Transient hyporheic exchange during rainfall events in a gaining stream: Field investigation, conceptual model, and numerical interpretation

2020 ◽  
Author(s):  
Chengpeng Lu ◽  
Keyan Ji ◽  
Yong Zhang ◽  
Jan Fleckenstein ◽  
Chunmiao Zheng ◽  
...  
Keyword(s):  
Numerical Modeling ◽  
Conceptual Model ◽  
Hyporheic Zone ◽  
Flow Model ◽  
Surface Flow ◽  
Hyporheic Exchange ◽  
Biogeochemical Processes ◽  
Cross Sectional ◽  
Rainfall Events ◽  
Hyporheic Flow

<p>Hyporheic exchange is transient in nature, considering the temporal fluctuations in hydrological and/or biogeochemical conditions in surface water and groundwater (SW/GW).  Efforts are needed to further identify the patterns and driving mechanisms of transient hyporheic exchange.  This study combined a reach-scale field survey and numerical modeling analysis to reveal the pattern of transient hyporheic exchange during rainfall events in the Zhongtian River, southeast of China. Field observations revealed hydrodynamic properties and temperature variations in SW/GW, suggesting that the regional groundwater recharged the study reach.  A one-dimensional heat transport solution was built and used to generate the planar and cross-sectional hyporheic flow fields. A two-step numerical modeling procedure, including a hydraulic surface flow model and a groundwater flow model, was then used to simulate the observed flow system. The hyporheic exchange exhibited strong temporal evolution, as indicated by the rainfall event-driven hyporheic exchange, the depth-dependent hysteretic response to rainfall, and the area of local downwelling flow increasing with rainfall. Dynamics of the hyporheic exchange in the study reach, therefore, significantly changed in space and time due to rainfall. The reversal of hydraulic gradient and transient hyporheic exchange were observed and validated using the numerical simulation. Anisotropic hydraulic conductivity is the key to generate transient hyporheic exchange. A revised conceptual model was used to interpret the observed temporal patterns in hyporheic exchange  The pattern of transient hyporheic exchange indicates that transient hyporheic exchange only appears after an increased phase of river stage but does not last for a long time. The temporal pattern of hyporheic exchange can significantly affect the evolution of biogeochemical processes in the hyporheic zone for a gaining stream by, for example, temporally facilitating special biogeochemical processes.</p>

scholarly journals Occurence of microplastics in the hyporheic zone of rivers

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
S. Frei ◽  
S. Piehl ◽  
B. S. Gilfedder ◽  
M. G. J. Löder ◽  
J. Krutzke ◽  
...  
Keyword(s):  
Drinking Water ◽  
Food Webs ◽  
Hyporheic Zone ◽  
River Sediments ◽  
Size Fraction ◽  
Dry Weight ◽  
Surface Flow ◽  
Hyporheic Exchange ◽  
Pore Scale ◽  
River Bank

Abstract Although recent studies indicate that fluvial systems can be accumulation areas for microplastics (MPs), the common perception still treats rivers and streams primarily as pure transport vectors for MPs. In this study we investigate the occurrence of MPs in a yet unnoticed but essential compartment of fluvial ecosystems - the hyporheic zone (HZ). Larger MP particles (500–5,000 µm) were detected using attenuated total reflectance (ATR) - Fourier-transform infrared (FTIR) spectroscopy. Our analysis of MPs (500–5,000 µm) in five freeze cores extracted for the Roter Main River sediments (Germany) showed that MPs were detectable down to a depth of 0.6 m below the streambed in low abundances (≪1 particle per kg dry weight). Additionally, one core was analyzed as an example for smaller MPs (20–500 µm) with focal plane array (FPA)- based µFTIR spectroscopy. Highest MP abundances (~30,000 particles per kg dry weight) were measured for pore scale particles (20–50 µm). The detected high abundances indicate that the HZ can be a significant accumulation area for pore scale MPs (20–50 µm), a size fraction that yet is not considered in literature. As the HZ is known as an important habitat for invertebrates representing the base of riverine food webs, aquatic food webs can potentially be threatened by the presence of MPs in the HZ. Hyporheic exchange is discussed as a potential mechanism leading to a transfer of pore scale MPs from surface flow into streambed sediments and as a potential vector for small MPs to enter the local aquifer. MPs in the HZ therefore may be a potential risk for drinking water supplies, particularly during drinking water production via river bank filtration.

scholarly journals Insight into the influence of local streambed heterogeneity on hyporheic-zone flow characteristics

