scholarly journals Experimental investigation to characterize simple versus multi scaling analysis of hydraulic conductivity at a mesoscale

2021 ◽  
Author(s):  
Guglielmo Federico Antonio Brunetti ◽  
Samuele De Bartolo ◽  
Carmine Fallico ◽  
Ferdinando Frega ◽  
Maria Fernanda Rivera Velásquez ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Spatial Variability ◽  
Hydraulic Properties ◽  
Scaling Laws ◽  
Scaling Analysis ◽  
Field Scale ◽  
Porous Formation ◽  
Proper Design ◽  
First Time

AbstractThe spatial variability of the aquifers' hydraulic properties can be satisfactorily described by means of scaling laws. The latter enable one to relate the small (typically laboratory) scale to the larger (typically formation/regional) ones, therefore leading de facto to an upscaling procedure. In the present study, we are concerned with the spatial variability of the hydraulic conductivity K into a strongly heterogeneous porous formation. A strategy, allowing one to identify correctly the single/multiple scaling of K, is applied for the first time to a large caisson, where the medium was packed. In particular, we show how to identify the various scaling ranges with special emphasis on the determination of the related cut-off limits. Finally, we illustrate how the heterogeneity enhances with the increasing scale of observation, by identifying the proper law accounting for the transition from the laboratory to the field scale. Results of the present study are of paramount utility for the proper design of pumping tests in formations where the degree of spatial variability of the hydraulic conductivity does not allow regarding them as “weakly heterogeneous”, as well as for the study of dispersion mechanisms.

scholarly journals Experimental Investigation to Characterize Simple Vs Multi Scaling Analysis of Hydraulic Conductivity at a Mesoscale

2021 ◽  
Author(s):  
Guglielmo Federico Antonio Brunetti ◽  
Samuele De Bartolo ◽  
Carmine Fallico ◽  
Ferdinando Frega ◽  
Maria Fernanda Rivera Velásquez ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Spatial Variability ◽  
Hydraulic Properties ◽  
Heterogeneous Medium ◽  
Scaling Law ◽  
Scaling Analysis ◽  
Porous Formation ◽  
Proper Design ◽  
First Time

Abstract The spatial variability of the hydraulic properties of aquifers can be satisfactory described by means of scaling law(s). The latter enables one, among the others, to relate the small (typically laboraory) scale to the larger (typically formation/regional) ones, therefore leading de facto to an upscaling procedure. In the present study, we are concerned, with the spatial variability of the hydraulic conductivity k into a strongly heterogeneous porous formation. A strategy, allowing one to identify correctly the single/multiple scaling of k, is applied for the first time to a real case of a large caiison where a strongly heterogeneous medium was packed. In particular, we show how to identify the various scaling ranges with special emphasys to the determination of the related cut-off limits. Finally, we illustrate how the heterogeneity enhances with the increasing scale of observation, by identifying the proper law accounting for the transtion from the laboratory to the field scale. Results of the present study are of paroumnt utility for the proper design of pumping tests in formations where the degree of spatial variability of the hydraulic conductivity does not allow regarding them as “weakly heterogeneous”, as well as for the study of dispersion mechanisms in solute transport.

scholarly journals Spatial Variability of Soil Physical and Hydraulic Properties in a Durum Wheat Field: An Assessment by the BEST-Procedure

Water ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1434 ◽  
Author(s):  
Mirko Castellini ◽  
Anna Maria Stellacci ◽  
Matteo Tomaiuolo ◽  
Emanuele Barca
Keyword(s):  
Spatial Variability ◽  
Crop Yield ◽  
Soil Texture ◽  
Hydraulic Properties ◽  
Wheat Yield ◽  
Structure Stability ◽  
Soil Hydraulic Properties ◽  
Field Scale ◽  
Cross Correlation Analysis ◽  
Soil Hydraulic

