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1

Hydraulic Properties of Unsaturated Soils  

Technology Transfer Automated Retrieval System (TEKTRAN)

Many agrophysical applications require knowledge of the hydraulic properties of unsaturated soils. These properties reflect the ability of a soil to retain or transmit water and its dissolved constituents. The objective of this work was to develop an entry for the Encyclopedia of Agrophysics that w...

2

BOREAS HYD-1 Soil Hydraulic Properties  

NASA Technical Reports Server (NTRS)

The Boreal Ecosystem-Atmosphere Study (BOREAS) Hydrology (HYD)-1 team coordinated a program of data collection to measure and monitor soil properties in collaboration with other science team measurement needs. This data set contains soil hydraulic properties determined at the Northern Study Area (NSA) and Southern Study Area (SSA) flux tower sites based on analysis of in situ tension infiltrometer tests and laboratory-determined water retention from soil cores collected during the 1994-95 field campaigns. Results from this analysis are saturated hydraulic conductivity, and fitting parameters for the van Genuchten-Mualem soil hydraulic conductivity and water retention function at flux tower sites. The data are contained in tabular ASCII files. The HYD-01 soil hydraulic properties data are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The data files are available on a CD-ROM (see document number 20010000884).

Hall, Forrest G. (Editor); Knapp, David E. (Editor); Kelly, Shaun F.; Stangel, David E.; Smith, David E. (Technical Monitor)

2000-01-01

3

Scaling hydraulic properties of a macroporous soil Binayak P. Mohanty  

E-print Network

Scaling hydraulic properties of a macroporous soil Binayak P. Mohanty U.S. Salinity Laboratory, Riverside, California Abstract. Macroporous soils exhibit significant differences in their hydraulic properties for different pore domains. Multimodal hydraulic functions may be used to describe

Mohanty, Binayak P.

4

Soil Texture Triangle: Hydraulic Properties Calculator  

NSDL National Science Digital Library

Dr. Keith E. Saxton from Washington State Universities Department of Biological Systems Engineering offers the Soil Texture Triangle-Hydraulic Properties Calculator Web site. By simply entering its percent sand and clay, this online calculator allows users to find the wilting point, field capacity, bulk density, saturation, saturated hydraulic conductivity, and available water of particular soils. A great resource for researchers and professionals, the utility can even be downloaded free of charge to use on your own computer as a MS-DOS program. .

Saxton, Keith E., 1937-

5

Effect of Application of Surfactants on Hydraulic Properties of Soils  

Microsoft Academic Search

This study explores the effect of surfactants, commonly found in detergents, on the hydraulic properties of soils. The soil properties examined included hydraulic conductivity, infiltration characteristics, and effective suction at the wetting front, capillary rise and soil penetrability. Two agricultural soils—a loam and a sandy loam, and three surfactants—one anionic surfactant (Sulphonic) and two non-ionic surfactants (Rexol and Rexonic), were

M. Abu-Zreig; R. P. Rudra; W. T. Dickinson

2003-01-01

6

Empirical equations for some soil hydraulic properties  

Microsoft Academic Search

with a power function relating soil moisture and hydraulic conductivitymis used to derive a formula for the wetting front suction required by the Green-Ampt equation. Representative parameters for the moisture charac- teristic, the wetting front suction, and the sorptivity, a parameter in the infiltration equation derived by Philip (1957), are computed by using the desorption data of Holtan et al.

Roger B. Clapp; George M. Hornberger

1978-01-01

7

Effective Soil Hydraulic Properties for Infiltration and Redistribution in Unsaturated Zone  

Microsoft Academic Search

The fundamental soil hydraulic properties that control hydrologic processes are the soil water potential and the hydraulic conductivity as functions of soil water content. Average\\/effective soil hydraulic properties are essential for many large scale hydrological, environmental or climate studies. In this study, we investigate 1) how the hydrologic processes impact on the effective hydraulic properties; 2) how the effective hydraulic

J. Zhu; D. Sun

2009-01-01

8

USING ENSEMBLE PREDICTIONS TO SIMULATE FIELD-SCALE SOIL WATER TIME SERIES WITH UPSCALED AND DOWNSCALED SOIL HYDRAULIC PROPERTIES  

Technology Transfer Automated Retrieval System (TEKTRAN)

Simulations of soil water flow require measurements of soil hydraulic properties which are particularly difficult at field scale. Laboratory measurements provide hydraulic properties at scales finer than the field scale, whereas pedotransfer functions (PTFs) integrate information on hydraulic prope...

9

FIELD DETERMINATION OF SOIL HYDRAULIC AND CHEMICAL TRANSPORT PROPERTIES  

Technology Transfer Automated Retrieval System (TEKTRAN)

Hydraulic and chemical transport properties are the major inputs in predictive models that simulate the movement of water and chemicals through the vadose zone. However, there is a lack of field measurements of such properties to verify models describing water and chemical movement through the soil...

10

LANDSCAPE AND CONSERVATION MANAGEMENT EFFECTS ON HYDRAULIC PROPERTIES ON A CLAYPAN-SOIL TOPOSEQUENCE  

Technology Transfer Automated Retrieval System (TEKTRAN)

Information on effects of landscape and its interaction with management on soil hydraulic properties is scarce. This study investigated effects and interactions of landscape position and conservation management systems on soil bulk density, saturated hydraulic conductivity (Ksat), soil water retenti...

11

ESTIMATION OF SURFACE SOIL HYDRAULIC PROPERTIES FROM REMOTELY SENSED SURFACE SOIL MOISTURE  

Technology Transfer Automated Retrieval System (TEKTRAN)

Remotely sensed surface soil water content was used to estimate near-surface soil hydraulic properties based on 2-day drainage data in the Little Washita River Experimental Watershed in south central Oklahoma. Characterization of hydraulic conductivity based on 2-days drainage in the field is relate...

12

Hydraulic properties of mine soils with embedded lignitic fragments  

NASA Astrophysics Data System (ADS)

Lignitic mine soils represent a typical two-scale dual-porosity medium consisting of a technogenic mixture of overburden sediments that include lignitic components as dust and as porous fragments embedded within a mostly coarse-textured matrix. Flow and transport processes in such soils are not sufficiently understood to predict the course of soil reclamation or of mine drainage. The objective of this contribution is to identify the most appropriate conceptual model for describing small-scale heterogeneity effects on flow on the basis of the physical structure of the system. Two-domain hydraulic properties were derived based on multi-step outflow data. The interface between fragments and sandy matrix represents an additional pore region that cannot be derived from information of either the matrix or the fragments. New information is required on the geometry (size and shape) and spatial distribution of fragments to describe the properties of the mine soil as a whole.

Gerke, Horst H.

2014-05-01

13

MULTIMODEL ENSEMBLE PREDICTION OF SOIL HYDRAULIC PROPERTIES TO SIMULATE FIELD-SCALE SOIL WATER FLOW  

Technology Transfer Automated Retrieval System (TEKTRAN)

Using pedotransfer functions (PTF) to estimate soil hydraulic properties may be necessary in soil water flow simulations for large-scale projects or in a pilot studies. The accuracy of a PTF outside of its development dataset is unknown. Existence of several models that are developed and tested in o...

14

Determination of Soil Hydraulic Properties Using Magnetic Resonance Techniques and Classical Soil Physics Measurements  

NASA Astrophysics Data System (ADS)

Water and solute movement as any other transport processes through soil are influenced by the hydraulic properties of the soils. The heterogeneities of the soils imply heterogeneous spatial distribution of the hydraulic properties leading to heterogeneous distribution of soil water content. This may affects the water availability for plant growth, the groundwater contamination and nutrients losses within the root zone. The measurement techniques available today for the estimation of soil hydraulic parameters do not account for the heterogeneity of the sample and treat each measurement sample as a homogeneous representative volume. On the other side natural soils contain large heterogeneities mostly in terms of inclusions of different materials. Therefore the purpose of this study is to estimate soil hydraulic properties of a heterogeneous sample by combining classical multi-step-outflow (MSO) with magnetic resonance imaging (MRI) experiments. MSO experiments were performed on a sample filled with sand and sand-clay mixture in a coaxial structure. During each pressure application MRI images at 4.7 T (200 MHz) were recorded using a pure phase-encoding MRI sequence in order to provide information about the soil water content at specific locations within the coaxial sample. The recorded cumulative outflow and water content data were used as input data in the inversion of the MSO experiment. For the simulation and inversion of the MSO experiment we used the hydrological model HYDRUS-2D3D in which the initial hydraulic parameters of the two materials were estimated based on CPMG-T2 relaxation measurements on homogeneous sub-samples. The results show conclusively that the combination of the two MRI and MSO methods leads to a unique estimation of the hydraulic properties of two materials simultaneously.

Stingaciu, Laura R.; Weihermüller, Lutz; Pohlmeier, Andreas; Stapf, Siegfried; Vereecken, Harry

2011-03-01

15

Influence of Thinning Loblolly Pine (Pinus taeda L.) on Hydraulic Properties of an Organic Soil  

Microsoft Academic Search

The impact of forest operations on soil properties has been a concern in forest management over the past 30 years. The objective of this study was to evaluate the impact of forest thinning operations on soil hydraulic properties of a shallow organic (Belhaven series) soil in the Tidewater region of North Carolina. Soil physical properties were evaluated in a nested

J. McFero; Grace III; G. W. Andrews; R. W. Skaggs; William Neal Reynolds; D. Keith Cassel

16

SENSITIVITY OF TILE DRAINAGE FLOW AND CROP YIELD ON MEASURED AND CALIBRATED SOIL HYDRAULIC PROPERTIES  

Technology Transfer Automated Retrieval System (TEKTRAN)

Process-based agricultural systems models require detailed description of soil hydraulic properties that are usually not available. The objectives of this study were to evaluate the sensitivity of model simulation results to uncertainty in measured soil hydraulic properties and to compare simulation...

17

SOIL HYDRAULIC PROPERTIES OF CROPLAND COMPARED WITH REESTABLISHED AND NATIVE GRASSLAND  

Technology Transfer Automated Retrieval System (TEKTRAN)

Conversion of cropland to perennial grasses will, over time, produce changes in soil hydraulic properties. We conducted a study to characterize and compare soil hydraulic properties on adjacent native grassland, recently tilled cropland, and reestablished grassland in the Conservation Reserve Progra...

18

Environmental and management influences on temporal variability of near saturated soil hydraulic properties.  

PubMed

Structural porosity is a decisive property for soil productivity and soil environmental functions. Hydraulic properties in the structural range vary over time in response to management and environmental influences. Although this is widely recognized, there are few field studies that determine dominant driving forces underlying hydraulic property dynamics. During a three year field experiment we measured temporal variability of soil hydraulic properties by tension infiltrometry. Soil properties were characterized by hydraulic conductivity, effective macroporosity and Kosugi's lognormal pore size distribution model. Management related influences comprised three soil cover treatment (mustard and rye vs. fallow) and an initial mechanical soil disturbance with a rotary harrow. Environmental driving forces were derived from meteorological and soil moisture data. Soil hydraulic parameters varied over time by around one order of magnitude. The coefficient of variation of soil hydraulic conductivity K(h) decreased from 69.5% at saturation to 42.1% in the more unsaturated range (- 10 cm pressure head). A slight increase in the Kosugi parameter showing pore heterogeneity was observed under the rye cover crop, reflecting an enhanced structural porosity. The other hydraulic parameters were not significantly influenced by the soil cover treatments. Seedbed preparation with a rotary harrow resulted in a fourfold increase in macroporosity and hydraulic conductivity next to saturation, and homogenized the pore radius distribution. Re-consolidation after mechanical loosening lasted over 18 months until the soil returned to its initial state. The post-tillage trend of soil settlement could be approximated by an exponential decay function. Among environmental factors, wetting-drying cycles were identified as dominant driving force explaining short term hydraulic property changes within the season (r(2) = 0.43 to 0.59). Our results suggested that beside considering average management induced changes in soil properties (e.g. cover crop introduction), a dynamic approach to hydrological modeling is required to capture over-seasonal (tillage driven) and short term (environmental driven) variability in hydraulic parameters. PMID:24748683

Bodner, G; Scholl, P; Loiskandl, W; Kaul, H-P

2013-08-01

19

DETERMINATION OF SOIL HYDRAULIC PROPERTIES IN A PART OF HINDON RIVER CATCHMENT USING SOILPROP SOFTWARE  

E-print Network

DETERMINATION OF SOIL HYDRAULIC PROPERTIES IN A PART OF HINDON RIVER CATCHMENT USING SOILPROP) and unsaturated hydraulic conductivity (K). To model the retention and movement of water and chemicals and hydraulic conductivity. It is often convenient to represent these functions by means of relatively simple

Kumar, C.P.

20

Laboratory evaporation experiments in undisturbed peat columns for determining peat soil hydraulic properties  

NASA Astrophysics Data System (ADS)

One of the key parameters controlling greenhouse gas (GHG) emissions from organic soils is water table depth. Thus, a detailed analysis of the hydrology is essential for an accurate spatial upscaling of the information of local GHG emission measurements to the regional and national scale. For the interpretation and numerical modeling of water table fluctuations, knowledge about soil hydraulic parameters is crucial. In contrast to mineral soils, the hydraulic properties of organic soils differ in several aspects. Due to the high amount of organic components, strong heterogeneity, and shrinkage and swelling of peat, accompanied by changing soil volume and bulk density, it is difficult to describe peat soil moisture dynamics with standard hydraulic functions developed for mineral soils. The objective of this study was to determine soil hydraulic properties for various undisturbed peat columns (diameter: 30 cm, height: 20 cm). Laboratory evaporation experiments were conducted for peat soils from five different test sites of the German joint research project "Organic Soils". Due to different land use histories, the peat samples covered a broad range of degradation states, which is known to strongly influence peat soil hydraulic properties. Pressure head, moisture content, weight loss and water level were monitored during the evaporation experiment. In numerical simulations using HYDRUS-1D the experimental data were used for an inverse-estimation of the soil hydraulic parameters using "shuffled complex evolution" and "covariance matrix adaption" optimization schemes. Besides the commonly applied van Genuchten-Mualem parameterization, several alternative soil parameterizations are evaluated.

Dettmann, Ullrich; Frahm, Enrico; Bechtold, Michel

2013-04-01

21

Effects of long-term soil and crop management on soil hydraulic properties for claypan soils  

Technology Transfer Automated Retrieval System (TEKTRAN)

Regional and national soil maps have been developed along with associated soil property databases to assist users in making land management decisions based on soil characteristics. These soil properties include average values from soil characterization for each soil series. In reality, these propert...

22

Effects of native forest restoration on soil hydraulic properties, Auwahi, Maui, Hawaiian Islands  

E-print Network

to restore dryland forests to bring back native species and reduce erosion. The reestablishment of native hydraulic properties to favor invasive species. We hypothesize that reestablishment of native species mayEffects of native forest restoration on soil hydraulic properties, Auwahi, Maui, Hawaiian Islands K

23

Effective soil hydraulic properties in space and time: some field data analysis and modeling concepts  

Technology Transfer Automated Retrieval System (TEKTRAN)

Soil hydraulic properties, which control surface fluxes and storage of water and chemicals in the soil profile, vary in space and time. Spatial variability above the measurement scale (e.g., soil area of 0.07 m2 or support volume of 14 L) must be upscaled appropriately to determine “effective” hydr...

24

Tillage Effects on Soil Hydraulic Properties in Space and Time: State of the Science  

Technology Transfer Automated Retrieval System (TEKTRAN)

Soil tillage practices can affect soil hydraulic properties and processes in space and time with consequent and coupled effects on chemical movement and plant growth. This literature review addresses the quantitative effects of soil tillage and associated management (e.g., crop residues) on the tem...

25

Discrimination of soil hydraulic properties by combined thermal infrared and microwave remote sensing  

NASA Technical Reports Server (NTRS)

Using the De Vries models for thermal conductivity and heat capacity, thermal inertia was determined as a function of soil moisture for 12 classes of soil types ranging from sand to clay. A coupled heat and moisture balance model was used to describe the thermal behavior of the top soil, while microwave remote sensing was used to estimate the soil moisture content of the same top soil. Soil hydraulic parameters are found to be very highly correlated with the combination of soil moisture content and thermal inertia at the same moisture content. Therefore, a remotely sensed estimate of the thermal behavior of the soil from diurnal soil temperature observations and an independent remotely sensed estimate of soil moisture content gives the possibility of estimating soil hydraulic properties by remote sensing.

Vandegriend, A. A.; Oneill, P. E.

1986-01-01

26

Environmental and management impacts on temporal variability of soil hydraulic properties  

NASA Astrophysics Data System (ADS)

Soil hydraulic properties underlie temporal changes caused by different natural and management factors. Rainfall intensity, wet-dry cycles, freeze-thaw cycles, tillage and plant effects are potential drivers of the temporal variability. For agricultural purposes it is important to determine the possibility of targeted influence via management. In no-till systems e.g. root induced soil loosening (biopores) is essential to counteract natural soil densification by settling. The present work studies two years of temporal evolution of soil hydraulic properties in a no-till crop rotation (durum wheat-field pea) with two cover crops (mustard and rye) having different root systems (taproot vs. fibrous roots) as well as a bare soil control. Soil hydraulic properties such as near-saturated hydraulic conductivity, flow weighted pore radius, pore number and macroporosity are derived from measurements using a tension infiltrometer. The temporal dynamics are then analysed in terms of potential driving forces. Our results revealed significant temporal changes of hydraulic conductivity. When approaching saturation, spatial variability tended to dominate over the temporal evolution. Changes in near-saturated hydraulic conductivity were mainly a result of changing pore number, while the flow weighted mean pore radius showed less temporal dynamic in the no-till system. Macroporosity in the measured range of 0 to -10 cm pressure head ranged from 1.99e-4 to 8.96e-6 m3m-3. The different plant coverage revealed only minor influences on the observed system dynamics. Mustard increased slightly the flow weighted mean pore radius, being 0.090 mm in mustard compared to 0.085 mm in bare soil and 0.084 mm in rye. Still pore radius changes were of minor importance for the overall temporal dynamics. Rainfall was detected as major driving force of the temporal evolution of structural soil hydraulic properties at the site. Soil hydraulic conductivity in the slightly unsaturated range (-7 cm to -10 cm) showed a similar time course as a moving average of rainfall. Drying induced a decrease in conductivity while wetting of the soil resulted in higher conductivity values. Approaching saturation however, the drying phase showed a different behaviour with increasing values of hydraulic conductivity. This may be explained probably by formation of cracks acting as large macropores. We concluded that aggregate coalescence as a function of capillary forces and soil rheologic properties (cf. Or et al., 2002) are a main predictor of temporal dynamics of near saturated soil hydraulic properties while different plant covers only had a minor effect on the observed system dynamics. Or, D., Ghezzehei, T.A. 2002. Modeling post-tillage soil structural dynamics. a review. Soil Till Res. 64, 41-59.

Bodner, G.; Scholl, P.; Loiskandl, W.; Kaul, H.-P.

2012-04-01

27

Impact of land management on soil structure and soil hydraulic properties  

NASA Astrophysics Data System (ADS)

Study is focused on a comparison of a soil structure and soil hydraulic properties within soil profiles of a same soil type under different land management. Study was performed in Haplic Luvisol in Hnevceves the Czech Republic. Two soil profiles, which were in close distance from each other, were chosen: 1. under the conventional tillage, 2. under the permanent (30 years) grass cover. Soil sampling and field experiments were carried out immediately after the harvest of winter barley in 2008. The micromorphological images were used to evaluate the soil structure of all Ap, Bt1, Bt2 and C diagnostic horizons. The hydraulic properties of the diagnostic horizons were studied in the laboratory using multistep outflow experiments performed on the undisturbed 100-cm3 soil samples. A tension disc infiltrometer (with a disc radius of 10 cm) and minidisc tension infiltrometers (with a disc radius of 2.2 cm) were used to measure cumulative water infiltration under unsaturated conditions created using a pressure head of -2 cm. Measurements were performed at a depths of 5, 45, 75 and 110 cm, which corresponded to the Ap, Bt1, Bt2 and C horizons of studied Haplic Luvisol at both locations. The Guelph permeameter was used to measure cumulative water flux under surface ponding conditions. The depth of the drilled well was 10, 50, 80 and 115 cm, the well radius was 3 cm, and the well ponding depth was 5 cm. Both tests were used to evaluate hydraulic conductivity (K for h=-2cm, and Ks) values. Results showed, that while properties in the Bt2 and C horizons of both soil profiles were relatively similar, properties in the Ap and Bt1 horizons were different. The fraction of gravitational pores (which may cause preferential flow) in the Ap and Bt1 horizons of the soil profile under the convectional tillage was large than those in the Ap and Bt1 horizons of the soil profile under the permanent grass. This influenced for instance the Ks values measured using the Guelph permeametr. The Ks values were higher and more variable in the soil profile under the convectional tillage than those in the soil profile under the permanent grass. On the other hand, due to the periodical tillage and consequent soil structure breakdown, the fraction of the large capillary pores were smaller in the Ap horizon of the soil profile under the convectional tillage than that in the Ap horizon of the soil profile under the permanent grass. As result the K (h=-2cm) values measured using the tension infiltrometer in the soil profile under the permanent grass was higher than those in the soil profile under the convectional tillage. However, the fraction of the large capillary pores and K (h=-2cm) values were similar in the Bt1 horizons of both soil profiles. Thus the land management impacted both macropores and matrix pores in the Ap horizon and macropores (prismatic structure and biopores) in the Bt1 horizon. Acknowledgement: Authors acknowledge the financial support of the Grant Agency of the Czech Republic (grant No. GA CR 526/08/0434) and the Ministry of Education, Youth and Sports of the Czech Republic (grant No. MSM 6046070901).

Kodesova, Radka; Jirku, Veronika; Nikodem, Antonin; Muhlhanselova, Marcela; Zigova, Anna

2010-05-01

28

The Effect of Soil Hydraulic Properties vs. Soil Texture in Land Surface Models  

NASA Technical Reports Server (NTRS)

This study focuses on the effect of Soil Hydraulic Property (SHP) selection on modeled surface fluxes following a rain storm in a semi-arid environment. SHPs are often defined based on a Soil Texture Class (STC). To examine the effectiveness of this approach, the Noah land surface model was run with each of 1306 soils in a large SHP database. Within most STCs, the outputs have a range of 350 W/m2 for latent and sensible heat fluxes, and 8K for surface temperature. The average difference between STC median values is only 100 W/m2 for latent and sensible heat. It is concluded that STC explains 5-15% of the variance in model outputs and should not be used to determine SHPs.

Gutmann, E. D.; Small, E. E.

2005-01-01

29

SOIL HYDRAULIC PROPERTIES INFLUENCED BY CORN STOVER REMOVAL FROM NO-TILL CORN IN OHIO  

Technology Transfer Automated Retrieval System (TEKTRAN)

Corn (Zea mays L.) stover removal for biofuel production and other uses may alter soil hydraulic properties, but site-specific information needed to determine the threshold levels of removal for the U.S. Corn Belt region is limited. We quantified impacts of systematic removal of corn stover on soil ...

30

Upscaling of soil hydraulic properties for steady state evaporation and infiltration  

E-print Network

Upscaling of soil hydraulic properties for steady state evaporation and infiltration Jianting Zhu for steady state evaporation and infiltration. The specific objectives of this study are (1) to address evaporation and infiltration in unsaturated soil. Using an analytical solution of Richards' equation

Mohanty, Binayak P.

31

Dewatering and the hydraulic properties of soft, sulfidic, coastal clay soils  

NASA Astrophysics Data System (ADS)

Dewatering and consolidation of saturated swelling soils are governed by pressure-dependent soil hydraulic properties. Existing measurement techniques are difficult and slow. We illustrate a simple, rapid desorption technique, developed for industrial slurries, to measure hydraulic properties of a gel-like sulfidic, estuarine soil (˜70% water content). Measured hydraulic conductivities, K(?), were very small, ˜10-10 m/s, giving a representative capillary fringe thickness of ˜7 m and characteristic gravity drainage times around 40 years. Capillarity therefore dominates flow in these soils. Estimated times for dewatering this soil under surface loading with closely spaced, vertical wick drains, are 2 to 70 years, consistent with experience. A Netherlands marine clay soil, saturated with seawater, is unexpectedly wetter than the brackish estuarine soil here at the same matric potential, ?. However, K(?) for both soils overlap, suggesting the engineering approximation, K(?) ? ???-1, for marine-deposited clays. The functional dependencies of hydraulic properties surprisingly are not consistent with similar-media or double-layer theories.

White, Ian; Smiles, David E.; Santomartino, Silvana; van Oploo, Pam; MacDonald, Bennett C. T.; Waite, T. David

2003-10-01

32

Effects of spatial variability of soil hydraulic properties on water dynamics  

NASA Astrophysics Data System (ADS)

Soil hydraulic properties may present spatial variability and dependence at the scale of watersheds or fields even in man-made single soil structures, such as cranberry fields. The saturated hydraulic conductivity (Ksat) and soil moisture curves were measured at two depths for three cranberry fields (about 2 ha) at three different sites near Québec city, Canada. Two of the three studied fields indicate strong spatial dependence for Ksat values and soil moisture curves both in horizontal and vertical directions. In the summer of 2012, the three fields were equipped with 55 tensiometers installed at a depth of 0.10 m in a regular grid. About 20 mm of irrigation water were applied uniformly by aspersion to the fields, raising soil water content to near saturation condition. Soil water tension was measured once every hour during seven days. Geostatistical techniques such as co-kriging and cross-correlograms estimations were used to investigate the spatial dependence between variables. The results show that soil tension varied faster in high Ksat zones than in low Ksatones in the cranberry fields. These results indicate that soil water dynamic is strongly affected by the variability of saturated soil hydraulic conductivity, even in a supposed homogenous anthropogenic soil. This information may have a strong impact in irrigation management and subsurface drainage efficiency as well as other water conservation issues. Future work will involve 3D numerical modeling of the field water dynamics with HYDRUS software. The anticipated outcome will provide valuable information for the understanding of the effect of spatial variability of soil hydraulic properties on soil water dynamics and its relationship with crop production and water conservation.

Gumiere, Silvio Jose; Caron, Jean; Périard, Yann; Lafond, Jonathan

2013-04-01

33

Using the NRCS National Soils Information System (NASIS) to provide soil hydraulic properties for engineering applications  

Technology Transfer Automated Retrieval System (TEKTRAN)

Modern agricultural, biological, and environmental engineers have a multitude of uses for soil hydraulic parameters that quantify the ability of soils and sediments to retain and transmit water. These parameters are difficult and costly to obtain, especially if large areas of land need to be charac...

34

Variability and scaling of hydraulic properties for 200 Area soils, Hanford Site  

SciTech Connect

Over the years, data have been obtained on soil hydraulic properties at the Hanford Site. Much of these data have been obtained as part of recent site characterization activities for the Environmental Restoration Program. The existing data on vadose zone soil properties are, however, fragmented and documented in reports that have not been formally reviewed and released. This study helps to identify, compile, and interpret all available data for the principal soil types in the 200 Areas plateau. Information on particle-size distribution, moisture retention, and saturated hydraulic conductivity (K{sub s}) is available for 183 samples from 12 sites in the 200 Areas. Data on moisture retention and K{sub s} are corrected for gravel content. After the data are corrected and cataloged, hydraulic parameters are determined by fitting the van Genuchten soil-moisture retention model to the data. A nonlinear parameter estimation code, RETC, is used. The unsaturated hydraulic conductivity relationship can subsequently be predicted using the van Genuchten parameters, Mualem`s model, and laboratory-measured saturated hydraulic conductivity estimates. Alternatively, provided unsaturated conductivity measurements are available, the moisture retention curve-fitting parameters, Mualem`s model, and a single unsaturated conductivity measurement can be used to predict unsaturated conductivities for the desired range of field moisture regime.

Khaleel, R.; Freeman, E.J.

1995-10-01

35

Bayesian inverse modelling of in situ soil water dynamics: using prior information about the soil hydraulic properties  

NASA Astrophysics Data System (ADS)

In situ observations of soil water state variables under natural boundary conditions are often used to estimate field-scale soil hydraulic properties. However, many contributions to the soil hydrological literature have demonstrated that the information content of such data is insufficient to reliably estimate all the soil hydraulic parameters. In this case study, we tested whether prior information about the soil hydraulic properties could help improve the identifiability of the van Genuchten-Mualem (VGM) parameters. Three different prior distributions with increasing complexity were formulated using the ROSETTA pedotransfer function (PTF) with input data that constitutes basic soil information and is readily available in most vadose zone studies. The inverse problem was posed in a formal Bayesian framework and solved using Markov chain Monte Carlo (MCMC) simulation with the DiffeRential Evolution Adaptive Metropolis (DREAM) algorithm. Synthetic and real-world soil water content data were used to illustrate our approach. The results of this study corroborate and explicate findings previously reported in the literature. Indeed, soil water content data alone contained insufficient information to reasonably constrain all VGM parameters. The identifiability of these soil hydraulic parameters was substantially improved when an informative prior distribution was used with detailed knowledge of the correlation structure among the respective VGM parameters. A biased prior did not distort the results, which inspires confidence in the robustness and effectiveness of the presented method. The Bayesian framework presented in this study can be applied to a wide range of vadose zone studies and provides a blueprint for the use of prior information in inverse modelling of soil hydraulic properties at various spatial scales.

Scharnagl, B.; Vrugt, J. A.; Vereecken, H.; Herbst, M.

2011-02-01

36

Estimation of effective soil hydraulic properties at field scale via ground albedo neutron sensing  

NASA Astrophysics Data System (ADS)

Upscaling of soil hydraulic parameters is a big challenge in hydrological research, especially in model applications of water and solute transport processes. In this contest, numerous attempts have been made to optimize soil hydraulic properties using observations of state variables such as soil moisture. However, in most of the cases the observations are limited at the point-scale and then transferred to the model scale. In this way inherent small-scale soil heterogeneities and non-linearity of dominate processes introduce sources of error that can produce significant misinterpretation of hydrological scenarios and unrealistic predictions. On the other hand, remote-sensed soil moisture over large areas is also a new promising approach to derive effective soil hydraulic properties over its observation footprint, but it is still limited to the soil surface. In this study we present a new methodology to derive soil moisture at the intermediate scale between point-scale observations and estimations at the remote-sensed scale. The data are then used for the estimation of effective soil hydraulic parameters. In particular, ground albedo neutron sensing (GANS) was used to derive non-invasive soil water content in a footprint of ca. 600 m diameter and a depth of few decimeters. This approach is based on the crucial role of hydrogen compared to other landscape materials as neutron moderator. As natural neutron measured aboveground depends on soil water content, the vertical footprint of the GANS method, i.e. its penetration depth, does also. Firstly, this study was designed to evaluate the dynamics of GANS vertical footprint and derive a mathematical model for its prediction. To test GANS-soil moisture and its penetration depth, it was accompanied by other soil moisture measurements (FDR) located at 5, 20 and 40 cm depths over the GANS horizontal footprint in a sunflower field (Brandenburg, Germany). Secondly, a HYDRUS-1D model was set up with monitored values of crop height and meteorological variables as input during a four-month period. Parameter estimation (PEST) software was coupled to HYDRUS-1D in order to calibrate soil hydraulic properties based on soil water content data. Thirdly, effective soil hydraulic properties were derived from GANS-soil moisture. Our observations show the potential of GANS to compensate the lack of information at the intermediate scale, soil water content estimation and effective soil properties. Despite measurement volumes, GANS-derived soil water content compared quantitatively to FDRs at several depths. For one-hour estimations, root mean square error was estimated as 0.019, 0.029 and 0.036 m3/m3 for 5 cm, 20 cm and 40 cm depths, respectively. In the context of soil hydraulic properties, this first application of GANS method succeed and its estimations were comparable to those derived by other approaches.

Rivera Villarreyes, C. A.; Baroni, G.; Oswald, S. E.

2012-04-01

37

LANDSCAPE AND CONSERVATION MANAGEMENT EFFECTS ON SOIL HYDRAULIC PROPERTIES FOR AN EPIAQUALF  

Technology Transfer Automated Retrieval System (TEKTRAN)

Tillage and conservation management systems have been developed to reduce the environmental impacts of crop production systems, and have been reported to influence soil hydraulic properties. However, the effects of landscape positions and their interaction with management systems have received less ...

38

Quantitative Metrics of Soil Structure and Relationships to Hydraulic Properties in a Vertic Argiudoll  

E-print Network

to soil hydraulic parameters, especially saturated hydraulic conductivity (Ks) and water retention curve (WRC) parameters. Soil moisture data collected at the lysimeter, in conjunction with atmospheric data from an adjacent tower, were used as inputs...

Eck, Dennis V.

2014-05-31

39

SOIL HYDRAULIC AND ELECTRICAL PROPERTIES FOR DIFFERENT SOILS, SLOPES, AND CROP ROTATIONS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Crop management can alter soil physical properties, but variability of these properties may mask treatment effects. The purpose of this study was to compare soil physical property variation under two crop rotations, and to examine interrelations among different soil physical properties. A six-year r...

40

Assessing agricultural management effects on structure related soil hydraulic properties by tension infiltrometry  

NASA Astrophysics Data System (ADS)

Soil structure is a dynamic property subject to numerous natural and human influences. It is recognized as fundamental for sustainable functioning of soil. Therefore knowledge of management impacts on the sensitive structural states of soil is decisive in order to avoid soil degradation. The stabilization of the soil's (macro)pore system and eventually the improvement of its infiltrability are essential to avoid runoff and soil erosion, particularly in view of an increasing probability of intense rainfall events. However structure-related soil properties generally have a high natural spatiotemporal variability that interacts with the potential influence of agricultural land use. This complicates a clear determination of management vs. environmental effects and requires adequate measurement methods, allowing a sufficient spatiotemporal resolution to estimate the impact of the targeted management factors within the natural dynamics of soil structure. A common method to assess structure-related soil hydraulic properties is tension infiltrometry. A major advantage of tension infiltrometer measurements is that no or only minimum soil disturbance is necessary and several structure-controlled water transmission properties can readily be derived. The method is more time- and cost-efficient compared to laboratory measurements of soil hydraulic properties, thus enabling more replications. Furthermore in situ measurements of hydraulic properties generally allow a more accurate reproduction of field soil water dynamics. The present study analyses the impact of two common agricultural management options on structure related hydraulic properties based on tension infiltrometer measurements. Its focus is the identification of the role of management within the natural spatiotemporal variability, particularly in respect to seasonal temporal dynamics. Two management approaches are analysed, (i) cover cropping as a "plant-based" agro-environmental measure, and (ii) tillage with different intensities including conventional tillage with a mouldboard plough, reduced tillage with a chisel plough and no-tillage. The results showed that the plant-based management measure of cover cropping had only minor influence on near-saturated hydraulic conductivity (kh) and flow weighted mean pore radius (?m). Substantial over-winter changes were found with a significant increase in kh and a reduction in the pore radius. A spatial trend in soil texture along the cover cropped slope resulted in a higher kh at lower pressure heads at the summit with higher fractions of coarse particles, while kh tended to be highest at the toeslope towards saturation. Cover crop management accounted for a maximum of 9.7% of the total variability in kh, with a decreasing impact towards the unsaturated range. A substantial difference to bare soil in the cover cropped treatments could be identified in relation to a stabilization of macro-pores over winter. The different tillage treatments had a substantial impact on near-saturated kh and pore radius. Although conventional tillage showed the highest values in kh and ?m, settling of the soil after the ploughing event tended to reduce differences over time compared to the other tillage methods. The long-term no-tillage (10 years) however had the lowest values of kh at all measurement dates. The high contents of silt and fine sand probably resulted in soil densification that was not counterbalanced sufficiently by biological structure forming agents. The study could show that soil structure related hydraulic properties are subject to a substantial seasonal variability. A comprehensive assessment of agricultural measures such as tillage or cover cropping requires an estimate of these temporal dynamics and their interaction with the management strategies. Particularly for plant-based management measures such as cover cropping, which represent a less intense intervention in the structural states of the soil compared to tillage, this was evident, as the main mechanism revealed for this measure was structure stabilization over

Bodner, G.; Loiskandl, W.; Kaul, H.-P.

2009-04-01

41

ReproducedfromVadoseZoneJournal.PublishedbySoilScienceSocietyofAmerica.Allcopyrightsreserved. Hydraulic Properties of a Desert Soil Chronosequence in the Mojave Desert, USA  

E-print Network

VadoseZoneJournal.PublishedbySoilScienceSocietyofAmerica.Allcopyrightsreserved. Hydraulic Properties of a Desert Soil Chronosequence in the Mojave Desert, USA M. H. Young,* E. V. Mc), fine-grained, gravel-poor, vesicular A (Av) soil horizon.1 Desert pave-Desert pavements are prominent's equation and inverse modeling for consideration in development of desert pavements, es-evaluating hydraulic

Ahmad, Sajjad

42

Multiobjective Optimization of Effective Soil Hydraulic Properties on a Lysimeter from a Layered, Gravelly Vadose Zone  

NASA Astrophysics Data System (ADS)

Estimation of effective soil hydraulic parameters for characterization of the vadose zone properties is important for many applications from prediction of solute and pesticide transport to water balance modeling in small catchments. Inverse modeling has become a common approach to infer the parameters of the water retention and hydraulic conductivity functions from dynamic experiments under varying boundary conditions. To gain further inside into to the water transport behavior of an agricultural field site with a layered, gravelly vadose zone, a lysimeter was taken and equipped with a total of 48 sensors (24 tensiometers and 24 water content probes). The sensors were arranged in 6 vertical arrays consisting of 4 sensor pairs, respectively. Pressure heads and water contents were measured in four depths in each of the arrays allowing for the estimation of the soil hydraulic properties of the three individual soil layers by inverse modeling. For each of the soil horizons, a separate objective function was defined to fit the model to the observation. We used the global multiobjective multimethod search algorithm AMALGAM (Vrugt et al., 2007) in combination with the water flow and solute transport model Hydrus1D (Šimúnek et al., 2008) to estimate the soil hydraulic properties of the Mualem van Genuchten model (van Genuchten, 1980). This experimental design served for the investigation of two important questions: a) do effective soil hydraulic properties at the lysimeter scale exist, more specifically: can a single representative parameter set be found which describes the hydraulic behavior in each of the arrays with acceptable performance? And b) which degree of freedom is necessary or required for an accurate description of the one dimensional water flow at each of the arrays? Effective soil hydraulic parameters were obtained for each of the sensor arrays individually, resulting in good agreement between the model predictions and the observations for the individual soil horizons. However, no general parameter set could be identified to describe the integral water flow over all arrays with acceptable performance due to the high degree of horizontal heterogeneity within the soil horizons. Furthermore it is shown that some of the hydraulic parameters are well defined, while others are associated with high uncertainties, e.g. the saturated hydraulic conductivity and the residual water content. van Genuchten, M. Th., 1980: A closed form equation for predicting the hydraulic conductivity of unsaturated soils. Soil Science Society of America Journal, 44, 892-898. Šimúnek, J., Šejna, M., Saito, H., Sakai, M. & van Genuchten, M. Th., 2008: The Hydrus-1D Software Package for Simulating the Movement of Water, Heat, and Multiple Solutes in Variably Saturated Media, Version 4.0, HYDRUS Software Series 3, Department of Environmental Sciences, University of California Riverside, Riverside, California, USA, pp. 315. Vrugt, J.A. and Robinson, B.A. 2007: Improved evolutionary optimization from genetically adaptive multimethod search, Proc. Nat. Acad. Sci. USA, 104, 708 - 711.

Werisch, Stefan; Lennartz, Franz

2013-04-01

43

Modeling the impacts of soil hydraulic properties on temporal stability of soil moisture under a semi-arid climate  

NASA Astrophysics Data System (ADS)

Despite the significant spatiotemporal variability of soil moisture, the phenomenon of temporal stability of soil moisture (TS SM) has been widely observed in field studies. However, the lack of understandings of the factors that control TS SM has led to some contradictory findings about TS SM. To resolve this issue, numerical models may offer an alternative way to complement field studies by quantifying different controls on TS SM. In this study, a 1-D vadose zone model was adopted to simulate daily soil moisture contents, which were used to compute the mean relative difference (MRD) and standard deviation of relative difference (SDRD) of soil moisture. Different from recent modeling studies, a soil dataset was employed with 200 samples of correlated soil hydraulic parameters for sandy soils. Compared to the results of previous modeling studies, more reasonable patterns of MRD and SDRD that resembled field observations were produced. By varying soil hydraulic parameter values, different patterns of MRD and SDRD could also be generated, implying variations in soil hydraulic properties could partly control the patterns of MRD and SDRD. More specifically, the residual soil moisture content (?r) was found to be the primary control on MRD, mainly due to the semi-arid climate that was simulated. By fixing ?r, however, a highly nonlinear relationship emerged between MRD and the shape factor n in the van Genuchten model, which resulted in the positively skewed distributions of MRD widely observed for sandy soils in field experiments. Moreover, both the range and skewness of the distributions of MRD were affected by the range of n. In addition, with increasing n, a positive correlation between MRD and the shape factor l in the van Genuchten model was also found. The simulation results suggested that the control of soil hydraulic properties on MRD might weaken for areas under bare surface conditions or for regions with more humid climates due to elevated soil moisture contents. Therefore, the impacts of soil hydraulic properties on TS SM may vary under different climate regimes.

Wang, Tiejun

2014-11-01

44

Laboratory evaporation experiments in undisturbed peat columns for determining peat soil hydraulic properties  

NASA Astrophysics Data System (ADS)

Knowledge about hydraulic properties of organic soils is crucial for the interpretation of the hydrological situation in peatlands. This in turn is the basis for designing optimal rewetting strategies, for assessing the current and future climatic water balance and for quantifying greenhouse gas emissions of CO2, CH4 and N2O, which are strongly controlled by the depth of the peat water table. In contrast to mineral soils, the hydraulic properties of organic soils differ in several aspects. Due to the high amount of organic components, strong heterogeneity, and shrinkage and swelling of peat, accompanied by changing soil volume and bulk density, the applicability of standard hydraulic functions developed for mineral soils for describing peat soil moisture dynamics is often questioned. Hence, the objective of this study was to investigate the applicability of the commonly applied van Genuchten-Mualem (VGM) parameterization and to evaluate model errors for various peat types. Laboratory column experiments with undisturbed peat soils (diameter: 30 cm, height: 20 cm) from 5 different peatlands in Germany were conducted. In numerical simulations using HYDRUS-1D the experimental data were used for an inverse estimation of the soil hydraulic parameters. Using the VGM parameterization, the model errors between observed and measured pressure heads were quantified with a root mean square error (RMSE) of 20 - 65 cm. The RMSE increased for soils with higher organic carbon content and higher porosity. Optimizing the VGM 'tortuosity' parameter (?) instead of fixing it to its default of 0.5 strongly reduced the RMSE, especially for the soils that showed high pressure head gradients during the experiment. Due to the fact, that very negative pressure heads in peatlands occur rarely, we reduced the range of pressured heads in the inversion to a 'field-relevant' range from 0 to -200 cm which strongly reduced the RMSE to 6 - 12 cm and makes the VGM parameterization applicable for all investigated peat soils. For the field-relevant scale, especially for very wet conditions, we demonstrate the importance of macro-pores by using a simple macro-pore approach, with only 1 additional parameter, i.e. the macro-pore fraction, which strongly reduced the RMSE down to 1 - 7 cm. Since ? has not been identified as an important parameter for the field-relevant range, only 5 parameters were optimized in this approach. This keeps the derivation of the parameters manageable and thus provides a model that is applicable to practical issues.

Dettmann, U.; Frahm, E.; Bechtold, M.

2013-12-01

45

Linking hydraulic properties of fire-affected soils to infiltration and water repellency  

USGS Publications Warehouse

Heat from wildfires can produce a two-layer system composed of extremely dry soil covered by a layer of ash, which when subjected to rainfall, may produce extreme floods. To understand the soil physics controlling runoff for these initial conditions, we used a small, portable disk infiltrometer to measure two hydraulic properties: (1) near-saturated hydraulic conductivity, Kf and (2) sorptivity, S(??i), as a function of initial soil moisture content, ??i, ranging from extremely dry conditions (??i < 0.02 cm3 cm-3) to near saturation. In the field and in the laboratory replicate measurements were made of ash, reference soils, soils unaffected by fire, and fire-affected soils. Each has a different degrees of water repellency that influences Kf and S(??i). Values of Kf ranged from 4.5 ?? 10-3 to 53 ?? 10-3 cm s-1 for ash; from 0.93 ?? 10-3 to 130 ?? 10-3 cm s-1 for reference soils; and from 0.86 ?? 10-3 to 3.0 ?? 10-3 cm s-1, for soil unaffected by fire, which had the lowest values of Kf. Measurements indicated that S(??i) could be represented by an empirical non-linear function of ??i with a sorptivity maximum of 0.18-0.20 cm s-0.5, between 0.03 and 0.08 cm3 cm-3. This functional form differs from the monotonically decreasing non-linear functions often used to represent S(??i) for rainfall-runoff modeling. The sorptivity maximum may represent the combined effects of gravity, capillarity, and adsorption in a transitional domain corresponding to extremely dry soil, and moreover, it may explain the observed non-linear behavior, and the critical soil-moisture threshold of water repellent soils. Laboratory measurements of Kf and S(??i) are the first for ash and fire-affected soil, but additional measurements are needed of these hydraulic properties for in situ fire-affected soils. They provide insight into water repellency behavior and infiltration under extremely dry conditions. Most importantly, they indicate how existing rainfall-runoff models can be modified to accommodate a possible two-layer system in extremely dry conditions. These modified models can be used to predict floods from burned watersheds under these initial conditions.

Moody, J.A.; Kinner, D.A.; Ubeda, X.

2009-01-01

46

Effects of long-term irrigation with treated wastewater on the hydraulic properties of a clayey soil  

NASA Astrophysics Data System (ADS)

The increasing demand for freshwater (FW) for domestic use turns treated wastewater (WW) into an attractive source of water for irrigated agriculture. The main goal of this study was to evaluate the impact of 15 yrs of irrigation with WW on hydraulic properties and flow processes in a clayey soil, compared to FW use. It also quantitatively addressed the distribution with depth along the soil profile of that impact on soil hydraulic properties. Standard methods used in soil physics at the laboratory scale, and numerical solutions of the flow equations on the basis of HYDRUS, were applied to define fundamental soil hydraulic properties of disturbed soil samples from 0-20, 20-40, and 40-60 cm layers in the root zone. Results showed that saturated hydraulic conductivity, sorptivity, and infiltration rates are consistently lower in the WW irrigated soil samples at all depths. Water retention and hydraulic conductivity functions were affected by the use of WW, leading to a smaller, simulated-wetted volume below a dripper for the WW-irrigated soil case. These results illustrate the combined and complex effect of WW use on soil-exchangeable sodium percentage, and suggest changes in contact angle and pore size distribution. They also suggest that WW application will affect differently different zones in the soil profile, depending on irrigation management parameters and plant uptake characteristics.

Assouline, S.; Narkis, K.

2011-08-01

47

Measurement of Physical and Hydraulic Properties of Organic Soil Using Computed Tomographic Imagery  

NASA Astrophysics Data System (ADS)

The Lower Liard River valley is located within the continental northern boreal region and the zone of discontinuous permafrost. Lying in the centre of the Mackenzie basin, this valley is an extensive flat headwater region with a high density of open water and peatlands. Several standard methods of measuring the physical properties of organic soils exist, although many of them have several drawbacks that limit their use. Organic soils, in particular, have unique properties that require special attention to ensure that the measured hydrological characteristics are represented as they exist in nature. The goal of this research was to devise an improved method of analyzing and measuring the physical and hydraulic properties of organic soil using MicroCT imagery. Specifically, this research seeks to determine if two and three-dimensional images of peat can be used to accurately characterize air-filled porosity, active porosity, pore size distribution, pore saturated area and capillarity of porous Sphagnum cells. Results indicate that measurements derived from these images are consistent with current literature. They also suggest that this non-destructive method is a valuable tool for measuring peat physical and hydraulic properties and that there is potential for additional research using CT technology.

Blais, K. E.; Quinton, W. L.; Heck, R. J.; Price, J. S.; Schmidt, M. G.

2005-12-01

48

Wastewater effects on montmorillonite suspensions and hydraulic properties of sandy soils  

SciTech Connect

Recycled wastewater effluent is an important source of irrigation water in arid and semiarid regions. In these regions, however, irrigation water quality is one of the main factors limiting plant growth. Wastewater effluents generally contain high concentrations of suspended and dissolved solids, both organic and inorganic. Inorganic dissolved solids are only minimally removed from the effluent during conventional sewage treatment. As a result, most of the salts added during domestic and industrial usage remain in the irrigation water and may eventually reach the soil. A number of researchers have reported reduced hydraulic conductivity for soils to which treated wastewater has been applied. In this research, the influence of dissolved organic matter (DOM) contained in reclaimed wastewater effluents on the flocculation of montmorillonite and on the hydraulic properties of soils was studied. Flocculation values (FVs) for Na-montmorillonite increased with increasing concentrations of DOM at all pH levels analyzed. Maximum FV levels were exhibited for Na-montmorillonite at the highest DOM concentrations. The effect of DOM on FV can be explained by the mechanisms of edge-charge reversal and mutual flocculation. The hydraulic conductivity (HC) of a sandy soil was determined in the laboratory by leaching columns with an electrolyte solution chemically similar to that of the wastewater effluent (but without DOM). In columns treated with wastewater effluent, the HC exhibited a sharp decrease to only 20% of its initial value. The adverse effect of DOM on HC was evident for this soil despite a relatively low exchangeable sodium percentage (ESP). The reduction in HC is likely to be the result of decreases soil pore-size, which reflects two processes: (1) retention of part of the DOM during water percolation; and (2) a change in pore-size distribution due to swelling and dispersion of clay particles. The latter may result from a higher percentage of adsorbed sodium combined with the presence of humic substances from the wastewater effluent.

Tarchitzky, J.; Golobati, Y.; Keren, R.; Chen, Y.

1999-06-01

49

Estimating unsaturated soil hydraulic properties from laboratory tension disc infiltrometer experiments  

NASA Astrophysics Data System (ADS)

Four tension disc infiltration experiments were carried out on a loamy soil in the laboratory for the purpose of estimating the unsaturated soil hydraulic properties. Sixteen tensiometers were installed in pairs at the following coordinate (r,z) positions: (10, 2.5), (10, 5), (10, 10), (15, 5), (15, 10), (15, 15), (15, 20), and (15, 30), where r represents the distance from the axis of symmetry and z is the location below the soil surface. A time domain reflectometry (TDR) probe was used to measure water contents at a depth of 2 cm directly below the tension disc. The first three experiments involved supply pressure heads at the disc of -20, -10, -5, and -1 cm, with the experiment lasting for ~5 hours. The same supply pressure heads were also used for the fourth experiment, which lasted 6.25 days so as to reach steady state at each applied tension. The measured data were analyzed using Wooding's [1968] analytical solution and by numerical inversion. The parameter estimation method combined a quasi three-dimensional numerical solution of the Richards equation with the Marquardt-Levenberg optimization scheme. The objective function for the parameter estimation analysis was defined using different combinations of the cumulative infiltrated volume, TDR readings, and tensiometer measurements. The estimated hydraulic properties were compared against results obtained with an evaporation experiment as analyzed with Wind's [1968] method. Water contents in the retention curves were underestimated when both transient and quasi steady state experiments were analyzed by parameter estimation. Unsaturated hydraulic conductivities obtained by parameter estimation and using Wooding's [1968] analysis corresponded well. Drying branches of the hydraulic conductivity function determined by parameter estimation also corresponded well with those obtained with the evaporation method.

Šim?nek, Ji?í; Wendroth, Ole; van Genuchten, Martinus T.

1999-10-01

50

Changes in soil hydraulic properties caused by construction of a simulated waste trench at the Idaho National Engineering Laboratory, Idaho  

USGS Publications Warehouse

In order to assess the effect of filled waste disposal trenches on transport-governing soil properties, comparisons were made between profiles of undisturbed soil and disturbed soil in a simulated waste trench. The changes in soil properties induced by the construction of a simulated waste trench were measured near the Radioactive Waste Management Complex at the Idaho National Engineering Laboratory (INEL) in the semi-arid southeast region of Idaho. The soil samples were collected, using a hydraulically- driven sampler to minimize sample disruption, from both a simulated waste trench and an undisturbed area nearby. Results show that the undisturbed profile has distinct layers whose properties differ significantly, whereas the soil profile in the simulated waste trench is. by comparison, homogeneous. Porosity was increased in the disturbed cores, and, correspondingly, saturated hydraulic conductivities were on average three times higher. With higher soil-moisture contents (greater than 0.32), unsaturated hydraulic conductivities for the undisturbed cores were typically greater than those for the disturbed cores. With lower moisture contents, most of the disturbed cores had greater hydraulic conductivities. The observed differences in hydraulic conductivities are interpreted and discussed as changes in the soil pore geometry.

Shakofsky, S.M.

