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Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/hess-2017-374
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
03 Jul 2017
Review status
This discussion paper is a preprint. It has been under review for the journal Hydrology and Earth System Sciences (HESS). The manuscript was not accepted for further review after discussion.
Multi-level qualification of Parafluvial Exchange within the Hyporheic Zone Affected by River Sinuosity and Seasonal Change using Multi-tracer Methods
Amin reza Meghdadi1 and Morteza Eyvazi2 1School of Earth, Environmental and Biological Science, Queensland University of Technology, Brisbane, Qld 4000, Australia
2Department of Agriculture and Plant Breeding, Faculty of Agriculture, Zanjan University, Zanjan, Iran
Abstract. Exchange of water in the parafluvial zone, located along the boundaries of meandering streams, arises in response to seasonal variation and spatial distribution. Remarkably, few studies have applied multi-tracer methods for qualitative scrutiny of losing (recharge) or gaining (discharge) reaches along the parafluvial zone. Hence, the main objective of this study is to qualitatively characterize the spatio-temporal alteration in parafluvial exchange within the hyporheic zone (PEHZ) by simultaneous application of multi-tracer methods. For this approach, first, Hierarchical Cluster Analysis (HCA) in conjunction with groundwater hydrochemistry analysis was used to evaluate the representativeness of parafluvial assessment network. Then, water stable isotope compositions (δ18O and δ2H), radioisotope (222Rn), and environmental tracers (Temperature and EC) were measured at multiple depths (20 cm to 100 cm depths below streambed) during the wet and dry season to qualitatively elucidate the PEHZ in the Ghezel-Ozan River, a third order river located in the northwest of Iran. By groundwater hydrochemistry assessment identified, NaHCO3 and CaHCO3 as the dominant water type in dry and wet season, respectively. Moreover, the HCA approach designed two different clusters for each season for accurate interpretation of PEHZ. Results obtained from stable isotope and environmental tracer analysis of bore water, surface water, and parafluvial water distinguished stream-aquifer connectivity with highly seasonal and spatial variations. In the dry season, for example, δ18O, δ2H, and EC varied from −3.59 to −1.88 (‰ VSMOW), −31.08 to −24.06 (‰ VSMOW), and 234 to 740.65  μS/cm respectively. Also, the results acquired from the integration of δ18O and EC revealed complex spatio-temporal stream-aquifer connectivity (PEHZ). In low flow conditions, groundwater outflow mainly occurred at 100 cm depth while the dominance of groundwater outflow at 20 cm depth prevailed during high flow conditions. The continuous and point scale measurements of temperature and 222Rn were highly in accordance with the results of δ18O and EC. Furthermore, diel temperature fluctuation, as well as radon activity variations at multi-level scale, expressed the PEHZ (especially at depth greater than 60 cm) are affected by large-scale regional flow-field which is embedded within. The synthesized approaches used in this study provide a useful insight into the spatiotemporal changes of stream-aquifer connectivity which make the more efficient monitoring and interpretation of hydrological processes possible. They can be, furthermore, utilized to pinpoint the losing/gaining reaches accurately to tackle environmental problems such as monitoring the transport of anthropogenic contaminants in a system.

Citation: Meghdadi, A. R. and Eyvazi, M.: Multi-level qualification of Parafluvial Exchange within the Hyporheic Zone Affected by River Sinuosity and Seasonal Change using Multi-tracer Methods, Hydrol. Earth Syst. Sci. Discuss., https://doi.org/10.5194/hess-2017-374, 2017.
Amin reza Meghdadi and Morteza Eyvazi
Amin reza Meghdadi and Morteza Eyvazi

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Short summary
parafluvial inflow and outflow have high seasonal variations within the hyporheic zone. As, multi-level integration of EC and δ18O provides a valid mean to assess stream-aquifer connectivity. Daily temperature oscillation and radon activity variation were used to verify the accuracy of results obtained by combination of water isotope and hydrochemistry analysis, as well as it can be indicated that the Parafluvial flow is affected by larger scale flow-field which is embedded within.
parafluvial inflow and outflow have high seasonal variations within the hyporheic zone. As,...
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