Elsevier

Geomorphology

Volume 259, 15 April 2016, Pages 70-80
Geomorphology

Variation in reach-scale hydraulic conductivity of streambeds

https://doi.org/10.1016/j.geomorph.2016.02.001Get rights and content

Highlights

  • We compared hydraulic conductivity of streambed sediments in 119 surveys across 83 mostly coarse-bed stream reaches in France.

  • Hydraulic conductivity, even of coarse bed streams, was characteristic of sand and finer sediments.

  • Hydraulic conductivity increased with bedform amplitude, channel width-depth ratio, catchment erodibility and stream power

  • Hydraulic conductivity decreased with time since the last bed disturbance.

  • Streams with a predominantly suspended load and less frequent streambed disturbances had lower hydraulic conductivity.

Abstract

Streambed hydraulic conductivity is an important control on flow within the hyporheic zone, affecting hydrological, ecological, and biogeochemical processes essential to river ecosystem function. Despite many published field measurements, few empirical studies examine the drivers of spatial and temporal variations in streambed hydraulic conductivity. Reach-averaged hydraulic conductivity estimated for 119 surveys in 83 stream reaches across continental France, even of coarse bed streams, are shown to be characteristic of sand and finer sediments. This supports a model where processes leading to the accumulation of finer sediments within streambeds largely control hydraulic conductivity rather than the size of the coarse bed sediment fraction. After describing a conceptual model of relevant processes, we fit an empirical model relating hydraulic conductivity to candidate geomorphic and hydraulic drivers. The fitted model explains 72% of the deviance in hydraulic conductivity (and 30% using an external cross-validation). Reach hydraulic conductivity increases with the amplitude of bedforms within the reach, the bankfull channel width-depth ratio, stream power and upstream catchment erodibility but reduces with time since the last streambed disturbance. The correlation between hydraulic conductivity and time since a streambed mobilisation event is likely a consequence of clogging processes. Streams with a predominantly suspended load and less frequent streambed disturbances are expected to have a lower streambed hydraulic conductivity and reduced hyporheic fluxes. This study suggests a close link between streambed sediment transport dynamics and connectivity between surface water and the hyporheic zone.

Introduction

Hyporheic zones (HZs) are the saturated sediments beneath and adjacent to river channels through which surface water exchanges and mixes with groundwater (White, 1993, Boulton et al., 2010). The HZ is a unique ecotone that supports a variety of hydrological, ecological and biogeochemical processes essential to river ecosystem function (Gibert et al., 1990, Boulton et al., 2010). By regulating the transfer of heat and mass across the sediment–water interface, the HZs play a critical role in temperature buffering (Arrigoni et al., 2008) and biogeochemical cycling (Mulholland and Webster, 2010). They are also permanent habitats for many microbes and invertebrates (Brunke and Gonser, 1999), provide refugia for surface invertebrates or fish (Dole-Olivier, 2011, Kawanishi et al., 2013), and are used by some fish for spawning (Geist et al., 2002). The occurrence and magnitude of processes occurring in HZs largely depend upon the hydrological flux between surface and ground waters (Findlay, 1995, Fischer et al., 2005).

Most laboratory-, field-, and model-based research of hyporheic zone processes has been at the scale of a short river reach (up to several meander wavelengths) or smaller, but efforts to scale up this research to an entire river catchment are very rare (Kiel and Cardenas, 2014). Such efforts will require an understanding of catchment-scale variations in the hyporheic flow regimes including hyporheic flux, residence time, and geometry of flow paths. These are largely determined by variations in pressure at the sediment–water interface and hyporheic zone/groundwater boundary, by bed mobility, and by the variable hydraulic conductivity of porous boundary material (Blaschke et al., 2003). In turn, all these factors vary with river hydrology, channel morphology, and associated fluvial processes (Malard et al., 2002, Tonina and Buffington, 2009).

