G R O U N D WAT E R–SURFAC E-WATER I NTERAC TIONS
Groundwater–surface-water interactions: perspectives on
the development of the science over the last 20 years
Steven M. Wondzell1,2
1
US Forest Service, Pacific Northwest Research Station, Corvallis Forestry Sciences Laboratory, 3200 SW Jefferson Way, Corvallis,
Oregon 97331 USA
Abstract: Freshwater Science published a special series of papers on groundwater–surface-water (GW-SW) interactions in this issue (2015), marking the anniversary of an earlier special series of papers on the hyporheic
zone published in 1993. In this concluding paper, I compare the 2 special series of papers and use this comparison to examine the development of the science in the years between 1993 and 2015. The 1993 papers marked
the beginning of a period of exponential growth in the study of, and publication of, papers on GW-SW interactions. The 1993 papers tended to be forward looking, proposing conceptual models of GW-SW interactions across stream networks and identifying critical gaps. The 2015 special series of papers contrasts sharply
with that of 1993. Broad issue papers are mostly lacking from the current special series. Instead, the special
series is dominated by papers focusing on process-based or descriptive studies using empirical approaches. This
difference probably stems from major methodological advancements over the past 2 decades that make it possible to study GW-SW interactions with ever greater detail and, thus, allows more complete understanding of
specific processes. In contrast, the authors of the 1993 special series were acutely aware of the paucity of GWSW studies and, thus, posed their conceptual models as hypotheses. Surprisingly, these hypotheses have not been
rigorously tested in the decades since their publication. Perhaps it is time to re-examine such broad conceptual models. There remains a critical need for a holistic understanding of how GW-SW interactions vary among
streams types and sizes and with changes in discharge among seasons or over storm events and how these GWSW interactions influence stream ecosystem processes.
Key words: hyporheic, groundwater, streams, conceptual models, literature review
Hyporheic science has grown dramatically since the word
was defined by Orghidan (1955; from the English translation by D. Käser 2010). Early hyporheic studies were relatively few and tended to focus primarily on the biota inhabiting the shallow stream bed. The signature characteristic
of the hyporheic zone—as an ecotone where stream water
and ground water met and mixed—slowly gained recognition in aquatic ecology, and in the mid- to late-1980s, several landmark papers refocused attention on the potential
effects of the hyporheic zone on broader stream ecological
processes. Grimm and Fisher (1984) published a seminal
work showing that metabolism in hyporheic sediment was
large enough that a stream previously thought to be autotrophic was actually heterotrophic. Stanford and Ward
(1988) described the importance of hyporheic habitats to
stream-dwelling macroinvertebrates at lateral distances of
several kilometers from the stream, a spatial scale never
previously imagined for below (hypo) stream (rheos) pro-
cesses. Triska et al. (1989a, b) showed that the hyporheic
zone played a critical role in the transport and retention
of nutrients in streams. These papers are the most highly
cited early publications on the hyporheic zone (Scopus citation search, May 2014; Scopus, Elsevier, The Netherlands). These papers built on a history of previous research, much of which did not explicitly use the word
“hyporheic” (e.g., Vaux 1962, Thackston and Schnelle 1970,
Chatarpaul and Robinson 1979) and served as landmarks
in the development of a new subdiscipline in hydrology and
stream ecology. In 1993, the Journal of the North American
Benthological Society ( J-NABS) published a special series of
papers on hyporheic science that further established it as a
subdiscipline. The papers that made up that special series
articulated needs and future directions for hyporheic research.
The growth rate of the number of papers published in
the subdiscipline of hyporheic research and the more gen-
E-mail addresses: 2swondzell@fs.fed.us
DOI: 10.1086/679665. Received 5 September 2014; Accepted 3 October 2014; Published online 8 December 2014.
Freshwater Science. 2015. 34(1):000–000. © 2015 by The Society for Freshwater Science.
This content downloaded from 128.193.164.203 on Wed, 17 Dec 2014 14:07:34 PM
All use subject to JSTOR Terms and Conditions
000
2
|
Concluding paper to the special series
S. M. Wondzell
eral discipline of groundwater–surface-water (GW-SW)
interactions has been approximately exponential since the
mid-1980s (Fig. 1A). From its first use through the end of
1993, Scopus lists a cumulative total of only 55 citations
using the word “hyporheic” in the title, abstract, or list of
key words. As of May 2014, a cumulative total of 1200 citations, of which 135 were published in 2013 alone, was
found by searching on “hyporheic” as a key word (Fig. 1B).
Furthermore, the rate of growth in the number of publications in these fields has been 1.6 and 1.3× greater, respectively, than the growth of publications in the Scopus
database at large (Fig. 1A). An examination of the titles
of papers in this literature search indicates that early hyporheic research tended to be somewhat narrowly focused
on stream–shallow groundwater interactions. Publications
in the larger field of GW-SW interactions began to appear
Figure 1. A.—Semilog plot of the number of papers published each year including the word “hyporheic” in the title, abstract, or
keywords (all hyporheic) vs those including either “hyporheic” or “surface water AND groundwater AND (interaction OR interactions)”
compared to the growth in the number of papers published in the Scopus database at large. Linear regressions fit these lines with all
r 2 > 0.92. Slopes are 0.086 (hyporheic), 0.070 (groundwater–surface-water [GW-SW], and hyporheic), and 0.053 (all Scopus citations).
B.—Total number of papers published each year in 3 subdisciplines of hydrology.
