Seepage Measurements Research Articles

Use of Seepage Meters to Measure Groundwater Flow at Brook Trout Redds

Abstract Anomalous influxes of water into unfilled collection bags can greatly overestimate volume and flow rate data from seepage meters. From static tank trials, initially empty collection bags (4,500 mL capacity) attached to seepage meters gained significantly more water relative to bags prefilled to 1,000 mL. Data from a study of groundwater flow at redds of brook trout Salvelinus fontinalis in Scott Lake, Ontario, indicate that the use of unfilled bags biases seepage meter data. At these redds, the anomalous influx of water into unfilled bags was significant (intercept of regression equation, y = 275 mL); however, this influx was sufficiently reduced when prefilled bags were used (v = 34 mL). Our data suggest that even at high flow rates (22–169 mL·m−2·min−1), seepage measures can be inflated by an order of magnitude when initially empty bags are used. Because of this anomaly, previous measures of groundwater flow at brook trout redds with unfilled bags are probably not representative of natural flow...

Application of 222Rn and CH4 for assessment of groundwater discharge to the coastal ocean

Groundwater discharge is a neglected source of freshwater and dissolved constituents to the ocean. It can occur via diffuse seepage and point source spring discharge. Two naturally occurring trace gases, 222Rn and CH4, are present in groundwater at concentrations that are elevated by several orders of magnitude relative to seawater, and they may be useful in tracing groundwater inputs to surface waters. Water samples collected near a submarine spring in the northeastern Gulf of Mexico displayed radon and methane concentrations inversely related to salinity and considerably greater than those found in surrounding waters. Coastal water 222Rn and CH4 inventories varied directly with groundwater seepage rates. The integrated quantities of 222Rn and CH4 in the nearshore waters overlying a seepage meter transect showed a significant positive relationship (95% C.L.) to direct measurements of seepage. Diffusive fluxes (178±56 dpm m‒2 d‒1), obtained by three different approaches at the same site, showed that these waters receive only a small contribution of 222Rn by diffusion. In contrast, benthic flux chamber measurements revealed a total advective‐diffusive contribution of 5,200±1,800 dpm m‒2 d‒1 (n = 14). Radon inventories in these shallow nearshore marine waters are consistent with the input of radon‐bearing groundwaters.

Seepage and antiseepage measures in foundations of hydraulic structures

1. Rock foundations of dams are inhomogeneous water-bearing systems, seepage in them has a complex and nonuniform character; for substantiating antiseepage measures the seepage model of foundations maximally corresponding to real conditions can be represented in the form of a three-dimensional piecewise-homogeneous model consisting of a number of structurally homogeneous fragments cut by systems of water-conducting fractures (zones) and confining interlayers. 2. The effective thickness of grout curtains on average is equal to 10–12 m, in zones of large-scale fracturing of the rocks — up to 20 m and more; the head gradients in the grout curtains do not exceed 10–18; the effectiveness of grout curtains depends substantially on the permeability of the surrounding rocks, and therefore the role which the grout curtain and drainage play under particular conditions is different. 3. The actual diagrams of uplift pressure in the foundations of many operating structures are below the design and standard ones. Under favorable hydrogeologic conditions a reduction of the heads by the watertight grout curtain and drainage in rock foundations of structures is not difficult and can be provided to values considerably less than the standard ones according to SNiP. A generalized diagram of the seepage heads is recommended for calculating the stability of dams on rock foundations in the presence of a grout curtain and drainage. 4. Watertight curtains made by the diaphragm wall method have a high effectiveness and economy. Their filler should be selected with consideration of the properties of the surrouding soils, SSS, and seepage strength of the foundation and diaphragm wall.

Seepage exchange in an Amazon floodplain lake

Exchange of water between the lake and the surrounding groundwater system was computed for a permanent lake on the central Amazon floodplain (Lake Calado) from an empirical seepage model incorporating 240 direct measurements of seepage from the lakebed and seasonal changes in lake stage and morphometry. Seepage rates varied with the daily rate of change in stage height and inversely with depth of the lakebed from the water surface. Since the hypsometric characteristics of the lake are well known, overall seepage for the 1983–1984 water year was estimated by integrating the product of seepage rate per unit area for a given rate of stage change and depth of lakebed with the representative area of lakebed at a given depth as each varied over the annual cycle, then integrating the daily rates of seepage over time. The volume of seepage outflow over the rising‐water period (4 × 106 m3) is plausible if the rate of groundwater flow is constrained by the hydraulic conductivities expected for the soils. The 10‐m annual change in water level and the potential movement of floodwaters into deeply weathered tropical soils, beyond the silt and clay deposits immediately adjacent to the main‐stem river channel, represent conditions that are particularly conducive to seepage exchange and are representative of a significant number of lakes on the Amazon floodplain.