1995-01-01

51

Impact of anthropomorphic soil genesis on hydraulic properties: the case of cranberry production  

NASA Astrophysics Data System (ADS)

The construction of a cranberry field requires the installation of a drainage system which causes anthropic layering of the natural sequence of soil strata. Over the years, the soil hydraulic properties may change under the influence of irrigation and water table control. In fact, natural consolidation (drainage and recharge cycles), filtration and clogging soil pores by colloidal particle accelerated by water management will alter the hydrodynamic behavior of the soil (Gaillard et al., 2007; Wildenschild and Sheppard, 2013; Bodner et al., 2013). Today, advances in the field of tomography imagery allows the study a number of physicals processes of soils (Wildenschilds and Sheppard, 2013) especially for the transport of colloidal particles (Gaillard et al., 2007) and consolidation (Reed et al, 2006; Pires et al, 2007). Therefore, the main objective of this work is to analyze the temporal evolution of hydrodynamic properties of a sandy soil during repeated drainage and recharge cycles using a medical CT-scan. A soil columns laboratory experiment was setup in fall 2013, pressure head, input and output flow, tracer monitoring (KBr and ZrO2) and tomographic analyses have been used to quantify the temporal variation of the soil hydrodynamic properties of these soil columns. The results showed that the water management (irrigation and drainage) has strong effect on soil genesis and causes significant alteration of soil hydraulic properties, which may reduce soil drainage capacity. Knowledge about the mechanisms responsible of anthropic cranberry soil genesis will allow us to predict soil evolution according to several conditions (soil type, drainage system design, water management) to better anticipate and control their future negative effects on cranberry production. References: Bodner, G., P. Scholl and H.P. Kaul. 2013. Field quantification of wetting-drying cycles to predict temporal changes of soil pore size distribution. Soil and Tillage Research 133: 1-9. doi:http://dx.doi.org/10.1016/j.still.2013.05.006. Gaillard, J.-F., C. Chen, S.H. Stonedahl, B.L.T. Lau, D.T. Keane and A.I. Packman. 2007. Imaging of colloidal deposits in granular porous media by X-ray difference micro-tomography. Geophysical Research Letters 34: L18404. doi:10.1029/2007GL030514. Pires, L.F., O.O.S. Bacchi and K. Reichardt. 2007. Assessment of soil structure repair due to wetting and drying cycles through 2D tomographic image analysis. Soil and Tillage Research 94: 537-545. doi:http://dx.doi.org/10.1016/j.still.2006.10.008. Reed, A. H., Thompson, K. E., Zhang, W., Willson, C. S., & Briggs, K. B. (2006). Quantifying consolidation and reordering in natural granular media from computed tomography images. Advances in X-ray Tomography for Geomaterials, 263-268. Wildenschild, D. and A.P. Sheppard. 2013. X-ray imaging and analysis techniques for quantifying pore-scale structure and processes in subsurface porous medium systems. Advances in Water Resources 51: 217-246. doi:http://dx.doi.org/10.1016/j.advwatres.2012.07.018.

Periard, Yann; José Gumiere, Silvio; Rousseau, Alain N.; Caron, Jean; Hallema, Dennis W.

2014-05-01

52

Use of LANDSAT images of vegetation cover to estimate effective hydraulic properties of soils  

NASA Technical Reports Server (NTRS)

The estimation of the spatially variable surface moisture and heat fluxes of natural, semivegetated landscapes is difficult due to the highly random nature of the vegetation (e.g., plant species, density, and stress) and the soil (e.g., moisture content, and soil hydraulic conductivity). The solution to that problem lies, in part, in the use of satellite remotely sensed data, and in the preparation of those data in terms of the physical properties of the plant and soil. The work was focused on the development and testing of a stochastic geometric canopy-soil reflectance model, which can be applied to the physically-based interpretation of LANDSAT images. The model conceptualizes the landscape as a stochastic surface with bulk plant and soil reflective properties. The model is particularly suited for regional scale investigations where the quantification of the bulk landscape properties, such as fractional vegetation cover, is important on a pixel by pixel basis. A summary of the theoretical analysis and the preliminary testing of the model with actual aerial radiometric data is provided.

Eagleson, Peter S.; Jasinski, Michael F.

1988-01-01

53

Estimation of soil hydraulic properties using hydrologic trajectories in transient GPR data  

NASA Astrophysics Data System (ADS)

Ground penetrating radar has been used extensively in the past to image soil structure and moisture distributions. Well established tools, such as normal moveout corrections, have been established to assist in interpreting this data. Recently there has been growing interest in also using surface-based reflection GPR to monitor transient infiltration events. However, there is somewhat limited experience and tools available to assist in the interpretation of this data, particularly for studies that make use of commonly available commercial GPR systems. In this work we use the concept of hydraulic trajectories expressed as patterns obtained in GPR data through time to investigate dynamic soil processes. Using both numerical studies and a variable rate infiltration experiment conducted in a sand box, we show that different soil processes create distinctive patterns in the transient GPR data. We then illustrate how coherency analysis based on semblance in the radar data can be used to estimate soil hydraulic properties when coupled with the unsaturated flow model HYDRUS-1D. Based on data from the sand box experiment we found that the approach is able to capture many of the key parameters in the Mualem-vanGenuchten model for the hydraulic properties of soils. We also found that the GPR data appear to be sensitive to field-scale issues, such air entrapment in the soil, which are not represented in core scale studies of soil processes. A key advantage of the coherency approach to analyzing the data is that the calculation of semblance is highly computationally efficient. As a result it can be applied to large, multi-offset GPR datasets. To test this idea we have developed an automated GPR collection system to generate transient multioffset data during infiltration experiments in the sand box. The data shows consistent patterns through time at all offsets. Additional features, such as variations in amplitude are also apparent in the data. We suggest that collection of transient multi-offset data will provide significantly more information on soil processes compared to transient single offset or static multi-offset surveys alone.

Moysey, S. M.; Mangel, A. R.

2010-12-01

54

A Comparison of Land Surface Model Soil Hydraulic Properties Estimated by Inverse Modeling and Pedotransfer Functions  

NASA Technical Reports Server (NTRS)

Soil hydraulic properties (SHPs) regulate the movement of water in the soil. This in turn plays an important role in the water and energy cycles at the land surface. At present, SHPS are commonly defined by a simple pedotransfer function from soil texture class, but SHPs vary more within a texture class than between classes. To examine the impact of using soil texture class to predict SHPS, we run the Noah land surface model for a wide variety of measured SHPs. We find that across a range of vegetation cover (5 - 80% cover) and climates (250 - 900 mm mean annual precipitation), soil texture class only explains 5% of the variance expected from the real distribution of SHPs. We then show that modifying SHPs can drastically improve model performance. We compare two methods of estimating SHPs: (1) inverse method, and (2) soil texture class. Compared to texture class, inverse modeling reduces errors between measured and modeled latent heat flux from 88 to 28 w/m(exp 2). Additionally we find that with increasing vegetation cover the importance of SHPs decreases and that the van Genuchten m parameter becomes less important, while the saturated conductivity becomes more important.

Gutmann, Ethan D.; Small, Eric E.

2007-01-01

55

An evaporation test based on Thermal Infra Red Remote-Sensing to select appropriate soil hydraulic properties  

E-print Network

on the physical link between the soil water diffusion properties and the plant water stress, which has been named properties 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 Gilles Boulet1 to estimate common soil hydraulic properties at regional scale. Since they rely on an empirical link between

Paris-Sud XI, Université de

56

Deep rooting plants influence on soil hydraulic properties and air conductivity over time  

NASA Astrophysics Data System (ADS)

Crop sequences are commonly suggested as an alternative to improve subsoil structure. A well structured soil can be characterized by enhanced transport properties. Our main hypothesis was, that different root systems can modify the soil's macro/mesopore network if enough cultivation time is given. We analyzed the influence of three crops with either shallower roots (Festuca arundinacea, fescue) or taproots (Cichorium intybus, chicory and Medicago sativa, alfalfa). The crops where cultivated on a Haplic Luvisol near Bonn (Germany) for one, two or three years. Undisturbed soil cores were taken for measurement of unsaturated hydraulic conductivity and air permeability. The unsaturated conductivity was measured using the evaporation method, monitoring the water content and tension at two depths of each undisturbed soil core. The van Genuchten-Mualem model (1991) was fitted to the measured data. Air permeability was measured in a permeameter with constant flow at low pressure gradient. The measurements were repeated at -1, -3, -6, -15, -30 and -50 kPa matric tension and the model of Ball et al. (1988) was used to describe permeability as function of matric tension. Furthermore, the cores equilibrated at -15 kPa matric tension were scanned with X-Ray computer tomography. By means of 3D image analysis, geometrical features as pore size distribution, tortuosity and connectivity of the pore network was analyzed. The measurements showed an increased unsaturated hydraulic conductivity associated to coarser pores at the taprooted cultivations. A enhanced pore system (related to shrink-swell processes) under alfalfa was observed in both transport measurements and was confirmed by the 3D image analysis. This highly functional pore system (consisting mainly of root paths, earthworm channels and shrinking cracks) was clearly visible below the 75 cm of depth and differentiated significantly from the other two treatments only after three years of cultivation, which shows the time needed to modify soil structure under these conditions.

Uteau, Daniel; Peth, Stephan; Diercks, Charlotte; Pagenkemper, Sebastian; Horn, Rainer

2014-05-01

57

An easily installable groundwater lysimeter to determine water balance components and hydraulic properties of peat soils Hydrology and Earth System Sciences, 7(1), 2332 (2003) EGU  

E-print Network

installable groundwater lysimeter to determine water balance components and hydraulic properties of peat soils. Moreover, they should allow the in situ determination of the hydraulic properties (water retentionAn easily installable groundwater lysimeter to determine water balance components and hydraulic

Boyer, Edmond

58

PHYSICAL AND HYDRAULIC PROPERTIES OF ENGINEERED SOIL MEDIA FOR BIORETENTION BASINS  

Microsoft Academic Search

The composition of engineered soil media largely determines the stormwater treatment efficiency of urban bioretention basins. Laboratory flow-through experiments were conducted to quantify infiltration, bulk density, and moisture holding capacity as a function of different composite mixtures of sand, soil, and compost, and to assess the effect of compaction on bulk density, moisture holding capacity, and saturated hydraulic conductivity. Eleven

A. M. Thompson; A. C. Paul; N. J. Balster

59

An Analysis of the Impacts of Sodic Soil Amelioration on Soil Hydraulic Properties, Deep Drainage and Groundwater Using the HYDRUS Model  

NASA Astrophysics Data System (ADS)

Groundwater tables are rising beneath irrigated fields in some areas of the lower Burdekin in North Queensland, Australia. The soils where this occurs are predominantly sodic clay soils with low hydraulic conductivities. Many of these soils have been treated by applying gypsum or by increasing the salinity of irrigation water by mixing saline groundwater with fresh river water. While the purpose of these treatments is to increase infiltration into the surface soils and improve productivity of the root zone, the treatments appear to have altered the soil hydraulic properties well below the root zone leading to increased groundwater recharge and rising water tables. In this paper we discuss application of the HYDRUS model with major ion reaction and transport and soil water chemistry-dependent hydraulic conductivity to assess the likely depth, magnitude and timing of the impacts of surface soil amelioration on soil hydraulic properties below the root zone and hence groundwater recharge. We highlight in particular the role of those factors which might influence the impacts of the soil treatment, particularly at depth, including the large amounts of rain during the relatively short wet season and the presence of thick low permeability clay layers.

Reading, L.; Lockington, D. A.; Bristow, K. L.; Baumgartl, T.

2009-12-01

60

Influence of metal ions and pH on the hydraulic properties of potential acid sulfate soils  

NASA Astrophysics Data System (ADS)

SummaryAcid sulfate soils (ASS) cover extensive areas of east Australian coastal floodplains. Upon oxidation, these hydromorphic pyritic sediments produce large quantities of sulfuric acid. In addition, due to their geographic location, these soils may also come in contact with high ionic strength estuarine tidal waters. As a result, there is typically a large variation in acidity (pH) and cation concentrations in soil porewaters and adjacent aquatic systems (e.g., agricultural field drains, rivers, estuaries, etc.). Acid sulfate soils, especially from the unoxidized gelatinous deeper layers, contain a relatively high proportion of montmorillonite, which is wellknown for its shrink-swell properties. Variations in cation concentrations, including H 3O +, can influence montmorillonite platelet interactions and may, thus, also significantly affect the hydraulic conductivity of materials containing this clay. In this paper we report on the effect of four common cations, at reasonable environmental concentrations, on the hydraulic properties of potential (unoxidized) acid sulfate soil materials. The natural system was simplified by examining individually the effects of each cation (H +, Ca 2+, Fe 2+ and Na +) on a soil-water suspension in a filtration cell unit. Moisture ratio, hydraulic conductivity and the consolidation coefficient of the deposited filter cakes were calculated using material coordinates theory. The results indicate that the hydraulic conductivity of potential acid sulfate soils increases at low pH and with cation concentration. Although an increase in the charge of amphoteric edge groups on montmorillonite clays may result in some aggregation between individual clay platelets, we conclude that the extent of these changes are unlikely to cause significant increases in the transportation of acidity (and contaminants) through potential acid sulfate soils as the hydraulic conductivity of these materials remain low (<10 -9 m/s) at pH and ionic conditions normally experienced in the field.

Le, T. M. H.; Collins, R. N.; Waite, T. D.

2008-07-01

61

Near-surface soil moisture assimilation for quantifying effective soil hydraulic properties using genetic algorithm: 1. Conceptual modeling  

Microsoft Academic Search

We used a genetic algorithm (GA) to identify soil water retention $\\\\theta$(h) and hydraulic conductivity K(h) functions by inverting a soil-water-atmosphere-plant (SWAP) model using observed near-surface soil moisture (0-5 cm) as search criterion. Uncertainties of parameter estimates were estimated using multipopulations in GA and considering data and modeling errors. Three hydrologic cases were considered: (1) homogenous free-draining soil column, (2)

Amor V. M. Ines; Binayak P. Mohanty

2008-01-01

62

Effects of spatial variability of soil hydraulic properties in water budget modeling  

Microsoft Academic Search

There is appreciable spatial variability of soil properties on the scale of a watershed or a field even in a single soil type. The spatial variation of soil water characteristics in an area was simulated from average properties and the assumption of scale heterogeneity (Philip, 1967). Simulated soil water characteristics and other data representing forest vegetation were used in a

A. J. Peck; R. J. Luxmoore; Janice L. Stolzy

1977-01-01

63

Feasibility of using LANDSAT images of vegetation cover to estimate effective hydraulic properties of soils  

NASA Technical Reports Server (NTRS)

Research activities conducted from February 1, 1985 to July 31, 1985 and preliminary conclusions regarding research objectives are summarized. The objective is to determine the feasibility of using LANDSAT data to estimate effective hydraulic properties of soils. The general approach is to apply the climatic-climax hypothesis (Ealgeson, 1982) to natural water-limited vegetation systems using canopy cover estimated from LANDSAT data. Natural water-limited systems typically consist of inhomogeneous vegetation canopies interspersed with bare soils. The ground resolution associated with one pixel from LANDSAT MSS (or TM) data is generally greater than the scale of the plant canopy or canopy clusters. Thus a method for resolving percent canopy cover at a subpixel level must be established before the Eagleson hypothesis can be tested. Two formulations are proposed which extend existing methods of analyzing mixed pixels to naturally vegetated landscapes. The first method involves use of the normalized vegetation index. The second approach is a physical model based on radiative transfer principles. Both methods are to be analyzed for their feasibility on selected sites.

Eagleson, P. S.

1985-01-01

64

Unsaturated hydraulic conductivity function based on a soil fragmentation process  

E-print Network

Unsaturated hydraulic conductivity function based on a soil fragmentation process Shmuel Assouline-parameter expression for relative hydraulic conductivity (RHC) of partially saturated soils. It is based on the premise. This assumption allows us to derive hydraulic properties of soils (water retention curves and unsaturated

Tartakovsky, Daniel M.

65

Near-surface soil moisture assimilation for quantifying effective soil hydraulic properties using genetic algorithms: 2. Using airborne remote sensing during SGP97 and SMEX02  

NASA Astrophysics Data System (ADS)

Pixel-based effective soil hydraulic parameters are crucial inputs for large-scale hydroclimatic modeling. In this paper, we extend/apply a genetic algorithm (GA) approach for estimating these parameters at the scale of an airborne remote sensing (RS) footprint. To estimate these parameters, we used a time series of near-surface RS soil moisture data to invert a physically based soil-water-atmosphere-plant (SWAP) model with a (multipopulated) modified-microGA. Uncertainties in the solutions were examined in two ways: (1) by solving the inverse problem under various combinations of modeling conditions in a respective way; and (2) the same as the first method but the inverse solutions were determined in a collective way aimed at finding the robust solutions for all the modeling conditions (ensembles). A cross validation of the derived soil hydraulic parameters was done to check their effectiveness for all the modeling conditions used. For our case studies, we considered three electronically scanned thinned array radiometer (ESTAR) footprints in Oklahoma and four polarimetric scanning radiometer (PSR) footprints in Iowa during the Southern Great Plains 1997 (SGP97) Hydrology Experiment and Soil Moisture Experiment 2002 (SMEX02) campaigns, respectively. The results clearly showed the promising potentials of near-surface RS soil moisture data combined with inverse modeling for determining average soil hydrologic properties at the footprint scale. Our cross validation showed that parameters derived by method 1 under water table (bottom boundary) conditions are applicable also for free-draining conditions. However, parameters derived under free-draining conditions generally produced too wet near-surface soil moisture when applied under water table conditions. Method 2, on the other hand, produced robust parameter sets applicable for all modeling conditions used. These results were validated using distributed in situ soil moisture and soil hydraulic properties measurements, and texture-based data from the UNSODA database. In this study, we conclude that inverse modeling of RS soil moisture data is a promising approach for parameter estimation at large measurement support scale. Nevertheless, the derived effective soil hydraulic parameters are subject to the uncertainties of remotely sensed soil moisture data and from the assumptions used in the soil-water-atmosphere-plant modeling. Method 2 provides a flexible framework for accounting these sources of uncertainties in the inverse estimation of large-scale soil hydraulic properties. We have illustrated this flexibility by combining multiple data sources and various modeling conditions in our large-scale inverse modeling.

Ines, Amor V. M.; Mohanty, Binayak P.

2009-01-01

66

Using Remotely-Sensed Estimates of Soil Moisture to Infer Soil Texture and Hydraulic Properties across a Semi-arid Watershed  

NASA Technical Reports Server (NTRS)

Near-surface soil moisture is a critical component of land surface energy and water balance studies encompassing a wide range of disciplines. However, the processes of infiltration, runoff, and evapotranspiration in the vadose zone of the soil are not easy to quantify or predict because of the difficulty in accurately representing soil texture and hydraulic properties in land surface models. This study approaches the problem of parameterizing soils from a unique perspective based on components originally developed for operational estimation of soil moisture for mobility assessments. Estimates of near-surface soil moisture derived from passive (L-band) microwave remote sensing were acquired on six dates during the Monsoon '90 experiment in southeastern Arizona, and used to calibrate hydraulic properties in an offline land surface model and infer information on the soil conditions of the region. Specifically, a robust parameter estimation tool (PEST) was used to calibrate the Noah land surface model and run at very high spatial resolution across the Walnut Gulch Experimental Watershed. Errors in simulated versus observed soil moisture were minimized by adjusting the soil texture, which in turn controls the hydraulic properties through the use of pedotransfer functions. By estimating a continuous range of widely applicable soil properties such as sand, silt, and clay percentages rather than applying rigid soil texture classes, lookup tables, or large parameter sets as in previous studies, the physical accuracy and consistency of the resulting soils could then be assessed. In addition, the sensitivity of this calibration method to the number and timing of microwave retrievals is determined in relation to the temporal patterns in precipitation and soil drying. The resultant soil properties were applied to an extended time period demonstrating the improvement in simulated soil moisture over that using default or county-level soil parameters. The methodology is also applied to an independent case at Walnut Gulch using a new soil moisture product from active (C-band) radar imagery with much lower spatial and temporal resolution. Overall, results demonstrate the potential to gain physically meaningful soils information using simple parameter estimation with few but appropriately timed remote sensing retrievals.

Santanello, Joseph A.; Peters-Lidard, Christa D.; Garcia, Matthew E.; Mocko, David M.; Tischler, Michael A.; Moran, M. Susan; Thoma, D. P.

2007-01-01

67

Changes of soil hydraulic properties from long-term irrigation with desalted brackish groundwater  

NASA Astrophysics Data System (ADS)

Long term effects on soil from desalted water irrigation have been assessed in an experimental plot (9 x 5 m2) under semi-arid climate located in Alicante (SE Spain). Water flux monitoring, from volumetric water content and soil pressure head, was performed from two different monitoring strategies. Also, field scale dispersivity was estimated through a BrLi tracer test and by inverse modelling with HYDRUS. Finally, a reactive and multicomponent transport model was developed using HP1 software, coupling of HYDRUS with PHREEQC. From soil profile characterization, three layers were identified, being calcite the most important mineral of the soil solid phase in all them, followed by quartz and gypsum, the latest in low concentration. Reactive transport modelling of major ions supply by irrigation water was performed with the HP1 code. Temporal and spatial variability of saturated hydraulic conductivity were included in the computational process. Chemical results for each time step (precipitation/dissolution of minerals) were used to compute changes in soil porosity and consequently in the hydraulic conductivity, which is used in the following computational time step. Simulations were performed along a 30 years period. Results from field data show that an increase in porosity and saturated hydraulic conductivity can be expected due to the slow but continuous dissolution of gypsum. Calcite dissolution is expected at the root zone (where partial pressure of CO2 is higher) and precipitation occurs below the root zone, where CO2 partial pressure decreases due to the reduction of biological activity. From the baseline case, three different scenarios were proposed: (i) gypsum free profile, (ii) rain-fed irrigation, and (iii) lower CO2 partial pressure at the root zone. For the gypsum free soil profile scenario, the important precipitation of calcite produced below the root zone is not counteract by the gypsum dissolution, which may lead to significant reduction of hydraulic conductivity under the root zone and also on the recharge rate. Results of rain-red scenario show small changes on hydraulic conductivity, and lower CO2 pressure at the root zone reduces significantly the calcite dissolution and later precipitation.

Valdes-Abellan, Javier; Jiménez-Martínez, Joaquin; Candela, Lucila

2014-05-01

68

Laboratory analysis of soil hydraulic properties of G-5 soil samples  

SciTech Connect

The Hydrologic Testing Laboratory at DBS&A has completed laboratory tests on TA-54 samples from well G5 as specified by Daniel James and summarized in Table 1. Tables 2 through 8 give the results of the specified analyses. Raw laboratory data and graphical plots of data (where appropriate) are contained in Appendices A through G. Appendix H lists the methods used in these analyses. A detailed description of each method is available upon request. Several sample-specific observations are important for data interpretation. Sample G-5 @ 21.5 was a short core and showed indications of preferential flow. Sample G-5 @ 92.5 developed a visually apparent crack during drying which correlates with the higher air permeabilities observed at lower water contents. Several samples yielded negative estimates of extrapolated intrinsic permeability while measured apparent permeabilities were reasonable. For consistency, however, only intrinsic values are presented. While our defined task is to provide data for interpretation, the following comments are offered as a context for some of the common parameter extraction issues. Further details and a more comprehensive summary of TA-54 data can be found in Unsaturated hydraulic characteristics of the Bandelier tuff at TA-54 dated November 17, 1994.

NONE

1995-01-01

69

TRANSLATING AVAILABLE BASIC SOIL DATA INTO MISSING SOIL HYDRAULIC CHARACTERISTICS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Soil hydraulic pedotransfer functions transfer simple-to-measure soil survey information into soil hydraulic characteristics, that are otherwise costly to measure. Examples are presented of different equations describing hydraulic characteristics and of pedotransfer functions used to predict paramet...

70

UNSODA UNSATURATED SOIL HYDRAULIC DATABASE USER'S MANUAL VERSION 1.0  

EPA Science Inventory

This report contains general documentation and serves as a user manual of the UNSODA program. UNSODA is a database of unsaturated soil hydraulic properties (water retention, hydraulic conductivity, and soil water diffusivity), basic soil properties (particle-size distribution, b...

71

RETC CODE FOR QUANTIFYING THE HYDRAULIC FUNCTIONS OF UNSATURATED SOILS  

EPA Science Inventory

This report describes the RETC computer code for analyzing the soil water retention and hydraulic conductivity functions of unsaturated soils. hese hydraulic properties are key parameters in any quantitative description of water flow into and through the unsaturated zone of soils...

72

Coupled water and heat flow in laboratory evaporation experiments and its effects on soil hydraulic properties estimated by the simplified evaporation method  

NASA Astrophysics Data System (ADS)

The prediction of water fluxes in the field requires an accurate determination of soil hydraulic parameters which define the soil water retention and hydraulic conductivity function. The evaporation method has become a standard tool to quickly and reliably determine soil hydraulic properties in the wet to medium pressure head range. Recently, the method has profited from a significant improvement of soil sensors and data evaluation methods. In most cases, the data obtained from a transient evaporation experiment are evaluated using simplifying assumptions, like the ones implicit to Schindler's or Wind's methods. In the past, the effect of these simplifications on the identification of hydraulic properties has been investigated and found to be relatively minor. These studies were based on the evaluation of computer-generated data which were created by numerical modeling of the evaporation process with the Richards equation, i.e. by assuming isothermal liquid flow. Since evaporation from bare soil will always lead to loss of energy, the assumption of constant temperature is questionable. In addition, the effects of thermal and vapor fluxes on simplified evaluation methods have so far hardly been investigated. In this contribution we analyze the effects of (1) coupled heat and water flow and (2) temperature effects on physical parameters. We firstly generated data by a numerical model which solves the coupled heat and water flow problem first derived by Philip and de Vries, and then used these data as source for the estimation of hydraulic properties with the evaluation methods of Schindler and Wind. The virtual realities covered different atmospheric forcings like changing wind speed and varying incoming shortwave radiation. The objective of this study was to identify under which atmospheric conditions, for which soil textures, and in which pressure head range the simplified evaluation methods lead to unbiased estimates of the soil hydraulic properties.

Iden, Sascha C.; Blöcher, Johanna; Diamantopoulos, Efstathios; Durner, Wolfgang

2014-05-01

73

Evaluation of land surface model simulations of evapotranspiration over a 12 year crop succession: impact of the soil hydraulic properties  

NASA Astrophysics Data System (ADS)

Evapotranspiration has been recognized as one of the most uncertain term in the surface water balance simulated by land surface models. In this study, the SURFEX/ISBA-A-gs simulations of evapotranspiration are assessed at local scale over a 12 year Mediterranean crop succession. The model is evaluated in its standard implementation which relies on the use of the ISBA pedotransfer estimates of the soil properties. The originality of this work consists in explicitly representing the succession of crop cycles and inter-crop bare soil periods in the simulations and assessing its impact on the dynamic of simulated and measured evapotranspiration over a long period of time. The analysis focuses on key soil parameters which drive the simulation of evapotranspiration, namely the rooting depth, the soil moisture at saturation, the soil moisture at field capacity and the soil moisture at wilting point. The simulations achieved with the standard values of these parameters are compared to those achieved with the in situ values. The portability of the ISBA pedotransfer functions is evaluated over a typical Mediterranean crop site. Various in situ estimates of the soil parameters are considered and distinct parametrization strategies are tested to represent the evapotranspiration dynamic over the crop succession. This work shows that evapotranspiration mainly results from the soil evaporation when it is continuously simulated over a Mediterranean crop succession. The evapotranspiration simulated with the standard surface and soil parameters of the model is largely underestimated. The deficit in cumulative evapotranspiration amounts to 24% over 12 years. The bias in daily daytime evapotranspiration is -0.24 mm day-1. The ISBA pedotransfer estimates of the soil moisture at saturation and at wilting point are overestimated which explains most of the evapotranspiration underestimation. The overestimation of the soil moisture at wilting point causes the underestimation of transpiration at the end of the crop cycles. The overestimation of the soil moisture at saturation triggers the underestimation of the soil evaporation during the wet soil periods. The use of field capacity values derived from laboratory retention measurements leads to inaccurate simulation of soil evaporation due to the lack of representativeness of the soil structure variability at the field scale. The most accurate simulation is achieved with the values of the soil hydraulic properties derived from field measured soil moisture. Their temporal analysis over each crop cycle provides meaningful estimates of the wilting point, the field capacity and the rooting depth to represent the crop water needs and accurately simulate the evapotranspiration over the crop succession. We showed that the uncertainties in the eddy-covariance measurements are significant and can explain a large part of the unresolved random differences between the simulations and the measurements of evapotranspiration. Other possible model shortcomings include the lack of representation of soil vertical heterogeneity and root profile along with inaccurate energy balance partitioning between the soil and the vegetation at low LAI.

Garrigues, S.; Olioso, A.; Calvet, J.-C.; Martin, E.; Lafont, S.; Moulin, S.; Chanzy, A.; Marloie, O.; Desfonds, V.; Bertrand, N.; Renard, D.

2014-10-01

74

Tillage Effects on Bulk Density and Hydraulic Properties of a Sandy Loam Soil in the Mon-Dak Region, USA  

Technology Transfer Automated Retrieval System (TEKTRAN)

We evaluated the effects of conventional (CT) and strip (ST) tillage practices on bulk density (BD), water content (MC), infiltration rate (Ir) and hydraulic conductivity (Ks) in a Lihen sandy loam soil. Soil cores were collected from each plot at 0 to 10 and 10 to 30 cm depths under each tillage pr...

75

Bulk density, water content and hydraulic properties of a sandy loam soil following conventional or strip tillage  

Technology Transfer Automated Retrieval System (TEKTRAN)

We evaluated the effects of conventional (CT) and strip (ST) tillage practices on bulk density ('b), water content ('w), infiltration rate (Ir) and hydraulic conductivity (Ks) of plots in a Lihen sandy loam soil during the 2007 and 2008 growing seasons. We measured 'b and 'w using soil cores collect...

76

Estimation of Effective Soil Hydraulic Properties Using Data From High Resolution Gamma Densiometry and Tensiometers of Multi-Step-Outflow Experiments  

NASA Astrophysics Data System (ADS)

Dynamic Multi Step Outflow (MSO) experiments serve for the estimation of the parameters from soil hydraulic functions like e.g. the Mualem van Genuchten model. The soil hydraulic parameters are derived from outflow records and corresponding matric potential measurements from commonly a single tensiometer using inverse modeling techniques. We modified the experimental set up allowing for simultaneous measurements of the matric potential with three tensiometers and the water content using a high-resolution gamma-ray densiometry measurement system (Bieberle et al., 2007, Hampel et al., 2007). Different combinations of the measured time series were used for the estimation of effective soil hydraulic properties, representing different degrees of information of the "hydraulic reality" of the sample. The inverse modeling task was solved with the multimethod search algorithm AMALGAM (Vrugt et al., 2007) in combination with the Hydrus1D model (Šimúnek et al., 2008). Subsequently, the resulting effective soil hydraulic parameters allow the simulation of the MSO experiment and the comparison of model results with observations. The results show that the information of a single tensiometer together with the outflow record result in a set of effective soil hydraulic parameters producing an overall good agreement between the simulation and the observation for the location of the tensiometer. Significantly deviating results are obtained for the other tensiometer positions using this parameter set. Inclusion of more information, such as additional matric potential measurements with the according water contents within the optimization procedure lead to different, more representative hydraulic parameters which improved the overall agreement significantly. These findings indicate that more information about the soil hydraulic state variables in space and time are necessary to obtain effective soil hydraulic properties of soil core samples. Bieberle, A., Kronenberg, J., Schleicher, E., Hampel, U., 2007: Design of a high resolution gamma ray detector module for tomography applications, Nuclear Instruments And Methods in Physics Research A, Vol. 572, pp. 668-675. Hampel, U., Bieberle, A., Hoppe, D., Kronenberg, J., Schleicher, E., Sühnel, T., Zimmermann, F., Zippe, C., 2007: High resolution gamma ray tomography scanner for flow measurement and non-destructive testing applications, Review of Scientific Instruments, Vol. 78, 103704. Šimúnek, J., Šejna, M., Saito, H., Sakai, M. & van Genuchten, M. Th., 2008: The Hydrus-1D Software Package for Simulating the Movement of Water, Heat, and Multiple Solutes in Variably Saturated Media, Version 4.0, HYDRUS Software Series 3, Department of Environmental Sciences, University of California Riverside, Riverside, California, USA, pp. 315. Vrugt, J.A. and Robinson, B.A. 2007: Improved evolutionary optimization from genetically adaptive multimethod search, Proc. Nat. Acad. Sci. USA, 104, 708 - 711.

Werisch, Stefan; Lennartz, Franz; Bieberle, Andre

2013-04-01

77

The effect of measured and estimated soil hydraulic properties on simulated water regime in the analysis of grapevine adaptability to future climate  

NASA Astrophysics Data System (ADS)

In the last years many research works have been addressed to evaluate the impact of future climate on crop productivity and plant water use at different spatial scales (global, regional, field) by means of simulation models of agricultural crop systems. Most of these approaches use estimated soil hydraulic properties, through pedotransfer functions (PTF). This choice is related to soil data availability: soil data bases lack measured soil hydraulic properties, but generally they contain information that allow the application of PTF . Although the reliability of the predicted future climate scenarios cannot be immediately validated, we address to evaluate the effects of a simplification of the soil system by using PTF. Thus we compare simulations performed with measured soil hydraulic properties versus simulations carried out with estimated properties. The water regimes resulting from the two procedures are evaluated with respect to crop adaptability to future climate. In particular we will examine if the two procedures bring about different seasonal and spatial variations in the soil water regime patterns, and if these patterns influence adaptation options. The present case study uses the agro-hydrological model SWAP (soil-water-atmosphere and plant) and studies future adaptability of grapevine. The study area is a viticultural area of Southern Italy (Valle Telesina, BN) devoted to the production of high quality wines (DOC and DOCG), and characterized by a complex geomorphology and pedology. The future climate scenario (2021-2050) was constructed applying statistical downscaling techniques to GCMs scenarios. The moisture regime for 25 soils of the selected study area was calculated by means of SWAP model, using both measured and estimated soil hydraulic properties. In the simulation, the upper boundary conditions were derived from the regional climate scenarios. Unit gradient in soil water potential was set as lower boundary condition. Crop-specific input data and model parameters were estimated on the basis of scientific literature and assumed to be generically representative of the species. From the output of the simulation runs, the relative evapotranspiration deficit (or Crop Water Stress Index - CWSI) of the soil units was calculated. Since CWSI is considered an important indicator of the qualitative grapevine responses, its pattern in both simulation procedures has been evaluated. The work was carried out within the Italian national project AGROSCENARI funded by the Ministry for Agricultural, Food and Forest Policies (MIPAAF, D.M. 8608/7303/2008)

Bonfante, Antonello; Alfieri, Silvia Maria; Agrillo, Antonietta; Dragonetti, Giovanna; Mileti, Antonio; Monaco, Eugenia; De Lorenzi, Francesca

2013-04-01

78

Hydraulic Property and Soil Textural Classification Measurements for Rainier Mesa, Nevada Test Site, Nevada  

SciTech Connect

This report presents particle size analysis, field-saturated hydraulic conductivity measurements, and qualitative descriptions of surficial materials at selected locations at Rainier Mesa, Nevada. Measurements and sample collection were conducted in the Rainier Mesa area, including unconsolidated sediments on top of the mesa, an ephemeral wash channel near the mesa edge, and dry U12n tunnel pond sediments below the mesa. Particle size analysis used a combination of sieving and optical diffraction techniques. Field-saturated hydraulic conductivity measurements employed a single-ring infiltrometer with analytical formulas that correct for falling head and spreading outside the ring domain. These measurements may prove useful to current and future efforts at Rainier Mesa aimed at understanding infiltration and its effect on water fluxes and radionuclide transport in the unsaturated zone.

Ebel, Brian A.; Nimmo, John R.

2009-12-29

79

Hydraulic Property and Soil Textural Classification Measurements for Rainier Mesa, Nevada Test Site, Nevada  

USGS Publications Warehouse

This report presents particle size analysis, field-saturated hydraulic conductivity measurements, and qualitative descriptions of surficial materials at selected locations at Rainier Mesa, Nevada. Measurements and sample collection were conducted in the Rainier Mesa area, including unconsolidated sediments on top of the mesa, an ephemeral wash channel near the mesa edge, and dry U12n tunnel pond sediments below the mesa. Particle size analysis used a combination of sieving and optical diffraction techniques. Field-saturated hydraulic conductivity measurements employed a single-ring infiltrometer with analytical formulas that correct for falling head and spreading outside the ring domain. These measurements may prove useful to current and future efforts at Rainier Mesa aimed at understanding infiltration and its effect on water fluxes and radionuclide transport in the unsaturated zone.

Ebel, Brian A.; Nimmo, John R.

2010-01-01

80

Soil Hydraulic Characteristics of a Small Southwest Oregon Watershed Following  

E-print Network

--------------------------------------------- Soil Hydraulic Characteristics of a Small Southwest by a high-intensity burn over areas of steep topography. The areal distribution of soil hydraulic of infiltration capacity, saturated hydraulic conductivity, and soil moisture characteristics. Also, measures

Standiford, Richard B.

81

Numerically predicting seepage gradient forces and erosion sensitivity to soil hydraulic properties  

Technology Transfer Automated Retrieval System (TEKTRAN)

Streambank failures result in loss of land, increased stream sediment loads, and increased nutrient loads if nutrient levels are high. Variably saturated flow models integrated with bank stability models are being used to predict bank failure; however, understanding of the soil characterization nece...

82

UTILITY OF NON-PARAMETRIC 'K-NEAREST NEIGHBOR' ALGORITHMS TO ESTIMATE SOIL HYDRAULIC PROPERTIES  

Technology Transfer Automated Retrieval System (TEKTRAN)

Non-parametric approaches are being used in various fields to address classification type problems, as well as to estimate continuous variables. One type of the non-parametric lazy learning algorithms, a k-Nearest Neighbor (k-NN) algorithm has been developed to estimate soil water retention at –33 a...

83

Monitoring and modeling the soil hydraulic behavior in stony soils  

NASA Astrophysics Data System (ADS)

Describing the soil hydrological behavior at applicative scales remains a complex task, mainly because of the spatial heterogeneity of the vadose zone. Addressing the impact of the unsaturated zone heterogeneity involves measuring and/or modeling water content evolution with fine spatial and temporal resolution. The presence of stones introduces difficulties for both the measurement of the water content and the soil hydraulic properties. In this context, the main objective of this study was to assess the role of stones on TDR-based water content measurements, as well as on the pattern of variability of simulated water contents at field-scale during water infiltration, drainage and evaporation processes. Also, the role of stones was evaluated as one possible explanation of the differences frequently observed between the measured hydraulic behavior and that estimated by using pedotransfer functions.

Dragonetti, Giovanna; Lamaddalena, Nicola; Comegna, Alessandro; Coppola, Antonio

2014-05-01

84

Relationship between Anisotropy in Soil Hydraulic Conductivity and Saturation  

SciTech Connect

Anisotropy in unsaturated hydraulic conductivity is saturation-dependent. Accurate characterization of soil anisotropy is very important in simulating flow and contaminant (e.g., radioactive nuclides in Hanford) transport. A recently developed tensorial connectivity-tortuosity (TCT) concept describes the hydraulic conductivity tensor of the unsaturated anisotropic soils as the product of a scalar variable, the symmetric connectivity tortuosity tensor, and the hydraulic conductivity tensor at saturation. In this study, the TCT model is used to quantify soil anisotropy in unsaturated hydraulic conductivity. The TCT model can describe different types of soil anisotropy; e.g., the anisotropy coefficient, C, can be monotonically increase or decrease with saturation and can vary from greater than unity to less than unity and vice versa. Soil anisotropy is independent of soil water retention properties and can be characterized by the ratio of the saturated hydraulic conductivities and the difference of the tortuosity-connectivity coefficients in two directions. ln(C) is linearly proportional to ln(Se) with Se being the effective saturation. The log-linear relationship between C and Se allows the saturation-dependent anisotropy to be determined using linear regression with the measurements of the directional hydraulic conductivities at a minimum of two water content levels, of which one may be at full saturation. The model was tested using measurements of directional hydraulic conductivities.

Zhang, Z. Fred

2014-06-13

85

Use of LANDSAT images of vegetation cover to estimate effective hydraulic properties of soils  

NASA Technical Reports Server (NTRS)

This work focuses on the characterization of natural, spatially variable, semivegetated landscapes using a linear, stochastic, canopy-soil reflectance model. A first application of the model was the investigation of the effects of subpixel and regional variability of scenes on the shape and structure of red-infrared scattergrams. Additionally, the model was used to investigate the inverse problem, the estimation of subpixel vegetation cover, given only the scattergrams of simulated satellite scale multispectral scenes. The major aspects of that work, including recent field investigations, are summarized.

Eagleson, Peter S.; Jasinski, Michael F.

1988-01-01

86

Effects of Estimating Soil Hydraulic Properties and Root Growth Factor on Soil Water Balance and Crop Production  

Technology Transfer Automated Retrieval System (TEKTRAN)

Increasing water use efficiency (WUE) is one of the oldest goals in agricultural sciences, yet it is still not fully understood and achieved due to the complexity of soil-weather-management interactions. System models that quantify these interactions are increasingly used for optimizing crop WUE, es...

87

Xylem Hydraulics and the SoilPlantAtmosphere Continuum: Opportunities and Unresolved Issues  

E-print Network

Xylem Hydraulics and the Soil­Plant­Atmosphere Continuum: Opportunities and Unresolved Issues John S. Sperry,* Volker Stiller, and Uwe G. Hacke ABSTRACT about the hydraulic properties of the plant vascular sys- tem. The traditional view of plant hydraulics being dom-Soil and xylem are similar

Stiller, Volker

88

Effective hydraulic parameters for steady state vertical flow in heterogeneous soils  

E-print Network

Effective hydraulic parameters for steady state vertical flow in heterogeneous soils Jianting Zhu August 2003. [1] In hydroclimate and land-atmospheric interaction models, effective hydraulic properties are needed at large grid scales. In this study, the effective soil hydraulic parameters of the areally

Mohanty, Binayak P.

89

THE RETC CODE FOR QUANTIFYING THE HYDRAULIC FUNCTIONS OF UNSATURATED SOILS  

EPA Science Inventory

This report describes the RETC computer code for analyzing the soil water retention and hydraulic conductivity functions of unsaturated soils. These hydraulic properties are key parameters in any quantitative description of water flow into and through the unsaturated zone of soil...

90

An evaporation test based on Thermal Infra Red Remote-Sensing to select appropriate soil hydraulic properties  

E-print Network

on the physical link between the soil water diffusion properties and the plant water stress, which has been named properties, pedotransfer functions, infiltration test, evaporation, water stress, TIR remote-sensing, SVAT properties 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 Gilles Boulet1

Paris-Sud XI, Université de

91

The Soil Hydraulic Response to Disturbance and Recovery  

Microsoft Academic Search

While the rate of deforestation in the humid tropics seems to wax and wane with the global demand for certain commodities, the rate of reforestation on degraded lands has been less spectacular. Nonetheless, this process has affected substantial tracts of land in the Amazon basin. We are interested in the rates at which soil hydraulic properties respond to deforestation and

B. Zimmermann; H. Elsenbeer

2006-01-01

92

The effects of vegetation and soil hydraulic properties on passive microwave sensing of soil moisture: Data report for the 1982 fiels experiments  

NASA Technical Reports Server (NTRS)

Field experiments to (1) study the biomass and geometrical structure properties of vegetation canopies to determine their impact on microwave emission data, and (2) to verify whether time series microwave data can be related to soil hydrologic properties for use in soil type classification. Truck mounted radiometers at 1.4 GHz and 5 GHz were used to obtain microwave brightness temperatures of bare vegetated test plots under different conditions of soil wetness, plant water content and canopy structure. Observations of soil moisture, soil temperature, vegetation biomass and other soil and canopy parameters were made concurrently with the microwave measurements. The experimental design and data collection procedures for both experiments are documented and the reduced data are presented in tabular form.

Oneill, P.; Jackson, T.; Blanchard, B. J.; Vandenhoek, R.; Gould, W.; Wang, J.; Glazar, W.; Mcmurtrey, J., III

1983-01-01

93

DEMONSTRATION BULLETIN: HYDRAULIC FRACTURING OF CONTAMINATED SOIL  

EPA Science Inventory

Hydraulic fracturing is a physical process that creates fractures in silty clay soil to enhance its permeability. The technology, developed by the Risk Reduction Engineering Laboratory (RREL) and the University of Cincinnati, creates sand-filled horizontal fractures up to 1 in. i...

94

Cautionary notes on the use of the Rawls et al. (1982) soil hydraulic pedotransfer functions  

Technology Transfer Automated Retrieval System (TEKTRAN)

Environmental and crop simulation models use a wide range of inputs that include soil hydraulic properties. For many applications, use of laboratory determined soil water retention and hydraulic conductivity data is not feasible; therefore those need to be estimated. The current version of the Agric...

95

Onset of water stress, hysteresis in plant conductance, and hydraulic lift: Scaling soil water dynamics  

E-print Network

effective is dictated by soil hydraulic properties and surrogates for atmospheric water vapor demandOnset of water stress, hysteresis in plant conductance, and hydraulic lift: Scaling soil water] Estimation of water uptake by plants and subsequent water stress are complicated by the need to resolve

Katul, Gabriel

96

Project Summary. THE RETC CODE FOR QUANTIFYING THE HYDRAULIC FUNCTIONS OF UNSATURATED SOILS  

EPA Science Inventory

This summary describes the RETC computer code for analyzing the soil water retention and hydraulic conductivity functions of unsaturated soils. These hydraulic properties are key parameters in any quantitative description of water flow into and through the unsaturated zone of soi...

97

The Soil Hydraulic Response to Disturbance and Recovery  

NASA Astrophysics Data System (ADS)

While the rate of deforestation in the humid tropics seems to wax and wane with the global demand for certain commodities, the rate of reforestation on degraded lands has been less spectacular. Nonetheless, this process has affected substantial tracts of land in the Amazon basin. We are interested in the rates at which soil hydraulic properties respond to deforestation and reforestation, and in the effect of land-use history before reforestation on these rates. The preliminary results from ongoing true and false time series experiments in the south-western Amazon basin of Brazil and the montane rainforest of eastern Ecuador emphasize a pronounced asymmetry of the soil hydraulic response to disturbance and recovery: whereas just one year of extensive grazing upon pasture establishment reduces infiltrability and topsoil permeability by more than half, more than ten years of secondary succession or afforestation with commercial tree species are required to elicit an increase in these soil properties. The rate of recovery depends on the kind and duration of land-use before abandonment and reforestation: it is slow after prolonged grazing and rapid after short agricultural use. We conclude that a soil hydraulic pasture imprint may be preserved for many years during secondary succession, and hence that secondary forests and plantations continue to behave hydrologically like pastures for many years.

Zimmermann, B.; Elsenbeer, H.

2006-12-01

98

Incorporating Soil Hydraulic Parameter Statistics in Developing Pedo-transfer Functions  

NASA Astrophysics Data System (ADS)

In this study, we develop artificial neural network (ANN) based pedotransfer functions (PTFs) to predict soil hydraulic properties. The PTF approach is an efficient way of translating less costly available data, such as particle-size distributions, soil textures and other geophysical measurements, to soil hydraulic parameters required for numerical simulations and other applications. The ANN PTFs need to be trained before being used to transfer indirect measurements to soil hydraulic parameters. The traditional training process, in general, is to adjust ANN's coefficients to solely minimize the difference between the estimated and measured soil hydraulic parameters. The training process, however, did not consider the distributions of soil hydraulic parameters and the trained neural networks may yield improper distributions, which may severely affect probabilistic predictions. We incorporate the distributions of the soil hydraulic parameters into the ANN PTF development. In addition, it has been observed that PTFs can introduce unrealistic correlations between the output parameters. The unwanted artificial correlations need to be penalized during the training process, since it is well known that parameter correlations have significant effect on predictions. We achieve these two goals by adding two regularization terms to the ANN objective functions. A suite of new neural network models are developed to estimate soil hydraulic parameters. These neural network models have the same input and output variables, but different objective functions, which incorporate sequentially the site soil hydraulic parameter measurements, parameter probability distributions, and parameter correlations.

Zhao, Y.; Zhu, J.; Ye, M.; Meyer, P. D.; Pan, F.; Hassan, A. E.

2007-12-01

99

Interaction between soil mineralogy and the application of crop residues on aggregate stability and hydraulic conductivity of the soil  

NASA Astrophysics Data System (ADS)

One of the main goals of modern agriculture is to achieve sustainability by maintaining crop productivity while avoiding soil degradation. Intensive cultivation could lead to a reduction in soil organic matter that could affect the structure stability and hydraulic conductivity of the soil. Moreover, crops extract nutrients from the soil that are taken away from the field when harvested, and as a consequence, the addition of fertilizers to the soil is necessary to maintain crop productivity. One way to deal with these problems is to incorporate crop residues into the soil after harvest. Crop residues are a source of organic matter that could improve soil physical properties, such as aggregate stability and soil hydraulic conductivity. However, this effect could vary according to other soil properties, such as clay content, clay mineralogy, and the presence of other cementing materials in the soil (mainly carbonates and aluminum and iron oxides). In the present work, the interaction between the addition of chickpea crop residues to the soil and clay mineralogy on aggregate stability and saturated hydraulic conductivity were studied. Chickpea plant residues were added at a rate of 0.5% (w/w) to smectitic, kaolinitic, illitic and non-phyllosilicate soils from different regions. The soils without (control) and with chickpea residues were incubated for 0, 3, 7 and 30 days, and the saturated hydraulic conductivity of the soils was measured in columns after each incubation time. The response of hydraulic conductivity to the addition of residues and incubation time was different in the soils with various mineralogies, although in general, the addition of chickpea residues increased the saturated hydraulic conductivity as compared with the control soils. This positive effect of crop residues on hydraulic conductivity was mainly a result of improved aggregate stability and resistance to slaking during wetting.

Lado, M.; Kiptoon, R.; Bar-Tal, A.; Wakindiki, I. I. C.; Ben-Hur, M.

2012-04-01

100

Using random forests to explore the effects of site attributes and soil properties on near-saturated and saturated hydraulic conductivity  

NASA Astrophysics Data System (ADS)

Knowledge of the near-saturated and saturated hydraulic conductivity of soil is fundamental for understanding important processes like groundwater contamination risks or runoff and soil erosion. Hydraulic conductivities are however difficult and time-consuming to determine by direct measurements, especially at the field scale or larger. So far, pedotransfer functions do not offer an especially reliable alternative since published approaches exhibit poor prediction performances. In our study we aimed at building pedotransfer functions by growing random forests (a statistical learning approach) on 486 datasets from the meta-database on tension-disk infiltrometer measurements collected from peer-reviewed literature and recently presented by Jarvis et al. (2013, Influence of soil, land use and climatic factors on the hydraulic conductivity of soil. Hydrol. Earth Syst. Sci. 17(12), 5185-5195). When some data from a specific source publication were allowed to enter the training set whereas others were used for validation, the results of a 10-fold cross-validation showed reasonable coefficients of determination of 0.53 for hydraulic conductivity at 10 cm tension, K10, and 0.41 for saturated conductivity, Ks. The estimated average annual temperature and precipitation at the site were the most important predictors for K10, while bulk density and estimated average annual temperature were most important for Ks prediction. The soil organic carbon content and the diameter of the disk infiltrometer were also important for the prediction of both K10 and Ks. However, coefficients of determination were around zero when all datasets of a specific source publication were excluded from the training set and exclusively used for validation. This may indicate experimenter bias, or that better predictors have to be found or that a larger dataset has to be used to infer meaningful pedotransfer functions for saturated and near-saturated hydraulic conductivities. More research is in progress to further elucidate this question.

Jorda, Helena; Koestel, John; Jarvis, Nicholas

2014-05-01

101

Estimating soil hydraulic parameters from transient flow experiments in a centrifuge using parameter optimization technique  

USGS Publications Warehouse

A modified version of the Hydrus software package that can directly or inversely simulate water flow in a transient centrifugal field is presented. The inverse solver for parameter estimation of the soil hydraulic parameters is then applied to multirotation transient flow experiments in a centrifuge. Using time-variable water contents measured at a sequence of several rotation speeds, soil hydraulic properties were successfully estimated by numerical inversion of transient experiments. The inverse method was then evaluated by comparing estimated soil hydraulic properties with those determined independently using an equilibrium analysis. The optimized soil hydraulic properties compared well with those determined using equilibrium analysis and steady state experiment. Multirotation experiments in a centrifuge not only offer significant time savings by accelerating time but also provide significantly more information for the parameter estimation procedure compared to multistep outflow experiments in a gravitational field. Copyright 2005 by the American Geophysical Union.

Simunek, J.; Nimmo, J.R.

2005-01-01

102

Hydraulic Properties of Rice and the Response of Gas Exchange to Water Stress1  

E-print Network

Hydraulic Properties of Rice and the Response of Gas Exchange to Water Stress1 Volker Stiller*, H.R.L.) We investigated the role of xylem cavitation, plant hydraulic conductance, and root pressure-specific photosynthetic rate, leaf diffusive conductance, and soil-leaf hydraulic conductance that were associated

Stiller, Volker

103

rosetta: a computer program for estimating soil hydraulic parameters with hierarchical pedotransfer functions  

Microsoft Academic Search

Soil hydraulic properties are necessary for many studies of water and solute transport but often cannot be measured because of practical and\\/or financial constraints. We describe a computer program, rosetta, which implements five hierarchical pedotransfer functions (PTFs) for the estimation of water retention, and the saturated and unsaturated hydraulic conductivity. The hierarchy in PTFs allows the estimation of van Genuchten

Marcel G. Schaap; Feike J. Leij; Martinus Th. van Genuchten

2001-01-01

104

Inverse modelling in estimating soil hydraulic functions: a Genetic Algorithm approach Hydrology and Earth System Sciences, 6(1), 4965 (2002) EGS  

E-print Network

and Earth System Sciences, 6(1), 49­65 (2002) © EGS Inverse modelling in estimating soil hydraulic functionsInverse modelling in estimating soil hydraulic functions: a Genetic Algorithm approach 49 Hydrology is sometimes hindered by the difficulty of deriving the soil hydraulic properties of the study area

Paris-Sud XI, Université de

105

Dynamic aspects of soil water availability for isohydric plants: Focus on root hydraulic resistances  

NASA Astrophysics Data System (ADS)

water availability for plant transpiration is a key concept in agronomy. The objective of this study is to revisit this concept and discuss how it may be affected by processes locally influencing root hydraulic properties. A physical limitation to soil water availability in terms of maximal flow rate available to plant leaves (Qavail) is defined. It is expressed for isohydric plants, in terms of plant-centered variables and properties (the equivalent soil water potential sensed by the plant, ?s eq; the root system equivalent conductance, Krs; and a threshold leaf water potential, ?leaf lim). The resulting limitation to plant transpiration is compared to commonly used empirical stress functions. Similarities suggest that the slope of empirical functions might correspond to the ratio of Krs to the plant potential transpiration rate. The sensitivity of Qavail to local changes of root hydraulic conductances in response to soil matric potential is investigated using model simulations. A decrease of radial conductances when the soil dries induces earlier water stress, but allows maintaining higher night plant water potentials and higher Qavail during the last week of a simulated 1 month drought. In opposition, an increase of radial conductances during soil drying provokes an increase of hydraulic redistribution and Qavail at short term. This study offers a first insight on the effect of dynamic local root hydraulic properties on soil water availability. By better understanding complex interactions between hydraulic processes involved in soil-plant hydrodynamics, better prospects on how root hydraulic traits mitigate plant water stress might be achieved.