2020 ◽  
Vol 28 (8) ◽  
pp. 2697-2712
Author(s):  
Robert Earon ◽  
Joakim Riml ◽  
Liwen Wu ◽  
Bo Olofsson
Keyword(s):  
Surface Water ◽  
Hydraulic Conductivity ◽  
Penetration Depth ◽  
Hyporheic Zone ◽  
Flow Characteristics ◽  
Time Lapse ◽  
Hyporheic Exchange ◽  
Tracer Injection ◽  
Hyporheic Flow ◽  
Exchange Processes

AbstractInteraction between surface water and groundwater plays a fundamental role in influencing aquatic chemistry, where hyporheic exchange processes, distribution of flow paths and residence times within the hyporheic zone will influence the transport of mass and energy in the surface-water/groundwater system. Geomorphological conditions greatly influence hyporheic exchange, and heterogeneities such as rocks and clay lenses will be a key factor for delineating the hyporheic zone. Electrical resistivity tomography (ERT) and ground-penetrating radar (GPR) were used to investigate the streambed along a 6.3-m-long reach in order to characterise geological layering and distinct features which may influence parameters such as hydraulic conductivity. Time-lapse ERT measurements taken during a tracer injection demonstrated that geological features at the meter-scale played a determining role for the hyporheic flow field. The penetration depth of the tracer into the streambed sediment displayed a variable spatial pattern in areas where the presence of highly resistive anomalies was detected. In areas with more homogeneous sediments, the penetration depth was much more uniformly distributed than observed in more heterogeneous sections, demonstrating that ERT can play a vital role in identifying critical hydraulic features that may influence hyporheic exchange processes. Reciprocal ERT measurements linked variability and thus uncertainty in the modelled resistivity to the spatial locations, which also demonstrated larger variability in the tracer penetration depth, likely due to local heterogeneity in the hydraulic conductivity field.

scholarly journals Influence of Streambed Heterogeneity on Hyporheic Flow and Sorptive Solute Transport

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1547 ◽  
Author(s):  
Yuanhong Liu ◽  
Corey D. Wallace ◽  
Yaoquan Zhou ◽  
Reza Ershadnia ◽  
Faranak Behzadi ◽  
...  
Keyword(s):  
Solute Transport ◽  
Hyporheic Zone ◽  
Preferential Flow ◽  
Hyporheic Exchange ◽  
Sorptive Capacity ◽  
Hyporheic Flow ◽  
Sedimentary Architecture ◽  
Mixing Dynamics ◽  
Facies Types ◽  
Sediment Heterogeneity

The subsurface region where river water and groundwater actively mix (the hyporheic zone) plays an important role in conservative and reactive solute transport along rivers. Deposits of high-conductivity (K) sediments along rivers can strongly control hyporheic processes by channeling flow along preferential flow paths wherever they intersect the channel boundary. Our goal is to understand how sediment heterogeneity influences conservative and sorptive solute transport within hyporheic zones containing high- and low-K sediment facies types. The sedimentary architecture of high-K facies is modeled using commonly observed characteristics (e.g., volume proportion and mean length), and their spatial connectivity is quantified to evaluate its effect on hyporheic mixing dynamics. Numerical simulations incorporate physical and chemical heterogeneity by representing spatial variability in both K and in the sediment sorption distribution coefficient ( K d ). Sediment heterogeneity significantly enhances hyporheic exchange and skews solute breakthrough behavior, while in homogeneous sediments, interfacial flux and solute transport are instead controlled by geomorphology and local-scale riverbed topographies. The hyporheic zone is compressed in sediments with high sorptive capacity, which limits solute interactions to only a small portion of the sedimentary architecture and thus increases retention. Our results have practical implications for groundwater quality, including remediation strategies for contaminants of emerging concern.

scholarly journals The Effect of Stream Discharge on Hyporheic Exchange

Water ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1436 ◽  
Author(s):  
Brian Babak Mojarrad ◽  
Andrea Betterle ◽  
Tanu Singh ◽  
Carolina Olid ◽  
Anders Wörman
Keyword(s):  
Hyporheic Zone ◽  
Hyporheic Exchange ◽  
Subsurface Water ◽  
Stream Discharge ◽  
Hyporheic Flow ◽  
Sediment Permeability ◽  
Natural Tracer ◽  
Streambed Sediments ◽  
The Impact ◽  
Numerical Approaches

