The Experts below are selected from a list of 270 Experts worldwide ranked by ideXlab platform
Gary W Parkin - One of the best experts on this subject based on the ideXlab platform.
-
the well shape factor for the measurement of soil hydraulic properties using the guelph Permeameter
Soil & Tillage Research, 1998Co-Authors: Zhuanfang F Zhang, P H Groenevelt, Gary W ParkinAbstract:Abstract The Guelph Permeameter method is one of the most frequently used field methods to measure soil hydraulic properties in situ. The well-shape factor which is necessary in the calculation must be obtained visually from a chart. We provide three empirical formulae which can almost perfectly describe the shape factor calculated numerically by Reynolds (see, e.g., Reynolds, 1986 . The Guelph Permeameter method for in situ measurement of field-saturated hydraulic conductivity and matric flux potential. Ph.D. Dissertation. University of Guelph, Guelph, Ont.). We conclude that the three empirical formulae can replace the three shape factor curves in the Operating Instructions of Model 2800K1 Guelph Permeameter ( Soil Moisture Corp., 1987 ).
Okke Batelaan - One of the best experts on this subject based on the ideXlab platform.
-
the usefulness of outcrop analogue air Permeameter measurements for analyzing aquifer heterogeneity quantifying outcrop hydraulic conductivity and its spatial variability
Hydrological Processes, 2014Co-Authors: Bart Rogiers, Koen Beerten, Tuur Smeekens, Dirk Mallants, Matej Gedeon, Marijke Huysmans, Okke BatelaanAbstract:Saturated hydraulic conductivity (K) is one of the most important parameters determining groundwater flow and contaminant transport in both unsaturated and saturated porous media. Although several well-established laboratory methods exist for determining K, in situ measurements of this parameter remain very complex and scale dependent. Often, the limited accessibility of subsurface sediments for sampling means an additional impediment to our ability to quantify subsurface K heterogeneity. One potential solution is the use of outcrops as analogues for subsurface sediments. This paper investigates the use of air Permeameter measurements on outcrops of unconsolidated sediments to quantify K and its spatial heterogeneity on a broad range of sediment types. The Neogene aquifer in northern Belgium is used as a case study for this purpose. To characterize the variability in K, 511 small-scale air permeability measurements were performed on outcrop sediments representative over five of the aquifer's lithostratigraphic units. From these measurements, outcrop-scale equivalent K tensors were calculated using numerical upscaling techniques. Validation of the air Permeameter-based K values by comparison with laboratory constant head K measurements reveals a correlation of 0.93. Overall, the results indicate that hand-held air Permeameters are very efficient and accurate tools to characterize saturated K, as well as its small-scale variability and anisotropy on a broad range of unconsolidated sediments. The studied outcrops further provided a qualitative understanding of aquifer hydrostratigraphy and quantitative estimates about K variability at the centimetre-scale to metre-scale. Copyright © 2013 John Wiley & Sons, Ltd.
Zhuanfang F Zhang - One of the best experts on this subject based on the ideXlab platform.
-
the well shape factor for the measurement of soil hydraulic properties using the guelph Permeameter
Soil & Tillage Research, 1998Co-Authors: Zhuanfang F Zhang, P H Groenevelt, Gary W ParkinAbstract:Abstract The Guelph Permeameter method is one of the most frequently used field methods to measure soil hydraulic properties in situ. The well-shape factor which is necessary in the calculation must be obtained visually from a chart. We provide three empirical formulae which can almost perfectly describe the shape factor calculated numerically by Reynolds (see, e.g., Reynolds, 1986 . The Guelph Permeameter method for in situ measurement of field-saturated hydraulic conductivity and matric flux potential. Ph.D. Dissertation. University of Guelph, Guelph, Ont.). We conclude that the three empirical formulae can replace the three shape factor curves in the Operating Instructions of Model 2800K1 Guelph Permeameter ( Soil Moisture Corp., 1987 ).
Rafael Munozcarpena - One of the best experts on this subject based on the ideXlab platform.