Continuous measurements of ground-water seepage using an automatic seepage meter : Taniguchi, M; Fukuo, Y Ground WaterV31, N4, July-Aug 1993, P675–678

Continuous measurements of ground-water seepage using an automatic seepage meter : Taniguchi, M; Fukuo, Y Ground WaterV31, N4, July-Aug 1993, P675–678

Stochastic finite elements and experimental measurements

Basic concepts and methods of random field theory, needed to characterize “distributed disordered systems”, are reviewed, extended and applied. Linking stochastic finite element analysis to experimental measurements enables updating of response and performance predictions and optimizing data acquisition. The case studies involve analysis and measurement of seepage through randomly permeable strata below a dam and through the body of an earth dam.

Seepage and cutoff measures in the foundation of the Inguri arch dam

1. Systematic on-site observations of seepage were carried out during construction of the high-head arch dam of the Inguri hydrostation, from the results of which a refined model of permeability was drawn up, the effectiveness of the cutoff measures taken was assessed, and additional works were performed as necessary. 2. The seepage inflow into the drainage system and galleries of the underground contour was 400 liters/sec at a reservoir elevation of 410 m and about 1.9 m3/sec at the elevation of the NPL 510 m. This value changed little during each next filling of the reservoir to the NPL in 1989–1991 (1.95, 1.86, 1.83 m3/sec). 3. The grout curtain and drainage operate effectively and stably and reliably protect the bank abutments of the rock mass from water invasion. Some changes in the distribution of heads in the dam foundation are occurring in the plug part and its left-bank abutment at high levels and fluctuations of the reservoir as a result of decompression of the rocks and its change under the upstream face.

Analytical Descriptions of Subaqueous Groundwater Seepage

Direct measurements of groundwater seepage show the importance of subaqueous discharges as sources of fresh water and of dissolved chemicals to lakes and the coastal ocean. The rate of seepage decreases rapidly offshore; an analytical solution was developed that describes the discharge as Ki(In(coth πxk/4l))/k where i is the hydraulic gradient, K is the vertical hydraulic conductivity,l is the aquifer thickness, x is the distance from the shoreline, and k2 is K divided by the horizontal hydraulic conductivity. In addition to variations due to the inhomogeneities in the aquifer, seepage into the coastal ocean involves some recirculation of the salt water. In Great South Bay, New York measured fluxes were as great as 150 I m−2 d−1. The discharge near the shore was typically 50 I m−2 d−1, decreasing to 30 1 m−2 d−1 at a distance of 100 m offshore. Secondary convection due to an unstable density structure at the sediment-water interface may also be superimposed on the seepage distribution. Fingers of salt should be capable of carrying marine water many decimenters downward against the fresh groundwater advection. As a result, care must be exercised in interpreting direct measures of seepage flux to recognize the contribution of recirculated seawater.

和迩(わに)川デルタからの琵琶湖への地下水の漏出

Water levels of 39 wells and water qualities of samples from the wells have been measured to determine the groundwater movement in the Wani river delta, on the western shore of Lake Biwa. In the littoral zone around the delta, direct seepage measurements and sampling of seepage water and porewater have been carried out to clarify the seepage process of groundwater flow into Lake Biwa.Shallow groundwater is strongly recharged by effluent water from the Wani river an d moves into the lake in the direction perpendicular to the shore line. Slopes of water table near the shore range from 0.005∼0.01 at Wani beach and about 0.005 at Imajyuku beach throughout the year.Both seepage flux and electrical- conductivity of seepage water change spatially along the shore line. Areas along the transect perpendicular to the shore line show high values of seepage flux and electrical conductivity while near the shore, these values decrease abruptly with increasing distance from the shore. These patterns along the transect perpendicular to the shore line, however, do not show any significant spatial and seasonal changes throughout the study period. There are similar correlation between the quality of seepage waterwithin about 20m from the shore and that of well water near the shore. The distribution of chloride concentrations of groundwater in the vicinity of the lake indicates that the shallow groundwater (3∼5m depth below water table) in the aquifer discharges almost vertically into the lake within 20∼30m from the shore; the deeper water discharges into the lake at a distance of over 30m offshore.These results indicate that it is important to measure groundwater seepage at many sites near and along the shore line in order to estimate seepage amount into a lake and also suggest that the direct method employed is available to investigate shallow groundwater flow system near shore.