This content downloaded from 128.193.164.203 on Wed, 17 Dec 2014 14:07:34 PM
All use subject to JSTOR Terms and Conditions
Volume 34
in the Scopus database at approximately the same time as
those reporting hyporheic research, but the GW-SW publications tended to focus on interactions between rivers and
groundwater aquifers at larger scales more relevant to human social and economic systems. Only recently has the
scope of research in stream ecology and hyporheic processes
broadened to examine the full catchment continuum (Bencala et al. 2011) that influences the hydrology and ecology of
streams, hyporheic zones, and both shallow near-stream
unconstrained aquifers and larger regional aquifers. This
expansion of the science is reflected in the descriptive terminology, with the phrase “stream-water–groundwater interactions” increasingly replacing “hyporheic” in the literature (Fig. 1B).
The 1993 special series
The 1993 special series of papers ( J-NABS, volume 12,
issue 1) was published immediately before the explosion of
hyporheic research (Fig. 1B), and thus, was timely. Perhaps
the tone of the special series was described best by David
White who reflected on the relative newness of hyporheic
research and wrote: “. . . there is danger in making sweeping generalizations with so few hyporheic zones having
been examined comparatively. However, perhaps one of
the most exciting times in any endeavor is when we are
still at liberty to make some proposals” (White 1993, p. 61).
To that end, the collected papers of the 1993 special series provided an important conceptual context from which
to begin building a more comprehensive understanding of
the hydrological and ecological processes that occur in the
hyporheic zone and the importance of those processes to
stream ecosystems. Furthermore, authors of papers in this
collection raised critical unanswered questions in hopes
that they would guide future research. As a consequence,
many of the papers in the 1993 special series have become
widely cited.
Bencala (1993) challenged common hydrologic perceptions of unidirectional flow of water into and down streams,
which likens them to simple pipes, and instead recognized
the importance of bidirectional exchange in which stream
water can move repeatedly from the stream, into the subsurface, and back into the stream. The simple statement,
“the stream is not a pipe”, reflected a major shift in the
prevailing conceptual models of ecology and hydrology in
the 1980s, but it did little to predict the relative importance
of hyporheic exchange flows to stream ecosystems nor did
it help answer the questions about where, when, and under
what conditions hyporheic exchange flows occur.
Stanford and Ward (1993) and White (1993) endeavored
to build conceptual models describing the relative importance of the hyporheic zone in stream ecosystem processes
along the longitudinal corridor of alluvial rivers, from
headwaters through large mainstem reaches. These efforts
clearly complemented the river continuum concept (Van-
March 2015
|
3
note et al. 1980), which described a systematic progression in processes linked to location and size of the river.
However, Stanford and Ward (1993) and White (1993)
also recognized that spatial heterogeneity in the hydrogeomorphic factors that control the expression of the
hyporheic zone would control the relative importance of
specific hyporheic processes across scales ranging from
the channel unit to stream networks. White (1993) emphasized the importance of developing a common, interdisciplinary framework to support comparisons of hyporheic
processes among different river systems and across scales.
Stanford and Ward’s (1993) conceptual model was heavily
influenced by their work in large, unconstrained reaches
of coarse-bedded mountain rivers, whereas White’s (1993)
conceptual model drew heavily from his work on lowgradient mid-order streams. As a consequence, their conceptual models were somewhat different. For example,
White (1993) hypothesized that little hyporheic exchange
would occur in headwater reaches, which would be dominated by lateral inputs of ground water, whereas Stanford
and Ward (1993) hypothesized that interstitial exchange
in headwaters might be small in absolute terms, but potentially large relative to surface discharge. Both White
(1993) and Stanford and Ward (1993) hypothesized that
hyporheic exchange would be maximal relative to stream
discharge in mid-order reaches and that the alluvial floodplains of larger rivers might well be dominated by hyporheic
waters.
The papers by Hendricks (1993) and Stanley and Boulton
(1993) examined spatial patterning of the hyporheic zone
caused by characteristic hydrological flow paths through
pool–riffle sequences and point bars and the resulting
boundaries between ground water and hyporheic water.
Hendricks’ (1993) paper summarized several years of published and unpublished research and provided one of the
first multidisciplinary summaries of hyporheic processes
including the density of invertebrates, microbial biomass
and production, microenvironmental gradients in water
chemistry, and basic geochemical processes in both aerobic
and anaerobic zones. Stanley and Boulton (1993) showed
that spatial patterns of subsurface invertebrates were closely
related to patterns of groundwater upwelling and hyporheic
downwelling in a mesic temperate river and an intermittent
desert river and that temporal variations in these patterns
caused by spates or drying also could be explained by hydrologic patterns. Together, these papers demonstrated the
fundamental control that hydrology exerts on hyporheic
processes and the importance of spatial heterogeneity
from the microscale of biofilms on sediment surfaces to the
channel-unit scale at which hyporheic upwelling and downwelling were organized.
Authors of papers in the 1993 special series also identified a number of unresolved issues that limited understanding of hyporheic processes and their influences on
stream ecosystems. For example, Palmer (1993) identified
This content downloaded from 128.193.164.203 on Wed, 17 Dec 2014 14:07:34 PM
All use subject to JSTOR Terms and Conditions
4
|
Concluding paper to the special series
S. M. Wondzell
major obstacles limiting research on the hyporheic zone
and attempted to suggest approaches that could break
through these obstacles, leading to major advances in the understanding of hyporheic processes. These included: 1) embracing the intersite heterogeneity of the hyporheic zone
and working to understand the factors that control hyporheic
processes among different sizes and types of streams;
2) developing better sampling tools and methods; 3) considering the role of bed movement, sediment transport,
and infrequent hydrologic events; 4) measuring subsurface
flow velocities; and 5) quantifying the magnitude and direction of fluxes between surface stream, hyporheic zone,
and groundwater environments.
