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Guelph Permeameter Abstracts
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Adderly, W.P. and Simpson, I.A. 2006, 'Soils and Palaeo-climate based Evidence for Irrigation Requirements in Norse Greenland', Journal of Archaeological Science, vol. 33, pp. 1666-1679.
Establishing and sustaining agricultural production was a key factor in the success of Norse settlements during the landnám colonisation across the North Atlantic. In light of the occurrence of channel features in several abandoned home-field areas of the Norse Eastern Settlement of Greenland, and the irrigation requirements of present-day Greenlandic sheep-farmers questions are raised: was irrigation used by the Norse settlers of Greenland on their home-field areas? and, if so, how frequently? Modelling of soil chemical, physical and soil-water hydraulic properties integrated with contemporary high-resolution climatic data demonstrate a frequent requirement for irrigation. Soil moisture deficits are related to the duration and intensity of winter temperature. Using the winter Dye 3 ice core δ18O record as a climatic proxy, the frequency of moisture deficits, based on comparing mean winter temperatures, indicates that there was a frequent irrigation requirement to maintain home-field productivity, increasing throughout the period of settlement until the 14th Century.
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American Society for Testing and Materials 1990, 'Standard Guide for Comparison of Field Methods for Determining Hydraulic Conductivity in the Vadose Zone. Designation: D 5126 – 90 (Reapproved 1998)', American Society for Testing and Materials, Philadelphia, PA.
1.1 This guide provides a review of the test methods for determining hydraulic conductivity in unsaturated soils and sediments. Test methods for determining both field-saturated and unsaturated hydraulic conductivity are described.
1.2 Measurement of hydraulic conductivity in the field is used for estimating the rate of water movement through clay liners to determine if they are a barrier to water flux, for characterizing water movement below waste disposal sites to predict contaminant movement, and to measure infiltration and drainage in soils and sediment for a variety of applications. Test methods are needed for measuring hydraulic conductivity ranging from 1 x 10-2 to 1 x 10-8 cm/s, for both surface and subsurface layers, and for both field-saturated and unsaturated flow.
1.3 For these field test methods a distinction must be made between “saturated” (Ks) and “field-saturated” (Kfs) hydraulic conductivity. True saturated conditions seldom occur in the vadose zone except where impermeable layers result in the presence of perched water tables. During infiltration events or in the event of a leak from a lined pond, a “field-saturated” condition develops. True saturation does not occur due to entrapped air. The entrapped air prevents water from moving in air-filled pores that, in turn, may reduce the hydraulic conductivity measured in the field by as much as a factor of two compared to conditions when trapped air is not present. Field test methods should simulate the “field-saturated” condition.
1.4 Field test methods commonly used to determine fieldsaturated hydraulic conductivity include various double-ring infiltrometer test methods, air-entry permeameter test methods, and borehole permeameter tests. Many empirical test methods are used for calculating hydraulic conductivity from data obtained with each test method. A general description of each test method, and special characteristics affecting applicability is provided.
1.5 Field test methods used to determine unsaturated hydraulic conductivity in the field include direct measurement techniques and various estimation methods. Direct measurement techniques for determining unsaturated hydraulic conductivity include the instantaneous profile (IP) test method, and the gypsum crust method. Estimation techniques have been developed using borehole permeameter data, and using data obtained from desorption curves (a curve relating water content to matric potential).
1.6 The values stated in SI units are to be regarded as standard.
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Australian Standards, 1999, Method 6.7.3: Soil Strength and Consolidation Tests—Determination of Permeability of a Soil—Constant Head Method using a Flexible Wall Permeameter. AS 1289.6.7.3-1999 SAI Global.
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Azooz, R.H., Arshad, M.A., et al. 1996, 'Pore Size Distribution and Hydraulic Conductivity Affected by Tillage in Northwestern Canada', Soil Science Society of America Journal, vol. 60, no. 4, pp. 1197-1201.