Spatial variability of soil properties at the field scale can determine the extent of agricultural yields and specific research in this area is needed. The general objective of this study was to investigate the relationships between soil physical and hydraulic properties and wheat yield at the field scale and test the BEST-procedure for the spatialization of soil hydraulic properties. A simplified version of the BEST-procedure, to estimate some capacitive indicators from the soil water retention curve (air capacity, ACe, relative field capacity, RFCe, plant available water capacity, PAWCe), was applied and coupled to estimates of structure stability index (SSI), determinations of soil texture and measurements of bulk density (BD), soil organic carbon (TOC) and saturated hydraulic conductivity (Ks). Variables under study were spatialized to investigate correlations with observed medium-high levels of wheat yields. Soil physical quality assessment and correlations analysis highlighted some inconsistencies (i.e., a negative correlation between PAWCe and crop yield), and only five variables (i.e., clay + silt fraction, BD, TOC, SSI and PAWCe) were spatially structured. Therefore, for the soil–crop system studied, application of the simplified BEST-procedure did not return completely reliable results. Results highlighted that (i) BD was the only variable selected by stepwise analysis as a function of crop yield, (ii) BD showed a spatial distribution in agreement with that detected for crop yield, and (iii) the cross-correlation analysis showed a significant positive relationship between BD and wheat yield up to a distance of approximately 25 m. Such results have implications for Mediterranean agro-environments management. In any case, the reliability of simplified measurement methods for estimating soil hydraulic properties needs to be further verified by adopting denser measurements grids in order to better capture the soil spatial variability. In addition, the temporal stability of observed spatial relationships, i.e., between BD or soil texture and crop yields, needs to be investigated along a larger time interval in order to properly use this information for improving agronomic management.

scholarly journals Reconsideration at Field Scale of the Relationship between Hydraulic Conductivity and Porosity: The Case of a Sandy Aquifer in South Italy

2014 ◽  
Vol 2014 ◽  
pp. 1-15 ◽  
Author(s):  
Carmine Fallico
Keyword(s):  
Grain Size ◽  
Hydraulic Conductivity ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Effective Porosity ◽  
Grain Size Analysis ◽  
Size Analysis ◽  
Strict Sense ◽  
Field Scale

To describe flow or transport phenomena in porous media, relations between aquifer hydraulic conductivity and effective porosity can prove useful, avoiding the need to perform expensive and time consuming measurements. The practical applications generally require the determination of this parameter at field scale, while most of the empirical and semiempirical formulas, based on grain size analysis and allowing determination of the hydraulic conductivity from the porosity, are related to the laboratory scale and thus are not representative of the aquifer volumes to which one refers. Therefore, following the grain size distribution methodology, a new experimental relation between hydraulic conductivity and effective porosity, representative of aquifer volumes at field scale, is given for a confined aquifer. The experimental values used to determine this law were obtained for both parameters using only field measurements methods. The experimental results found, also if in the strict sense valid only for the investigated aquifer, can give useful suggestions for other alluvial aquifers with analogous characteristics of grain-size distribution. Limited to the investigated range, a useful comparison with the best known empirical formulas based on grain size analysis was carried out. The experimental data allowed also investigation of the existence of a scaling behaviour for both parameters considered.

scholarly journals Analysis of Hydraulic Properties of Indian Forest Soil

2018 ◽  
Vol 7 (1) ◽  
pp. 12
Author(s):  
Shwetha Prasanna
Keyword(s):  
Hydraulic Conductivity ◽  
Spatial Variability ◽  
Soil Properties ◽  
Forest Soil ◽  
Hydraulic Properties ◽  
Water Retention ◽  
Saturated Hydraulic Conductivity ◽  
Soil Hydraulic Properties ◽  
Soil Hydraulic ◽  
High Degree

Soils are a product of the factors of formation and continuously change over the earth’s surface. The analysis of the spatial variability of soil properties is important for land management and construction of an ecological environment. Soils are characterized by high degree of spatial variability due to the combined effect of physical, chemical or biological processes that operate with different intensities and at different scales. The spatial variability of soil hydraulic properties helps us to find the subsurface flux of water. The most frequently used hydraulic properties are soil water retention curve and saturated hydraulic conductivity. Both these hydraulic properties exhibit a high degree of spatial and temporal variability. The primary objective of this study was to analyze the spatial variability of hydraulic properties of forest soils of Pavanje river basin. Correlation analysis technique has been used to analyze various soil properties. Spatial variability of the forested hillslope soils at different depths varied considerably among the soil hydraulic properties. The spatial variability of water retention at all the different pressure head is low at the top layers, and increases towards the bottom layers. The saturated hydraulic conductivity is almost same in the top layers, but more in the bottom layers of forest soil.

