Mapping increases in hyporheic exchange from channel-spanning logjams

Doughty, M.; Sawyer, Audrey H.; Wohl, Ellen; Singha, Kamini

doi:10.1016/j.jhydrol.2020.124931

Cited by 34 publications

(51 citation statements)

References 55 publications

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“…Skew calculated from bulk electrical conductivity is much less Figure S2; Doughty et al, 2020). We estimate skewness from both our instream and bulk conductivity data-we call these instream and bulk skew moving forward.…”

Section: Methodsmentioning

confidence: 89%

“…These discharges represent nearly bankfull flow, approximately half bankfull and base flow. Three tracer tests were conducted on the same days at segments 1 and 2 during summer 2018 (Doughty et al, 2020), and three on the same days at segments 3 and 4 during summer 2019. Tracer was injected into the centre of the creek, tens of metres upstream to allow complete mixing above the stream segments and for 4 h during each test.…”

Section: Methodsmentioning

confidence: 99%

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Logjams as a driver of transient storage in a mountain stream

Ader

Wohl

McFadden

et al. 2021

Earth Surf Processes Landf

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We use four stream segments along a wood-rich, pool-riffle mountain stream in the Southern Rockies of Colorado, USA to examine how spatial variations in wood load and variations in discharge during and after the snowmelt peak flow influence the magnitude of surface and subsurface transient storage. Segments range in complexity from a single channel with no large wood to an anabranching channel with closely spaced, channel-spanning logjams. Discharges at which transient storage was assessed range from base flow to snowmelt peak flow. To explore these relations, we used 10 geomorphic variables representing channel morphology and bed substrate, four wood-related variables representing wood load and associated backwater storage, and two measures of skewness from instream and bulk electrical conductivity breakthrough curves during tracer tests. Instream curves reflect surface and subsurface transient storage, whereas bulk curves primarily represent subsurface transient storage. Higher values of skewness indicate greater retention, and we used the values here as a metric of increased transient storage. Although limited sample size restricts the power of our results, our findings suggest that stream segments with greater instream large wood loads have more and larger pools, greater storage of fine sediment and particulate organic matter, and higher values of skew from instream conductivity. The results also suggest that the presence of instream wood, rather than changes in channel morphology associated with wood, is the most important driver of transient storage. This implies that river management designed to foster transient storage should focus on retaining instream large wood. We did not find significant correlations between geomorphic or wood-related variables and the skew estimated from bulk conductivity, which may reflect the relatively thin alluvium present in the field area and the prevalence of surface transient storage in this system.

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Section: Methodsmentioning

confidence: 89%

Section: Methodsmentioning

confidence: 99%

Logjams as a driver of transient storage in a mountain stream

Ader

Wohl

McFadden

et al. 2021

Earth Surf Processes Landf

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“…Previous work indicates that unconfined, low gradient reaches, which have been referred to as “beads” along the string of a river's length (Stanford et al, 1996), are also disproportionately important with respect to denitrification (Wegener et al, 2017; Wohl, Lininger, et al, 2018), organic carbon storage (Sutfin & Wohl, 2019; Wohl et al, 2012), and biomass and biodiversity (Bellmore & Baxter, 2014; Herdrich et al, 2018; Venarsky et al, 2018). Because channel‐spanning logjams can induce formation of secondary channels (Collins et al, 2012; Wohl, 2011), beads with logjams also exhibit more spatially heterogeneous river corridors and greater channel‐floodplain and channel‐hyporheic (Doughty et al, 2020; Sawyer et al, 2011) hydrologic connectivity. The resilience of the longitudinal distribution of logjams and associated changes in river corridor form and function suggest that introducing wood or engineered logjams to beads in small to moderate rivers can create persistent benefits in river corridors.…”

Section: Discussionmentioning

confidence: 99%

“…Consequently, logjams influence hydraulics (Dudley et al, 1998; Gippel, 1995; Manners et al, 2007) and transport or retention of mineral sediment and particulate organic matter (Beckman & Wohl, 2014a; Bilby, 1981; Livers & Wohl, 2016; Wohl & Scott, 2017). By obstructing flow and creating pressure gradients, logjams enhance hyporheic exchange flows (Doughty et al, 2020; Hester & Doyle, 2008; Lautz et al, 2006). Logjams also influence channel cross‐sectional and planform geometry (Collins et al, 2012; Curran & Wohl, 2003; Wohl, 2011) and aquatic habitat and biomass (Herdrich et al, 2018; Richmond & Fausch, 1995; Venarsky et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

