History and evolution of seepage meters for quantifying flow between groundwater and surface water: Part 1 – Freshwater settings (original) (raw)
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An Automated Seepage Meter for Streams and Lakes
Water Resources Research, 2020
We describe a new automatic seepage meter for use in soft bottom streams and lakes. The meter utilizes a thin-walled tube that is inserted into the streambed or lakebed. A hole in the side of the tube is fitted with an electric valve. Prior to the test, the valve is open and the water level inside the tube is the same as the water level outside the tube. The test starts with closure of the valve, and the water level inside the tube changes as it moves toward the equilibrium hydraulic head that exists at the bottom of the tube. The time rate of change of the water level immediately after the valve closes is a direct measure of the seepage rate (q). The meter utilizes a precision linear actuator and a conductance circuit to sense the water level to a precision of about ±0.1 mm. The meter can also provide an estimate of vertical hydraulic conductivity (K v) if data are collected for a characteristic time. The detection limit for q depends on the vertical hydraulic head gradient. For K v = 1 m/day, q of about 2 mm/day can be measured. Results from a laboratory sand tank show excellent agreement between measured and true q, and results from a field site are similar to values from calculations based on independent measurements of K v and vertical head gradients. The meter can provide rapid (30 min) q measurements for both gaining and losing systems and complements other methods for quantifying surface water groundwater interactions.
Field Evaluation of Seepage Meters in the Coastal Marine Environment
Estuarine Coastal and Shelf Science, 1997
The response of seepage meters was evaluated in a nearshore marine environment where water motion effects are more pronounced than in lake settings, where these meters have been used traditionally. Temporal and spatial variations of seepage, as well as potential artifacts, were evaluated using empty and 1000-ml pre-filled bag measurements. Time-series measurements confirmed earlier observations that anomalously high fluxes occur during the early stages (c10 min) of collection. As deployment times increased (30-60 min), measured flow rates stabilized at a level thought to represent the actual seepage flux. Pre-filling the plastic measurement bags effectively alleviated this anomalous, short-term influx. Reliable seepage measurements required deployment times sufficient to allow a net volume of at least 150 ml into the collection bag. Control experiments, designed by placing seepage meters inside sand-filled plastic swimming pools, served as indicators of external effects on these measurements, i.e. they served as seepage meter blanks. When winds were under 15 knots, little evidence was found that water motion caused artifacts in the seepage measurements. Tidal cycle influences on seepage rates were negligible in the present study area, but long-term temporal variations (weeks to months) proved substantial. Observed long-term changes in groundwater flux into the Gulf of Mexico correlated with water table elevation at a nearby monitoring well.
Use of Seepage Meters to Measure Groundwater Flow at Brook Trout Redds
Transactions of the American Fisheries Society, 1996
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 Salvelinusfontinalis 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 (y = 34 mL). Our data suggest that even at high flow rates (22-169 mL-irr 2-min '), 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 rates. Our estimates of groundwater flow at brook (rout redds in Scott Lake (6-296 mL-nrr 2-min~!) are very similar to the range in groundwater flow found in lake and stream redds (4-340 mL-m'-min' 1) by other methods. We suggest the use of prefilled collection bags (filled to 1,000 mL) and conformity in measurement units (mL-m~2-min~') when groundwaler flow is measured with seepage meters.
Measuring methods for groundwater, surface water and their interactions: a review
Hydrology and Earth System Sciences Discussions, 2006
Interactions between groundwater and surface water play a critical role in the functioning of riparian ecosystems. In the context of sustainable river basin management it is crucial to understand and quantify exchange processes between groundwater and surface water. Numerous well-known methods exist for parameter estimation and process 5 identification in aquifers and surface waters. The transition zone, however, has only in recent years become a subject of major research interest, and the need has evolved for appropriate methods applicable in this zone. This article provides an overview of the methods that are typically used in aquifers and surface waters when studying interactions and shows the possibilities of application in the transition zone. In addition, 10 methods particularly for use in the transition zone are presented. Considerations for choosing appropriate methods are given including spatial and temporal scales, uncertainties, and limitations in application. It is concluded that a multi-scale approach combining multiple measuring methods may considerably constrain estimates of fluxes between groundwater and surface water. 15 25 ever, due to infiltration of stream water into the pore space, the zone may contain 1810 Abstract Introduction Conclusions References Tables Figures Back Close Full Screen / Esc Printer-friendly Version Interactive Discussion
Limnology and Oceanography: Methods, 2006
Seepage meters, like most benthic flux chamber techniques, come with inherent concerns about how their presence may alter the environment and flow regimen of the benthic boundary layer and underlying sediments. Flow due to wave and current movement across topographic features induces a downward and upward flow field within the sediments surrounding the feature. We found this Bernoulli-induced flow is a real, but maybe minor, component of measured advection using seepage meters. This study was conducted in a Florida coastal lagoon to test the physical forcing mechanisms that may influence seepage measurements from sediments. Calculated Bernoulli seepage was within the measured background (~1 to 2 cm day-1) expected from seepage meters when a plastic barrier beneath the device is used to inhibit natural seepage contributions. Nearby seepage measurements made with Lee-type seepage meters placed directly in the sediments ranged from 1 to 12 cm day-1. Thus, when seepage flow is very slow from sediments, Bernoulli-induced seepage may obscure the measurement. However, this study demonstrates that seepage in the Indian River Lagoon must be driven by forces other than Bernoulli-induced (pumped) flow. Suggestions for these forcing mechanisms highlight the uncertainty of the water source(s) in seepage measurements. In these Florida lagoon sediments, bioirrigation and terrestrial groundwater inputs are the most likely drivers, depending on distance from shore, benthic community composition, and continental recharge. Seepage measurements can be an excellent measure of advection in shallow-water marine sediments if Bernoulli-induced seepage is taken into account either experimentally or calculated based on local hydrographic and meteorological data.