scholarly journals Scale-dependency and spatial variability of soil hydraulic properties

2004 ◽  
Author(s):  
Renduo Zhang ◽  
David Russo
Keyword(s):  
Spatial Variability ◽  
Water Flow ◽  
Hydraulic Properties ◽  
Small Scale ◽  
Scale Dependency ◽  
Soil Hydraulic Properties ◽  
Field Scale ◽  
Essential Information ◽  
Lab Experiments ◽  
Soil Hydraulic

Water resources assessment and protection requires quantitative descriptions of field-scale water flow and contaminant transport through the subsurface, which, in turn, require reliable information about soil hydraulic properties. However, much is still unknown concerning hydraulic properties and flow behavior in heterogeneous soils. Especially, relationships of hydraulic properties changing with measured scales are poorly understood. Soil hydraulic properties are usually measured at a small scale and used for quantifying flow and transport in large scales, which causes misleading results. Therefore, determination of scale-dependent and spatial variability of soil hydraulic properties provides the essential information for quantifying water flow and chemical transport through the subsurface, which are the key processes for detection of potential agricultural/industrial contaminants, reduction of agricultural chemical movement, improvement of soil and water quality, and increase of agricultural productivity. The original research objectives of this project were: 1. to measure soil hydraulic properties at different locations and different scales at large fields; 2. to develop scale-dependent relationships of soil hydraulic properties; and 3. to determine spatial variability and heterogeneity of soil hydraulic properties as a function of measurement scales. The US investigators conducted field and lab experiments to measure soil hydraulic properties at different locations and different scales. Based on the field and lab experiments, a well-structured database of soil physical and hydraulic properties was developed. The database was used to study scale-dependency, spatial variability, and heterogeneity of soil hydraulic properties. An improved method was developed for calculating hydraulic properties based on infiltration data from the disc infiltrometer. Compared with the other methods, the proposed method provided more accurate and stable estimations of the hydraulic conductivity and macroscopic capillary length, using infiltration data collected atshort experiment periods. We also developed scale-dependent relationships of soil hydraulic properties using the fractal and geostatistical characterization. The research effort of the Israeli research team concentrates on tasks along the second objective. The main accomplishment of this effort is that we succeed to derive first-order, upscaled (block effective) conductivity tensor, K'ᵢⱼ, and time-dependent dispersion tensor, D'ᵢⱼ, i,j=1,2,3, for steady-state flow in three-dimensional, partially saturated, heterogeneous formations, for length-scales comparable with those of the formation heterogeneity. Numerical simulations designed to test the applicability of the upscaling methodology to more general situations involving complex, transient flow regimes originating from periodic rain/irrigation events and water uptake by plant roots suggested that even in this complicated case, the upscaling methodology essentially compensated for the loss of sub-grid-scale variations of the velocity field caused by coarse discretization of the flow domain. These results have significant implications with respect to the development of field-scale solute transport models capable of simulating complex real-world scenarios in the subsurface, and, in turn, are essential for the assessment of the threat posed by contamination from agricultural and/or industrial sources.  

scholarly journals How does PTF Interpret Soil Heterogeneity? A Stochastic Approach Applied to a Case Study on Maize in Northern Italy

Water ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 275 ◽  
Author(s):  
Angelo Basile ◽  
Antonello Bonfante ◽  
Antonio Coppola ◽  
Roberto De Mascellis ◽  
Salvatore Falanga Bolognesi ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Spatial Variability ◽  
Soil Water ◽  
Hydraulic Properties ◽  
Water Retention ◽  
Pedotransfer Functions ◽  
Water Retention Curve ◽  
Real Field ◽  
Retention Curve

