The Effect of streambed topography on surface‐subsurface water exchange in mountain catchments

Abstract

A numerical hydrological simulation suggested that water exchange between stream channels and adjacent aquifers is enhanced by convexities and concavities in streambed topography. At St. Kevin Gulch, an effluent stream in the Rocky Mountains of Colorado, subsurface hydraulic gradients and movement of ionic tracers indicated that stream water was locally recharged into well‐defined flow paths through the alluvium. Stream water‐filled flow paths in the alluvium (referred to as substream flow paths) returned to the stream a short distance downstream (1 to 10 m). Recharge to the substream flow paths occurred where stream water slope increased, at the transition from pools (<1%) to steeper channel units (5–20%). Return of substream flow paths to the stream occurred where stream water slope decreased, at the transition from steeper channel units to pools. A net water flux calculation is typically used to characterize water and solute fluxes between surface and subsurface zones of catchments. Along our study reach at St. Kevin Gulch the net inflow of water from subsurface to stream (1.6 mL s−1 m−1) underestimated the gross inflow (2.7 mL s−1 m−1) by 40%. The influence of streambed topography is to enhance hydrological fluxes between stream water and subsurface zones and to prolong water‐sediment contact times; these effects could have important consequences for solute transport, retention, and transformation in catchments.

Environmental Hydrology

“…[42] Results at transect 3 oppose the conceptual model of compressed hyporheic zones under strong gaining conditions that has been reported in both numerical [e.g., Boano et al, 2008;Cardenas and Wilson, 2007b;D'Angelo et al, 1993] and field studies [e.g., Harvey and Bencala, 1993;Storey et al, 2003;Williams, 1993;Wondzell and Swanson, 1996;Wroblicky et al, 1998]. While increasingly strong hydraulic gradients away from the stream may expand hyporheic zones (or conversely, increasing hydraulic gradients toward the stream compress hyporheic zones), our results do not indicate hyporheic expansion with Figure 9.…”

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

“…These systems should therefore exhibit heavy-tailed residence time distributions and breakthrough curves. Moreover, as rivers generally have fractal topography [Turcotte, 1997], and surface-groundwater exchange is induced by all scales of topography, not just flow-bedform interaction [Harvey and Bencala, 1993], our findings may apply to other types of streams. Characterization of riverbed morphology along with hyporheic exchange and local vertical velocities and head gradients is therefore expected to enable new and more general assessment of surface-subsurface exchange processes.…”

“…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].…”

Groundwater and Surface Water Interaction at the Regional-scale – A Review with Focus on Regional Integrated Models

“…The characteristics of the regional scaled catchments are determined by a range of possible combinations of climate, geomorphology, geology, landscape types, and biological factors that can occur in parallel within the same study area (Dahl et al 2007;Harvey and Bencala 1993;Larkin and Sharp 1992;Sophocleous 2002;Winter 1999). Any enlargement of the study area size will increase the variety of combinations of these factors and thus lead to an increase in complexity.…”