Couvreur, V.; Vanderborght, J.; Draye, X.; Javaux, M.

2014-11-01

106

Influence of long-term tillage and crop rotations on soil hydraulic properties in the U.S. Pacific Northwest  

Technology Transfer Automated Retrieval System (TEKTRAN)

In the semi-arid region of the Pacific Northwest, USA, no-tillage continuous spring cereal and spring cereal/chemical fallow rotations are being examined as alternatives to the traditional winter wheat/summer fallow rotation for improving soil and water conservation. There is limited information, ho...

107

Climate, vegetation, and soil controls on hydraulic redistribution in shallow tree roots  

NASA Astrophysics Data System (ADS)

Hydraulic redistribution defined as the translocation of soil moisture by plant root systems in response to water potential gradients is a phenomenon widely documented in different climate, vegetation, and soil conditions. Past research has largely focused on hydraulic redistribution in deep tree roots with access to groundwater and/or winter rainfall, while the case of relatively shallow (i.e., ?1-2 m deep) tree roots has remained poorly investigated. In fact, it is not clear how hydraulic redistribution in shallow root zones is affected by climate, vegetation, and soil properties. In this study, we developed a model to investigate the climate, vegetation, and soil controls on the net direction and magnitude of hydraulic redistribution in shallow tree root systems at the growing season to yearly timescale. We used the model to evaluate the effect of hydraulic redistribution on the water stress of trees and grasses. We found that hydraulic lift increases with decreasing rainfall frequency, depth of the rooting zone, root density in the deep soil and tree leaf area index; at the same time for a given rainfall frequency, hydraulic lift increases with increasing average rainstorm depth and soil hydraulic conductivity. We propose that water drainage into deeper soil layers can lead to the emergence of vertical water potential gradients sufficient to explain the occurrence of hydraulic lift in shallow tree roots without invoking the presence of a shallow water table or winter precipitation. We also found that hydraulic descent reduces the water stress of trees and hydraulic lift reduces the water stress of grass with important implications on tree-grass interactions.

Yu, Kailiang; D'Odorico, Paolo

2014-04-01

108

Unsaturated soil hydraulic conductivity: The field infiltrometer method  

Technology Transfer Automated Retrieval System (TEKTRAN)

Theory: Field methods to measure the unsaturated soil hydraulic conductivity assume presence of steady-state water flow. Soil infiltrometers are desired to apply water onto the soil surface at constant negative pressure. Water is applied to the soil from the Marriott device through a porous membrane...

109

Sensitivity and uncertainty analysis of estimated soil hydraulic parameters for simulating soil water content  

NASA Astrophysics Data System (ADS)

The sensitivity and uncertainty analysis has been carried out for the scalar parameters (soil hydraulic parameters (SHPs)), which govern the simulation of soil water content in the unsaturated soil zone. The study involves field experiments, which were conducted in real field conditions for wheat crop in Roorkee, India under irrigated conditions. Soil samples were taken for the soil profile of 60 cm depth at an interval of 15 cm in the experimental field to determine soil water retention curves (SWRCs). These experimentally determined SWRCs were used to estimate the SHPs by least square optimization under constrained conditions. Sensitivity of the SHPs estimated by various pedotransfer functions (PTFs), that relate various easily measurable soil properties like soil texture, bulk density and organic carbon content, is compared with lab derived parameters to simulate respective soil water retention curves. Sensitivity analysis was carried out using the monte carlo simulations and the one factor at a time approach. The different sets of SHPs, along with experimentally determined saturated permeability, are then used as input parameters in physically based, root water uptake model to ascertain the uncertainties in simulating soil water content. The generalised likelihood uncertainty estimation procedure (GLUE) was subsequently used to estimate the uncertainty bounds (UB) on the model predictions. It was found that the experimentally obtained SHPs were able to simulate the soil water contents with efficiencies of 70-80% at all the depths for the three irrigation treatments. The SHPs obtained from the PTFs, performed with varying uncertainties in simulating the soil water contents. Keywords: Sensitivity analysis, Uncertainty estimation, Pedotransfer functions, Soil hydraulic parameters, Hydrological modelling

Gupta, Manika; Garg, Naveen Kumar; Srivastava, Prashant K.

2014-05-01

110

SOIL MOISTURE RETENTION CHARACTERISTICS AND HYDRAULIC CONDUCTIVITY FOR DIFFERENT AREAS IN INDIA IN SELECTED STATES  

E-print Network

SOIL MOISTURE RETENTION CHARACTERISTICS AND HYDRAULIC CONDUCTIVITY FOR DIFFERENT AREAS IN INDIA systems require knowledge of the relationships between soil moisture content (), soil water pressure (h) and unsaturated hydraulic conductivity (K). This study involved field and laboratory determination of soil

Kumar, C.P.

111

Using Remotely-Sensed Estimates of Soil Moisture to Infer Soil Texture and Hydraulic Properties across a Semi-arid Watershed 1856  

Technology Transfer Automated Retrieval System (TEKTRAN)

Near-surface soil moisture is a critical component of land surface energy and water balance studies encompassing a wide range of disciplines. However, the processes of infiltration, runoff, and evapotranspiration in the vadose zone of the soil are not easy to quantify or predict because of the diff...

112

Study on The Spatial Variability of Soil Hydraulic Conductivities in Heterogenic Karst Slopes  

NASA Astrophysics Data System (ADS)

The understanding of the spatial variability of soil hydraulic property is crucial to the study of several hydrological and ecological processes in karst environments. Karst environments are extremely fragile because of thin soil, small soil water holding capacity and quite high soil distribution heterogeneity. A marked intensification of agricultural land use and deforestation due to increase of population and thus expansion of agricultural areas has made the karst environment even more delicate. In this study, soil properties and soil hydraulic conductivities (K) along six land use types karst slopes were measured, each of which has a different karst microhabitats including the Soil Surface (thick soil layer), Rock-Soil (thin soil layer contacting rock surface) and Karren Soil (soil filled in rock crevices or fractures). The statistical results from the measurements show that: 1. The soil hydraulic conductivities in forest area were quite high compared to non-karst areas because of the thin soil and cracks and fractures well development in carbonate rocks. 2. Land use changes strongly affect the soil properties and soil hydraulic conductivities (K) in these karst microhabitats. Compared with undisturbed forest karst slopes, the K values are 54.5% and 61.8% smaller in the fire or cut and the pasture human disturbed areas, respectively. Human activities significantly change soil properties and decrease permeability of soils when the forest was destroyed. Measured K values were 0.3~1cm/min and 0.2~0.3 cm/min for the forest soils and the human disturbed areas, respectively. However, these decreasing trends of the K values in the three types of karst microhabitats were different. The K values were decreased significantly in the Soil Surface and Rock-Soil microhabitats, compared to that of Karren Soil microhabitats when the land use change from forest to cutting or pasture area. The K values decreased 71.9% and 79.6% in Soil Surface and Rock-Soil microhabitats, and it were reduced by 36.5% in Karren Soil. It means that soil in rock crevices or fractures microhabitats in karst slopes were less influenced by the land use changes. These results offer useful information to further investigate the response of ecosystem evolution to hydrodynamic processes in highly heterogeneity karst slopes.

Peng, Tao; Fang, Sheng; Meng, Fan-De; Wang, Shi-Jie

2013-04-01

113

Identification of optimal soil hydraulic functions and parameters for predicting soil moisture  

EPA Science Inventory

We examined the accuracy of several commonly used soil hydraulic functions and associated parameters for predicting observed soil moisture data. We used six combined methods formed by three commonly used soil hydraulic functions ? i.e., Brooks and Corey (1964) (BC), Campbell (19...

114

Appendix A. Hydraulic Properties Statistics Tables Table A1. Hydraulic properties statistics for the alluvium (Stephens et al.).  

E-print Network

A-1 Appendix A. Hydraulic Properties Statistics Tables Table A1. Hydraulic properties statistics Deviation .1708 4.274 28.95 Harmonic Mean Number of Observations 9 8 8 2 2 2 2 2 Table A2. Hydraulic.3Ã?10-5 Number of Observations 10 10 10 34 34 4 4 4 #12;A-2 Table A3. Hydraulic properties statistics

115

Ecological Modelling 154 (2002) 263288 Forest canopy hydraulic properties and catchment water  

E-print Network

Ecological Modelling 154 (2002) 263­288 Forest canopy hydraulic properties and catchment water observed. However, mid-day leaf water potentials and the leaf area-specific canopy hydraulic conductance canopy model with a 1-D soil column model and TOPMODEL hydrologic formulations. The SPA model was used

116

Pedotransfer functions: bridging the gap between available basic soil data and missing soil hydraulic characteristics  

Microsoft Academic Search

Water retention and hydraulic conductivity are crucial input parameters in any modelling study on water flow and solute transport in soils. Due to inherent temporal and spatial variability in these hydraulic characteristics, large numbers of samples are required to properly characterise areas of land. Hydraulic characteristics can be obtained from direct laboratory and field measurements. However, these measurements are time

J. H. M. Wösten; Ya. A. Pachepsky; W. J. Rawls

2001-01-01

117

Measurement of soil hydraulic conductivity in relation with vegetation  

NASA Astrophysics Data System (ADS)

Hydraulic conductivity is a key parameter which influences hydrological processes of infiltration, surface and subsurface runoff. Vegetation alters surface characteristics (e.g., surface roughness, litter absorption) or subsurface characteristics (e.g. hydraulic conductivity). Field infiltration experiment of a single ring permeameter is widely used for measuring soil hydraulic conductivity. Measurement equipment is a simple single-ring falling head permeameter which consists of a hollow cylinder that is simply inserted into the top soil. An optimization method on the basis of objective of minimum error between the measured and simulated water depths in the single-ring is developed for determination of the soil hydraulic parameters. Using the single ring permeameter, we measured saturated hydraulic conductivities (Ks) of the red loam soil with and without vegetation covers on five hillslopes at Taoyuan Agro-Ecology Experimental Station, Hunan Province of China. For the measurement plots without vegetation roots, Ks value of the soil at 25cm depth is much smaller than that of surface soil (1.52×10-4 vs. 1.10×10-5 m/s). For the measurement plots with vegetation cover, plant roots significantly increase Ks of the lower layer soil but this increase is not significant for the shallow soil. Moreover, influences of vegetation root on Ks depend on vegetation species and ages. Ks value of the Camellia is about three times larger than that of seeding of Camphor (2.62×10-4 vs. 9.82×10-5 m/s). Ks value of the matured Camellia is 2.72×10-4 m/s while Ks value of the young Camellia is only 2.17×10-4 m/s. Key words: single ring permeameter; soil hydraulic conductivity; vegetation

Chen, Xi; Cheng, Qinbo

2010-05-01

118

Estimating sphagnum peat hydraulic properties from laboratory evaporation experiments  

NASA Astrophysics Data System (ADS)

In ombrotrophic peatlands, the equilibrium between the production and decay of organic matter is principally controlled by the moisture state and its oxic/anoxic conditions in the vadose zone. In order to predict a peatland's fate, it is necessary to describe the hydraulic processes with models correctly. However, no suitable systematic and mechanistic model exists to date. This knowledge gap is attributed to the complexity of peatland ecosystem processes. The reasons for this probably include spatial and temporal heterogeneities, swelling and shrinkage phenomena, hydrophobicity and difficulties in representative sampling. For a valid description of the non-linear processes involved, peat soil hydraulic properties play an intricate part. Their determination requires taking the characteristics mentioned into considered. Our research aims to quantify these characteristics and, eventually, to establish a model in order to numerically simulate the water fluxes in the unsaturated zone. We started with laboratory measurements with which we determined peat soil hydraulic properties. Our study is based on an ombrotrophic peatland site in the Harz Mountains (Germany). Samples were taken over the entire unsaturated part of a Histosol profile. Before the laboratory experiments, samples were frozen, cut to shape and subsequently fully saturated in a vacuum. We used the same sample specimen for the saturated hydraulic conductivity and the simplified evaporation method. Results show that the hydraulic properties rapidly change in the upper-most layers with a step-like change over a small distance, close to the permanently saturated zone. We also show that the swelling and shrinkage is considerable, which means that traditional concepts based on the rigidity of the porous media are not applicable. Furthermore, the results indicate that the frequently used van Genuchten model cannot describe our data very well.

Weber, Tobias K. D.; Durner, Wolfgang

2013-04-01

119

Topographic and soil hydraulic control of flow paths and soil contact time: Effects on surface-water acidification  

SciTech Connect

Topography and soil hydraulic properties are catchment attributes thought to influence the contact time of water in the soils and rocks of a catchment and the flow path followed by water as it traverses the catchment. Soil contact time and flow path, in turn, may affect the chemical composition of surface waters. The main objective of this dissertation is to determine to what extent variability in the topographic and soil hydraulic characteristics of catchments explains differences in the surface water acidification of those catchments. The theoretical framework of the hydrological model TOPMODEL was analyzed to determine how topographic and soil hydraulic catchment characteristics can be used to derive theoretical indices of flow path and soil contact time. These hydrological induces were derived from observed topography and soil hydraulic attributes and compared to observations of base flow alkalinity for 145 catchments in the Northeast US and to observations of storm flow acidity for 8 catchments in Wales. A significant proportion of the variability in base flow alkalinity for the catchments in the Northeast US was attributable to differences in the soil contact time index derived from catchment topography, soil depth and saturated hydraulic conductivity data. Generally, catchments with long soil contact time indices had higher base flow alkalinities. In addition, a large component of the variability in storm flow acidity for the catchments in Wales was explained by catchment differences in a flow path index based on topography. Storm flow acidity was higher in the catchments that were theoretically most likely to produce surface and near-surface runoff.

Wolock, D.M.

1988-01-01

120

Polyacrylamide effect on hydraulic conductivity of hardsetting soils in Northeast of Brazil  

NASA Astrophysics Data System (ADS)

Among soil hydro-physical properties, hydraulic conductivity is more sensitive to changes in soil structure. Hydraulic conductivity describes the ease with which a fluid (usually water) can move through pore spaces or fractures. It depends on the intrinsic permeability of the material and on the degree of saturation, and on the density and viscosity of the fluid. Hardsetting soils present very low hydraulic conductivity values. When dry, these soils show high penetration resistance and consistency extremely hard, but change to friable when moist. In this condition are poorly structured, slaking when moist, limit agricultural machinery use and it may reduce the growth of the root system. In Brazil, these soils occur throughout of coastal zone in flat areas called "coastal tableland". Chemical ameliorant, such as polymers based on anionic polyacrylamide (PAM), improve hydraulic conductivity of soil in hardsetting soils. The primary functions of polyacrylamide soil conditioners are to increase soil tilth, aeration, and porosity and reduce compaction and water run-off. PAM effect is attributed to its ability to expand when placed in water, storing it in soil pore space, releasing it gradually to the plants. This process occurs by reducing the water flow through the pores of the soil, due to water molecules can be absorbed by PAM, providing water gradually. Thus, this study tested the hypothesis that PAM reduces the soil hardsetting character. The area is located in coastal zone in Goiana city, Pernambuco, northeastern of Brazil. This soil is typical hardsetting soil. Intact soil cores were collected from four horizons until 70cm depth. In the laboratory, the soil cores were saturated with different PAM concentrations (0.01, 0.005, 0.00125%) and H2O (control). Saturated hydraulic conductivity (Ksat) was determined using a constant head method, according to Klute and Dirksen (1986). Four replicates were used for each horizon and Tukey test at 5% probability was used by Assistat 7.6 beta. The sandy horizon had higher hydraulic conductivity in natural conditions, and the PAM, especially the concentration of 0.010%, reduced Ksat. This result confirms the action agglutinant of PAM organizing sand particles on aggregates, providing higher water retention, reducing water drainage and also Ksat values. In the other, especially in hardsetting horizon, when the lowest concentration (0.00125%) was applied reduced the effect of cohesion realized by increasing Ksat value. In conclude, PAM in hardsetting soils improve its physico-water proprieties when low concentrations.

Silva, Laércio; Almeida, Brivaldo; Melo, Diego; Marques, Karina; Almeida, Ceres

2013-04-01

121

Centrifuge Permeameter for Unsaturated Soils. II: Measurement of the Hydraulic Characteristics  

E-print Network

Centrifuge Permeameter for Unsaturated Soils. II: Measurement of the Hydraulic Characteristics and hydraulic conductivity function K function , determined using a new centrifuge permeameter developed hydraulic characteristics of the compacted clay. The SWRCs and K functions defined using the centrifuge

Zornberg, Jorge G.

122

Data Acquisition System for Steady-State Hydraulic Soil Conductivity Measurements  

Microsoft Academic Search

This paper presents the design and construction of an automated single-ring infiltrometer for investigating soil hydraulic conductivity properties. The design is intended for increasing the quality and quantity of data, compared to manually recorded measurements, while reducing direct measurement time investment. The device consists of perspex pipe (Mariotte bottle with openings), a metallic ring, a differential pressure sensor and a

J. A. G. Gnecchi; G. M. C. Campos; A. G. T. Chavez

2009-01-01

123

Now Ain't that Swell? A New Method for Measuring Hydraulic Conductivity in Expansive Soils  

NASA Astrophysics Data System (ADS)

In many clay soils, properties such as specific volume, void ratio and hydraulic conductivity vary as the soil shrinks and swells with changing water content. While much research has been devoted to understanding and predicting changes in specific volume and void ratio in these soils, changes in hydraulic conductivity have received relatively little attention. We present a new laboratory method for concurrently measuring the evolution of saturated hydraulic conductivity and the specific volume of soil cores as they are exposed to water flow. The differential in potential to drive flow is imposed by applying negative pressures at the outlet, which may be varied to measure the role of confining pressure. Under small negative pressures (less than -0.2 bar), the soil cores are able to swell as they hydrate. This is in contrast to traditional rigid-wall permeameters, which unnaturally restrain the swelling, or to flexible-wall permeameters, which are generally operated with the sample placed under a constant constraining pressure. As a result, we are able to assess the interdependence of hydraulic conductivity, confining pressure, and degree of swelling in soil cores.

Stewart, R. D.; Abou Najm, M. R.; Rupp, D. E.; Selker, J. S.

2012-12-01

124

In situ separation of root hydraulic redistribution of soil water from liquid and vapor transport  

SciTech Connect

Nocturnal increases in water potential ( ) and water content (WC) in the upper soil profile are often attributed to root water efflux into the soil, a process termed hydraulic lift or hydraulic redistribution (HR). We have previously reported HR values up to ~0.29 mm day-1 in the upper soil for a seasonally dry old-growth ponderosa pine site. However, unsaturated liquid or vapor flux of water between soil layers independent of roots also contributes to the diurnal patterns in WC, confounding efforts to determine the actual magnitude of HR. In this study, we estimated liquid (Jl) and vapor (Jv) soil water fluxes and their impacts on quantifying HR in situ by applying existing data sets of , WC, temperature (T) and soil physical properties to soil water transport equations. Under moist conditions, Jl between layers was estimated to be larger than necessary to account for measured nocturnal increases in WC of upper soil layers. However, as soil drying progressed unsaturated hydraulic conductivity declined rapidly such that Jl was irrelevant (< 2E-06 cm hr-1 at 0-60 cm depths) to total water flux by early August. In surface soil at depths above 15 cm, large T fluctuations can impact Jv leading to uncertainty concerning the role, if any, of HR in nocturnal WC dynamics. Vapor flux was estimated to be the highest at the shallowest depths measured (20 - 30 cm) where it could contribute up to 40% of hourly increases in nocturnal soil moisture depending on thermal conditions. While both HR and net soil water flux between adjacent layers contribute to WC in the 15-65 cm soil layer, HR was the dominant process and accounted for at least 80% of the diurnal increases in WC. While the absolute magnitude of HR is not easily quantified, total diurnal fluctuations in upper soil water content can be quantified and modeled, and remain highly applicable for establishing the magnitude and temporal dynamics of total ecosystem water flux.

Warren, Jeffrey [ORNL; Brooks, J Renee [U.S. Environmental Protection Agency, Corvallis, OR; Dragila, Maria [Oregon State University, Corvallis; Meinzer, Rick [USDA Forest Service

2011-01-01

125

Experimental Determination of Hydraulic Properties of Unsaturated Calcarenites  

NASA Astrophysics Data System (ADS)

Understanding hydraulic properties is essential in the modeling of flow and solute transport through the vadose zone, to which problems of soil and groundwater pollution are related. The vadose zone, in fact, is of great importance in controlling groundwater recharge and transport of contaminants into and through the subsoil. The aim of this work is to determine experimentally in laboratory the hydraulic properties of unsaturated calcarenites using an approach including petrophysical determinations and methods for measuring water retention. For this purpose, samples of calcarenites belonging to the Calcarenite di Gravina Fm.(Pliocene-early Pleistocene), came from two different quarry districts located in Southern Italy (Canosa di Puglia and Massafra), were utilized. The water retention function, ?(h), which binds the water content, ?, to water potential, h, was determined in the laboratory by means two different experimental methods: the WP4-T psychrometer and the suction table. At last, a simple mathematical equation represented by van Genuchten's model is fitted to the experimental data and the unknown empirical parameters of this model are determined. Textural analysis on thin sections using optical petrographic microscopy and evaluation of total and effective porosity by means of standard geotechnical laboratory tests, mercury intrusion porosimetry and image analysis were also performed. In particular, a comparison between mercury porosimetry data and results of photomicrograph computer analysis through the methods of quantitative stereology was employed for providing pore size distributions. The results of this study identify the relationship between the hydraulic behavior, described by the water retention function, and pore size distribution for the calcarenites that are not easy to hydraulically characterize. This relationship could represent a useful tool to infer the unsaturated hydraulic properties of calcarenites and in general this approach could be applied to be used for different kinds of rocks.

Turturro, Antonietta Celeste; Andriani, Gioacchino Francesco; Clementina Caputo, Maria; Maggi, Sabino

2013-04-01

126

ORIGINAL PAPER Hydraulic properties and embolism in small-diameter  

E-print Network

ORIGINAL PAPER Hydraulic properties and embolism in small-diameter roots of five temperate broad & Context It has been estimated that about half of a plant's total hydraulic resistance is located belowground, but it is not well known how temperate tree species differ in root hydraulic properties and how

Paris-Sud XI, Université de

127

Hydraulic conductivity estimation for soils with heterogeneous pore structure  

Microsoft Academic Search

The hydraulic conductivity function, which is required to solve the Richards equation, is difficult to measure. Therefore prediction methods are frequently used where the shape of the conductivity function is estimated from the more easily measured water retention characteristic. Errors in conductivity estimations can arise either from an invalidity of the prediction model for a given soil, or from an

Wolfgang Durner

1994-01-01

128

Seasonal variability of near-saturated hydraulic conductivity on cultivated soil  

NASA Astrophysics Data System (ADS)

The soil structure and hydraulic properties of arable soils considerably vary during the year due to the periodical tillage and fertilization activities, soil compaction, plant and root grow, climate impact etc. The knowledge of the effect of temporal soil variability is essential when assessing water regime and associated dissolved substance transport in soils. The main aim of this contribution is to describe the temporal development of unsaturated hydraulic conductivity on arable land during a year. The experimental site is located in Nucice catchment (Central Bohemia, Czech republic), where also rainfall-runoff and soil erosion processes are studied. The soil is classified as Cambisol, typical texture ranges from loam to clay loam classes. Soil is conservatively tilled till depth of approximately 17 cm, below the topsoil a compacted subsoil was observed. Tension infiltration experiments were performed repeatedly at single location in order to determine the unsaturated hydraulic conductivity of the topsoil. So far four tension infiltration campaigns were carried out under tension h0 = -3.0 cm with different field conditions: (i) young winter barley (October 2012), (ii) between postharvest stubble breaking and seeding (April 2013), (iii) full-grown oat (June 2013) and (iv) after fresh postharvest stubble breaking (October 2013). Measurements were carried out using newly introduced automated multi minidisk tension infiltrometer (Klipa et al., EGU2014-7230). All experiments were performed on the levelled soil surface after removing upper soil layer (1 to 3 cm). A thin layer of quartz sand (thickness 1 - 2 mm, grain size 0.1 - 0.6 mm) was applied to improve contact between the infiltrometer and the soil surface. Each infiltration campaign consisted of six tension infiltration experiments, the total number of 24 infiltration data sets was obtained for this study. Results show that unsaturated hydraulic conductivity was significantly smaller in April, but rather the same in the remaining cases. Based on the monitoring of the water regime on the catchment, the infiltration capacity of the soil profile is decreasing during the season. This indicates that the hydraulic properties of the aggregates are stable. The limited infiltration is caused by the changing ratio of the inter-aggregare voids and the soil crusting (Zumr et al., EGU2014-7292). Measured data are part of a broader data base which is formed in order to the study the rainfall runoff and erosion processes on the agriculturally managed catchment.

Klípa, Vladimír; Zumr, David; Sn?hota, Michal

2014-05-01

129

Description of the unsaturated soil hydraulic database UNSODA version 2.0  

NASA Astrophysics Data System (ADS)

Quantifying water flow and chemical transport in the vadose zone typically requires knowledge of the unsaturated soil hydraulic properties. The UNsaturated SOil hydraulic DAtabase (UNSODA) was developed to provide a source of unsaturated hydraulic data and some other soil properties for practitioners and researchers. The current database contains measured soil water retention, hydraulic conductivity and water diffusivity data as well as pedological information of some 790-soil samples from around the world. A first MS-DOS version of the database was released in 1996. It has been applied in numerous studies. In this paper, we describe the second version (UNSODA V2.0) for use with Microsoft Access-97 ®. The format and structure of the new database have been modified to provide additional and more convenient options for data searches, to provide compatibility with other programs for easy loading and downloading of data, and to allow users to customise the contents and look of graphical output. This paper reviews the structure and contents of the database as well as the operations that can be performed on the different data types in UNSODA V2.0. The use and application of the new database are illustrated with two examples. The retrieval of data is briefly illustrated, followed by a more detailed example regarding the interpolation of soil particle-size distribution data obtained according to different national definitions of particle-size classes. The interpolation procedure, which is based on finding similar particle-size distribution curves from a large European data set, also performed well for soils that originate from other geographical areas. Trade names are provided for the benefit of the reader and do not imply an endorsement by the authors or their organizations.

Nemes, A.; Schaap, M. G.; Leij, F. J.; Wösten, J. H. M.

2001-10-01

130

Novel method for the simultaneous quantification of soil hydraulic functions in the laboratory under consideration of shrinkage  

NASA Astrophysics Data System (ADS)

Knowledge about the soil hydraulic properties - water retention curve and unsaturated hydraulic conductivity - is required for soil water modelling and various soil hydrological studies. In general, soils and their pore size system are assumed to be rigid during the loss of water on drying. This is different from reality for many soils, especially for soils with high contents of clay or organic matter which are shrinking dependent on the pore pressure. As a result, the porosity, the pore size distribution and the bulk density of these soils are changing. Measurements of soil hydraulic functions with the classical methods are time consuming, the equipment is costly and the measuring results are affected by uncertainties. Methods enabling the quantification of soil hydraulic functions under consideration of shrinkage are missing. A method frequently used for the simultaneous determination of both the hydraulic functions of unsaturated soil samples is the evaporation method. Due to the limited range of common tensiometers, all methodological variations of the evaporation method in the past suffered from the limitation that the hydraulic functions could only be determined to a maximum tension of 50 kPa. The extended evaporation method (EEM) overcomes this restriction. Using new boyling delay tensiometers and applying the air-entry pressure of the tensiometer's porous ceramic cup as final tension value allows the quantification of the soil hydraulic functions in a range to close to the wilting point. Based on EEM a practicable method was developed which additionally allows the consideration of shrinkage. The experimental setup followed the system HYPROP which is a commercial device with vertically aligned tensiometers that is optimized to perform evaporation measurements. Preliminary investigations were conducted to study the geometrical change of 24 samples different in texture and origin. The samples were enwrapped with a rubber membrane impermeable for water and air. The sample height and the sample circumference were detected during drying. The results confirmed (i) isotropic shrinkage and (ii) a quite linear decrease of the sample circumference from the bottom to the top of the sample. As a conclusion, for quantifying the volume change of the sample during evaporation it should be sufficient to measure the changing circumference in the middle position of the cylindrical sample. Together with the recorded tensions and the sample mass, the soil hydraulic functions could be quantified in the range between saturation and close to the permanent wilting point in consideration of shrinkage. Common soil hydraulic data models could be fitted to the soil hydraulic and shrinkage data.

Schindler, Uwe; Mueller, Lothar

2013-04-01

131

Biochar-Induced Changes in Soil Hydraulic Conductivity and Dissolved Nutrient Fluxes Constrained by Laboratory Experiments  

PubMed Central

The addition of charcoal (or biochar) to soil has significant carbon sequestration and agronomic potential, making it important to determine how this potentially large anthropogenic carbon influx will alter ecosystem functions. We used column experiments to quantify how hydrologic and nutrient-retention characteristics of three soil materials differed with biochar amendment. We compared three homogeneous soil materials (sand, organic-rich topsoil, and clay-rich Hapludert) to provide a basic understanding of biochar-soil-water interactions. On average, biochar amendment decreased saturated hydraulic conductivity (K) by 92% in sand and 67% in organic soil, but increased K by 328% in clay-rich soil. The change in K for sand was not predicted by the accompanying physical changes to the soil mixture; the sand-biochar mixture was less dense and more porous than sand without biochar. We propose two hydrologic pathways that are potential drivers for this behavior: one through the interstitial biochar-sand space and a second through pores within the biochar grains themselves. This second pathway adds to the porosity of the soil mixture; however, it likely does not add to the effective soil K due to its tortuosity and smaller pore size. Therefore, the addition of biochar can increase or decrease soil drainage, and suggests that any potential improvement of water delivery to plants is dependent on soil type, biochar amendment rate, and biochar properties. Changes in dissolved carbon (C) and nitrogen (N) fluxes also differed; with biochar increasing the C flux from organic-poor sand, decreasing it from organic-rich soils, and retaining small amounts of soil-derived N. The aromaticity of C lost from sand and clay increased, suggesting lost C was biochar-derived; though the loss accounts for only 0.05% of added biochar-C. Thus, the direction and magnitude of hydraulic, C, and N changes associated with biochar amendments are soil type (composition and particle size) dependent. PMID:25251677

Barnes, Rebecca T.; Gallagher, Morgan E.; Masiello, Caroline A.; Liu, Zuolin; Dugan, Brandon

2014-01-01

132

USE OF LIMITED SOIL PROPERTY DATA AND MODELING TO ESTIMATE ROOT ZONE SOIL WATER CONTENT.  

Technology Transfer Automated Retrieval System (TEKTRAN)

Modeling root zone soil water content at watershed scales is important for both the strategic and tactical management of water resources, but detailed soil physical and hydraulic property data required by most physically-based soil water models are generally not available over large land areas. Wit...

133

HYDRAULIC AND PHYSICAL PROPERTIES OF MCU SALTSTONE  

SciTech Connect

The Saltstone Disposal Facility (SDF), located in the Z-Area of the Savannah River Site (SRS), is used for the disposal of low-level radioactive salt solution. The SDF currently contains two vaults: Vault 1 (6 cells) and Vault 4 (12 cells). Additional disposal cells are currently in the design phase. The individual cells of the saltstone facility are filled with saltstone., Saltstone is produced by mixing the low-level radioactive salt solution, with blast furnace slag, fly ash, and cement or lime to form a dense, micro-porous, monolithic, low-level radioactive waste form. The saltstone is pumped into the disposal cells where it subsequently solidifies. Significant effort has been undertaken to accurately model the movement of water and contaminants through the facility. Key to this effort is an accurate understanding of the hydraulic and physical properties of the solidified saltstone. To date, limited testing has been conducted to characterize the saltstone. The primary focus of this task was to estimate the hydraulic and physical properties of MCU (Modular Caustic Side Solvent Extraction Unit) saltstone relative to two permeating fluids. These fluids included simulated groundwater equilibrated with vault concrete and simulated saltstone pore fluid. Samples of the MCU saltstone were prepared by the Savannah River National Laboratory (SRNL) and allowed to cure for twenty eight days prior to testing. These samples included two three-inch diameter by six inch long mold samples and three one-inch diameter by twelve inch long mold samples.

Dixon, K; Mark Phifer, M

2008-03-19

134

Consequences of varied soil hydraulic and meteorological complexity on unsaturated zone time lag estimates  

NASA Astrophysics Data System (ADS)

The true efficacy of a programme of agricultural mitigation measures within a catchment to improve water quality can be determined only after a certain hydrologic time lag period (subsequent to implementation) has elapsed. As the biophysical response to policy is not synchronous, accurate estimates of total time lag (unsaturated and saturated) become critical to manage the expectations of policy makers. The estimation of the vertical unsaturated zone component of time lag is vital as it indicates early trends (initial breakthrough), bulk (centre of mass) and total (Exit) travel times. Typically, estimation of time lag through the unsaturated zone is poor, due to the lack of site specific soil physical data, or by assuming saturated conditions. Numerical models (e.g. Hydrus 1D) enable estimates of time lag with varied levels of input data. The current study examines the consequences of varied soil hydraulic and meteorological complexity on unsaturated zone time lag estimates using simulated and actual soil profiles. Results indicated that: greater temporal resolution (from daily to hourly) of meteorological data was more critical as the saturated hydraulic conductivity of the soil decreased; high clay content soils failed to converge reflecting prevalence of lateral component as a contaminant pathway; elucidation of soil hydraulic properties was influenced by the complexity of soil physical data employed (textural menu, ROSETTA, full and partial soil water characteristic curves), which consequently affected time lag ranges; as the importance of the unsaturated zone increases with respect to total travel times the requirements for high complexity/resolution input data become greater. The methodology presented herein demonstrates that decisions made regarding input data and landscape position will have consequences for the estimated range of vertical travel times. Insufficiencies or inaccuracies regarding such input data can therefore mislead policy makers regarding the achievability of water quality targets.

Vero, S. E.; Ibrahim, T. G.; Creamer, R. E.; Grant, J.; Healy, M. G.; Henry, T.; Kramers, G.; Richards, K. G.; Fenton, O.

2014-12-01

135

Consequences of varied soil hydraulic and meteorological complexity on unsaturated zone time lag estimates.  

PubMed

The true efficacy of a programme of agricultural mitigation measures within a catchment to improve water quality can be determined only after a certain hydrologic time lag period (subsequent to implementation) has elapsed. As the biophysical response to policy is not synchronous, accurate estimates of total time lag (unsaturated and saturated) become critical to manage the expectations of policy makers. The estimation of the vertical unsaturated zone component of time lag is vital as it indicates early trends (initial breakthrough), bulk (centre of mass) and total (Exit) travel times. Typically, estimation of time lag through the unsaturated zone is poor, due to the lack of site specific soil physical data, or by assuming saturated conditions. Numerical models (e.g. Hydrus 1D) enable estimates of time lag with varied levels of input data. The current study examines the consequences of varied soil hydraulic and meteorological complexity on unsaturated zone time lag estimates using simulated and actual soil profiles. Results indicated that: greater temporal resolution (from daily to hourly) of meteorological data was more critical as the saturated hydraulic conductivity of the soil decreased; high clay content soils failed to converge reflecting prevalence of lateral component as a contaminant pathway; elucidation of soil hydraulic properties was influenced by the complexity of soil physical data employed (textural menu, ROSETTA, full and partial soil water characteristic curves), which consequently affected time lag ranges; as the importance of the unsaturated zone increases with respect to total travel times the requirements for high complexity/resolution input data become greater. The methodology presented herein demonstrates that decisions made regarding input data and landscape position will have consequences for the estimated range of vertical travel times. Insufficiencies or inaccuracies regarding such input data can therefore mislead policy makers regarding the achievability of water quality targets. PMID:25444116

Vero, S E; Ibrahim, T G; Creamer, R E; Grant, J; Healy, M G; Henry, T; Kramers, G; Richards, K G; Fenton, O

2014-12-01

136

Atlas of soil reflectance properties  

NASA Technical Reports Server (NTRS)

A compendium of soil spectral reflectance curves together with soil test results and site information is presented in an abbreviated manner listing those soil properties most important in influencing soil reflectance. Results are presented for 251 soils from 39 states and Brazil. A narrative key describes relationships between soil parameters and reflectance curves. All soils are classified according to the U.S. soil taxonomy and soil series name for ease of identification.

Stoner, E. R.; Baumgardner, M. F.; Biehl, L. L.; Robinson, B. F.

1979-01-01

137

Rapid estimation of topsoil hydraulic properties from coupled inversion of TDR data during falling head infiltration  

NASA Astrophysics Data System (ADS)

Fast and accurate estimation of topsoil hydraulic properties is very important in many environmental and engineering fields of study. On a small scale, one way of estimating these properties is to monitor infiltration of water into the soil with time domain reflectometry (TDR). Traditionally, TDR data collected during infiltration events are initially converted into average water content along the length of the TDR probe using travel time techniques. These water content averages are then used to inversely estimate soil hydraulic properties by calibrating a hydraulic model or an analytical solution of Richard’s equation describing the infiltration event. However, travel time analysis is subjective and difficult to use for interpretation of TDR measurements made during infiltration events. Moreover, all the errors made in converting the TDR data into water content averages directly propagate to the estimated hydraulic properties. In this study, we examine a new approach to estimating topsoil hydraulic properties from TDR data collected during falling head infiltration. Unlike the classical travel-time based approach to interpreting TDR, we interpret TDR measurements based on inverse modeling of TDR waveforms which has the potential to retrieve spatially resolved soil dielectric permittivity profiles. Instead of using TDR-inferred water content averages as in the traditional approach, we directly use the TDR waveforms to estimate soil properties. This was achieved by coupling a forward model of TDR waveform propagation to a hydrological model describing falling head infiltration. By perturbing the hydraulic parameters in the hydrological model, water content profiles are simulated and converted to TDR waveforms using the TDR forward model. This is repeated until a close fit between measured and modeled TDR waveforms is found. Apart from its potential to provide accurate and hydrologically relevant estimates of topsoil hydraulic properties, the coupled approach also enables accurate estimation of the depths of ponded water at the soil surface. Accurate monitoring of ponded depths of water is important for many applications, including flood irrigation management and flood control by earth dams. Moreover as it is not necessary to manually measure the ponding depths, the coupled approach offers the possibility of automatic monitoring of falling head infiltration at several rings at several locations in the field based on TDR multiplexing. This can lead to rapid and cost effective estimation of topsoil hydraulic properties.

Mboh, C.; Huisman, J. A.; Vereecken, H.

2010-12-01

138

Determination of till hydraulic properties for modelling flow and solute transport in a forested hillslope  

NASA Astrophysics Data System (ADS)

Shallow till layers typically overlay bedrock in forested areas in the boreal region. In forested tills, preferential flowpaths related to the soil structure have a decisive influence on hydrogeological properties such as the soil hydraulic conductivity. Hydraulic conductivity is also proven to depend on the observation scale. Traditional soil core samples cannot capture the impact of soil structure on hillslope scale conductivities. Measurements and observations made at different scales, combined with simulation models, are essential for investigating conductivity properties and flow and transport processes in forest soils. This study combined a set of soil analyses and field experiments with physics-based modelling to investigate the hydraulic properties of a forested till slope in Finland. The main objective was to i) determine the saturated hydraulic conductivity in the study slope with methods related to different scales, and to ii) study the utilisation of the conductivity results in modelling flow and solute transport in the slope. Soil sampling, dye, and ion tracer experiments were conducted in a forested hillslope in Eastern Finland. In the 20 m long study section of the slope the mean slope was about 15 %. The haplic podsol profile above bedrock had a thickness of 0.8 m and was formed of sandy till. The soil was very stony and heterogeneous in terms of granularity and pore size distribution. Granularity, porosity and proportion of macropores reduced clearly with depth. Dye tracer experiments revealed three types of preferential flow routes in the slope: i) stone surfaces, ii) areas of coarse-grained soil material, and iii) decayed root channels. Both living roots and preferential flowpaths reached the transitional zone of the podsol at about 0.5 m depth, but living roots were not found to function unequivocally as preferential flowpaths. The saturated hydraulic conductivity was determined using three methods: i) from soil core samples in laboratory, ii) with Guelph permeameter in the field, iii) and by means of inverse modelling. The inverse model application was based on calibration of a one-dimensional groundwater model against data on groundwater levels in the study slope. Conductivities of the different soil horizons were adjusted to reproduce the measured groundwater levels of a recession period after artificial irrigation. Conductivity results, together with soil physical and water retention data were applied to parameterise a three-dimensional flow and advection-dispersion model. The model was used to simulate the transport of a chloride tracer plume in the study slope during artificial irrigation. A line-type irrigation source was installed upslope from the study section of the slope. Changes in groundwater levels and chloride concentrations within the study section were observed through well screens. Chloride as a conservative tracer provided an indicator for subsurface flow in the study slope. Intensive irrigation rates were applied to initiate fast lateral preferential flow. Saturated hydraulic conductivities obtained with the three methods were remarkably different. Conductivities obtained with the Guelph permeameter and the groundwater model reduced clearly with soil depth. Higher conductivities near soil surface were due to loose soil structure and preferential flowpaths. Soil core samples yielded the lowest estimates for the saturated hydraulic conductivity, as they represented the small-scale conductivity of the soil texture and soil matrix. The hillslope-scale groundwater model produced the highest estimates that characterised the large-scale structural properties and their impact on lateral preferential flow. Average saturated hydraulic conductivities in the soil core samples were 6E-6 m/s in the eluvial horizon, transition zone and subsoil, and 1E-5 m/s in the illuvial horizon. The average conductivities based on the Guelph measurements varied from 2E-5 m/s in the subsoil to 5E-5 m/s in the eluvial horizon, and based on the groundwater model from 6E-5 m/s in the subsoil to 3E-4 m/s in the elu

Laine-Kaulio, H.; Karvonen, T.; Koivusalo, H.; Lauren, A.; Saastamoinen, S.

2009-04-01

139

Scale-dependency of the hydraulic properties of a variably saturated heterogeneous sandy subsoil  

NASA Astrophysics Data System (ADS)

SummaryThe effective hydraulic behaviour of heterogeneous sand was experimentally investigated at two scales under transient flow upper boundary conditions. At the monoliths-scale, one-dimensional inverse modelling was performed from a transient infiltration experiment by implementing in the objective function the outflow and pressure head time series at four depths. Notwithstanding the important heterogeneity of the subsoil, principally due to the presence of discontinuous clay and a stone layer, we observed that the effective behaviour was surprisingly well reproduced. It was also observed that the structural features mainly induced a kind of hysteresis between the saturation and drainage cycles of the outflow time series. Subsequently, 104 Kopecky cores (100 cm 3) were sub-sampled throughout the monolith, mainly in the sandy matrix. The variability of local hydraulic parameters was investigated by optimising the local hydraulic parameters from multi-step outflow experiments and measured retention points. The comparison between 1-D optimised, measured and Kopecky-averaged retention curves showed relatively similar shape near saturation. In contrast to this, important discrepancies existed between averaged local scale hydraulic conductivity and effective hydraulic conductivity close to saturation. Different experimental designs at different scales may explain the observed discrepancies. It is further suggested that the monolith-scale effective hydraulic functions are more representative for wet soil conditions. This case study illustrates the complexity of finding validated scaling relationships for the hydraulic properties of heterogeneous soils at scales larger than the usual small column scale.

Javaux, M.; Vanclooster, M.

2006-08-01

140

Determination of the hydraulic characteristics of unsaturated soils using a centrifuge permeameter.  

E-print Network

??A new experimental approach to determine the hydraulic characteristics of unsaturated soils using a centrifuge permeameter was developed in this study. Specifically, the centrifuge permeameter… (more)

McCartney, John Scott, 1979-

2008-01-01

141

Application of EM38 and ERT methods in estimation of saturated hydraulic conductivity in unsaturated soil  

NASA Astrophysics Data System (ADS)

Soil apparent electrical conductivity is being considerably used as a surrogate measure for soil properties and hydraulic parameters. In this study, measurements of electrical conductivity were accomplished with electrical resistivity tomography (ERT) and EM38 to develop multiple datasets for defining spatiotemporal moisture content variations and estimating saturated hydraulic conductivity under natural conditions in an experimental site located in Lisbon, Portugal. In addition, EM38 capability in monitoring electrical conductivity variations in comparison with ERT method was examined. In order to achieve these objectives, appropriate relationships were derived based on determination of experimental curve resistivity vs. degree of saturation by in-situ investigation to convert electrical resistivity maps inferred from ERT and EM38 data to moisture content distribution maps. In addition, the surface temperature variations during the experiment were measured and the effects of the temperature variations were removed by assuming 2% change in electrical resistivity per °C change in temperature. The conducted experiment proves that the soil is fairly homogenous and semi-pervious sediment and the spatiotemporal moisture content variations during the experiment barely exceed 10%. Our calculations constrain the range of saturated hydraulic conductivity to be 3-9 (cm/day) range.

Farzamian, Mohammad; Monteiro Santos, Fernando A.; Khalil, Mohamed A.

2015-01-01

142

Gas diffusion-derived tortuosity governs saturated hydraulic conductivity in sandy soils  

NASA Astrophysics Data System (ADS)

The saturated hydraulic conductivity (Ksat) is an essential effective parameter for the development of improved distributed hydrological models and area-differentiated risk assessment of chemical leaching. Basic soil properties such as the particle size distribution or, more recently, air permeability are commonly used to estimate Ksat. Conversely, links to soil gas diffusivity (Dp/Do) have not been fully explored even though gas diffusivity is intimately linked to the connectivity and tortuosity of the soil pore network. Based on measurements for a coarse sandy soil, potential relationships between Ksat and Dp/Do were investigated. A total of 84 undisturbed soil cores were extracted from the topsoil of a field site, and Dp/Do and Ksat were measured in the laboratory. Water-induced and solids-induced tortuosity factors were obtained by applying a two-parameter Dp/Do model to measured data, and subsequently linked to the cementation exponent of the well-established Revil and Cathles predictive model for saturated hydraulic conductivity. Furthermore, a two-parameter model, analogue to the Kozeny-Carman equation, was developed for the Ksat - Dp/Do relationship. All analyses implied strong and fundamental relationships between Ksat and Dp/Do.

Masís-Meléndez, Federico; Chamindu Deepagoda, T. K. K.; de Jonge, Lis Wollesen; Tuller, Markus; Moldrup, Per

2014-05-01

143

High-resolution hydraulic parameter maps for surface soils in tropical South America  

NASA Astrophysics Data System (ADS)

Modern land surface model simulations capture soil profile water movement through the use of soil hydraulics sub-models, but good hydraulic parameterisations are often lacking, especially in the tropics. We present much-improved gridded data sets of hydraulic parameters for surface soil for the critical area of tropical South America, describing soil profile water movement across the region to 30 cm depth. Optimal hydraulic parameter values are given for the Brooks and Corey, Campbell, van Genuchten-Mualem and van Genuchten-Burdine soil hydraulic models, which are widely used hydraulic sub-models in land surface models. This has been possible through interpolating soil measurements from several sources through the SOTERLAC soil and terrain data base and using the most recent pedotransfer functions (PTFs) derived for South American soils. All soil parameter data layers are provided at 15 arcsec resolution and available for download, this being 20x higher resolution than the best comparable parameter maps available to date. Specific examples are given of the use of PTFs and the importance highlighted of using PTFs that have been locally parameterised and that are not just based on soil texture. We discuss current developments in soil hydraulic modelling and how high-resolution parameter maps such as these can improve the simulation of vegetation development and productivity in land surface models.

Marthews, T. R.; Quesada, C. A.; Galbraith, D. R.; Malhi, Y.; Mullins, C. E.; Hodnett, M. G.; Dharssi, I.

2014-05-01

144

High-resolution hydraulic parameter maps for surface soils in tropical South America  

NASA Astrophysics Data System (ADS)

Modern land surface model simulations capture soil profile water movement through the use of soil hydraulics sub-models, but good hydraulic parameterisations are often lacking, especially in the tropics. We present much-improved gridded datasets of hydraulic parameters for surface soil for the critical area of tropical South America, describing soil profile water movement across the region to 30 cm depth. Optimal hydraulic parameter values are given for the Brooks and Corey, Campbell, van Genuchten-Mualem and van Genuchten-Burdine soil hydraulic models, which are widely-used hydraulic sub-models in Land Surface Models. This has been possible through interpolating soil measurements from several sources through the SOTERLAC soil and terrain database and using the most recent pedotransfer functions (PTFs) derived for South American soils. All soil parameter data layers are provided at 15 arcsec resolution and available for download, this being 20 × higher resolution than the best comparable parameter maps available to date. Specific examples are given of the use of PTFs and the importance highlighted of using PTFs that have been locally-parameterised and that are not just based on soil texture. Details are provided specifically on how to assemble the ancillary data files required for grid-based vegetation simulation using the Joint UK Land Environment Simulator (JULES). We discuss current developments in soil hydraulic modelling and how high-resolution parameter maps such as these can improve the simulation of vegetation development and productivity in land surface models.

Marthews, T. R.; Quesada, C. A.; Galbraith, D. R.; Malhi, Y.; Mullins, C. E.; Hodnett, M. G.; Dharssi, I.

2013-12-01

145

Water repellency in an Alpine forest soil and its impact on hydraulic characteristics under simulated climate change  

NASA Astrophysics Data System (ADS)

The climate of Alpine environments is expected to change dramatically as a consequence of global climate change. In this ecologically sensitive environment, prolonged dry periods and an increased occurence of extreme rainfall events is forecasted by many climate change models. On the other hand, soil water repellency (SWR) is known to affect hydraulic processes in soils, particularly in acidic forest soils and as a consequence of prolonged dry periods. By changing the soil surface properties, SWR also changes the hydraulically effective properties of soils. The quantification of the spatial occurence and degree of hydrophobicity is a crucial prerequirement for ecological and hydrological impact assessment and developing new models. Therefore, the objective of the present study was to quantify soil water repellency in an Alpine forest with respect to its spatial variability and affected by different simulated climatic regimes. The study was accomplished in the Rosalian mountains, some 60 km south of Vienna, Austria. The vegetation was a mature beech forest and the soil was a Podsolic Cambisol over weathered granitic rock debris. As parts of the experimental plot were covered by plastic roofs and artificially irrigated, three different treatments were tested: Compared to the natural precipitation (control), the irrigation amount was reduced with two drought degrees (moderate and extreme). Within a small grid, 9 samples were taken per treatment in two depths (surface and 0.10 m). The contact angle was determined with the modified sessile drop method. Additionally, total and organic carbon contents and the hydraulic soil properties were quantified. Infiltration experiments were performed with a tension infiltrometer using water and ethanol. The results showed considerable water repellency with at least subcritical contact angles for all treatments. Contact angles increased to above 90 degree at the moderate and extreme drought treatments. Differences between intrinsic and apparent hydraulic properties as reflected by the ethanol and water infiltration, respectively, increased with increasing drought degree.

Schwen, Andreas; Zimmermann, Michael; Lamparter, Axel; Woche, Susanne; Bachmann, Jörg

2014-05-01

146

EFFECTS OF ELECTROOSMOSIS ON SOIL TEMPERATURE AND HYDRAULIC HEAD: II. NUMERICAL SIMULATION  

EPA Science Inventory

A numerical model to simulate the distributions of voltage, soil temperature, and hydraulic head during the field test of electroosmosis was developed. The two-dimensional governing equations for the distributions of voltage, soil temperature, and hydraulic head within a cylindri...

147

Hydraulic properties of adsorbed water films in unsaturated porous media  

SciTech Connect

Adsorbed water films strongly influence residual water saturations and hydraulic conductivities in porous media at low saturations. Hydraulic properties of adsorbed water films in unsaturated porous media were investigated through combining Langmuir's film model with scaling analysis, without use of any adjustable parameters. Diffuse double layer influences are predicted to be important through the strong dependence of adsorbed water film thickness (f) on matric potential ({Psi}) and ion charge (z). Film thickness, film velocity, and unsaturated hydraulic conductivity are predicted to vary with z{sup -1}, z{sup -2}, and z{sup -3}, respectively. In monodisperse granular media, the characteristic grain size ({lambda}) controls film hydraulics through {lambda}{sup -1} scaling of (1) the perimeter length per unit cross sectional area over which films occur, (2) the critical matric potential ({Psi}{sub c}) below which films control flow, and (3) the magnitude of the unsaturated hydraulic conductivity when {Psi} < {Psi}{sub c}. While it is recognized that finer textured sediments have higher unsaturated hydraulic conductivities than coarser sands at intermediate {Psi}, the {lambda}{sup -1} scaling of hydraulic conductivity predicted here extends this understanding to very low saturations where all pores are drained. Extremely low unsaturated hydraulic conductivities are predicted under adsorbed film-controlled conditions (generally < 0.1 mm y{sup -1}). On flat surfaces, the film hydraulic diffusivity is shown to be constant (invariant with respect to {Psi}).

Tokunaga, Tetsu K.

2009-03-01

148

Soils - Part 2: Physical Properties of Soil and Soil Water  

NSDL National Science Digital Library

This lesson will help you understand the major components of the physical properties of soil. You will learn such terms as texture, aggregation, soil structure, bulk density, and porosity as it relates to soils. You will learn how soil holds and transmits water and cultural practices that enhance or degrade physical properties of the soil.[This lesson, as well as the other nine lessons in the Soils series, is taken from the "Soils Home Study Course," published in 1999 by the University of Nebraska Cooperative Extension.