The 2015 special series
The collection of papers in this 2015 special series provides a stark contrast to those published in 1993. Perhaps
the most obvious difference is the absence of broad-issue
papers. A number of potential reasons exist to explain
this difference. Foremost among these is that the contributing authors were not specifically asked to address broad
issues, such as the current state of the science, or to identify critical unresolved issues. At the same time, the collection of papers in the 2015 special series provides a
broad sampling of current research into GW-SW interactions. Thus, comparisons to the collection of papers from
1993 may prove informative.
Undoubtedly, the newness of hyporheic science in 1993
enabled authors to build initial conceptual models around
which individual studies could be organized to develop a
more holistic understanding of the role of the hyporheic
zone in stream ecosystem processes. The increased maturity of the field today creates a different publication environment, but also provides opportunities to evaluate the
current state of knowledge and reassess topics that are
important for future research. Several recent literature reviews (e.g., Sophocleous 2002, Boulton et al. 2010, Krause
et al. 2011) fill this need, but I suspect that the content of
the papers in the 2015 special series broadly reflects developments in the field over the past few decades, i.e., a
strong focus on process-based research. This focus on
process-based research arose, at least in part, from development and increasing accessibility of better technological approaches, e.g., fiber-optic distributed temperature-sensing
technology (Selker et al. 2006), stable-isotope approaches
(Böhlke et al. 2004), and computational capacity that makes
numerical modeling with computational fluid dynamics
models relatively accessible (Cardenas et al. 2004). These
developments allow in-depth investigation into the mechanisms of hydrological and biogeochemical processes at
relatively fine spatial and temporal scales, but larger-scale
questions, many of which were raised in the 1993 special
series, have received less attention.
Papers in the 2015 series can be broadly divided into
3 groups: 1) empirical, process-based studies of stream–
groundwater interactions, 2) descriptive studies of the distribution of groundwater fauna, and 3) methods papers
(Table 1).
The first group of papers, consisting of the processbased studies of stream–groundwater interactions, clearly
follow the conceptual approaches put forth in the 1993
special series. Authors of these papers tended to focus at
the reach-scale (8 of 10 papers; study topic = S or S/G in
Table 1) and studied relatively small streams (median watershed size is 42 km2; Table 1) at low discharge (Q; median of both low and high Q = 65 L/s; Table 1). Temporal
scales were more broadly represented, and studies addressed changes occurring over hours, days, seasons, and
even between years. Two-thirds of these papers explored
hydrological processes, sometimes alone but also in association with studies of biogeochemical processes (Table 1).
Biogeochemical studies were focused primarily on N and
C, but the advent of reliable and relatively inexpensive datalogging multisensors led to temperature, electrical conductivity, pH, and dissolved O2 becoming common metrics in
study-site descriptions or covariates in analyses. Notably
absent from this subset of the 2015 papers are studies
at the scales of sediment grains and biofilms, and only
1 study was conducted at the multi-reach to network scale.
Although many authors in the series addressed biogeochemical processes, only 1 author attempted to develop
budgets of mass fluxes at reach or larger scales (Zarnetske
et al. 2015).
Unlike the 1993 special series, ∼⅓ of the papers in the
2015 special series focused on groundwater fauna and the
ecological relationships in larger aquifer systems (study
topic = G, Table 1). This 2nd group of papers signifies the
increased emphasis on the full complement of ecohydrologic systems that compose GW-SW interactions. In 1993,
the hyporheic zone was so novel that the special series
focused solely on those small spatial and short temporal
scales at which stream water flowed through the stream
bed, into alluvial sediment, and would soon return to the
stream. The field has grown to recognize the importance
of larger groundwater systems that need to be included as
part of the continuum of these interactions. Groundwaterrelated studies in the 2015 special series range over spatial
scales from local streamside aquifers to regional aquifers
(Table 1). For example, seepage through the beds of rivers
can recharge large aquifers so that distance from the river
may be a primary influence on groundwater chemistry and
the distribution of organisms found in these groundwater
systems (e.g., Larned et al. 2015). Conversely, aquifer recharge may be dominated by precipitation so that spatial
patterns in the overlying soils and regional geology may
determine the distribution of organisms found in groundwater systems (Johns et al. 2015, Korbel and Hose 2015).
This content downloaded from 128.193.164.203 on Wed, 17 Dec 2014 14:07:34 PM
All use subject to JSTOR Terms and Conditions
This content downloaded from 128.193.164.203 on Wed, 17 Dec 2014 14:07:34 PM
All use subject to JSTOR Terms and Conditions
S
S
S
S
S
W
G
G
G
G
G
G
M
Rinehart et al.
Stubbington et al.
Vasquez et al.
Zarnetske et al.
Zimmer and Lutz
Larson et al.
Griebler and
Avramov
Johns et al.
Korbel and Hose
Larned et al.
Stelzer et al.
Tristram et al.
Aubeneau et al.
S/M
S
S
Kurz et al.
Menichino et al.
S
Ganong et al.
GonzalesPinzon et al.
S/G
S/G
Study topic
Caldwell et al.
Ebersole et al.