Although measurements of streambed conductivity have been reported from a broad range of stream types, few empirical studies link spatial (between sites) and temporal (with time) variations in streambed hydraulic conductivity to flow, catchment characteristics, and other geomorphic drivers. Point measurements of streambed hydraulic conductivity found in the literature vary between 10−10 and 10−2 m/s (Calver, 2001), and reach-average values are between 10−5 and 10−3 m/s (Genereux et al., 2008, Song et al., 2009, Chen, 2010, Cheng et al., 2010, Min et al., 2012, Taylor et al., 2013). This upper limit on reach-average values is an order of magnitude lower than might be expected for a uniform gravel [e.g., the Hazen formula (Hazen, 1892) estimates hydraulic conductivity of 0.04 m/s for particle size diameters of 2 mm]. This is because streambed sediments generally have a broad distribution of particle sizes and because hydraulic conductivity is largely determined by the smaller size fractions (Alyamani and Sen, 1993, Song et al., 2009, Descloux et al., 2010). Consequently, variation in hydraulic conductivity between reaches is likely the result of processes controlling presence of fine sediments in the streambed rather than the coarse fraction. Further, point-scale measurements vary considerably within a reach. In some rivers, sections of streambed may be effectively impermeable but the streambed is rarely impermeable throughout the river channel. The lowest reported value of 10−10 m/s, is five orders of magnitude smaller than the lowest reported reach-average value.

In this study we model spatial and temporal variations in hydraulic conductivity to support advances in our understanding of hyporheic processes and their ecological consequences at the catchment scale. After describing a conceptual model of streambed hydraulic connectivity, we use field data collected in 119 surveys of 83 stream reaches across continental France (Datry et al., 2014) to fit and cross-validate an empirical model of reach-scale conductivity as a function of candidate geomorphic and hydraulic controls.

Section snippets

Conceptual model of streambed hydraulic conductivity

Multiple processes likely influence the presence of fine sediments within the streambed and hence its hydraulic conductivity (Fig. 1). These processes drive fine sediment supply, retention on and within the streambed, and fine sediment removal. Fine sediment is supplied from scour of the upstream streambed or banks, and from erosion within the catchment (Wood and Armitage, 1997). Worldwide, land clearance, logging, and mining have increased catchment fine sediment supply whilst sediment

Study reaches

Between February 2010 and October 2011, 153 field surveys of reach hydraulic conductivity were made across 100 stream sites in France. This field program was part of a study to assess use of sediment hydraulic conductivity as a measure of streambed clogging (Datry et al., 2014). Of these sites, 18 were chosen according to their clogging conditions (9 clogged and 9 unclogged sites, as judged by local water managers). The other 82 sites were selected randomly across nine regions in France (Fig. 3

Results

Hydraulic conductivity varied up to a maximum value of 5.6 × 10 4 m/s across the 119 reaches (Fig. 4). The lower detection limit using this equipment is uncertain, but for our purposes we consider 1.0 × 10 6 m/s to be the lower bound for this method of estimating reach-average values. The distribution of values was skewed toward lower values, and 9% of values were recorded at or below this lower detection limit.

Three comparisons were made between observed reach hydraulic conductivity and modelled

Discussion

The upper limit for the range in kreach values reported in this study (5.6 × 10−4 m/s) is consistent with published values including ranges of: 1.2 × 10−4 to 7.4 × 10−4 (Chen, 2010); 2.0 × 10−4 to 5.5 × 10−4 (Cheng et al., 2010); 0.2 × 104 to 1.3 × 10−4 (Genereux et al., 2008); and 1.3 × 10−4 to 6.6 × 10−4 (Song et al., 2009) (all units in m/s). Despite the dominance of coarse-bed rivers in our study, this upper limit is more than two orders of magnitude lower than hydraulic conductivity expected for well-sorted

Conclusions

Streambed hydraulic conductivity can vary over several orders of magnitude potentially exerting a strong control on spatial and temporal variation in hyporheic flow regimes, including hyporheic flux and residence times. Hydraulic conductivity, even of coarse bed streams, is characteristic of sand and finer sediments indicating that processes of streambed clogging are critical. This empirical study found that hydraulic conductivity depends primarily on reach geometry (increases with bedform

Acknowledgements

The authors are grateful for the thoughtful comments of two anonymous reviewers and the considerable patience and editorial input provided by the Editor-in-Chief Prof. Richard Marston.

Stewardson and Grant acknowledge the support of the Australian Research Council (ARC DP130103619) and the US National Science Foundation Partnerships for International Research and Education (OISE-1243543). Stewardson undertook this research primarily while on study leave and hosted by IRSTEA in Lyon, France.

The

References (78)

  • AlyamaniM.S. et al.

    Determination of hydraulic conductivity from complete grain-size distribution curves

    Ground Water

    (1993)
  • ArrigoniA.S. et al.

    Buffered, lagged, or cooled? Disentangling hyporheic influences on temperature cycles in stream channels

    Water Resour. Res.

