Hydrological connectivity in the aquifer–river continuum: Impact of river stages on the geochemistry of groundwater floodplains

Biehler, Antoine; Chaillou, Gwénaëlle; Buffin‐Bélanger, Thomas; Baudron, Paul

doi:10.1016/j.jhydrol.2020.125379

Cited by 22 publications

(7 citation statements)

References 54 publications

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“…Being able to continuously monitor the temporal dynamic of exchanges is a very promising achievement that could be useful for understanding the hydrological behaviour in the watershed but also for characterizing the distribution of response times of groundwater discharge. This can be particularly useful for studying biogeochemical hotspots and hot moments (Krause et al, 2017;Singh et al, 2019;Trauth and Fleckenstein, 2017) or to couple this approach with natural tracers to assess the residence times in the hyporheic zone (Biehler et al, 2020;Liao et al, 2021).…”

Section: Discussionmentioning

confidence: 99%

Combining passive and active distributed temperature sensing measurements to locate and quantify groundwater discharge variability into a headwater stream

Simon

Bour

Faucheux

et al. 2022

Hydrol. Earth Syst. Sci.

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Abstract. Exchanges between groundwater and surface water play a key role for ecosystem preservation, especially in headwater catchments where groundwater discharge into streams highly contributes to streamflow generation and maintenance. Despite several decades of research, investigating the spatial variability in groundwater discharge into streams still remains challenging mainly because groundwater/surface water interactions are controlled by multi-scale processes. In this context, we evaluated the potential of using FO-DTS (fibre optic distributed temperature sensing) technology to locate and quantify groundwater discharge at a high resolution. To do so, we propose to combine, for the first time, long-term passive DTS measurements and active DTS measurements by deploying FO cables in the streambed sediments of a first- and second-order stream in gaining conditions. The passive DTS experiment provided 8 months of monitoring of streambed temperature fluctuations along more than 530 m of cable, while the active DTS experiment, performed during a few days, allowed a detailed and accurate investigation of groundwater discharge variability over a 60 m length heated section. Long-term passive DTS measurements turn out to be an efficient method to detect and locate groundwater discharge along several hundreds of metres. The continuous 8 months of monitoring allowed the highlighting of changes in the groundwater discharge dynamic in response to the hydrological dynamic of the headwater catchment. However, the quantification of fluxes with this approach remains limited given the high uncertainties on estimates, due to uncertainties on thermal properties and boundary conditions. On the contrary, active DTS measurements, which have seldom been performed in streambed sediments and never applied to quantify water fluxes, allow for the estimation of the spatial distribution of both thermal conductivities and the groundwater fluxes at high resolution all along the 60 m heated section of the FO cable. The method allows for the description of the variability in streambed properties at an unprecedented scale and reveals the variability in groundwater inflows at small scales. In the end, this study shows the potential and the interest of the complementary use of passive and active DTS experiments to quantify groundwater discharge at different spatial and temporal scales. Thus, results show that groundwater discharges are mainly concentrated in the upstream part of the watershed, where steepest slopes are observed, confirming the importance of the topography in the stream generation in headwater catchments. However, through the high spatial resolution of measurements, it was also possible to highlight the presence of local and highly contributive groundwater inflows, probably driven by local heterogeneities. The possibility to quantify groundwater discharge at a high spatial resolution through active DTS offers promising perspectives for the characterization of distributed responses times but also for studying biogeochemical hotspots and hot moments.

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Section: Discussionmentioning

confidence: 99%

Combining passive and active distributed temperature sensing measurements to locate and quantify groundwater discharge variability into a headwater stream

Simon

Bour

Faucheux

et al. 2022

Hydrol. Earth Syst. Sci.

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“…Nevertheless, it is worth noting that subsurface pressure transfers operating between the straightened stream and the stream limit of the floodplain, and between the hillslopes and the lateral limit of the floodplain, remain active at least for part of the year, which contrasts with findings by Lewandowski et al (2009) in an abandoned meander of the lowland River Spree (Germany). This connectivity varies in time and space depending on the texture and configuration of the floodplain and hillslope material, the orientation and magnitude of the hydraulic gradients, and the antecedent saturation conditions, as observed in natural meandering lowland streams (Biehler, Chaillou, Buffin‐Bélanger, & Baudron, 2020; Boulton, Findlay, Marmonier, Stanley, & Valett, 1998; Cranswick & Cook, 2015).…”

Section: Discussionmentioning

confidence: 99%

High‐resolution spatiotemporal analysis of hydrologic connectivity in the historical floodplain of straightened lowland agricultural streams