% in category/
medians
Authors
Simulation
Restoration
Refugia
Ground water
Empirical
Hyporheic
Other nutrient
Trophic relations
Biofilms
Biota
Biodiversity
C=Organic matter
Phosphorus
Conservative tracers
Reactive tracers
Dissolved O2
Nitrogen
EC
pH
Floods
Droughts
Temperature
Weeks
Seasons
Years
Channel morphology
Hydrological
Hours
Diel
Days
Multiscale
Single measurement
Other
Single scale
Reach
Network=watershed
Local aquifer
Regional aquifer
Channel unit
Particle
Subunit
X
x
x
X
X
x
X
x X
x X
X
X
x
x X
X
X
X
x
X
X
x X
x
X x
x
x
x
X
x
x
x
x
x
X x
X
x
x
x
X
X
X x
x X
x
x
x X
x
x
x
x X
x
X x
X x
x
x
X x
X
X
x
x
X X
x X
X
X
x
x
x X
X
X
X
x
x
X
X
X
x
X
x
X
x
x
x
x
x
x
x
x
x
x x
X
X x
x X
X
x x
X
X
x x
X
x
x
x
x
x
x
X X
x
x
x
X X
X
x
X X
x
x
x
x
x
x
x
x
x
X X X
x
x
x
X X
x
x
x
X
x
x X
x X x
x
x
x
x X X x
x
x
x
x
x
X
x
X
X X
x
X
X x
X
X X
X
X X
X x
X X
X X
X X
X
X
X
x
X
X X X X X
X
X X X
X
X X
X X
x x x
X
X X
X X X
X x
X
x
X x
x
x X
x
X
X
X
0 20 30 50 5 30 10 10 45 50 20 20 5 25 10 65 25 0 60 10 15 45 35 30 25 15 45 50 50 30 25 0 0 25 15 45 60 85 25 10 10 10 20 5 15
Patch
Special topic
Pollution
Ecosystem services
Type of
study
Median physical attributes
of stream studies
27
138
222
3
3
1
42
18.1
0.37
n/a
35
510
22
800
22
181 181
0.1 95
35
3
3
3
1
26,500
750
65.17
213
16.2
5.2
5700 14,300
960
3.3
3.3 2.5
206
26.3 191.5
23.9
31
Low Q ðL=sÞ
Topic or variables studied
High Q ðL=sÞ
Temporal scale
Stream order
Spatial scale
Methods
Table 1. A summary of the papers in this special series (2015). X denotes a primary focus of the study, and x denotes a secondary focus. Papers are categorized by dominant study topic
(S = stream, G = ground water, W = wetland, M = methods), spatial scale, temporal scale, and topic or variables studied. Studies are identified as focused primarily on hyporheic or groundwater systems and as empirical or simulation studies. A few papers address narrow topics (as listed). Physical attributes of the study sites are summarized for the papers that reported them.
The percentage of the 20 papers in a category is given in the top row, except for the last 4 columns where median values of physical attributes for stream-focused studies are reported. Not all
papers were easily categorized, and many studies spanned >1 category or did not fit any category. Q = discharge and EC = electrical conductivity.
Watershed area ðkm2 Þ
6
|
Concluding paper to the special series
S. M. Wondzell
Discharge of long-residence-time ground waters from regional aquifers into streams can have major influences on
stream ecosystem processes (e.g., Kurz et al. 2015), and of
course, biogeochemical processes in these large groundwater systems influence water quality for anthropogenic
uses and, thus, represent an environmental service (Griebler
and Avramov 2015). Studies at the scales of large floodplain aquifers to regional aquifers are difficult because access to these systems requires deep wells. As a consequence,
such studies are relatively rare and those published here
are mostly descriptive (Johns et al. 2015, Korbel and Hose
2015, Larned et al. 2015).
Several authors in the 2015 special series explored methodological approaches to studying GW-SW interactions
(study topic = M or S/M, Table 1). These papers are quite
different in approach than the methods paper in the 1993
special series (Palmer 1993), which was forward looking
and attempted to identify methods developments needed
to make progress in the newly developing field. Authors
of the subset of methods papers in the 2015 special series
tended to examine existing methodological approaches and
the limitations of these approaches. Tracer studies have
been a mainstay of hyporheic research since their introduction to the stream ecology community by Bencala and
Walters (1983) and the Stream Solute Workshop (1990).
Modified 1-dimensional advection–dispersion models were
initially developed by engineers to describe flow and transport in pipes (Taylor 1954, as cited by Thackston and
Schnelle 1970), but when applied to streams, they failed to
capture the shape of the breakthrough curve and, thus,
were modified by adding a transient-storage component.
The same models were further modified to include 1storder reactions to describe the transport, retention, and
transformation of reactive solutes. Transient-storage modeling has been used widely since the early 1990s. However,
over the last few years, several authors have begun to
question the applicability of these methods for understanding GW-SW interactions, especially at the time- and
space-scales that are captured in such tracer tests (e.g.,
Zarnetske et al. 2015). Aubeneau et al. (2015) provided an
in-depth analysis of the shape of hypothetical breakthrough
curves, based on continuous-time, random-walk models,
to examine the influence of a variety of benthic and hyporheic processes. González-Pinzón et al. (2015) reported
the results of a multi-investigator, multitechnique analysis
of GW-SW interactions conducted as a part of a workshop. Their study was unique in that they field-tested and
compared multiple techniques simultaneously in a single
stream reach, and they discussed the advantages and limitations of each technique. Many methodological improvements have occurred in the field since the 1993 special
series, but it remains difficult to work across scales. Specifically, linking local point measurements or channel-unit
measurements to describe reach-scale processes or to
scale-up reach-scale measurement to the whole-stream
network is challenging (e.g., Zarnetske et al. 2015).