149

Transport Properties of Soils and Spectral Electrical Response: Equivalent Circuit Models  

NASA Astrophysics Data System (ADS)

Non-invasive prediction of hydraulic properties of soils (hydraulic conductivity, porosity, and degree of saturation) from surface measurement techniques as provided by geophysical methods is appealing to geoscientists involved in groundwater and pollution control problems. There is the need, however, to understand how the hydraulic properties of soil influence their spectral electrical response (SER). Laboratory measurements of the spectral electrical response of over 30 soil samples taken from different sites across North Carolina were performed within the frequency range from 0.01 Hz to 10 kHz. The hydraulic conductivity, porosity, and moisture content of each soil sample were measured. Both the moisture content and the degree of compaction were controlled for each soil sample to simulate field conditions. The SER measurements are used to estimate the hydraulic conductivity and porosity of soils. The SER of a soil is modeled as a heterogeneous multiphase system using an equivalent circuit model. The intrinsic parameters, which describe the response of the model, are retrieved by an inversion scheme and are used in empirical regression models to predict the hydraulic conductivity and porosity. Multiple regression analyses suggest that the porosity and permeability can be well predicted by the parameters of the equivalent circuit model. Such direct relationships between parameters characterizing the spectral electrical response of soils and their hydraulic properties may provide versatile non-invasive methodology of obtaining hydraulic conductivity and porosity of soils using geophysical measurements.

Boadu, F. K.

2002-05-01

150

Hydraulics.  

ERIC Educational Resources Information Center

This curriculum guide contains a course in hydraulics to train entry-level workers for automotive mechanics and other fields that utilize hydraulics. The module contains 14 instructional units that cover the following topics: (1) introduction to hydraulics; (2) fundamentals of hydraulics; (3) reservoirs; (4) lines, fittings, and couplers; (5)…

Decker, Robert L.; Kirby, Klane

151

HYDRAULIC CONDUCTIVITY ESTIMATION IN PARTIALLY SATURATED SOILS USING THE ADJOINT METHOD  

E-print Network

-term changes in soil moisture stores have been identified as an indica- tor of climate change, and soil for the estimation of the saturated hydraulic conductivity k in a partially saturated soil Q is proposed. Groundwater, understanding and quantifying the global hy- drologic cycle has become a priority research. Soil moisture

Efendiev, Yalchin

152

Vadose-zone monitoring strategy to evaluate desalted groundwater effects on hydraulic properties  

NASA Astrophysics Data System (ADS)

Desalinated brackish groundwater is becoming a new source of water supply to comply with growing water demands, especially in (semi) arid countries. Irrigation with desalinated or a blend of desalinated and ground/surface water, presents associated impacts on plants, soil and aquifer media. Mixed waters with different salinities can lead to the formation of unexpected chemical precipitates. The use of desalted groundwater for irrigation counts with potential drawbacks, among them: changes of hydraulic properties of soil-aquifer systems (e.g. hydraulic conductivity, porosity) as a consequence of mineral precipitation; root growth blockage and plant uptake of pollutants; as well as leaching of contaminants to groundwater. An experimental plot located at SE Spain, covered by grass and irrigated by sprinklers with a blend of desalted and groundwater from a brackish aquifer, has been monitored in order to characterize at field scale the possible impacts on soil hydraulic properties. The monitoring strategy to control water and heat flux includes traditional and more updated devices. The field instrumentation, vertically installed from the ground surface and spatially distributed, consisted of: ten tensiometers (Soilmoisture Equipment Corp, Goleta, CA, USA) at different depths (two per depth); and, two access tubes (fiber glass, 44mm diameter 2m length) for soil moisture measurements from TRIME-FM TDR probe (Imko GmbH, Ettlingen, Germany). Automatic logging is carried out from a trench located in the border of the experimental plot and it takes in: a set of five 5TE devices (Decagon Devices Inc, Pullman, WA, USA) vertically installed, which measure volumetric water content, electric conductivity and temperature; and additionally, a suction sensor at 0.6m depth. Finally, a periodic sampling of undisturbed soil cores (2m length) takes place for the purpose of imaging porosity changes from environmental scanning electron microscope (ESEM). First results about water and heat flux, as well as changes in the soil hydraulic properties, are presented in the current work.

Valdes-Abellan, J.; Candela, L.; Jiménez-Martínez, J.

2012-04-01

153

Agricultural soil moisture experiment, Colby, Kansas 1978: Measured and predicted hydrological properties of the soil  

NASA Technical Reports Server (NTRS)

Predictive procedures for developing soil hydrologic properties (i.e., relationships of soil water pressure and hydraulic conductivity to soil water content) are presented. Three models of the soil water pressure-water content relationship and one model of the hydraulic conductivity-water content relationship are discussed. Input requirements for the models are indicated, and computational procedures are outlined. Computed hydrologic properties for Keith silt loam, a soil typer near Colby, Kansas, on which the 1978 Agricultural Soil Moisture Experiment was conducted, are presented. A comparison of computed results with experimental data in the dry range shows that analytical models utilizing a few basic hydrophysical parameters can produce satisfactory data for large-scale applications.

Arya, L. M. (principal investigator)

1980-01-01

154

Characterization of the hydraulic properties of fractures in chalk.  

PubMed

The fracture systems intersecting Eocene chalk formations in the Negev desert, Israel, and their hydraulic properties were characterized using a variety of geologic and hydrologic techniques. These included identification of the prevailing directions of fracture systems in outcrops, in cores retrieved from inclined coreholes, in coreholes using video logs, and in trenches. The orientation and inclination of these fracture systems were determined, and evidence of ground water flow on the fracture surfaces was described and ranked. Their hydraulic conductivity was determined through slug and pumping tests performed at discrete intervals. Temperature, electrical conductivity, caliper, gamma and heat-pulse logs were conducted in the same coreholes. The results from the logs, tests, and core descriptions were compared to identify reliable and cost-effective tools for investigating the hydraulic characteristics of fracture systems. We concluded that in the study area: (1) fracture mapping in outcrops and coreholes (including downhole video and caliper logs) must be supplemented by hydraulic testing of the mapped fracture sets in the coreholes; (2) inclined coreholes provide information regarding the orientation of the hydraulically active fracture systems that cannot be obtained from vertical boreholes; (3) hydraulic testing of unpacked holes provides a reasonable estimate of the maximum hydraulic conductivity; and (4) the hydraulic conductivity distribution with depth is log normal and all significant ground water flow takes place within the upper 25 m. PMID:12873016

Nativ, Ronit; Adar, Eilon; Assaf, Lior; Nygaard, Erik

2003-01-01

155

Development of Property-Transfer Models for Estimating the Hydraulic Properties of Deep  

E-print Network

Development of Property-Transfer Models for Estimating the Hydraulic Properties of Deep Sediments. #12;Development of Property-Transfer Models for Estimating the Hydraulic Properties of Deep Sediments-USGS World Wide Web: http://www.usgs.gov/ Any use of trade, product, or firm names in this publication

156

Comparison of Aquifer Recharge Estimates Based on Measured and Estimated Hydraulic Properties  

NASA Astrophysics Data System (ADS)

Because unsaturated hydraulic properties, which are used to estimate recharge, are difficult and time consuming to measure accurately, models that estimate these properties indirectly are often used. Using data from six locations in southern New Jersey that appear to have steady-state flow conditions, five hydraulic property prediction and parameterization techniques were evaluated for recharge estimation. The unsaturated zone at this site, as in many coastal plain regions, is mainly sand to sandy loam in texture, which is considered a highly favorable case for soil hydraulic property estimation. Annual recharge has been estimated for several southern New Jersey watersheds by water budget methods and ranges from 33 to 49 cm/yr. Using these estimates as a gauge of reasonable values for steady flow, several indirect methods were compared to determine which are appropriate for recharge estimation in the coastal plain environment. The methods used in this study were: (1) simple power-law and hand-drawn curve fits to measured unsaturated hydraulic conductivity, (2) measured water retention and measured unsaturated hydraulic conductivity fit using the van Genuchten-Mualem model with fixed and optimized parameter values, (3) unsaturated hydraulic conductivity estimated from measured water retention with fixed and optimized parameter values, (4) estimation of water retention and hydraulic conductivity from bulk density and minimal textural information using the Rosetta pedotransfer function model, and (5) estimation of water retention and hydraulic conductivity using high resolution particle size distributions with the Arya-Paris and van Genuchten-Mualem models. Preliminary results show that while reasonable estimates can come from directly measured unsaturated hydraulic conductivity, the curve fitting method is critical because of the extreme non-linearity of the relationship between hydraulic conductivity and water content. Even a relatively good visual fit can lead to unreasonable recharge estimation values. A hand-drawn interpolation technique, and in some cases a simple power-law fit, yielded better results for these data than the van Genuchten-Mualem curve fit. In all cases, the Rosetta model lead to unreasonably high recharge estimates, primarily due to the over-prediction of saturated hydraulic conductivity. Water retention was predicted relatively well by the Rosetta Model. A combination of the Arya-Paris and van Genuchten-Mualem models also lead to over-prediction of recharge rates, and did not do as well as Rosetta in predicting water retention for this sandy material.

Perkins, K. S.

2003-12-01

157

Soil hydraulic manipulation and organic amendment for the enhancement of selenium volatilization in a soil–pickleweed system  

Microsoft Academic Search

Biological volatilization of selenium (Se) in contaminated areas represents an environmentally friendly phytoremediation approach. Implementation of phytovolatilization technology for the remediation of Se-contaminated soils or sediments is oftentimes limited by its low remediation efficiency under field conditions. This greenhouse study determined the feasibility of manipulating soil organic content and hydraulic conditions in a soil–pickleweed (Salicornia bigelovii) system for the enhancement

B. Shrestha; S. Lipe; K. A. Johnson; T. Q. Zhang; W. Retzlaff; Z.-Q. Lin

2006-01-01

158

Hydraulics.  

ERIC Educational Resources Information Center

These instructional materials provide an orientation to hydraulics for use at the postsecondary level. The first of 12 sections presents an introduction to hydraulics, including discussion of principles of liquids, definitions, liquid flow, the two types of hydraulic fluids, pressure gauges, and strainers and filters. The second section identifies…

Engelbrecht, Nancy; And Others

159

Comparison of Laboratory and Field Methods for Determining the Quasi-Saturated Hydraulic Conductivity of Soils  

SciTech Connect

Laboratory and field ponded infiltration tests in quasi-saturated soils (containing entrapped air) exhibit the same three-stage temporal variability for the flow rate and hydraulic conductivity. However, the values for the hydraulic conductivity may differ by as much as two orders of magnitude due to differences in the geometry and physics of flow when different laboratory and field methods are applied. The purpose of this paper is to investigate this variability using a comparison of results of ponded infiltration tests conducted under laboratory conditions using confined cores, with results of field tests conducted using partially isolated cores and double-ring infiltrometers. Under laboratory conditions in confined cores, during the firs stage, the water flux decreases over time because entrapped air plugs the largest pores in the soils; during the second stage, the quasi-saturated hydraulic conductivity increases by one to two orders of magnitude, essentially reaching the saturated hydraulic conductivity, when entrapped air is discharged from the soils; during the third stage, the hydraulic conductivity decreases to minimum values due to sealing of the soil surface and the effect of biofilms sealing the pores within the wetted zone. Under field conditions, the second stage is only partially developed, and when the surface sealing process begins, the hydraulic pressure drops below the air entry value, thereby causing atmospheric air to enter the soils. As a result, the soils become unsaturated with a low hydraulic conductivity, and the infiltration rate consequently decreases. Contrary to the laboratory experiments in confined cores, the saturated hydraulic conductivity cannot be reached under field conditions. In computations of infiltration one has to take into account the variations in the quasi-saturated and unsaturated hydraulic conductivities, moisture and entrapped air content, and the hydraulic gradient in the quasi-saturated or unsaturated soils.

Faybishenko, Boris

1997-08-01

160

HYDRAULIC REDISTRIBUTION OF SOIL WATER: ECOSYSTEM IMPLICATIONS FOR PACIFIC NORTHWEST FORESTS  

EPA Science Inventory

The physical process of hydraulic redistribution (HR) is driven by competing soil, tree and atmospheric water potential gradients, and may delay severe water stress for roots and other biota associated with the upper soil profile. We monitored soil moisture characteristics across...

161

Soil Water Sensor Needs for the Evaluation of Hydraulic Lift in Crop Plants  

Technology Transfer Automated Retrieval System (TEKTRAN)

Hydraulic lift (HL) in plants is defined as the process by which water is redistributed from wet soil zones to drier soil zones through the plant root system in response to gradients in water potential. Water is released into the dry soil when plant transpiration is low (night) and reabsorbed by th...

162

HYDRAULIC REDISTRIBUTION OF SOIL WATER DURING SUMMER DROUGHT IN TWO CONTRASTING PACIFIC NORTHWEST CONIFEROUS FORESTS  

EPA Science Inventory

The magnitude of hydraulic redistribution of soil water by roots and its impact on soil water balance were estimated by monitoring time courses of soil water status at multiple depths and root sap flow during droughted conditions in a dry ponderosa pine ecosystem and a moist Doug...

163

Effects of model layer simplification using composite hydraulic properties  

USGS Publications Warehouse

The effects of simplifying hydraulic property layering within an unconfined aquifer and the underlying confining unit were assessed. The hydraulic properties of lithologic units within the unconfined aquifer and confining unit were computed by analyzing the aquifer-test data using radial, axisymmetric two-dimensional (2D) flow. Time-varying recharge to the unconfined aquifer and pumping from the confined Upper Floridan aquifer (USA) were simulated using 3D flow. Conceptual flow models were developed by gradually reducing the number of lithologic units in the unconfined aquifer and confining unit by calculating composite hydraulic properties for the simplified lithologic units. Composite hydraulic properties were calculated using either thickness-weighted averages or inverse modeling using regression-based parameter estimation. No significant residuals were simulated when all lithologic units comprising the unconfined aquifer were simulated as one layer. The largest residuals occurred when the unconfined aquifer and confining unit were aggregated into a single layer (quasi-3D), with residuals over 100% for the leakage rates to the confined aquifer and the heads in the confining unit. Residuals increased with contrasts in vertical hydraulic conductivity between the unconfined aquifer and confining unit. Residuals increased when the constant-head boundary at the bottom of the Upper Floridan aquifer was replaced with a no-flow boundary.

Sepulveda, Nicasio; Kuniansky, Eve L.

2010-01-01

164

Coevolution of hydraulic, soil and vegetation processes in estuarine wetlands  

NASA Astrophysics Data System (ADS)

Estuarine wetlands of south eastern Australia, typically display a vegetation zonation with a sequence mudflats - mangrove forest - saltmarsh plains from the seaward margin and up the topographic gradient. Estuarine wetlands are among the most productive ecosystems in the world, providing unique habitats for fish and many terrestrial species. They also have a carbon sequestration capacity that surpasess terrestrial forest. Estuarine wetlands respond to sea-level rise by vertical accretion and horizontal landward migration, in order to maintain their position in the tidal frame. In situations in which buffer areas for landward migration are not available, saltmarsh can be lost due to mangrove encroachment. As a result of mangrove invasion associated in part with raising estuary water levels and urbanisation, coastal saltmarsh in parts of south-eastern Australia has been declared an endangered ecological community. Predicting estuarine wetlands response to sea-level rise requires modelling the coevolving dynamics of water flow, soil and vegetation. This paper presents preliminary results of our recently developed numerical model for wetland dynamics in wetlands of the Hunter estuary of NSW. The model simulates continuous tidal inflow into the wetland, and accounts for the effect of varying vegetation types on flow resistance. Coevolution effects appear as vegetation types are updated based on their preference to prevailing hydrodynamic conditions. The model also considers that accretion values vary with vegetation type. Simulations are driven using local information collected over several years, which includes estuary water levels, accretion rates, soil carbon content, flow resistance and vegetation preference to hydraulic conditions. Model results predict further saltmarsh loss under current conditions of moderate increase of estuary water levels.

Trivisonno, Franco; Rodriguez, Jose F.; Riccardi, Gerardo; Saco, Patricia; Stenta, Hernan

2014-05-01

165

An analysis of selected factors controlling or affecting the hydraulic conductivity of compacted soil liners  

E-print Network

AN ANALYSIS OF SELECTED FACTORS CONTROLLING OR AFFECTING THE HYDRAULIC CONDUCTIVITY OF COMPACTED SOIL LINERS A Thesis by ROBERT CARY SPEAKE, JR. Submitted to the Graduate College of Texas ASM University in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE December 19B6 Major Subject: Civil Engineering AM ANALYSIS OF SELECTED FACTORS CONTROLLING OR AFFECTING THE HYDRAULIC CONDUCTIVITY OF COMPACTED SOIL LINERS A Thesis by ROBERT CARY SPEAKE, JR. Approved...

Speake, Robert Cary

1986-01-01

166

Soil property database: Southern Great Plains 1997 Hydrology Experiment  

E-print Network

head, and unsaturated hydraulic conductivity) and the soil thermal properties (heat capacity, heat. To better understand the complex and interdependent geophysical processes in the near surface, we conducted surface and the subsurface and the highly nonlinear nature of local-scale water and heat transport

Mohanty, Binayak P.

167

COVER CROP SYSTEM EFFECTS ON CARBON/NITROGEN SEQUESTRATION AND THE PHYSICAL PROPERTIES OF COASTAL PLAIN SOILS UNDER CONSERVATION TILLAGE  

Technology Transfer Automated Retrieval System (TEKTRAN)

Crop growth and water/solute movement are affected by soil properties. Crop growth is affected by soil moisture retention, which relates to soil structure (particle and pore size distribution), which is greatly affected by soil C levels. Soil hydraulic conductivity depends on particle size distrib...

168

Hydraulic conductivity study of compacted clay soils used as landfill liners for an acidic waste  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer Examined the hydraulic conductivity evolution as function of dry density of Tunisian clay soil. Black-Right-Pointing-Pointer Follow the hydraulic conductivity evolution at long-term of three clay materials using the waste solution (pH=2.7). Black-Right-Pointing-Pointer Determined how compaction affects the hydraulic conductivity of clay soils. Black-Right-Pointing-Pointer Analyzed the concentration of F and P and examined the retention of each soil. - Abstract: Three natural clayey soils from Tunisia were studied to assess their suitability for use as a liner for an acid waste disposal site. An investigation of the effect of the mineral composition and mechanical compaction on the hydraulic conductivity and fluoride and phosphate removal of three different soils is presented. The hydraulic conductivity of these three natural soils are 8.5 Multiplication-Sign 10{sup -10}, 2.08 Multiplication-Sign 10{sup -9} and 6.8 Multiplication-Sign 10{sup -10} m/s for soil-1, soil-2 and soil-3, respectively. Soil specimens were compacted under various compaction strains in order to obtain three wet densities (1850, 1950 and 2050 kg/m{sup 3}). In this condition, the hydraulic conductivity (k) was reduced with increasing density of sample for all soils. The test results of hydraulic conductivity at long-term (>200 days) using acidic waste solution (pH = 2.7, charged with fluoride and phosphate ions) shows a decrease in k with time only for natural soil-1 and soil-2. However, the specimens of soil-2 compressed to the two highest densities (1950 and 2050 kg/m{sup 3}) are cracked after 60 and 20 days, respectively, of hydraulic conductivity testing. This damage is the result of a continued increase in the internal stress due to the swelling and to the effect of aggressive wastewater. The analysis of anions shows that the retention of fluoride is higher compared to phosphate and soil-1 has the highest sorption capacity.

Hamdi, Noureddine, E-mail: nouryhamdi@gmail.com [Centre National des Recherches en Science des Materiaux, Borj Cedria Techno-Park, B.P. 95-2050, Hammam Lif, Tunis (Tunisia); Srasra, Ezzeddine [Centre National des Recherches en Science des Materiaux, Borj Cedria Techno-Park, B.P. 95-2050, Hammam Lif, Tunis (Tunisia)

2013-01-15

169

Hydraulics.  

ERIC Educational Resources Information Center

Designed for use in courses where students are expected to become proficient in the area of hydraulics, including diesel engine mechanic programs, this curriculum guide is comprised of fourteen units of instruction. Unit titles include (1) Introduction, (2) Fundamentals of Hydraulics, (3) Reservoirs, (4) Lines, Fittings, and Couplers, (5) Seals,…

Decker, Robert L.

170

HYDRAULIC AND PHYSICAL PROPERTIES OF SALTSTONE GROUTS AND VAULT CONCRETES  

SciTech Connect

The Saltstone Disposal Facility (SDF), located in the Z-Area of the Savannah River Site (SRS), is used for the disposal of low-level radioactive salt solution. The SDF currently contains two vaults: Vault 1 (6 cells) and Vault 4 (12 cells). Additional disposal cells are currently in the design phase. The individual cells of the saltstone facility are filled with saltstone. Saltstone is produced by mixing the low-level radioactive salt solution, with blast furnace slag, fly ash, and cement (dry premix) to form a dense, micro-porous, monolithic, low-level radioactive waste form. The saltstone is pumped into the disposal cells where it subsequently solidifies. Significant effort has been undertaken to accurately model the movement of water and contaminants through the facility. Key to this effort is an accurate understanding of the hydraulic and physical properties of the solidified saltstone. To date, limited testing has been conducted to characterize the saltstone. The primary focus of this task was to estimate the hydraulic and physical properties of three types of saltstone and two vault concretes. The saltstone formulations included saltstone premix batched with (1) Deliquification, Dissolution, and Adjustment (DDA) salt simulant (w/pm 0.60), (2) Actinide Removal Process (ARP)/Modular Caustic Side Solvent Extraction Unit (MCU) salt simulant (w/pm 0.60), and (3) Salt Waste Processing Facility (SWPF) salt simulant (w/pm 0.60). The vault concrete formulations tested included the Vault 1/4 concrete and two variations of the Vault 2 concrete (Mix 1 and Mix 2). Wet properties measured for the saltstone formulations included yield stress, plastic viscosity, wet unit weight, bleed water volume, gel time, set time, and heat of hydration. Hydraulic and physical properties measured on the cured saltstone and concrete samples included saturated hydraulic conductivity, moisture retention, compressive strength, porosity, particle density, and dry bulk density. These properties were determined following a minimum 28 day curing period. Additional testing of the three saltstone formulations was conducted following a minimum 90 day curing period. The compressive strength of each saltstone and concrete material was measured at approximately 14, 28, 56, and 90 days. Recommended hydraulic property values for each saltstone grout and the vault concretes are provided. The hydraulic properties provided for each material include the saturated hydraulic conductivity, dry bulk density, particle density, and porosity. In addition, water retention data are presented for each material along with the van Genuchten transport parameters as determined using the RETC code.

Dixon, K; John Harbour, J; Mark Phifer, M

2008-11-25

171

Soil Properties That Distinguish Ecological Sites  

E-print Network

that determines soil water amounts. Soil properties are features of a soil: · e.g. soil texture, depth #12Soil Properties That Distinguish Ecological Sites Mike Duniway USGS-Southwest Biological Science Properties · Within a climatic zone (e.g. MLRA), differentiation of ecological sites based on soil

172

Long-term hydraulic properties of subsurface flow constructed wetlands  

E-print Network

in subsurface flow constructed wetlands were determined. The media types evaluated were coarse sand, "3/8 inch" pea gravel, "1 inch" river rock, graded "3-5 inch" river rock, and "2 inch" shredded tires (nominal sizes). These hydraulic properties were... conductivity greater than 85% during the six month sampling period, Final hydraulic conductivities ranged from 530 m/day for the pea gravel to 12, 000 in/day for the shredded tires. Final porosities ranged from 0. 19 for the pea gravel to 0. 51...

Turner, Glenn Allen

1994-01-01

173

Plasticity of rhizosphere hydraulic properties as a key for efficient utilization of scarce resources  

PubMed Central

Background It is known that the soil near roots, the so-called rhizosphere, has physical and chemical properties different from those of the bulk soil. Rhizosphere properties are the result of several processes: root and soil shrinking/swelling during drying/wetting cycles, soil compaction by root growth, mucilage exuded by root caps, interaction of mucilage with soil particles, mucilage shrinking/swelling and mucilage biodegradation. These processes may lead to variable rhizosphere properties, i.e. the presence of air-filled gaps between soil and roots; water repellence in the rhizosphere caused by drying of mucilage around the soil particles; or water accumulation in the rhizosphere due to the high water-holding capacity of mucilage. The resulting properties are not constant in time but they change as a function of soil condition, root growth rate and mucilage age. Scope We consider such a variability as an expression of rhizosphere plasticity, which may be a strategy for plants to control which part of the root system will have a facilitated access to water and which roots will be disconnected from the soil, for instance by air-filled gaps or by rhizosphere hydrophobicity. To describe such a dualism, we suggest classifying rhizosphere into two categories: class A refers to a rhizosphere covered with hydrated mucilage that optimally connects roots to soil and facilitates water uptake from dry soils. Class B refers to the case of air-filled gaps and/or hydrophobic rhizosphere, which isolate roots from the soil and may limit water uptake from the soil as well water loss to the soil. The main function of roots covered by class B will be long-distance transport of water. Outlook This concept has implications for soil and plant water relations at the plant scale. Root water uptake in dry conditions is expected to shift to regions covered with rhizosphere class A. On the other hand, hydraulic lift may be limited in regions covered with rhizosphere class B. New experimental methods need to be developed and applied to different plant species and soil types, in order to understand whether such dualism in rhizosphere properties is an important mechanism for efficient utilization of scarce resources and drought tolerance. PMID:23235697

Carminati, Andrea; Vetterlein, Doris

2013-01-01

174

Characterizing Hydraulic Properties and Ground-Water Chemistry in Fractured-Rock Aquifers: A User's Manual  

E-print Network

Characterizing Hydraulic Properties and Ground-Water Chemistry in Fractured-Rock Aquifers: A User., 2007, Characterizing hydraulic properties and ground-water chemistry in fractured-rock aquifers: A user

175

Use of porosity to estimate hydraulic properties of volcanic tuffs  

USGS Publications Warehouse

Correlations of hydraulic properties with easily measured physical properties are useful for purposes of site characterization in heterogeneous sites. Approximately 600 samples of volcanic rocks from Yucca Mountain, Nevada, representing lithologies with a large range of hydraulic properties, were analyzed to develop correlations of effective porosity with saturated hydraulic conductivity and moisture-retention curve-fit parameters that relate to lithologies of varying depositional history and alteration processes. Effective porosity, ??e, defined as the porosity calculated using drying at a relative humidity of -70 MPa, is used in a generalized Kozeny-Carman equation to predict saturated hydraulic conductivity, Ks = b??en, where b and n are constants. The entire dataset has an R2 of 0.36. When samples are grouped according to general lithology, correlations result in an R2 of 0.71 for the crystallized/vitric samples, 0.24 for samples with mineral alteration, and 0.34 for samples with microfractures, thus increasing the predictive capability over that of the total dataset. Published by Elsevier Science Ltd.

Flint, L.E.; Selker, J.S.

2003-01-01

176

Comparative reliability evaluation of lateritic soils as hydraulic barriers  

Microsoft Academic Search

A numerical investigation to determine the existence or otherwise of congruence between laboratory-based and field-based models for predicting hydraulic conductivity of compacted clay liners has been conducted. The comparisons here are based on values of the reliability index estimated with the use of the two models for cases when hydraulic conductivity is assumed to be normally and lognormally distributed. The

J. O. Afolayan; C. M. O. Nwaiwu; K. J. Osinubi

2005-01-01

177

F. Froux et al.Hydraulic properties of Mediterranean conifers Original article  

E-print Network

F. Froux et al.Hydraulic properties of Mediterranean conifers Original article Xylem hydraulic (Received 5 November 2001; accepted 11 February 2002) Abstract ­ We studied the xylem hydraulic traits specific hydraulic conductivity was much higher in Cupressus sempervirens and P. nigra than in Cedrus

Paris-Sud XI, Université de

178

HYDRAULIC REDISTRIBUTION OF SOIL WATER BY ROOTS IN FORESTS OF THE PACIFIC NORTHWEST  

EPA Science Inventory

One aspect of structural complexity of forest canopies is the root system structure belowground, which influences patterns of soil water utilization by trees. Deeply rooted trees and other plants can hydraulically lift water via their roots from several m below the soil surface ...

179

Indirect estimation of near-saturated hydraulic conductivity from readily available soil information  

E-print Network

information N.J. Jarvis a,*, L. Zavattaro b , K. Rajkai c , W.D. Reynolds d , P.-A. Olsen e , M. McGechan f of near-saturated hydraulic conductivity made with tension infiltrometers in 70 soil horizons at 37 at regional scales, is often hampered by a lack of information concerning model input parameters such as soil

Mohanty, Binayak P.

180

Change in the hydraulic properties of a Brazilian clay Ferralsol on clearing for pasture  

E-print Network

Change in the hydraulic properties of a Brazilian clay Ferralsol on clearing for pasture L. C 80 to 300 m in size. The aim of this study was to analyze how the hydraulic properties of a clay retention properties were determined by using pressure cell equipment. We determined the saturated hydraulic

Boyer, Edmond

181

Determining soil hydraulic functions from evaporation experiments by a parameter estimation Approach: Experimental verifications and numerical studies  

NASA Astrophysics Data System (ADS)

A parameter estimation method is developed for the determination of unsaturated soil hydraulic properties from evaporation experiments under laboratory conditions. Variables used in the inversion procedure are soil water pressure heads at various positions and total soil weights, both measured as a function of time during the experiment. Unknown parameters of different analytical expressions used to describe the soil hydraulic properties are estimated by coupling a finite difference solution of the Richards equation with a nonlinear optimization problem. This problem is formulated by minimizing the deviations between the numerical solution of the transient flow process and the real system response measured during the experiment. Minimization of the objective function is performed using a version of the Levenberg-Marquardt's method; the procedure also provides information about the uncertainty in parameter estimates. The performance of the selected parametric relationships is evaluated, and the applicability and accuracy of the proposed inverse method are shown by comparing estimated water retention and hydraulic conductivity functions with experimental results obtained via the instantaneous profile method. Parameter sensitivity analyses and stability of the inverse solutions are discussed with reference to the originally designed evaporation experiment and to an evaporation method that is developed with a view to reducing experimental efforts. Further insights into the properties of existence and uniqueness of inverse solutions are gained by examining contour plots of the objective functions under varying experimental conditions. The results confirm the reliability and flexibility of the proposed method and suggest that the evaporation flux imposed at the upper soil surface may determine the well posedness of the optimization problem.

Romano, Nunzio; Santini, Alessandro

1999-11-01

182

Impacts of an integrated crop-livestock system on soil properties to enhance precipitation capture  

Technology Transfer Automated Retrieval System (TEKTRAN)

Cropping/Livestock systems alter soil properties that are important in enhancing capture of precipitation by developing and maintaining water infiltration and storage. In this paper we will relate soil hydraulic conductivity and other physical properties on managed Old World Bluestem grassland, whea...

183

Evaluation of pedo-transfer functions for unsaturated soil hydraulic conductivity using an independent data set  

Microsoft Academic Search

The paper reviews eight well-known and accepted pedo-transfer functions used for evaluation of soil hydraulic conductivity (saturated and unsaturated) from routinely available soil data. A comprehensive data set containing detailed measurements of 63 German soil horizons, to which none of the models had been previously calibrated, were used for the evaluation of pedo-transfer functions. The paper considers only pedo-transfer functions

B. Wagner; V. R. Tarnawski; V. Hennings; U. Müller; G. Wessolek; R. Plagge

2001-01-01

184

Can pore-scale methods overcome limitations of traditional hydraulic property measurement techniques?  

NASA Astrophysics Data System (ADS)

Conventional methods of determining transport properties on core samples using information from hydraulic conductivity, water retention curves, electrical properties, or formation factor have substantial shortcomings: (1) they represent quasi-1D flow; (2) possess no a priori information on sample's representativity in terms of its internal heterogeneity; (3) measurements may seriously alter sample properties, e.g. sample saturation and through-flow can mobilize fine material potentially causing pore blockage; also, saturation in the laboratory may cause swelling or mineral dissolution of some materials hence affecting the measured hydraulic properties, while full saturation may never occur under field conditions; (4) they require standard shape and size for coring material, thus representing serious limitations for fragile, consolidated, or cemented samples; (5) often represent quasi-static processes, while flow under field conditions is highly dynamic; (6) some fitting parameters are invoked to represent pore-connectivity or "tortuosity" and used in cross-property relationships without real physical meaning (e.g., linkage between water retention curve and unsaturated hydraulic conductivity. Based on experimental data from a broad range of porous materials we show how these shortcomings can be overcame via pore-scale modeling using structural and surface property information. In particular we use following datasets: 1) deep vadose zones for arid environment (central Australia), 2) shallow-to-deep aquifers (Central Russian Upland), 3) agricultural soils known for their preferential flow (Central Russian Upland), and 4) extremely stony forest soils (Russian Far East). Several approaches exist for acquisition of structural information, with the most information-rich being X-ray microtomography. Alternatively, 2D thin-sections may be used with higher spatial resolution but with limited information on connectivity; reconstruction methods (sequential and stochastic) can help resolve the latter limitation. Finally, we illustrate how our pore-scale methods fit in a broader upscaling approach and improve large-scale modeling; current limitations and future challenges are also discussed.

Gerke, Kirill; Vasilyev, Roman; Korost, Dmitry; Karsanina, Marina; Mallants, Dirk; Gorbunova, Ella; Shein, Evgeny; Gartsman, Boris; Bedrikovetsky, Pavel; Tairova, Aliya; Skvortsova, Elena

2013-04-01

185

A topography-based scaling algorithm for soil hydraulic parameters at hillslope scales: Field testing  

NASA Astrophysics Data System (ADS)

Soil hydraulic parameters were upscaled from a 30 m resolution to a 1 km resolution using a new aggregation scheme (described in the companion paper) where the scale parameter was based on the topography. When soil hydraulic parameter aggregation or upscaling schemes ignore the effect of topography, their application becomes limited at hillslope scales and beyond, where topography plays a dominant role in soil deposition and formation. Hence the new upscaling algorithm was tested at the hillslope scale (1 km) across two locations: (1) the Little Washita watershed in Oklahoma, and (2) the Walnut Creek watershed in Iowa. The watersheds were divided into pixels of 1 km resolution and the effective soil hydraulic parameters obtained for each pixel. Each pixel/domain was then simulated using the physically based HYDRUS-3-D modeling platform. In order to account for the surface (runoff/on) and subsurface fluxes between pixels, an algorithm to route infiltration-excess runoff onto downstream pixels at daily time steps and to update the soil moisture states of the downstream pixels was applied. Simulated soil moisture states were compared across scales, and the coarse scale values compared against the airborne soil moisture data products obtained during the hydrology experiment field campaign periods (SGP97 and SMEX02) for selected pixels with different topographic complexities, soil distributions, and land cover. Results from these comparisons show good correlations between simulated and observed soil moisture states across time, topographic variations, location, elevation, and land cover. Stream discharge comparisons made at two gauging stations in the Little Washita watershed also provide reasonably good results as to the suitability of the upscaling algorithm used. Based only on the topography of the domain, the new upscaling algorithm was able to provide coarse resolution values for soil hydraulic parameters which effectively captured the variations in soil moisture across the watershed domains.

Jana, Raghavendra B.; Mohanty, Binayak P.

2012-02-01

186

Hydraulics  

NSDL National Science Digital Library

These interactive learning objects, created by instructors from Fox Valley Technical College and other colleges in the Wisconsin Technical College program, focus on concepts that cover a broad-based electromechanical program. Here visitors will find learning objects in Hydraulics with over 25 lessons in Actuators, Relief Valves, Basic Concepts, and Directional Control Valves.

187

Improving Estimates of Root-zone Soil Water Content Using Soil Hydrologic Properties and Remotely Sensed Soil Moisture  

NASA Astrophysics Data System (ADS)

Newly defined relationships between remotely sensed soil moisture and soil hydraulic parameters were used to develop fine-scale (100 m) maps of root-zone soil moisture (RZSM) content at the regional scale on a daily time-step. There are several key outcomes from our research: (1) the first multi-layer regional dataset of soil hydraulic parameters developed from gSSURGO data for hydrologic modeling efforts in the Chequemegon Ecosystem Atmospheric Study (ChEAS) region, (2) the operation and calibration of a new model for estimating soil moisture flow through the root-zone at eddy covariance towers across the U.S. using remotely sensed active and passive soil moisture products, and (3) region-wide maps of estimated root-zone soil moisture content. The project links soil geophysical analytical approaches (pedotransfer functions) to new applications in remote sensing of soil moisture that detect surface moisture (~5 cm depth). We answer two key questions in soil moisture observation and prediction: (1) How do soil hydrologic properties of U.S. soil types quantitatively relate to surface-to-subsurface water loss? And (2) Does incorporation of fine-scale soil hydrologic parameters with remotely sensed soil moisture data provide improved hindcasts of in situ RZSM content? The project meets several critical research needs in estimation of soil moisture from remote sensing. First, soil moisture is known to vary spatially with soil texture and soil hydraulic properties that do not align well with the spatial resolution of current remote sensing products of soil moisture (~ 50 km2). To address this, we leveraged new advances in gridded soil parameter information (gSSURGO) together with existing remotely sensed estimates of surface soil moisture into a newly emerging semi-empirical modeling approach called SMAR (Soil Moisture Analytical Relationship). The SMAR model was calibrated and cross-validated using existing soil moisture data from a portion of AMERIFLUX tower sites and the NRCS Soil Climate Analysis Network (SCAN). Our preliminary results show good performance of the SMAR model for predicting RZSM at the site level (root mean square error = 0.04). Second, a calibrated SMAR parameter governing the surface to subsurface rate of water flow was related to soil hydraulic properties at the AMERIFLUX tower sites, and region-wide maps of SMAR parameters were developed for the ChEAS region using gSSURGO information. Finally, region-wide maps of RZSM were developed and validated for the ChEAS region. The RZSM products can be directly incorporated with regional CO2 flux modeling, and the results inform - but are not dependent on - efforts that integrate observed soil moisture data with planned NASA missions (e.g., SMAP).

Baldwin, D. C.; Miller, D. A.; Singha, K.; Davis, K. J.; Smithwick, E. A.

2013-12-01

188

Hydraulic properties of a model dike from coupled Bayesian and multi-criteria hydrogeophysical inversion  

NASA Astrophysics Data System (ADS)

SummaryCoupled hydrogeophysical inversion aims to improve the use of geophysical data for hydrological model parameterization. Several numerical studies have illustrated the feasibility and advantages of a coupled approach. However, there is still a lack of studies that apply the coupled inversion approach to actual field data. In this paper, we test the feasibility of coupled hydrogeophysical inversion for determining the hydraulic properties of a model dike using measurements of electrical resistance tomography (ERT). Our analysis uses a two-dimensional (2D) finite element hydrological model (HYDRUS-2D) coupled to a 2.5D finite element electrical resistivity code (CRMOD), and includes explicit recognition of parameter uncertainty by using a Bayesian and multiple criteria framework with the DREAM and AMALGAM population based search algorithms. To benchmark our inversion results, soil hydraulic properties determined from ERT data are compared with those separately obtained from detailed in situ soil water content measurements using Time Domain Reflectometry (TDR). Our most important results are as follows. (1) TDR and ERT data theoretically contain sufficient information to resolve most of the soil hydraulic properties, (2) the DREAM-derived posterior distributions of the hydraulic parameters are quite similar when estimated separately using TDR and ERT measurements for model calibration, (3) among all parameters, the saturated hydraulic conductivity of the dike material is best constrained, (4) the saturation exponent of the petrophysical model is well defined, and matches independently measured values, (5) measured ERT data sufficiently constrain model predictions of water table dynamics within the model dike. This finding demonstrates an innate ability of ERT data to provide accurate hydrogeophysical parameterizations for flooding events, which is of particular relevance to dike management, and (6) the AMALGAM-derived Pareto front demonstrates trade-off in the fitting of ERT and TDR measurements. Altogether, we conclude that coupled hydrogeophysical inversion using a Bayesian approach is especially powerful for hydrological model calibration. The posterior probability density functions of the model parameters and model output predictions contain important information to determine if geophysical measurements provide constraints on hydrological predictions.

Huisman, J. A.; Rings, J.; Vrugt, J. A.; Sorg, J.; Vereecken, H.

2010-01-01

189

Hydrology and Hydraulic Properties of a Bedded Evaporite Formation  

SciTech Connect

The Permian Salado Formation in the Delaware Basin of New Mexico is an extensively studied evaporite deposit because it is the host formation for the Waste Isolation Pilot Plant, a repository for transuranic wastes. Geologic and hydrologic studies of the Salado conducted since the mid-1970's have led to the development of a conceptual model of the hydrogeology of the formation that involves far-field permeability in anhydrite layers and at least some impure halite layers. Pure halite layers and some impure halite layers may not possess an interconnected pore network adequate to provide permeability. Pore pressures are probably very close to lithostatic pressure. In the near field around an excavation, dilation, creep, and shear have created and/or enhanced permeability and decreased pore pressure. Whether flow occurs in the far field under natural gradients or only after some threshold gradient is reached is unknown. If far-field flow does occur, mean pore velocities are probably on the order of a meter per hundreds of thousands to tens of millions of years. Flow dimensions inferred from most hydraulic-test responses are subradial, which is believed to reflect channeling of flow through fracture networks, or portions of fractures, that occupy a diminishing proportion of the radially available space, or through percolation networks that are not ''saturated'' (fully interconnected). This is probably related to the directional nature of the permeability created or enhanced by excavation effects. Inferred values of permeability cannot be separated from their associated flow dimensions. Therefore, numerical models of flow and transport should include heterogeneity that is structured to provide the same flow dimensions as are observed in hydraulic tests. Modeling of the Salado Formation around the WIPP repository should also include coupling between hydraulic properties and the evolving stress field because hydraulic properties change as the stress field changes.

BEAUHEIM,RICHARD L.; ROBERTS,RANDALL M.

2000-11-27

190

Use of field and laboratory methods for estimating unsaturated hydraulic properties under different land-use  

NASA Astrophysics Data System (ADS)

Adequate water management is required to improve the efficiency and sustainability of agricultural systems when water is scarce or over-abundant, especially in the case of land-use changes. In order to quantify, to predict and eventually to control water and solute transport into soil, soil hydraulic properties need to be determined precisely. As their determination is often tedious, expensive and time-consuming, many alternative field and laboratory techniques are now available. The aim of this study was to determine unsaturated soil hydraulic properties under different land-uses and to compare the results obtained with different measurement methods (Beerkan, Disk infiltrometer, Evaporation, pedotransfer function). The study has been realised on a tropical sandy soil in a mini watershed in NE Thailand. The experimental plots were positioned in a rubber tree plantation in different positions along a slope, in ruzi grass pasture and in an original forest site. Non parametric statistics demonstrated that van Genuchten unsaturated soil parameters (Ks, ? and n), were significantly different according to the measurement methods employed whereas location was not a significant discriminating factor when all methods were considered together. However within each method, parameters n and ? were statistically different according to the sites. These parameters were used with Hydrus1D for a one year simulation and computed pressure head did not show noticeable differences for the various sets of parameters, highlighting the fact that for modelling, any of these measurement method could be employed. The choice of the measurement method would therefore be motivated by the simplicity, robustness and its low cost.

Siltecho, S.; Hammecker, C.; Sriboonlue, V.; Clermont-Dauphin, C.; Trelo-ges, V.; Antonino, A. C. D.; Angulo-Jaramillo, R.

2014-06-01

191

Status Report for Remediation Decision Support Project, Task 1, Activity 1.B – Physical and Hydraulic Properties Database and Interpretation  

SciTech Connect

The objective of Activity 1.B of the Remediation Decision Support (RDS) Project is to compile all available physical and hydraulic property data for sediments from the Hanford Site, to port these data into the Hanford Environmental Information System (HEIS), and to make the data web-accessible to anyone on the Hanford Local Area Network via the so-called Virtual Library. In past years efforts were made by RDS project staff to compile all available physical and hydraulic property data for Hanford sediments and to transfer these data into SoilVision{reg_sign}, a commercial geotechnical software package designed for storing, analyzing, and manipulating soils data. Although SoilVision{reg_sign} has proven to be useful, its access and use restrictions have been recognized as a limitation to the effective use of the physical and hydraulic property databases by the broader group of potential users involved in Hanford waste site issues. In order to make these data more widely available and useable, a decision was made to port them to HEIS and to make them web-accessible via a Virtual Library module. In FY08 the objectives of Activity 1.B of the RDS Project were to: (1) ensure traceability and defensibility of all physical and hydraulic property data currently residing in the SoilVision{reg_sign} database maintained by PNNL, (2) transfer the physical and hydraulic property data from the Microsoft Access database files used by SoilVision{reg_sign} into HEIS, which has most recently been maintained by Fluor-Hanford, Inc., (3) develop a Virtual Library module for accessing these data from HEIS, and (4) write a User's Manual for the Virtual Library module. The development of the Virtual Library module was to be performed by a third party under subcontract to Fluor. The intent of these activities is to make the available physical and hydraulic property data more readily accessible and useable by technical staff and operable unit managers involved in waste site assessments and remedial action decisions for Hanford. This status report describes the history of this development effort and progress to date.

Rockhold, Mark L.

2008-09-26

192

Contrasting effects of soil development on hydrological properties and flow paths  

Microsoft Academic Search

Runoff pathways strongly influence hydrologic and biogeochemical losses and landscape evolution. On an evolving landscape, soil development may alter hydrologic properties and thereby change through time the relative importance of various pathways. Here we report in situ soil water retention, unsaturated and saturated hydraulic conductivity, and flow path characteristics of a 300 year old Andisol and a 4.1 million year

Kathleen A. Lohse; William E. Dietrich

2005-01-01

193

A review of the Rawls et al. (1982) soil hydraulic pedotransfer function  

Technology Transfer Automated Retrieval System (TEKTRAN)

For many applications that involve the use of environmental simulation models, soil water retention and hydraulic conductivity data are not available and therefore need to be estimated. The current version of the APEX model – that is being used in the national scale CEAP project to evaluate on-site ...

194

EFFECTS OF ELECTROOSMOSIS ON SOIL TEMPERATURE AND HYDRAULIC HEAD: I. FIELD OBSERVATIONS  

EPA Science Inventory

A field test to quantify the changes of soil temperature and hydraulic head during electroosmosis was conducted. The anode (3.1 m x 3.4 m) was created by laying pieces of titanium mesh coated with mixed metal oxides on top of a 3 cm thick sand layer at a depth of 0.4 m. The catho...

195

EFFECTS OF ELECTROOSMOSIS ON SOIL TEMPERATURE AND HYDRAULIC HEAD: I. FIELD OBSERVATION  

EPA Science Inventory

A field test to quantify the changes of soil temperature and hydraulic head during electroosmosis has been conducted. The anode (3.1 m x 3.4m) was created by laying pieces of titanium mesh coated with mixed metal oxides on tope of a 3 cm thick sand layer at a depth of 0.4 m. The ...

196

Predicting Saturated Hydraulic Conductivity from Percolation Test Results in Layered Silt Loam Soils  

Technology Transfer Automated Retrieval System (TEKTRAN)

The size of on-site waste disposal systems is usually determined by one or more percolation tests performed on the proposed site. The objectives of this study were to develop an empirical relationship between the saturated hydraulic conductivity (Ks) of layered soils and their percolation times (PT)...

197

1 Estimating aquifer hydraulic properties from the inversion of surface 2 Streaming Potential (SP) anomalies  

E-print Network

1 Estimating aquifer hydraulic properties from the inversion of surface 2 Streaming Potential (SP with the geometry of the water table. It follows that 11 SP measurements can be used to estimate aquifer hydraulic and found that we 14 are able to estimate the hydraulic conductivity and the depth 15 and the thickness

Sailhac, Pascal

198

Enrichment strategies and convergence properties of the XFEM for hydraulic fracture problems  

E-print Network

Enrichment strategies and convergence properties of the XFEM for hydraulic fracture problems Finite Ele- ment Method (XFEM) for modeling hydraulic fractures (HF), two classes of boundary value energy, is not suitable for modeling hydraulic fractures in which the uid and the fracture fronts

Peirce, Anthony

199

Estimability analysis for optimization of hysteretic soil hydraulic parameters using data of a field irrigation experiment  

NASA Astrophysics Data System (ADS)

The estimability analysis has been proposed to improve the quality of parameter optimization. For field data, wetting and drying processes may complicate optimization of soil hydraulic parameters. The objectives of this study were to apply estimability analysis for improving optimization of soil hydraulic parameters and compare models with and without considering hysteresis. Soil water pressure head data of a field irrigation experiment were used. The one-dimensional vertical water movement in variably-saturated soil was described with the Richards equation using the HYDRUS-1D code. Estimability of the unimodal van Genuchten - Mualem hydraulic model parameters as well as of the hysteretic parameter model of Parker and Lenhard was classified according to a sensitivity coefficient matrix. The matrix was obtained by sequentially calculating effects of initial parameter variations on changes in the simulated pressure head values. Optimization was carried out by means of the Levenberg-Marquardt method as implemented in the HYDRUS-1D code. The parameters ?, Ks, ?s, and n in the nonhysteretic model were found sensitive and parameter ?s and n strongly correlated with parameter n in the nonhysteretic model. When assuming hysteresis, the estimability was highest for ?w and decreased with soil depth for Ks and ?d, and increased for ?s and n. The hysteretic model could approximate the pressure heads in the soil by considering parameters from wetting and drying periods separately as initial estimates. The inverse optimization could be carried out more efficiently with most estimable parameters. Despite the weaknesses of the local optimization algorithm and the inflexibility of the unimodal van Genuchten model, the results suggested that estimability analysis could be considered as a guidance to better define the optimization scenarios and then improved the determination of soil hydraulic parameters.

Ngo, Viet V.; Gerke, Horst H.; Badorreck, Annika

2014-05-01

200

Sagebrush carrying out hydraulic lift enhances surface soil nitrogen cycling and nitrogen uptake into inflorescences  

PubMed Central

Plant roots serve as conduits for water flow not only from soil to leaves but also from wetter to drier soil. This hydraulic redistribution through root systems occurs in soils worldwide and can enhance stomatal opening, transpiration, and plant carbon gain. For decades, upward hydraulic lift (HL) of deep water through roots into dry, litter-rich, surface soil also has been hypothesized to enhance nutrient availability to plants by stimulating microbially controlled nutrient cycling. This link has not been demonstrated in the field. Working in sagebrush-steppe, where water and nitrogen limit plant growth and reproduction and where HL occurs naturally during summer drought, we slightly augmented deep soil water availability to 14 HL+ treatment plants throughout the summer growing season. The HL+ sagebrush lifted greater amounts of water than control plants and had slightly less negative predawn and midday leaf water potentials. Soil respiration was also augmented under HL+ plants. At summer’s end, application of a gas-based 15N isotopic labeling technique revealed increased rates of nitrogen cycling in surface soil layers around HL+ plants and increased uptake of nitrogen into HL+ plants’ inflorescences as sagebrush set seed. These treatment effects persisted even though unexpected monsoon rainstorms arrived during assays and increased surface soil moisture around all plants. Simulation models from ecosystem to global scales have just begun to include effects of hydraulic redistribution on water and surface energy fluxes. Results from this field study indicate that plants carrying out HL can also substantially enhance decomposition and nitrogen cycling in surface soils. PMID:24191007

Cardon, Zoe G.; Stark, John M.; Herron, Patrick M.; Rasmussen, Jed A.

2013-01-01

201

Construction of Flexible Subterranean Hydraulic Barriers in Soil and Rock  

SciTech Connect

In the management of radioactive waste sites, there is sometimes a need to divert infiltration water; or contain or divert contaminated groundwater. This paper discusses several experimental techniques based on super permeating molten wax. Many of the methods are suited to form both vertical or horizontal barriers in-situ in the ground. The first method is based on thermally controlled permeation grouting between drilled holes that produces a very thick barrier in soil, rock, or even fractured rock up to 600 meters deep. The second method is a variation on jet grouting for producing a thin low cost barrier in soil. Also discussed is a technique for forming an infiltration barrier within the surface soil over an underground tank farm and a method for encapsulating a buried waste without excavation. These new methods can produce durable subterranean barriers of high integrity. These barriers are made with a special malleable wax that soaks into the soil or rock matrix. The wax is far more impermeable than clay or cement and can flex and stretch in response to soil movements. The wax contains no water and is not prone to damage from soil moisture changes. (authors)

Carter, E.E.; Carter, P.E. [Technologies Co, Sugar Land, Texas (United States); Cooper, D.C. [Ph.D. Idaho National Laboratory, Idaho Falls, ID (United States)

2008-07-01

202

Lunar soil properties and soil mechanics  

NASA Technical Reports Server (NTRS)

The study to identify and define recognizable fabrics in lunar soil in order to determine the history of the lunar regolith in different locations is reported. The fabric of simulated lunar soil, and lunar soil samples are discussed along with the behavior of simulated lunar soil under dynamic and static loading. The planned research is also included.

Mitchell, J. K.; Houston, W. N.; Hovland, H. J.

1972-01-01

203

Hydraulic management of a soil moisture controlled SDI wastewater dispersal system in an Alabama Black Belt soil.  

