The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
Binayak P Mohanty - One of the best experts on this subject based on the ideXlab platform.
-
scaling of near saturated hydraulic conductivity measured using disc Infiltrometers
Water Resources Research, 1998Co-Authors: P J Shouse, Binayak P MohantyAbstract:A function relating unsaturated soil hydraulic conductivity K and soil water pressure head h is most important for understanding water flow and chemical transport in the vadose zone. Furthermore, the K(h) function near saturation is critical for describing flow in macropores and other structural voids. The usefulness of similar media scaling and functional normalization to describe the near-saturated hydraulic conductivity function K(h) measured in situ at 296 spatial locations across a heterogeneous agricultural field was tested. Disc (ponded and tension) Infiltrometers were used to measure K(h) at different field positions (corn row, no traffic interrow, and traffic interrow) cutting across different soil types (Nicollet and Clarion loam derived from glacial till material). The K(h) data ranged several orders of magnitude for different field positions and soil types and were found to be statistically different between different field positions. Using a Gardner type K(h) function, relative hydraulic conductivity values, and a hybrid of similar media scaling and functional normalization concepts, all disc infiltrometer data sets were coalesced to a single reference curve. Poor to moderately correlated K and h scale factors did not show any significant spatial structure across the field. A novel finding is that saturated hydraulic conductivities (Ksat) could be successfully used as the scale factor for the near-saturated K(h) functions (e.g., 0-15 cm soil water tension) under all field positions and soil types at the experimental field. Among others, Warrick et al. (1977) and Jarvis and Messing (1995) suggested that further research should be carried out with respect to both experimental technology and scaling con- cepts for an optimum coevolution of techniques addressing soil heterogeneity. More recently, in situ measurement of near- saturated hydraulic conductivlty (K(h)) using disc (ponded and tension) Infiltrometers has opened up new avenues to assess spatial variability of hydraulic properties of field soils. These in situ K(h) measurements are better suited to repre- sent (near-saturated) flow and transport scenarios in the field than K(h) measurements obtained using detached soil cores in the laboratory (Mohanty et al., 1994a). Near-saturated K(h) measurements are important for understanding the influence of macropores and other structural voids in the soil water regime of field soils and useful for multidomain models for soil hydraulic properties. The effects of soil structure and macro- pores might be more reliably predicted, as shown by Mohanty et al. (1997). Spatial variability of these K(h) measurements using different geostatistical and/or scaling concepts need to be studied further for different soils, crops, tillage practices, traf- fic conditions, and other extrinsic/intrinsic field variables. Mo- hanty et al. (1994b, 1996) used geostatistical techniques to an- alyze disc infiltrometer K(h) data under different soil and traffic conditions. To date, only Jarvis and Messing (1995) used a similar media scaling technique to analyze disc infiltrometer K(h) data obtained by means of four to six disc infiltrometer experiments at each of six different soil types in Sweden. The objective of our study was to test the appropriateness of
A W Warrick - One of the best experts on this subject based on the ideXlab platform.
-
alternative analyses of hydraulic data from disc tension Infiltrometers
Water Resources Research, 1993Co-Authors: A A Hussen, A W WarrickAbstract:Hydraulic conductivity values were compared based on alternative analyses of data from disc tension Infiltrometers. The first method was based on a single disc and tension and depends on the estimate of sorptivity and steady state flow. A second method used steady state flow measurements for two different disc radii, 52 and 118 mm. A third method used a single disc with multiple tensions from which steady state flow was obtained at three or more tensions which could be at the same location. A fourth method used a single disc with two tensions from which steady state flow was obtained at two tensions. Finally, values based on soil cores were compared. The results show reasonable agreement between methods for the hydraulic conductivity with the largest differences for data collected for zero tension. For the most part, there were no significant differences in hydraulic conductivity due to the disc infiltrometer radius. A single-disc method with multiple tensions (more than 3 points) and large disc radius gave results which were the most stable, accurate, and repeatable.
-
models for disc Infiltrometers
Water Resources Research, 1992Co-Authors: A W WarrickAbstract:Disc Infiltrometers are popular devices for determining in situ hydraulic properties of unsaturated soils. This paper compares alternative solutions of Richards' equation for both steady state and time-dependent cases. The steady state solutions were in general agreement using alternative hydraulic conductivity functions of the same capillary length scale. Small-time solutions for the nonlinear cases were consistent with linear diffusion from a disc source using an average diffusivity value which is simply related to the capillary length. This offers a refinement over the one-dimensional solution for short times in that the geometric effect of the circular source is included. Simulations for two examples indicate that the approach to the steady state solution may take considerably longer than what is commonly reported in the literature for field applications.
