Relative influences of the river channel, floodplain surface, and alluvial aquifer on simulated hydrologic residence time in a montane river floodplain

Helton, Ashley M.; Poole, Geoffrey C.; Payn, R. A.; Izurieta, Clemente; Stanford, Jack A.

doi:10.1016/j.geomorph.2012.01.004

Cited by 70 publications

(90 citation statements)

References 31 publications

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“…The annual flow regime of the fifth‐order river is dominated by snowmelt, with a mean discharge of 80 m 3 s −1 and mean peak discharge of 600 m 3 s −1 (discounting the extraordinary peak discharge of nearly 4000 m 3 s −1 that occurred in 1964) [ Poole et al , 2004]. Annual spring floods inundate large areas of the non‐channel floodplain surface [ Helton et al , 2012].…”

Section: Study Sitementioning

confidence: 99%

Scaling flow path processes to fluvial landscapes: An integrated field and model assessment of temperature and dissolved oxygen dynamics in a river‐floodplain‐aquifer system

Helton¹,

Poole²,

Payn³

et al. 2012

J. Geophys. Res.

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[1] Biogeochemical cycling within river ecosystems is strongly influenced by geomorphic and hydrologic dynamics. To scale point observations of temperature and dissolved oxygen (DO) to a hydrologically complex and dynamic three-dimensional river-floodplain-aquifer system, we integrated empirical models of temperature and biotic oxygen utilization with a recently published hydrogeomorphic model. The hydrogeomorphic model simulates channel flow, floodplain inundation, and surface-subsurface water exchange on the 16 km 2 Nyack Floodplain, Middle Fork Flathead River, Montana, USA. Model results were compared to observed data sets of DO to test the hypothesis that complexity in spatiotemporal patterns of biogeochemistry emerges from a comparatively simple representation of biogeochemical processes operating within a multidimensional hydrologic system. The model explained 58% of the variance in 820 DO measurements that spanned the study site longitudinally, laterally, vertically, and across river discharge conditions and seasons. We also used model results to illustrate spatial and temporal trends of temperature and DO dynamics within the shallow alluvial aquifer, which is an extensive hyporheic zone because subsurface alluvial flow paths are recharged primarily by channel water. Our results underscore the importance of geomorphic, hydrologic, and temperature dynamics in driving river ecosystem processes, and they demonstrate how a realistic representation of a river's physical template, combined with simple biogeochemical models, can explain complex patterns of solute availability.

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Section: Study Sitementioning

confidence: 99%

Scaling flow path processes to fluvial landscapes: An integrated field and model assessment of temperature and dissolved oxygen dynamics in a river‐floodplain‐aquifer system

Helton¹,

Poole²,

Payn³

et al. 2012

J. Geophys. Res.

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“…The aquifer is characterized by extreme hydraulic conductance up to 11.6 cm s −1 (ref. 9) and is exclusively recharged by the river6. It is therefore considered a voluminous ‘hyporheic' zone where surface and ground waters interchange (Supplementary Fig.…”

mentioning

confidence: 99%

“…2). Water residence times vary from hours to three years in relation to lengths of flow paths from the river through the aquifer9. Overall, the aquifer is well oxygenated because oxygen diffuses from the vadose zone of the floodplain10.…”

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confidence: 99%

Ancient and methane-derived carbon subsidizes contemporary food webs

DelVecchia

Stanford

2016

Nat Commun

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While most global productivity is driven by modern photosynthesis, river ecosystems are supplied by locally fixed and imported carbon that spans a range of ages. Alluvial aquifers of gravel-bedded river floodplains present a conundrum: despite no possibility for photosynthesis in groundwater and extreme paucity of labile organic carbon, they support diverse and abundant large-bodied consumers (stoneflies, Insecta: Plecoptera). Here we show that up to a majority of the biomass carbon composition of these top consumers in four floodplain aquifers of Montana and Washington is methane-derived. The methane carbon ranges in age from modern to up to >50,000 years old and is mostly derived from biogenic sources, although a thermogenic contribution could not be excluded. We document one of the most expansive ecosystems to contain site-wide macroinvertebrate biomass comprised of methane-derived carbon and thereby advance contemporary understanding of basal resources supporting riverine productivity.

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“…During overbank floods, surface water velocities decrease in floodplains relative to the channel, resulting in increased potential for reactions, such as net production or removal of nutrients (Bukaveckas, ; Kronvang et al ., ; Harrison et al ., ). Floodplain topography dictates surface water storage and mixing on the floodplain (Mertes, ) and floodplain soil properties affect surface water and groundwater flow and exchange across the floodplain surface (Krause and Bronstert, ; Doble et al ., ; Helton et al ., ).…”

Section: Introductionmentioning

confidence: 99%

Vertical surface water–groundwater exchange processes within a headwater floodplain induced by experimental floods

Hester¹,

Guth²,

Scott

et al. 2016

Hydrological Processes

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Restoring hydrologic connectivity between channels and floodplains is common practice in stream and river restoration. Floodplain hydrology and hydrogeology impact stream hydraulics, ecology, biogeochemical processing, and pollutant removal, yet rigorous field evaluations of surface water–groundwater exchange within floodplains during overbank floods are rare. We conducted five sets of experimental floods to mimic floodplain reconnection by pumping stream water onto an existing floodplain swale. Floods were conducted throughout the year to capture seasonal variation and each involved two replicate floods on successive days to test the effect of varying antecedent moisture. Water levels and specific conductance were measured in surface water, soil, and groundwater within the floodplain, along with surface flow into and out of the floodplain. Vegetation density varied seasonally and controlled the volume of surface water storage on the floodplain. By contrast, antecedent moisture conditions controlled storage of water in floodplain soils, with drier antecedent moisture conditions leading to increased subsurface storage and slower flood wave propagation across the floodplain surface. The site experienced spatial heterogeneity in vertical connectivity between surface water and groundwater across the floodplain surface, where propagation of hydrostatic pressure, preferential flow, and bulk Darcy flow were all mechanisms that may have occurred during the five floods. Vertical connectivity also increased with time, suggesting higher frequency of floodplain inundation may increase surface water–groundwater exchange across the floodplain surface. Understanding the variability of floodplain impacts on water quality noted in the literature likely requires better accounting for seasonal variations in floodplain vegetation and antecedent moisture as well as heterogeneous exchange flow mechanisms. Copyright © 2016 John Wiley & Sons, Ltd.

show abstract

Relative influences of the river channel, floodplain surface, and alluvial aquifer on simulated hydrologic residence time in a montane river floodplain

Cited by 70 publications

References 31 publications

Scaling flow path processes to fluvial landscapes: An integrated field and model assessment of temperature and dissolved oxygen dynamics in a river‐floodplain‐aquifer system

Scaling flow path processes to fluvial landscapes: An integrated field and model assessment of temperature and dissolved oxygen dynamics in a river‐floodplain‐aquifer system

Ancient and methane-derived carbon subsidizes contemporary food webs

Vertical surface water–groundwater exchange processes within a headwater floodplain induced by experimental floods

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