PubMed

Rural areas represent approximately 95% of the 14000 km(2) Alabama Black Belt, an area of widespread Vertisols dominated by clayey, smectitic, shrink-swell soils. These soils are unsuitable for conventional onsite wastewater treatment systems (OWTS) which are nevertheless widely used in this region. In order to provide an alternative wastewater dosing system, an experimental field moisture controlled subsurface drip irrigation (SDI) system was designed and installed as a field trial. The experimental system that integrates a seasonal cropping system was evaluated for two years on a 500-m(2) Houston clay site in west central Alabama from August 2006 to June 2008. The SDI system was designed to start hydraulic dosing only when field moisture was below field capacity. Hydraulic dosing rates fluctuated as expected with higher dosing rates during warm seasons with near zero or zero dosing rates during cold seasons. Lower hydraulic dosing in winter creates the need for at least a two-month waste storage structure which is an insurmountable challenge for rural homeowners. An estimated 30% of dosed water percolated below 45-cm depth during the first summer which included a 30-year historic drought. This massive volume of percolation was presumably the result of preferential flow stimulated by dry weather clay soil cracking. Although water percolation is necessary for OWTS, this massive water percolation loss indicated that this experimental system is not able to effective control soil moisture within its monitoring zone as designed. Overall findings of this study indicated that soil moisture controlled SDI wastewater dosing is not suitable as a standalone system in these Vertisols. However, the experimental soil moisture control system functioned as designed, demonstrating that soil moisture controlled SDI wastewater dosing may find application as a supplement to other wastewater disposal methods that can function during cold seasons. PMID:21621905

He, Jiajie; Dougherty, Mark; Shaw, Joey; Fulton, John; Arriaga, Francisco

2011-10-01

204

Towards soil property retrieval from space: Proof of concept using in situ observations  

NASA Astrophysics Data System (ADS)

Soil moisture is a key variable that controls the exchange of water and energy fluxes between the land surface and the atmosphere. However, the temporal evolution of soil moisture is neither easy to measure nor monitor at large scales because of its high spatial variability. This is mainly a result of the local variation in soil properties and vegetation cover. Thus, land surface models are normally used to predict the evolution of soil moisture and yet, despite their importance, these models are based on low-resolution soil property information or typical values. Therefore, the availability of more accurate and detailed soil parameter data than are currently available is vital, if regional or global soil moisture predictions are to be made with the accuracy required for environmental applications. The proposed solution is to estimate the soil hydraulic properties via model calibration to remotely sensed soil moisture observation, with in situ observations used as a proxy in this proof of concept study. Consequently, the feasibility is assessed, and the level of accuracy that can be expected determined, for soil hydraulic property estimation of duplex soil profiles in a semi-arid environment using near-surface soil moisture observations under naturally occurring conditions. The retrieved soil hydraulic parameters were then assessed by their reliability to predict the root zone soil moisture using the Joint UK Land Environment Simulator model. When using parameters that were retrieved using soil moisture observations, the root zone soil moisture was predicted to within an accuracy of 0.04 m3/m3, which is an improvement of ?0.025 m3/m3 on predictions that used published values or pedo-transfer functions.

Bandara, Ranmalee; Walker, Jeffrey P.; Rüdiger, Christoph

2014-05-01

205

Temperature dependence of unsaturated hydraulic conductivity of two soils.  

USGS Publications Warehouse

The temperature dependence of the soil water matric potential, surface tension, and diffuse double-layer thickness are discussed in terms of their possible interaction with the unsaturated conductivity values obtained. A case is presented for further study to isolate these temperature-sensitive parameters as well as additional parameters related to fluid flow path changes with temperature.-from Author

Constantz, J.

1982-01-01

206

Integrating models to simulate emergent behaviour: effects of organic matter on soil hydraulics in the ICZ-1D soil-vegetation model  

NASA Astrophysics Data System (ADS)

Soil develops as a result of interacting processes, many of which have been described in more or less detailed models. A key challenge in developing predictive models of soil function is to integrate processes that operate across a wide range of temporal and spatial scales. Many soil functions could be classified as "emergent", since they result from the interaction of subsystems. For example, soil organic matter (SOM) dynamics are commonly considered in relation to carbon storage, but can have profound effects on soil hydraulic properties that are conventionally considered to be static. Carbon fixed by plants enters the soil as litterfall, root turnover or via mycorrhizae. Plants need water and nutrients to grow, and an expanding root system provides access to a larger volume of soil for uptake of water and nutrients. Roots also provide organic exudates, such as oxalate, which increase nutrient availability. Carbon inputs are transformed at various rates into soil biota, CO2, and more persistent forms of organic matter. The SOM is partly taken up into soil aggregates of variable sizes, which slows down degradation. Water availability is an important factor as both plant growth and SOM degradation can be limited by shortage of water. Water flow is the main driver for transport of nutrients and other solutes. The flow of water in turn is influenced by the presence of SOM as this influences soil water retention and hydraulic conductivity. Towards the top of the unsaturated zone, bioturbation by the soil fauna transports both solid material and solutes. Weathering rates of minerals determine the availability of many nutrients and are in turn dependent on parameters such as pH, water content, CO2 pressure and oxalate concentration. Chemical reactions between solutes, dissolution and precipitation, and exchange on adsorption sites further influence solute concentrations. Within the FP7 SoilTrEC project, we developed a model that incorporates all of these processes, to explore the complex interactions involved in soil development and change. We were unable to identify appropriately-detailed existing models for plant productivity and for the dynamics of soil aggregation and porosity, and so developed the PROSUM and CAST models, respectively, to simulate these subsystems. Moreover, we applied the BRNS generator to obtain a chemical equilibrium model. These were combined with HYDRUS-1D (water and solute transport), a weathering model (derived from the SAFE model) and a simple bioturbation model. The model includes several feedbacks, such as the effect of soil organic matter on water retention and hydraulic conductivity. We encountered several important challenges when building the integrated model. First, a mechanism was developed that initiates the execution of a single time step for an individual sub-model and accounts for the relevant mass transfers between sub-models. This allows for different and sometimes variable time step duration in the submodels. Secondly, we removed duplicated processes and identified and included relevant solute production terms that had been neglected. The model is being tested against datasets obtained from several Soil Critical Zone Observatories in Europe. This contribution focuses on the design strategy for the model.

Valstar, Johan; Rowe, Ed; Konstantina, Moirogiorgou; Giannakis, Giorgos; Nikolaidis, Nikolaos

2014-05-01

207

Determination of Soil Hydraulic Parameters Through 1-D Infiltration Fluxes Using a Dimensionless Numerical Model  

NASA Astrophysics Data System (ADS)

Modeling of hydrological water transfers in the unsaturated zone of a watershed requires hydraulic characterization of soils. This characterization is commonly described by the hydraulic conductivity curve and the water retention curve which, for the purposes of flux calculations, are approximated by mathematical functions. With traditional methods, assessment of the involved parameters requires considerable amounts of time and resources when a great number of grid sampling points is needed. We present a simple and accurate method to determine the hydraulic conductivity at saturation (Ks) and the normalisation parameter of the water retention curve (alpha) of the van Genuchten functions for the case of 1-D vertical infiltration under a constant pressure head at the soil surface. The method is based on the optimization of cumulative infiltration versus time data using a numerical dimensionless solution of the Richards' equation. Other data requirements are: shape parameters of the retention curve, obtained from textural information, and initial and saturated water contents of the soil. The method is tested for experimental data contrasting two soils: a well graded silt and a structured coarse sand, both having uniform initial water contents and a null pressure heads at the surface. The results show that the parameters Ks and alpha can be accurately predicted but further research is necessary to test different initial and pressure head conditions.

Soria Ugalde, J. M.

2006-12-01

208

Importance of internal hydraulic redistribution for prolonging the lifespan of roots in dry soil.  

PubMed

Redistribution of water within plants could mitigate drought stress of roots in zones of low soil moisture. Plant internal redistribution of water from regions of high soil moisture to roots in dry soil occurs during periods of low evaporative demand. Using minirhizotrons, we observed similar lifespans of roots in wet and dry soil for the grapevine 'Merlot' (Vitis vinifera) on the rootstock 101-14 Millardet de Gramanet (Vitis riparia x Vitis rupestris) in a Napa County, California vineyard. We hypothesized that hydraulic redistribution would prevent an appreciable reduction in root water potential and would contribute to prolonged root survivorship in dry soil zones. In a greenhouse study that tested this hypothesis, grapevine root systems were divided using split pots and were grown for 6 months. With thermocouple psychrometers, we measured water potentials of roots of the same plant in both wet and dry soil under three treatments: control (C), 24 h light + supplemental water (LW) and 24 h light only (L). Similar to the field results, roots in the dry side of split pots had similar survivorship as roots in the wet side of the split pots (P = 0.136) in the C treatment. In contrast, reduced root survivorship was directly associated with plants in which hydraulic redistribution was experimentally reduced by 24 h light. Dry-side roots of plants in the LW treatment lived half as long as the roots in the wet soil despite being provided with supplemental water (P < 0.0004). Additionally, pre-dawn water potentials of roots in dry soil under 24 h of illumination (L and LW) exhibited values nearly twice as negative as those of C plants (P = 0.034). Estimates of root membrane integrity using electrolyte leakage were consistent with patterns of root survivorship. Plants in which nocturnal hydraulic redistribution was reduced exhibited more than twice the amount of electrolyte leakage in dry roots compared to those in wet soil of the same plant. Our study demonstrates that besides a number of ecological advantages to protecting tissues against desiccation, internal hydraulic redistribution of water is a mechanism consistent with extended root survivorship in dry soils. PMID:18028280

Bauerle, T L; Richards, J H; Smart, D R; Eissenstat, D M

2008-02-01

209

Influence of irrigation and fertilization on transpiration and hydraulic properties of Populus deltoides.  

SciTech Connect

Summary Long-term hydraulic acclimation to resource availability was explored in 3-year-bld Populus deltoides Bartr. ex Marsh. clones by examining transpiration. leaf-specific hydraulic conductance (GL), canopy stomatal conductance (Gs) and leaf to sapwood area ratio (AL:Asi)n response to imgation (13 and 551 mm year in addition to ambient precipitation) and fertilization (0 and 120 kg N ha-' year-'). Sap flow was measured continuously over one growing season with thermal dissipation probes. Fertilization had a greater effect on growth and hydraulic properties than imgation, and fertilization effects were independent of irrigation treatment. Transpiration on a ground area basis (E) ranged between 0.3 and 1.8 mm day-', and increased 66% and 90% in response to imgation and fertilization, respectively. Increases in GL, Gs at a reference vapor pressure deficit of 1 kPa, and transpiration per unit leaf areain response to increases in resource availability were associated with reductions in AL:As and consequently a minimal change in the water potential gradient from soil to leaf. Imgation and fertilization increased leaf area index similarly, from an average 1.16 in control stands to 1.45, but sapwood area was increased from 4.0 to 6.3 m ha-' by irrigation and from 3.7 to 6.7 m2 ha-' by fertilization. The balance between leaf area and sapwood area was important in understanding long-term hydraulic acclimation to resource availability and mechanisms controlling maximum productivity in Populus deltoides.

Samuelson, Lisa, J.; Stokes, Thomas, A.; Coleman, Mark, D.

2007-02-01

210

Influence of irrigation and fertilization on transpiration and hydraulic properties of Populus deltoides.  

PubMed

Long-term hydraulic acclimation to resource availability was explored in 3-year-old Populus deltoides Bartr. ex Marsh. clones by examining transpiration, leaf-specific hydraulic conductance (G(L)), canopy stomatal conductance (G(S)) and leaf to sapwood area ratio (A(L):A(S)) in response to irrigation (13 and 551 mm year(-1) in addition to ambient precipitation) and fertilization (0 and 120 kg N ha(-1) year(-1)). Sap flow was measured continuously over one growing season with thermal dissipation probes. Fertilization had a greater effect on growth and hydraulic properties than irrigation, and fertilization effects were independent of irrigation treatment. Transpiration on a ground area basis (E) ranged between 0.3 and 1.8 mm day(-1), and increased 66% and 90% in response to irrigation and fertilization, respectively. Increases in G(L), G(S) at a reference vapor pressure deficit of 1 kPa, and transpiration per unit leaf area in response to increases in resource availability were associated with reductions in A(L):A(S) and consequently a minimal change in the water potential gradient from soil to leaf. Irrigation and fertilization increased leaf area index similarly, from an average 1.16 in control stands to 1.45, but sapwood area was increased from 4.0 to 6.3 m(2) ha(-1) by irrigation and from 3.7 to 6.7 m(2) ha(-1) by fertilization. The balance between leaf area and sapwood area was important in understanding long-term hydraulic acclimation to resource availability and mechanisms controlling maximum productivity in Populus deltoides. PMID:17267367

Samuelson, Lisa J; Stokes, Thomas A; Coleman, Mark D

2007-05-01

211

Comparison of soil extraction techniques for organophosphorous hydraulic fluids  

SciTech Connect

The efficiencies of three soil extraction techniques for removal of non-pesticidal organophosphates were compared. Traditional soxhlet extraction is compared to supercritical fluid extraction (SFE) and a high-pressure, elevated temperature, low solvent volume technique referred to here as HPSE (high-pressure solvent extraction). SFE methods were optimized by varying parameters of temperature, pressure and methanol polarity modifier. SFE recoveries under optimum conditions were at least 90% as efficient as Soxhlet in the extraction of OPs from both spiked and native soils. HPSE experiments showed efficiency and consistency of recovery over a range of temperatures up to 200{degrees} and pressures up to 2000psi, with average recoveries superior to those of Soxhlet extraction. HPSE and SFE provide extraction efficiencies comparable to Soxhlet with substantial savings of time and cost.

David, M.D.; Seiber, J.N. [Univ. of Nevada, Reno, NV (United States)

1996-10-01

212

Soil fauna, soil properties and geo-ecosystem functioning  

NASA Astrophysics Data System (ADS)

The impact of soil fauna on soil processes is of utmost importance, as the activity of soil fauna directly affects soil quality. This is expressed by the direct effects of soil fauna on soil physical and soil chemical properties that not only have great importance to food production and ecosystems services, but also on weathering and hydrological and geomorphological processes. Soil animals can be perceived as ecosystem engineers that directly affect the flow of water, sediments and nutrients through terrestrial ecosystems. The biodiversity of animals living in the soil is huge and shows a huge range in size, functions and effects. Most work has been focused on only a few species such as earthworms and termites, but in general the knowledge on the effect of soil biota on soil ecosystem functioning is limited as it is for their impact on processes in the soil and on the soil surface. In this presentation we would like to review some of the impacts of soil fauna on soil properties that have implications for geo-ecosystem functioning and soil formation processes.

Cammeraat, L. H.

2012-04-01

213

Soil property effects on wind erosion of organic soils  

NASA Astrophysics Data System (ADS)

Histosols (also known as organic soils, mucks, or peats) are soils that are dominated by organic matter (OM > 20%) in half or more of the upper 80 cm. Forty two states have a total of 21 million ha of Histosols in the United States. These soils, when intensively cropped, are subject to wind erosion resulting in loss of crop productivity and degradation of soil, air, and water quality. Estimating wind erosion on Histosols has been determined by USDA-Natural Resources Conservation Service (NRCS) as a critical need for the Wind Erosion Prediction System (WEPS) model. WEPS has been developed to simulate wind erosion on agricultural land in the US, including soils with organic soil material surfaces. However, additional field measurements are needed to understand how soil properties vary among organic soils and to calibrate and validate estimates of wind erosion of organic soils using WEPS. Soil properties and sediment flux were measured in six soils with high organic contents located in Michigan and Florida, USA. Soil properties observed included organic matter content, particle density, dry mechanical stability, dry clod stability, wind erodible material, and geometric mean diameter of the surface aggregate distribution. A field portable wind tunnel was used to generate suspended sediment and dust from agricultural surfaces for soils ranging from 17% to 67% organic matter. The soils were tilled and rolled to provide a consolidated, friable surface. Dust emissions and saltation were measured using an isokinetic vertical slot sampler aspirated by a regulated suction source. Suspended dust was sampled using a Grimm optical particle size analyzer. Particle density of the saltation-sized material (>106 ?m) was inversely related to OM content and varied from 2.41 g cm-3 for the soil with the lowest OM content to 1.61 g cm-3 for the soil with highest OM content. Wind erodible material and the geometric mean diameter of the surface soil were inversely related to dry clod stability. The effect of soil properties on sediment flux varied among flux types. Saltation flux was adequately predicted with simple linear regression models. Dry mechanical stability was the best single soil property linearly related to saltation flux. Simple linear models with soil properties as independent variables were not well correlated with PM10E values (mass flux). A second order polynomial equation with OM as the independent variable was found to be most highly correlated with PM10E values. These results demonstrate that variations in sediment and dust emissions can be linked to soil properties using simple models based on one or more soil properties to estimate saltation mass flux and PM10E values from organic and organic-rich soils.

Zobeck, Ted M.; Baddock, Matthew; Scott Van Pelt, R.; Tatarko, John; Acosta-Martinez, Veronica

2013-09-01

214

Systematic Variability of Soil Hydraulic Conductivity Across Three Vertisol Catenas  

E-print Network

/08 0 20 40 60 80 P re ci pi ta tio n, m m 1/7 /09 1/2 7/0 9 2/1 6/0 9 3/8 /09 3/2 8/0 9 4/1 7/0 9 5/7 /09 5/2 7/0 9 6/1 6/0 9 7/6 /09 7/2 6/0 9 8/1 5/0 9 9/4 /09 9/2 4/0 9 10 /14 /09 11 /3/ 09.... Saturated hydraulic conductivity (Ks) was calculated using the following equation (Reynolds et al., 2002b): G72dGbe6 Gd4c Gbe4GcdeG123eGbc1 G123aGbbcGc2d Gbd7Gb3eGbbcGc2e Gbd4G123bG3a4 G123fGb3eG123cGb35 G123eGc08G5dbG123aGbbcGc2d Gbd7Gb3eGbbcGc2e Gbd4G...

Rivera, Leonardo Daniel

2011-10-21

215

Pharmaceuticals' sorptions relative to properties of thirteen different soils.  

PubMed

Transport of human and veterinary pharmaceuticals in soils and consequent ground-water contamination are influenced by many factors, including compound sorption on soil particles. Here we evaluate the sorption isotherms for 7 pharmaceuticals on 13 soils, described by Freundlich equations, and assess the impact of soil properties on various pharmaceuticals' sorption on soils. Sorption of ionizable pharmaceuticals was, in many cases, highly affected by soil pH. The sorption coefficient of sulfamethoxazole was negatively correlated to soil pH, and thus positively related to hydrolytic acidity and exchangeable acidity. Sorption coefficients for clindamycin and clarithromycin were positively related to soil pH and thus negatively related to hydrolytic acidity and exchangeable acidity, and positively related to base cation saturation. The sorption coefficients for the remaining pharmaceuticals (trimethoprim, metoprolol, atenolol, and carbamazepine) were also positively correlated with the base cation saturation and cation exchange capacity. Positive correlations between sorption coefficients and clay content were found for clindamycin, clarithromycin, atenolol, and metoprolol. Positive correlations between sorption coefficients and organic carbon content were obtained for trimethoprim and carbamazepine. Pedotransfer rules for predicting sorption coefficients of various pharmaceuticals included hydrolytic acidity (sulfamethoxazole), organic carbon content (trimethoprimand carbamazepine), base cation saturation (atenolol and metoprolol), exchangeable acidity and clay content (clindamycin), and soil active pH and clay content (clarithromycin). Pedotransfer rules, predicting the Freundlich sorption coefficients, could be applied for prediction of pharmaceutical mobility in soils with similar soil properties. Predicted sorption coefficients together with pharmaceutical half-lives and other imputes (e.g., soil-hydraulic, geological, hydro-geological, climatic) may be used for assessing potential ground-water contamination. PMID:25569579

Kodešová, Radka; Grabic, Roman; Ko?árek, Martin; Klement, Aleš; Golovko, Oksana; Fér, Miroslav; Nikodem, Antonín; Jakšík, Ond?ej

2015-04-01

216

Nitrate Control of Root Hydraulic Properties in Plants: Translating Local Information to  

E-print Network

Nitrate Control of Root Hydraulic Properties in Plants: Translating Local Information to Whole nutrients such as nitrate. Whereas proliferation of roots might help in the longer term, nitrate in nitrate concentration around roots induces an immediate alteration of root hydraulic properties

Holbrook, N. Michele

217

Comparison of methods for determining soil hydraulic characteristics  

E-print Network

auger hole (L). Db Bulk density (M/L ). 3 Dp Depth of highly permeable material beneath auger hole (L). Dw Fcp HB Soil water diffusivity (L /T). Flow factor, dimensionaless. Centripetal force per unit mass (L/T ). Total head (L). Head..., D is the depth of the slowly permeable material beneath the auger hole (L), Dp is the depth of the highly permeable material below the auger hole (L), and d is the depth of penetration of the inner tube into the bottom of the auger hole (L...

Byrd Humphreys, Kathryn

1979-01-01

218

Vital Soil: Function, Value and Properties.  

Technology Transfer Automated Retrieval System (TEKTRAN)

This article is a review of the book, Vital Soil: Function, Value and Properties. Soil vitality has been defined as the ability of soil ecosystems to stay in balance in a changing world. The soil environment and the life that it supports developed over centuries and millennia, but careless human ac...

219

Laboratory evaluation of the constant rate of strain and constant head techniques for measurement of the hydraulic conductivity of fine grained soils  

E-print Network

This thesis evaluates the constant rate of strain and constant head techniques for measurement of the hydraulic conductivity of fine grained soils. A laboratory program compares hydraulic conductivity measurements made ...

Adams, Amy Lynn

2011-01-01

220

Physical and hydraulic characteristics of bentonite-amended soil from Area 5, Nevada Test Site  

SciTech Connect

Radioactive waste requires significant isolation from the biosphere. Shallow land burial using low-permeability covers are often used to prevent the release of impounded material. This report details the characterization of a soil mixture intended for use as the low-permeability component of a radioactive waste disposal site. The addition of 6.5 percent bentonite to the sandy soils of the site reduced the value of saturated hydraulic conductivity (K{sub s}) by more than two orders of magnitude to 7.6 {times} 10{minus}{sup 8} cm/sec. Characterization of the soil mixture included measurements of grain density, grain size distribution, compaction, porosity, dry bulk density, shear strength, desiccation shrinkage, K{sub s}, vapor conductivity, air permeability, the characteristic water retention function, and unsaturated hydraulic conductivity by both experimental and numerical estimation methods. The ability of the soil layer to limit infiltration in a simulated application was estimated in a one-dimensional model of a landfill cover.

Albright, W. [University and Community Coll. System of Nevada, Reno, NV (United States). Water Resources Center, Desert Research Institute

1995-08-01

221

Determination of soil hydraulic parameters with an inverse model for 1D and 2D infiltration  

NASA Astrophysics Data System (ADS)

Determination of soil hydraulic parameters is important for modelling of hydrological transfer processes in the unsaturated zone of a watershed. However, assessment of these parameters at a great number of grid locations with traditional methods requires considerable time and resources. In this work, a simple method is developed to determine the hydraulic conductivity at saturation (Ks) and the normalisation parameter of the water retention curve (hg which equals 1/alfa for the van Genuchten water retention curve) for the cases of vertical and axisymmetrical infiltration subject to a constant pressure head at the soil surface. While the method is based on the optimisation of a dimensionless solution of the Richards equation, the data requirements are: i) a cumulative infiltration-time curve (e.g., obtained with a disk permeameter); ii) the pressure shape parameters of the soil characteristic curves (e.g., m, n) which can easily be obtained from textural information; and iii) the initial volumetric water content and the surface boundary condition hs < 0. The method is tested for synthetic data generated with the Hydrus-2D code for the Mualem-van Genuchten soil characteristic functions. Obviously, the method can be applied for any other set of functions. The results show that the parameters Ks and hg can be accurately predicted independent of the number of points and the time span of infiltration. However, further research is necessary to test the sensitivity of other variables.

Soria, J. M.; Angulo-Jaramillo, R.; Haverkamp, R.; Leij, F. J.

2003-04-01

222

Trade-offs between xylem hydraulic properties, wood anatomy and yield in Populus.  

PubMed

Trees face the dilemma that achieving high plant productivity is accompanied by a risk of drought-induced hydraulic failure due to a trade-off in the trees' vascular system between hydraulic efficiency and safety. By investigating the xylem anatomy of branches and coarse roots, and measuring branch axial hydraulic conductivity and vulnerability to cavitation in 4-year-old field-grown aspen plants of five demes (Populus tremula L. and Populus tremuloides Michx.) differing in growth rate, we tested the hypotheses that (i) demes differ in wood anatomical and hydraulic properties, (ii) hydraulic efficiency and safety are related to xylem anatomical traits, and (iii) aboveground productivity and hydraulic efficiency are negatively correlated to cavitation resistance. Significant deme differences existed in seven of the nine investigated branch-related anatomical and hydraulic traits but only in one of the four coarse-root-related anatomical traits; this likely is a consequence of high intra-plant variation in root morphology and the occurrence of a few 'high-conductivity roots'. Growth rate was positively related to branch hydraulic efficiency (xylem-specific conductivity) but not to cavitation resistance; this indicates that no marked trade-off exists between cavitation resistance and growth. Both branch hydraulic safety and hydraulic efficiency significantly depended on vessel size and were related to the genetic distance between the demes, while the xylem pressure causing 88% loss of hydraulic conductivity (P88 value) was more closely related to hydraulic efficiency than the commonly used P50 value. Deme-specific variation in the pit membrane structure may explain why vessel size was not directly linked to growth rate. We conclude that branch hydraulic efficiency is an important growth-influencing trait in aspen, while the assumed trade-off between productivity and hydraulic safety is weak. PMID:25009155

Hajek, Peter; Leuschner, Christoph; Hertel, Dietrich; Delzon, Sylvain; Schuldt, Bernhard

2014-07-01

223

Transfer of Physical and Hydraulic Properties Databases to the Hanford Environmental Information System - PNNL Remediation Decision Support Project, Task 1, Activity 6  

SciTech Connect

This report documents the requirements for transferring physical and hydraulic property data compiled by PNNL into the Hanford Environmental Information System (HEIS). The Remediation Decision Support (RDS) Project is managed by Pacific Northwest National Laboratory (PNNL) to support Hanford Site waste management and remedial action decisions by the U.S. Department of Energy and one of their current site contractors - CH2M-Hill Plateau Remediation Company (CHPRC). The objective of Task 1, Activity 6 of the RDS project is to compile all available physical and hydraulic property data for sediments from the Hanford Site, to port these data into the Hanford Environmental Information System (HEIS), and to make the data web-accessible to anyone on the Hanford Local Area Network via the so-called Virtual Library.1 These physical and hydraulic property data are used to estimate parameters for analytical and numerical flow and transport models that are used for site risk assessments and evaluation of remedial action alternatives. In past years efforts were made by RDS project staff to compile all available physical and hydraulic property data for Hanford sediments and to transfer these data into SoilVision{reg_sign}, a commercial geotechnical software package designed for storing, analyzing, and manipulating soils data. Although SoilVision{reg_sign} has proven to be useful, its access and use restrictions have been recognized as a limitation to the effective use of the physical and hydraulic property databases by the broader group of potential users involved in Hanford waste site issues. In order to make these data more widely available and useable, a decision was made to port them to HEIS and to make them web-accessible via a Virtual Library module. In FY08 the original objectives of this activity on the RDS project were to: (1) ensure traceability and defensibility of all physical and hydraulic property data currently residing in the SoilVision{reg_sign} database maintained by PNNL, (2) transfer the physical and hydraulic property data from the Microsoft Access database files used by SoilVision{reg_sign} into HEIS, which is currently being maintained by CHRPC, (3) develop a Virtual Library module for accessing these data from HEIS, and (4) write a User's Manual for the Virtual Library module. The intent of these activities is to make the available physical and hydraulic property data more readily accessible and useable by technical staff and operable unit managers involved in waste site assessments and remedial action decisions for Hanford. In FY08 communications were established between PNNL and staff from Fluor-Hanford Co. (who formerly managed HEIS) to outline the design of a Virtual Library module that could be used to access the physical and hydraulic property data that are to be transferred into HEIS. Data dictionaries used by SoilVision{reg_sign} were also provided to Fluor-Hanford personnel (who are now with CHPRC). During ongoing work to ensure traceability and defensibility of all physical and hydraulic property data that currently reside in the SoilVision{reg_sign} database, it was recognized that further work would be required in this effort before the data were actually ported into HEIS. Therefore work on the Virtual Library module development and an accompanying User's Guide was deferred until an unspecified later date. In FY09 efforts have continued to verify the traceability and defensibility of the physical and hydraulic property datasets that are currently being maintained by PNNL. Although this is a work in progress, several of these datasets should be ready for transfer to HEIS in the very near future. This document outlines a plan for the migration of these datasets into HEIS.

Rockhold, Mark L.; Middleton, Lisa A.

2009-03-31

224

Engineering Properties of NPK Fertilizer Modified Soil  

E-print Network

NPK fertilizer is applied to the soil to modify its properties to give greater crop yield. These soil properties include: unit weight, void ratio, water content, and plasticity, tensile strength, compressibility, permeability and compact ability. Thus it becomes imperative to examine the engineering properties of NPK 20-10-5 fertilizer modified soils. Analysis of test results showed that the liquid limit, shrinkage limit, coefficient of permeability, and void ratio are decreased by the addition of fertilizer. It reduces the shear strength parameters of a soil. Therefore, NPK 20-10-5 fertilizer decreases the bearing capacity of soil and thereby increasing its erodibility

Ezeokonkwo J. C

225

Relationship of catchment topography and soil hydraulic characteristics to lake alkalinity in the northeastern United States  

SciTech Connect

The authors undertook the task of determining whether base flow alkalinity of surface waters in the northeastern United States is related to indices of soil contact time and flow path partitioning that are derived from topographic and soils information. The influence of topography and soils on catchment hydrology has been incorporated previously in the variable source area model TOPMODEL as the relative frequency distribution of ln(a/Kb tan B), where ln is the Naperian logarithm, a is the area drained per unit contour, K is the saturated hydraulic conductivity, b is the soil depth, and tan B is the slope. Using digital elevation and soil survey data, the authors calculated the ln (a/Kb tan B) distribution for 145 catchments. Indices of flow path partitioning and soil contact time were derived from the ln(a/Kb tan B) distributions and compared to measurements of alkalinity in lakes to which the catchments drain. They found that alkalinity was, in general, positively correlated with the index of soil contact time, whereas the correlation between alkalinity and the flow path partitioning index was weak at best. A portion of the correlation between the soil contact time index and alkalinity was attributable to covariation with soil base saturation and cation exchange capacity, while another portion was found to be independent of these factors. Although their results indicate that catchments with long soil contact time indices are most likely to produce high alkalinity base flow, a sensitivity analysis of TOPMODEL suggests that surface waters of these same watersheds may be susceptible to alkalinity depressions during storm events, due to the role of flow paths.

Wolock, D.M.; Hornberger, G.M.; Beven, K.J.; Campbell, W.G.

1989-01-01

226

Influence of hydraulic hysteresis on the mechanical behavior of unsaturated soils and interfaces  

NASA Astrophysics Data System (ADS)

Unsaturated soils are commonly widespread around the world, especially at shallow depths from the surface. The mechanical behavior of this near surface soil is influenced by the seasonal variations such as rainfall or drought, which in turn may have a detrimental effect on many structures (e.g. retaining walls, shallow foundations, mechanically stabilized earth walls, soil slopes, and pavements) in contact with it. Thus, in order to better understand this behavior, it is crucial to study the complex relationship between soil moisture content and matric suction (a stress state variable defined as pore air pressure minus pore water pressure) known as the Soil Water Characteristic Curve (SWCC). In addition, the influence of hydraulic hysteresis on the behavior of unsaturated soils, soil-structure interaction (i.e. rough and smooth steel interfaces, soil-geotextile interfaces) and pavement subgrade (depicted herein mainly by resilient modulus, Mr) was also studied. To this end, suction-controlled direct shear tests were performed on soils, rough and smooth steel interfaces and geotextile interface under drying (D) and wetting after drying (DW). The shearing behavior is examined in terms of the two stress state variables, matric suction and net normal stress. Results along the D and DW paths indicated that peak shear strength increased with suction and net normal stress; while in general, the post peak shear strength was not influenced by suction for rough interfaces and no consistent trend was observed for soils and soil-geotextiles interfaces. Contrary to saturated soils, results during shearing at higher suction values (i.e. 25 kPa and above) showed a decrease in water content eventhough the sample exhibited dilation. A behavior postulated to be related to disruption of menisci and/or non-uniformity of pore size which results in an increase in localized pore water pressures. Interestingly, wetting after drying (DW) test results showed higher peak and post peak shear strength than that of the drying (D) tests. This is believed to be the result of many factors such as: (1) cyclic suction stress loading, (2) water content (less on wetting than drying), and (3) type of soil. The cyclic suction loading may have induced irrecoverable plastic strains, resulting in stiffer samples for wetting tests as compared to drying. Additionally, water may be acting as a lubricant and thus resulting in lower shear strength for test samples D with higher water contents than DW samples. Furthermore, various shear strength models were investigated for their applicability to the experimental data. Models were proposed for the prediction of shear strength with suction based on the SWCC. The models are able to predict the shear strength of unsaturated soil and interfaces due to drying and wetting (i.e. hydraulic hysteresis) by relating directly to the SWCC. The proposed models were used and partly validated by predicting different test results from the literature. In addition, an existing elastoplastic constitutive model was investigated and validated by comparing the predicted and experimental (stress-displacement, volume change behavior) results obtained from rough and geotextile interface tests. This study also explores the effect of hydraulic hysteresis on the resilient modulus (Mr) of subgrade soils. Suction-controlled Mr tests were performed on compacted samples along the primary drying, wetting, secondary drying and wetting paths. Two test types were performed to check the effect of cyclic deviatoric stress loading on the results. First, M r tests were performed on the same sample at each suction (i.e. 25, 50, 75, 100 kPa) value along all the paths (drying, wetting etc.). A relationship between resilient modulus (Mr) and matric suction was obtained and identified as the resilient modulus characteristic curve (MRCC). MRCC results indicated that Mr increased with suction along the drying curve. On the other hand, results on the primary wetting indicated higher Mr than that of the primary drying and the secondary drying. The second type of test

Khoury, Charbel N.

227

Laboratory-Measured and Property-Transfer Modeled Saturated Hydraulic Conductivity of Snake River Plain  

E-print Network

Laboratory-Measured and Property-Transfer Modeled Saturated Hydraulic Conductivity of Snake River Conductivity of Snake River Plain Aquifer Sediments at the Idaho National Laboratory, Idaho By Kim S. Perkins saturated hydraulic conductivity of Snake River Plain aquifer sediments at the Idaho National Laboratory

228

Communicating soil property variability in heterogeneous soil mapping units  

NASA Astrophysics Data System (ADS)

Soil properties and classes can change over very short distances. For the purpose of scale, clarity and field sampling density, soil maps in England and Wales commonly use mapping units which are groupings of taxonomic soil series, commonly found in association with each other in the landscape. These mixed units (Soil Associations), typically contain between 3 and 7 soil series with physical or chemical properties, which can vary across the mapping unit, or may be relatively homogeneous. The degree of variation is not constant between soil properties, for instance, pH may be relatively constant, but volumetric shrinkage potential may be highly variable. Over the past ten years, the number of users of GIS soil property maps has dramatically increased, yet the vast majority of these users do not have a soil or geoscience background. They are instead practitioners in specific industries. As a result, new techniques have been developed to communicate the variation in maps of soil properties to a non-expert audience. GIS data structures allow more flexibility in the reporting of uncertainty or variation in soil mapping units than paper-based maps. Some properties are categorical, others continuous. In England and Wales, the national and regional memberships of soil associations are available, with areal percentages of the comprising soil series being estimated for each association by a combination of expert judgment and field observations. Membership at a local scale can vary considerably from the national average. When summarizing across a whole map unit, for continuous variables, rarely is it appropriate to provide a mean value, or even a weighted average based on membership percentage of the association. Such approaches can make a nonsense of wide-ranging data. For instance a soil association comprising soil series with highly different percentages of sand, silt and clay may result in a 'loamy' mean soil texture which is not reflective of any of the comprising soils. For categorical data, the choice of the property of the spatially dominant soil series may provide the 'most likely' answer, but this may not be the most helpful answer for the end user. Additionally, when aggregating to select the dominant property or class, rather than the dominant taxonomic soil series, it is not uncommon for the 'dominant' class to change. One example of our new approach is to communicate the attributes of the soil associations on the basis of the worst-case scenario at various confidence levels, based on the percentage of the soil series of the association. As an example, when soil maps are used to help underwriters understand the vulnerability of an area to soil related subsidence, the maximum subsidence rating can be chosen from soils which comprise, for example, more than 5% or more than 30% of the soil association in question. Developing an understanding of end-user requirements allows optimization of soil datasets to suit their needs, and encourages engagement between soil scientists and industry.

Farewell, Timothy

2014-05-01

229

Quantifying the impact of livestock grazing on soil physical properties  

NASA Astrophysics Data System (ADS)

Livestock grazing is considered to have a noticeable influence on soil properties, when pedocompaction / soil pore reduction induced either by cattle or sheeps may curtail water residence time and accelerate the beginning and volume of overland flow. However, direct measurements of soil physical parameters and their changes under different pastoral management are seldom reported in central European conditions. Knowledge about these alterations are indispensable for setting the proper, soil and water conservative grazing management in the view of increasing areas of pastures, not only in the Czech Republic. Impact of cattle grazing on changes of soil properties was studied in three experimental upland catchments in the Czech Republic, differing in soil characteristics and grazing management. Values of soil saturated hydraulic conductivity (Ks), assessed three times a year in-situ during 2012 - 2013 with pressure infiltrometers, were compared for grazed and ungrazed cambisols, pseudogleys and gleysols, for grazing intensity ranging from 0.5 to 2 Livestock units / ha. Soil bulk density (BD) and macroporosity (MP) were determined before and after grazing season every year with ring 100 cm3 steel cyllinders. These parameters were measured also on heavily treaded plots by cattle - hotspots - in each catchment. Ks values on grazed plots were significantly lower (on average by 39 - 66 %) than on ungrazed sites, BD values were reduced on average by 15 % and MP values were lower roughly about 22 % on grazed plots. Ks values on hotspots were lower by 50 - 90 %, BD values by 5 - 18 % and MP values by 8 - 28 % comparing to the rest of grazed areas. Decrease of soil infiltration capacity was influenced by grazing intensity and soil characteristics. The greatest reductions concerning infiltration capacity were manifested in soils being periodically waterlogged (either by surface or by groundwater). A profound influence on the infiltration process was revealed in pasture soils rich on biotite, which together with clay minerals and the pseudogleyization process created an almost unpermeable layer, somewhere already in 25 cm below the surface. Off the grazing season, soils were recovering and in spring reached nearly similar properties, except for the hotspots, concerning the infiltration ability, as ungrazed soils. This research was supported by Czech Ministry of Agriculture, grant no. QI111C034.

Fu?ík, Petr; Zají?ek, Antonín; Holubík, Ond?ej

2014-05-01

230

Porosity factors that control the hydraulic conductivity of soil-saprolite transitional zones  

USGS Publications Warehouse

Slowly permeable transitional horizons separate soil and saprolite, but these horizons cannot be identified easily in the field. The objectives of this study were to determine why the soil-saprolite transitional zone (BC and CB horizons) is slowly permeable, and to evaluate ways for identifying it in the field. Two saprolite deposits were studied in the North Carolina Piedmont. At each site, saturated and unsaturated hydraulic conductivities (Ksat and Kunsat) were measured for major horizons. Volume fractions of water-conducting pores were also compared with the changes in hydraulic conductivity with depth. Horizon mean Ksat values at both sites ranged from virtually 0 to approximately 3 cm h-1. The lowest Ksat values (<0.3 cm h-1) occurred in or near the transitional horizons that were directly below the Bt horizons. Changes in the volume of pores within or between mineral grains (termed inter/intraparticle pores) with depth corresponded to changes in both Ksat and Kunsat. In the transitional horizons, the inter/intraparticle pores were plugged with clay and this caused the horizons to have low K values. In situ measurements of Ksat with depth were the most accurate technique to use for identifying transitional zones in the field. Examination of both the soil and rock structures in pits was also an acceptable technique. Texture and consistence were not considered reliable for pin-pointing transitional horizons.

Vepraskas, M.J.; Guertal, W.R.; Kleiss, H.J.; Amoozegar, A.

1996-01-01

231

Coarse fragments affects soil properties in a mantled-karst landscape of the Ozark Highlands  

Technology Transfer Automated Retrieval System (TEKTRAN)

This paper investigates the effect of rock fragments on soil physical hydraulic properties within the mantled karst landscapes of the Savoy Experimental Watershed (SEW), a setting typical of much of the Ozark Plateaus. Water resources in these settings are highly susceptible to contamination. As a r...

232

Hydraulic conducttince and soil water potential at the soil-root interface of Pinus pinaster seedlings inoculated with different dikaryons of Pisolithus sp  

Microsoft Academic Search

Summary Seedlings of maritime pine (Pinus pinaster Ait.) were inoculated with different dikaryons of Pisolithus sp. from South Africa to determine the influence of extension of the extramatrical phase and diameter of the mycelial strands on water relations parameters including xylem water potential (Y',), soil water potential at the soil-root interface (Y,) and hydraulic conductance (&,) during and after a

MOHAMMED S. LAMHAMEDI; PIERRE Y. BERNIER; J. ANDRti FORTIN

233

1. 1. In this class, the two of us will teach you about hydraulics.  

E-print Network

. By applying hydraulics, we can understand flow properties, and analyze the transport of soil and substances to understanding the environment, a purpose for which hydraulics is useful. #12;Keywords Related terminology fluid

Takahashi, Ryo

234

Combining multi-objective optimization and bayesian model averaging to calibrate forecast ensembles of soil hydraulic models  

SciTech Connect

Most studies in vadose zone hydrology use a single conceptual model for predictive inference and analysis. Focusing on the outcome of a single model is prone to statistical bias and underestimation of uncertainty. In this study, we combine multi-objective optimization and Bayesian Model Averaging (BMA) to generate forecast ensembles of soil hydraulic models. To illustrate our method, we use observed tensiometric pressure head data at three different depths in a layered vadose zone of volcanic origin in New Zealand. A set of seven different soil hydraulic models is calibrated using a multi-objective formulation with three different objective functions that each measure the mismatch between observed and predicted soil water pressure head at one specific depth. The Pareto solution space corresponding to these three objectives is estimated with AMALGAM, and used to generate four different model ensembles. These ensembles are post-processed with BMA and used for predictive analysis and uncertainty estimation. Our most important conclusions for the vadose zone under consideration are: (1) the mean BMA forecast exhibits similar predictive capabilities as the best individual performing soil hydraulic model, (2) the size of the BMA uncertainty ranges increase with increasing depth and dryness in the soil profile, (3) the best performing ensemble corresponds to the compromise (or balanced) solution of the three-objective Pareto surface, and (4) the combined multi-objective optimization and BMA framework proposed in this paper is very useful to generate forecast ensembles of soil hydraulic models.

Vrugt, Jasper A [Los Alamos National Laboratory; Wohling, Thomas [NON LANL

2008-01-01

235

SOIL PHYSICAL PROPERTIES AND CROP PRODUCTIVITY OF AN ERODED SOIL AMENDED WITH CATTLE MANURE  

Microsoft Academic Search

Erosion changes soil properties, especially physical properties, mainly because it removes surface soil rich in organic materials and exposes lower soil layers. In 1988, a study was established to determine the effects of soil erosion and long-term manure applications on selected soil phys­ ical properties and corn (Zea mays L.) production. After 10 years of an­ nual manure applications, soil

Francisco J. Arriaga; Birl Lowery

2003-01-01

236

A hydraulic model is compatible with rapid changes in leaf elongation under fluctuating evaporative demand and soil water status.  

PubMed

Plants are constantly facing rapid changes in evaporative demand and soil water content, which affect their water status and growth. In apparent contradiction to a hydraulic hypothesis, leaf elongation rate (LER) declined in the morning and recovered upon soil rehydration considerably quicker than transpiration rate and leaf water potential (typical half-times of 30 min versus 1-2 h). The morning decline of LER began at very low light and transpiration and closely followed the stomatal opening of leaves receiving direct light, which represent a small fraction of leaf area. A simulation model in maize (Zea mays) suggests that these findings are still compatible with a hydraulic hypothesis. The small water flux linked to stomatal aperture would be sufficient to decrease water potentials of the xylem and growing tissues, thereby causing a rapid decline of simulated LER, while the simulated water potential of mature tissues declines more slowly due to a high hydraulic capacitance. The model also captured growth patterns in the evening or upon soil rehydration. Changes in plant hydraulic conductance partly counteracted those of transpiration. Root hydraulic conductivity increased continuously in the morning, consistent with the transcript abundance of Zea maize Plasma Membrane Intrinsic Protein aquaporins. Transgenic lines underproducing abscisic acid, with lower hydraulic conductivity and higher stomatal conductance, had a LER declining more rapidly than wild-type plants. Whole-genome transcriptome and phosphoproteome analyses suggested that the hydraulic processes proposed here might be associated with other rapidly occurring mechanisms. Overall, the mechanisms and model presented here may be an essential component of drought tolerance in naturally fluctuating evaporative demand and soil moisture. PMID:24420931

Caldeira, Cecilio F; Bosio, Mickael; Parent, Boris; Jeanguenin, Linda; Chaumont, François; Tardieu, François

2014-04-01

237

Lunar soil properties and soil mechanics  

NASA Technical Reports Server (NTRS)

The long-range objectives were to develop methods of experimentation and analysis for the determination of the physical properties and engineering behavior of lunar surface materials under in situ environmental conditions. Data for this purpose were obtained from on-site manned investigations, orbiting and softlanded spacecraft, and terrestrial simulation studies. Knowledge of lunar surface material properties are reported for the development of models for several types of lunar studies and for the investigation of lunar processes. The results have direct engineering application for manned missions to the moon.

Mitchell, J. K.; Houston, W. N.

1974-01-01

238

High-quality unsaturated zone hydraulic property data for hydrologic applications  

USGS Publications Warehouse

In hydrologic studies, especially those using dynamic unsaturated zone moisture modeling, calculations based on property transfer models informed by hydraulic property databases are often used in lieu of measured data from the site of interest. Reliance on database-informed predicted values has become increasingly common with the use of neural networks. High-quality data are needed for databases used in this way and for theoretical and property transfer model development and testing. Hydraulic properties predicted on the basis of existing databases may be adequate in some applications but not others. An obvious problem occurs when the available database has few or no data for samples that are closely related to the medium of interest. The data set presented in this paper includes saturated and unsaturated hydraulic conductivity, water retention, particle-size distributions, and bulk properties. All samples are minimally disturbed, all measurements were performed using the same state of the art techniques and the environments represented are diverse.

Perkins, K.; Nimmo, J.

2009-01-01

239

Soil properties and water regime of reclaimed surface dumps in the North Bohemian brown-coal region--a field study.  

PubMed

This paper attempts to characterise the water regime of reclaimed surface dumps in connection with their soil physical properties. The results of a research project based on field measurements of moisture content and hydraulic conductivity, supported by analyses of undisturbed soil samples, led to recommendations regarding technological procedures for such dumps. A dielectric soil moisture meter, in an improved version, was successfully used for field monitoring and further evaluation of moisture content. Hydraulic conductivity was also measured in the field (by repeated borehole infiltration) using the Guelph permeameter method. Laplace-Gardner analysis was used for evaluating the field saturated hydraulic conductivity results. PMID:11220179

Kuráz, V

2001-01-01

240

Hydraulic Lift Increases Herbivory by Diaprepes abbreviatus Larvae and Persistence of Steinernema riobrave in Dry Soil  

PubMed Central

Citrus seedlings were grown in double pots that separated the root systems into discrete lower and upper zones to test the hypothesis that hydraulic lift affects persistence and efficacy of entomopathogenic nematodes. Three treatments were established: (i) both pots were irrigated at water potential ? -15 kPa (no drought); (ii) only the bottom pot was irrigated (partial drought); (iii) neither pot was irrigated (complete drought). Steinernema riobrave infective juveniles (IJ) were added to the soil in the top pots of all treatments. During 27 days, the water potential in soil in the top pots of both the partial and complete drought treatments declined to ca. -160 kPa. A greater number of nematodes (P ? 0.01) persisted in soil as motile IJ under conditions of partial drought (143/pot) than under no drought (6.1/pot) or complete drought (4.4/pot). A second experiment was initiated with the same treatments as the first, except that only half of the 20 replicates in each moisture regime were inoculated with nematodes. After 15 days, all top pots were irrigated and two larvae of the insect Diaprepes abbreviatus were added to all of the top pots in each treatment. Irrigation regimes were reinstituted until water potential in the top pots under partial and complete drought had again declined to ca. -150 kPa and the experiment was terminated. In the absence of nematodes, the damage to tap roots caused by D. abbreviatus feeding under partial drought and complete drought was 80% and 32%, respectively, of that under no drought. Numbers of motile IJ in soil were greater under conditions of partial drought (736/pot) than under complete drought (2.0/pot) or no drought (7.2/pot). Survival of D. abbreviatus and insect damage to roots were reduced by the presence of S. riobrave to a greater extent under partial drought as compared to other treatments. Hydraulic lift from the lower to the upper rhizosphere appears to have modulated the effect of dry soil conditions on feeding behavior of D. abbreviatus and created favorable conditions for persistence and efficacy of the entomopathogenic nematode. PMID:19266011

Duncan, L. W.; McCoy, C. W.

2001-01-01

241

Influence of leaf water status on stomatal response to humidity, hydraulic conductance, and soil drought in Betula occidentalis  

Microsoft Academic Search

Whole-canopy measurements of water flux were used to calculate stomatal conductance (gs) and transpiration (E) for seedlings of western water birch (Betula occidentalis Hook.) under various soil-plant hydraulic conductances (k), evaporative driving forces (?N; difference in leaf-to-air molar fraction of water vapor), and soil water potentials (?s). As expected, gs dropped in response to decreased k or ?S, or increased

Nicanor Z. Saliendra; John S. Sperry; Jonathan P. Comstock

1995-01-01

242

Soil physical properties and banana root growth  

Microsoft Academic Search

The physical properties of the soil regulate the conditions in which banana roots grow; therefore, they should be among the criteria evaluated to determine the soil's potential for banana production. Under adequate nutritional conditions and with a good water supply (rain or irrigation), banana roots require aeration and low mechanical resistance for normal growth. Therefore, the physical characteristics that affect

Roque Vaquero M

243

Mechanical properties testing of sheet metal by hydraulic bulge test  

NASA Astrophysics Data System (ADS)

The understanding of material characterization is necessary for metal forming process because the characteristic of material was directly related to the die designs. The die designers could adopt their knowledge to choose the appropriate material and realize the formability of material using in the process. Furthermore, they could understand when the undesired phenomena occurred during the forming process. Normally, the tensile test has been used to determine the characteristic of the material because this method was easy and cheap. However, the drawback of this tensile test is the leak of reasonable result because the specimen was deformed in only one direction, which is not coherence to the real forming process. In the practical process, the deformation of material was complicate and required the suitable experiment to describe the phenomenon of metal forming. Therefore, this research studied the formability of sheet metal by hydraulic bulge test. The sheet metal used in automobile industries was employed. The circular specimen was installed on the hydraulic bulge test machine, and the hydraulic system provided the pressure to form the specimens into the dome shape. Then the height of the dome was continuously increased until it broke. Based on this experiment, the dome height and forming pressure were used to characterize the relationship of stress and strain of material. The results obtained from this study revealed that the characteristic of material was more reliable and coherence to the sheet metal forming process.

Dimarn, Autthasit; Thanadngarn, Charn; Buakaew, Vichit; Neamsup, Yongyuth

2014-06-01

244

Hydraulic properties of three types of glacial deposits in Ohio  

USGS Publications Warehouse

The effects of thickness, grain size, fractures, weathering, and atmosphericconditions on vertical ground-water flow in glacial deposits were studied at three sites that represent ground moraine, end moraine, and lacustrine depositional environments. Vertical hydraulic conductivities computed from pumped-well tests were 3.24 x 10-1 to 6.47 x 10-1 ft/d (feet per day) at the site representing end moraine and 1.17 ft/d at the site representing lacustrine deposits. Analysis of test data for the ground moraine site did not yield estimates of hydraulic conductivities, but did indicate that ground water flows through the total thickness of deposits in response to discharge from a lower gravel unit. Vertical hydraulic conductivities computed from pumped-well tests of nested wells and data from drill-core analyses indicate that fractures affect the migration of ground water downward through the glacial deposits at these sites. Flow through glacial deposits is complex; it is controlled by fractures, gram-size distribution, clay content, thickness, and degree of weathering, and atmospheric conditions.

Strobel, M.L.

1993-01-01

245

Estimating hydraulic properties from tidal attenuation in the Northern Guam Lens Aquifer, territory of Guam, USA  

USGS Publications Warehouse

Tidal-signal attenuations are analyzed to compute hydraulic diffusivities and estimate regional hydraulic conductivities of the Northern Guam Lens Aquifer, Territory of Guam (Pacific Ocean), USA. The results indicate a significant tidal-damping effect at the coastal boundary. Hydraulic diffusivities computed using a simple analytical solution for well responses to tidal forcings near the periphery of the island are two orders of magnitude lower than for wells in the island’s interior. Based on assigned specific yields of ~0.01–0.4, estimated hydraulic conductivities are ~20–800 m/day for peripheral wells, and ~2,000–90,000 m/day for interior wells. The lower conductivity of the peripheral rocks relative to the interior rocks may best be explained by the effects of karst evolution: (1) dissolutional enhancement of horizontal hydraulic conductivity in the interior; (2) case-hardening and concurrent reduction of local hydraulic conductivity in the cliffs and steeply inclined rocks of the periphery; and (3) the stronger influence of higher-conductivity regional-scale features in the interior relative to the periphery. A simple numerical model calibrated with measured water levels and tidal response estimates values for hydraulic conductivity and storage parameters consistent with the analytical solution. The study demonstrates how simple techniques can be useful for characterizing regional aquifer properties.

Rotzoll, Kolja; Gingerich, Stephen B.; Jenson, John W.; El-Kadi, Aly I.

2013-01-01

246

Role of precipitation uncertainty in the estimation of hydrologic soil properties using remotely sensed soil moisture in a semi-arid environment 1891  

Technology Transfer Automated Retrieval System (TEKTRAN)

The focus of this study is the role of precipitation uncertainty in determining the accuracy and retrieveability of estimated soil texture and hydraulic properties. This work builds on and extends recent work conducted as part of the ongoing development of the Army Remote Moisture System (ARMS), in...

247

Effects of surfactants and electrolyte solutions on the properties of soil  

NASA Astrophysics Data System (ADS)

Biosurfactants are frequently used in petroleum hydrocarbon and dense non-aqueous phase liquids (DNAPLs) remediation. The applicability of biosurfactant use in clayey soils requires an understanding and characterization of their interaction. Comprehensive effects of surfactants and electrolyte solutions on kaolinite clay soil were investigated for index properties, compaction, strength characteristics, hydraulic conductivities, and adsorption characteristics. Sodium dodecyl sulfate (SDS) and NaPO3 decreased the liquid limit and plasticity index of the test soil. Maximum dry unit weights were increased and optimum moisture contents were decreased as SDS and biosurfactant were added for the compaction tests for mixtures of 30% kaolinite and 70% sand. The addition of non-ionic surfactant, biosurfactant, and CaCl2 increased the initial elastic modulus and undrained shear strength of the kaolinite-sand mixture soils. Hydraulic conductivities were measured by fixed-wall double-ring permeameters. Results showed that the hydraulic conductivity was not significantly affected, but slightly decreased from 1×10-7 cm/s (water) to 0.3×10-7 cm/s for Triton X-100 and SDS. The adsorption characteristics of the chemicals onto kaolinite were also investigated by developing isotherm curves. SDS adsorbed onto soil particles with the strongest bonding strength of the fluids tested. Correlations among parameters were developed for surfactants, electrolyte solutions, and clayey soils.

