Multiscale hyporheic exchange through strongly heterogeneous sediments

Pryshlak, Timothy T.; Sawyer, Audrey H.; Stonedahl, S. H.; Soltanian, Mohamad Reza

doi:10.1002/2015wr017293

Cited by 82 publications

(77 citation statements)

References 68 publications

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“…Streambed heterogeneity is expected to affect hyporheic exchange fluxes, flow paths, and solute residence times in the streambed due to the physical structure of the sediments [ Gomez‐Velez et al ., ; Pryshlak et al ., ]. Heterogeneous structures in streambeds are formed as a result of the transport and settling processes of particles in streams, which occur over a wide range of flow conditions [ Powell , ].…”

Section: Introductionmentioning

confidence: 99%

The effect of losing and gaining flow conditions on hyporheic exchange in heterogeneous streambeds

Fox

Laube

Schmidt

et al. 2016

Water Resources Research

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Bed form‐induced hyporheic exchange flux (qH) is increasingly viewed as a key process controlling water fluxes and biogeochemical processes in river networks. Despite the fact that streambeds are inherently heterogeneous, the majority of bed form flume‐scale studies were done on homogeneous systems. We conducted salt and dye tracer experiments to study the effects of losing and gaining flow conditions on qH using a laboratory recirculating flume system packed with a heterogeneous streambed, and equipped with a drainage system that enabled us to apply losing or gaining fluxes. We found that when either losing or gaining fluxes increased (regardless of whether the flux was upward or downward), qH followed an exponential decline, the volume of the hyporheic flow cell drastically reduced, and the mean residence times declined moderately. A numerical flow model for the heterogeneous streambed was set up and fitted against the experimental data in order to test whether an equivalent homogeneous case exists. The measured qH were accurately predicted with the heterogeneous model, while it was underestimated using a homogeneous model characterized by the geometric mean of the hydraulic conductivity. It was also shown that in order to produce the results of the heterogeneous model with an equivalent hydraulic conductivity, the latter had to be increased as the losing or gaining fluxes increase. The results strongly suggest that it is critical to adequately account for the heterogeneous streambed structure in order to accurately predict the effect of vertical exchange fluxes between the stream and groundwater on hyporheic exchange.

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Section: Introductionmentioning

confidence: 99%

The effect of losing and gaining flow conditions on hyporheic exchange in heterogeneous streambeds

Fox

Laube

Schmidt

et al. 2016

Water Resources Research

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“…This is consistent with our simulation results, which address a two‐phase flow problem and a more complex system in terms of heterogeneity arising from facies architecture. Fluvial depositional systems clearly have a dramatic impact on solute transport in the subsurface in both single and multiphase flow problems because the preferential pathways account for the majority of mass transport . Recently, Kilgallon et al .…”

Section: Resultsmentioning

confidence: 99%

Transport of perfluorocarbon tracers in the Cranfield Geological Carbon Sequestration Project

et al. 2018

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A field‐scale carbon dioxide (CO2) injection pilot project was conducted by the Southeast Regional Carbon Sequestration Partnership (SECARB) at Cranfield, Mississippi. Two associated campaigns in 2009 and 2010 were carried out to co‐inject perfluorocarbon tracers (PFTs) and sulfur hexafluoride (SF6) with CO2. Tracers in gas samples from two observation wells were analyzed to construct breakthrough curves. In this work, we present the field data and numerical modeling of the flow and transport of CO2, brine, and tracers. A high‐resolution static model of the formation geology in the detailed area study (DAS) was used to capture the impact of connected flow pathways created by fluvial channels on breakthrough curves and breakthrough times of PFTs and SF6 tracers. We use the cubic‐plus‐association (CPA) equation of state, which takes into account the polar nature of water molecules, to describe the phase behavior of CO2–brine‐tracer mixtures. Our simulated results show good agreement for the 2009 tracer campaign in Cranfield, while a larger discrepancy emerges by 2010. The combination of multiple tracer injection pulses with detailed numerical simulations proves to be a powerful tool in constraining both formation properties and how complex flow paths develop over time. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd.

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“…Our numerical experiments yielded a number of interesting results, some of which corroborate previous research findings while others lead to new hypotheses and suggest important avenues for future work. It is fairly well established that using homogenous arithmetic or geometric permeability values to model systems with heterogeneous sediments is problematic in hyporheic studies (Pryshlak et al ; Fox et al ) as well as the broader hydrogeology literature (De Wit ; De Marsily et al ; Masihi et al ). Our 900 simulations of varied sediment arrangements within a controlled environment highlight just how much error can result.…”

Section: Discussion/conclusionmentioning

confidence: 99%

“…Hester et al () found that hyporheic zones increased in size when heterogeneity was included. In a reach‐scale numerical study, Pryshlak et al () investigated different discontinuous permeability distributions, but the length scale of discontinuities was generally much smaller than the dominant ripple features. A few permeability studies have been conducted using controlled physical systems at a flume scale to investigate the effect of permeability structure (Salehin et al ) and layers (Marion et al ) on hyporheic flow.…”

Section: Introductionmentioning

confidence: 99%

Effect of Heterogeneous Sediment Distributions on Hyporheic Flow in Physical and Numerical Models

Stonedahl¹,

Sawyer

Stonedahl

et al. 2018

Groundwater

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Variations in permeability have been found to significantly affect the flow of water though hyporheic systems, especially in regions with discontinuous transitions between distinct streambed lithologies. In this study, we probabilistically arranged two sediments (sand and sandy gravel) in a grid framework and imposed a single hyporheic flow cell across the grid to investigate how discontinuous permeability fields influence volumetric flow and residence time distributions. We used both a physical system and computer simulations to model flow through this sediment grid. A solution of blue dye and salt was pumped into the system and used to detect flow. We recorded the dye location using time-lapse photography and measured the electrolytic conductivity levels as the water exited the system as a proxy for salt concentration. We also used a computer simulation to calculate dye-fronts, residence times, and exiting salt concentrations for the modeled system. Comparison between simulations and physical measurements yielded strong agreement. In further simulations with 300 different grids, we found a strong correlation between volumetric flow rate and the placement of high permeability grid cells in regions of high hydraulic head gradients. One implication is that small anomalies in streambed permeability have a disproportionately large influence on hyporheic flows when located near steep head gradients such as steps. We also used moving averages with varying window sizes to investigate the effect of the abruptness of transitions between sediment types. We found that smoother permeability fields increased the volumetric flow rate and decreased the median residence times.

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Multiscale hyporheic exchange through strongly heterogeneous sediments

Cited by 82 publications

References 68 publications

The effect of losing and gaining flow conditions on hyporheic exchange in heterogeneous streambeds

The effect of losing and gaining flow conditions on hyporheic exchange in heterogeneous streambeds

Transport of perfluorocarbon tracers in the Cranfield Geological Carbon Sequestration Project

Effect of Heterogeneous Sediment Distributions on Hyporheic Flow in Physical and Numerical Models

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