P J Shouse - One of the best experts on this subject based on the ideXlab platform.
-
scaling of near saturated hydraulic conductivity measured using disc Infiltrometers
Water Resources Research, 1998Co-Authors: P J Shouse, Binayak P MohantyAbstract:A function relating unsaturated soil hydraulic conductivity K and soil water pressure head h is most important for understanding water flow and chemical transport in the vadose zone. Furthermore, the K(h) function near saturation is critical for describing flow in macropores and other structural voids. The usefulness of similar media scaling and functional normalization to describe the near-saturated hydraulic conductivity function K(h) measured in situ at 296 spatial locations across a heterogeneous agricultural field was tested. Disc (ponded and tension) Infiltrometers were used to measure K(h) at different field positions (corn row, no traffic interrow, and traffic interrow) cutting across different soil types (Nicollet and Clarion loam derived from glacial till material). The K(h) data ranged several orders of magnitude for different field positions and soil types and were found to be statistically different between different field positions. Using a Gardner type K(h) function, relative hydraulic conductivity values, and a hybrid of similar media scaling and functional normalization concepts, all disc infiltrometer data sets were coalesced to a single reference curve. Poor to moderately correlated K and h scale factors did not show any significant spatial structure across the field. A novel finding is that saturated hydraulic conductivities (Ksat) could be successfully used as the scale factor for the near-saturated K(h) functions (e.g., 0-15 cm soil water tension) under all field positions and soil types at the experimental field. Among others, Warrick et al. (1977) and Jarvis and Messing (1995) suggested that further research should be carried out with respect to both experimental technology and scaling con- cepts for an optimum coevolution of techniques addressing soil heterogeneity. More recently, in situ measurement of near- saturated hydraulic conductivlty (K(h)) using disc (ponded and tension) Infiltrometers has opened up new avenues to assess spatial variability of hydraulic properties of field soils. These in situ K(h) measurements are better suited to repre- sent (near-saturated) flow and transport scenarios in the field than K(h) measurements obtained using detached soil cores in the laboratory (Mohanty et al., 1994a). Near-saturated K(h) measurements are important for understanding the influence of macropores and other structural voids in the soil water regime of field soils and useful for multidomain models for soil hydraulic properties. The effects of soil structure and macro- pores might be more reliably predicted, as shown by Mohanty et al. (1997). Spatial variability of these K(h) measurements using different geostatistical and/or scaling concepts need to be studied further for different soils, crops, tillage practices, traf- fic conditions, and other extrinsic/intrinsic field variables. Mo- hanty et al. (1994b, 1996) used geostatistical techniques to an- alyze disc infiltrometer K(h) data under different soil and traffic conditions. To date, only Jarvis and Messing (1995) used a similar media scaling technique to analyze disc infiltrometer K(h) data obtained by means of four to six disc infiltrometer experiments at each of six different soil types in Sweden. The objective of our study was to test the appropriateness of
-
numerical evaluation of ring Infiltrometers under various soil conditions
Soil Science, 1997Co-Authors: L Wu, M J Roberson, P J ShouseAbstract:Field evaluation of infiltrometer geometry and of soil conditions on infiltration measurements is difficult because ofthe spatial and temporal variability of soil properties and the disturbance of soil by infiltrometer installation. Numerical simulation experiments provide a useful tool for evaluating the infiltration rates measured by various configurations of Infiltrometers and soil conditions. We used an axisymmetric 3-dimensional (3-D) numerical model to simulate water infiltration in single- and double-ring Infiltrometers, as well as one-dimensional (1-D) infiltration for three well studied soil types representing different textures and hydraulic properties. We found that the infiltration rates ofa single-ring infiltrometer were f times greater than the 1-D infiltration, where f is a correction factor dependent on soil initial and boundary conditions and ring geometry. When the configuration of a typical double-ring infiltrometer was used in simulation (inner and outer rings were 20 and 30 cm in diameter, respectively), the simulated infiltration rates were about 80% of the single-ring rates. When the outer-ring diameter was increased to 120 cm (inner-ring diameter kept at 20 cm), the double-ring method-measured infiltration rates were 120 to 133% ofthe 1-D infiltration rates for the three test soils. Compared with the constant head method, falling head infiltration rates dropped as much as 30% as the ponded head dropped from 5 to 1 cm in the sandy clay loam. Layered soil can significantly affect infiltration rates, depending on the position of the wetting front relative to the textural discontinuity and the time ofmeasurement. Time at which the layering starts playing the role can be estimated from f and the cumulative infiltration.