Marchand

Biron

Buffin‐Bélanger

et al. 2022

River Research & Apps

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In agricultural watersheds, human interventions such as channel straightening have disrupted the hydrologic connectivity between headwater streams and their riparian environment and have thus undermined the ecological services provided by these small streams. Knowledge of the hydrologic connectivity between these streams and their immediate environment (shallow riparian groundwater in the historical floodplain and on adjacent hillslopes) in human-impacted settings is critical for understanding and restoring these hydrological systems but remains largely incomplete. The objective of this research is to investigate the hydrogeomorphological conditions controlling hydrologic connectivity in the historical floodplain of straightened lowland streams. Detailed measurements on the spatiotemporal variability of groundwatersurface water interactions between straightened reaches, historical floodplain including abandoned meanders, and the adjacent hillslopes were obtained using a dense network of piezometers at two sites in the St. Lawrence Lowlands (Quebec, Canada).Results show that the complex mechanisms controlling hydrologic connectivity in naturally meandering lowland rivers also operate in highly disturbed straightened reaches, despite backfilling and agricultural practices. The pre-straightening hydrogeomorphological configuration of the floodplain partly explains the complex patterns of piezometric fluctuations observed at the sites. The apex of the abandoned meanders stands out as a focal area of hydrologic connectivity as water levels indicate pressure transfer that may reflect flows from the stream, the hillslopes, and the surrounding historical floodplain. These unique field observations suggest that abandoned meanders should be promoted as key elements of restoration strategies in lowland agricultural straightened headwater streams.

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“…Geostatistical methods have also been used to identify and understand the distribution of different water sources within riparian zones (Lessels et al, 2016). However, these approaches rely on intense water sampling for identifying the extent to which different water sources mix (Biehler et al, 2020;Lessels et al, 2016;Schneider et al, 2011). Yet, such methods still have limitations in capturing the full spatiotemporal dynamics of SW-GW exchange and mixing in stream corridors.…”

Section: Importance Of Mixing At the Riparian Zonementioning

confidence: 99%

Spatiotemporal variations in water sources and mixing spots in a riparian zone

Nogueira

Schmidt

Partington

et al. 2022

Hydrol. Earth Syst. Sci.

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Abstract. Riparian zones are known to modulate water quality in stream corridors. They can act as buffers for groundwater-borne solutes before they enter the stream at harmful, high concentrations or facilitate solute turnover and attenuation in zones where stream water (SW) and groundwater (GW) mix. This natural attenuation capacity is strongly controlled by the dynamic exchange of water and solutes between the stream and the adjoining aquifer, creating potential for mixing-dependent reactions to take place. Here, we couple a previously calibrated transient and fully integrated 3D surface–subsurface numerical flow model with a hydraulic mixing cell (HMC) method to map the source composition of water along a net losing reach (900 m) of the fourth-order Selke stream and track its spatiotemporal evolution. This allows us to define zones in the aquifer with more balanced fractions of the different water sources per aquifer volume (called mixing hot spots), which have a high potential to facilitate mixing-dependent reactions and, in turn, enhance solute turnover. We further evaluated the HMC results against hydrochemical monitoring data. Our results show that, on average, about 50 % of the water in the alluvial aquifer consists of infiltrating SW. Within about 200 m around the stream, the aquifer is almost entirely made up of infiltrated SW with practically no significant amounts of other water sources mixed in. On average, about 9 % of the model domain could be characterized as mixing hot spots, which were mainly located at the fringe of the geochemical hyporheic zone rather than below or in the immediate vicinity of the streambed. This percentage could rise to values nearly 1.5 times higher following large discharge events. Moreover, event intensity (magnitude of peak flow) was found to be more important for the increase in mixing than event duration. Our modeling results further suggest that discharge events more significantly increase mixing potential at greater distances from the stream. In contrast near and below the stream, the rapid increase in SW influx shifts the ratio between the water fractions to SW, reducing the potential for mixing and the associated reactions. With this easy-to-transfer framework, we seek to show the applicability of the HMC method as a complementary approach for the identification of mixing hot spots in stream corridors, while showing the spatiotemporal controls of the SW–GW mixing process and the implications for riparian biogeochemistry and mixing-dependent turnover processes.

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Hydrological connectivity in the aquifer–river continuum: Impact of river stages on the geochemistry of groundwater floodplains

Cited by 22 publications

References 54 publications

Combining passive and active distributed temperature sensing measurements to locate and quantify groundwater discharge variability into a headwater stream

Combining passive and active distributed temperature sensing measurements to locate and quantify groundwater discharge variability into a headwater stream

High‐resolution spatiotemporal analysis of hydrologic connectivity in the historical floodplain of straightened lowland agricultural streams

Spatiotemporal variations in water sources and mixing spots in a riparian zone

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