Unaddressed issues and future directions
Hakenkamp et al. (1993) summarized the collection of
papers in the 1993 special series and identified a number
of important questions for future research. When one
considers the 1993 special series more broadly, the authors of the collected papers clearly were acutely aware
of the paucity of hyporheic studies and, thus, posed their
conceptual models as hypotheses based on their own observations at one or a few sites or, in some cases, a comparison of their results with a small number of similar
studies. It is interesting to look at the research accomplished in the intervening years and ask which of those
conceptual models found strong support in the literature, which have been revised or modified on the basis of
new results, which areas have seen substantial progress,
and which have seen relatively little progress.
Many hyporheic processes are controlled by interactions between water flowing through individual pores and
biogeochemical processes occurring in biofilms coating particles of hyporheic sediment. Hendricks (1993) studied finescale organismal processes, especially those mediated by
microbial biofilms that explained the outcomes of GW-SW
interactions at reach and larger scales. However, since then
studies at the pore or biofilm scale have been relatively
uncommon. The ecological and physical processes occurring at these fine spatial scales simply cannot be resolved
by the methods most frequently used in the field. Subsurface environments are heterogeneous, and preferential
flow might be a critical determinant of the actual influence that exchange flows exert. Improved computing power
allows ever more powerful models to be run at finer and
finer spatial resolution, but the ability to incorporate spatial heterogeneity into these models is limited by at least
2 factors. First, spatial properties do not scale continuously
from micro to macro scales. Thus, grid/mesh spacing will
become smaller than the size of the clasts that compose
the dominant physical framework of the porous medium
through which both surface stream water and ground water flow. Second, the spatial heterogeneity of the subsurface cannot be measured at the range of spatial scales
relevant to understanding biological and hydrological processes. Thus, representing these processes in models, regardless how fine-grained the model, is challenging.
Investigators are beginning to explore alternative approaches. For example, relatively immobile domains within
the subsurface, where solute transport is controlled by
molecular-scale diffusion (Hadley and Newell 2014) rather
than advection–dispersion processes, may be critically important to understanding solute transport. The influence
of these relatively immobile domains on solute transport
also is being explored with dual-domain mass-transfer
This content downloaded from 128.193.164.203 on Wed, 17 Dec 2014 14:07:34 PM
All use subject to JSTOR Terms and Conditions
Volume 34
models (Haws et al. 2004) and versions of these models
have been applied to flow-through porous media as influenced by biofilms (Seifert and Engesgaard 2007, Orgogozo
et al. 2013), but these models have not been applied to
studies of GW-SW interactions. Other modeling approaches
are beginning to be used to explore the turbulence structures that develop with flow through pores between idealized spherical grains (e.g., Finn and Apte 2013). However, these models do not yet simulate the presences of
biofilms coating mixtures of sediment grains with a heterogeneous distribution of sizes, factors that would be critically
important to understanding the delivery of solutes to biofilms. Nevertheless, these are the scales at which many of
the processes of interest are occurring. The range of spatial
and temporal scales involved in these processes create
significant challenges for investigators attempting to accurately characterize processes at the scale of cells and
biofilms and to upscale these processes to predict system
responses at whole-watershed or regional-aquifer scales.
White (1993) and Stanford and Ward (1993) began developing conceptual foundations on which to frame our
understanding of stream–groundwater interactions and
from which the potential role of surface–groundwater exchanges could be evaluated at the scale of whole stream
networks. Geomorphology-based classification of streams,
such as that published by Montgomery and Buffington
(1998), would provide a reasonable starting point for developing such a framework. The geomorphic classification
has proven useful for understanding fluvial-process domains (Montgomery 1999) and how they influence biologically important attributes (Buffington et al. 2004). Little
progress has been made in developing a similar framework to organize conceptual models of processes controlling GW-SW interactions and their influence on stream
and groundwater ecosystems. This problem is well illustrated in the 2015 special issue. None of the authors provided a comparative study of how geomorphic factors,
especially channel morphology, influence GW-SW interactions. In fact, the authors generally did not describe the
physical setting of the streams they studied. This omission
makes it difficult to draw broad generalizations about the
importance of different processes among stream types.
The organizers of the 1993 special series stated that “each
hyporheic system is unique, but cross-system comparisons
may be possible . . .” (Hakenkamp et al. 1993, p. 97). A critical need exists to develop a rigorous taxonomic system
within which the results of the many reach-scale studies
can be organized conceptually so that broader generalizations can be made.
The 1993 special series was a watershed event in the
field—one highlighted by Bencala’s figure challenging conventional wisdom that “a stream is not a pipe”. Today, this
idea is so deeply entrenched that statements that GW-SW
interactions are important in stream ecosystem processes
March 2015
|
7
are accepted as common knowledge and, thus, seldom receive critical examination. However, evidence is increasing
that, in some stream reaches under some conditions and
for some processes of interest, GW-SW exchanges have
little-to-no influence on the properties of the bulk of stream
water (Burkholder et al. 2008, Wondzell 2011). Under such
conditions, streams serve primarily to convey water, solutes, and suspended materials downstream. The conceptual ideas presented by Bencala (1993), Stanford and Ward
(1993), and White (1993) all deserve critical examination:
When and where are streams not pipes? When and where
do they really function as pipes, and for what materials or
processes? The conceptual models presented by Stanford
and Ward (1993) or White (1993) deserve to be critically
tested.