A comparison of two methodologies for assessment of irrigation performance under the Warabandi system

A water management study of Warabandi in northwest India in 1983 developed a methodology for assessing the performance of large scale smallholder irrigation schemes by observing irrigated areas and carrying out random crop cutting. A study of Warabandi in 1988 took a shorter amount of time and concentrated on direct measurements of flow and seepage in order to assess the performance of the physical conveyance system. This paper contrasts these two approaches and gives practical guidance on how to go about carrying out a rapid assessment of the performance of the physical conveyance system of an irrigation scheme.

Porewater acid/base chemistry in near-shore regions of an acidic lake

Sediment porewaters in the near-shore region (within 1 m of the shoreline) of an acidic lake (Dart's Lake) were monitored during the summer of 1983 to investigate whether spatial variations in porewater acid/base chemistry were significant in this region of the lake. Previous investigations of Dart's Lake porewaters have indicated that within deeper waters (>2m depth), sediment porewaters are elevated in alkalinity relative to overlying lake water. Within the near-shore region, porewaters both considerably more and less acidic than the lake water were observed. Both reduction of strong acid anions (SO42−, NO3−) and the mobilization of base cations were significant mechanisms of alkalinity production in porewaters exhibiting reducing conditions. In sediments reflecting oxic conditions, porewaters were generally more acidic than the lakewater. Measurement of groundwater seepage into the lake at the near-shore sites indicated that oxic sites exhibited elevated inputs of groundwater when compared to sites where reducing conditions existed. The acidic porewaters associated with high groundwater flows suggests that groundwater inputs to the lake may be a source of acidity (not alkalinity) on a whole-lake basis.

The spatially continuous determination of groundwater flow to surface water bodies: Application to the Connecting Channels between Lakes Huron and Erie

The hydrogeophysical method to define the hydraulic properties of the sediments beneath a surface water body described by Taylor and Cherkauer is applied to a specific field site. Collection of electrical resistivity and seismic data long over 200 km of survey lines in the channels connecting Lakes Huron and Erie has allowed definition of the thickness, general composition and hydraulic properties of the sediment column. The geophysics provided a measurement of electrical longitudinal conductance of the sediment column at 40-m intervals along the survey line (> 5000 complete electrical soundings). This parameter has been empirically related to the hydraulic leakance (ratio of the hydraulic conductivity to the thickness of the unconsolidated materials) of the sediment column at discrete calibration points where seepage meters were installed. Groundwater discharges calculated using the geophysically derived hydraulic properties compare very favorably with those calculated directly from the seepage measurements and others calculated independently from analysis of stream gaging records. Convergence of three methods on a single answer is taken to indicate the validity of that answer and to confirm the reliability of the hydrogeophysical approach. The hydrogeophysical approach offers the advantage of higher resolution of lateral variations in hydraulic properties and relatively low monetary and time expenditures when compared with a drilling program. However, it cannot be utilized without calibration to direct hydraulic measurements; it is best run in conjunction with seepage meters and drilling or existing wells. Perhaps its greatest usefulness lies in its ability to rapidly and accurately define locations of high potential for interaction between surface water and groundwater.

Field measurement and associated controlling factors for ground water seepage in a piedmont impoundment

AbstractKnowledge of groundwater seepage to and from lakes can be an important component of scientific investigations involving water and geochemical budgets. Measurements of groundwater seepage at Lake Anna, a man‐made lake in central Virginia, show that inflow to the lake occurs even under dry summer conditions. Seepage rates were found to be correlated with the elevation of the near‐shore water table, which responded rapidly to rainfall events in the fractured rock terrane in which Lake Anna is located. Seepage rates did not decline uniformly with distance offshore. This result contrasts with those for lakes underlain by relatively homogeneous porous media where measurements generally confirm the prediction that seepage rates drop off exponentially with distance from shore. The along shore variability of seepage rates in Lake Anna was related to a topographic index that is used to describe drainage from hillslopes. This suggests that seepage in impoundments such as Lake Anna may be strongly controlled by drainage pathways that pre‐date the lake.