Tillage management can affect crop growth, in part by altering the pore structure and hydraulic properties of soil. We hypothesized that water retention, pore size distribution, and unsaturated hydraulic conductivity (k) differed under conventional tillage (CT) and no tillage (NT). We evaluated this hypothesis on a Donnelly silt loam (fine-loamy, mixed, frigid Typic Cryoboralf) and a Donnelly sandy loam (coarseloamy, mixed, frigid Typic Cryoboralf) in northwestern Canada. Soil cores were collected from the 0- to 300-mm depth in 75-mm increments. Water retention was measured at 10 pressure levels from -2 to -400 kPa to calculate pore size distribution and k. Both soils retained 0.04 to 0.09 m3 m–3 more water under NT than under CT. The volume fraction of total porosity with pores <7.5 µm in diameter (effective pores for retaining plant-available water) in the silt loam averaged 0.49 and 0.58 m3 m–3 under CT and NT, respectively, and in the sandy loam averaged 0.39 and 0.51 m3 m–3 under CT and NT, respectively. In contrast, the volume fraction of total porosity with pores >150 µm in diameter (pores draining freely with gravity) in the silt loam averaged 0.29 and 0.23 m3 m–3 under CT and NT, respectively, and in the sandy loam averaged 0.35 and 0.24 m3 m–3 under CT and NT, respectively. Conventional tillage appeared more likely to interrupt capillaries than NT, since large differences in k between tillage regimes were observed below a depth of 75 mm with increasing moisture deficit. Continuous NT management increased water storage of both silt loam and sandy loam soils in this cold, semiarid region.
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Bagarello, V. and Iovino, M. 2003, 'Field Testing Parameter Sensitivity of the Two-term Infiltration Equation using Differentiated Linearization', Vadose Zone Journal, vol. 2, pp. 358-367.
Knowledge of the hydraulic conductivity of the vadose zone is important in many agronomic, engineering and environmental areas. Transient tension infiltrometer experiments can be used to estimate the hydraulic conductivity, K0, corresponding to a given pressure head by a transient single-test (TST) method that uses the coefficients C1 and C2 of the two-term infiltration equation. A differentialized linearization (DL) method was previously proposed to estimate these coefficients when a layer of contact material is used for the experiment. A field test of the DL and TST methods was conducted on a sandy loam and a clay soil. Eliminating the early-time influence of the contact layer was easy when the sorptivity of the contact material was 10 to 12 times higher than the soil sorptivity. In other cases a transition zone, which complicated application of the DL method, appeared between the decreasing and increasing portions of the data set. Therefore, applicability of the DL method required large differences in capillary forces between the contact material and the soil. Estimates of K0 varied by up to 650% with the duration of the experiment and <50% with the time interval between readings at the water reservoir. Sensitivity of K0 to the experiment duration was particularly remarkable for the sandy loam soil for soil durations. Considereing a minimum duration of the experiment of approximately 1 h caused estimates of K0 to vary by a maximum of 40% with the duration of the experiment.
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Giakoumakis, S.G. and Tsakiris, G.P. 1999, 'Quick Estimation of Hydraulic Conductivity in Unsaturated Sandy Loam Soil', Irrigation and Drainage Systems, vol. 13, pp. 349-359.
Laboratory experiments were conducted for determining hydraulic conductivity during infiltration in an unsaturated sandy loam soil, using both steady state and equilibrium methods. A constant head Guelph permeameter and a volumetric pressure plate extractor were used. Based on two ponded heights in the permeameter, the parameters of Gardner's equation expressing the unsaturated hydraulic conductivity as a function of pressure head (i.e. the saturated hydraulic conductivity Ks and the exponent α), were estimated simultaneously. Furthermore, it was found that the parameter α, could also be predicted from the soil-water retention curve based on equilibrium data obtained from the extractor. This indicated that, for the soil type studied, one-ponded height in the permeameter method could be sufficient for the determination of the exponent α, provided that the soil-water retention curve is known.
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Mikulec, V. 2005, 'Impact of Saturated Hydraulic Conductivity of Soils on Numerical Simulation of Soil Water Movement', in Monitoring and Modelling the Properties of Soil as a Porous Medium, eds. W.M. Skierucha and R.T. Walczak, Institute of Agrophysics PAS, Lublin, pp. 86-94
Saturated hydraulic conductivity is the most sensitive input into the physically based numerical models of soil water movement. In presented study was evaluated the impact of saturated hydraulic conductivity, measured by laboratory method of the Falling Head permeameter and field methods of Disc and Guelph permeameter, on mathematical simulation of soil water movement. Values of hydraulic conductivity were measured during growing season of vegetation in 1999 at locality Royal Meadow (Kralovska Luka). Three sets of the hydraulic conductivity values were obtained. Separately for each set of measured values, an average value of hydraulic conductivity for every determined material horizon of studied soil profile was calculated. Owing to these three sets of input values, three variants of simulation of soil water movement, for given locality and time period, were performed. From the results of realized variants of numerical simulation, the water content values in soil horizons 0 - 30, 31 - 60 and 61 - 90 cm were calculated. These values were compared in correspondent horizons. There are also presented values of the water content, obtained from measured values of soil moisture at studied locality during given time interval, in this study. Comparison shows a very good correlation between the values of water content calculated from measured and from modeled values of soil moisture.
