Groundwater flow path dynamics and nitrogen transport potential in the riparian zone of an agricultural headwater catchment

Williams, Mark R.; Buda, Anthony R.; Elliott, Herschel A.; Hamlett, J. M.; Boyer, E. W.; Schmidt, John P.

doi:10.1016/j.jhydrol.2014.02.033

Cited by 47 publications

(56 citation statements)

References 43 publications

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“…A framework to select species for N management would optimally be applied overlying an understanding of hydrological flow paths in riparian zones, as this governs the ability of plants to interact with N and influence its retention (Williams et al . ). For example, when N is flowing in deep subsurface layers of the riparian zone, deep rooting species (e.g.…”

Section: Discussionmentioning

confidence: 97%

Plants for nitrogen management in riparian zones: A proposed trait‐based framework to select effective species

Franklin¹,

Robinson²,

Dickinson³

2019

Eco Management Restoration

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Summary Restoring plants to the riparian zone is regarded as management best practice in river restoration and has the potential to reduce the impact of nitrogen (N) pollution on aquatic organisms and improve water quality for human use. Plant characteristics and the interplay of hydrology and biogeochemistry control N retention in the riparian zone. The balance between processes such as denitrification and plant assimilation determines riparian N retention. Plant traits are likely to mediate these N removal processes through variations in root form, growth character, foliage production (quantity, quality and rate of return to the soil) and by altering conditions in the rhizosphere soil. Vegetation can slow N transfer via direct plant uptake of N (during periods of rapid vegetation growth) and changes induced to soil hydrology, nutrient cycling and microbial activity, principally denitrification. Few studies have focused on species‐dependent effects on N movement through soil and across boundaries. We propose a new framework, based on a literature review of plant traits with respect to N cycling, which can be used to select plant species with traits likely to maximise N removal during transport through the riparian zone. In the proposed framework, inter‐specific differences in traits known to influence N mobility: root form, growth rate, foliar characteristics and rhizosphere processes, are used to describe species’ potential impact on N removal. Plant trait data may be drawn from studies outside the riparian zone; for example forest ecology, horticulture or forestry research, and candidate species are scored to predict N removal efficiency. We apply the framework to New Zealand's native riparian plant assemblages to demonstrate the trait‐based approach. This framework can guide restoration management decisions and investment in riparian revegetation in a manner that is not restricted to geographically specific or well‐studied species.

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Section: Discussionmentioning

confidence: 97%

Plants for nitrogen management in riparian zones: A proposed trait‐based framework to select effective species

Franklin¹,

Robinson²,

Dickinson³

2019

Eco Management Restoration

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“…Seeps are of great import to the headwater hydrologic system as they collectively can supply between 50 and 80% of stream baseflow (Morley et al ). In headwaters with groundwater nitrogen legacies, a problem common to parts of the Appalachian region (Gurdak and Qi ), riparian seeps with hydrologic connections to these nitrogen‐rich aquifers can exert strong controls on stream water nitrate‐N concentrations in forested (Burns et al ; West et al ; O'Driscoll and DeWalle ; Kaur et al ) and agricultural (Williams et al , ) basins alike. Hence, delineating hydrologic and pedogenic factors influencing groundwater flow and discharge to riparian seeps is critical to their successful management and protection, as well as the headwater streams to which they drain.…”

Section: Introductionmentioning

confidence: 99%

“…In this case study, we applied time‐lapse ERI over the course of several spring rainfall events to investigate the development and hydrologic activation of seeps in the riparian area of a headwater agricultural watershed where seeps collectively represent important sources of water and nutrients to the stream (Williams et al ; ). We selected two distinct sites for monitoring in the riparian zone, including a seep area with evident groundwater discharge and an adjacent area lacking such seepage.…”

Section: Introductionmentioning

confidence: 99%

Imaging Hydrological Processes in Headwater Riparian Seeps with Time‐Lapse Electrical Resistivity