Geomorphology, hydrology, biogeochemistry, and ecology can provide a descriptive framework within which
understanding the relative importance of stream–groundwater interactions among the types of streams and across
the range of flow conditions that occur in these streams
might be possible. However, building such a framework
will not be simple. Moreover, the stream reach provides a
tractable scale for small research groups involved in studies of one to a few years duration, but such studies do not
appear to have been sufficient to build or test such a framework. I see a few possible ways forward. The first would
be akin to a meta-analysis approach in which smaller individual studies could be summarized across broad spatial
scales for a more holistic understanding. However, such
an approach would require that the smaller studies provide sufficient information and use sufficiently comparable
techniques that reasonable comparative analyses could be
conducted. Alternatively, resources for studies of stream–
groundwater interactions could be invested in larger,
multi-investigator, multisite, and multidisciplinary studies
that could use a systematic approach in a manner akin to
the Lotic Intersite Nitrogen eXperiments (LINX I and II;
Webster et al. 2003, Mulholland et al. 2008, Dodds et al.
2014). In any event, growth in our understanding of GWSW interactions will require new, holistic approaches that
supersede the approaches used to date.
The science of hyporheic processes, and more broadly,
GW-SW interactions, has progressed substantially over the
last 20 y as evidenced by the growth in the published literature (Fig. 1A, B) and the comparison between the 1993 and
the 2015 special series. Despite this progress, many of the
larger issues posed by the authors of the 1993 special series remain as critical challenges for the study of GW-SW
interactions. Answering these questions would help develop
a holistic understanding of how GW-SW interactions vary
among stream types and sizes and with changes in discharge among seasons or over storm events and would en
able a deeper understanding of the role that GW-SW interactions play in the ecology of surface and ground waters.
This content downloaded from 128.193.164.203 on Wed, 17 Dec 2014 14:07:34 PM
All use subject to JSTOR Terms and Conditions
8
|
Concluding paper to the special series
S. M. Wondzell
L I T E R AT U R E CI T E D
Papers from the 1993 special series are denoted with an asterisk. Papers from the 2015 special series are in bold.
Aubeneau, A. F., J. D. Drummond, R. Schumer, D. Bolster,
J. L. Tank, and A. I. Packman. 2015. Effects of benthic and
hyporheic reactive transport on breakthrough curves. Freshwater Science 34:XXX–XXX.
*Bencala, K. E. 1993. A perspective on stream–catchment connections. Journal of the North American Benthological Society 12:44–47.
Bencala, K. E., M. E. Gooseff, and B. A. Kimball. 2011. Rethinking hyporheic flow and transient storage to advance understanding of stream-catchment connections. Water Resources
Research 47:W00H03.
Bencala, K. E., and R. A. Walters. 1983. Simulation of solute transport in a mountain pool-and-riffle stream: a transient storage
model. Water Resources Research 19:718–724.
Böhlke, J. K., J. W. Harvey, and M. A. Voytek. 2004. Reach-scale
isotope tracer experiment to quantify denitrification and related processes in a nitrate-rich stream, midcontinent United
States. Limnology and Oceanography 49:821–838.
Boulton, A. J., T. Datry, T. Kasahara, M. Mutz, and J. A. Stanford. 2010. Ecology and management of the hyporheic zone:
stream–groundwater interactions of running waters and their
floodplains. Journal of the North American Benthological Society 29:26–40.
Buffington, J. M., D. R. Montgomery, and H. M. Greenberg.
2004. Basin-scale availability of salmonid spawning gravel as
influenced by channel type and hydraulic roughness in mountain catchments. Canadian Journal of Fisheries and Aquatic
Sciences 61:2085–2096.
Burkholder, B. K., G. E. Grant, R. Haggerty, T. Khangaonkar, and
P. J. Wampler. 2008. Influence of hyporheic flow and geomorphology on temperature of a large, gravel-bed river, Clackamas
River, Oregon, USA. Hydrological Processes 22:941–953.
Caldwell, S. K., M. Peipoch, and H. M. Valett. 2015. Spatial
drivers of ecosystem structure and function in a floodplain
riverscape: springbrook nutrient dynamics. Freshwater Science 34:XXX–XXX.
Cardenas, M. B., J. L. Wilson, and V. A. Zlotnik. 2004. Impact
of heterogeneity, bed forms, and stream curvature on subchannel hyporheic exchange. Water Resources Research 40:
W08307.
Chatarpaul, L., and J. B. Robinson. 1979. Nitrogen transformations in stream sediments: 15N studies. Pages 119–127 in
C. D. Litchfield and P. L. Seyfried (editors). Methodology for
biomass determinations and microbial activities in sediments.
ASTM STP 673. American Society for Testing and Material
673:119–127.
Dodds, W. K., J. R. Webster, C. L. Crenshaw, A. M. Helton, J. M.
O’Brien, E. Martí, A. Hershey, J. L. Tank, A. J. Burgin, N. B.
Grimm, S. K. Hamilton, D. J. Sobota, G. C. Poole, J. J. Beaulieu, L. T. Johnson, L. R. Ashkenas, R. O. Hall, S. L. Johnson,
W. M. Wollheim, and W. B. Bowden. 2014. The Lotic
Intersite Nitrogen Experiments: an example of successful ecological research collaboration. Freshwater Science 33:700–
710.