    (2008)
  • BattinT.J. et al.

    Linking sediment biofilms, hydrodynamics, and river bed clogging: evidence from a large river

    Microb. Ecol.

    (1999)
  • BaxterC. et al.

    Measuring groundwater-stream water exchange: new techniques for installing minipiezometers and estimating hydraulic conductivity

    Trans. Am. Fish. Soc.

    (2003)
  • BearJ.

    Dynamics of Fluids in Porous Media

    (1972)
  • BlaschkeA.P. et al.

    Clogging processes in hyporheic interstices of an impounded river, the Danube at Vienna, Austria

    Int. Rev. Hydrobiol.

    (2003)
  • BoultonA.J. et al.

    Ecology and management of the hyporheic zone: stream–groundwater interactions of running waters and their floodplains

    J. N. Am. Benthol. Soc.

    (2010)
  • BrunkeM.

    Colmation and depth filtration within streambeds: retention of particles in hyporheic interstices

    Int. Rev. Hydrobiol.

    (1999)
  • BrunkeM. et al.

    Hyporheic invertebrates—the clinal nature of interstitial communities structured by hydrological exchange and environmental gradients

    J. N. Am. Benthol. Soc.

    (1999)
  • ButlerJ.J.J.

    The Design, Performance, and Analysis of Slug Tests

    (1998)
  • CalverA.

    Riverbed permeabilities: information from pooled data

    Ground Water

    (2001)
  • ChandesrisA. et al.

    Système Relationnel d'Audit de l'Hydromorphologie Des Cours d'Eau — Atlas à Large échelle

    (2009)
  • ChenX.

    Depth-dependent hydraulic conductivity distribution patterns of a streambed

    Hydrol. Process.

    (2010)
  • ChengC. et al.

    Statistical distribution of streambed vertical hydraulic conductivity along the Platte River, Nebraska

    Water Resour. Manag.

    (2010)
  • CuiY. et al.

    Theory of fine sediment infiltration into immobile gravel bed

    J. Hydraul. Eng.

    (2008)
  • DatryT. et al.

    Estimation of sediment hydraulic conductivity in river reaches and its potential use to evaluation streambed clogging

    River Res. Appl.

    (2014)
  • DesclouxS. et al.

    Comparison of different techniques to assess surface and subsurface streambed colmation with fine sediments

    Int. Rev. Hydrobiol.

    (2010)
  • R. Development Core Team

    R: A Language and Environment for Statistical Computing, R Foundation for Statistical Computing, Vienna, Austria

  • Dole-OlivierM.J.

    The hyporheic refuge hypothesis reconsidered: a review of hydrological aspects

    Mar. Freshw. Res.

    (2011)
  • ElithJ. et al.

    A working guide to boosted regression trees

    J. Anim. Ecol.

    (2008)
  • ElliottA.H. et al.

    Transfer of nonsorbing solutes to a streambed with bed forms: laboratory experiments

    Water Resour. Res.

    (1997)
  • EvansE. et al.

    Fine sediment infiltration dynamics in a gravel-bed river following a sediment pulse

    River Res. Appl.

    (2014)
  • FindlayS.

    Importance of surface-subsurface exchange in stream ecosystems: the hyporheic zone

    Limnol. Oceanogr.

    (1995)
  • FischerH. et al.

    A river's liver–microbial processes within the hyporheic zone of a large lowland river

    Biochemistry

    (2005)
  • FriedmanJ.H.

    Greedy function approximation: a gradient boosting machine

    Ann. Stat.

    (2001)
  • GeistD.R. et al.

    Physicochemical characteristics of the hyporheic zone affect REDD site selection by chum salmon and fall Chinook salmon in the Columbia River

    N. Am. J. Fish Manag.

    (2002)
  • GibertJ. et al.

    Surface water–groundwater ecotones

  • GobF. et al.

    Un outil de caractérisation hydromorphologique des cours dʼeau pour lʼapplication de la DCE en France (CARHYCE) A tool for the characterisation of the hydromorphology of rivers in line with the application of the European Water framework directive in France (CARHYCE)

    Géomorphol. Relief Processus Environ.

    (2014)
  • GooseffM.N. et al.

    A modelling study of hyporheic exchange pattern and the sequence, size, and spacing of stream bedforms in mountain stream networks, Oregon, USA

    Hydrol. Process.

    (2006)
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