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Murray, C.J., Ward, A.L., et al. 2007, 'Influence of Clastic Dikes on Vertical Migration of Contaminants at the Hanford Site', Vadose Zone Journal, vol. 6, pp. 959-970.
Clastic dikes are subvertical sedimentary features that cut through horizontally layered sediments, and they are common at the Hanford Site. Because of their cross-cutting relationship with the surrounding matrix, they have been proposed as potential fast paths from former contaminant discharge sites at the surface to the water table. However, little was known of the detailed hydrogeologic properties of the dikes, and detailed modeling of flow and transport through the dikes had not been performed. We excavated a 2-m-wide clastic dike at the Hanford Site and characterized it using an air minipermeameter, infrared imagery, and grain size analyses. Field injection experiments were also used to characterize the system. The resulting data were used to prepare a detailed numerical model of the clastic dike and surrounding matrix for a portion of the excavation. Unsaturated flow through the system was modeled for several recharge rates. The highly heterogeneous nature of the system led to complex behavior, with the relative flux rates in the matrix and clastic dike being highly dependent on the recharge rates that were imposed on the system. The occurrence of saturation-dependent complementary flow networks suggests that the contaminant release history may be important to the choice of remedial actions. Contaminants released under high flux conditions could be inaccessible under low fluxes, and vice versa. This phenomenon may also help explain the occurrence of complex breakthrough patterns of contaminants at compliance planes.
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Rasmussen, T.C., Baldwin Jr., R.H., et al. 2000, 'Tracer vs. Pressure Wave Velocities through Unsaturated Saprolite', Soil Science Society of America Journal, vol. 64, pp. 75-85.
Saprolite is a form of weathered bedrock that is commonly used as the host material at waste disposal sites in the Southeastern Piedmont. However, estimating the unsaturated hydraulic and transport properties of saprolite is difficult due to saprolite's low permeability. We demonstrate the use of short-duration fluid irrigation pulses for maintaining unsaturated conditions in intact saprolite columns. Concomitant Cl- tracer experiments demonstrate that irrigated waters moved through an effective volumetric porosity (0.038–0.108 cm3 cm-3) substantially less than the ambient water-filled porosity (0.44 cm3 cm-3). We observed the unexpected result that irrigation-induced pressure wave velocities (1983–3670 cm d-1) were ~1000 times faster than tracer velocities (2.04–6.00 cm d-1). The relationship between pressure wave velocities and fluid velocities is described using kinematic wave theory, presented for four parametric representations (Brooks–Corey, van Genuchten–Mualem, Broadbridge–White, and the Galileo Number), that predicts fluid pressure velocities to be from approximately two to fifteen times faster than saprolite tracer velocities. None of the kinematic models was able to reproduce observed rapid pressure wave velocities. A hydraulic form of the advection–diffusion equation based on Richards' equation is presented that favorably predicts the shape of pressure response curves only when the kinematic velocity is ignored and the hydraulic diffusivity of the unsaturated saprolite is considered. Based on the advection–diffusion equation, diffusion-dominated soil water pressure wave velocities should decrease with depth, eventually conforming with kinematic wave theory. Pressure pulse velocity monitoring may be an additional tool for estimating unsaturated hydraulic properties in low permeability media.
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Reynolds, W.D. and Zebchuk, W.D. 1996, 'Hydraulic Conductivity in a Clay Soil: Two Measurement Techniques and Spatial Characterization', Soil Science Society of America Journal, vol. 60, pp. 1679-1685.
