Framework

Seepage Measurement Methods

Most methods of assessing surface water-groundwater interactions are indirect. This means that the nature and magnitude of seepage flux is inferred or calculated from the measurements of other parameters such as hydraulic head, hydraulic conductivity, temperature or isotopes. Direct methods use instruments that directly measure the flow of water at the interface between the surface water feature and the aquifer.

Seepage Meters

Seepage meters are the most commonly used devices for the direct measurement of seepage flux. These were initially developed in the 1940s to measure loss of water from irrigation channels (Israelson and Reeve, 1944) and resurrected in the 1970s for use in small lakes and estuaries (McBride and Pfannkuch, 1975; Lee, 1977; John and Lock, 1977; Lee and Cherry, 1978). Seepage meters have since been used in numerous studies of seepage fluxes in rivers (Lee and Hynes, 1978; Libelo and MacIntyre, 1994; Cey et al, 1998; Landon et al, 2001), the near-shore marine zone (Bokuniewicz and Pavlik, 1990; Valiela et al, 1990; Cable et al, 1997; Taniguchi et al, 2003), tidal zones (Belanger and Walker, 1990; Robinson et al, 1998), coral reefs (Simmons and Love, 1984, Lewis, 1987), large lakes (Cherkauer and McBride, 1988) and water-supply reservoirs (Woessner and Sullivan, 1984). A constant-head variant of the seepage meter (the Idaho meter) has been used to measure leakage from irrigation channels into aquifers under Australian conditions (ANCID 2000; Byrnes and Webster, 1981).

The basic concept of the seepage meter is to cover and isolate part of the sediment-water interface with a chamber open at the base and measure the change in the volume of water contained in a bag attached to the chamber over a measured time interval. The classic design of Lee (1977) consists of a 15-cm end section of a 55-gallon (~200L) drum, which is inserted into the sediment. A stopper with a tube is inserted into a hole in the top of the drum and a plastic bag is attached to the tube with rubber bands. The time when the bag is connected and when it is subsequently disconnected is recorded, as well as the change in the volume of water in the bag.

The seepage flux (Q) is calculated as:

Q=(Vf-V0)/tA

Equation A1.1

where Vo is the initial volume of water in the bag, Vf is the final volume of water in the bag, t is the time elapsed between when the bag was connected and disconnected, and A is the surface area of the chamber. Additional water in the bag represents upwards (gaining) seepage and water loss from the bag represents downward (losing) seepage. In environments with positive seepage flux, the water in the bag can be collected for chemical analysis.

Seepage Meter Design

Seepage Meter Operation

Automated Seepage Meters

Advantages

  1. Is the only commonly available direct measurement of seepage flux. As it is a direct measurement, seepage meters have the potential to validate indirect methods that involve measuring secondary indicators such as hydraulic head difference, chemical tracers or isotopes. However, this can only be undertaken when there is confidence that any potential measurement errors have been recognised and minimised.
  2. Is based on a simple concept and are inexpensive to construct, using readily available components. They can be easily incorporated into field investigations as they can be installed at the beginning of the trip, regularly monitored and then removed at the end of the trip.
  3. Useful for defining relative differences in seepage flux, particularly for mapping seepage hotspots.
  4. Can be used as a valuable educational tool, to raise awareness of the connectivity between groundwater and surface water resources.

Disadvantages

  1. Only effectively measures seepage flux at a point in space. Many measurements are required to derive meaningful interpolations, which is labour-intensive and time consuming.
  2. Tend to have poor repeatability due to high spatial and temporal variability in seepage characteristics. Such variability can be attributed to variations in water levels through time, spatial variations in aquifer hydraulic conductivity, the presence of a thin clogging layer and changes in its hydraulic resistance, or variable seepage velocities across the stream profile, with velocity decreasing with increasing distance from the bank (Kaleris, 1998).
  3. In low-flux environments (such as in heavy clay sediments or where hydraulic gradients are low) measurements may require days for an adequate change in bag water volume to derive a reliable estimate.
  4. Manual seepage meters only measure the aggregate seepage over a measured time period, and do not provide any data on how seepage changes during that time period.
  5. Significant measurement errors can be introduced with the design and operation of the seepage meter. Processes such as upward advection of interstitial water caused by the chamber having a positive relief in a flowing stream (the Bernoulli effect), venturi effects of stream flow on the collection bag, hydraulic resistance along the internal boundaries of the meter causing head losses, or accumulation of sediment gas in the chamber can lead to misleading data. This means that measurements from seepage meters are generally not reliable enough to quantify seepage flux in absolute terms.
  6. The fluxes measured may not be entirely groundwater, but include other sources such as shallow throughflow or recirculation of surface water through the sediments. This can be a major issue if the seepage meter is not installed to a sufficient depth into the sediment.
  7. Generally unsuitable for installation on hard, gravely or weedy sediment beds because of the difficulty in providing an effective seal and installation depth. Sand, silt or soft clay are the best sediment material for bedding down the chamber. Also difficult to install in deep or fast-flowing water, being more suited to less dynamic environments such as drains, shallow lakes or lagoons.