Park, Junboum; Vipulanandan, Cumaraswamy; Kim, Jee Woong; Oh, Myoung Hak

2006-04-01

248

FIELD AND LABORATORY METHODS IN SOIL SCIENCE  

E-print Network

· Measure fundamental soil chemical properties · Measure fundamental soil biological properties · Analyse analysis. Each week, laboratory measurements will be made (or initiated) or additional field measurements hydraulic conductivity (auger hole method) Infiltrability (tension infiltrometers, ring infiltrometers

Farrell, Anthony P.

249

Regional estimation of catchment-scale soil properties by means of streamflow recession analysis for use in distributed hydrological models  

NASA Astrophysics Data System (ADS)

The estimation of catchment-scale soil properties, such as water storage capacity and hydraulic conductivity, is of primary interest for the implementation of distributed hydrological models at the regional scale. This estimation is generally done on the basis of information provided by soil databases. However, such databases are often established for agronomic uses and generally do not document deep weathered rock horizons (i.e. pedologic horizons of type C and deeper), which can play a major role in water transfer and storages. Here we define the Drainable Storage Capacity Index (DSCI), an indicator that relies on the comparison of cumulated streamflow and precipitation to assess catchment-scale storage capacities. The DSCI is found to be reliable to detect underestimation of soil storage capacities in soil databases. We also use the streamflow recession analysis methodology defined by Brutsaert and Nieber (Water Resources Research 13(3), 1977) to estimate water storage capacities and lateral saturated hydraulic conductivities of the non-documented deep horizons. The analysis is applied to a sample of twenty-three catchments (0.2 km² - 291 km²) located in the Cévennes-Vivarais region (south of France). In a regionalisation purpose, the obtained results are compared to the dominant catchments geology. This highlights a clear hierarchy between the different geologies present in the area. Hard crystalline rocks are found to be associated to the thickest and less conductive deep soil horizons. Schist rocks present intermediate values of thickness and of saturated hydraulic conductivity, whereas sedimentary rocks and alluvium are found to be the less thick and the most conductive. Consequently, deep soil layers with thicknesses and hydraulic conductivities differing with the geology were added to a distributed hydrological model implemented over the Cévennes-Vivarais region. Preliminary simulations show a major improvement in terms of simulated discharge when compared to simulations done without deep soil layers. KEY WORDS: hydraulic soil properties, streamflow recession, deep soil horizons, soil databases, Boussinesq equation, storage capacity, regionalisation

Vannier, Olivier; Braud, Isabelle; Anquetin, Sandrine

2013-04-01

250

Impact of soil properties on selected pharmaceuticals adsorption in soils  

NASA Astrophysics Data System (ADS)

The presence of human and veterinary pharmaceuticals in the environment has been recognized as a potential threat. Pharmaceuticals may contaminate soils and consequently surface and groundwater. Study was therefore focused on the evaluation of selected pharmaceuticals adsorption in soils, as one of the parameters, which are necessary to know when assessing contaminant transport in soils. The goals of this study were: (1) to select representative soils of the Czech Republic and to measure soil physical and chemical properties; (2) to measure adsorption isotherms of selected pharmaceuticals; (3) to evaluate impact of soil properties on pharmaceutical adsorptions and to propose pedotransfer rules for estimating adsorption coefficients from the measured soil properties. Batch sorption tests were performed for 6 selected pharmaceuticals (beta blockers Atenolol and Metoprolol, anticonvulsant Carbamazepin, and antibiotics Clarithromycin, Trimetoprim and Sulfamethoxazol) and 13 representative soils (soil samples from surface horizons of 11 different soil types and 2 substrates). The Freundlich equations were used to describe adsorption isotherms. The simple correlations between measured physical and chemical soil properties (soil particle density, soil texture, oxidable organic carbon content, CaCO3 content, pH_H2O, pH_KCl, exchangeable acidity, cation exchange capacity, hydrolytic acidity, basic cation saturation, sorption complex saturation, salinity), and the Freundlich adsorption coefficients were assessed using Pearson correlation coefficient. Then multiple-linear regressions were applied to predict the Freundlich adsorption coefficients from measured soil properties. The largest adsorption was measured for Clarithromycin (average value of 227.1) and decreased as follows: Trimetoprim (22.5), Metoprolol (9.0), Atenolol (6.6), Carbamazepin (2.7), Sulfamethoxazol (1.9). Absorption coefficients for Atenolol and Metoprolol closely correlated (R=0.85), and both were also related to absorption coefficients of Carbamazepin (R=0.67 and 0.68). Positive correlation was found between Trimetoprim absorption coefficients and Atenolol, Metoprolol or Carbamazepin absorption coefficients. The negative relationship was found between absorption coefficients of Sulfomethoxazol and Clarithromycin (R=-0.80). Sulfamethoxazol absorption coefficient was negatively related to pH_H2O, pH_KCL or sorption complex saturation and positively to the hydrolytic acidity or exchangeable acidity. Trimetoprim absorption coefficient was positively related to the oxidable organic carbon content, cation exchange capacity, basic cation saturation or silt content and negatively to particle density or sand content. Clarithromycin absorption coefficient was positively related to pH_H2O, pH_KCL, CaCO3 content, basic cation saturation or sorption complex saturation and negatively to hydrolytic acidity or exchangeable acidity. Atenolol and Metoprolol absorption coefficients were positively related to the oxidable organic carbon content, cation exchange capacity, basic cation saturation, salinity, clay content or silt content, and negatively to the particle density or sand content. Finally Carbamazepin absorption coefficient was positively related to the oxidable organic carbon content, cation exchange capacity or basic cation saturation, and negatively to the particle density or sand content. Evaluated pedotransfer rules for different pharmaceuticals included different sets of soil properties. Absorption coefficients could be predicted from: the hydrolytic acidity (Sulfamethoxazol), the oxidable organic carbon content (Trimetoprim and Carbamazepin), the oxidable organic carbon content, hydrolytic acidity and cation exchange capacity (Clarithromycin), the basic cation saturation (Atenolol and Metoprolol). Acknowledgement: Authors acknowledge the financial support of the Czech Science Foundation (Project No. 13-12477S).

Kodesova, Radka; Kocarek, Martin; Klement, Ales; Fer, Miroslav; Golovko, Oksana; Grabic, Roman; Jaksik, Ondrej

2014-05-01

251

Development of a New Apparatus for Investigating Acoustic Effects on Hydraulic Properties of Low-Permeability Geo-Materials  

NASA Astrophysics Data System (ADS)

Remediation of polluted soils and groundwater contaminated by heavy metals and non-aqueous phase liquids has been one of the challenging issues in the field of geo-environments. In-situ removal of the contaminants from low permeable soils, such as clay strata, is particularly difficult because of the low mobility, strong adsorption, and/or other various interactions within soils. Thus current remediation techniques, such as pump- and-treat method and even eletrokinetic method, generally suffer from low recovery rates and/or economically unacceptable long remediation periods. A perspective improvement in remediation technology is to couple the electrokinetic method with an application of acoustic waves. This so-called Electro-Acoustic Soil Decontamination (EASD) method has been proposed by Battelle Columbus Labs.(Muralidhara et al. 1990). Simultaneous application of an electric field and an acoustic field may produce a synergistic effect and result in further enhancement of water transport by electro-osmosis in principle, but there is still no fundamental data for the design of EASD method in practical applications. A number of investigations have shown that an application of acoustic waves can increase hydraulic conductivity and mobility of non-aqueous phase liquids in porous media. Most of the prior and ongoing researches in this area have been focused on increasing production from declining oil and gas reservoirs. During several field tests by the oil and gas industries, increases in oil production rates by 20% or more have been reported. However, underlying physical mechanisms for acoustically enhanced fluid transport are not adequately understood. In addition, majority of the past investigations has dealt with applications of large amplitude of acoustic waves to relatively permeable soils or fractured rocks, and there is little information if acoustic wave effectively enhances flow and contaminant transport for less permeable clayey soils. To evaluate the feasibility of the EASD method and to obtain the fundamental but important knowledge for the design of this method, it is first necessary to understand the effects of acoustic wave application on pore water flow behavior. A new apparatus is developed to investigate the effects of acoustic wave on hydraulic properties of soil sample. This test apparatus enables to confine a cylindrical specimen under hydrostatic pressure conditions and to apply acoustic wave simultaneously. Preliminary results associated with the effects of acoustic wave frequency on changes of permeability of kaolin clay samples are illustrated in this report. A program investigating the effects of electricity and pore water chemistry on efficiency of decontamination using the same samples is also ongoing and briefly presented. The two strategies for enhancing the efficiency of remediation for low permeable soils will be combined in the near future

Nakajima, H.; Sawada, A.; Sugita, H.; Takeda, M.; Komai, T.; Zhang, M.

2006-12-01

252

Effect of cryogel on soil properties  

NASA Astrophysics Data System (ADS)

Samples from the A1 and A1A2 horizons of sandy loamy gray forest soil containing 3.1% organic matter have been mixed with a 5% solution of polyvinyl alcohol (PVA) at a ratio of 7 : 1 under laboratory conditions. The samples were frozen at -20°C in a refrigerator; after a freezing-thawing cycle, the evaporation of water from their surface, their thermal conductivity coefficient, their elasticity modulus, and other properties were studied. It has been experimentally found that the thermal conductivity coefficient of cryostructured soil is lower than that of common soil by 25%. It has been shown that the cryostructured soil retains water for a longer time and that the water evaporation rate from its surface is significantly lower compared to the control soil. Cryogel has no negative effect on the catalase activity of soil; it changes the physical properties of soils and positively affects the population of indigenous soil microflora and the growth of the sown plants.

Altunina, L. K.; Fufaeva, M. S.; Filatov, D. A.; Svarovskaya, L. I.; Rozhdestvenskii, E. A.; Gan-Erdene, T.

2014-05-01

253

Soil Properties Influence Distribution of Extractable Boron in Soil Profile  

Microsoft Academic Search

Depth distribution of boron (B) extractable by hot calcium chloride (HCC), potassium dihydrogen phosphate (PDP), and tartaric acid (TA) in some typical B?deficient Inceptisols, Entisols, and Alfisols in relation to soil properties was studied. The magnitude of B extraction followed the order HCC > PDP > TA for Inceptisols, TA > HCC > PDP for Entisols, and PDP > HCC

Dibyendu Sarkar; Biswapati Mandal; Manik Chandra Kundu; Javid Ahmad Bhat

2008-01-01

254

Determination of mechanical and hydraulic properties of PVA hydrogels.  

PubMed

In this paper the identification of mechanical and hydraulic parameters of poly(vinyl alcohol) (PVA) hydrogels is described. The identification method follows the solution of inverse problem using experimental data from the unconfined compression test and the poroelastic creep model. The sensitivity analysis of the model shows significant dependence of the creep curves on investigated parameters. The hydrogels containing 22% PVA and 25% PVA were tested giving: the drained Youngs modulus of 0.71 and 0.9MPa; the drained Poisson's ratio of 0.18 and 0.31; and the permeability of 3.64·10(-15) and 3.29·10(15)m(4)/Ns, respectively. The values of undrained Youngs modulus were determined by measuring short period deformation of samples in the unconfined tests. A discussion on obtained results is presented. PMID:25579895

Kazimierska-Drobny, Katarzyna; El Fray, Miroslawa; Kaczmarek, Mariusz

2015-03-01

255

UNSATURATED SOIL HYDRAULIC PROPERTIES FROM REDISTRIBUTION OF INJECTED WATER  

EPA Science Inventory

An analytical and experimental investigation of a matching method for the determination of the parameters in the Brooks-Corey K(h) and h(theta) relationships is presented. The method is based upon fitting an analytically derived response function to the corresponding measured one...

256

Three-dimensional structure of a highly heterogeneous horizon described by Electrical Resistivity Tomography: consequences on the determination of effective hydraulic properties  

NASA Astrophysics Data System (ADS)

Despite the increasing demand of soil hydraulic properties as input data for soil-plant-atmosphere models, the estimation of hydraulic properties in heterogeneous horizons remains a challenge. One reason is the lack of knowledge of the structure of such horizons, which limits the estimation of effective hydraulic properties at small scale. The aim of this paper is to demonstrate the interest of 3-D Electrical Resistivity Tomography (ERT) to describe the soil structure and to identify the Representative Elementary Volume of a heterogeneous horizon. The studied soil is an Albeluvisol that exhibits some horizons composed by the juxtaposition of two Elementary Pedological Volumes (EPVs); they can be visually distinguished by their colours (ochre and white) and they have differential hydraulic functioning: the clayey ochre ones conduct less water than the loamy white ones. Local electrical resistivity measurements showed that the ochre and white EPVs could be identified by ERT. Several 3D ERTs with an interelectrode spacing equal to 3 cm were then conducted on a 1 m² surface : i) seven Wenner arrays (16 electrodes) spaced of 9 cm and four Wenner arrays (32 electrodes) spaced of 9 cm, perpendicular to the seven previous ones; ii) a square array of 32 electrodes spaced of 3 cm. After these measurements, a 6 cm slice of the studied horizon was removed and the electrical resistivity measurements were recorded again at this second depth, and the whole protocol was recorded a third time. Thanks to all these measurements, the decrease of resolution with depth could be corrected. The data were then interpreted by using the Res2DInv and the Res3DInv softwares by using different strategies: -a- each 2D ERT was interpreted independently and all the interpreted resistivity data were gathered to create a 3-D block by regular kriging, -b- the 3D square array was interpreted and the resulting interpreted data were added to the 2D previous ones, -c- all the apparent resistivity data were associated and interpreted as a whole dataset. We finally got several 3-D blocks of the electrical soil structure of the heterogeneous horizon (say the organisation of ochre and white volume) at a 1 cm resolution on a volume of about 0.5 cm3. These blocks were compared to the real structure described by photographs so that we selected the best one. Several two-dimensional cuts of different sizes were extracted from this 3D block so that we can simulate on them the hydraulic functioning of the horizon by the Hydrus2D software. The equivalent hydraulic properties of the horizon were determined on each 2D cut, especially the unsaturated hydraulic conductivity that requires the knowledge of the structure. We finally discussed the evolution of the equivalent hydraulic properties with the size of the electrical resistivity images and we identified the minimum size of the horizon that must be investigated to contain a Representative Elementary Volume as far as hydraulic properties are concerned.

Cousin, I.; Frison, A.; Samouëlian, A.; Bourennane, H.; Guérin, R.; Richard, G.

2009-04-01

257

Information content of slug tests for estimating hydraulic properties in realistic, high-conductivity aquifer scenarios  

E-print Network

the ultimate goal of determining aquifer properties such as hydraulic conductivity K and specific storage Ss and identifiability, we find that: (1) as noted by previous researchers, estimation of aquifer storage parameters-conductivity aquifer scenarios Michael Cardiff a, , Warren Barrash a , Michael Thoma a , Bwalya Malama b a Boise State

Barrash, Warren

258

LEACHING AND HYDRAULIC PROPERTIES OF RETORTED OIL SHALE INCLUDING EFFECTS FROM CODISPOSAL OF WASTEWATER  

EPA Science Inventory

The report discusses the development of methods and data on the leaching and hydraulic properties of solid residues from oil shale processing. A column test, the Equilibrated Soluble Mass (ESM) test, was developed as an aid to characterizing the chemical quality of the first leac...

259

Setting properties and sealing ability of hydraulic temporary sealing materials.  

PubMed

This study sought to investigate the setting progress and sealing ability of hydraulic temporary sealing materials used in endodontic treatment: Lumicon, Caviton, and HY-Seal. To evaluate setting progress, the materials were filled into glass tubes with one end sealed and immersed in water. After immersion, a measurement apparatus was inserted from the non-immersed end and the set area was determined by subtracting the unset area from the sample thickness. To evaluate sealing ability, materials were filled into glass tubes and divided into four groups based on different immersion times. Thermal cycling and dye penetration were performed. At 7 days, the setting depths of HY-Seal and Caviton were almost equivalent to full sample thickness, while that of Lumicon was only half of full sample thickness (p < 0.01). On sealing ability, Lumicon ranked the highest followed by Caviton, whereas HY-Seal was unstable (p < 0.01). These results suggested that there was no correlation between setting progress and sealing ability. PMID:18972791

Ogura, Yoko; Katsuumi, Ichiroh

2008-09-01

260

Quasi-steady centrifuge method for unsaturated hydraulic properties  

USGS Publications Warehouse

[1] We have developed the quasi-steady centrifuge (QSC) method as a variation of the steady state centrifuge method that can be implemented simply and inexpensively with greater versatility in terms of sample size and other features. It achieves these advantages by somewhat relaxing the criterion for steadiness of flow through the sample. This compromise entails an increase in measurement uncertainty but to a degree that is tolerable in most applications. We have tested this new approach with an easily constructed apparatus to establish a quasi-steady flow of water in unsaturated porous rock samples spinning in a centrifuge, obtaining measurements of unsaturated hydraulic conductivity and water retention that agree with results of other methods. The QSC method is adaptable to essentially any centrifuge suitable for hydrogeologic applications, over a wide range of sizes and operating speeds. The simplified apparatus and greater adaptability of this method expands the potential for exploring situations that are common in nature but have been the subject of few laboratory investigations. Copyright 2005 by the American Geophysical Union.

Caputo, M.C.; Nimmo, J.R.

2005-01-01

261

Scaling of material properties for Yucca Mountain: literature review and numerical experiments on saturated hydraulic conductivity  

SciTech Connect

A review of pertinent literature reveals techniques which may be practical for upscaling saturated hydraulic conductivity at Yucca Mountain: geometric mean, spatial averaging, inverse numerical modeling, renormalization, and a perturbation technique. Isotropic realizations of log hydraulic conductivity exhibiting various spatial correlation lengths are scaled from the point values to five discrete scales through these techniques. For the variances in log{sub 10} saturated hydraulic conductivity examined here, geometric mean, numerical inverse and renormalization adequately reproduce point scale fluxes across the modeled domains. Fastest particle velocities and dispersion measured on the point scale are not reproduced by the upscaled fields. Additional numerical experiments examine the utility of power law averaging on a geostatistical realization of a cross-section similar to the cross-sections that will be used in the 1995 groundwater travel time calculations. A literature review on scaling techniques for thermal and mechanical properties is included. 153 refs., 29 figs., 6 tabs.

McKenna, S.A.; Rautman, C.A.

1996-08-01

262

Soil characteristics and landcover relationships on soil hydraulic conductivity at a hillslope scale: A view towards local flood management  

NASA Astrophysics Data System (ADS)

There are surprisingly few studies in humid temperate forests which provide reliable evidence that soil permeability is enhanced under forests. This work addresses this research gap through a detailed investigation of permeability on a hillslope in the Eddleston Catchment, Scottish Borders UK, to evaluate the impact of land cover, superficial geology and soil types on permeability using measurements of field saturated hydraulic conductivity (Kfs) supported by detailed topsoil profile descriptions and counting of roots with diameters >2 mm. Kfs was measured at depth 0.04-0.15 m using a constant head well permeameter across four paired landcover sites of adjacent tree and intensely grazed grassland. The measured tree types were: 500-year-old mixed woodland; 180-year-old mixed woodland; 45-year-old Pinus sylvestris plantation; and 180-year-old Salix caprea woodland. The respective paired grids of trees and grassland were compared on similar soil texture and topography. This study highlights the significant impact of broadleaf woodland at a hillslope scale on Kfs in comparison to grassland areas: median Kfs values under 180-year-old S. caprea woodland (8 mm h-1), 180-year-old mixed woodland (119 mm h-1) and 500-year-old broadleaf woodland (174 mm h-1) were found to be respectively 8, 6 and 5 times higher than neighbouring grazed grassland areas on the same superficial geology. Further statistical analysis indicates that such Kfs enhancement is associated with the presence of coarse roots (>2 mm diameter) creating conduits for preferential flow and a deeper organic layer in the topsoil profile under woodlands. By contrast the P. sylvestris forest had only slightly higher (42 mm h-1), but not statistically different Kfs values, when compared to adjacent pasture (35 mm h-1). In the grassland areas, in the absence of course roots, the superficial geology was dominant in accounting for differences in Kfs, with the alluvium floodplain having a significantly lower median Kfs (1 mm h-1) than surrounding hillslope sites, which had a range of median Kfs from 21 to 39 mm h-1. The data were used to infer areas of runoff generation by comparing Kfs values with modelled 15 min maximum intensity duration rainfall with a 1 in 10 year return period. Infiltration prevailed in the 180- and 500-year-old mixed and broadleaf woodland, whereas some grassland areas and the floodplain were inferred to generate overland flow. The significantly higher Kfs under broadleaf mature forests suggests that planting broadleaf woodlands on hillslopes in clusters or as shelterbelts within grasslands would provide areas of increased capacity for rainfall infiltration and arrest runoff generation during flood-producing storm events.

Archer, N. A. L.; Bonell, M.; Coles, N.; MacDonald, A. M.; Auton, C. A.; Stevenson, R.

2013-08-01

263

Hydraulic testing around Room Q: Evaluation of the effects of mining on the hydraulic properties of Salado Evaporites  

SciTech Connect

Room Q is a 109-m-long cylindrical excavation in the Salado Formation at the Waste Isolation Pilot Plant (WIPP) site. Fifteen boreholes were drilled and instrumented around Room Q so that tests could be conducted to determine the effects of room excavation on the hydraulic properties of the surrounding evaporate rocks. Pressure-buildup and pressure-pulse tests were conducted in all of the boreholes before Room Q was mined. The data sets from only eight of the boreholes are adequate for parameter estimation, and five of those are of poor quality. Constant-pressure flow tests and pressure-buildup tests were conducted after Room Q was mined, producing eleven interpretable data sets, including two of poor quality. Pre-mining transmissivities interpreted from the three good-quality data sets ranged from 1 x 10{sup -15} to 5 x 10{sup -14} m{sup 2}/s (permeability-thickness products of 2 x 10{sup -22} to 9 x 10{sup -21} m{sup 3}) for test intervals ranging in length from 0.85 to 1.37 m. Pre-mining average permeabilities, which can be considered representative of undisturbed, far-field conditions, were 6 x 10{sup -20} and 8 x 10{sup -20} m{sup 2} for anhydrite, and 3 x 10{sup -22} m{sup 2} for halite. Post-mining transmissivities interpreted from the good-quality data sets ranged from 1 x 10{sup -16} to 3 x 10{sup -13} m{sup 2}/s (permeability-thickness products of 2 x 10{sup -23} to 5 x 10{sup -20} m{sup 3}). Post-mining average permeabilities for anhydrite ranged from 8 x 10{sup -20} to 1 x 10{sup -19} m{sup 2}. The changes in hydraulic properties and pore pressures that were observed can be attributed to one or a combination of three processes: stress reduction, changes in pore connectivity, and flow towards Room Q. The effects of the three processes cannot be individually quantified with the available data.

Domski, P.S.; Upton, D.T. [INTERA, Inc., Albuquerque, NM (United States); Beauheim, R.L. [Sandia National Laboratories, Albuquerque, NM (United States)

1996-03-01

264

Prototype Data Models and Data Dictionaries for Hanford Sediment Physical and Hydraulic Properties  

SciTech Connect

The Remediation Decision Support (RDS) project, managed by the Pacific Northwest National Laboratory (PNNL) for the U.S. Department of Energy (DOE) and the CH2M HILL Plateau Remediation Company (CHPRC), has been compiling physical and hydraulic property data and parameters to support risk analyses and waste management decisions at Hanford. In FY09 the RDS project developed a strategic plan for a physical and hydraulic property database. This report documents prototype data models and dictionaries for these properties and associated parameters. Physical properties and hydraulic parameters and their distributions are required for any type of quantitative assessment of risk and uncertainty associated with predictions of contaminant transport and fate in the subsurface. The central plateau of the Hanford Site in southeastern Washington State contains most of the contamination at the Site and has up to {approx}100 m of unsaturated and unconsolidated or semi-consolidated sediments overlying the unconfined aquifer. These sediments contain a wide variety of contaminants ranging from organic compounds, such as carbon tetrachloride, to numerous radionuclides including technetium, plutonium, and uranium. Knowledge of the physical and hydraulic properties of the sediments and their distributions is critical for quantitative assessment of the transport of these contaminants in the subsurface, for evaluation of long-term risks and uncertainty associated with model predictions of contaminant transport and fate, and for evaluating, designing, and operating remediation alternatives. One of the goals of PNNL's RDS project is to work with the Hanford Environmental Data Manager (currently with CHPRC) to develop a protocol and schedule for incorporation of physical property and hydraulic parameter datasets currently maintained by PNNL into HEIS. This requires that the data first be reviewed to ensure quality and consistency. New data models must then be developed for HEIS that are approved by the HTAG that oversees HEIS development. After approval, these new data models then need to be implemented in HEIS by the EDM before there is an actual repository for the data. This document summarizes modifications to previously developed data models, and new data models and data dictionaries for physical and hydraulic property data and parameters to be transferred to HEIS. A prototype dataset that conforms to the specifications of these recommended data models has been identified and processed, and is ready for transfer to CHPRC for inclusion in HEIS. Additional datasets are planned for transfer from PNNL to CHPRC in FY11.

Rockhold, Mark L.; Last, George V.; Middleton, Lisa A.

2010-09-30

265

SOIL MOISTURE RETENTION CHARACTERISTICS AT RD 838 OF I. G. N. P. STAGE -II  

E-print Network

. In many cases, soil water properties govern gas, solute and heat transport in the soil. Fundamental soil water properties include volumetric water content, soil water flux density, soil water potential and hydraulic conductivity while derived properties are the soil water diffusivity, sorptivity and macroscopic

Kumar, C.P.

266

Multi-Sensor Estimation of Claypan Soil Profile Properties  

Technology Transfer Automated Retrieval System (TEKTRAN)

Large quantities of data are needed to solve land use and soil management problems, yet lab analysis of soil data is costly and time consuming. Soil property sensors on mobile platforms have the capability to estimate soil properties at many more locations than reference lab measurements. The fusion...

267

DESIGN AND MANAGEMENT OF SUBSURFACE SOIL ABSORPTION SYSTEMS  

EPA Science Inventory

The results of two studies are reported: (1) the effects of construction practices upon soil hydraulic properties; and (2) field examination of the effects of operational strategies upon soil infiltration properties. The investigation of construction practices showed that heavy m...

268

Electrokinetic properties of soil minerals and soils modified with polyelectrolytes  

NASA Astrophysics Data System (ADS)

The formation features of nanoadsorption polyelectrolyte (PE) layers with the formation of a mineral-organic matrix on the surface of clay minerals and soils (kaolinite, montmorillonite, quartz sand, gray forest soil, and chernozemic soil) have been elucidated by direct adsorption measurements. It has been found that the experimental values for the limit adsorption of polyacrylamide (PAM) and polyacrylic acid (PAA) on all the minerals are significantly higher than the calculated values for the formation of a monolayer. This indicates adsorption on the surface of not only separate macromolecules but also secondary PE structures as packets or fibrils determining the cluster-matrix structure of the modified surface. The study of the electro-surface properties (electrophoretic mobility, electrokinetic potential, pH, and electroconductivity) of mineral and soil particles adsorption-modified with PEs has confirmed the differences in the adsorption mechanisms (from physical sorption to chemisorption) with the formation of surface compounds depending on the different polar groups of PEs and the mineral type.

Kurochkina, G. N.; Pinskii, D. L.; Haynos, M.; Sokolowska, Z.; Tsesla, I.

2014-07-01

269

Submitted to WRR 1 Use of hydraulic tests at different scales to characterize fracture network properties in  

E-print Network

Submitted to WRR 1 Use of hydraulic tests at different scales to characterize fracture network, hydraulic conductivity, fracture, anisotropy 1. INTRODUCTION Hard rocks and their associated aquifers occur properties in the weathered-fractured layer of a hard rock aquifer J.C. Maréchala,b* , B. Dewandela , K

Boyer, Edmond

270

Gravity-driven groundwater flow and slope failure potential 2. Effects of slope morphology, material properties, and hydraulic heterogeneity  

Microsoft Academic Search

Hillslope morphology, material properties, and hydraulic heterogeneities influence the role of groundwater flow in provoking slope instability. The authors evaluate these influences quantitatively by employing the elastic effective stress model and Coulomb failure potential concept described in their companion paper. Sensitivity analyses show that of four dimensionless quantities that control model results, slope profiles and hydraulic conductivity contrasts have the

Mark E. Reid; Richard M. Iverson

1992-01-01

271

Estimating hydraulic properties of volcanic aquifers using constant-rate and variable-rate aquifer tests  

USGS Publications Warehouse

In recent years the ground-water demand of the population of the island of Maui, Hawaii, has significantly increased. To ensure prudent management of the ground-water resources, an improved understanding of ground-water flow systems is needed. At present, large-scale estimations of aquifer properties are lacking for Maui. Seven analytical methods using constant-rate and variable-rate withdrawals for single wells provide an estimate of hydraulic conductivity and transmissivity for 103 wells in central Maui. Methods based on constant-rate tests, although not widely used on Maui, offer reasonable estimates. Step-drawdown tests, which are more abundantly used than other tests, provide similar estimates as constant-rate tests. A numerical model validates the suitability of analytical solutions for step-drawdown tests and additionally provides an estimate of storage parameters. The results show that hydraulic conductivity is log-normally distributed and that for dike-free volcanic rocks it ranges over several orders of magnitude from 1 to 2,500 m/d. The arithmetic mean, geometric mean, and median values of hydraulic conductivity are respectively 520, 280, and 370 m/d for basalt and 80, 50, and 30 m/d for sediment. A geostatistical approach using ordinary kriging yields a prediction of hydraulic conductivity on a larger scale. Overall, the results are in agreement with values published for other Hawaiian islands. ?? 2007 American Water Resources Association.

Rotzoll, K.; El-Kadi, A. I.; Gingerich, S.B.

2007-01-01

272

Hydraulic and Seismic Properties of Methane-Bearing Coal  

NASA Astrophysics Data System (ADS)

In the last 10 years, coalbed methane (CBM) has transformed from being a coal mine hazard to a low-risk source of long term dry natural gas. The benefit of this clean burning natural gas as an energy source in conjunction with vast amounts stored in coal basins has led to the development of an industry that produces CBM. Reduction of carbon emissions to the atmosphere through carbon dioxide injection into coal has added another benefit to the production of CMB, as carbon dioxide may be used to desorb methane from coal seams. In order to successfully produce CBM, more information is needed on the migration of methane through fractures and cleats and on the replacement of methane by carbon dioxide in the coal seam. Laboratory experiments are underway to address these questions. Tests on core samples are being performed under in-situ pressure to gain insights on processes occurring in CBM extraction and carbon dioxide sequestration. A variety of techniques are being used including measuring physical properties, electrical resistivity, and saturation and phase location using x-ray computed tomography. Simultaneously measurements of seismic waves are performed including P- and S-wave velocities as well as amplitudes of body waves as a function of methane and carbon dioxide concentration in coal. The results can be used to design an experiment to monitor time-lapse changes and thus the production of gas from a coal seam during methane production.

Kneafsey, T. J.; Gritto, R.; Tomutsa, L.

2002-12-01

273

Vertical distribution of soil saturated hydraulic conductivity and its influencing factors in a small karst catchment in Southwest China.  

PubMed

Saturated hydraulic conductivity (Ks) is one of the most important soil hydraulic parameters influencing hydrological processes. This paper aims to investigate the vertical distribution of Ks and to analyze its influencing factors in a small karst catchment in Southwest China. Ks was measured in 23 soil profiles for six soil horizons using a constant head method. These profiles were chosen in different topographical locations (upslope, downslope, and depression) and different land-use types (forestland, shrubland, shrub-grassland, and farmland). The influencing factors of Ks, including rock fragment content (RC), bulk density (BD), capillary porosity (CP), non-capillary porosity (NCP), and soil organic carbon (SOC), were analyzed by partial correlation analysis. The mean Ks value was higher in the entire profile in the upslope and downslope, but lower value, acting as a water-resisting layer, was found in the 10-20 cm soil depth in the depression. Higher mean Ks values were found in the soil profiles in the forestland, shrubland, and shrub-grassland, but lower in the farmland. These results indicated that saturation-excess runoff could occur primarily in the hillslopes but infiltration-excess runoff in the depression. Compared with other land-use types, surface runoff is more likely to occur in the farmlands. RC had higher correlation coefficients with Ks in all categories concerned except in the forestland and farmland with little or no rock fragments, indicating that RC was the dominant influencing factor of Ks. These results suggested that the vertical distributions of Ks and RC should be considered for hydrological modeling in karst areas. PMID:25663401

Fu, Tonggang; Chen, Hongsong; Zhang, Wei; Nie, Yunpeng; Wang, Kelin

2015-03-01

274

Properties and variability of soil and trench fill at an arid waste-burial site  

USGS Publications Warehouse

Arid sites commonly are assumed to be ideal for long-term isolation of wastes. Information on properties and variability of desert soils is limited, however, and little is known about how the natural site environment is altered by installation of a waste facility. During fall construction of two test trenches next to the waste faculty on the Amargosa Desert near Beatty, NV, samples were collected to: (i) characterize physical and hydraulic properties of native soil (upper 5 m) and trench fill, (ii) determine effects of trench construction on selected properties and vertical variability of these properties, and (iii) develop conceptual models of vertical variation within the soil profile and trench fill. Water retention was measured to air dryness (?? = 2 ?? 106 cm water suction). The 15 300-cm pressure-plate data were omitted from the analysis because water-activity measurements showed the actual suction values were significantly less than the expected 15 300-cm value (avg. difference = 8550 ?? 2460 cm water). Trench construction significantly altered properties and variability of the natural site environment. For example, water content ranged from 0.029 to 0.041 m3 m-3 for fill vs. 0.030 to 0.095 m3 m-3 for soil; saturated hydraulic conductivity was ???10-4 cm s-1 for fill vs. 10-2 to ???10-4 cm s-1 for soil. Statistical analyses showed that the native soil may be represented by three major horizontal components and the fill by a single component. Under initial conditions, calculated liquid conductivity (K1) plus isothermal vapor conductivity (Kv) for the upper two soil layers and the trench fill was ???10-13 cm s-1, and K1 was ??? Kv. For the deeper (2-5 m) soil, total conductivity was ???10-10 cm s-1, and K1 was > Kv. This study quantitatively describes hydraulic characteristics of a site using data measured across a water-content range that is representative of arid conditions, but is seldom studied.

Andraski, B.J.

1996-01-01

275

Tillage effects on Dryland Soil Physical Properties in Northeastern Montana  

Technology Transfer Automated Retrieval System (TEKTRAN)

A study was initiated in 2005 to evaluate the effect of no-till (NT) chemical fallow and conventional tillage (CT) fallow management on soil penetration resistance (PR), bulk density ('b), gravimetric water content (MC) and saturated hydraulic conductivity (Ks) in spring wheat fallow rotation under ...

276

The relationship of catchment topography and soil hydraulic characteristics to lake alkalinity in the northeastern United States  

USGS Publications Warehouse

The influence of topography and soils on catchment hydrology has been incorporated previously in the variable source area model TOPMODEL as the relative frequency distribution of In (a/Kb tan B), where In is the Naperian logarithm, "a' is the area drained per unit contour, K is the saturated hydraulic conductivity, b is the total depth, and tan B is the slope. Using digital elevation and soil survey data, the In (a/Kb tan B) distribution for 145 catchments was calculated. Indices of flow path partitioning and soil contact time were derived from the In (a/Kb tan B) distributions and compared to measurements of alkalinity in lakes to which the catchments drain. Alkalinity was, in general, positively correlated with the index of soil contact time, whereas the correlation between alkalinity and the flow path partitioning index was weak at best. A portion of the correlation between the soil contact time index and alkalinity was attributable to covariation with soil base saturation and cation exchange capacity, while another portion was found to be independent of these factors. -from Authors

Wolock, D.M.; Hornberger, G.M.; Beven, K.J.; Campbell, W.G.

1989-01-01

277

Fallow Effects on Improving Soil Properties and Decreasing Erosion: Atlantic Forest, Southeastern Brazil  

NASA Astrophysics Data System (ADS)

Soil tillage plays a major role in changing physical and hydrological properties of soils through time, and in consequence, in the dynamics of infiltration, soil water and erosion. In the hilly landscape of southeastern Brazil, many areas originally occupied by the Atlantic Forest (one the most threatened biomes on the planet) have been continuously transformed in the last decades into agricultural systems, usually associated with small farming properties. Traditionally, the agricultural activities in these areas incorporate rotational systems which include a fallow period, where previously farmed areas repose for at least five years. In some areas, vegetation grows so fast that after 7 or 8 years these sites may be considered by regulator agencies as forests, impeding their use again for farming. As a consequence, farmers tend to decrease the amount of time used fallow impeding the recovery of original soil properties, reducing in consequence the infiltration rate, and increasing the runoff and erosion. Currently, the Brazilian laws allow that the farmers use the fallow system for 10 years in areas where this technique has been used traditionally. So, a major issue here is for how long the farming plots should be left reposing. Therefore, this study aims both to characterize the effects of continuous farming on soil physical and hydrological properties, as well as to define the impacts of different fallow periods on the improvement of soil properties and in the reduction of runoff and erosion. The experiments were carried out in a cultivation site located at Bom Jardim city, close to Rio de Janeiro city. The area is situated at about 800m of elevation in the hilly steep topography of the Serra do Mar, a coast range in southeastern Brazil, with an average total annual rainfall of 2000 mm. In this study, carried out in a typical farm of the area, we compared the effects of 5 different soil usages on soil properties: banana, coffee, F2 (2-year fallow), F5 (5-year fallow) and forest. For each case, 12 soil samples were collected at 4 depths: 0-5, 5-10, 10-20 and 20-30cm, with 3 repetitions, leading to a total of 60 soil samples, where the following properties were characterized: porosity (micro, macro and total), bulk density and aggregate stability. Besides, in situ measurements of saturated hydraulic conductivity were conducted with a Guelph permeameter. The results obtained in this study attested that all the soil properties analyzed were affected by soil usage, especially at shallow depths, in particular macroporosity and total porosity, which have major influences on infiltration rates, runoff and soil erosion. Besides, the results suggested that the 5-year fallow (F5) was able to recover from 72% to 100% of total porosity for the 0-10cm depth layer (considering forest values as reference), while in the 2-year fallow (F2) this recovery was lower, ranging from 66 to 80%. A similar trend was observed for macroporosity, showing recovering values from 60% to 90% and from 50% to 76%, for F5 and F2, respectively. However, aggregate stability values did not show significant variations between the two fallows. Saturated hydraulic conductivity, on the other hand, presented the lowest recovering values for all the studied properties: between 13% and 58% for F5 and between 6% and 33% for F2. Comparing to the natural forest (reference value), the coffee plantations presented the worst soil conditions in terms of soil hydrology and erosion. The results presented here attested important improvements in soil physical and hydrological properties after a 5-year fallow, leading to decrease in surface runoff and soil erosion in the area.

Miranda, J. P.; Silva, L. M.; Lima, R. L.; Donagemma, G. K.; Bertolino, A. V. A.; Fernandes, N. F.; Correa, F. M.; Polidoro, J. C.; Tato, G.

2009-04-01

278

Enhanced biogeochemical cycling and subsequent reduction of hydraulic conductivity associated with soil-layer interfaces in the vadose zone.  

PubMed

Biogeochemical dynamics in the vadose zone are poorly understood due to the transient nature of chemical and hydrologic conditions but are nonetheless critical to understanding chemical fate and transport. This study explored the effects of a soil layer on linked geochemical, hydrological, and microbiological processes. Three laboratory soil columns were constructed: a homogenized medium-grained sand, a homogenized organic-rich loam, and a sand-over-loam layered column. Upward and downward infiltration of water was evaluated during experiments to simulate rising water table and rainfall events, respectively. In situ collocated probes measured soil water content, matric potential, and Eh. Water samples collected from the same locations were analyzed for Br, Cl, NO, SO, NH, Fe, and total sulfide. Compared with homogeneous columns, the presence of a soil layer altered the biogeochemistry and water flow of the system considerably. Enhanced biogeochemical cycling was observed in the layered column over the texturally homogeneous soil columns. Enumerations of iron- and sulfate-reducing bacteria showed 1 to 2 orders of magnitude greater community numbers in the layered column. Mineral and soil aggregate composites were most abundant near the soil-layer interface, the presence of which likely contributed to an observed order-of-magnitude decrease in hydraulic conductivity. These findings show that quantifying coupled hydrologic-biogeochemical processes occurring at small-scale soil interfaces is critical to accurately describing and predicting chemical changes at the larger system scale. These findings also provide justification for considering soil layering in contaminant fate and transport models because of its potential to increase biodegradation or to slow the rate of transport of contaminants. PMID:22031578

Hansen, David J; McGuire, Jennifer T; Mohanty, Binayak P

2011-01-01

279

Hydraulic Anisotropy Characterization Using Azimuthal Self Potential Gradient [ASPG]: Results from Pneumatic Fracturing of Tight Clay Soils  

NASA Astrophysics Data System (ADS)

Recent studies have shown that bulk hydraulic anisotropy associated with fractures in fractured rock aquifers can be inferred from Azimuthal Self Potential Gradient (ASPG) measurements. This extremely simple technique involves measuring the self potential gradient as a function of azimuth with a pair of non polarizing electrodes connected to a voltmeter. The electrokinetic effect associated with the flow of fluids within fractures is the source of the ASPG signal. Fracture strike mapping at multiple sites has repeatedly demonstrated the effectiveness of the method at the field scale and indicated that the direction of flow can be determined from the polarity of relatively large ASPG signals. A laboratory study was conducted to determine whether ASPG could also be used to characterize the hydraulic anisotropy associated with the enhancement of permeability and porosity of tight unconsolidated soils (e.g. clays) as a result of pneumatic fracturing, a technique to improve the effectiveness of remediation efforts. Compressed kaolinite sediments were pneumatically fractured following industry procedures. The resulting fracture geometry was quantified from strike analysis of visible fractures combined with strike data from optical borehole televiewer (BHTV) imaging. ASPG measurements were then made during injection of a simulated remedial treatment (electrolyte/dye) under an applied gas pressure. Consistent with previous findings in fractured rock aquifers, ASPG lobes are well correlated with azimuths of high fracture strike density suggesting that the ASPG anisotropy is a proxy measure of hydraulic anisotropy created by the pneumatic fracturing. The magnitude of the ASPG signal scales linearly (linear correlation coefficients > 0.74) with the applied gas pressure gradient for any particular hydraulically-active fracture set and the positive lobe of the ASP anomaly denotes the flow direction within that fracture set. These findings demonstrate that applications of the simple ASPG technique go beyond characterization of hydraulic anisotropy in fractured bedrock aquifers. As demonstrated here, the method can characterize hydraulic anisotropy artificially created in tight unconsolidated soils and could be used to monitor the progress of remedial treatments applied to contaminated environments.

Slater, L.; Wishart, D.; Schnell, D.; Hermann, G.

2008-12-01

280

Tillage system affects microbiological properties of soil  

NASA Astrophysics Data System (ADS)

Soil tillage significantly affects organic carbon accumulation, microbial biomass, and subsequently enzymatic activity in surface soil. Microbial activity in soil is a crucial parameter contributing to soil functioning, and thus a basic quality factor for soil. Since enzymes remain soil after excretion by living or disintegrating cells, shifts in their activities reflect long-term fluctuations in microbial biomass. In order to study the effects of no-till on biochemical and microbiological properties in comparison to conventional tillage in a representative soil from South Spain, an experiment was conducted since 1982 on the experimental farm of the Institute of Agriculture and Fisheries Research of Andalusia (IFAPA) in Carmona, SW Spain (37o24'07''N, 5o35'10''W). The soil at the experimental site was a very fine, montomorillonitic, thermic Chromic Haploxerert (Soil Survey Staff, 2010). A randomized complete block design involving three replications and the following two tillage treatments was performed: (i) Conventional tillage, which involved mouldboard plowing to a depth of 50 cm in the summer (once every three years), followed by field cultivation to a depth of 15 cm before sowing; crop residues being burnt, (ii) No tillage, which involved controlling weeds before sowing by spraying glyphosate and sowing directly into the crop residue from the previous year by using a planter with double-disk openers. For all tillage treatments, the crop rotation (annual crops) consisted of winter wheat, sunflower, and legumes (pea, chickpea, or faba bean, depending on the year), which were grown under rainfed conditions. Enzymatic activities (ß-glucosidase, dehydrogenase, aryl-sulphatase, acid phosphatase, and urease), soil microbial biomass by total viable cells number by acridine orange direct count, the density of cultivable groups of bacteria and fungi by dilution plating on semi-selective media, the physiological profiles of the microbial communities by BiologR, and the Shannon (H') and Gini (1-G) diversity index of microbial communities were determined in soil samples (0-10 cm depth) taken in autumn 2009. All the enzymatic activities and the biomass estimated by viable cell counting were significantly higher under no-till than under conventional tillage. However, only fluorescents pseudomonas population was increased under no-till, meanwhile oligotrophic bacteria and actinomycetes populations were higher with conventional tillage than with no-till. Overall, there was a higher use all the group of carbon sources used in the BiologR test with conventional tillage than with no-till, by except amines and phenols which showed non-significant differences. This reveals different physiological profiles in the microbial communities under both tillage systems. The Gini diversity was significantly lower with no-till than with conventional tillage. It can be concluded that no-till increases microbial biomass in soil and subsequently enzymatic activities likely ascribed to an increased organic matter content. Under low availability of hydrocarbon sources in soil due to conventional tillage, which promotes a decrease in the organic matter content of the soil, populations of oligotrophods and the diversity of microbial communities are increased. Under these conditions, there must not be dominant carbon sources promoting the selection of microorganisms with a given physiological profile. The reduced hydrocarbon availability and the higher diversity contribute to explain the increased use of carbon sources used in Biolog with conventional tillage than with no-till.

Delgado, A.; de Santiago, A.; Avilés, M.; Perea, F.

2012-04-01

281

Estimation of field-scale soil hydraulic and dielectric parametersthrough joint inversion of GPR and hydrological data  

SciTech Connect

A method is described for jointly using time-lapse multiple-offset cross-borehole ground-penetrating radar (GPR) travel time measurements and hydrological measurements to estimate field-scale soil hydraulic parameters and parameters of the petrophysical function, which relates soil porosity and water saturation to the effective dielectric constant. We build upon previous work to take advantage of a wide range of GPR data acquisition configurations and to accommodate uncertainty in the petrophysical function. Within the context of water injection experiments in the vadose zone, we test our inversion methodology with synthetic examples and apply it to field data. The synthetic examples show that while realistic errors in the petrophysical function cause substantial errors in the soil hydraulic parameter estimates,simultaneously estimating petrophysical parameters allows for these errors to be minimized. Additionally, we observe in some cases that inaccuracy in the GPR simulator causes systematic error in simulated travel times, making necessary the simultaneous estimation of a correction parameter. We also apply the method to a three-dimensional field setting using time-lapse GPR and neutron probe (NP) data sets collected during an infiltration experiment at the U.S. Department of Energy (DOE) Hanford site in Washington. We find that inclusion of GPR data in the inversion procedure allows for improved predictions of water content, compared to predictions made using NP data alone.

Kowalsky, Michael B.; Finsterle, Stefan; Peterson, John; Hubbard,Susan; Rubin, Yoram; Majer, Ernest; Ward, Andy; Gee, Glendon

2005-05-05

282

Quantitative relationships between soil macropore characteristics and preferential flow and transport  

Technology Transfer Automated Retrieval System (TEKTRAN)

Quantitative relationships between soil structure, especially macropore characteristics, and soil hydraulic properties are essential to improving our ability to predict flow and transport in structured soils. The objectives of this study were to quantitatively relate macropore characteristics to sat...

283

Relation between mass balance aperture and hydraulic properties from field experiments in fractured rock in Sweden  

NASA Astrophysics Data System (ADS)

Results from tracer tests are often used to infer connectivity and transport properties in bedrock. However, the amount of site-specific data from tracer tests is often very limited, while data from hydraulic tests are more abundant. It is therefore of great interest for predictive transport modeling to use hydraulic data to infer transport properties. In this study, data from cross-hole tracer tests carried out in crystalline bedrock in Sweden were compiled and analysed. The tests were performed within investigations made by the Swedish Nuclear Fuel and Waste Management Company (SKB) between 1978 and 2009 at five different locations. An empirical relationship between mass balance aperture and transmissivity was found and quantified by using 74 observations. The empirical relationship deviates considerably from the cubic law aperture, as mass balance aperture is found to be at least one order of magnitude larger than cubic law aperture. Hence, usage of cubic law aperture, derived from hydraulic testing, for transport predictions is unsuitable, as the advective transport time will be considerably underestimated. Another result, from the data set studied, is that mass balance aperture appears to correlate better to apparent storativity than to transmissivity.

Hjerne, Calle; Nordqvist, Rune

2014-09-01

284

Estimating hydraulic properties using a moving-model approach and multiple aquifer tests  

USGS Publications Warehouse

A new method was developed for characterizing geohydrologic columns that extended >600 m deep at sites with as many as six discrete aquifers. This method was applied at 12 sites within the Southwest Florida Water Management District. Sites typically were equipped with multiple production wells, one for each aquifer and one or more observation wells per aquifer. The average hydraulic properties of the aquifers and confining units within radii of 30 to >300 m were characterized at each site. Aquifers were pumped individually and water levels were monitored in stressed and adjacent aquifers during each pumping event. Drawdowns at a site were interpreted using a radial numerical model that extended from land surface to the base of the geohydrologic column and simulated all pumping events. Conceptually, the radial model moves between stress periods and recenters on the production well during each test. Hydraulic conductivity was assumed homogeneous and isotropic within each aquifer and confining unit. Hydraulic property estimates for all of the aquifers and confining units were consistent and reasonable because results from multiple aquifers and pumping events were analyzed simultaneously. Copyright ?? 2005 National Ground Water Association.

Halford, K.J.; Yobbi, D.

2006-01-01

285

Using bacterial bioluminescence to evaluate the impact of biofilm on porous media hydraulic properties.  

PubMed

Biofilm formation in natural and engineered porous systems can significantly impact hydrodynamics by reducing porosity and permeability. To better understand and characterize how biofilms influence hydrodynamic properties in porous systems, the genetically engineered bioluminescent bacterial strain Pseudomonas fluorescens HK44 was used to quantify microbial population characteristics and biofilm properties in a translucent porous medium. Power law relationships were found to exist between bacterial bioluminescence and cell density, fraction of void space occupied by biofilm (i.e. biofilm saturation), and hydraulic conductivity. The simultaneous evaluation of biofilm saturation and porous medium hydraulic conductivity in real time using a non-destructive approach enabled the construction of relative hydraulic conductivity curves. Such information can facilitate simulation studies related to biological activity in porous structures, and support the development of new models to describe the dynamic behavior of biofilm and fluid flow in porous media. The bioluminescence based approach described here will allow for improved understanding and control of industrially relevant processes such as biofiltration and bioremediation. PMID:25479429

Bozorg, Ali; Gates, Ian D; Sen, Arindom

2015-02-01

286

Linking Amazonian secondary succession forest growth to soil properties  

Microsoft Academic Search

The Amazon Basin has suffered extensive deforestation in the past 30 years. Deforestation typically leads to changes in climate, biodiversity, hydrological cycle, and soil degradation. Vegetation succession plays an important role in soil restoration through accumulation of vegetation biomass and improved soil\\/plant interaction. However, relationships between succession and soil properties are not well known. For example, how does vegetation succession

D. Lu; E. Moran; P. Mausel

2002-01-01

287

Space agriculture in micro- and hypogravity: A comparative study of soil hydraulics and biogeochemistry in a cropping unit on Earth, Mars, the Moon and the space station  

Microsoft Academic Search

Increasing interest is developing towards soil-based agriculture as a long-term bioregenerative life support during space and planetary explorations. Contrary to hydroponics and aeroponics, soil-based cropping would offer an effective approach to sustain food and oxygen production, decompose organic wastes, sequester carbon dioxide, and filter water. However, the hydraulics and biogeochemical functioning of soil systems exposed to gravities lower than the

Federico Maggi; Céline Pallud

2010-01-01

288

Importance of internal hydraulic redistribution for prolonging the lifespan of roots in dry soil  

Microsoft Academic Search

Redistribution of water within plants could mitigate drought stress of roots in zones of low soil moisture. Plant internal redistribution of water from regions of high soil moisture to roots in dry soil occurs during periods of low evaporative demand. Using minirhizotrons, we observed similar lifespans of roots in wet and dry soil for the grape- vine 'Merlot' (Vitis vinifera)

T. L. BAUERLE; D. M. EISSENSTAT

2008-01-01

289

Hydraulic lift: Substantial nocturnal water transport between soil layers by Artemisia tridentata roots  

Microsoft Academic Search

Diel soil water potential fluctuations reflected daytime depletion and nocturnal resupply of water in upper soil layers. Transpiration suppression experiments demonstrated that water absorption by roots caused the daytime depletion. The soil water potential data and experimental results suggest that at night water absorbed from moist soil by deeper roots is transported to and lost from roots into drier upper

J. H. Richards; M. M. Caldwell

1987-01-01

290

SOIL PROPERTY DATABASE: SOUTHERN GREAT PLAINS 1997 HYDROLOGY EXPERIMENT  

Technology Transfer Automated Retrieval System (TEKTRAN)

Many models used in land surface hydrology, vadose zone hydrology and hydroclimatology require an accurate representation of soil properties. Unfortunately, existing soil property databases are limited in terms of reliability, precision, and their usefulness in evolving soil-vegetation-atmosphere-t...

