Spatial and temporal dynamics of coupled groundwater and nitrogen fluxes through a streambed in an agricultural watershed

Kennedy, Casey D.; Genereux, David P.; Corbett, D. Reide; Mitášová, Helena

doi:10.1029/2008wr007397

Cited by 81 publications

(144 citation statements)

References 67 publications

(95 reference statements)

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“…Sun and Zhan (2007) noted that one of the most important factors controlling the interaction of an aquifer with two parallel streams is the hydraulic conductivity ratio of the two streambeds, especially when a low-K streambed exists. Heterogeneity of streambed K could affect hyporheic zone fluxes and groundwater discharge (Salehin et al 2004;Kalbus et al 2009;Kennedy et al 2009). Also, hyporheic exchange at channel surface affects the distribution of streambed K v such that streambed K v in the upper sediment layer is higher than that in the lower sediment layer (Song et al 2007).…”

Section: Introductionmentioning

confidence: 99%

“…A number of researchers discussed the methods for the determination of streambed K, which include the permeameter test (Hvorslev 1951;Chen 2000Chen , 2004Chen , 2005Landon et al 2001;Genereux et al 2008;Kennedy et al 2009), slug and bail tests (Springer et al 1999;Landon et al 2001;Ryan and Boufadel 2007;Leek et al 2009), grain-size analysis (Chen 2000;Landon et al 2001), and pumping test (Kelly and Murdoch 2003). Generally slug and bail tests can only provide streambed horizontal hydraulic conductivity (K h ) values, while grain-size analysis cannot evaluate the anisotropy of K values because the sediment structure is destroyed during sampling (Chen 2000;Kalbus et al 2006;Cheng and Chen 2007).…”

Section: Introductionmentioning

confidence: 99%

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Statistical Distribution of Streambed Vertical Hydraulic Conductivity along the Platte River, Nebraska

Cheng

Song

Chen

et al. 2010

Water Resour Manage

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Streambed vertical hydraulic conductivity (K v ) plays an important role in understanding and quantifying the stream-aquifer interactions. While several researchers have discussed the spatial variability of streambed horizontal hydraulic conductivity or K v at one or several close-located sites in a river, they did not develop any statistical distribution analysis of streambed K v at distant sites along a large river. In this paper, the statistical distribution and spatial variation of streambed K v at 18 test sites in a 300-km reach of the Platte River in Nebraska are presented. Insitu permeameter tests using the falling-head method were carried out to calculate the streambed K v values. Fine-grained sediments transported by two tributaries, the Loup River and the Elkhorn River, to the Platte River appear to result in lower streambed K v values downstream of the confluences between the Platte River and the tributaries. The streambed K v values were found to be normally distributed at nearly each test site. When the correlated K v values were eliminated from the grid sampling plots, the remaining independent sub-datasets of streambed K v values were still in normal distribution at each test site. Furthermore, the combined streambed K v values upstream of the first confluence between the Platte River and the Loup River was normally distributed, which may be due to the lack of tributaries in-between and thus streambed sediments were well distributed in this reach and belonged to a single population of hydraulic conductivity values. In contrast, the combined dataset of all measurements conducted downstream of this confluence was no longer in normal distribution, presumably as a result of the mixing of different sediment sources.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Statistical Distribution of Streambed Vertical Hydraulic Conductivity along the Platte River, Nebraska

Cheng

Song

Chen

et al. 2010

Water Resour Manage

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“…Nonetheless, they were able to relate the observed heterogeneity in physical properties to predictions based on knowledge of sedimentary processes and streambed structure. Although spatial variations in streambed topography (Rosenberry and Pitlick, 2009) and hydraulic gradient (Kennedy et al , 2009) influence the distribution of groundwater flux through streambeds, water fluxes in gaining streams are generally most strongly influenced by hydraulic conductivity of the bed sediments (Conant et al , 2004; Kennedy et al , 2009).…”

Section: Introductionmentioning

confidence: 99%

Travel time controls the magnitude of nitrate discharge in groundwater bypassing the riparian zone to a stream on Virginia's coastal plain