Data Availability

Seepage meter measurements of surface water features are not routinely undertaken in Australia. The most common use of seepage meters is in the measurement of water losses from irrigation supply channels. A list of rural water suppliers (which potentially have undertaken such investigations) is maintained by ANCID.

Case Studies

Lower Richmond seepage meter trials

Relevant Links

ANCID Channel Seepage Management Tool

References

ANCID, 2000. Open channel seepage and control. Vol 1.1 Literature review of channel seepage identification and measurement. Australian National Committee on Irrigation and Drainage. Prepared by Sinclair Knight Merz.

Belanger TV, Walker RB, 1990. Ground water seepage in the Indian River Lagoon, Florida. In: Tropical Hydrology and Caribbean Water Resources: Proceedings of the International Symposium on Tropical Hydrology and Fourth Caribbean Islands Water Resources Congress. American Water Resources Association. 367-375.

Bokunieicz H, Pavlik B, 1990. Groundwater seepage along a barrier island. Biogeochemistry 10:437-444.

Byrnes RP, Webster A, 1981. Direct measurement of seepage from earthen channels. Technical Paper No 64. Australian Water Resources Council, Canberra.

Cable JE, Burnett WC, Chanton JP, Corbett DR, Cable PH, 1997. Field evaluation of seepage meters in the coastal marine environment. Estuarine, Coastal and Shelf Science 45:367-375.

Cey EE, Rudolph DL, Parkin GW, Aravena R, 1998. Quantifying groundwater discharge to a small perennial stream in southern Ontario, Canada. Journal of Hydrology 210:21-37.

Cherkauer DS, McBride JM, 1998. A remotely operated seepage meter for use in large lakes and rivers. Ground Water 26:165-171.

Israelson OW, Reeve RC, 1944. Canal lining experiments in the Delta Area, Utah. Utah Agricultural Experimental Station, Bulletin 313: 15-35.

John PH, Lock MA, 1977. The spatial distribution of groundwater discharge into the littoral zone of a New Zealand lake. Journal of Hydrology 33: 391-395.

Kaleris V, 1998. Quantifying the exchange rate between groundwater and small streams. Journal of Hydraulic Research 36(6): 913-932.

Landon MK, Rus DL, Harvey FE, 2001. Comparison of instream methods for measuring hydraulic conductivity in sandy streambeds. Ground Water 39:870-885.

Lee DR, 1977. A device for measuring seepage flux in lakes and estuaries. Limnology and Oceanography 22(1):140-147.

Lee DR, Cherry JA, 1978. A field exercise on groundwater flow using seepage meters and mini-piezometers. Journal of Geological Education 27:6-10.

Lee DR, Hynes HBN, 1978. Identification of groundwater discharge zones in a reach of Hillman Creek in southern Ontario. Water Pollution Research Canada 13:121-133.

Lewis JB, 1987. Measurements of groundwater seepage-flux into a coral reef: Spatial and temporal variation. Limnology and Oceanography 32:1165-1169.

Libelo EL, McIntyre WG, 1994. Effects of surface-water movement on seepage meter measurements of flow through the sediment-water interface. Hydrogeology Journal 2:49-54.

McBride MS, Pfannkuch HO, 1975. The distribution of seepage within lakebeds. Journal of Research, US Geological Survey, 3(5):505-512.

Robinson M, Gallagher D, Reay W, 1998. Field observations of tidal and seasonal variations in ground water discharge to tidal estuarine surface water. Ground Water Monitoring and Remediation 18(1):83-92

Simmons Jr GM, Love FG, 1986. Water quality of newly discovered submarine ground water discharge into a deep coral reef habitat. Final Report to Sanctuary Program Division, Office of Ocean and Coastal Resource Management. National Oceanic and Atmospheric Administration, Washington.

Taniguchi M, Burnett WC, Smith CR, Paulsen RJ, O'Rourke D, Krupa SL, Christoff JL, 2003. Spatial and temporal distributions of submarine discharge rates obtained from various types of seepage meters at a site in the Northeastern Gulf of Mexico. Biogeochemistry 66:35-53.

Valiela I, Costa J, Foreman K, Teal JM, Howes B, Aubrey D, 1990. Transport of groundwater-borne nutrients from watersheds and their effects on coastal waters. Biogeochemistry 10:177-197

Woessner WW, Sullivan KE, 1984. Results of seepage meter and mini-piezometer study, Lake Mead, Nevada. Ground Water 22(5): 561-568.