Finn, J., and S. V. Apte. 2013. Relative performance of body fitted
and fictitious domain simulations of flow through fixed packed
beds of spheres. International Journal of Multiphase Flow 56:
54–71,
Ebersole, J. L., P. J. Wigington, S. G. Leibowitz, R. L. Comeleo,
and J. Van Sickle. 2015. Predicting the occurrence of coldwater patches at intermittent and ephemeral tributary confluences with warm rivers. Freshwater Science 34:XXX–XXX.
Ganong, C. N., G. E. Small, M. Ardón, W. H. McDowell,
D. Genereux, J. H. Duff, and C. M. Pringle. 2015. Interbasin transfers of geothermally modified ground water alter
stream nutrient fluxes: an example from lowland Costa Rica
in a global context. Freshwater Science 34:XXX–XXX.
González-Pinzón, R., A. S. Ward, C. E. Hatch, A. N.
Wlostowski, K. Singha, M. N. Gooseff, R. Haggerty, J. W.
Harvey, O. A. Cirpka, and J. T. Brock. 2015. Techniques to
quantify surface-water–groundwater interactions and shallow subsurface transport. Freshwater Science 34:XXX–XXX.
Griebler, C., and M. Avramov. 2015. Groundwater ecosystem
services: a review. Freshwater Science 34:XXX–XXX.
Grimm, N. B., and S. G. Fisher. 1984. Exchange between interstitial and surface water: implications for stream metabolism
and nutrient cycling. Hydrobiologia 111:219–228.
Hadley, P. W., and C. Newell. 2014. The new potential for understanding groundwater contaminant transport. Groundwater 52:
174–186.
*Hakenkamp, C. C., H. M. Valett, and A. J. Boulton. 1993.
Perspectives on the hyporheic zone: integrating hydrology and
biology. Concluding remarks. Journal of the North American
Benthological Society 12:94–99.
Haws, N. W., B. S. Das, and P. S. C. Rao. 2004. Dual-domain
solute transfer and transport processes: evaluation in batch
and transport experiments. Journal of Contaminant Hydrology
75:257–280.
*Hendricks, S. P. 1993. Microbial ecology of the hyporheic
zone: a perspective integrating hydrology and biology. Journal of the North American Benthological Society 12:70–78.
Johns, T., J. I. Jones, L. Knight, L. Maurice, P. Wood, and
A. Robertson. 2015. Regional-scale drivers of groundwater
faunal distributions. Freshwater Science 34:XXX–XXX.
Korbel, K. L., and G. C. Hose. 2015. Water quality, habitat, site,
or climate? Identifying environmental correlates of the distribution of groundwater biota. Freshwater Science 34:XXX–
XXX.
Krause, S., D. M. Hannah, J. H. Fleckenstein, C. M. Heppell, D.
Kaeser, R. Pickup, G. Pinay, A. L. Robertson, and P. J. Wood.
2011. Inter-disciplinary perspectives on processes in the
hyporheic zone. Ecohydrology 4:481–499.
Kurz, M. J., J. B. Martin, M. J. Cohen, and R. T. Hensley.
2015. Diffusion-dominated fluxes from the hyporheic zone:
implications for metal and nutrient availability in streams. Freshwater Science 34:XXX–XXX.
Larned, S. T., M. J. Unwin, and N. C. Boustead. 2015. Ecological dynamics in riverine aquifers of a gaining and losing
river. Freshwater Science 34:XXX–XXX.
Larsen, L. G., J. W. Harvey, and M. M. Maglio. 2015. Mechanisms of nutrient retention and its relation to flow connectivity in river–floodplain corridors. Freshwater Science 34:
XXX–XXX.
Menichino, G. T., D. T. Scott, and E. T. Hester. 2015. Abundance and dimensions of naturally occurring macropores
This content downloaded from 128.193.164.203 on Wed, 17 Dec 2014 14:07:34 PM
All use subject to JSTOR Terms and Conditions
Volume 34
along stream channels and the effects of artificially constructed large macropores on transient storage. Freshwater
Science 34:XXX–XXX.
Montgomery, D. R. 1999. Process domains and the river continuum. Journal of the American Water Resources Association 35:397–410.
Montgomery, D. R., and J. M. Buffington. 1998. Channel processes,
classification, and response. Pages 13–42 in R. J. Naiman
and R. E. Bilby (editors). River ecology and management: lessons from the Pacific Coastal ecoregion. Springer–Verlag, New
York.
Mulholland, P. J., A. M. Helton, G. C. Poole, R. O. Hall, S. K.
Hamilton, B. J. Peterson, J. L. Tank, L. R. Ashkenas, L. W.
Cooper, C. N. Dahm, W. K. Dodds, S. E. G. Findlay, S. V. Gregory, N. B. Grimm, S. L. Johnson, W. H. McDowell, J. L. Meyer,
H. M. Valett, J. R. Webster, C. P. Arango, J. J. Beaulieu, M. J.
Bernot, A. J. Burgin, C. L. Crenshaw, L. T. Johnson, B. R.
Niederlehner, J. M. O’Brien, J. D. Potter, R. W. Sheibley, D. J.
Sobota, and S. M. Thomas. 2008. Stream denitrification across
biomes and its response to anthropogenic nitrate loading. Nature 452:202–205.
Orghidan, T. 1955 (translated into English by Käser, 2010). A new
habitat of subsurface waters: the hyporheic biotope. Fundamental and Applied Limnology 176:291–302.
Orgogozo, L., F. Golfier, M. A. Buès, M. Quintard, and T. Koné.
2013. A dual-porosity theory for solute transport in biofilmcoated porous media. Advances in Water Resources 62:266–
279.
