Physical controls and predictability of stream hyporheic flow evaluated with a multiscale model

Abstract

[1] Improved predictions of hyporheic exchange based on easily measured physical variables are needed to improve assessment of solute transport and reaction processes in watersheds. Here we compare physically based model predictions for an Indiana stream with stream tracer results interpreted using the Transient Storage Model (TSM). We parameterized the physically based, Multiscale Model (MSM) of stream-groundwater interactions with measured stream planform and discharge, stream velocity, streambed hydraulic conductivity and porosity, and topography of the streambed at distinct spatial scales (i.e., ripple, bar, and reach scales). We predicted hyporheic exchange fluxes and hyporheic residence times using the MSM. A Continuous Time Random Walk (CTRW) model was used to convert the MSM output into predictions of in stream solute transport, which we compared with field observations and TSM parameters obtained by fitting solute transport data. MSM simulations indicated that surface-subsurface exchange through smaller topographic features such as ripples was much faster than exchange through larger topographic features such as bars. However, hyporheic exchange varies nonlinearly with groundwater discharge owing to interactions between flows induced at different topographic scales. MSM simulations showed that groundwater discharge significantly decreased both the volume of water entering the subsurface and the time it spent in the subsurface. The MSM also characterized longer timescales of exchange than were observed by the tracerinjection approach. The tracer data, and corresponding TSM fits, were limited by tracer measurement sensitivity and uncertainty in estimates of background tracer concentrations. Our results indicate that rates and patterns of hyporheic exchange are strongly influenced by a continuum of surface-subsurface hydrologic interactions over a wide range of spatial and temporal scales rather than discrete processes.

Fractal patterns in riverbed morphology produce fractal scaling of water storage times

“…Since rivers have fractal topography and interactions between river flow and boundary topography drive hyporheic exchange [Harvey and Bencala, 1993;Stonedahl et al, 2010;Tonina and Buffington, 2011;Kiel and Cardenas, 2014;Gomez-Velez and Harvey, 2014], the ubiquitous fractal properties of rivers should produce fractal patterns in hyporheic flow paths and fractal scaling in the associated residence time distributions [Worman et al, 2007;Stonedahl et al, 2012]. Other mechanisms that can produce broad travel time distributions include subsurface heterogeneity and nested flow paths in homogeneous systems [Kirchner et al, 2001;Scher et al, 2002;Cardenas, 2007].…”

“…The exchange of water between surface and subsurface flows, generally termed hyporheic exchange, plays a critical role in structuring fluvial ecosystems [Boulton et al, 1998;Aubeneau et al, 2015]. Several studies have shown that fractal topography can produce scaling in hyporheic residence time distributions [Stonedahl et al, 2012[Stonedahl et al, , 2013Gomez-Velez and Harvey, 2014]. Worman et al [2006Worman et al [ , 2007 used numerical experiments to demonstrate the link between fractal topography and water storage times.…”

“…Travel times in rivers and watersheds are very broadly distributed [Kirchner et al, 2000;Haggerty et al, 2002;Stonedahl et al, 2012;Aubeneau et al, 2014], but the mechanisms that produce travel time distributions over many orders of magnitude are not known precisely [Boano et al, 2014]. The exchange of water between surface and subsurface flows, generally termed hyporheic exchange, plays a critical role in structuring fluvial ecosystems [Boulton et al, 1998;Aubeneau et al, 2015].…”

Designing and Evaluating the Quality and Cost-effectiveness of Saturated Sediment Permeameters

“…Many studies (Stonedahl et al, 2010;Stonedahl et al, 2012;Marion et al, 2008;Salehin et al, 2004, Elliot andBrooks, 1997b;Sawyer, 2009;Buffington & Tonina, 2009) require hydraulic conductivity values. Our research group found methods to measure the K-value that were expensive (Humboldt 2016B;Gilson;2016, Eijkelkamp, 2016 and methods, which we could not reproduce with precision or accuracy (Conners, 2012).…”

Scaling down hyporheic exchange flows: from catchments to reaches

“…In the 25 next sections we discuss how temporal and spatial variations in groundwater and river levels influence the extent of the HZ and HEF. Within the context of groundwater dynamics, we accept that HEF takes place in both losing and gaining stream conditions (Harvey and Bencala, 1993;Harvey et al, 2003;Stonedahl et al, 2012;Fox et al, 2014) although the way it occurs is a function of regional groundwater and catchment characteristics interacting with smaller-scale reach properties (Larkin and Sharp, 1992;Wondzell and Gooseff, 2013).…”