The resilience of logjams to floods

Wohl

Scamardo

2020

Hydrological Processes

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Logjams that span the bankfull channel strongly influence hydraulics and downstream fluxes of diverse materials. Several studies quantify the longitudinal distribution of channel‐spanning logjams, but fewer studies examine changes in longitudinal distribution in response to disturbances such as floods. We use 10 years of annual surveys of a population of channel‐spanning logjams along mountain streams in the Southern Rocky Mountains. Surveys from 2010 to 2019 bracket substantial interannual variability in the snowmelt peak flow as well as a rainfall flood in 2013. We characterised the number of logjams per unit length of valley (logjam distribution density) within and between reaches designated based on longitudinally consistent channel and valley geometry. Our primary objectives are to evaluate the influences on logjam distribution density of (i) spatial variations in valley and channel geometry and (ii) temporal variations in peak annual flow. We hypothesized that logjam distribution densities are resilient to disturbance at both spatial scales. At the creek scale, logjam distribution density correlates significantly with increasing ratio of floodplain width to channel width and wood piece length to channel width. Wide, low gradient reaches with greater distribution density exhibit greater interannual variation in distribution density. These reaches lost jams during the 2013 flood but returned to pre‐flood distribution density values by the end of the study. The pattern of greater logjam distribution density in unconfined reaches relative to confined and partially confined reaches is also consistent over the period of the study. We interpret these results as indicating the resilience of logjam distributions to disturbance. The persistence of greater numbers of logjams in wide, low gradient reaches suggests that river restoration employing engineered logjams and wood reintroduction can focus most effectively on these reaches.

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“…Creek, where draining mine adits had been successfully blocked (Butler, 2019). In terms of natural restoration, areas with topographic features, such as beaver dams, along Cement Creek could potentially have higher hyporheic exchange potential (Doughty et al 2020). Beavers also disturb the streambed that they work in, potentially breaking up the subsurface layers of ferricrete.…”

Section: Discussionmentioning

confidence: 99%

Analysis of the Influence of Ferricrete on Hyporheic Exchange Flows

Rickel¹

2020

Geological Society of America Abstracts With Programs

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The area of confluence between surface water and groundwater, known as the hyporheic zone, is a natural biogeochemical filter that is dependent on channel morphology and hydraulic conductivity, pressure-driven downwelling and upwelling currents, and stream discharge. In Cement Creek near Silverton, Colorado, deposition of amorphous iron minerals reduces the permeability of the streambed and limits flow through the hyporheic zone. This limited exchange may lower the potential for pollutant attenuation from the metals-loaded waters of Cement Creek within the hyporheic zone. This study found that hyporheic exchange in this system is limited in spatial extent and reduces during low flow when compared to what we would expect from streams without ferricrete. To quantify flow through the hyporheic zone, we used time-lapse electrical resistivity of the streambed and banks of Cement Creek taken over the course of a day in conjunction with a four-hour salt injection tracer test. The solute was constrained within the streambed, with little flow through the banks, and had longer residence times in the hyporheic zone during high flow than at low flow. Slug test data suggested the presence of a zone of lower permeability at 44-cm depth that was likely made of precipitated ferricrete that cemented cobbles together. The comparison of apparent bulk conductivity from the geophysics to in-stream fluid conductivity allowed for the calculation of mass transfer parameters between the stream and hyporheic zone based on the difference in solute retardation patterns in the two breakthrough curves. During high flow, in-stream breakthrough curves displayed slower breakthrough and greater smoothing which is consistent with the geophysical inversion results that indicate higher residence times at high flow. Analyses of low flow data indicated decreased residence time within the subsurface and comparatively faster breakthrough. The hyporheic storage area within Cement Creek, estimated from the modeled capacity coefficient, decreased by two orders of magnitude between high (0.5 m 2 as modeled from hysteresis curve and in STAMMT-L) and low flow (0.

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Mapping increases in hyporheic exchange from channel-spanning logjams

Cited by 34 publications

References 55 publications

Logjams as a driver of transient storage in a mountain stream

Logjams as a driver of transient storage in a mountain stream

The resilience of logjams to floods

Analysis of the Influence of Ferricrete on Hyporheic Exchange Flows

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