291

Effects of Soil Property and Soil Amendment on Weathering of Abraded Metallic Pb in Shooting Ranges  

E-print Network

that are present in Pb contaminated soils. Metallic Pb is unstable under typical soil conditions (Cao et al., 2003aEffects of Soil Property and Soil Amendment on Weathering of Abraded Metallic Pb in Shooting Ranges.V. 2006 Abstract Weathering of abraded metallic Pb from bullets is a significant source of Pb

Ma, Lena

292

Cotton Production Practices Change Soil Properties  

NASA Astrophysics Data System (ADS)

Historically, indigenous Asiatic cottons (Gossypium arboreum) were cultivated with minimal inputs in India. The introduction of the Upland cottons (G. hirsutum) and later the hybrid (H-4) triggered a whole set of intensified agronomic management with reliance on high doses of fertilisers and pesticide usage. In 2002, the transgenic Bt cotton hybrids were introduced and released for commercial cultivation. Presently, more than 95% of the nearly 12.2 million hectares of cotton area is under the Bt transgenic hybrids. These hybrids are not only high yielding but have reduced the dependence on pesticide because of an effective control of the lepidopteran pests. Thus, a change in the management practices is evident over the years. In this paper, we discuss the impact of two major agronomic management practices namely, nutrient management and tillage besides organic cotton cultivation in the rainfed cotton growing regions of central India characterized by sub-humid to semi-arid climate and dominated by Vertisols. Long-term studies at Nagpur, Maharashtra indicated the importance of integrated nutrient management (INM) wherein a part of the nutrient needs through fertiliser was substituted with organic manures such as farmyard manure (FYM). With the application of mineral fertilisers alone, soils became deficient in micronutrients. This was not observed with the FYM amended plots. Further, the manure amended plots had a better soil physical properties and the water holding capacity of the soil improved due to improvements in soil organic matter (SOM). Similarly, in a separate experiment, an improvement in SOM was observed in the organically managed fields because of continuous addition of organic residues. Further, it resulted in greater biological activity compared to the conventionally managed fields. Conservation tillage systems such as reduced tillage (RT) are a means to improve soil health and crop productivity. Long-term studies on tillage practices such as conventional tillage {CT}, RT with two inter-row cultivations {RT1} and RT with no inter-row cultivation {RT2} were conducted for 11 years. At the end of the study, an improvement in the soil physical properties such as water stable aggregates and mean weight diameter were observed in the RT system and the plots amended with green manure (GM) cover crop compared to those without. Further, available soil moisture content was greater in the GM mulched plots up to 0.60 m depth compared to the without GM treatment. The RT systems, too, had a higher SOM content than the CT probably due to less soil disturbance and greater retention of crop residues. INM and conservation tillage are strategies to sequester C and reduce emissions. It can also mitigate green house gas emissions because less of fertiliser would be used in the INM treatments. Studies conducted, thus far, have not indicated any adverse effect of Bt cotton cultivation. However, there could be a possibility, of nutrient depletion with the cultivation of Bt transgenic hybrids because of higher biomass and nutrient removal increasing the nutrient demand. Studies on these aspects are needed to understand how long-term cultivation of Bt cotton hybrids will alter the soil properties.

Blaise, D.; Singh, J. V.

2012-04-01

293

MODELING OF SOIL CATION EXCHANGE CAPACITY BASED ON SOME SOIL PHYSICAL AND CHEMICAL PROPERTIES  

Microsoft Academic Search

There are many cases in which it is desirable to determine relationships among some soil physical and chemical properties. For instance, soil cation exchange capacity (CEC) are often determined using laborious and time consuming laboratory tests, but it may be more suitable and economical to develop a method which uses some soil physical and chemical properties. Therefore, a relationship between

Majid Rashidi; Mohsen Seilsepour

294

Soil properties mapping with the DIGISOIL multi-sensor system  

NASA Astrophysics Data System (ADS)

The multidisciplinary DIGISOIL project aimed to integrate and improve in situ and proximal measurement technologies for the assessment of soil properties and soil degradation indicators, going from the sensing technologies to their integration and their application in (digital) soil mapping (DSM). In order to assess and prevent soil degradation and to benefit from the different ecological, economical and historical functions of the soil in a sustainable way, high resolution and quantitative maps of soil properties are needed. The core objective of the project is to explore and exploit new capabilities of advanced geophysical technologies for answering this societal demand. To this aim, DIGISOIL addresses four issues covering technological, soil science and economic aspects: (i) the validation of geophysical (in situ, proximal and airborne) technologies and integrated pedo-geophysical inversion techniques (mechanistic data fusion) (ii) the relation between the geophysical parameters and the soil properties, (iii) the integration of the derived soil properties for mapping soil functions and soil threats, (iv) the pre-evaluation, standardisation and sub-industrialization of the proposed methodologies, including technical and economical studies related to the societal demand. With respect to these issues, the DIGISOIL project allows to develop, test and validate the most relevant geophysical technologies for mapping soil properties. The system was tested on different field tests, and validated the proposed technologies and solutions for each of the identified methods: geoelectric, GPR, EMI, seismics, magnetic and hyperspectral. After data acquisition systems, sensor geometry, and advanced data processing techniques have been developed and validated, we present now the solutions for going from geophysical data to soil properties maps. For two test sites, located respectively in Luxembourg (LU) and Mugello (IT) a set of soil properties maps have been produced. They give information about the C content, water content, clays content and soil thickness, allowing to deal with the main threats to soils related to erosion, SOC decreasing, water management and soil erosion.

Grandjean, G.

2012-04-01

295

Bacterial community structure and soil properties of a subarctic tundra soil in Council, Alaska.  

PubMed

The subarctic region is highly responsive and vulnerable to climate change. Understanding the structure of subarctic soil microbial communities is essential for predicting the response of the subarctic soil environment to climate change. To determine the composition of the bacterial community and its relationship with soil properties, we investigated the bacterial community structure and properties of surface soil from the moist acidic tussock tundra in Council, Alaska. We collected 70 soil samples with 25-m intervals between sampling points from 0-10 cm to 10-20 cm depths. The bacterial community was analyzed by pyrosequencing of 16S rRNA genes, and the following soil properties were analyzed: soil moisture content (MC), pH, total carbon (TC), total nitrogen (TN), and inorganic nitrogen (NH4+ and NO3-). The community compositions of the two different depths showed that Alphaproteobacteria decreased with soil depth. Among the soil properties measured, soil pH was the most significant factor correlating with bacterial community in both upper and lower-layer soils. Bacterial community similarity based on jackknifed unweighted unifrac distance showed greater similarity across horizontal layers than through the vertical depth. This study showed that soil depth and pH were the most important soil properties determining bacterial community structure of the subarctic tundra soil in Council, Alaska. PMID:24893754

Kim, Hye Min; Jung, Ji Young; Yergeau, Etienne; Hwang, Chung Yeon; Hinzman, Larry; Nam, Sungjin; Hong, Soon Gyu; Kim, Ok-Sun; Chun, Jongsik; Lee, Yoo Kyung

2014-08-01

296

Determination of hydraulic properties in the vicinity of a landfill near Antioch, Illinois  

USGS Publications Warehouse

A hydrogeologic investigation was conducted in and around a landfill near Antioch, Illinois, in December 1987. The investigation consisted, in part, of an aquifer test that was designed to determine the hydraulic connection between the hydrogeologic units in the area. The hydrogeologic units consist of a shallow, unconfined, sand and gravel aquifer of variable thickness that overlies an intermediate confining unit of variable thickness composed predominantly of till. Underlying the till is a deep, confined, sand and gravel aquifer that serves as the water supply for the village of Antioch. The aquifer test was conducted in the confined aquifer. Aquifer-test data were analyzed using the Hantush and Jacob method for a leaky confined aquifer with no storage in the confining unit. Calculated transmissivity of the confined aquifer ranged from 1.96x10^4 to 2.52x10^4 foot squared per day and storativity ranged from 2.10x10^-4 to 8.71x10^-4. Leakage through the confining unit ranged from 1.29x10^-4 to 7.84x10^-4 foot per day per foot, and hydraulic conductivity of the confining unit ranged from 3.22x10^-3 to 1.96x10^-2 foot per day. The Hantush method for analysis of a leaky confined aquifer with storage in the confining unit also was used to estimate aquifer and confining-unit properties. Transmissivity and storativity values calculated using the Hantush method are in good agreement with the values calculated from the Hantush and Jacob method. Properties of the confining unit were estimated using the ratio method of Neuman and Witherspoon. The estimated diffusivity of the confining unit ranged from 50.36 to 68.13 feet squared per day, A value for the vertical hydraulic conductivity of the confining unit calculated from data obtained using both the Hantush and the Neuman and Witherspoon methods was within the range of values calculated by the Hantush and Jacob method. The aquifer-test data clearly showed that the confining unit is hydraulically connected to the confined aquifer. The aquifer-test data also indicated that the unconfined aquifer becomes hydraulically connected to the deep sand and gravel aquifer within 24 hours after the start of pumping in the confined aquifer.

Kay, Robert T.; Earle, John D.

1990-01-01

297

Modeling the heterogeneous hydraulic properties of faults using constraints from reservoir-induced seismicity  

NASA Astrophysics Data System (ADS)

This research uses observations of reservoir-induced seismicity beneath Açu Reservoir, NE Brazil, to investigate the spatial distribution of permeability within the damage zone surrounding faults. The Açu dam is a 34 m high earth-filled dam constructed in 1983 on an area of Precambrian shield. Our previous work has shown that fluctuations in seismic activity are related to varying reservoir level via the diffusion of pore pressure within high-permeability faults embedded in a lower-permeability matrix. High-resolution monitoring of the seismic activity within individual faults, using a network of three-component digital seismographs, has revealed a complex spatial pattern of earthquake clustering and migration that suggests heterogeneous fault zone hydraulic properties are present. We first review the laboratory and field evidence for variations in hydraulic properties associated with (1) structural architecture of faults and (2) confining pressure. We then model flow through a heterogeneous two-dimensional (2-D) fault embedded in, and explicitly coupled to, a 3-D medium and include a power law decay in diffusivity with depth associated with crack closure. Diffusivity of the fault is represented by a spatially correlated random field. We vary both the correlation length and variance of the diffusivity field and calculate the time lag between the maximum reservoir level and the maximum piezometric head in the depth range of observed seismic activity. By assuming that individual earthquake ruptures occur when the local piezometric head is at a maximum, we are able to infer the correlation length and variance that best explain the spatiotemporal pattern of the activity within each seismic cluster. The spatial and temporal evolution of seismicity within clusters is only found to be consistent with a causal mechanism of pore pressure diffusion when significant spatial structure is present in the heterogeneous fault hydraulic properties.

Do Nascimento, Aderson F.; Lunn, Rebecca J.; Cowie, Patience A.

2005-09-01

298

Photosynthetic, hydraulic and biomass properties in closely related C3 and C4 species.  

PubMed

In plants, most water is absorbed by roots and transported through vascular conduits of xylem which evaporate from leaves during photosynthesis. As photosynthesis and transport processes are interconnected, it was hypothesized that any variation in water transport demand influencing water use efficiency (WUE), such as the evolution of C4 photosynthesis, should affect xylem structure and function. Several studies have provided evidence for this hypothesis, but none has comprehensively compared photosynthetic, hydraulic and biomass allocation properties between C3 and C4 species. In this study, photosynthetic, hydraulic and biomass properties in a closely related C3 Tarenaya hassleriana and a C4 Cleome gynandra are compared. Light response curves, measured at 30°C, showed that the C4 C. gynandra had almost twice greater net assimilation rates than the C3 T. hassleriana under each increasing irradiation level. On the contrary, transpiration rates and stomatal conductance were around twice as high in the C3 , leading to approximately 3.5 times higher WUE in the C4 compared with the C3 species. The C3 showed about 3.3 times higher hydraulic conductivity, 4.3 times greater specific conductivity and 2.6 times higher leaf-specific conductivity than the C4 species. The C3 produced more vessels per xylem area and larger vessels. All of these differences resulted in different biomass properties, where the C4 produced more biomass in general and had less root to shoot ratio than the C3 species. These results are in support of our previous findings that WUE, and any changes that affect WUE, contribute to xylem evolution in plants. PMID:24930487

Kocacinar, Ferit

2015-03-01

299

Effect of a water-based drilling waste on receiving soil properties and plants growth.  

PubMed

This investigation was undertaken to determine the relative effects of recommended land spraying while drilling (LWD) loading rate application for a source of water-based drilling waste material on selected soil properties and phytotoxicity. Drilling waste material was obtained from a well where a nitrate gypsum water based product was used to formulate the drilling fluid. The fluid and associated drill cuttings were used as the drilling waste source to conduct the experiment. The study was carried out in triplicate and involved five plant species, four drilling waste loading rates and a representative agricultural soil type in Alberta. Plant growth was monitored for a period of ten days. Drilling waste applied at 10 times above the recommended loading rate improved the growth and germination rate of all plants excluding radish. Loading rates in excess of 40 and 50 times had a deleterious effect on radish, corn and oat but not on alfalfa and barley. Germination rate decreased as waste loading rate increased. Effects on soil physical and chemical properties were more pronounced at the 40 and 50 times exceeding recommended loading rate. Significant changes in soil parameters occurred at the higher rates in terms of increase in soil porosity, pH, EC, hydraulic conductivity, SAR and textural classification. This study indicates that the applications of this type of water based drill cutting if executed at an optimal loading rate, may improve soil quality and results in better plant growth. PMID:24117079

Saint-Fort, Roger; Ashtani, Sahar

2014-01-01

300

Effect of Fresh Poultry Litter and Compost on Soil Physical and Chemical Properties  

NASA Technical Reports Server (NTRS)

Application of poultry litter and compost as a substitute for fertilizer not only uses unwanted waste and decreases expenditures for commercial fertilizer, it adds nutrients to soil for plant uptake. The properties of soil affected by poultry litter were analyzed to determine the positive and negative aspects of using this substitute fertilizer. This study focused on changes associated with saturated hydraulic conductivity, bulk density, nitrate concentrations, and pH after application of varying concentrations of poultry litter and compost. Soil samples from Tennessee Valley Substation in Alabama were analyzed in a laboratory at Alabama A&M University. As a result of the application of fresh poultry litter and compost, we found that the saturated hydraulic conductivity increased and the bulk density decreased, while the pH was generally not affected. Using poultry litter and compost as an alternative commercial fertilizers could be adapted by the farming community to protect the sustainability of our environment. Unwanted waste is used productively and soil is enriched for farming.

Carr, Stacy; Tsegaye, Teferi; Coleman, Tommy

1998-01-01

301

Hydraulic properties of Hanford Waste Vitrification Project 39-4 frit slurries  

SciTech Connect

Pacific Northwest Laboratory (PNL) conducted this study for Fluor Daniel Inc. and Westinghouse Hanford Company. The purpose of the study was to assess the effect of solids loading on the hydraulic properties of frit slurries. The effect of solids loading on the hydraulic properties of the fret slurries was evaluated by testing various concentrations of frit slurries in various sized schedule 40 stainless steel piping. The pressure drop in straight and 90-degree long radius elbow sections was measured as a function of flowrate, pipe size, and solids concentration. The results of testing yielded recommendations for predicting the pressure drop as a function of solids concentration, pipe size, and flow-rate. The contribution of a 90-degree long radius elbow to the pressure drop was measured and recommendations given. Observations were also made on solids settling in the lines, wear on the testing equipment, slurry properties, and measuring equipment performance. The equipment and procedures used for pumping the high solids concentration frit slurry were successful in completing the test.

Abrigo, G.P.

1996-03-01

302

Photoinhibition of stem elongation by blue and red light: effects on hydraulic and cell wall properties  

NASA Technical Reports Server (NTRS)

The underlying mechanism of photoinhibition of stem elongation by blue (BL) and red light (RL) was studied in etiolated seedlings of pea (Pisum sativum L. cv Alaska). Brief BL irradiations resulted in fast transient inhibition of elongation, while a delayed (lag approximately 60 minutes) but prolonged inhibition was observed after brief RL. Possible changes in the hydraulic and wall properties of the growing cells during photoinhibition were examined. Cell sap osmotic pressure was unaffected by BL and RL, but both irradiations increased turgor pressure by approximately 0.05 megapascal (pressure-probe technique). Cell wall yielding was analyzed by in vivo stress relaxation (pressure-block technique). BL and RL reduced the initial rate of relaxation by 38 and 54%, while the final amount of relaxation was decreased by 48 and 10%, respectively. These results indicate that RL inhibits elongation mainly by lowering the wall yield coefficient, while most of the inhibitory effect of BL was due to an increase of the yield threshold. Mechanical extensibility of cell walls (Instron technique) was decreased by BL and RL, mainly due to a reduction in the plastic component of extensibility. Thus, photoinhibitions of elongation by both BL and RL are achieved through changes in cell wall properties, and are not due to effects on the hydraulic properties of the cell.

Kigel, J.; Cosgrove, D. J.

1991-01-01

303

The influence of shade and clouds on soil water potential: The buffered behavior of hydraulic lift  

Microsoft Academic Search

In the sagebrush\\/bunchgrass steppe of the North American Great Basin soil water potential has been shown to exhibit diel fluctuations with water potential increasing during the night as a result of water loss from roots in relatively dry soil layers. We hypothesized that environmental conditions promoting low transpiration rates (shading, cloudiness) would cause a net increase in soil water potential

Kimberlyn Williams; Martyn M. Caldwell; James H. Richards

1993-01-01

304

First look at rock & soil properties  

NASA Technical Reports Server (NTRS)

The earliest survey of spectral properties of the rocks and soils surrounding Pathfinder was acquired as a narrow strip covering the region just beyond the where the rover made its egress from the lander. The wavelength filters used, all in the binocular camera's right eye, cover mainly visible wavelengths. These data reveal at least five kinds of rocks and soil in the immediate vicinity of the lander. All of the spectra are ratioed to the mean spectrum of bright red drift to highlight the differences. Different occurrences of drift (pink spectra) are closely similar. Most of the rocks (black spectra) have a dark gray color, and are both darker and less red than the drift, suggesting less weathering. Typical soils (green spectra) are intermediate in properties to the rocks and drift. Both these data and subsequent higher resolution images show that the typical soil consists of a mixture of drift and small dark gray particles resembling the rock. However, two other kinds of materials are significantly different from the rocks and drift. Pinkish or whitish pebbles and crusts on some of the rocks (blue spectra) are brighter in blue light and darker in near-infrared light than is the drift, and they lack the spectral characteristics closely associated with iron minerals. Dark red soils in the lee of several rocks are about as red as the drift, but consistently darker. The curvature in the spectrum at visible wavelengths suggests either more ferric iron minerals than in the drift or a larger particle size.

Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator. JPL is an operating division of the California Institute of Technology (Caltech).

1997-01-01

305

Effect of parameter choice in root water uptake models - the arrangement of root hydraulic properties within the root architecture affects dynamics and efficiency of root water uptake  

NASA Astrophysics Data System (ADS)

Detailed three-dimensional models of root water uptake have become increasingly popular for investigating the process of root water uptake. However, they suffer from a lack of information on important parameters, particularly on the spatial distribution of root axial and radial conductivities, which vary greatly along a root system. In this paper we explore how the arrangement of those root hydraulic properties and branching within the root system affects modelled uptake dynamics, xylem water potential and the efficiency of root water uptake. We first apply a simple model to illustrate the mechanisms at the scale of single roots. By using two efficiency indices based on (i) the collar xylem potential ("effort") and (ii) the integral amount of unstressed root water uptake ("water yield"), we show that an optimal root length emerges, depending on the ratio between roots axial and radial conductivity. Young roots with high capacity for radial uptake are only efficient when they are short. Branching, in combination with mature transport roots, enables soil exploration and substantially increases active young root length at low collar potentials. Second, we investigate how this shapes uptake dynamics at the plant scale using a comprehensive three-dimensional root water uptake model. Plant-scale dynamics, such as the average uptake depth of entire root systems, were only minimally influenced by the hydraulic parameterization. However, other factors such as hydraulic redistribution, collar potential, internal redistribution patterns and instantaneous uptake depth depended strongly on the arrangement on the arrangement of root hydraulic properties. Root systems were most efficient when assembled of different root types, allowing for separation of root function in uptake (numerous short apical young roots) and transport (longer mature roots). Modelling results became similar when this heterogeneity was accounted for to some degree (i.e. if the root systems contained between 40 and 80% of young uptake roots). The average collar potential was cut to half and unstressed transpiration increased by up to 25% in composed root systems, compared to homogenous ones. Also, the least efficient root system (homogenous young root system) was characterized by excessive bleeding (hydraulic lift), which seemed to be an artifact of the parameterization. We conclude that heterogeneity of root hydraulic properties is a critical component for efficient root systems that needs to be accounted for in complex three-dimensional root water uptake models.

Bechmann, M.; Schneider, C.; Carminati, A.; Vetterlein, D.; Attinger, S.; Hildebrandt, A.

2014-10-01

306

Structural transition in the humic matrix of soil gels and its effect on the soil properties  

NASA Astrophysics Data System (ADS)

The analysis of drying-wetting cycles in soils has shown that the existence of the humic matrix of soil gels and, hence, the soil structure is ensured by hydrophilic bonds in dry soils and hydrophobic bonds in wet soils. This suggests that the structural transition from one mechanism controlling the stability of the soil gels and the existence of the soil structure to another mechanism occurs in the humic matrix of soil gels in a specific range of water content. The experimental results have confirmed the effect of the structural transition on the water stability of the soil structure, the pHwater, the hydrophilicity of the soil particle surface, and the structural-mechanical properties of the soils.

Fedotov, G. N.; Shoba, S. A.; Pozdnyakov, A. I.; Puzanova, A. E.

2014-09-01

307

A Hydraulic Model Is Compatible with Rapid Changes in Leaf Elongation under Fluctuating Evaporative Demand and Soil Water Status1[C][W][OPEN  

PubMed Central

Plants are constantly facing rapid changes in evaporative demand and soil water content, which affect their water status and growth. In apparent contradiction to a hydraulic hypothesis, leaf elongation rate (LER) declined in the morning and recovered upon soil rehydration considerably quicker than transpiration rate and leaf water potential (typical half-times of 30 min versus 1–2 h). The morning decline of LER began at very low light and transpiration and closely followed the stomatal opening of leaves receiving direct light, which represent a small fraction of leaf area. A simulation model in maize (Zea mays) suggests that these findings are still compatible with a hydraulic hypothesis. The small water flux linked to stomatal aperture would be sufficient to decrease water potentials of the xylem and growing tissues, thereby causing a rapid decline of simulated LER, while the simulated water potential of mature tissues declines more slowly due to a high hydraulic capacitance. The model also captured growth patterns in the evening or upon soil rehydration. Changes in plant hydraulic conductance partly counteracted those of transpiration. Root hydraulic conductivity increased continuously in the morning, consistent with the transcript abundance of Zea maize Plasma Membrane Intrinsic Protein aquaporins. Transgenic lines underproducing abscisic acid, with lower hydraulic conductivity and higher stomatal conductance, had a LER declining more rapidly than wild-type plants. Whole-genome transcriptome and phosphoproteome analyses suggested that the hydraulic processes proposed here might be associated with other rapidly occurring mechanisms. Overall, the mechanisms and model presented here may be an essential component of drought tolerance in naturally fluctuating evaporative demand and soil moisture. PMID:24420931

Caldeira, Cecilio F.; Bosio, Mickael; Parent, Boris; Jeanguenin, Linda; Chaumont, François; Tardieu, François

2014-01-01

308

ADVANCED FIELD AND LABORATORY METHODS IN SOIL SCIENCE  

E-print Network

physical properties and states · Measure fundamental soil chemical properties · Measure fundamental soil for later analysis. Each week, laboratory measurements will be made (or initiated) or additional field: Hydraulic conductivity, infiltration Novak Novak Apr 8 Apr 9 Lab: Field hydraulic conductivity (auger hole

Farrell, Anthony P.

309

The effect of electrolyte composition on hydraulic conductivity of some Texas soils  

E-print Network

(8, 1 , 24, 25, 2n). Related work togeth r vith the appropriate acreages, are included in the Appendix A. Hydraulic conductivity mea urencents were mace in soecially de- signen permesmeters with two ounce! trit. r:nes as desc ribed by Hc...

Naghshineh-Pour, Bijan

2012-06-07

310

Leaf hydraulics I: scaling transport properties from single cells to tissues.  

PubMed

In leaf tissues, water may move through the symplast or apoplast as a liquid, or through the airspace as vapor, but the dominant path remains in dispute. This is due, in part, to a lack of models that describe these three pathways in terms of experimental variables. We show that, in plant water relations theory, the use of a hydraulic capacity in a manner analogous to a thermal capacity, though it ignores mechanical interactions between cells, is consistent with a special case of the more general continuum mechanical theory of linear poroelasticity. The resulting heat equation form affords a great deal of analytical simplicity at a minimal cost: we estimate an expected error of less than 12%, compared to the full set of equations governing linear poroelastic behavior. We next consider the case for local equilibrium between protoplasts, their cell walls, and adjacent air spaces during isothermal hydration transients to determine how accurately simple volume averaging of material properties (a 'composite' model) describes the hydraulic properties of leaf tissue. Based on typical hydraulic parameters for individual cells, we find that a composite description for tissues composed of thin walled cells with air spaces of similar size to the cells, as in photosynthetic tissues, is a reasonable preliminary assumption. We also expect isothermal transport in such cells to be dominated by the aquaporin-mediated cell-to-cell path. In the non-isothermal case, information on the magnitude of the thermal gradients is required to assess the dominant phase of water transport, liquid or vapor. PMID:24112968

Rockwell, Fulton E; Michele Holbrook, N; Stroock, Abraham D

2014-01-01

311

Relationships between induced polarization relaxation time and hydraulic properties of sandstone  

NASA Astrophysics Data System (ADS)

We investigated electrical and physical-chemical properties of six sandstone samples with contrasting mineralogical characteristics and with hydraulic conductivity varying in a wide range. The electrical data were obtained from time domain spectral induced polarization (IP) measurements. We inverted the IP decays to relaxation time distributions, and then compared the modal relaxation times with the dominant pore throat diameters obtained from the Mercury Injection Capillary Pressure (MICP) data. We found a positive logarithmic relationship between the relaxation time and the pore throat diameter. Also, we found the normalized chargeability (an integral IP parameter) to be positively correlated with the clay content. These two results suggest that the polarization of our sandstones is controlled by the pore throat distribution, and by the clay content. The logarithmic relationship contradicts previous theories, and is not universal. Adopting an approach of Kruschwitz and her co-workers, we calculated the effective diffusivity from IP and MICP data, and we found the effective diffusivity values ranging from 2.9 × 10-13 to 1.6 × 10-10 m2s-1. High diffusivity values, typical of surface diffusion, were obtained for clean sandstones. Low diffusivity values were obtained for clayey sandstones, and they were one to two orders of magnitude lower than those characteristic of the surface diffusion. We proposed two mechanisms to explain the `slow' diffusion: (1) the effect of surface tortuosity of pore throats filled with clay minerals and (2) the effect of pore geometry. These two effects represent an obstacle in assessing the pore throat diameter and hydraulic conductivity of sandstones with large specific surface and clay content on the basis of spectral IP measurements. However, we believe that the sandstones featuring `slow' diffusion can be discriminated based on the integral polarization parameters, and that the relaxation time remains a valuable parameter for assessing hydraulic properties of clean sandstones.

Titov, Konstantin; Tarasov, Andrey; Ilyin, Yuri; Seleznev, Nikita; Boyd, Austin

2010-03-01

312

Hydraulic properties of the Madison aquifer system in the western Rapid City area, South Dakota  

USGS Publications Warehouse

Available information on hydrogeology, data from borehole geophysical logs, and aquifer tests were used to determine the hydraulic properties of the Madison aquifer. From aquifer-test analysis, transmissivity and storage coefficient were determined for the Minnelusa and Madison aquifers, and vertical hydraulic conductivity (Kv') along with specific storage (Ss') for the Minnelusa confining bed. Borehole geophysical well logs were used to determine the thickness and location of the Minnelusa aquifer, the lower Minnelusa confining bed, and the Madison aquifer within the Madison Limestone. Porosity values determined from quantitative analysis of borehole geophysical well logs were used in analyzing the aquifer-test data. The average porosity at the two aquifer-test sites is about 10 percent in the Minnelusa aquifer, 5 percent in the lower Minnelusa confining bed, and 35 percent in the Madison aquifer. The first aquifer test, which was conducted at Rapid City production well #6, produced measured drawdown in the Minnelusa and Madison aquifers. Neuman and Witherspoon's method of determining the hydraulic properties of leaky two-aquifer systems was used to evaluate the aquifer-test data by assuming the fracture and solution-opening network is equivalent to a porous media. Analysis of the aquifer test for the Minnelusa aquifer yielded a transmissivity value of 12,000 feet squared per day and a storage coefficient of 3 x 10-3. The specific storage of the Minnelusa confining bed was 2 x 10-7 per foot, and its vertical hydraulic conductivity was 0.3 foot per day. The transmissivity of the Madison aquifer at this site was 17,000 feet squared per day, and the storage coefficient was 2 x 10-3. The second aquifer test, which was conducted at Rapid City production well #5 (RC-5) produced measured drawdown only in the Madison aquifer. Hantush and Jacob's method of determining the hydraulic properties of leaky confined aquifers with no storage in the confining bed was used to evaluate the aquifer-test data by assuming the fracture and solution-opening network is equivalent to a porous media. The analysis of data from the RC-5 aquifer test showed that transmissivity was not equal in all directions. Hantush's method was used to determine the direction of radial anisotropy and magnitude of the major and minor axes of transmissivity. The major axis of transmissivity is at an angle of 42? east of north, and the transmissivity along this axis is about 56,000 feet squared per day. The minor axis of transmissivity is at an angle of 48? west of north, and the transmissivity along this axis is about 1,300 feet squared per day. The major axis of transmissivity intersects Cleghorn Springs, a large resurgent spring on the west edge of Rapid City. The shape of the potentiometric contours of the Madison aquifer near RC-5 agree with the orientation of the transmissivity ellipse. The average value of the storage coefficient from the isotropic analysis of the aquifer-test data was 3.5 x 10-4, and the average vertical hydraulic conductivity of the lower Minnelusa confining bed was 9.6 x 10-3 foot per day.

Greene, Earl A.

1993-01-01

313

Estimating the hydraulic properties of an aquitard from in situ pore pressure measurements  

NASA Astrophysics Data System (ADS)

A workflow is described to estimate specific storage ( S s) and hydraulic conductivity ( K) from a profile of vibrating wire piezometers embedded into a regional aquitard in Australia. The loading efficiency, compressibility and S s were estimated from pore pressure response to atmospheric pressure changes, and K was estimated from the earliest part of the measurement record following grouting. Results indicate that S s and K were, respectively, 8.8 × 10-6 to 1.2 × 10-5 m-1 and 2 × 10-12 m s-1 for a claystone/siltstone, and 4.3 × 10-6 to 9.6 × 10-6 m-1 and 1 × 10-12 to 5 × 10-12 m s-1 for a thick mudstone. K estimates from the pore pressure response are within one order of magnitude when compared to direct measurement in a laboratory and inverse modelled flux rates determined from natural tracer profiles. Further analysis of the evolution and longevity of the properties of borehole grout (e.g. thermal and chemical effects) may help refine the estimation of formation hydraulic properties using this workflow. However, the convergence of K values illustrates the benefit of multiple lines of evidence to support aquitard characterization. An additional benefit of in situ pore pressure measurement is the generation of long-term data to constrain groundwater flow models, which provides a link between laboratory scale data and the formation scale.

Smerdon, Brian D.; Smith, Laura A.; Harrington, Glenn A.; Gardner, W. Payton; Piane, Claudio Delle; Sarout, Joel

2014-12-01

314

The influence of shade and clouds on soil water potential: The buffered behavior of hydraulic lift  

Microsoft Academic Search

In the sagebrush\\/bunchgrass steppe of the North American Great Basin soil water potential has been shown to exhibit diel fluctuations\\u000a with water potential increasing during the night as a result of water loss from roots in relatively dry soil layers. We hypothesized\\u000a that environmental conditions promoting low transpiration rates (shading, cloudiness) would cause a net increase in soil water\\u000a potential

Kimberlyn Williams; Martyn M. Caldwell; James H. Richards

1993-01-01

315

Palaeo?adaptive Properties of the Xylem of Metasequoia: Mechanical/Hydraulic Compromises  

PubMed Central

The xylem of Metasequoia glyptostroboides Hu et Cheng is characterized by very low density (average specific gravity = 0·27) and tracheids with relatively large dimensions (length and diameter). The microfibril angle in the S2 layer of tracheid walls is large, even in outer rings, suggesting a cambial response to compressive rather than tensile stresses. In some cases, this compressive stress is converted to irreversible strain (plastic deformation), as evidenced by cell wall corrugations. The heartwood is moderately decay resistant, helping to prevent Brazier buckling. These xylem properties are referenced to the measured bending properties of modulus of rupture and modulus of elasticity, and compared with other low?to?moderate density conifers. The design strategy for Metasequoia is to produce a mechanically weak but hydraulically efficient xylem that permits rapid height growth and crown development to capture and dominate a wet site environment. The adaptability of these features to a high?latitude Eocene palaeoenvironment is discussed. PMID:12763758

JAGELS, RICHARD; VISSCHER, GEORGE E.; LUCAS, JOHN; GOODELL, BARRY

2003-01-01

316

A Long-Term Strategic Plan for Hanford Sediment Physical Property and Vadose Zone Hydraulic Parameter Databases  

SciTech Connect

Physical property data and unsaturated hydraulic parameters are critical input for analytic and numerical models used to predict transport and fate of contaminants in variably saturated porous media and to assess and execute remediation alternatives. The Remediation Decision Support (RDS) project, managed by the Pacific Northwest National Laboratory (PNNL) for the U.S. Department of Energy (DOE) and the CH2M Hill Plateau Remediation Company (CHPRC), has been compiling physical and hydraulic property data and parameters to support risk analyses and waste management decisions at Hanford. Efforts have been initiated to transfer sediment physical property data and vadose zone hydraulic parameters to CHPRC for inclusion in HEIS-Geo, a new instance of the Hanford Environmental Information System database that is being developed for borehole geologic data. This report describes these efforts and a strategic plan for continued updating and improvement of these datasets.

Rockhold, Mark L.; Last, George V.; Middleton, Lisa A.

2009-09-30

317

Flow Rate Dependence of Soil Hydraulic Characteristics D. Wildenschild,* J. W. Hopmans, J. Simunek  

E-print Network

ofgiven matric potential, more water was retained with greater applied the retention characteristic increasing total water potential gradient in the sandy air volume entrapped during absorption if the soil the soil water matric ling flow in unsaturated porous media are the reten- potential and the water content

Wildenschild, Dorthe

318

Threshold response of mesophyll CO2 conductance to leaf hydraulics in highly transpiring hybrid poplar clones exposed to soil drying  

PubMed Central

Mesophyll conductance (g m) has been shown to impose significant limitations to net CO2 assimilation (A) in various species during water stress. Net CO2 assimilation is also limited by stomatal conductance to water (g sw), both having been shown to co-vary with leaf hydraulic conductance (K leaf). Lately, several studies have suggested a close functional link between K leaf, g sw, and g m. However, such relationships could only be circumstantial since a recent study has shown that the response of g m to drought could merely be an artefactual consequence of a reduced intercellular CO2 mole fraction (C i). Experiments were conducted on 8-week-old hybrid poplar cuttings to determine the relationship between K leaf, g sw, and g m in clones of contrasting drought tolerance. It was hypothesized that changes in g sw and K leaf in response to drought would not impact on g m over most of its range. The results show that K leaf decreased in concert with g sw as drought proceeded, whereas g m measured at a normalized C i remained relatively constant up to a g sw threshold of ~0.15mol m–2 s–1. This delayed g m response prevented a substantial decline in A at the early stage of the drought, thereby enhancing water use efficiency. Reducing the stomatal limitation of droughted plants by diminishing the ambient CO2 concentration of the air did not modify g m or K leaf. The relationship between gas exchange and leaf hydraulics was similar in both drought-tolerant and drought-sensitive clones despite their contrasting vulnerability to stem cavitation and stomatal response to soil drying. The results support the hypothesis of a partial hydraulic isolation of the mesophyll from the main transpiration pathway. PMID:24368507

Pepin, Steeve

2014-01-01

319

Greywater reuse for irrigation: effect on soil properties.  

PubMed

A controlled study of the effect of greywater (GW) irrigation on soil properties was conducted. Containers of sand, loam and loess soils were planted with lettuce, and irrigated with fresh water, raw artificial GW or treated artificial GW. Greywater was treated using a recirculating vertical-flow constructed wetland. Soil samples were collected every 10 days for the 40-day duration of the study, and plant growth was measured. Soils were analysed for physicochemical and biological parameters to determine changes caused by the different treatments. It was demonstrated that raw artificial GW significantly increased the development of hydrophobicity in the sand and loam soils, as determined by water droplet penetration time. No significant changes were observed for the loess soil under all treatments. Observed hydrophobicity was correlated with increased oil and grease and surfactant concentrations in the soil. Zeta (zeta) potential of the soils was measured to determine changes in the soil particle surface properties as a result of GW irrigation. A significant change in zeta-potential (less negative) was observed in the raw artificial GW-irrigated sand, whereas no difference was observed in the loam or loess. Soils irrigated with fresh water or treated GW exhibited no increase in hydrophobicity. Fecal coliform bacteria were absent or <10 CFU g(-1) in soils irrigated with fresh water or treated GW, but at least 1 order of magnitude higher in raw artificial GW irrigated soils. Only in the last sampling event and only for the loess soil was plant growth significantly higher for fresh water irrigated vs. raw or treated GW irrigated soils. This study demonstrates that treated GW can be effectively irrigated without detrimental effects on soil or plant growth; however, raw GW may significantly change soil properties that can impact the movement of water in soil and the transport of contaminants in the vadose zone. PMID:20350744

Travis, Micheal J; Wiel-Shafran, Alit; Weisbrod, Noam; Adar, Eilon; Gross, Amit

2010-05-15

320

Decoupling the influence of leaf and root hydraulic conductances on stomatal conductance and its sensitivity to vapour pressure deficit as soil dries in a drained loblolly pine plantation  

Microsoft Academic Search

The study examined the relationships between whole tree hydraulic conductance (Ktree) and the conductance in roots (Kroot) and leaves (Kleaf) in loblolly pine trees. In addition, the role of seasonal variations in Kroot and Kleaf in mediating stomatal control of transpiration and its response to vapour pressure deficit (D) as soil-dried was studied. Compared to trunk and branches, roots and

JEAN-CHRISTOPHE DOMEC; ASKO NOORMETS; JOHN S. KING; GE SUN; STEVEN G. MCNULTY; MICHAEL J. GAVAZZI; JOHNNY L. BOGGS; EMRYS A. TREASURE

2009-01-01

321

EFFECTS OF COMPOST AND LIME APPLICATION ON SOIL CHEMICAL PROPERTIES, SOIL MICROBIAL COMMUNITY, AND FUSARIUM WILT IN  

E-print Network

1 EFFECTS OF COMPOST AND LIME APPLICATION ON SOIL CHEMICAL PROPERTIES, SOIL MICROBIAL COMMUNITY compost as an antagonistic suppression approach to combat soil-borne disease effects on crop yields the effect of compost and lime on soil chemical properties, the soil microbial community (including Fusarium

Ma, Lena

322

Effect of High Cooling Rates on the Mineralogy and Hydraulic Properties of Stainless Steel Slags  

NASA Astrophysics Data System (ADS)

This article investigates the effect of chemical composition and cooling rate during solidification on the mineralogy and hydraulic properties of synthetic stainless steel slags. Three synthetic slags, covering the range of typical chemical composition in industrial practice, were subjected to high cooling rates, by melt spinning granulation or quenching in water, and to low cooling rates, by cooling inside the furnace. Both methods of rapid cooling led to volumetrically stable slags unlike the slow cooling which resulted in a powder-like material. Stabilized slags consisted predominantly of lamellar ?-dicalcium silicate ( ?-C2S) and Mg, Ca-silicates (merwinite and bredigite); the latter form the matrix at low basicity and are segregated along the C2S grain boundaries at high basicities. Slowly cooled slags consist of the ?-C2S polymorph instead of the ?-C2S and of less Mg, Ca-silicates. Isothermal conduction calorimetry and thermogravimetric analysis indicate the occurrence of hydration reactions in the stabilized slags after mixing with water, while calcium silicate hydrates (C-S-H) of typical acicular morphology are identified by SEM. The present results demonstrate that the application of high cooling rates can result in a stable, environmental-friendly, hydraulic binder from stainless steel slags, rich in ?-C2S, without the necessity of introducing any additions to arrest the ? polymorph.

Kriskova, Lubica; Pontikes, Yiannis; Pandelaers, Lieven; Cizer, Özlem; Jones, Peter Tom; Van Balen, Koen; Blanpain, Bart

2013-10-01

323

Hydraulic properties and scale effects investigation in regional rock aquifers, south-western Quebec, Canada  

NASA Astrophysics Data System (ADS)

This paper reports on the characterization of hydraulic properties of regional rock aquifers carried out within a groundwater resources assessment project in the St. Lawrence Lowlands of south-western Quebec. To understand the aquifer behavior at both the fracture level and at field scale, hydraulic investigations were carried out using various aquifer tests. The groundwater flow at the local scale is controlled mostly by the fracture system. Results of the constant-head injection tests show a weak decreasing trend of hydraulic conductivity with depth indicating that a major part of the groundwater flow occurs in the first meters of the rock sequence. At the regional scale, the equivalent porous media approach is applicable. The hydraulic conductivity measurements were correlated to the scale of the aquifer tests expressed with the investigated aquifer volume. A simple interpolation procedure for the hydraulic conductivity field was developed based on the distance between field measurements and the tested aquifer volumes. The regional distribution of the hydraulic conductivity for the major fractured aquifer units indicates that dolostone is the most permeable whereas sandstone and crystalline rocks are the least permeable units. Este artículo trata de la caracterización de las propiedades hidráulicas en acuíferos regionales rocosos, la cual se llevó a cabo dentro del proyecto de evaluación de los recursos de agua subterránea en St. Lawrence Lowlands al suroeste de Quebec. Para entender el comportamiento del acuífero tanto a nivel de fractura como a escala del campo, se ejecutaron investigaciones hidráulicas usando varias pruebas de acuífero. El flujo del agua subterránea a escala local está controlado principalmente por el sistema de fracturas. Los resultados de las pruebas de inyección con cabeza constante muestran una tendencia decreciente débil de la conductividad hidráulica con la profundidad, indicando que la mayor parte del flujo de agua subterránea sucede en los primeros metros de la secuencia rocosa. A escala regional se puede aplicar la aproximación equivalente de medios porosos. Las medidas de la conductividad hidrálica fueron comparadas con la escala de las pruebas del acuífero, expresadas con el volumen investigado del acuífero. Se desarrolló un proceso de interpolación simple para la conductividad hidráulica de campo, con base en la distancia entre las medidas de campo y los volúmenes probados del acuífero. La distribución regional de la conductividad hidráulica, para las unidades acuíferas fracturadas mayores, indica que la dolomita es más permeable mientras que la arenisca y las rocas cristalinas son las unidades menos permeables. L'article présente les propriétés hydrauliques d'un aquifère régional rocheux qui ont été mesurées dans le cadre d'un projet concernant l'estimation de la ressource en eau de la plaine de St. Lawrence située dans la partie sud-ouest de Quebec. Affin de comprendre le comportement de l'aquifère tant à l'échelle de fracture qu'à l'échelle régionale on a mené des investigations hydrauliques en utilisant des essais differents. À l'échelle locale l'écoulement est déterminé en principal par le système des fractures. Les résultats des essais d'injection au niveau constant ont montré une tendence de décroissance de la conductivité hydraulique avec la profondeur ce qui indique que l'écoulement ait lieu en principal dans les premiers mètres de la structure rocheuse. À l'échelle règionale on peut appliquer l'approche de milieux poreux equivalent. Les mesures de conductivité hydraulique ont été corrélées avec l'échelle des essais de pompage exprimée en termes de volume investigué de l'aquifère. On a mis au point une méthode simple d'interpolation pour le champ de la conductivité hydraulique basée sur la distance entre les essais in situ et les volume investigués de l'aquifère. La distribution règionale de la conductivité hydraulique montre que pour la majorité des unités de roche fracturé les plus perméable sont

Nastev, M.; Savard, M. M.; Lapcevic, P.; Lefebvre, R.; Martel, R.

324

Aquifer test to determine hydraulic properties of the Elm aquifer near Aberdeen, South Dakota  

USGS Publications Warehouse

The Elm aquifer, which consists of sandy and gravelly glacial-outwash deposits, is present in several counties in northeastern South Dakota. An aquifer test was conducted northeast of Aberdeen during the fall of 1999 to determine the hydraulic properties of the Elm aquifer in that area. An improved understanding of the properties of the aquifer will be useful in the possible development of the aquifer as a water resource. Historical water-level data indicate that the saturated thickness of the Elm aquifer can change considerably over time. From September 1977 through November 1985, water levels at three wells completed in the Elm aquifer near the aquifer test site varied by 5.1 ft, 9.50 ft, and 11.1 ft. From June 1982 through October 1999, water levels at five wells completed in the Elm aquifer near the aquifer test site varied by 8.7 ft, 11.4 ft, 13.2 ft, 13.8 ft, and 19.7 ft. The water levels during the fall of 1999 were among the highest on record, so the aquifer test was affected by portions of the aquifer being saturated that might not be saturated during drier times. The aquifer test was conducted using five existing wells that had been installed prior to this study. Well A, the pumped well, has an operating irrigation pump and is centrally located among the wells. Wells B, C, D, and E are about 70 ft, 1,390 ft, 2,200 ft, and 3,100 ft, respectively, in different directions from Well A. Using vented pressure transducers and programmable data loggers, water-level data were collected at the five wells prior to, during, and after the pumping, which started on November 19, 1999, and continued a little over 72 hours. Based on available drilling logs, the Elm aquifer near the test area was assumed to be unconfined. The Neuman (1974) method theoretical response curves that most closely match the observed water-level changes at Wells A and B were calculated using software (AQTESOLV for Windows Version 2.13-Professional) developed by Glenn M. Duffield of HydroSOLVE, Inc. These best fit theoretical response curves are based on a transmissivity of 24,000 ft2/d or a hydraulic conductivity of about 600 ft/d, a storage coefficient of 0.05, a specific yield of 0.42, and vertical hydraulic conductivity equal to horizontal hydraulic conductivity. The theoretical type curves match the observed data fairly closely at Wells A and B until about 2,500 minutes and 1,000 minutes, respectively, after pumping began. The increasing rate of drawdown after these breaks is an indication that a no-flow boundary (an area with much lower hydraulic conductivity) likely was encountered and that Wells A and B may be completed in a part of the Elm aquifer with limited hydraulic connection to the rest of the aquifer. Additional analysis indicates that if different assumptions regarding the screened interval for Well B and aquifer anisotropy are used, type curves can be calculated that fit the observed data using a lower specific yield that is within the commonly accepted range. When the screened interval for Well B was reduced to 5 ft near the top of the aquifer and horizontal hydraulic conductivity was set to 20 times vertical hydraulic conductivity, the type curves calculated using a specific yield of 0.1 and a transmissivity of 30,200 ft2/d also matched the observed data from Wells A and B fairly well. A version of the Theim equilibrium equation was used to calculate the theoretical drawdown in an idealized unconfined aquifer when a perfectly efficient well is being pumped at a constant rate. These calculations were performed for a range of pumping rates, drawdowns at the wells, and distances between wells that might be found in a production well field in the Elm aquifer. Although the aquifer test indicates that hydraulic conductivity near the well may be adequate to support a production well, the comparison of drawdown and recovery curves indicates the possibility that heterogeneities may limit the productive capacity of specific loca

Schaap, Bryan D.

2000-01-01

325

Soil Properties Controlling Zn Speciation and Fractionation in Contaminated Soils  

SciTech Connect

We determined the speciation of Zn in 49 field soils differing widely in pH (4.1-7.7) and total Zn content (251-30,090 mg/kg) by using extended X-ray absorption fine structure (EXAFS) spectroscopy. All soils had been contaminated since several decades by inputs of aqueous Zn with runoff-water from galvanized power line towers. Pedogenic Zn species identified by EXAFS spectroscopy included Zn in hydroxy-interlayered minerals (Zn-HIM), Zn-rich phyllosilicates, Zn-layered double hydroxide (Zn-LDH), hydrozincite, and octahedrally and tetrahedrally coordinated sorbed or complexed Zn. Zn-HIM was only observed in (mostly acidic) soils containing less than 2000 mg/kg of Zn, reflecting the high affinity but limited sorption capacity of HIM. Zn-bearing precipitates, such as Zn-LDH and Zn-rich trioctahedral phyllosilicates, became more dominant with increasing pH and increasing total Zn content relative to available adsorption sites. Zn-LDH was the most abundant Zn-precipitate and was detected in soils with pH > 5.2. Zn-rich phyllosilicates were detected even at lower soil pH, but were generally less abundant than Zn-LDH. Hydrozincite was only identified in two calcareous soils with extremely high Zn contents. In addition to Zn-LDH, large amounts of Zn in highly contaminated soils were mainly accumulated as sorbed/complexed Zn in tetrahedral coordination. Soils grouped according to their Zn speciation inferred from EXAFS spectroscopy mainly differed with respect to soil pH and total Zn content. Clear differences were observed with respect to Zn fractionation by sequential extraction: From Zn-HIM containing soils, most of the total Zn was recovered in the exchangeable and the most recalcitrant fractions. In contrast, from soils containing the highest percentage of Zn-precipitates, Zn was mainly extracted in intermediate extraction steps. The results of this study demonstrate that soil pH and Zn contamination level relative to available adsorption sites are the most important factors controlling the formation of pedogenic Zn-species in aerobic soils and, consequently, Zn fractionation by sequential extraction.

Jacquat, O.; Voegelin, A; Kretzschmar, R

2009-01-01

326

Hydrological properties of natural and reconstituted soils: compared methods.  

NASA Astrophysics Data System (ADS)

Among the physical parameters of soil, the hydrological properties fulfil an important role in illustrating its quality. The trend of the water retention curve indicates the condition of the soil and allows us to define, together with chemical parameters, its eventual state of decline. This work aims to describe the hydrological properties of different types of soils using various techniques and to compare the results. The soils examined can be subdivided into two types: natural soils and reconstituted soils obtained by a chemical mechanical treatment (patented by m.c.m. Ecosistemi s.r.l.) where an initial disgregation is followed by a reconstitution incorporating soil improvers,by a further polycondensation with humic acids and a final restoration. This study is part of a LIFE+ project, co-financed by the European Union and is entitled "Environmental recovery of degraded soils and desertified by a new treatment technology for land reconstruction" (Life 10 ENV IT 400 "New Life"). It aims to test the effectiveness of the reconstitution treatment of the soils in combatting their decline. Natural soils, on which this work is concentrated, are extreme soils: sandy soil (86.2% sand), silt loam soil (42.5% sand, 49.9% silt), clayey soil (54.6% clay, 38.5% silt); reconstituted soils were produced from these. Samples were taken to carry out analyses on water retention through the use of Richards pressure plates. Other samples were used to determine the saturation point and to carry out trials in pots in order to determine the moisture at the permanent wilting point. The information obtained from these laboratory tests were compared to the results of soil pedofunctions. Keywords: Reconstructed soils, Water retention, Permanent wilting point

Manfredi, Paolo; Cassinari, Chiara; Giupponi, Luca; Trevisan, Marco

2014-05-01

327

Hydraulic properties and inner structure of a relict rock glacier in the Eastern Alps, Austria  

NASA Astrophysics Data System (ADS)

Water economic studies in 1990s documented the importance of the springs draining relict rock glaciers for water supply and human consumption as well as for the ecosystem in alpine catchments in the Niederen Tauern Range, Austria. Recent studies confirm the hydrologic importance and show that in the easternmost subunit, the Seckauer Tauern Range, more than 40% of the area above 2000 m a.s.l. and up to 20% of the area above 1500 m a.s.l. drain through relict rock glaciers. Thus, the hydraulic properties of these alpine aquifers are considered to be important controls on the hydrology of these areas. Nevertheless their hydraulic properties and their inner structure are still poorly understood. Our hydrogeological research is carried out at the Schöneben Rock Glacier, located in Seckauer Tauern Range, Austria. This rock glacier is presumably relict although patches of permafrost might exist particularly in the upper part of the landform. The rock glacier covers an area of 0.11 km² and drains a total catchment of 0.76 km² with a maximum elevation of 2282 m a.s.l.. The rock glacier consists predominantly of gneissic sediments (mainly coarse-grained, blocky at the surface) and extends from 1720 to 1905 m a.s.l.. Discharge of the rock glacier spring is recorded since 2002. Electrical conductivity and water temperature used as natural tracers are continuously monitored since 2008. Furthermore, a tracer test with simultaneous injection of the fluorescent dyes naphthionate and fluoresceine at two injection points (one close to the front and one close to the rooting zone of the rock glacier) was performed. Recession analysis of the spring hydrograph reveals similarities to the flow dynamics of karst springs. The results exhibit on the one hand a slow base flow recession indicating a high storage capacity and on the other hand sharp discharge peaks immediately after rainfall events referring to a high hydraulic conductivity. Applying different analytic runoff models, the hydrograph analysis provides two possible conceptual aquifer models: (1) an aquifer with multiple overlapping exponential runoff components and (2) a single homogeneous aquifer with a runoff following a power law function triggered by diverging recharge pulse durations. Best fits to the analysed hydrographs were achieved with a 25 days recharge pulse and a base flow coefficient of 0.002 1/d. The recession coefficients of the multiple exponential runoff components range from 0.04 to 0.001 1/d. The derived hydraulic conductivity indicates a sandy, poorly silty aquifer for the base flow component. The peak of the fluoresceine breakthrough curve was observed after approximately 90 days, fitting well to the reciprocal of the base flow recession coefficient. The spring responds within a few hours to recharge events with sharp discharge peaks and negative electric conductivity and temperature peaks. Discharge separation based on electrical conductivity data reveals that only 20% of the discharge peak is recently recharged water. The natural and artificial tracers thus support the hydraulic model of two diverging storage components building up the aquifer of the relict rock glacier. While a fine grained (sandy, poorly silty although with larger embedded blocks) inner zone provides the base flow component, a coarse grained, blocky upper zone lacking fine-grained sediments provides the fast run off component.

