the flow paths analyzed. The empirical quadratic law that relates aperture and transmissivity seems to better reproduce calibrated mean water residence times than the theoretical cubic law for the five flow paths. The active specific surface area (beta/tau) [1/L] as inferred from simulations is used for defining a generic retention model for the dominant rock type (Aspo diorite) that matches fairly well the entire range of calibrated retention parameters of the TRUE tests. The combination of paper 1 and this work provides a general, comprehensive methodology for evaluating tracer test results in crystalline rock where a comparable amount of information is available; critical to this methodology is that tracer tests are carried out using tracers with sufficiently different sorption affinities (of factor 10-100).

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