Infiltration, drainage, and chemical leaching are strongly influenced by the magnitude and spatial distribution of the field-saturated soil hydraulic conductivity (Kfs). The Guelph permeameter (GP) method shows promise as an effective means for field measurement of Kfs and its spatial distribution, but its accuracy in medium- and fine-textured soils is not well established. To further assess its accuracy and effectiveness, the GP method was compared with the auger hole (AH) method at the 0.5-m depth at 68 grid locations in a texturally uniform silty clay soil that had stable but spatially variable structure. The two methods yielded similar geometric mean Kfs values (P < 0.001), as well as similar semivariograms. The two methods were also positively correlated (r = +0.6565, P < 0.0001). We therefore concluded that the two methods gave equivalent estimates of Kfs at this field site, and that the GP method is capable of providing valid estimates of Kfs in at least some fine-textured soils. The Kfs values were not correlated with soil texture, organic C content, or soil surface topography, but were negatively correlated (r = –0.7240 for GP method, r = –0.6070 for AH method, P < 0.0001) with antecedent volumetric water content (θa) measured in situ prior to the GP measurements using a down-hole time domain reflectometry probe. The semivariogram for θa was similar to those for Kfs. These results suggest that the magnitude, range, and pattern of variability of the Kfs measurements were controlled primarily by the well-developed and stable soil structure at the field site, rather than by texture, organ
ic C content, or surface topography.
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Starr, J.L., Sadeghi, A.M., et al. 2005, 'Monitoring and Modeling Lateral Transport through a Large In Situ Chamber', Soil Science Society of America Journal, vol. 69, pp. 1871-1880.
Accurate characterization of lateral transport components is an important step toward a more quantitative assessment of the fate and transport of nutrients and the functionality of riparian/wetland systems. Our specific objectives were: (i) to design an in situ chamber for studying lateral flow under shallow watertable and riparian zone conditions; (ii) to monitor predominantly horizontal transport of non-conservative (NO3) and conservative (Br) tracers in shallow saturated zone of the soil monolith; and (iii) to obtain reaction and transport parameters, and additional insights about the flow and transport inside the soil monolith. HYDRUS-2D model was used to simulate flow and transport of Br and NO3, and to evaluate the applicability of this model to the observed flow and transport. Advective-dispersive equation (ADE) and mobile-immobile zone model (MIM) options were tested using the Br data. The breakthrough curves (BTCs) of NO3 and Br were similar while the concentrations rose, then became distinctly different with NO3 concentrations decreasing much faster. The calibrated denitrification rate of 0.713 ± 0.211 d–1 was about an order and a half of magnitude larger in the loam layer (25–35 cm) than in the overlaying sandy loam layer (0–25 cm) and in the sandy clay loam layer (35–65 cm) below. Up to 60% of the introduced NO3 was lost to denitrification. The methodology presented here allowed the in situ estimation reaction and transport needed for modeling; and it showed a potential to provide detailed information critical for the interpretation of the modeling outcomes performed at field and watershed levels.
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Xiang, J., Scanlon, B.R., et al. 1997, 'A Multistep Constant-head Borehole Test to Determine Field Saturated Hydraulic Conductivity of Layered Soils', Advances in Water Resources, vol. 20, no. 1, pp. 45-57.
Although most field soils are heterogeneous, existing analytical solutions to estimate field saturated hydraulic conductivity Kfs in unsaturated systems assume that the soil is homogeneous. To overcome the limitations of existing analytical soulutions we propose a mulitstep constant head borehole test to evaluate the field saturated hydraulic conductivity of layered media. The field test consists of conducting constant head borehole tests at different depths to correspond to the different layers in the soil. Measurements of water level and the stable flow rate are then used to compute the hydraulic conductivity of each layer. Equations for evaluating the saturated conductivity of each layer are derived. To determine the flow contribution of each layer, a new pressure solution is also presented. One of the assumptions of the proposed analytical solution is that the pressure gradient on the borehole wall of each layer is independent of the hydraulic conductivity of the layer. Comparison of analytical resultes with numerical simulation results show that this assumption is reasonable. The proposed analytical procedure can be used to calculate both the saturated and unsaturated flow components. For deep boreholes with large H/a ratios (≥ 20; H constant depth of water; a borehole radius) the effect of unsaturated flow on the estimated field saturated hydraulic conductivity can be neglected and only one borehole is required. However, for shallow boreholes (H/a <20), the unsaturated flow component is nore negligible and can be estimated by drilling two nearby boreholes of different radii. Field test results are provided to demonstrate the application of the proposed method using deep boreholes in an arid setting. Constant-head borehole tests were repeated at different depths, depending on the number of layers in the system. This test provides a method to determine the vertical distribution of hydraulic conductivity for layered soils which is important for accurate evaluation of subsurface flow and contaminant transport.
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