Measuring Groundwater–Stream Water Exchange: New Techniques for Installing Minipiezometers and Estimating Hydraulic Conductivity

Abstract

Measurements of groundwater–stream water interactions are increasingly recognized as important to understanding the ecology of fishes and other organisms in stream and riparian ecosystems. However, standard measurement techniques are often feasible only at small spatial scales, in areas with easy access, or in systems with relatively fine substrata. We developed simple new techniques for installing minipiezometers and obtaining estimates of vertical hydraulic gradient, hydraulic conductivity, and specific discharge in gravel and cobble streambeds that allowed for large numbers of measurements to be obtained in remote locations. Our approach yielded values comparable to those obtained through more traditional methods. Consequently, these techniques may provide a labor cost‐efficient way for detecting groundwater−stream water interaction patterns that are critical labor‐attributes of stream and riparian systems at multiple scales.

Measuring methods for groundwater – surface water interactions: a review

“…Assuming vertical flow beneath the streambed, the hydraulic gradient is obtained from the difference of the water level in the piezometer and the stream, and the depth from the sediment surface to the centre of the piezometer screen (Freeze and Cherry, 1979). Baxter et al (2003) described an installation technique for minipiezometers which permits obtaining a large number of measurements in gravel and cobble streambeds.…”

Coarse particulate organic matter in the interstitial zone of three French headwater streams

“…A length of plastic tubing (Tygon, 5 mm inner diameter) was hermetically sealed at the top of each cylinder to allow sampling of interstitial water, and kept isolated from surface water with a clamp. Two cylinders were carefully introduced in the sediment of each of three representative riffles per stream, by using a piezometer pushed to 20 cm depth into streambed using an internal metallic rod, as described in Baxter et al (2003). The middle of each cylinder was approximately 15 cm below the streambed surface.…”

Spawning site selection and the influence of incubation environment on larval success in interior Fraser coho.

“…Permeability is a function of just the porous medium, whereas hydraulic conductivity is a function of both the porous medium and the fluid that is being transmitted (Freeze and Cherry, 1979;Sanders 1998). A falling-head slug test (Freeze and Cherry, 1979;Sanders, 1998;Baxter et al, 2003) was used to measure hydraulic conductivity at each study site. A known volume of water was added to the minipiezometer and the rate at which the water level returned to its initial level in the minipiezometer was timed.…”

“…The slug test was conducted by adding 10ml of stream water to the mini-piezometer and measuring the rate of change in water level. An estimate of hydraulic conductivity (Kh) (cm/second) was calculated using an equation derived by Baxter et al, (2003) that was designed to be used specifically when measurement of time lag is not practical. The equation is:…”

“…Lastly, measurements of vertical hydraulic gradient and hydraulic conductivity were used to calculate specific discharge (v) at each study site using the equation (Baxter et al, 2003):…”