*Palmer, M. A. 1993. Experimentation in the hyporheic zone:
challenges and prospectus. Journal of the North American
Benthological Society 12:84–93.
Rinehart, A. J., J. B. Jones, and T. K. Harms. 2015. Hydrologic
and biogeochemical influences on carbon processing in the
riparian zone of a subarctic stream. Freshwater Science 34:
XXX–XXX.
Seifert, D., and P. Engesgaard. 2007. Use of tracer tests to investigate changes in flow and transport properties due to
bioclogging of porous media. Journal of Contaminant Hydrology 93:58–71.
Selker, J., N. van de Giesen, M. Westhoff, W. Luxemburg, and
M. B. Parlange. 2006. Fiber optics opens a window on stream
dynamics. Geophysical Research Letters 33:L24401.
Sophocleous, M. 2002. Interactions between groundwater and
surface water: the state of the science. Hydrogeology Journal
10:52–67.
Stanford, J. A., and J. V. Ward. 1988. The hyporheic habitat of
river ecosystems. Nature 335:64–66.
*Stanford, J. A., and J. V. Ward. 1993. An ecosystem perspective of alluvial rivers: connectivity and the hyporheic corridor. Journal of the North American Benthological Society
12:48–60.
*Stanley, E. H., and A. J. Boulton. 1993. Hydrology and the distribution of hyporheos: perspectives from a mesic river and a desert stream. Journal of the North American Benthological Society 12:79–83.
Stelzer, R. S., J. T. Scott, and L. A. Bartsch. 2015. Buried
particulate organic carbon stimulates denitrification and nitrate retention in stream sediments at the groundwater–
surface-water interface. Freshwater Science 34:XXX–XXX.
March 2015
|
9
Stream Solute Workshop. 1990. Concepts and methods for assessing solute dynamics in stream ecosystems. Journal of the
North American Benthological Society 9:95–119.
Stubbington, R., A. J. Boulton, S. Little, and P. J. Wood. 2015.
Changes in invertebrate assemblage composition in benthic
and hyporheic zones during a severe supraseasonal drought.
Freshwater Science 34:XXX–XXX.
Taylor, G. I. 1954. The dispersion of matter in turbulent flow
through a pipe. Proceedings of the Royal Society of London, Series A: Mathematical and Physical Sciences 223(1155):446–
468.
Thackston, E. L., and K. B. Schnelle. 1970. Predicting the effects
of dead zones on stream mixing. Journal of the Sanitary Engineering Division, American Society of Civil Engineers 96:319–
331.
Triska, F. J., V. C. Kennedy, R. J. Avanzino, G. W. Zellweger, and
K. E. Bencala. 1989a. Retention and transport of nutrients in a
third-order stream in northwestern California: hyporheic processes. Ecology 70:1893–1905.
Triska, F. J., V. C. Kennedy, R. J. Avanzino, G. W. Zellweger, and
K. E. Bencala. 1989b. Retention versus transport of nutrients
in a third-order stream: channel processes. Ecology 70:1877–
1892.
Tristram, D. A., S. Krause, A. Levy, Z. P. Robinson, R. I. Waller, and J. J. Weatherill. 2015. Identifying spatial and temporal dynamics of proglacial groundwater–surface-water exchange
using combined temperature-tracing methods. Freshwater Science 34:XXX–XXX.
Vannote, R. L., G. W. Minshall, K. W. Cummins, J. R. Sedell, and
C. E. Cushing. 1980. The river continuum concept. Canadian
Journal of Fisheries and Aquatic Sciences 37:130–137.
Vazquez, E., E. Ejarque, I. Ylla, A. M. Romaní, and A.
Butturini. 2015. Impact of drying/rewetting cycles on the
bioavailability of dissolved organic matter molecular-weight
fractions in a Mediterranean stream. Freshwater Science 34:
XXX–XXX.
Vaux, W. G. 1962. Interchange of stream and intragravel water
in a salmon spawning riffle. US Department of the Interior,
US Fish and Wildlife Service, Washington, DC. Special Scientific Report—Fisheries No. 405:1–12.
Webster, J. R., P. J. Mulholland, J. L. Tank, H. M. Valett, W. K.
Dodds, B. J. Peterson, W. B. Bowden, C. N. Dahm, S. Findlay,
S. V. Gregory, N. B. Grimm, S. K. Hamilton, S. L. Johnson,
E. Martí, W. H. McDowell, J. L. Meyer, D. D. Morrall, S. A.
Thomas, and W. M. Wollheim. 2003. Factors affecting ammonium uptake in streams—an inter-biome perspective. Freshwater Biology 48:1329–1352.
*White, D. S. 1993. Perspectives on defining and delineating
hyporheic zones. Journal of the North American Benthological
Society 12:61–69.
Wondzell, S. M. 2011. The role of the hyporheic zone across
stream networks. Hydrological Processes 25:3525–3532.
Zarnetske, J. P., R. Haggerty, and S. M. Wondzell. 2015.
Coupling multiscale observations to evaluate hyporheic nitrate
removal at the reach scale. Freshwater Science 34:XXX–XXX.
Zimmer, M. A., and L. K. Lautz. 2015. Pre- and post-restoration
assessment of stream–groundwater interactions: impacts on
hydrological and chemical heterogeneity in the hyporheic zone.
Freshwater Science 34:XXX–XXX.
This content downloaded from 128.193.164.203 on Wed, 17 Dec 2014 14:07:34 PM
All use subject to JSTOR Terms and Conditions