Massimo Iovino - One of the best experts on this subject based on the ideXlab platform.
-
Testing a new automated single ring infiltrometer for Beerkan infiltration experiments
Geoderma, 2016Co-Authors: S. Di Prima, Laurent Lassabatere, Vincenzo Bagarello, Massimo Iovino, Rafael Angulo-jaramilloAbstract:Abstract The Beerkan method along with BEST algorithms is an alternative technique to conventional laboratory or field measurements for rapid and low-cost estimation of soil hydraulic properties. The Beerkan method is simple to conduct but requires an operator to repeatedly pour known volumes of water through a ring positioned at the soil surface. A cheap infiltrometer equipped with a data acquisition system was recently designed to automate Beerkan infiltration experiments. In this paper, the current prototype of the automated infiltrometer was tested to validate its applicability to the Beerkan infiltration experiment under several experimental circumstances. In addition, the accuracy of the estimated saturated soil hydraulic conductivity, Ks, and sorptivity, S, was assessed by applying different BEST algorithms to the data obtained with the infiltrometer. At this purpose, both analytically generated and real experimental data were used. The analytical assessment showed that the use of the infiltrometer along with BEST methods could lead to accurate estimates of the considered soil properties in most cases, which validated the design of the infiltrometer and its combination with BEST algorithms. Loamy soils and high initial water contents led to misestimating Ks and S or to failure of BEST algorithms, but advices about the infiltrometer design were developed to alleviate such problems. A comparison between the automated procedure and the original BEST procedure was made at three field sites in Sicily (Italy). Other experiments were carried out in an infiltration basin located in the pumping well field of Crepieux-Charmy (Lyon, France), in order to assess the ability of the automated infiltrometer to check clogging effects on Ks. The experiments showed that the automatic data collection increased measurement speed, allowed a more efficient data handling and analysis, and reduced sensitivity of the calculated hydraulic parameters on the applied BEST algorithm.
-
testing steady state analysis of single ring and square pressure infiltrometer data
Geoderma, 2016Co-Authors: Vincenzo Bagarello, Massimo IovinoAbstract:Testing reliability of the saturated soil hydraulic conductivity, K-s, estimated by applying the steady-state single-ring (SR) model to the quasi steady-state infiltration rates obtained with a single-ring pressure infiltrometer (PI) increases confidence in the estimated K-s values. Determining a means to estimate K-s from infiltration data collected with a square infiltrometer allows the use of sources of different shapes. Using numerically simulated infiltration rates for six homogeneous soils ranging in texture from sand to silty clay loam, this investigation suggested an overall good performance of the SR model, with estimated K-s values differing by not more than 25% from the true values for the 90% of the 96 considered runs. Larger errors were generally obtained for the silty clay loam soil. Even in this case, however, a small ring radius (0.038 m), a relatively high initial soil water content (initial effective saturation = 0.4) and a relatively high depth of ponding (0.10 m) allowed the obtainment of accurate predictions of K-s (error = 13%) with a run of practically sustainable duration (4 h). The SR model was also usable to analyze quasi steady-state infiltration data collected with a square infiltrometer when infiltration was assumed to occur through a circular source having the same area of the square infiltrometer. With this assumption, the estimates of K-s differed from the true values by not more than a practically negligible 16%. The results of this investigation should help better interpret K-s values obtained with the PI and also improve the experimental methodology, depending on the soil. Moreover, a wider applicability of the infiltrometer techniques, i.e. not limited to a circular source, can be expected. Soil heterogeneity should be taken into account in the future since heterogeneity is common in the field. (C) 2015 Elsevier B.V. All rights reserved.