Streambed morphology, streamflow dynamics, and the heterogeneity of streambed sediments critically controls the interaction between surface water and groundwater. The present study investigated the impact of different flow regimes on hyporheic exchange in a boreal stream in northern Sweden using experimental and numerical approaches. Low-, base-, and high-flow discharges were simulated by regulating the streamflow upstream in the study area, and temperature was used as the natural tracer to monitor the impact of the different flow discharges on hyporheic exchange fluxes in stretches of stream featuring gaining and losing conditions. A numerical model was developed using geomorphological and hydrological properties of the stream and was then used to perform a detailed analysis of the subsurface water flow. Additionally, the impact of heterogeneity in sediment permeability on hyporheic exchange fluxes was investigated. Both the experimental and modelling results show that temporally increasing flow resulted in a larger (deeper) extent of the hyporheic zone as well as longer hyporheic flow residence times. However, the result of the numerical analysis is strongly controlled by heterogeneity in sediment permeability. In particular, for homogeneous sediments, the fragmentation of upwelling length substantially varies with streamflow dynamics due to the contribution of deeper fluxes.

Mapping increases in hyporheic exchange from channel-spanning logjams

2020 ◽  
Author(s):  
Kamini Singha ◽  
Megan Doughty ◽  
Sawyer McFadden ◽  
Audrey Hucks Sawyer ◽  
Ellen Wohl
Keyword(s):  
Numerical Modeling ◽  
Hyporheic Zone ◽  
Single Channel ◽  
Tracer Tests ◽  
Field Measurements ◽  
Hyporheic Exchange ◽  
Exchange Flow ◽  
Stream Monitoring ◽  
Solute Retention ◽  
Flow Pathways

<p>Logjams increase hydraulic resistance and create hydraulic head gradients along the streambed that drive groundwater-surface water exchange. Here, we quantify changes in hyporheic exchange flow due to channel-spanning logjams using field measurements and numerical modeling in MODFLOW and MT3DMS. Electrical resistivity (ER) imaging was used to monitor the transport of solutes into the hyporheic zone during a series of in-stream tracer tests supplemented by in-stream monitoring. We conducted experiments in a variety of reaches in Little Beaver Creek, Colorado (USA) of varying complexity: a control reach with no logjams, a reach with a single, channel-spanning logjam, and additional jams with greater logjam complexity. Our results show that 1) higher hyporheic exchange flow occurs at reach with logjams, 2) logjams create complex hyporheic exchange flow pathways that can cause bimodal solute breakthrough behavior downstream, and 3) higher discharge rates associated with spring snowmelt increase the extent and magnitude of hyporheic exchange flow. The numerical modeling supports all three field findings, and also suggest that lower flows increase solute retention in streams, although this last conclusion is not strongly supported by field results. This study represents the first use of ER to explore hyporheic exchange flow around a naturally occurring logjam over different stream discharges and has implications for understanding how logjams influence the transport of solutes, the health of stream ecosystems, and stream restoration and conservation efforts.</p>

Impacts of engineering baffles on the hyporheic exchange in a straight channel with floodplain

2020 ◽  
Author(s):  
Peng Huang ◽  
Ting Fong May Chui
Keyword(s):  
Groundwater Flow ◽  
Hyporheic Zone ◽  
Numerical Models ◽  
Surface Flow ◽  
Hyporheic Exchange ◽  
Ecosystem Functions ◽  
Straight Channel ◽  
Coupled Models ◽  
Overlying Water ◽  
Stream Width

<p>The hyporheic zone (HZ) is the region of saturated sediment surrounding a stream which connects surface water and groundwater flow. The overlying water with dissolved matters infiltrates into the HZ, stays there for some time and interacts with groundwater, and exfiltrates out of the HZ, resulting in hyporheic exchanges (HEs). The HEs support physicochemical and biological reactions that are essential to river ecosystem functions. In recent decades, more and more stream restoration projects involve the recovery of HE, however, effective guidance in restoring HE is still missing. Therefore, this study aims to examine the effectiveness of different engineering baffle designs in restoring HZ in a straight channel with floodplain. Both flume and numerical models coupling stream and groundwater flow were built. The flume model was built in a recirculating box to simulate different hydrological conditions (e.g., streamflow and groundwater flow) and baffle designs (e.g., baffle amplitude, interval). Tracer experiments were performed, and results were used to quantify the impacts of baffles designs on the HE fluxes. For the numerical models, the surface flow was simulated by solving Reynold-average Navier-Stokes (RANS) equations in two phases using volume of fluid method (VoF) in Fluent, while the groundwater flow was simulated by solving Richard’s equation in COMSOL. The numerical models were calibrated with experiments, and could output the flux, scale and median residence time (MRT) of the HE. For fixed baffle interval of four times the stream width, the flux and scale of HE peaked at baffle amplitude of around one third of stream width, while the MRT increased with increasing amplitude. For fixed baffle amplitude of one third of the stream width, the flux of HE peaked at baffle interval of around four times the stream width, the scale of HE was positively correlated to interval while the MTR had the lowest value at the interval of around two times the stream width. The results of this study directly benefit the development of practical baffle designs of river restoration.  The coupled models developed are also generally applicable to investigate the efficiency of different stream rehabilitation designs in restoring HZ.</p>

scholarly journals Hyporheic exchange in recirculating flumes under heterogeneous bacterial and morphological conditions

