Estimating plume degradation rates in aquifers: Effect of propagating measurement and methodological errors

Jarsjö, Jerker; Bayer‐Raich, Martí

doi:10.1029/2006wr005568

Cited by 15 publications

(11 citation statements)

References 20 publications

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“…The interval may widen significantly if also the attenuation rate λ is variable, and depending on its possible cross-correlation with the advective travel time T [e.g., 34,[64][65][66]. Further investigations and realistic quantifications are needed for the spatial variability of biogeochemical attenuation rates and their correlation with the physics of flow and transport in both the surface water and not least the groundwater systems of hydrological catchments.…”

Section: Resultsmentioning

confidence: 98%

Quantification of advective solute travel times and mass transport through hydrological catchments

et al. 2009

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This study has investigated and outlined the possible quantification and mapping of the distributions of advective solute travel times through hydrological catchments. These distributions are essential for understanding how local water flow and solute transport and attenuation processes affect the catchment-scale transport of solute, for instance with regard to biogeochemical cycling, contamination persistence and water quality. The spatial and statistical distributions of advective travel times have been quantified based on reported hydrological flow and mass-transport modeling results for two coastal Swedish catchments. The results show that the combined travel time distributions for the groundwater-stream network continuum in these catchments depend largely on the groundwater system and model representation, in particular regarding the spatial variability of groundwater hydraulic parameters (conductivity, porosity and gradient), and the possible contributions of slower/deeper groundwater flow components. Model assumptions about the spatial variability of groundwater hydraulic properties can thus greatly affect model results of catchment-scale solute spreading. The importance of advective travel time variability for the total mass delivery of naturally attenuated solute (tracer, nutrient, pollutant) from a catchment to its downstream water recipient depends on the product of catchment-average physical travel time and attenuation rate.

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Section: Resultsmentioning

confidence: 98%

Quantification of advective solute travel times and mass transport through hydrological catchments

et al. 2009

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“…Malmström et al, 2004Malmström et al, , 2008Darracq and Destouni, 2007;Cunningham and Fadel, 2007;Jardine, 2008) -the errors of mass transport measurements implied by the chosen measurement methods and the coverage gaps between the chosen measurement points in time and space (e.g. Hannerz and Destouni, 2006;Beven, 2006;Jarsjö and Bayer-Raich, 2008;Destouni et al, 2008) -the chosen model resolutions and possible neglect of potentially important contributing mass transport processes at different scales (e.g. Lindgren and Destouni, 2004;Refsgaard et al, 2006;Destouni et al, 2006;Ganoulis, 2009).…”

Section: Introductionmentioning

confidence: 99%

Diffuse hydrological mass transport through catchments: scenario analysis of coupled physical and biogeochemical uncertainty effects

Persson

Jarsjö

2011

Hydrol. Earth Syst. Sci.

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Abstract. This paper quantifies and maps the effects of coupled physical and biogeochemical variability on diffuse hydrological mass transport through and from catchments. It further develops a scenario analysis approach and investigates its applicability for handling uncertainties about both physical and biogeochemical variability and their different possible cross-correlation. The approach enables identification of conservative assumptions, uncertainty ranges, as well as pollutant/nutrient release locations and situations for which further investigations are most needed in order to reduce the most important uncertainty effects. The present scenario results provide different statistical and geographic distributions of advective travel times for diffuse hydrological mass transport. The geographic mapping can be used to identify potential hotspot areas with large mass loading to downstream surface and coastal waters, as well as their opposite, potential lowest-impact areas within the catchment. Results for alternative travel time distributions show that neglect or underestimation of the physical advection variability, and in particular of those transport pathways with much shorter than average advective solute travel times, can lead to substantial underestimation of pollutant and nutrient loads to downstream surface and coastal waters. This is particularly true for relatively high catchment-characteristic product of average attenuation rate and average advective travel time, for which mass delivery would be near zero under assumed transport homogeneity but can be orders of magnitude higher for variable transport conditions. A scenario of high advection variability, with a significant fraction of relatively short travel times, combined with a relevant average Correspondence to: K. Persson (klas.persson@natgeo.su.se) biogeochemical mass attenuation rate, emerges consistently from the present results as a generally reasonable, conservative assumption for estimating maximum diffuse mass loading, when the prevailing physical and biogeochemical variability and cross-correlation are uncertain.