-
Determining hydraulic properties of a loam soil by alternative infiltrometer techniques
Hydrological Processes, 2015Co-Authors: Vincenzo Alagna, S. Di Prima, Vincenzo Bagarello, Massimo IovinoAbstract:Testing infiltrometer techniques to determine soil hydraulic properties is necessary for specific soils. For a loam soil, the water retention and hydraulic conductivity predicted by the BEST (Beerkan Estimation of Soil Transfer parameters) procedure of soil hydraulic characterization was compared with data collected by more standard laboratory and field techniques. Six infiltrometer techniques were also compared in terms of saturated soil hydraulic conductivity, Ks. BEST yielded water retention values statistically similar to those obtained in the laboratory and Ks values practically coinciding with those determined in the field with the pressure infiltrometer (PI). The unsaturated soil hydraulic conductivity measured with the tension infiltrometer (TI) was reproduced satisfactorily by BEST only close to saturation. BEST, the PI, one-potential experiments with both the TI and the mini disk infiltrometer (MDI), the simplified falling head (SFH) technique and the bottomless bucket (BB) method yielded statistically similar estimates of Ks, differing at the most by a factor of three. Smaller values were obtained with longer and more soil-disturbing infiltration runs. Any of the tested infiltration techniques appears usable to obtain the order of magnitude of Ks at the field site, but the BEST, BB and PI data appear more appropriate to characterize the soil at some stage during a rainfall event. Additional investigations on both similar and different soils would allow development of more general procedures to apply infiltrometer techniques for soil hydraulic characterization. Copyright © 2015 John Wiley & Sons, Ltd.
-
EFFECT OF CONTACT MATERIAL ON TENSION INFILTROMETER MEASUREMENTS
Transactions of the ASABE, 2001Co-Authors: Vincenzo Bagarello, Massimo Iovino, G. TusaAbstract:A layer of contact material is often used to establish and maintain hydraulic contact between a tension infiltrometer membrane and the soil surface. The aims of this study were to determine the change in hydraulic properties of two types of contact materials after repeated use of the materials and to evaluate the effect of contact material on steady–state infiltration rates. Re–using a natural sand contact material resulted in increasing values of satiated hydraulic conductivity, Kst (Kst = 246 to 311 mm h –1 ), due to a progressive loss of fine–textured particles. However, Spheriglass No. 2227 glass spheres, previously proposed as a suitable contact material, maintained stable hydraulic properties after repeated use both in the laboratory and in the field (Kst = 264 to 267 mm h –1 , water entry pressure head hw = –400 to –360 mm, air entry pressure head ha = –640 to –650 mm). The steady–state tension infiltrometer infiltration rate, i0, at a pressure head h0 = –50 mm was reduced by about 30% by removing the contact material from the smoothed and leveled surface of a sandy loam soil. It was concluded that Spheriglass No. 2227 glass spheres are adequate for both use and reuse as tension infiltrometer contact material, and that contact material is required to maintain good hydraulic connection with the soil surface even when the surface has been smoothed and leveled.
Vincenzo Bagarello - One of the best experts on this subject based on the ideXlab platform.
-
Testing a new automated single ring infiltrometer for Beerkan infiltration experiments
Geoderma, 2016Co-Authors: S. Di Prima, Laurent Lassabatere, Vincenzo Bagarello, Massimo Iovino, Rafael Angulo-jaramilloAbstract:Abstract The Beerkan method along with BEST algorithms is an alternative technique to conventional laboratory or field measurements for rapid and low-cost estimation of soil hydraulic properties. The Beerkan method is simple to conduct but requires an operator to repeatedly pour known volumes of water through a ring positioned at the soil surface. A cheap infiltrometer equipped with a data acquisition system was recently designed to automate Beerkan infiltration experiments. In this paper, the current prototype of the automated infiltrometer was tested to validate its applicability to the Beerkan infiltration experiment under several experimental circumstances. In addition, the accuracy of the estimated saturated soil hydraulic conductivity, Ks, and sorptivity, S, was assessed by applying different BEST algorithms to the data obtained with the infiltrometer. At this purpose, both analytically generated and real experimental data were used. The analytical assessment showed that the use of the infiltrometer along with BEST methods could lead to accurate estimates of the considered soil properties in most cases, which validated the design of the infiltrometer and its combination with BEST algorithms. Loamy soils and high initial water contents led to misestimating Ks and S or to failure of BEST algorithms, but advices about the infiltrometer design were developed to alleviate such problems. A comparison between the automated procedure and the original BEST procedure was made at three field sites in Sicily (Italy). Other experiments were carried out in an infiltration basin located in the pumping well field of Crepieux-Charmy (Lyon, France), in order to assess the ability of the automated infiltrometer to check clogging effects on Ks. The experiments showed that the automatic data collection increased measurement speed, allowed a more efficient data handling and analysis, and reduced sensitivity of the calculated hydraulic parameters on the applied BEST algorithm.