2021 ◽  
Vol 80 (6) ◽  
Author(s):  
Andrea Betterle ◽  
Anna Jaeger ◽  
Malte Posselt ◽  
Claudia Coll ◽  
Jonathan P. Benskin ◽  
...  
Keyword(s):  
Surface Water ◽  
Numerical Model ◽  
Hyporheic Zone ◽  
Transport Processes ◽  
Hyporheic Exchange ◽  
Numerical Representation ◽  
Experimental Conditions ◽  
Riverine Ecosystems ◽  
Hyporheic Flow ◽  
Intrinsic Complexity

AbstractHyporheic exchange (HE) contributes to the biogeochemical turnover of macro- and micro-pollutants in rivers. However, the spatiotemporal complexity and variability of HE hinder understanding of its role in the overall functioning of riverine ecosystems. The present study focuses on investigating the role of bacterial diversity and sediment morphology on HE using a multi-flume experiment. A fully coupled surface–subsurface numerical model was used to highlight complex exchange patterns between surface water and the underlying flow field in the sediments. Under the experimental conditions, the surface water flow induced by bedforms has a prominent effect on both local trajectories and residence time distributions of hyporheic flow paths, whereas mean hyporheic retention times are mainly modulated by average surface flowrates. In case of complex bedform morphologies, the numerical model successfully reproduces the HE estimated by means of salt dilution tests. However, the 2D numerical representation of the system falls short in predicting HE in absence of bedforms, highlighting the intrinsic complexity of water circulation patterns in real scenarios. Finally, results show that higher bacterial diversities in the stream sediments can significantly reduce hyporheic fluxes. This work provides a framework to interpret micropollutants turnover in light of the underlying physical transport processes in the hyporheic zone. The study emphasizes the importance of better understanding the tradeoff between physically driven transport processes and bacterial dynamics in the hyporheic zone to quantify the fate of pollutants in streams and rivers.

scholarly journals Methane emissions from a sediment-deposited island in a Lancang-Mekong reservoir

2018 ◽  
Author(s):  
Wenqing Shi ◽  
Qiuwen Chen ◽  
Jianyun Zhang ◽  
Cheng Chen ◽  
Yuchen Chen ◽  
...  
Keyword(s):  
Methane Emission ◽  
Hyporheic Zone ◽  
Sediment Accumulation ◽  
Methane Flux ◽  
Methane Emissions ◽  
Mekong River ◽  
Hyporheic Exchange ◽  
Water Level Fluctuations ◽  
Hyporheic Flow ◽  
Methane Sink

Abstract. In dammed rivers, sediment accumulation creates potential methane emission hotspots, which have been extensively studied in forebays. However, methane emissions from sidebays remain poorly understood. We investigated methane emissions from a sediment-deposited island situated in the sidebay of the Manwan Reservoir, Lancang-Mekong River. High methane emissions (maximum 10.4 mg h−1 m−2) were observed at the island center, while a ring-like zone of low-to-negative methane emission was discovered around the island edge, whose flux varied between −0.2–1.6 mg h−1 m−2. The ring-like zone accounted for 89.1 % of the island area, of which 9.1 % was a methane sink zone. Microbial processes in the hyporheic zone, regulated by hydrological variations, were responsible for the low methane flux in this area. Under reservoir operation, frequent water level fluctuations enhanced hyporheic exchange and created redox gradients along the hyporheic flow path. Dissolved oxygen in hyporheic water decreased from 4.80 mg L−1 at the island bank edge to 0.43 mg L−1 at the center, which in turn decreased methanogen abundance for methane production and increased methanotroph abundance for methane oxidation at the ring-like zone. This study adds to our understanding of methane emissions from dammed rivers and helps to screen efficient strategies for future mitigation of the global warming effects of hydropower systems.

scholarly journals Nitrogen attenuation, dilution and recycling in the intertidal hyporheic zone of a subtropical estuary