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“…Furthermore, Jarsjö and Bayer‐Raich [2008] showed that the relative errors ɛ c in C av due to neglecting λ (assuming λ = 0 in degrading plumes) remain small for small capture zones ( r c ( t ) < 10 m) considering a degradation value range of δ = λ / u 0,w that has been observed in the field. For larger capture zones, the error may increase and the assumption λ = 0 can (under some conditions [ Jarsjö and Bayer‐Raich , 2008]) result in overestimation of C av . For instance, for values of κ = λr c ( t )/ u 0, w < 2, relative errors in C av remain within ɛ c < 1, while, e.g., κ > 3 yield relative errors ɛ c > 2.5.…”

Section: Inverse Problem For Homogeneous Aquifers: General Formulatiomentioning

confidence: 84%

“…The inverse solutions demonstrate that for relatively short pumping tests, where t ≪ RQn e /( bq 0, w 2 ), estimated C av values (given a measured C p ( t )) are not very sensitive to plume degradation (i.e., accurate C av estimates will be obtained, even if λ = 0 is assumed for degrading plumes), as long as κ = λr c ( t )/ u 0, w < 2. For higher values of κ, C av will generally be overestimated, if plume degradation is neglected; however λ can in such cases be determined independently in situ using multiple control planes [see Bayer‐Raich et al , 2006; Jarsjö and Bayer‐Raich , 2008].…”

Section: Discussionmentioning

confidence: 99%

“…The work presented here is a generalization of the analytical framework given by Bayer‐Raich et al [2004a, 2004b, 2006] and Jarsjö and Bayer‐Raich [2008] for consideration of first‐order (bio‐)degradation. In addition to quantitative and generic insights on contaminant transport in the near vicinity of pumping wells, the developments presented here enable for the first time IPT assessments of nonideal contaminants (i.e., that degrade over the capture zone extent such as BTEX compounds can do) without formal violation of underlying theoretical assumptions, and provide a basis for conducting sensitivity analyses of degradation and sorption parameter uncertainties.…”

Section: Introduction and Statement Of The Problemmentioning

confidence: 99%

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Breakthrough of attenuating contaminant plumes in pumping wells: Analytical model and implications for integral pumping tests

Bayer‐Raich

Jarsjö

Teutsch

2009

Water Resources Research

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[1] Monitoring of contaminant plumes and predicting their future fate are essential for effective management of groundwater contaminants. Solute breakthrough curves from operating pumping wells can provide information on the water quality in relatively large aquifer regions, which may be unavailable to instrumentation and direct measurement for practical and/or economical reasons. Relations between spatially varying aquifer concentrations C 0 (x, y) initially surrounding a well and temporally varying concentrations of subsequently extracted well water, C p (t), then need to be quantified. However, limited applicability of analytical expressions and numerical inaccuracies related to solving transport equations for converging flow fields hamper such quantifications even in homogeneous aquifers. We use a stream-tube approach and provide a general problem formulation that accounts for first-order degradation and linear, instantaneous, sorption/retardation in heterogeneous aquifers. An analytical expression is obtained for homogeneous aquifer conditions (in the well vicinity), relating any given initial C 0 (x, y) function and the subsequent contaminant breakthrough C p (t) in the well. Results for wide plumes subject to first-order degradation show that concentrations at the extraction well will increase as a function of pumping time. This increase is despite the fact that late-time data reflect longer transport paths (to the well), along which mass is removed through degradation. We also derive unique solutions for the inverse problem, in particular considering how the average contaminant concentration C av (averaged along a control plane through the well within its capture zone, perpendicular to the mean groundwater flow direction) depends on the measurable C p (t). The solutions demonstrate that the longer the pumping time, the more sensitive the solutions for C av become to degradation rate constants, which if needed can be determined in situ using multiple control planes.

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Estimating plume degradation rates in aquifers: Effect of propagating measurement and methodological errors

Cited by 15 publications

References 20 publications

Quantification of advective solute travel times and mass transport through hydrological catchments

Quantification of advective solute travel times and mass transport through hydrological catchments

Diffuse hydrological mass transport through catchments: scenario analysis of coupled physical and biogeochemical uncertainty effects

Breakthrough of attenuating contaminant plumes in pumping wells: Analytical model and implications for integral pumping tests

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