Distribution of groundwater seepage to large surface-water bodies: The effect of hydraulic heterogeneities

At 26 sites on the upper Great Lakes and their connecting channels where groundwater seepage measurements have been made, seepages decrease continually offshore at only seven (26%). Instead, 17 (63%) of the sites have offshore seepages which substantially exceed those at some locations closer to shore. The distributions fall into two consistent patterns, one where a nearshore decrease in seepage with increasing distance is succeeded offshore by an increase and a second where nearshore seepages are relatively constant and then increase farther offshore. The patterns have been observed in two independent studies using two totally different seepage meter designs and emplacement methods and are attributed to hydrogeologic heterogeneities beneath the surface-water body. Detailed marine geophysical measurements at seven sites on Green Bay show that the anomalously high offshore seepages there are associated with local thinning of the relatively low hydraulic conductivity glacial sediments separating the Bay from the underlying aquifer, a fractured dolomite. At these locations, heterogeneity in sediment thickness is a stronger factor in causing seepage anomalies than is heterogeneity of either sediment or bedrock hydraulic conductivity. Insufficient information exists to confirm a parallel cause-effect relation at the other sites, but evidence points in that direction. Similar seepage anomalies have been observed at other, smaller lakes by other researchers, but never with this frequency. It is argued that the cause of the difference is the size of the Great Lakes. Seepage occurs and measurements have been made over much greater offshore distances than in smaller lakes, and the likelihood that heterogeneities will occur within the zone of measurement is thus also much greater.

湖沼と地下水 琵琶湖における調査・研究を中心として

The interrelation of groundwater and lake is perhaps the least understood aspect of lake hydrology. The net groundwater input to Lake Biwa had been estimated from hydrological budget and showed the figures of 1 billion tons per year or 15-20 % of total input (4.5 billion tons per year). As a result, the nutrient loading level due to groundwater component becomes a problem one should not ignore.The development of a simple device which permit direct measurement of groundwater seepage has made it possible to get an independent estimate of groundwater input, and to collect seepage water sample. The usefulness of this meter has been documented at many lakes especially in USA and Canada.The seepage meters were installed at 34 stations around the littral zone of Lake Biwa. Groundwater seepage rate at every station ranged from 3.5 to 460l/m2 · day, and total discharge was estimated to be 0.71 to 1.14 billion tons per year, which accounted for a substantial amount (16-26 %) of total input.The water qualilty of seepage meter sample was varied with sampling localities and times. At places, water samples very similar in composition to the lake water were found, but the almost samples were similar to the well water around the lake, except for nutrient elements. The nutrient concentrations of seepage water were considerably lower in nitrate nitrogen but higher in ammoniun nitrogen than the well water. The concentration of phosphate phosphorus was practically lower than the well water but slightly higher concentration accompanied by high alkalinity was observed at places where muddy sediments were prevailing.The seepage flux and seepage chemistry data can be combined to obtain an estimation of nutrient loading due to groundwater. The annual nitrogen and phosphorus loadings were estimated to be 270-580 tons and 41-77 tons respectively.

Use of seepage meters in a groundwater – lake interaction study in a fractured rock basin — a case study

Applications of seepage meters in lakes with slight bottom sediments in fractured rock basins have not been reported. A study of the hydrogeology of Long Lake, at Halifax, Nova Scotia, used seepage meters in this situation. Fifteen meters were installed in the 1.7 km2 lake — seven in a line extending from the shore, the remaining eight on the lake periphery. Seepage measurements were made monthly over 1 year. Groundwater levels were measured in boreholes in the fractured granite of the watershed. A positive inflow of groundwater to the lake occurred through the year, seepage flux at the shoreline meters varied from 0.15 to 0.78 mL∙m−2∙s−1, with no consistent seasonal variations. Seepage decreased exponentially with offshore distance. A linear relationship was evident between water levels in a borehole near the shore and rate of seepage at the closest meter. Chloride applied to this borehole was reflected in elevated chloride concentrations in seepage collected by the meter. Key words: seepage meter, groundwater – lake system, fractured rock tracers.