-
testing steady state analysis of single ring and square pressure infiltrometer data
Geoderma, 2016Co-Authors: Vincenzo Bagarello, Massimo IovinoAbstract:Testing reliability of the saturated soil hydraulic conductivity, K-s, estimated by applying the steady-state single-ring (SR) model to the quasi steady-state infiltration rates obtained with a single-ring pressure infiltrometer (PI) increases confidence in the estimated K-s values. Determining a means to estimate K-s from infiltration data collected with a square infiltrometer allows the use of sources of different shapes. Using numerically simulated infiltration rates for six homogeneous soils ranging in texture from sand to silty clay loam, this investigation suggested an overall good performance of the SR model, with estimated K-s values differing by not more than 25% from the true values for the 90% of the 96 considered runs. Larger errors were generally obtained for the silty clay loam soil. Even in this case, however, a small ring radius (0.038 m), a relatively high initial soil water content (initial effective saturation = 0.4) and a relatively high depth of ponding (0.10 m) allowed the obtainment of accurate predictions of K-s (error = 13%) with a run of practically sustainable duration (4 h). The SR model was also usable to analyze quasi steady-state infiltration data collected with a square infiltrometer when infiltration was assumed to occur through a circular source having the same area of the square infiltrometer. With this assumption, the estimates of K-s differed from the true values by not more than a practically negligible 16%. The results of this investigation should help better interpret K-s values obtained with the PI and also improve the experimental methodology, depending on the soil. Moreover, a wider applicability of the infiltrometer techniques, i.e. not limited to a circular source, can be expected. Soil heterogeneity should be taken into account in the future since heterogeneity is common in the field. (C) 2015 Elsevier B.V. All rights reserved.
-
Determining hydraulic properties of a loam soil by alternative infiltrometer techniques
Hydrological Processes, 2015Co-Authors: Vincenzo Alagna, S. Di Prima, Vincenzo Bagarello, Massimo IovinoAbstract:Testing infiltrometer techniques to determine soil hydraulic properties is necessary for specific soils. For a loam soil, the water retention and hydraulic conductivity predicted by the BEST (Beerkan Estimation of Soil Transfer parameters) procedure of soil hydraulic characterization was compared with data collected by more standard laboratory and field techniques. Six infiltrometer techniques were also compared in terms of saturated soil hydraulic conductivity, Ks. BEST yielded water retention values statistically similar to those obtained in the laboratory and Ks values practically coinciding with those determined in the field with the pressure infiltrometer (PI). The unsaturated soil hydraulic conductivity measured with the tension infiltrometer (TI) was reproduced satisfactorily by BEST only close to saturation. BEST, the PI, one-potential experiments with both the TI and the mini disk infiltrometer (MDI), the simplified falling head (SFH) technique and the bottomless bucket (BB) method yielded statistically similar estimates of Ks, differing at the most by a factor of three. Smaller values were obtained with longer and more soil-disturbing infiltration runs. Any of the tested infiltration techniques appears usable to obtain the order of magnitude of Ks at the field site, but the BEST, BB and PI data appear more appropriate to characterize the soil at some stage during a rainfall event. Additional investigations on both similar and different soils would allow development of more general procedures to apply infiltrometer techniques for soil hydraulic characterization. Copyright © 2015 John Wiley & Sons, Ltd.
-
EFFECT OF CONTACT MATERIAL ON TENSION INFILTROMETER MEASUREMENTS
Transactions of the ASABE, 2001Co-Authors: Vincenzo Bagarello, Massimo Iovino, G. TusaAbstract:A layer of contact material is often used to establish and maintain hydraulic contact between a tension infiltrometer membrane and the soil surface. The aims of this study were to determine the change in hydraulic properties of two types of contact materials after repeated use of the materials and to evaluate the effect of contact material on steady–state infiltration rates. Re–using a natural sand contact material resulted in increasing values of satiated hydraulic conductivity, Kst (Kst = 246 to 311 mm h –1 ), due to a progressive loss of fine–textured particles. However, Spheriglass No. 2227 glass spheres, previously proposed as a suitable contact material, maintained stable hydraulic properties after repeated use both in the laboratory and in the field (Kst = 264 to 267 mm h –1 , water entry pressure head hw = –400 to –360 mm, air entry pressure head ha = –640 to –650 mm). The steady–state tension infiltrometer infiltration rate, i0, at a pressure head h0 = –50 mm was reduced by about 30% by removing the contact material from the smoothed and leveled surface of a sandy loam soil. It was concluded that Spheriglass No. 2227 glass spheres are adequate for both use and reuse as tension infiltrometer contact material, and that contact material is required to maintain good hydraulic connection with the soil surface even when the surface has been smoothed and leveled.