Flewelling

Herman

Hornberger

et al. 2011

Hydrological Processes

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Abstract:Groundwater that bypasses the riparian zone by travelling along deep flow paths may deliver high concentrations of fertilizerderived NO 3 to streams, or it may be impacted by the NO 3 removal process of denitrification in streambed sediments. In a study of a small agricultural catchment on the Atlantic coastal plain of Virginia's eastern shore, we used seepage meters deployed in the streambed to measure specific discharge of groundwater and its solute concentrations for various locations and dates. We used values of Cl concentration to discriminate between bypass water recharged distal to the stream and that contained high NO 3 but low Cl concentrations and riparian-influenced water recharged proximal to the stream that contained low NO 3 and high Cl concentrations. The travel time required for bypass water to transit the 30-cm-thick, microbially active denitrifying zone in the streambed determined the extent of NO 3 removal, and hydraulic conductivity determined travel time through the streambed sediments. At all travel times greater than 2 days, NO 3 removal was virtually complete. Comparison of the timescales for reaction and transport through the streambed sediments in this system confirmed that the predominant control on nitrate flux was travel time rather than denitrification rate coefficients. We conclude that extensive denitrification can occur in groundwater that bypasses the riparian zone, but a residence time in biologically active streambed sediments sufficient to remove a large fraction of the NO 3 is only achieved in relatively low-conductivity porous media. Instead of viewing them as separate, the streambed and riparian zone should be considered an integrated NO 3 removal unit.

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“…This entails a minimum understanding of processes and rates influencing the concentrations. The temporal variability in nitrate concentrations in groundwater are related to the flow rate rather than seasonal changes (Kennedy et al, 2009). The same was observed for phosphorus, where particularly dry periods followed by heavy rain increases the phosphorus concentration measured in groundwater-fed springs (Kilroy and Coxon, 2005).…”

Section: Tracer Influences 300mentioning

confidence: 99%

Catchment tracers reveal discharge, recharge and sources of groundwater-borne pollutants in a novel lake modelling approach

Kristensen¹,

Madsen-Østerbye²,

Massicotte³

et al. 2017

Preprint

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Abstract.Groundwater borne contaminants such as e.g., nutrients, dissolved organic carbon (DOC), coloured dissolved organic matter 10 (CDOM) and pesticides impact the biological quality of lakes. The sources of pollution can, however, be difficult to identify due to high heterogeneity in groundwater flow patterns. This study presents a novel approach for fast hydrological surveys of small groundwater-fed lakes using multiple groundwater-borne tracers. Water samples were collected from groundwater wells installed every 50 m within 5-45 m from the shore and were analysed for tracer concentrations of CDOM, DOC, total dissolved nitrogen (TDN), total dissolved phosphorus (TDP), 18 O isotopes and fluorescent dissolved organic matter 15 (FDOM) components derived from parallel factor analysis (PARAFAC). Based on tracer concentrations and degradation rates, the maximum WRT was estimated to 2 years. Isolation of groundwater recharge areas were based on 18 O measurements and sites with high a degree of recharge was isolated using PARAFAC component C4. Groundwater discharge sites and the fractions of water delivered from the sites were isolated with the Community Assembly via Trait Selection model (CATS) for WRTs between 0.25 and 2 years. The identified recharge sites corresponded to areas adjacent to 20 drainage channels and a cluster analysis of component C4 further identified five sites which showed a tendency of high groundwater recharge rates. Isolated groundwater discharge sites were located in the eastern part of the lake and a single site in the southern part. Observations from the eastern part of the lake revealed an impermeable clay layer that promotes discharge during short precipitation events, which would be difficult to identify using traditional hydrological methods. High tracer concentrations in the southern part in relation to lake concentrations showed that only a smaller fraction of water could 25 originate from this area, thereby confirming the model results. The methodology used can be applied to smaller lakes yielding results within a short time frame with information related to the WRT of the lake.

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Spatial and temporal dynamics of coupled groundwater and nitrogen fluxes through a streambed in an agricultural watershed

Cited by 81 publications

References 67 publications

Statistical Distribution of Streambed Vertical Hydraulic Conductivity along the Platte River, Nebraska

Statistical Distribution of Streambed Vertical Hydraulic Conductivity along the Platte River, Nebraska

Travel time controls the magnitude of nitrate discharge in groundwater bypassing the riparian zone to a stream on Virginia's coastal plain

Catchment tracers reveal discharge, recharge and sources of groundwater-borne pollutants in a novel lake modelling approach

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