Multi-level qualification of Parafluvial Exchange within the Hyporheic Zone Affected by River Sinuosity and Seasonal Change using Multi-tracer Methods

Meghdadi, Amin Reza; Eyvazi, Morteza

doi:10.5194/hess-2017-374

Cited by 3 publications

(3 citation statements)

References 2 publications

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“…Igneous bedrock is the dominant geochemical unit underlying the river sediments. Furthermore, the geology of the study watershed is mainly late Tertiary to early Quaternary calcareous sands, basalt, and clay (Meghdadi and Eyvazi, 2017). Four zones located in the thalweg path of the sinuously flowing stream and characterised by different morphological and hydrodynamic features (multiple riffle-pool sequences, Figure 1A) were 15 chosen to fulfil the study requirements.…”

Section: Study Areamentioning

confidence: 99%

“…In total there were 33 testing points and 11 cross sections arranged perpendicularly or parallel to the stream flow direction ( Figure 1B). A set of 33 multi-level sampler (MLS) piezometers (Meghdadi and Eyvazi, 2017) was constructed using galvanized steel pipe with inside diameter (ID) of 70 mm https://doi.org/10.5194/hess-2019-446 Preprint. Discussion started: 2 October 2019 c Author(s) 2019.…”

Section: Sampling and Field Data Measurementsmentioning

confidence: 99%

“…Hyporheic exchange is mainly governed by riverbed morphological features such as riffle-pool sequences (Gariglio et al, 2013), stream sinuosity and curvature (Meghdadi and Eyvazi, 2017;Zhang et al, 2017), and stream sedimentary properties (Song et al, 2017). These complex and 5 varied stream morphological features increase the difficulties in understanding the magnitude of the hyporheic exchange.…”

Section: Introductionmentioning

confidence: 99%

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Quantifying Vertical Hyporheic Exchange and hyporheic residence time in thalweg paths of meandering streams characterized by multiple riffle-pool sequences morphology

Meghdadi¹,

Eyvazi

Najatijahromi

et al. 2019

Preprint

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Abstract. Riffle-pool sequences in the thalweg paths of meandering streams are of pivotal importance to the hyporheic exchange pattern in a fluvial network, but the complex hydrodynamic, morphological, and sedimentary features of riverbed sediments increase the difficulties associated with vertical hyporheic exchange (VHE) quantification. This study applied depth-dependent radon (222Rn) and diel temperature variations to quantify VHE and residence time (tr). The study was conducted in four different hyporheic areas with riffle-pool sequences in the third-order Ghezel-Ozan River, located in north-west Iran. The mean values of temperature-derived VHE (VHET) and radon-derived VHE (VHERn) were 0.67±0.32 m/day and 0.63±0.36 m/day, respectively. Due to effects of sediment bed heterogeneity on temperature variation and 222Rn activity at downwelling and upwelling points, there were discrepancies between radon-derived (trRn) and temperature-derived residence time (trT), with mean values of 2.11±1.17 days and 1.87±1.26 days, respectively. The value of trT was well within uncertainty boundaries at a 95 percent confidence interval (p<0.05) and was lower than trRn at the downwelling points. The analysis of vertical diel temperature, radon and electrical conductivity variations revealed subsurface water exchange to be greatly affected by larger scale regional flow. The comparison between VHET and VHERn with VHE obtained from PHAST model simulation (VHEPHAST) revealed a higher correlation between VHET and VHEPHAST (R2=0.96) than with VHERn (R2=0.76). Furthermore, vertical hydraulic conductivity (Kv) of the sediment-bed materials, calculated in situ by the permeameter test, indicated not only that Kv was up to 21 % higher in areas dominated by upward movement than at downwelling points, but also principle component analysis (PCA) demonstrated the dependence of Kv on porosity, VHE, and %sand of the stream-bed materials. This study provides evidence that vertical flux in the hyporheic zone is mainly affected by stream sinuosity and regional subsurface flow, and that the temperature method is more suitable than radon activity to quantify hyporheic exchange patterns.

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Section: Study Areamentioning

confidence: 99%

Section: Sampling and Field Data Measurementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Quantifying Vertical Hyporheic Exchange and hyporheic residence time in thalweg paths of meandering streams characterized by multiple riffle-pool sequences morphology

Meghdadi¹,

Eyvazi

Najatijahromi

et al. 2019

Preprint

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Ecological water health assessment using benthic macroinvertebrate communities (case study: the Ghezel Ozan River in Zanjan Province, Iran)

Aazami

KianiMehr

Zamani

2019

Environ Monit Assess

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Characterizing the capacity of hyporheic sediments to attenuate groundwater nitrate loads by adsorption

Meghdadi

2018

Water Research

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Nitrate has been recognized as a global threat to environmental health. In this regard, the hyporheic zone (saturated media beneath and adjacent to the stream bed) plays a crucial role in attenuating groundwater nitrate, prior to discharge into surface water. While different nitrate removal pathways have been investigated over recent decades, the adsorption capacity of hyporheic sediments under natural conditions has not yet been identified. In this study, the natural attenuation capacity of the hyporheic-sediments of the Ghezel-Ozan River, located in the north-west of Iran, was determined. The sampled sediments (from 1 m below the stream bed) were characterized via XRD, FT-IR, BET, SEM, BJH, and Zeta potential. Nitrate adsorption was evaluated using a batch experiment with hyporheic pore-water from each study site. The study was performed in the hyporheic sediments of two morphologically different zones, including Z located in the parafluvial zone having the clay sediment texture (57.8% clay) with smectite/Illite mixed layer clay type and Z located in the river confluence area containing silty clay sediment texture (47.6% clay) with smectite/kaolinite mixed layer clay type. Data obtained from the batch experiment were subjected to pseudo-first order, pseudo-second order, intra-particle diffusion, and Elovich mass transfer kinetic models to characterize the nitrate adsorption mechanism. Furthermore, to replicate nitrate removal efficiencies of the hyporheic sediments under natural conditions, the sampled hyporheic pore-waters were applied as initial solutions to run the batch experiment. The results of the artificial nitrate solution correlated well with pseudo-second order (R>95%; in both Z and Z) and maximum removal efficiencies of 85.3% and 71.2% (adsorbent dosage 90 g/L, pH = 5.5, initial adsorbate concentration of 90 mg/L) were achieved in Z and Z, respectively. The results of the nitrate adsorption analysis revealed that the nitrate removal efficiencies varied from 17.24 ± 1.86% in Z during the wet season to 28.13 ± 0.89% in Z during the dry season. The results obtained by this study yielded strong evidence of the potential of hyporheic sediments to remove nitrate from an aqueous environment with great efficiency.

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Multi-level qualification of Parafluvial Exchange within the Hyporheic Zone Affected by River Sinuosity and Seasonal Change using Multi-tracer Methods

Cited by 3 publications

References 2 publications

Quantifying Vertical Hyporheic Exchange and hyporheic residence time in thalweg paths of meandering streams characterized by multiple riffle-pool sequences morphology

Quantifying Vertical Hyporheic Exchange and hyporheic residence time in thalweg paths of meandering streams characterized by multiple riffle-pool sequences morphology

Ecological water health assessment using benthic macroinvertebrate communities (case study: the Ghezel Ozan River in Zanjan Province, Iran)

Characterizing the capacity of hyporheic sediments to attenuate groundwater nitrate loads by adsorption

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