Soil water balance on a local scale is generally achieved by applying the classical nonlinear Richards equation that requires hydraulic properties, namely, water retention and hydraulic conductivity functions, to be known. Its application in agricultural systems on field or larger scales involves three major problems being solved, related to (i) the assessment of spatial variability of soil hydraulic properties, (ii) accounting for this spatial variability in modelling large-scale soil water flow, and (iii) measuring the effects of such variability on real field variables (e.g., soil water storage, biomass, etc.). To deal with the first issue, soil hydraulic characterization is frequently performed by using the so-called pedotransfer functions (PTFs), whose effectiveness in providing the actual information on spatial variability has been questioned. With regard to the second problem, the variability of hydraulic properties at the field scale has often been dealt with using a relatively simple approach of considering soils in the field as an ensemble of parallel and statistically independent tubes, assuming only vertical flow. This approach in dealing with spatial variability has been popular in the framework of a Monte Carlo technique. As for the last issue, remote sensing seems to be the only viable solution to verify the pattern of variability, going by several modelling outputs which have considered the soil spatial variability. Based on these premises, the goals of this work concerning the issues discussed above are the following: (1) analyzing the sensitivity of a Richards-based model to the measured variability of θ(h) and k(θ) parameters; (2) establishing the predictive capability of PTF in terms of a simple comparison with measured data; and (3) establishing the effectiveness of use of PTF by employing as data quality control an independent and spatially distributed estimation of the Above Ground Biomass (AGB). The study area of approximately 2000 hectares mainly devoted to maize forage cultivation is located in the Po plain (Lodi), in northern Italy. Sample sites throughout the study area were identified for hydropedological analysis (texture, bulk density, organic matter content, and other chemical properties on all the samples, and water retention curve and saturated hydraulic conductivity on a sub-set). Several pedotransfer functions were tested; the PTF‒Vereckeen proved to be the best one to derive hydraulic properties of the entire soil database. The Monte Carlo approach was used to analyze model sensitivity to two measured input parameters: the slope of water retention curve (n) and the saturated hydraulic conductivity (k0). The analysis showed sensitivity of the simulated process to the parameter n being significantly higher than to k0, although the former was much less variable. The PTFs showed a smoothing effect of the output variability, even though they were previously validated on a set of measured data. Interesting positive and significant correlations were found between the n parameter, from measured water retention curves, and the NDVI (Normalized Difference Vegetation Index), when using multi-temporal (2004–2018) high resolution remotely sensed data on maize cultivation. No correlation was detected when the n parameter derived from PTF was used. These results from our case study mainly suggest that: (i) despite the good performance of PTFs calculated via error indexes, their use in the simulation of hydrological processes should be carefully evaluated for real field-scale applications; and (ii) the NDVI index may be used successfully as a proxy to evaluate PTF reliability in the field.

Multifractal analysis of soil hydraulic properties in arid areas

Soil Research ◽  
2016 ◽  
Vol 54 (8) ◽  
pp. 914 ◽  
Author(s):  
N. Pahlevan ◽  
M. R. Yazdani ◽  
A. A. Zolfaghari ◽  
M. Ghodrati
Keyword(s):  
Spatial Variability ◽  
Soil Properties ◽  
Soil Water ◽  
Multifractal Analysis ◽  
Hydraulic Properties ◽  
Water Retention ◽  
Scaling Analysis ◽  
Soil Hydraulic Properties ◽  
Soil Water Retention ◽  
Soil Hydraulic

Physical and hydraulic properties of soil are variable at different spatial scales. This indicates the necessity of understanding spatial patterns of soil properties. Scaling analysis, such as multifractal analysis, has been used to determine the spatial variability of soil properties. There are however limited numbers of studies concerning the applications of multifractal techniques applied to characterise spatial variability of soil properties in arid lands. The objective of this study was to quantify the scaling patterns of soil properties measured across a transect and to apply multifractal analysis in arid land areas. A transect with a length of 4.80km was selected, and soil properties were measured at 0–20cm depth every 145m along the transect. The soil properties analysed were: texture (sand, silt, clay), pH, electrical conductivity (EC), bulk density (BD), soil hydraulic properties (saturated hydraulic conductivity Ks and the van Genuchten soil water-retention equation’s parameters nv and αv), saturated water content (θs), and the slope of the soil water-retention curve at its inflection point (S). Results showed that the variability of pH and BD was characterised by quasi-monofractal behaviour. Results showed that soil hydraulic properties such as Ks, αn, nv, S, and θs were characterised by higher multifractal indices in the transects. EC showed the highest tendency to a multifractal type of scaling or the higher degree of multifractality.

