River‐Aquifer Interactions, Geologic Heterogeneity, and Low‐Flow Management

Abstract

Low river flows are commonly controlled by river-aquifer exchange, the magnitude of which is governed by hydraulic properties of both aquifer and aquitard materials beneath the river. Low flows are often important ecologically. Numerical simulations were used to assess how textural heterogeneity of an alluvial system influences river seepage and low flows. The Cosumnes River in California was used as a test case. Declining fall flows in the Cosumnes River have threatened Chinook salmon runs. A ground water-surface water model for the lower river basin was developed, which incorporates detailed geostatistical simulations of aquifer heterogeneity. Six different realizations of heterogeneity and a homogenous model were run for a 3-year period. Net annual seepage from the river was found to be similar among the models. However, spatial distribution of seepage along the channel, water table configuration and the level of local connection, and disconnection between the river and aquifer showed strong variations among the different heterogeneous models. Most importantly, the heterogeneous models suggest that river seepage losses can be reduced by local reconnections, even when the regional water table remains well below the riverbed. The percentage of river channel responsible for 50% of total river seepage ranged from 10% to 26% in the heterogeneous models as opposed to 23% in the homogeneous model. Differences in seepage between the models resulted in up to 13 d difference in the number of days the river was open for salmon migration during the critical fall months in one given year.

Investigating patterns and controls of groundwater up-welling in a lowland river by combining Fibre-optic Distributed Temperature Sensing with observations of vertical hydraulic gradients

“…The potential for hyporheic and riparian nutrient attenuation in lowland rivers has been shown to be substantial (Krause et al, 2008a, b;Pinay et al, 2009;Zarnetske et al, 2011b). However, as result of the depositional history of the river system, exchange flow between groundwater and surface water can be spatially highly heterogeneous, causing complex flow patterns at the aquifer-river interface (Fleckenstein et al, 2006;Lowry et al, 2007;Rosenberry and Pitlick, 2009). Uncertainty in the detection of exchange flow patterns increases with increasing spatial scale (White, 1993;Kasahara and Wondzel, 2003;Krause et al, 2009aKrause et al, , 2011a, with crucial implications for the (un)certainty of predictions of HZ biogeochemical and ecohydrological functioning (Brunke and Gonser, 1997;Boulton et al, 1998;Krause et al, 2011c).…”

“…At the larger (up to several kilometre) stream reach to sub-catchment scale, exchange fluxes between groundwater and surface water can be strongly affected by larger geological heterogeneities in the alluvial aquifer and the resulting groundwater flow field (Cardenas and Wilson, 2006;Fleckenstein et al, 2006;Engdahl et al, 2010;Frei et al, 2009). At smaller, plot to stream reach scales, however, exchange fluxes over the aquifer-river interface appear to be strongly controlled by spatial patterns of streambed hydraulic conductivity (Genereux et al, 2008;Leek et al, 2009;Calver, 2001;Rosenberry, 2008;Käser et al, 2009) and streambed topography (Storey et al, 2003;Boano et al, 2006Boano et al, , 2010Cardenas, 2009;Cardenas et al, 2008;Kasahara and Hill, 2008;Tonina and Buffington, 2007).…”

Nutrient dynamics, transfer and retention along the aquatic continuum from land to ocean: towards integration of ecological and biogeochemical models

“…The interaction between groundwater and surface water is heterogeneous at various scales, where interaction in the floodplain, riparian and hyporheic zone also plays a role (e.g., Fleckenstein et al, 2006;Sear et al, 1999). It will be impossible to model this complexity in detail at the basin scale.…”

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

“…Many such models seem to exist (e.g. Feyen 2005) but not all of them have necessarily been published in peer-reviewed literature. They are often developed by national -Zhangye basin, China, 9,097 km 2 (Tian et al, 2015) (Wilcox et al, 2007) MODCOU / EauDyssée Saleh et al (2011) Pryet et al (2014) ?…”