Spatial Distribution of Seepage at a Flow‐Through Lake: Lake Hampen, Western Denmark

Abstract

The spa al distribu on of seepage at a fl ow-through lake in western Denmark was invesgated at mul ple scales with integrated use of a seepage meter, lake-groundwater gradients, stable isotope frac ona on (δ 18 O), chlorofl uorocarbon (CFC) apparent ages, land-based and off -shore geophysical surveys, and lake bed coring. Results were compared with a three-dimensional catchment-scale groundwater fl ow model using the MODFLOW and LAK3 codes for simula ng lake-groundwater interac on. Seepage meter and model results of discharging groundwater to the lake compared well, if direct seepage measurements from near shore were combined with measurements from deeper parts of the lake. Discharge rates up to 9.1 × 10 −7 m s −1 were found. Ground-penetra ng radar used to map the lake bed sediments proved very eff ec ve in recognizing low-and high-permeability areas but also in understanding the complex recharge pa ern of the lake and rela ng these to the geologic history of the lake. Recharge of the surrounding aquifer by lake water occurs off shore in a narrow zone, as measured from lake-groundwater gradients. A 33-m-deep δ 18 O profi le at the recharge side shows a lake δ 18 O plume at depths that corroborates the interpreta on of lake water recharging off shore and moving down gradient. Inclusion of lake bed heterogeneity in the model improved the comparison of simulated and observed discharge to the lake. The apparent age of the discharging groundwater to the lake was determined by CFCs, resul ng in ages between 3 and 36 yr with an average of 16 yr. The simulated average groundwater age was 13.2 yr.Abbrevia ons: CFC, chlorofl uorocarbon; GPR, ground-penetra ng radar; MEP, mul electrode profi le; MLW, mul level well.Groundwater-dominated lakes are especially vulnerable to deterioration in lake water quality due to inputs from polluted groundwater. An understanding of the distribution and rate of seepage to and from lakes is therefore needed for environmental management or restoration of lake ecosystems (Hayashi and Rosenberry, 2002;Sophocleous, 2002;Gleeson et al., 2009). Several studies have demonstrated the infl uence of seepage on (i) lake water quality, e.g., the discharge of nutrient-rich groundwater (Loeb and Goldman, 1979;Brock et al., 1982;Belanger et al., 1985;Ito et al., 2007), groundwater rich in cations (Dean et al., 2003;Cullmann et al., 2006), dissolved inorganic and organic C (Striegl and Michmerhuizen, 1998;Staehr et al., 2010), or, in general, changes in lake alkalinity as a result of weathering processes in the watershed (Schafran and Driscoll, 1993); or (ii) biological communities, e.g., biodiversity and species distribution in seepage zones (Lodge et al., 1989;Hagerthey and Kerfoot, 1998;Rosenberry et al., 2000;Hayashi and Rosenberry, 2002;Sebestyen and Schneider, 2004).Th e exchange of water and solutes between groundwater and lakes is complex and there is still a challenge in understanding the temporal and spatial variability across diff erent scales (Käser et al., 2009). To address this challenge, a ...

Upscaling lacustrine groundwater discharge rates by fiber-optic distributed temperature sensing

“…Spatial variability in drivers (hydraulic head gradients) and controls (hydraulic conductivity) of exchange fluxes determine patterns of lacustrine groundwater discharge (LGD). Significant spatial heterogeneity of seepage fluxes has been revealed by a number of experimental studies [e.g., Kishel and Gerla, 2002;Kidmose et al, 2011;Cherkauer and Nader, 1989;Lautz and Ribaudo, 2012]. For example, Kishel and Gerla [2002] identified significant horizontal and vertical heterogeneity of flow directions and fluxes within a densely spaced grid of piezometers (every 2 m in a 10 3 10 m domain).…”

Interactions of artificial lakes with groundwater applying an integrated MODFLOW solution

“…1). The Turawa lakebed leakance was indeed low (0.0007-0.0015 day −1 ) as compared to leakances of natural lake studies, which were one to two (0.059-0.077 day −1 in Virdi et al 2013) or even two to three (0.26 day −1 in Kidmose et al 2011) orders of magnitude larger.…”

“…The importance of the peripheral seepage zone in the lakegroundwater interaction was emphasized, MODFLOWmodelled and field-validated by Kidmose et al (2011) at the natural Lake Hampen (0.760 km 2 surface area, 3.2 Mm 3 volume and rainfall~900 mm year −1 ) in western Denmark. In their steady-state model, shoreline seepage was highly spatially variable, ranging from L LKout =~−70 mm day −1 to L LKin =~60 mm day −1 and was in agreement with seepage meter measurements.…”

“…In the LAK3 Package, also, the simulation of solute transport was added. The LAK3 Package was validated through seepage meter measurements by Kidmose et al (2011) and applied in a number of studies such as, for example, in Vaeret et al (2009). Another important improvement took place recently in the most up-to-date LAK7 Package, also used in this study.…”

Simulating the Effects of Lake Wind Waves on Water and Solute Exchange across the Lakeshore Using Hydrus-2D

“…Interactions between lake and groundwater systems have become major concerns during recent decades [2][3][4][5], since they may exert an important control on lake ecology [6,7] and on the nearshore water quality [8] in multiple ways. An understanding of the distribution and rate of seepage to and from lakes is therefore needed for environmental management and the restoration of lake ecosystems [8][9][10].…”