Site-Specific Management of Flow and Transport in Homogeneous and Structured Soils

1999 ◽  
Author(s):  
D. J. Mulla ◽  
A. P. Mallawatantri
Keyword(s):  
Hydraulic Conductivity ◽  
Spatial Variability ◽  
Solute Transport ◽  
Pore Water ◽  
Water Velocity ◽  
Soil Science ◽  
Hydrodynamic Dispersion ◽  
Field Scale ◽  
Frequency Distributions ◽  
Pore Water Velocity

Among research publications in soil science, few have had a greater impact than those by Nielsen et al. (1973) or Biggar and Nielsen (1976). According to Science Citation Index, the former paper, entitled “Spatial variability of field-measured soilwater properties,” has been cited by scientific peers over 390 times. The 1976 paper, entitled “Spatial variability of the leaching characteristics of a field soil,” has been cited over 232 times. Experimental work presented in both papers represents the first-ever attempt at a large field-scale study of steady-state water and solute transport (Wagenet, 1986). Among the seminal findings of these two papers were as follows: (1) extensive spatial variability existed in soil hydraulic and solute transport properties within a relatively homogeneous field (important in the work of Pilgrim et al., 1982; Addiscott and Wagenet, 1985; Feddes et al., 1988; van dcr Molen and van Ommen, 1988); (2) soil water content, bulk density, and soil particle size exhibited normal frequency distributions, while distributions for hydraulic conductivity, hydraulic diffusivity, pore water velocity, and hydrodynamic dispersion were lognormal (work extended by van der Pol et al.. 1977; Rao et al., 1979); (3) frequency distributions were far superior to field-average parameter values (especially for lognormally distributed properties) in describing field transport behavior (demonstrated by Rao et al., 1979; Trangmar et al., 1985); (4) a simple unit hydraulic gradient method was shown to estimate saturated hydraulic conductivity accurately (results extended by Libardi et al., 1980; van Genuchten and Leij, 1992); (5) good correspondence was found between solute velocity and pore water velocity (key assumption in Jury and Fluhler, 1992); (6) and theoretical predictions of a linear relation between hydrodynamic dispersion and pore water velocity were shown to be obeyed at the field scale (result used widely by solute transport modelers, as discussed in Nielsen et al., 1986). The seminal works by Nielsen et al. (1973) and Biggar and Nielsen (1976) produced several new directions in soil science and vadose zone hydrology research. The most interesting was a series of papers that rejected the theoretical basis and practicality of using deterministic equations, and instead introduced stochastic approaches to describe field-scale water and solute fluxes.

Soil Properties and Water Movement

1999 ◽  
Author(s):  
J.-Y. Parlance ◽  
T. S. Steenhuis
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Hydraulic Properties ◽  
Volumetric Water Content ◽  
Richards Equation ◽  
Field Scale ◽  
Soil Hydraulic Parameters ◽  
Soil Hydraulic ◽  
Definition Of

For all spatial scales, from pore through local and field, to a watershed, interaction of the land surface with the atmosphere will be one of the crucial topics in hydrology and environmental sciences over the forthcoming years. The recent lack of water in many parts of the world shows that there is an urgent need to assess our knowledge on the soil moisture dynamics. The difficulty of parameterization of soil hydrological processes lies not only in the nonlinearity of the unsaturated flow equation but also in the mismatch between the scales of measurements and the scale of model predictions. Most standard measurements of soil physical parameters provide information only at the local scale and highlight the underlying variability in soil hydrological characteristics. The efficiency of soil characteristic parameterization for the field scale depends on the clear definition of the functional relationships and parameters to be measured, and on the development of possible methods for the determination of soil characteristics with a realistic use time and effort. The soil’s hydraulic properties that affect the flow behavior can be expressed by a soil water retention curve that describes the relation between volumetric water content, θ(L3L3), and soil water pressure, h(L), plus the relation between volumetric water content and hydraulic conductivity, K(L/T). In the next section, the determination of soil hydraulic parameters is first discussed for local and field scale. Then, we show how the pore-scale processes can be linked to soil hydraulic properties. These properties are then used in some of the modern methods that use integral and superposition solutions of Richards’ equation for infiltration and water flow problems for both stable and preferential types of flows. Finally, some practical aspects for watersheds are discussed to highlight the difficulties encountered when large-scale predictions are needed.

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