Williams¹,

Buda

Singha

et al. 2016

Groundwater

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Delineating hydrologic and pedogenic factors influencing groundwater flow in riparian zones is central in understanding pathways of water and nutrient transport. In this study, we combined two-dimensional time-lapse electrical resistivity imaging (ERI) (depth of investigation approximately 2 m) with hydrometric monitoring to examine hydrological processes in the riparian area of FD-36, a small (0.4 km ) agricultural headwater basin in the Valley and Ridge region of east-central Pennsylvania. We selected two contrasting study sites, including a seep with groundwater discharge and an adjacent area lacking such seepage. Both sites were underlain by a fragipan at 0.6 m. We then monitored changes in electrical resistivity, shallow groundwater, and nitrate-N concentrations as a series of storms transitioned the landscape from dry to wet conditions. Time-lapse ERI revealed different resistivity patterns between seep and non-seep areas during the study period. Notably, the seep displayed strong resistivity reductions (∼60%) along a vertically aligned region of the soil profile, which coincided with strong upward hydraulic gradients recorded in a grid of nested piezometers (0.2- and 0.6-m depth). These patterns suggested a hydraulic connection between the seep and the nitrate-rich shallow groundwater system below the fragipan, which enabled groundwater and associated nitrate-N to discharge through the fragipan to the surface. In contrast, time-lapse ERI indicated no such connections in the non-seep area, with infiltrated rainwater presumably perched above the fragipan. Results highlight the value of pairing time-lapse ERI with hydrometric and water quality monitoring to illuminate possible groundwater and nutrient flow pathways to seeps in headwater riparian areas.

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“…The efficiency of riparian zones in modifying solute loads depends on the hydrologic connection between biogeochemically distinct patches (Dent et al 2001), discharge through the riparian zone (Hill 1991, Williams et al 2014, and hydrologic residence time within riparian flow paths (Burt 2005). The riparian subsurface is colonized by metabolically diverse microorganisms (Baker et al 2000, Dent et al 2001, Battin et al 2008 and is characterized by variable pools of potentially limiting nutrients, which creates a patchy environment.…”

mentioning

confidence: 99%

Hydrologic and biogeochemical influences on carbon processing in the riparian zone of a subarctic stream

2015

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Small streams and their adjacent riparian zones contribute disproportionately to the processing and transport of C compared to the catchment area and, thereby, may alter the flux of dissolved organic C (DOC) from aquatic ecosystems. We examined the factors influencing C uptake and CO 2 production in the riparian zone of a boreal stream. We tested the hypothesis that enhanced water velocity increases the supply of DOC and nutrients to microorganisms and, therefore, enhances DOC mineralization in the riparian zone. We measured in situ DOC mineralization rate in the riparian zone of a headwater stream at locations that varied with respect to the water velocity of shallow ground water. We added acetate as a tracer to measure C uptake in shallow ground water and monitored CO 2 production during tracer experiments. We assessed relationships of these measures of C dynamics with the time that the tracer remained in shallow ground water surrounding the injection site (plume residence time), pre-injection DOC concentration, nutrient availability, and aromaticity of dissolved organic matter. Acetate uptake rate varied 2 orders of magnitude from −0.002 to −0.19/min, whereas CO 2 production rate varied 5-fold from 0.01 to 0.06/min. Acetate uptake rate was negatively correlated with mean plume residence time, indicating that rapid water velocity increased C decomposition in the riparian zone. Moreover, Damköhler numbers (Da) were generally <1, indicating that substrate uptake was slower than hydrologic transport. Neither acetate nor CO 2 rates were correlated with pre-injection riparian groundwater chemistry. Spatial heterogeneity of water velocity in the subsurface has a critical influence on the processing and subsequent export of C and nutrients from the riparian zone to streams.

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Groundwater flow path dynamics and nitrogen transport potential in the riparian zone of an agricultural headwater catchment

Cited by 47 publications

References 43 publications

Plants for nitrogen management in riparian zones: A proposed trait‐based framework to select effective species

Plants for nitrogen management in riparian zones: A proposed trait‐based framework to select effective species

Imaging Hydrological Processes in Headwater Riparian Seeps with Time‐Lapse Electrical Resistivity

Hydrologic and biogeochemical influences on carbon processing in the riparian zone of a subarctic stream

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