-
estimating the saturated hydraulic conductivity in a spatially variable soil with different Permeameters a stochastic kozeny carman relation
Soil & Tillage Research, 2004Co-Authors: Carlos M Regalado, Rafael MunozcarpenaAbstract:The spatial variability of the saturated hydraulic conductivity ( Ks) of a greenhouse banana plantation volcanic soil was investigated with three different Permeameters: (a) the Philip-Dunne field Permeameter, an easy to implement and low cost device; (b) the Guelph field Permeameter; (c) the constant head laboratory Permeameter. Ks was measured on a 14× 5 array of 2. 5m ×5 m rectangles at 0.15 m depth using the above three methods. Ks differences obtained with the different Permeameters are explained in terms of flow dimensionality and elementary volume explored by the three methods. A sinusoidal spatial variation of Ks was coincident with the underlying alignment of banana plants on the field. This was explained in terms of soil disturbances, such as soil compaction, originated by management practices and tillage. Soil salinity showed some coincidence in space with the hydraulic conductivity, because of the irrigation system distribution, but a causal relationship between the two is however difficult to support. To discard the possibility of an artefact, the original 70 point mesh was doubled by intercalation of a second 14 × 5 grid, such that the laboratory Ks was finally determined on a 140 points 2 . 5m × 2.5 m square grid. Far from diluting such anisotropy this was further strengthened after inclusion of the new 70 points. The porosity ( φ) determined on the same laboratory cores shows a similar sigmoid trend, thus pointing towards a plausible explanation for such variability. A power-law relationship was found between saturated hydraulic conductivity and porosity, Ksαφ n (r 2 = 0.38), as stated by the Kozeny–Carman relation. A statistical reformulation of the Kozeny–Carman relation is proposed that both improved its predictability potential and allows comparisons between different representative volumes, or Ks data sets with different origin. Although the two-field methods: Guelph and Philip-Dunne, also follow a similar alignment trend, this is not so evident, suggesting that additional factors affect Ks measured in the field. Finally, geostatistical techniques such as cross correlograms estimation are used to further investigate this spatial dependence. © 2004 Elsevier B.V. All rights reserved.
-
field evaluation of the new philip dunne Permeameter for measuring saturated hydraulic conductivity
Soil Science, 2002Co-Authors: Rafael Munozcarpena, Carlos M Regalado, Javier Alvarezbenedi, F BartoliAbstract:One of the most sensitive parameters in hydrological models, the saturated hydraulic conductivity (K s ), is also one of the most problematic measurements at field scale in regard to variability and uncertainty. The performance of a new type of simple and inexpensive field Permeameter, the Philip-Dunne Permeameter (PD), is compared with two established alternatives, the laboratory constant head Permeameter (LP) and the field Guelph Permeameter (GP). A PD prototype, a protocol of usage, and a numerical routine to find K s were developed and tested on a 70-point array laid out on an 850-m 2 volcanic soil plot. A power transformation was applied to the raw data using the three methods, and the transformed data were shown to be normally distributed. The LP and GP data were better described by a log-normal distribution, whereas the PD data could also be approximated with a power-normal distribution. A factor of 3 was found to relate PD, LP, and GP hydraulic conductivity estimates, E[Ks], such that E[K s -PD] ≅ 3 E[K s -LP]; E[K s -LP] ≅ 3 E[K s -GP]. Such differences may be explained by the different water infiltration geometries and sample wetted volume for the three methods. The PD has advantages over the other two methods in terms of personnel involved, preparation time, and ease of operation. Additionally, the PD methodology required a smaller number of samples (41% less than GP and 69% less than LP) to estimate the population mean K s . Both PD and GP also give the suction at the wetting front, an important parameter that characterizes the unsaturated flow properties of the soil.
P H Groenevelt - One of the best experts on this subject based on the ideXlab platform.
-
the well shape factor for the measurement of soil hydraulic properties using the guelph Permeameter
Soil & Tillage Research, 1998Co-Authors: Zhuanfang F Zhang, P H Groenevelt, Gary W ParkinAbstract:Abstract The Guelph Permeameter method is one of the most frequently used field methods to measure soil hydraulic properties in situ. The well-shape factor which is necessary in the calculation must be obtained visually from a chart. We provide three empirical formulae which can almost perfectly describe the shape factor calculated numerically by Reynolds (see, e.g., Reynolds, 1986 . The Guelph Permeameter method for in situ measurement of field-saturated hydraulic conductivity and matric flux potential. Ph.D. Dissertation. University of Guelph, Guelph, Ont.). We conclude that the three empirical formulae can replace the three shape factor curves in the Operating Instructions of Model 2800K1 Guelph Permeameter ( Soil Moisture Corp., 1987 ).