Foundation Treatment in Karstic Limestone: El Cajon Hydroelectric Project, Honduras

The El Cajon Project, completed in 1985, provides the necessary hydroelectric energy to relieve Honduras of the need for importing oil for generating purposes. The existing interconnection with Nicaragua and Costa Rica allows Honduras to export electricity on demand using the new facility. Steps are being taken to construct transmission lines to both Guatemala and El Salvador and thereby develop a regional electric inter-tie system. Construction began in 1980 following nine years of effort that included a final feasibility study, field investigations, design, and procurement of the necessary financing. One of the major aspects of the project was the treatment of the limestone foundation that contained solution features and large caves. Because of the geologic relationship between the limestone and nearby volcanic rocks upstream, the geometry of the grout curtain is unique. The curtain, developed by grouting between adjacent galleries, begins at the dam, enters the abutments and then curves upstream to close against the volcanic rocks. The curtain is therefore vertical in the abutments with a transition to a nearly horizontal plane beneath the river. The overall shape is similar to a bathtub with the back of the tub open to the reservoir. A comprehensive monitoring program was initiated when impoundment began in 1985 and will continue for several years. Measurements of seepage, pressures, and displacements are made regularly with periodic review by outside consultants. At the time of this writing, the reservoir is 80 percent full and the performance of the foundation is considered to be satisfactory.

Field Analysis of Seepage from Drainwater Evaporation Ponds

ABSTRACT Anine month field study was conducted on a 36.6 ha evaporation pond used for disposal of subsurface drain water to evaluate different methods for measurement of seepage in the field from aqueous impoundments. Estimates of pond seepage rates were based on water balance calculations, and the geometric means of pre-construction data from laboratory analyses and data from two different layouts of infiltrometers within the pond. Spatial variability of infiltrometer point measurements of seepage rates was found to be lognormally distributed. Spatial distribution structure of seepage rates in the pond remained constant throughout the study period. Results indicate that infiltrometer based estimates of pond seepage compare favorably, but are subject to less variability, than seepage rates estimated from water balance calculations. The effort required for infiltrometer measurements in the field, however, is much greater than that required for mass balance calculations.

Seepage control at Cochiti Dam, New Mexico : Lillard, D E In: Seepage and Leakage from Dams and Impoundments (paper to the symposium, Denver, Colorado, 5 May 1985) P82–114. Publ New York: ASCE, 1985

Significant design data, design assumptions and computations, and performance of the seepage control features provided at Cochiti Dam are summarized in this paper. The dam is a rolled and zoned earthfill embankment. Evaluations of in situ permeabilities of the granular foundation materials were complicated by variations in thickness of overburden above bedrock, the complex and irregular stratifications of granular foundation materials, and the major thicknesses of foundation overburden above existing ground water table. Based on the results of field and laboratory tests, a design permeability curve as related to D//2//0 soil size was developed for seepage analyses. Based on seepage measurements during storage of the 1979 record pool, the measured foundation seepage quantities are less than the quantities of seepage estimated in design.

Use of a Numerical Ground‐Water Flow Model for Hypothesis Testing

ABSTRACTField studies along the southeastern shore of Trout Lake, Wisconsin, documented the presence of downward hydraulic gradients in a known discharge area as well as an anomalous distribution of seepage to the lakebed which deviates significantly from the generally accepted dogma that ground‐water seepage rates decrease exponentially with distance from shore. A numerical ground‐water model facilitated identification of the hydrologic control, namely the presence of a unit of high hydraulic conductivity, that accounts for the anomalous data, and is important for understanding the dynamics of the flow system. Field data including seepage measurements, visual inspection of lakebed materials and springs, and information obtained during drilling, indicate that a lens of coarse‐grained material intersects the lake. However, the significance of the coarsegrained material was not fully appreciated until a ground‐water model was used to simulate the flow system. The model indicated that the presence of the coarse‐grained lens has a marked effect on the flow pattern in the nearshore area causing downward hydraulic gradients which divert ground water into the lens and cause the occurrence of a localized high‐seepage area offshore where the lens intersects the lake. The numerical model predicts the anomalous seepage distribution noted in the field and the downward hydraulic gradients demonstrating that numerical models are practical tools for interpreting field data and for use in hypothesis testing.