Groundwater–surface-water interactions: current research directions

Abstract

The interfaces between rivers and aquifers are characterized by high spatial and temporal variation in water flow, heat exchange, biogeochemical activity, and microbial and metazoan communities. Scientific studies of these interfaces are collectively referred to as groundwater-surfacewater (GW-SW) interactions research. This nebulous term is appropriate, given the range of basic and applied issues that have been investigated in river-aquifer interfaces. These issues include contaminant remediation (Ren and Packman 2004), evolutionary change (Van Damme et al. 2009), rarespecies conservation (DiStefano et al. 2009), military history (Younger 2012), and the potential existence and nature of life on Mars (Gooseff et al. 2010). The papers in this special issue encompass a substantial part of that range, while omitting some of the extremes. Modern GW-SW science is an amalgamation of hydrogeology, biogeochemistry, landscape ecology, and other disciplines, many of which are themselves amalgamations of traditional science disciplines, such as microbiology and fluid mechanics (Robertson and Wood 2010, Krause et al. 2011). New branches of GW-SW science grow rapidly as the tools and perspectives of different disciplines are brought to bear on emerging research problems. Recent examples include nanobiotechnology (Sharma et al. 2012) and geomicrobiology (Gault et al. 2011). One consequence of the rapid diversification of GW-SW science is high research productivity. The publication rate in this field has grown exponentially for at least a decade (Wondzell 2015). GW-SW studies are often held up as models of multidisciplinary science (Danielopol and Griebler 2008, Krause et al. 2011).However, staying current with the state of knowledge in this prolific and expanding field is demanding.Our primary aim for this special issue was to intrigue and challenge readers who might otherwise focus on papers from within their own disciplines. We cast our net widely when inviting contributions to the issue, and we received papers about hydrological dynamics, biogeography, instrumentation, habitat restoration, and ecosystem services, among other topics. We recognize that some of these issues are outside of the usual scope of Freshwater Science, and that different issues are in the domains of different research communities, each with distinct concepts, tools, and terminology. In the spirit of life-long learning, we invite readers to read papers within and far outside of their specialties.We have grouped the 21 papers in this issue into 3 broad categories to provide some structure to the collection. The categories are hydrology and hydrodynamics, geochemistry and biogeochemistry, and ecology and biogeography. Within these categories, the papers report the results of field experiments, large-scale observational studies, and model development and testing. In each category, a synthesis paper provides a review of the state of knowledge and guidance for future research. The papers are summarized below. HYDROLOGY AND HYDRODYNAMICSA tenet of GW-SW scien...

Synthesizing models useful for ecohydrology and ecohydraulic approaches: An emphasis on integrating models to address complex research questions

“…Most regional analyses in our review were based on surface‐water models that lacked consideration of groundwater flow (Werner, Gallagher, & Weeks, ). This concurs with other studies that assert groundwater flows are poorly understood, but studies are increasingly focused in this area (Kalbus, Reinstrof, & Schirmer, ; Larned, Gooseff, Packman, Rugel, & Wondzell, ). Most groundwater‐centred integration models use MODFLOW (not formally reviewed in the current study, but commonly linked to SWAT; Chung et al, ; Kim, Chung, Won, & Arnold, ; Menking, Syed, Anderson, Shafike, & Arnold, ).…”

Unraveling complex hydrogeological processes in Andean basins in south‐central Chile: An integrated assessment to understand hydrological dissimilarity

“…In the same way, Langman and Ellis () found in the southern Rio Grande Valley in the southwestern USA that in a volcanic area with permeable layers and geological faults, deep groundwater interbasin connections would be allowed. Larned, Gooseff, Packman, Rugel, and Wondzell () stated that streams in tectonically active volcanic landscapes are characterized by complex groundwater‐surface water interactions that include interbasin transfers of groundwater. Similar to our study, the investigations described above attributed the interbasin water exchanges and basin dissimilarities in runoff to the volcanic deposits and geological (and relief‐related) formations.…”

Influence of Hydrological Perturbations and Riverbed Sediment Characteristics on Hyporheic Zone Respiration of CO2 and N2

“…As a zone that links the river and aquifer compartments, hyporheic zones represent a transitional region important for a multitude of ecosystem services (J. W. Harvey & Gooseff, ; Larned et al, ). Hyporheic zones support heterotrophic microbial aerobic respiration (AR), anaerobic denitrification (DN), and nitrification (NI) (Gomez‐Velez et al, ; J. W. Harvey et al, ), processes that transform a significant percentage of terrestrial organic matter (Casas‐Ruiz et al, ; Findlay, ; Rode et al, ).…”