Transient analysis of fluctuations of electrical conductivity as tracer in the stream bed

Schmidt, Christian; Musolff, Andreas; Trauth, Nico; Vieweg, Michael; Fleckenstein, Jan H.

doi:10.5194/hess-16-3689-2012

Cited by 33 publications

(38 citation statements)

References 35 publications

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“…[], and Schmidt et al . [] also interpreted decreases in fluid EC in hyporheic pore waters during high surface flows as an increasing surface water influence, and subsequent increased fluid EC during low flows as a decreasing surface water influence and increasing groundwater contributions. Unlike Malcolm et al .…”

Section: Discussionmentioning

confidence: 98%

Temporal responses of groundwater‐surface water exchange to successive storm events

Dudley-Southern

Binley

2015

Water Resources Research

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Groundwater-surface water exchange within the hyporheic zone is widely recognized as a key mechanism controlling the fate of nutrients within catchments. In gaining river systems, groundwatersurface water interactions are constrained by upwelling groundwater but there is increasing evidence that a rapid rise in river stage during storm events can result in a temporary reversal of vertical hydraulic gradients, leading to surface water infiltration into the subsurface and supply of surface-borne reactive solutes to this biogeochemically active interface. At a UK study site, using logged hydraulic heads in the surface water, riverbed, and riverbanks and logged electrical conductivity at multiple depths in the riverbed we show that storm events can lead to a temporary reversal of vertical hydraulic gradient with mixing evident up to 30 cm beneath the riverbed. Cross-channel variability is evident, with the center of the channel consistently having shorter reversals of hydraulic gradient, compared to the channel margins. The direction of shallow subsurface riverbank flow at the site is also reactive to storm events, temporarily aligning with the surface flow direction and then reverting back to preevent conditions. Such a transition of flow paths during events is also likely to lead to expansion of lateral hyporheic exchange. This study provides evidence that storm events can be a key driver of enhanced hyporheic exchange in gaining river systems, which may support nutrient reactions beyond the duration of event-driven change. Our observations demonstrate the dynamic nature of the hyporheic zone, which should be considered when evaluating its biogeochemical function.

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Section: Discussionmentioning

confidence: 98%

Temporal responses of groundwater‐surface water exchange to successive storm events

Dudley-Southern

Binley

2015

Water Resources Research

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“…These models generally simplify the complex flowpaths and boundary conditions of natural systems (Suckow 2014). There has been a large effort to increase the mathematical rigor of the models that use temperature and EC as τ tracers in TSZs (Cirpka et al 2007;Vogt et al 2010Vogt et al , 2012Rau et al 2012;Schmidt et al 2012;Vieweg et al 2016), especially related to uncertainty analysis and dynamic boundary conditions (Rau et al 2015;Vandersteen et al 2015). This effort is due in part to the low cost of temperature sensors, but also to the complexity of the heat transport equation when used for hyporheic sediments with variable boundary conditions (one-to three-dimensional (1-3D) flow, variable upper boundary, variably saturated flow (Cuthbert and Mackay 2013;Rau et al 2017).…”

Section: Introductionmentioning

confidence: 99%

Explicit Modeling of Radon‐222 in HydroGeoSphere During Steady State and Dynamic Transient Storage

et al. 2018

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Transient storage zones (TSZs) are located at the interface of rivers and their abutting aquifers and play an important role in hydrological and biogeochemical functioning of rivers. The natural radioactive tracer 222Rn is a particularly well‐suited tracer for studying TSZ water exchange and age. Although 222Rn measurement techniques have developed rapidly, there has been less progress in modeling 222Rn activities. Here, we combine field measurements with the numerical model HydroGeoSphere (HGS) to simulate 222Rn emanation, decay and transport during steady state (riffle‐pool sequence) and transient (bank storage) conditions. Comparing the HGS mean water ages with the conventional 222Rn apparent ages during steady state showed a systemic underestimation of apparent age with increasing dispersion and especially where large concentration gradients exist within the subsurface. A large underestimation of apparent water age was also observed at the advective front during bank storage where regional high 222Rn groundwater mixes with newly infiltrated surface water. The explicit modeling of radiogenic tracers such as 222Rn offers a physical interpretation of this data as well as a useful way to test simplified apparent age models.

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“…They attributed these EC fluctuations to a combination of biological (photosynthesis), chemical (carbonate equilibrium and precipitation), and physical (groundwater exchange) processes. Elsewhere, diel EC variations have been observed in small streams and attributed to evaporative enrichment during daytime (Calles, 1982), or the result of groundwater discharge, since groundwater typically has higher EC values (Schmidt et al, 2012). However, potential explanations for diel cycles in the SPR will need to be studied further over longer time periods that cover seasonal and inter-annual hydroclimatic variability, in combination with additional data, before this aspect can be satisfactorily resolved.…”

Section: Diel Cyclesmentioning

confidence: 99%

High-frequency monitoring of stream water physicochemistry on sub-Antarctic Marion Island

Stowe

Hedding

Eckardt

et al. 2018

WSA

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Given the remoteness and challenging environmental conditions on sub-Antarctic Marion Island, continuous high-resolution studies of the island's natural water systems are rare. Subsequently, current understanding of the island's hydrochemistry is based entirely on manual point-based measurements. To address this research gap we analysed continuous, in-situ highfrequency physicochemical measurements (pH, water temperature, dissolved oxygen (DO), and electrical conductivity (EC)) from the Soft Plume River over the period 21 April 2015-26 April 2015. We observed a sharp, short-term response from all measurements to a precipitation event that was superimposed on consistent but subtle diel (i.e. 24 h) cycles throughout the study. Total variation in pH and electrical conductivity amounted to 1.3 units and 27.7 µS/cm respectively. Stream water temperature was less variable (6.2°C) than air surface temperature (14.2°C). Total variation in DO was 2.0 mg/L. Aside from the precipitation-induced response, diel oscillations were small and only visible through the use of continuous, highresolution monitoring. Findings highlight the advantages of continuous high-frequency monitoring in capturing the range of daily variation and elucidating diel cycles in stream water physicochemistry on sub-Antarctic Marion Island that have not previously been accounted for.

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Transient analysis of fluctuations of electrical conductivity as tracer in the stream bed

Cited by 33 publications

References 35 publications

Temporal responses of groundwater‐surface water exchange to successive storm events

Temporal responses of groundwater‐surface water exchange to successive storm events

Explicit Modeling of Radon‐222 in HydroGeoSphere During Steady State and Dynamic Transient Storage

High-frequency monitoring of stream water physicochemistry on sub-Antarctic Marion Island

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