2018 ◽  
Vol 22 (7) ◽  
pp. 4083-4096 ◽  
Author(s):  
Sébastien Lamontagne ◽  
Frédéric Cosme ◽  
Andrew Minard ◽  
Andrew Holloway
Keyword(s):  
Surface Water ◽  
Hyporheic Zone ◽  
Isotopic Fractionation ◽  
Hyporheic Exchange ◽  
Biogeochemical Processes ◽  
Intertidal Sediments ◽  
Intertidal Zones ◽  
N Removal ◽  
Subtropical Estuary ◽  
Biogeochemical Transformations

Abstract. Tidal estuarine channels have complex and dynamic interfaces controlled by upland groundwater discharge, waves, tides and channel velocities that also control biogeochemical processes within adjacent sediments. In an Australian subtropical estuary, discharging groundwater with elevated (> 300 mg N L−1) NH4+ and NO3- concentrations had 80 % of the N attenuated at this interface, one of the highest N removal rates (> 100 mmol m−2 day−1) measured for intertidal sediments. The remaining N was also diluted by a factor of 2 or more by mixing with surface water before being discharged to the estuary. Most of the mixing occurred in a hyporheic zone in the upper 50 cm of the channel bed. However, groundwater entering this zone was already partially mixed (12 %–60 %) with surface water via tide-induced circulation. Below the hyporheic zone (50–125 cm below the channel bed), NO3- concentrations declined slightly faster than NH4+ concentrations and δ15NNO3 and δ18ONO3 gradually increased, suggesting a co-occurrence of anammox and denitrification. In the hyporheic zone, δ15NNO3 continued to become enriched (consistent with either denitrification or anammox) but δ18ONO3 became more depleted (indicating some nitrification). A high δ15NNO3 (23 ‰–35 ‰) and a low δ18ONO3 (1.2 ‰–8.2 ‰) in all porewater samples indicated that the original synthetic nitrate pool (industrial NH4NO3; δ15N ∼ 0 ‰; δ18O ∼ 18 ‰–20 ‰) had turned over completely during transport in the aquifer before reaching the channel bed. Whilst porewater NO3- was more δ18O depleted than its synthetic source, porewater δ18OH2O (−3.2 ‰ to −1.8 ‰) was enriched by 1 ‰–4 ‰ relative to rainfall-derived groundwater mixed with seawater. Isotopic fractionation from H2O uptake during the N cycle and H2O production during synthetic NO3- reduction are the probable causes for this δ18OH2O enrichment. Whilst occurring at a smaller spatial scale than tide-induced circulation, hyporheic exchange can provide a similar magnitude of mixing and biogeochemical transformations for groundwater solutes discharging through intertidal zones.

Effects of riffle–step restoration on hyporheic zone chemistry in N-rich lowland streams

2006 ◽  
Vol 63 (1) ◽  
pp. 120-133 ◽  
Author(s):  
Tamao Kasahara ◽  
Alan R Hill
Keyword(s):  
Urban Areas ◽  
Hyporheic Zone ◽  
Stream Water ◽  
Ion Concentration ◽  
Hyporheic Exchange ◽  
Ecosystem Functions ◽  
Exchange Flow ◽  
Nutrient Inputs ◽  
Lowland Streams ◽  
Hyporheic Zones

Stream restoration projects that aim to rehabilitate ecosystem health have not considered surface–subsurface linkages, although stream water and groundwater interaction has an important role in sustaining stream ecosystem functions. The present study examined the effect of constructed riffles and a step on hyporheic exchange flow and chemistry in restored reaches of several N-rich agricultural and urban streams in southern Ontario. Hydrometric data collected from a network of piezometers and conservative tracer releases indicated that the constructed riffles and steps were effective in inducing hyporheic exchange. However, despite the use of cobbles and boulders in the riffle construction, high stream dissolved oxygen (DO) concentrations were depleted rapidly with depth into the hyporheic zones. Differences between observed and predicted nitrate concentrations based on conservative ion concentration patterns indicated that these hyporheic zones were also nitrate sinks. Zones of low hydraulic conductivity and the occurrence of interstitial fines in the restored cobble-boulder layers suggest that siltation and clogging of the streambed may reduce the downwelling of oxygen- and nitrate-rich stream water. Increases in streambed DO levels and enhancement of habitat for hyporheic fauna that result from riffle–step construction projects may only be temporary in streams that receive increased sediment and nutrient inputs from urban areas and croplands.

Sign in / Sign up

Export Citation Format

Share Document