Effect of surficial disturbance on exchange between groundwater and surface water in nearshore margins

Abstract

[1] Low-permeability sediments situated at or near the sediment-water interface can influence seepage in nearshore margins, particularly where wave energy or currents are minimal. Seepage meters were used to quantify flow across the sediment-water interface at two lakes where flow was from surface water to groundwater. Disturbance of the sediment bed substantially increased seepage through the sandy sediments of both lakes. Seepage increased by factors of 2.6 to 7.7 following bed disturbance at seven of eight measurement locations at Mirror Lake, New Hampshire, where the sediment representing the greatest restriction to flow was situated at the sediment-water interface. Although the veneer of low-permeability sediment was very thin and easily disturbed, accumulation on the bed surface was aided by a physical setting that minimized wind-generated waves and current. At Lake Belle Taine, Minnesota, where pre-disturbance downward seepage was smaller than at Mirror Lake, but hydraulic gradients were very large, disturbance of a 20 to 30 cm thick medium sand layer resulted in increases in seepage of 2 to 3 orders of magnitude. Exceptionally large seepage rates, some exceeding 25,000 cm/d, were recorded following bed disturbance. Since it is common practice to walk on the bed while installing or making seepage measurements, disruption of natural seepage rates may be a common occurrence in nearshore seepage studies. Disturbance of the bed should be avoided or minimized when utilizing seepage meters in shallow, nearshore settings, particularly where waves or currents are infrequent or minimal.Citation: Rosenberry, D. O., L. Toran, and J. E. Nyquist (2010), Effect of surficial disturbance on exchange between groundwater and surface water in nearshore margins, Water Resour. Res., 46, W06518,

Hydrogeological controls on spatial patterns of groundwater discharge in peatlands

“…Preferentially stronger flow paths are thus concentrated at the break in land surface slope (Blume et al, 2013;Casson et al, 2010;Cherkauer and McKereghan, 1991;McBride and Pfannkuch, 1975;Rosenberry et al, 2010;Winter, 1981). Previous work proposes that seepage flux decreases exponentially with distance from the shore of a lake (Cherkauer and Zager, 1989;McBride and Pfannkuch, 1975), which is qualitatively confirmed by our data.…”

“…5), consistent with margin seepage observed in lake environments (Rosenberry et al, 2010;Sebestyen and Schneider, 2004;Sebok et al, 2013;Winter, 2001) and other wetlands (Freeze, 1988;Labaugh et al, 1998). The peat is 0.1-3.0 m thick along the margin where matrix seepage occurs (Fig.…”

“…PFP seeps develop as fast pathways to the surface and as pressure-relief valves, where these localized increases in aquifer pressure at the base of the peat matrix translate into strong, sustained discharge of unaltered regional groundwater to the surface. Rosenberry et al (2010) note that in lake bottoms, a significant upward seepage velocity can maintain a locally high K, as the upward force may suspend smaller particles within the water column. Particulate organic matter and lacustrine sediment have a very low settling velocity, and therefore if the upward force that groundwater seepage induces is greater than the settling velocity, only organic matter with a high mass will be able to accumulate over these lake seepage locations.…”

Role of a groundwater–lake interface in controlling seepage of water and nitrate

“…Not much work has been carried out on the influence of the lake bed itself on discharge despite that this part of the interface likely is hydraulically different from the underlying aquifer unit. Rosenberry et al (2010) discuss some of the mechanisms responsible for surface colmation (clogging of the sediment-water interface) and straining (infiltration of finer materials to pore spaces of coarse material below the sedimentwater interface) and conducted seepage measurements at two lakes trying to look into the effects of disturbing the upper sediments of a lake bed on seepage from the lake to groundwater (i.e. recharge).…”

Nutrient Dynamics at the Interface Between Surface Water and Groundwater With Aquatic Vegetation: An Experimental Approach

“…High concentrations of N may exacerbate eutrophication (Rosenberry et al, 2010) and cause changes in species composition (Ommen et al, 2012), eventually leading to a notable decrease in macrophyte biomass and species richness in shallowlakes (Kidmose et al, 2013).…”