Pauritsch, Marcus; Winkler, Gerfried; Kellerer-Pirklbauer, Andreas; Birk, Steffen

2013-04-01

328

A global data set of soil particle size properties  

NASA Technical Reports Server (NTRS)

A standardized global data set of soil horizon thicknesses and textures (particle size distributions) was compiled. This data set will be used by the improved ground hydrology parameterization designed for the Goddard Institute for Space Studies General Circulation Model (GISS GCM) Model 3. The data set specifies the top and bottom depths and the percent abundance of sand, silt, and clay of individual soil horizons in each of the 106 soil types cataloged for nine continental divisions. When combined with the World Soil Data File, the result is a global data set of variations in physical properties throughout the soil profile. These properties are important in the determination of water storage in individual soil horizons and exchange of water with the lower atmosphere. The incorporation of this data set into the GISS GCM should improve model performance by including more realistic variability in land-surface properties.

Webb, Robert S.; Rosenzweig, Cynthia E.; Levine, Elissa R.

1991-01-01

329

Correlations Between Physical and Hydraulic Properties and Uranium Desorption in Contaminated, Intact Sediment Cores  

NASA Astrophysics Data System (ADS)

An unlined disposal pond in the 300 Area of the Hanford Site received uranium-bearing liquid effluents associated with nuclear reactor fuel rod processing from 1943 to 1975. Contaminated sediments from the base and sides of the former pond were excavated and removed from the site in the early 1990s, but a uranium plume has persisted in the groundwater at concentrations exceeding the drinking water standard. The former process pond is located adjacent to the Columbia River and seasonal fluctuations in the river stage and water table provide a mechanism for resupplying residual uranium from the vadose zone to the groundwater when the lower vadose zone is periodically rewetted. Intact cores were collected from the site for measurements of physical, hydraulic, and geochemical properties. Multistep outflow experiments were also performed on the intact cores to determine permeability-saturation-capillary pressure relations. Pore water displaced during these experiments for two of the vadose zone cores was also analyzed for uranium. For a core containing finer-textured sediment classified as muddy sandy gravel, and a core containing coarser-textured sediment classified as gravel, the relative aqueous uranium concentrations increased by factors of 8.3 and 1.5, respectively, as the cores were desaturated and progressively smaller pore-size classes were drained. Aqueous concentrations of uranium in the extracted pore waters were up to 115 times higher than the current drinking water standard of 30 ppb. These results confirm that there is a continuing source of uranium in the vadose zone at the site, and are consistent with a hypothesis that the persistence of the groundwater uranium plume is also associated, in part, with rate-limited mass transfer from finer-textured sediments. The data from these and several other intact cores from the site are evaluated to explore relationships between physical and hydraulic properties and uranium desorption characteristics.

Rockhold, M. L.; Oostrom, M.; Wietsma, T. W.; Zachara, J. M.

2010-12-01

330

Use of flyash and biogas slurry for improving wheat yield and physical properties of soil.  

PubMed

This study explores the potential use of by-products of energy production, i.e., (i) flyash from coal-powered electricity generation and (ii) biogas slurry from agricultural waste treatment, as nutrient sources in agriculture. These residues are available in large amounts and their disposal is a major concern for the environment. As both residues contain considerable amounts of plant nutrients, their use as soil amendment may offer a promising win-win opportunity to improve crop production and, at the same time, preventing adverse environmental impacts of waste disposal. Effect of flyash and biogas slurry on soil physical properties and growth and yield of wheat (Triticum aestivum) was studied in a field experiment. Leaf area index, root length density and grain yield of wheat were higher in plots amended with flyash or biogas slurry compared to unamended plots. Both types of amendments reduced bulk density, and increased saturated hydraulic conductivity and moisture retention capacity of soil. The study showed that flyash and biogas slurry should be used as soil amendments for obtaining short-term and long-term benefits in terms of production increments and soil amelioration. PMID:16418901

Garg, R N; Pathak, H; Das, D K; Tomar, R K

2005-08-01

331

Specific Methods for the Evaluation of Hydraulic Properties in Fractured Hard-rock J.C. Marchala,*  

E-print Network

1 Specific Methods for the Evaluation of Hydraulic Properties in Fractured Hard-rock Aquifers J, marechal@ngri.res.in Abstract: Blocs underlined by fractures networks mainly compose hard-rock aquifers. The complexity of flows through fractures makes inadequate the use of classical techniques for the interpretation

Paris-Sud XI, Université de

332

Constraining soil hydraulic parameter and output uncertainty of the distributed hydrological MIKE SHE model using the GLUE framework  

NASA Astrophysics Data System (ADS)

Both calibration and uncertainty assessment are mandatory steps in today's modelling process. The former considers both the inputs (input variables and parameters) as well as model results. An exploratory investigation of the applicable parameter space results in a wide spectrum of values for a specific model output. By retaining only those model realizations that mimic reality in a sufficient way, inputs and associated response can be constrained, thereby quantifying the uncertainty involved. The generalized likelihood uncertainty estimation (GLUE) framework provides a structured methodology for this purpose.The study presented focuses on the applicability of the GLUE framework within the context of the distributed hydrological model MIKE SHE. Even though all significant processes involved are incorporated within the model, the problems of calibration and uncertainty assessment cannot be avoided. This has resulted in a quest for well-delineated effective parameters crucial for sound mechanistic model application. Being a complex model, the number of possible realizations using MIKE SHE is fairly small due to computing time, and an in-depth exploratory approach is impossible. On the other hand, several output variables are available aside from the hydrological river response, like water content in the soil profile or ground water level, which can be used for retaining realistic parameter sets.This study presents some preliminary results on the applicability of the GLUE-MIKE SHE framework and associated constrained preliminary parameter and output uncertainty values. Focus was given to the influence of soil hydraulic parameters on the hydrological behaviour of a small study basin. The soil hydraulic parameters were predicted using various pedo-transfer-function approaches and moisture retention measurements in the laboratory, and these distributions were then confronted with ranges of the constrained effective parameters. For the latter, the restrictions that were imposed based on behavioural acceptance were substantial. All the traditional methods show significant uncertainty, due to heterogeneity and model error, which cannot be disregarded. The first results suggest a reasonable match among effective parameters and laboratory measurements. The use of pedo-transfer-function distributions as effective parameters, however, may provide unacceptable results, even with liberal criteria.

Christiaens, K.; Feyen, J.

2002-02-01

333

Hygrothermal Simulation of Foundations: Part 1 - Soil Material Properties  

SciTech Connect

The hygrothermal performance of soils coupled to buildings is a complicated process. A computational approach for heat transfer through the ground has been well defined (EN ISO 13370:2007, 2007), and simplified methods have been developed (Staszczuk, Radon, and Holm 2010). However, these approaches generally ignore the transfer of soil moisture, which is not negligible (Janssen, Carmeliet, and Hens 2004). This study is divided into several parts. The intention of the first part is to gather, comprehend and adapt soil properties from Soil Science. The obtained information must be applicable to related tasks in Building Science and validated with hygrothermal calculation tools. Future parts of this study will focus on the validation aspect of the soil properties to be implemented. Basic changes in the software code may be requested at this time. Different types of basement construction will be created with a hygrothermal calculation tool, WUFI. Simulations from WUFI will be compared with existing or ongoing measurements. The intentions of the first part of this study have been fulfilled. The soil properties of interest in Building Science have been defined for 12 different soil textures. These properties will serve as input parameters when performing hygrothermal calculations of building constructions coupled to soil materials. The reliability of the soil parameters will be further evaluated with measurements in Part 2.

Kehrer, Manfred [ORNL; Pallin, Simon B [ORNL

2012-10-01

334

Physical and hydraulic properties of baked ceramic aggregates used for plant growth medium  

NASA Technical Reports Server (NTRS)

Baked ceramic aggregates (fritted clay, arcillite) have been used for plant research both on the ground and in microgravity. Optimal control of water and air within the root zone in any gravity environment depends on physical and hydraulic properties of the aggregate, which were evaluated for 0.25-1-mm and 1-2-mm particle size distributions. The maximum bulk densities obtained by any packing technique were 0.68 and 0.64 g cm-3 for 0.25-1-mm and 1-2-mm particles, respectively. Wettable porosity obtained by infiltration with water was approximately 65%, substantially lower than total porosity of approximately 74%. Aggregate of both particle sizes exhibited a bimodal pore size distribution consisting of inter-aggregate macropores and intra-aggregate micropores, with the transition from macro- to microporosity beginning at volumetric water content of approximately 36% to 39%. For inter-aggregate water contents that support optimal plant growth there is 45% change in water content that occurs over a relatively small matric suction range of 0-20 cm H2O for 0.25-1-mm and 0 to -10 cm H2O for 1-2-mm aggregate. Hysteresis is substantial between draining and wetting aggregate, which results in as much as a approximately 10% to 20% difference in volumetric water content for a given matric potential. Hydraulic conductivity was approximately an order of magnitude higher for 1-2-mm than for 0.25-1-mm aggregate until significant drainage of the inter-aggregate pore space occurred. The large change in water content for a relatively small change in matric potential suggests that significant differences in water retention may be observed in microgravity as compared to earth.

Steinberg, Susan L.; Kluitenberg, Gerard J.; Jones, Scott B.; Daidzic, Nihad E.; Reddi, Lakshmi N.; Xiao, Ming; Tuller, Markus; Newman, Rebecca M.; Or, Dani; Alexander, J. Iwan. D.

2005-01-01

335

Magnetic properties of alluvial soils polluted with heavy metals  

NASA Astrophysics Data System (ADS)

Magnetic properties of soils, reflecting mineralogy, concentration and grain-size distribution of Fe-oxides, proved to be useful tool in assessing the soil properties in terms of various environmental conditions. Measurement of soil magnetic properties presents a convenient method to investigate the natural environmental changes in soils as well as the anthropogenic pollution of soils with several risk elements. The effect of fluvial pollution with Cd, Cu, Pb and Zn on magnetic soil properties was studied on highly contaminated alluvial soils from the mining/smelting district (P?íbram; CZ) using a combination of magnetic and geochemical methods. The basic soil characteristics, the content of heavy metals, oxalate, and dithionite extractable iron were determined in selected soil samples. Soil profiles were sampled using HUMAX soil corer and the magnetic susceptibility was measured in situ, further detailed magnetic analyses of selected distinct layers were carried out. Two types of variations of magnetic properties in soil profiles were observed corresponding to indentified soil types (Fluvisols, and Gleyic Fluvisols). Significantly higher values of topsoil magnetic susceptibility compared to underlying soil are accompanied with high concentration of heavy metals. Sequential extraction analysis proved the binding of Pb, Zn and Cd in Fe and Mn oxides. Concentration and size-dependent parameters (anhysteretic and isothermal magnetization) were measured on bulk samples in terms of assessing the origin of magnetic components. The results enabled to distinguish clearly topsoil layers enhanced with heavy metals from subsoil samples. The dominance of particles with pseudo-single domain behavior in topsoil and paramagnetic/antiferromagnetic contribution in subsoil were observed. These measurements were verified with room temperature hysteresis measurement carried out on bulk samples and magnetic extracts. Thermomagnetic analysis of magnetic susceptibility measured on magnetic extracts indicated the presence of magnetite/maghemite in the uppermost layers, and strong mineralogical transformation of iron oxyhydroxides during heating. Magnetic techniques give valuable information about the soil Fe oxides, which are useful for investigation of the environmental effects in soil. Key words: magnetic methods, Fe oxides, pollution, alluvial soils.

Dlouha, S.; Petrovsky, E.; Boruvka, L.; Kapicka, A.; Grison, H.

2012-04-01

336

Stimulatory Effects of Arsenic-Tolerant Soil Fungi on Plant Growth Promotion and Soil Properties  

PubMed Central

Fifteen fungi were obtained from arsenic-contaminated agricultural fields in West Bengal, India and examined for their arsenic tolerance and removal ability in our previous study. Of these, the four best arsenic-remediating isolates were tested for plant growth promotion effects on rice and pea in the present study. A greenhouse-based pot experiment was conducted using soil inocula of individual fungi. The results indicated a significant (P<0.05) increase in plant growth and improvement of soil properties in inoculated soils compared to the control. A significant increase in plant growth was recorded in treated soils and varied from 16–293%. Soil chemical and enzymatic properties varied from 20–222% and 34–760%, respectively, in inoculated soil. Plants inoculated with inocula of Westerdykella and Trichoderma showed better stimulatory effects on plant growth and soil nutrient availability than Rhizopus and Lasiodiplodia. These fungi improved soil nutrient content and enhanced plant growth. These fungi may be used as bioinoculants for plant growth promotion and improved soil properties in arsenic-contaminated agricultural soils. PMID:23047145

Srivastava, Pankaj Kumar; Shenoy, Belle Damodara; Gupta, Manjul; Vaish, Aradhana; Mannan, Shivee; Singh, Nandita; Tewari, Shri Krishna; Tripathi, Rudra Deo

2012-01-01

337

Combining phytoextraction and biochar addition improves soil biochemical properties in a soil contaminated with Cd.  

PubMed

The main goal of phytoremediation is to improve ecosystem functioning. Soil biochemical properties are considered as effective indicators of soil quality and are sensitive to various environmental stresses, including heavy metal contamination. The biochemical response in a soil contaminated with cadmium was tested after several treatments aimed to reduce heavy metal availability including liming, biochar addition and phytoextraction using Amaranthus tricolor L. Two biochars were added to the soil: eucalyptus pyrolysed at 600°C (EB) and poultry litter at 400°C (PLB). Two liming treatments were chosen with the aim of bringing soil pH to the same values as in the treatments EB and PLB. The properties studied included soil microbial biomass C, soil respiration and the activities of invertase, ?-glucosidase, ?-glucosaminidase, urease and phosphomonoesterase. Both phytoremediation and biochar addition improved soil biochemical properties, although results were enzyme specific. For biochar addition these changes were partly, but not exclusively, mediated by alterations in soil pH. A careful choice of biochar must be undertaken to optimize the remediation process from the point of view of metal phytoextraction and soil biological activity. PMID:25010741

Lu, Huanping; Li, Zhian; Fu, Shenglei; Méndez, Ana; Gascó, Gabriel; Paz-Ferreiro, Jorge

2015-01-01

338

The development of detailed soil maps on the basis of interpolation of data on soil properties  

NASA Astrophysics Data System (ADS)

A methodology for creating detailed soil maps on the basis of a dense grid of soil testing points and the numerical interpolation of experimental data on the soil properties is discussed. The study of the soil cover patterns combines regular sampling grids with equal spacing and additional sampling points chosen with due account for the soil cover specificity in particular areas. Soil diagnostics are performed at each of the points, and the diagnostic features of the soils are recorded in the field. In a laboratory, these data are arranged into a database, and a legend to the soil map is created. The necessary and sufficient set of the quantitative soil characteristics is selected, and quantitative criteria of the boundaries between the separate soil polygons are determined on the basis of numerical interpolation. Algorithms to delineate soil polygons on the basis of the selected indices are developed. Separate thematic map layers are produced for each of the selected soil characteristics. An integral soil map for the investigated area is obtained via the superposition of these layers. The thickness and/or the depths of the upper/lower boundaries of the soil layer with definite diagnostic characteristics making it possible to distinguish the given soil from its neighbors are used as the criteria for delineating the boundaries between soil polygons. Special criteria based on the proportions between the thicknesses or depths of several layers can also be applied for this purpose. The creation of a detailed soil map of a plot on the Kamennaya Steppe is discussed as an example of the practical application of this methodology.

Khitrov, N. B.

2012-10-01

339

Combining steam injection with hydraulic fracturing for the in situ remediation of the unsaturated zone of a fractured soil polluted by jet fuel.  

PubMed

A steam injection pilot-scale experiment was performed on the unsaturated zone of a strongly heterogeneous fractured soil contaminated by jet fuel. Before the treatment, the soil was stimulated by creating sub-horizontal sand-filled hydraulic fractures at three depths. The steam was injected through one hydraulic fracture and gas/water/non-aqueous phase liquid (NAPL) was extracted from the remaining fractures by applying a vacuum to extraction wells. The injection strategy was designed to maximize the heat delivery over the entire cell (10 m × 10 m × 5 m). The soil temperature profile, the recovered NAPL, the extracted water, and the concentrations of volatile organic compounds (VOCs) in the gas phase were monitored during the field test. GC-MS chemical analyses of pre- and post-treatment soil samples allowed for the quantitative assessment of the remediation efficiency. The growth of the heat front followed the configuration of hydraulic fractures. The average concentration of total hydrocarbons (g/kg of soil) was reduced by ? 43% in the upper target zone (depth = 1.5-3.9 m) and by ? 72% over the entire zone (depth = 1.5-5.5 m). The total NAPL mass removal based on gas and liquid stream measurements and the free-NAPL product were almost 30% and 2%, respectively, of those estimated from chemical analyses of pre- and post-treatment soil samples. The dominant mechanisms of soil remediation was the vaporization of jet fuel compounds at temperatures lower than their normal boiling points (steam distillation) enhanced by the ventilation of porous matrix due to the forced convective flow of air. In addition, the significant reduction of the NAPL mass in the less-heated deeper zone may be attributed to the counter-current imbibition of condensed water from natural fractures into the porous matrix and the gravity drainage associated with seasonal fluctuations of the water table. PMID:21030134

Nilsson, Bertel; Tzovolou, Dimitra; Jeczalik, Maciej; Kasela, Tomasz; Slack, William; Klint, Knud E; Haeseler, Frank; Tsakiroglou, Christos D

2011-03-01

340

Detection and quantification of rock physics properties for improved hydraulic fracturing in hydrocarbon-bearing shales.  

E-print Network

??Horizontal drilling and hydraulic stimulation make hydrocarbon production from organic-rich shales economically viable. Identification of suitable zones to drill a horizontal well and to initiate… (more)

Montaut, Antoine Marc Marie

2012-01-01

341

Hydrogeologic setting, hydraulic properties, and ground-water flow at the O-Field area of Aberdeen Proving Ground, Maryland  

USGS Publications Warehouse

The U.S. Army disposed chemical agents, laboratory materials, and unexploded ordnance at O-Field in the Edgewood area of Aberdeen Proving Ground, Maryland, from before World War II until at least the 1950's. Soil, ground water, surface water,and wetland sediments in the O-Field area were contaminated from the disposal activity. A ground-water-flow model of the O-Field area was constructed by the U.S. Geological Survey (USGS) in 1989 to simulate flow in the central and southern part of the Gunpowder Neck. The USGS began an additional study of the contamination in the O-Field area in cooperation with the U.S. Army in 1990 to (1) further define the hydrogeologic framework of the O-Field area, (2) characterize the hydraulic properties of the aquifers and confining units, and (3) define ground-water flow paths at O-Field based on the current data and simulations of ground-water flow. A water-table aquifer, an upper confining unit, and an upper confined aquifer comprise the shallow ground-water aquifer system of the O-Field area. A lower confining unit, through which ground-water movement is negligible, is considered a lower boundary to the shallow aquifer system. These units are all part of the Pleistocene Talbot Formation. The model developed in the previous study was redesigned using the data collected during this study and emphasized New O-Field. The current steady-state model was calibrated to water levels of June 1993. The rate of ground-water flow calculated by the model was approximately 0.48 feet per day (ft/d) and the rate determined from chlorofluorocarbon dates was approximately 0.39 ft/d.

Banks, W.S.; Smith, B.S.; Donnelly, C.A.

1996-01-01

342

ORGANIC CARBON INFLUENCES ON SOIL PARTICLE DENSITY AND RHEOLOGICAL PROPERTIES  

Technology Transfer Automated Retrieval System (TEKTRAN)

Soil particle density (ps) is not routinely measured and is often assumed to range between 2.60 and 2.70 Mg/cubic meter or constant (2.65 Mg/cubic meter) when estimating essential properties such as porosity, and volumetric water and air relations. Values of ps for the same soil may, however, differ...

343

Tillage effects on soil physical properties, sugarbeet yield and quality  

Technology Transfer Automated Retrieval System (TEKTRAN)

Tillage influences the soil-water-plant ecosystem thereby affecting crop yield and quality. The effects of tillage on soil physical properties, sugarbeet (Beta vulgaris L.) yield and quality were evaluated. A field study comprises of three tillage practices: no tillage (NT) shallow (ST) of 10-cm and...

344

Soil properties associated with the tree decline ‘Mundulla Yellows’  

Microsoft Academic Search

Czerniakowski, B., Crnov, R., Smith, I. W. and Luck, J.E. 2006. Mundulla Yellows (MY) is a progressive dieback syndrome of Eucalyptus and other native species that was first reported in the 1970s. Despite being observed in Australia for over 30 years, the cause of MY has not been determined. To investigate the role of soil properties in MY, foliage and soil

Barbara Czerniakowski; Rosa Crnov; Ian W. Smith; Jo E. Luck

2006-01-01

345

Effects of fire on properties of forest soils: a review  

Microsoft Academic Search

Many physical, chemical, mineralogical, and biological soil properties can be affected by forest fires. The effects are chiefly a result of burn severity, which consists of peak temperatures and duration of the fire. Climate, vegetation, and topography of the burnt area control the resilience of the soil system; some fire-induced changes can even be permanent. Low to moderate severity fires,

Giacomo Certini

2005-01-01

346

SOIL PROPERTIES OF SITES USED FOR COMPOSTING ANIMAL MANURE  

Technology Transfer Automated Retrieval System (TEKTRAN)

Long-term animal manure composting creates zones of high soil nutrient and salinity. Once the composting operation is terminated, there is a need to reclaim the sites for agricultural crops. The objective of this study is to evaluate soil properties and performance of corn (Zea mays), sorghum (Sor...

347

Mechanical and hydraulic properties of Nankai accretionary prism sediments: Effect of stress path  

NASA Astrophysics Data System (ADS)

We have conducted triaxial deformation experiments along different loading paths on prism sediments from the Nankai Trough. Different load paths of isotropic loading, uniaxial strain loading, triaxial compression (at constant confining pressure, Pc), undrained Pc reduction, drained Pc reduction, and triaxial unloading at constant Pc, were used to understand the evolution of mechanical and hydraulic properties under complicated stress states and loading histories in accretionary subduction zones. Five deformation experiments were conducted on three sediment core samples for the Nankai prism, specifically from older accreted sediments at the forearc basin, underthrust slope sediments beneath the megasplay fault, and overthrust Upper Shikoku Basin sediments along the frontal thrust. Yield envelopes for each sample were constructed based on the stress paths of Pc-reduction using the modified Cam-clay model, and in situ stress states of the prism were constrained using the results from the other load paths and accounting for horizontal stress. Results suggest that the sediments in the vicinity of the megasplay fault and frontal thrust are highly overconsolidated, and thus likely to deform brittle rather than ductile. The porosity of sediments decreases as the yield envelope expands, while the reduction in permeability mainly depends on the effective mean stress before yield, and the differential stress after yield. An improved understanding of sediment yield strength and hydromechanical properties along different load paths is necessary to treat accurately the coupling of deformation and fluid flow in accretionary subduction zones.

Kitajima, Hiroko; Chester, Frederick M.; Biscontin, Giovanna

2012-10-01

348

Plot scale continuous modelling of runoff in a maize cropping system with dynamic soil surface properties  

NASA Astrophysics Data System (ADS)

SummaryThe evaluation of the hydrological impact of crop management practices requires models sensitive to temporal changes in surface properties and especially to changes in surface roughness and saturated hydraulic conductivity. This study reports on the development and application of a new, continuous, physically-based, spatially-distributed and plot-scale runoff model that required only five adjusted parameters. The results of the model were compared with runoff measurements taken over two years on 90 m 2 runoff plots in a continuous maize cropping system with and without winter cover crop. On the basis of the daily predicted runoff, the model gave good fits for the intercropping period (Nash-Sutcliffe efficiency coefficient from 0.80 to 0.94) and poor to reasonable fits for the maize period (Nash-Sutcliffe efficiency coefficient from less than 0 up to 0.33). The poor results are in part attributed to the fact that only decreases in hydraulic conductivity can be modelled at present, whereas this property may in reality increase over time in some cases. Moreover, runoff hydrograms for individual storms are relatively well predicted dynamically. The large impact of semi-permanent wheel tracks on runoff production is also pointed out. Finally, a sensitivity analysis is performed and the relevance of incorporating dynamic soil properties in continuous modelling of runoff is underlined.

Laloy, E.; Bielders, C. L.

2008-02-01

349

Hygrothermal Simulations of Foundations: Part 1 - Soil Material Properties  

SciTech Connect

Hygrothermal performance of soils coupled to buildings is a complicated process. The computational approach for heat transfer via the ground is well defined (EN-ISO-13370:, 2007) together with simplified methods (Staszczuk, Radon, & Holm). Though the soil moisture transfer is generally ignored, it is proven not negligible (Janssen, Carmeliet, & Hens, 2004). Even though reliable material properties of soils are required to perform realistic hygrothermal calculations of soils coupled to buildings, such material properties have not been well defined in hygrothermal calculations tools. Typical building constructions which are greatly influenced by soils are basements, crawl spaces and slab on grade and reliable hygrothermal performance of such construction are highly requested; as it is ranked within the top 10 Building America Enclosure Research Ideas according to Enclosures STC - Residential Energy Efficiency Stakeholder Meeting, February 29, 2012 Austin, TX. There exists an extensive amount of measurements on soil properties in Soil Science though this information must be gathered as well as adapted to be applicable in Building Science and for hygrothermal simulation purposes. Soil properties are important when analyzing and designing both new building constructions and retrofitting measures, where the outer boundary of the buildings enclosure consists of soil materials. Concerning basement energy retrofits, interior solutions of improving the energy demand has to cooperate with the existing soil properties and must therefore be designed thereafter. In concerns of exterior retrofits, the soil material can be replaced, if needed, with a more suitable filling material, though this approach applies only for basement walls. The soil material beneath the basement floor can naturally not be replaced hence the soil properties of this part of the buildings enclosure still must be taken into consideration. This study is divided into several parts. The intention of the first part is to gather, comprehend and adapt soil properties from soil science. The obtained information must be applicable for Building Science related tasks and validated in hygrothermal calculation tools hence the second part of this study will focus on validation of the implemented soil properties. Basic changes in the software code may be requested as well. Different basement constructions will be created with a hygrothermal calculation tool, WUFI, from which simulations will be compared with existing or on-going measurements. The final outcome of the study is to enable an evaluation of several soil types in several climate zones combined with a number of basement assemblies. The study will define which type of soil together with a certain building construction which is considered most and least reliable in concerns of energy consumption and moisture safety. Further, what influences different soils will have on the total energy loss via the ground and if the performance of a different soils can be measured by a comparison of soil properties solely.

Pallin, Simon B [ORNL; Kehrer, Manfred [ORNL

2013-01-01

350

Influence of soil properties on the effect of silver nanomaterials on microbial activity in five soils.  

PubMed

We investigated the effects of silver nanomaterials (AgNMs) on five well-characterized soils with distinct physicochemical properties using two standardized test systems. The carbon transformation test (OECD 217) showed minimal sensitivity whereas the ammonia oxidizing bacteria test (ISO 15685) showed extreme sensitivity over 28 days of exposure. AgNM toxicity was compared with the physicochemical properties of the soils, revealing that toxicity declined with increasing clay content and increasing pH. AgNM toxicity did not appear to be affected by the organic carbon content of the soil. Our results showed that AgNM toxicity cannot be attributed to any single soil property but depends on the same parameters that determine the toxicity of conventional chemicals. Recommendations in the test guidelines for soil ecotoxicity studies are therefore applicable to AgNMs as well as conventional chemicals. PMID:25463729

Schlich, Karsten; Hund-Rinke, Kerstin

2014-11-10

351

Determining the Porosity and Saturated Hydraulic Conductivity of Binary Mixtures  

SciTech Connect

Gravels and coarse sands make up significant portions of some environmentally important sediments, while the hydraulic properties of the sediments are typically obtained in the laboratory using only the fine fraction (e.g., <2 mm or 4.75 mm). Researchers have found that the content of gravel has significant impacts on the hydraulic properties of the bulk soils. Laboratory experiments were conducted to measure the porosity and the saturated hydraulic conductivity of binary mixtures with different fractions of coarse and fine components. We proposed a mixing-coefficient model to estimate the porosity and a power-averaging method to determine the effective particle diameter and further to predict the saturated hydraulic conductivity of binary mixtures. The proposed methods could well estimate the porosity and saturated hydraulic conductivity of the binary mixtures for the full range of gravel contents and was successfully applied to two data sets in the literature.

Zhang, Z. F.; Ward, Anderson L.; Keller, Jason M.

2009-09-27

352

Determining the Porosity and Saturated Hydraulic Conductivity of Binary Mixtures  

SciTech Connect

Gravels and coarse sands make up significant portions of some environmentally important sediments, while the hydraulic properties of the sediments are typically obtained in the laboratory using only the fine fraction (e.g., <2 mm or 4.75 mm). Researchers have found that the content of gravel has significant impacts on the hydraulic properties of the bulk soils. Laboratory experiments were conducted to measure the porosity and the saturated hydraulic conductivity of binary mixtures with different fractions of coarse and fine components. We proposed a mixing-coefficient model to estimate the porosity and a power-averaging method to determine the effective particle diameter and further to predict the saturated hydraulic conductivity of binary mixtures. The proposed methods could well estimate the porosity and saturated hydraulic conductivity of the binary mixtures for the full range of gravel contents and was successfully applied to two data sets in the literature.

Zhang, Z. F.; Ward, Anderson L.; Keller, Jason M.

2011-02-14

353

Spatial and Temporal Variability of Hydraulic Properties in the Russian River Streambed, Central Sonoma, County, CA  

Microsoft Academic Search

Temporal and spatial variations of flux and vertical hydraulic conductivity were measured in the Russian River streambed in Sonoma County, California. In-situ vertical hydraulic conductivity measurements were made using a modified seepage meter, equipped with mini-piezometers and sediment was collected with a bucket and shovel. We sampled three different streambed (near bank, midpoint, and thalweg) locations at five different sample

M. Laforce; P. Gorman; J. Constantz

2004-01-01

354

Quasi-open loop hydraulic ram incremental actuator with power conserving properties  

Microsoft Academic Search

An electric stepping motor, operated by command signals from a computer or a microprocessor, rotates a rotary control member of a distributor valve, for sequencing hydraulic pressure and hence flow to the cylinders of an axial piston hydraulic machine. A group of the cylinders are subjected to pressure and flow and the remaining cylinders are vented to a return line.

E. T. Raymond; C. W. Robinson

1982-01-01

355

Remote sensing of soil properties in precision agriculture: A review  

NASA Astrophysics Data System (ADS)

The success of precision agriculture (PA) depends strongly upon an efficient and accurate method for in-field soil property determination. This information is critical for farmers to calculate the proper amount of inputs for best crop performance and least environmental effect. Grid sampling, as a traditional way to explore in-field soil variation, is no longer considered appropriate since it is labor intensive, time consuming and lacks spatial exhaustiveness. Remote sensing (RS) provides a new tool for PA information gathering and has advantages of low cost, rapidity, and relatively high spatial resolution. Great progress has been made in utilizing RS for in-field soil property determination. In this article, recent publications on the subject of RS of soil properties in PA are reviewed. It was found that a large array of agriculturally-important soil properties (including textures, organic and inorganic carbon content, macro- and micro-nutrients, moisture content, cation exchange capacity, electrical conductivity, pH, and iron) were quantified with RS successfully to the various extents. The applications varied from laboratory-analysis of soil samples with a bench-top spectrometer to field-scale soil mapping with satellite hyper-spectral imagery. The visible and near-infrared regions are most commonly used to infer soil properties, with the ultraviolet, mid-infrared, and thermal-infrared regions have been used occasionally. In terms of data analysis, MLR, PCR, and PLSR are three techniques most widely used. Limitations and possibilities of using RS for agricultural soil property characterization were also identified in this article.

Ge, Yufeng; Thomasson, J. Alex; Sui, Ruixiu

2011-09-01

356

pH-dependent leaching behaviour and other performance properties of cement-treated mixed contaminated soil.  

PubMed

Portland cement has been widely used for stabilisation/solidification (S/S) treatment of contaminated soils. However, there is a dearth of literature on pH-dependent leaching of contaminants from cement-treated soils. This study investigates the leachability of Cu, Pb, Ni, Zn and total petroleum hydrocarbons (TPH) from a mixed contaminated soil. A sandy soil was spiked with 3000 mg/kg each of Cd, Cu, Pb, Ni and Zn, and 10,000 mg/kg of diesel, and treated with ordinary Portland cement (CEM I). Four different binder dosages, 5%, 10%, 15% and 20% (m/m) and different water contents ranging from 13%-19% dry weight were used in order to find a safe operating envelope for the treatment process. The pH-dependent leaching behaviour of the treated soil was monitored over an 84-day period using a 3-point acid neutralisation capacity (ANC) test. The monolithic leaching test was also conducted. Geotechnical properties such as unconfined compressive strength (UCS), hydraulic conductivity and porosity were assessed over time. The treated soils recorded lower leachate concentrations of Ni and Zn compared to the untreated soil at the same pH depending on binder dosage. The binder had problems with Pb stabilisation and TPH leachability was independent of pH and binder dosage. The hydraulic conductivity of the mixes was generally of the order, 10(-8) m/sec, while the porosity ranged from 26%-44%. The results of selected performance properties are compared with regulatory limits and the range of operating variables that lead to acceptable performance described. PMID:23520871

Kogbara, Reginald B; Al-Tabbaa, Abir; Yi, Yaolin; Stegemann, Julia A

2012-01-01

357

Running heading: Water retention properties of the clay in clayey soils Water retention properties of the clay in soils developed  

E-print Network

1 Running heading: Water retention properties of the clay in clayey soils Water retention. E-mail: ary.bruand@orleans.inra.fr Summary We have investigated the water retention properties retention properties have been studied from -10 hPa to -15 000 hPa water potential using small clods

Paris-Sud XI, Université de

358

Impact of light quality on leaf and shoot hydraulic properties: a case study in silver birch (Betula pendula)pce_2306 1079..1087  

E-print Network

Impact of light quality on leaf and shoot hydraulic properties: a case study in silver birch Responses of leaf and shoot hydraulic conductance to light quality were examined on shoots of silver birch factors had effect on KP. The highest values of Klb were recorded under the blue light (3.63 and 3.13 ¥ 10

Sack, Lawren

359

SOIL MOISTURE CHARACTERISTICS IN UPPER PART OF HINDON RIVER CATCHMENT  

E-print Network

1 SOIL MOISTURE CHARACTERISTICS IN UPPER PART OF HINDON RIVER CATCHMENT C. P. Kumar* Vijay Kumar** Vivekanand Singh*** ABSTRACT Knowledge of the physics of soil water movement is crucial to the solution for estimating the soil hydraulic properties are required for prediction of soil water flow. This paper presents

Kumar, C.P.

360

Statistical-physical model of the hydraulic conductivity  

NASA Astrophysics Data System (ADS)

The water content in unsaturated subsurface soil layer is determined by processes of exchanging mass and energy between media of soil and atmosphere, and particular members of layered media. Generally they are non-homogeneous on different scales, considering soil porosity, soil texture including presence of vegetation elements in the root zone, and canopy above the surface, and varying biomass density of plants above the surface in clusters. That heterogeneity determines statistically effective values of particular physical properties. This work considers mainly those properties which determine the hydraulic conductivity of soil. This property is necessary for characterizing physically water transfer in the root zone and access of nutrient matter for plants, but it also the water capacity on the field scale. The temporal variability of forcing conditions and evolutionarily changing vegetation causes substantial effects of impact on the water capacity in large scales, bringing the evolution of water conditions in the entire area, spanning a possible temporal state in the range between floods and droughts. The dynamic of this evolution of water conditions is highly determined by vegetation but is hardly predictable in evaluations. Hydrological models require feeding with input data determining hydraulic properties of the porous soil which are proposed in this paper by means of the statistical-physical model of the water hydraulic conductivity. The statistical-physical model was determined for soils being typical in Euroregion Bug, Eastern Poland. The model is calibrated on the base of direct measurements in the field scales, and enables determining typical characteristics of water retention by the retention curves bounding the hydraulic conductivity to the state of water saturation of the soil. The values of the hydraulic conductivity in two reference states are used for calibrating the model. One is close to full saturation, and another is for low water content far from saturation, in a particular case of the soil type. Effects of calibrating a soil depends on assumed ranges of soil properties engaged to recognizing the soil type. Among those properties, the key role is for the bulk density, the porosity and its dependence on the specific area of the soil. The aim of this work is to provide such variables of auxiliary data to SMOS, which would bring a relation of the soil moisture to the water capacity, under retrieving SM from SMOS L1C data. * The work was financially supported in part by the ESA Programme for European Cooperating States (PECS), No.98084 "SWEX-R, Soil Water and Energy Exchange/Research", AO3275.

Usowicz, B.; Marczewski, W.; Usowicz, J. B.; Lukowski, M. I.

2012-04-01

361

Effects of partial root-zone irrigation on hydraulic conductivity in the soil–root system of maize plants  

PubMed Central

Effects of partial root-zone irrigation (PRI) on the hydraulic conductivity in the soil–root system (Lsr) in different root zones were investigated using a pot experiment. Maize plants were raised in split-root containers and irrigated on both halves of the container (conventional irrigation, CI), on one side only (fixed PRI, FPRI), or alternately on one of two sides (alternate PRI, APRI). Results show that crop water consumption was significantly correlated with Lsr in both the whole and irrigated root zones for all three irrigation methods but not with Lsr in the non-irrigated root zone of FPRI. The total Lsr in the irrigated root zone of two PRIs was increased by 49.0–92.0% compared with that in a half root zone of CI, suggesting that PRI has a significant compensatory effect of root water uptake. For CI, the contribution of Lsr in a half root zone to Lsr in the whole root zone was ?50%. For FPRI, the Lsr in the irrigated root zone was close to that of the whole root zone. As for APRI, the Lsr in the irrigated root zone was greater than that of the non-irrigated root zone. In comparison, the Lsr in the non-irrigated root zone of APRI was much higher than that in the dried zone of FPRI. The Lsr in both the whole and irrigated root zones was linearly correlated with soil moisture in the irrigated root zone for all three irrigation methods. For the two PRI treatments, total water uptake by plants was largely determined by the soil water in the irrigated root zone. Nevertheless, the non-irrigated root zone under APRI also contributed to part of the total crop water uptake, but the continuously non-irrigated root zone under FPRI gradually ceased to contribute to crop water uptake, suggesting that it is the APRI that can make use of all the root system for water uptake, resulting in higher water use efficiency. PMID:21527627

Hu, Tiantian; Kang, Shaozhong; Li, Fusheng; Zhang, Jianhua

2011-01-01

362

Linking soil and sediment properties for research on biogeochemical cycles  

NASA Astrophysics Data System (ADS)

Conventional perspectives on soil erosion include the on-site damage to soil and reductions in crop yield, as well as the resulting off-site effects on water quality, runoff and sediment loads in rivers. Our evolving understanding of the Earth System has added a new dimension to the role of soil erosion within the global geochemical cycles. First, the relevance of soil as a nutrient and Carbon (C) pool was recognized. Initially, the role of soils in the global C cycle was largely considered to be limited to a vertical exchange of greenhouse house gases (GHG) between vegetation, soil and atmosphere and thus mostly studied by soil scientists, plant ecologists and climatologists. Even Critical Zone research focused mostly on weathering and regolith properties and ignored lateral fluxes of dissolved or particulate organic matter. Since the late 1990s, a wider role of soils in biogeochemical cycles has emerged. Recent estimates place the lateral movement of C between soil and sediment pools in terrestrial ecosystems (including rivers and lakes) at approximately 0.6 to 1.5 Gt per year. Some of the eroded C is replaced by photosynthesis from the atmosphere, but at a cost of additional emissions, for example due to fertilizer production. The long-term fate of the eroded and deposited soil organic matter is subject to an open debate and suffers from a lack of reliable spatial information on lateral C fluxes and its subsequent fate in terrestrial ecosystems. The connection between soil C pool, GHG emissions and erosion illustrates the relevance of surface processes for the C fluxes between Earth's spheres. Accordingly, soil is now considered as mobile system to make accurate predictions about the consequences of global change for terrestrial biogeochemical cycles and climate feedbacks. This expanded perspective on soils as dynamic pool of weathering regolith, sediment, nutrients and C at the interface between the geospheres requires the analysis of relevant soil properties, i.e. nutrient or C content, with regards to their mobility within local, regional and global biogeochemical cycles, including past, current and future rates of transfer. In this presentation, an initial framework illustrating a concept for linking soil properties and the mobility (lateral and vertical) of nutrients and organic matter critical for environmental conditions and services is developed.

Kuhn, Nikolaus J.

2013-04-01

363

PREDICTING RUNOFF AND SOIL EROSION FROM A STIFF-STEMMED GRASS HEDGE SYSTEM IN A SMALL WATERSHED  

Technology Transfer Automated Retrieval System (TEKTRAN)

Planting of vegetative stiff-stemmed grass hedges as an erosion control practice may influence surface runoff by altering soil hydraulic properties. The objective of our study was to evaluate the effects of measured soil hydraulic properties as influenced by grass hedges on runoff and sediment yiel...

364

The influence of soil properties on the toxicity of molybdenum to three species of soil invertebrates.  

PubMed

Mo toxicity to earthworms (Eisenia andrei), Collembola (Folsomia candida) and enchytraeids (Enchytraeus crypticus) was determined in 10 European soils and a standard artificial soil, freshly spiked with Na(2)MoO(4), after 28 days exposure. Mo affected survival only in three low pH sandy soils; in all other soils LC50 was >3200 mg Mo/kg dry soil. EC50 values for the reproduction toxicity of Mo were 129-2378 mg/kg for earthworms, 72->3396 mg/kg for Collembola, and 301->2820 mg/kg for enchytraeids. Variation in toxicity among soils could not be explained by differences in available (pore water, water and 0.01 M CaCl(2) extractable) Mo concentrations. Clay content best predicted the EC50 for Mo toxicity to earthworms, while toxicity of Mo for enchytraeids was best described by soil pH. For Collembola no relationships could be derived due to the absence of toxicity in most soils. Soil properties had a strong but species-specific effect on Mo toxicity to soil invertebrates. PMID:20951431

van Gestel, Cornelis A M; Borgman, Eef; Verweij, Rudo A; Ortiz, Maria Diez

2011-01-01

365

Determination of heterogeneities in the hydraulic properties of a phreatic aquifer from tidal level fluctuations: a case in Argentina  

NASA Astrophysics Data System (ADS)

A well-known analytical solution of Jacob (1950) for groundwater flow due to tidal-wave propagation, together with field measurements along a complete tidal cycle and geological data, were used to evaluate the heterogeneities in the hydraulic properties of a phreatic aquifer located next to the River Ajo in the coastal plain environment of the southern sector of the Samborombon Bay wetland, Argentina. From the analysis of water-table fluctuations in a set of monitoring wells located along a riverbank-normal transect, it was possible to quantify the piecewise spatial variations of the hydraulic diffusivity of the phreatic aquifer. The results show the strong lateral variations of the sedimentary environment due to the influence of the different transport and deposition agents that characterize the coastal plain. The known thickness of the phreatic aquifer and the estimated range of the specific yield allowed the hydraulic conductivity to be identified as the most influential factor. [Jacob CE (1950) Flow of ground water. In: Rouse H (ed) Engineering Hydraulics. Wiley, New York

Carol, Eleonora S.; Kruse, Eduardo E.; Pousa, Jorge L.; Roig, Alejandro R.

2009-11-01

366

Thermal properties of soils: effect of biochar application  

NASA Astrophysics Data System (ADS)

Thermal properties (thermal conductivity, heat capacity and thermal diffusivity) have a significant effect on the soil surface energy partitioning and resulting in the temperature distribution. Thermal properties of soil depend on water content, bulk density and organic matter content. An important source of organic matter is biochar. Biochar as a material is defined as: "charcoal for application as a soil conditioner". Biochar is generally associated with co-produced end products of pyrolysis. Many different materials are used as biomass feedstock for biochar, including wood, crop residues and manures. Additional predictions were done for terra preta soil (also known as "Amazonian dark earth"), high in charcoal content, due to adding a mixture of charcoal, bone, and manure for thousands of years i.e. approximately 10-1,000 times longer than residence times of most soil organic matter. The effect of biochar obtained from the wood biomass and other organic amendments (peat, compost) on soil thermal properties is presented in this paper. The results were compared with wetland soils of different organic matter content. The measurements of the thermal properties at various water contents were performed after incubation, under laboratory conditions using KD2Pro, Decagon Devices. The measured data were compared with predictions made using Usowicz statistical-physical model (Usowicz et al., 2006) for biochar, mineral soil and soil with addition of biochar at various water contents and bulk densities. The model operates statistically by probability of occurrence of contacts between particular fractional compounds. It combines physical properties, specific to particular compounds, into one apparent conductance specific to the mixture. The results revealed that addition of the biochar and other organic amendments into the soil caused considerable reduction of the thermal conductivity and diffusivity. The mineral soil showed the highest thermal conductivity and diffusivity that decreased in soil with addition of biochar and pure biochar. The reduction of both properties was mostly due to decrease in both particle density and bulk density. Both biochar and the organic amendments addition resulted in a decrease of the heat capacity of the mixtures in dry state and considerable increase in wet state. The lowest and highest reduction in the thermal conductivity with decreasing water content was obtained for pure biochar and mineral soil, respectively. The thermal diffusivity had a characteristic maximum at higher bulk densities and lower water contents. The wetland soil higher in organic matter content exhibit smaller temporal variation of the thermal properties compared to soils lower in organic matter content in response to changes of water content. The statistical-physical model was found to be useful for satisfactory predicting thermal properties of the soil with addition of biochar and organic amendments. Usowicz B. et al., 2006. Thermal conductivity modelling of terrestrial soil media - A comparative study. Planetary and Space Science 54, 1086-1095.

Usowicz, Boguslaw; Lukowski, Mateusz; Lipiec, Jerzy

2014-05-01

367

Biochemical properties of soils of undisturbed and disturbed mangrove forests of South Andaman (India)  

Microsoft Academic Search

Studies on soil quality of mangrove forests would be of immense use in minimizing soil degradation and in adopting strategies for soil management at degraded sites. Among the various parameters of soil quality, biological and biochemical soil properties are very sensitive to environmental stress and provide rapid and accurate estimates on changes in quality of soils subjected to degradation. In

R. Dinesh; S. G. Chaudhuri; A. N. Ganeshamurthy; S. C. Pramanik

2004-01-01

368

Geoestatistical analysis of soil properties in the South of Alicante: soil salinity.  

NASA Astrophysics Data System (ADS)

The southern coast of Alicante province (southeast of Spain) was largely occupied by a large lagoon until the eighteenth century when drainage infrastructures were built to turn much of the wetlands into irrigated farmlands. This area has a semiarid Mediterranean climate and the shortage of sufficient quality water for irrigation is a serious problem for agriculture and wetland maintenance. This study analyzes the spatial distribution of soil properties and their relationship with land-covers by the use of geostatistics and geographical information systems (GIS) as a tool for land-reclamation and management. A field campaign was conducted and 98 soil samples were collected and spatially referenced with a GPS. Soils of the study area are Calcic Fluvisols according to the World Reference Base for Soil Resources (WRB, 2006). Soil samples were air dried at room temperature and sieve at 2mm (soil fraction to be analysed). Four soil properties were analysed: 1) electrical conductivity (EC) (1:5 w/v water extraction), 2) pH, 3) equivalent carbonates (Porta et al., 1986), and 4) soil organic matter (SOM) by wet chemical oxidation (Walkley and Black, 1934) with potassium dichromate oxidation (Nelson and Sommers, 1982). Geostatistics was used to model the spatial distribution of soil properties. The convex hull of soil samples was used to delimit the area to map. Semivariograms were applied to study the spatial pattern of the four soil properties and ordinary Kriging was used to predict their spatial distribution. Descriptive statistics (mean ± standard deviation) showed that in general terms the soils studied was moderately saline (2.44 ± 0.32 dS×m-1), with a basic pH (8.22 ± 0.32), low soil organic matter content (1.41 ± 0.37 %) and abundant equivalent carbonates (46.1 ± 4.3 %). Electrical conductivity, pH and SOM properties were significantly correlated according with the Pearson bivariate correlation test (with P4 dS×m-1) or non-saline (EC

Melendez-Pastor, I.; Ayguadé, H.; Lag, A.; Navarro-Pedreño, J.; Gomez, I.

2010-05-01

369

Soil Properties, Nutrient Dynamics, and Soil Enzyme Activities Associated with Garlic Stalk Decomposition under Various Conditions  

PubMed Central

The garlic stalk is a byproduct of garlic production and normally abandoned or burned, both of which cause environmental pollution. It is therefore appropriate to determine the conditions of efficient decomposition, and equally appropriate to determine the impact of this decomposition on soil properties. In this study, the soil properties, enzyme activities and nutrient dynamics associated with the decomposition of garlic stalk at different temperatures, concentrations and durations were investigated. Stalk decomposition significantly increased the values of soil pH and electrical conductivity. In addition, total nitrogen and organic carbon concentration were significantly increased by decomposing stalks at 40°C, with a 5?100 ratio and for 10 or 60 days. The highest activities of sucrase, urease and alkaline phosphatase in soil were detected when stalk decomposition was performed at the lowest temperature (10°C), highest concentration (5?100), and shortest duration (10 or 20 days). The evidence presented here suggests that garlic stalk decomposition improves the quality of soil by altering the value of soil pH and electrical conductivity and by changing nutrient dynamics and soil enzyme activity, compared to the soil decomposition without garlic stalks. PMID:23226411

Han, Xu; Cheng, Zhihui; Meng, Huanwen

2012-01-01

370

Spatial and temporal variability of soil temperature, moisture and surface soil properties  

NASA Technical Reports Server (NTRS)

The overall objectives of this research were to: (l) Relate in-situ measured soil-water content and temperature profiles to remotely sensed surface soil-water and temperature conditions; to model simultaneous heat and water movement for spatially and temporally changing soil conditions; (2) Determine the spatial and temporal variability of surface soil properties affecting emissivity, reflectance, and material and energy flux across the soil surface. This will include physical, chemical, and mineralogical characteristics of primary soil components and aggregate systems; and (3) Develop surface soil classes of naturally occurring and distributed soil property assemblages and group classes to be tested with respect to water content, emissivity and reflectivity. This document is a report of studies conducted during the period funded by NASA grants. The project was designed to be conducted over a five year period. Since funding was discontinued after three years, some of the research started was not completed. Additional publications are planned whenever funding can be obtained to finalize data analysis for both the arid and humid locations.

Hajek, B. F.; Dane, J. H.

1993-01-01

371

Critical Zone Soil Properties effects on Soil Water Storage and Flux  

NASA Astrophysics Data System (ADS)

Soil properties control a wide range of hydrologic processes including recharge to regional aquifers. Soil water must pass through the critical zone to contribute to ground water recharge. Deep percolation (DP) from catchments is considered to be an estimate of mountain block recharge to regional aquifers. DP is also an important term in water mass balance studies, which attempt to estimate hydrologic states and fluxes in watersheds with fractured or transmissive bedrock. Few studies estimate the magnitude of this water balance term and it is often considered negligible. The objective of this study is to estimate the timing and magnitude of DP in the 0.015 km2 Tree Line experimental catchment (TL) from the 2011 water year. The catchment, which is located within the Dry Creek Experimental Watershed, Boise, ID, contains thin sandy soil over fractured granitic bedrock. We introduce modeling methods that focus on achieving a high degree of agreement between measured and modeled catchment storage. A distributed physically-based snow energy balance model is loosely coupled to a capacitance-based soil moisture model to estimate soil storage. Measured and calculated soil model parameters, including field capacity, saturated soil moisture content, and plant extraction limits, control the flux of water through the critical zone. Variability in soil storage and soil water fluxes through the critical zone is driven by soil properties. Parameters describing a leaf area index time series are calibrated to minimize the difference between measured and modeled soil dry down in the spring. DP is estimated to be 126 mm from Dec. 13, 2010 to June 30, 2011, which is 18% of the precipitation measured during that time. Rain-on-snow events are estimated to contribute 79 mm, which is 11% of precipitation or 63% of the calculated DP.

Kormos, P. R.; McNamara, J. P.; Seyfried, M. S.; Marks, D. G.; Flores, A. N.; Marshall, H.; Williams, C. J.

2012-12-01

372

Soil Properties Affecting the Reductive Capacity of Volcanic Ash Soils in Korea  

NASA Astrophysics Data System (ADS)

Volcanic ash soils or Andisols have distinct chemical and mineralogical properties. The unique chemical properties of Andisols are due to their Al-rich elemental composition, the highly reactive nature of their colloidal fractions, and their large surface area. The soils that developed from volcanic ash on Jeju Island, Korea, were classified as typical Andisols. The soils had an acidic pH, high water content, high organic matter, and clay-silty texture. The crystalline minerals in the samples were mainly ferromagnesian minerals, such as olivine and pyroxene, and iron oxides, such as magnetite and hematite derived from basaltic materials. A large amount of gibbsite was found in the subsurface horizon as a secondary product of the migration of excess Al. In addition, we found that considerable amounts of poorly ordered minerals like allophane and ferrihydrite were present in the Jeju soils. The SiO2 contents were lower than those of other soil orders, while the Al2O3 and Fe2O3 contents were higher. These results reflect some of the important chemical properties of Andisols. The chromium (VI/III) redox couple was used in the reductive capacity measurement. The mean reductive capacity of the Jeju soils was 6.53 mg/L reduced Cr(VI), which is 5.1 times higher than that of non-volcanic ash soils from inland Korea. The reductive capacity of the inland soils was correlated with the total carbon content. Such a high capacity for the reduction of soluble Cr(VI) must also be due to the relatively high carbon contents of the Jeju soils. Nevertheless, despite having 20 times higher total carbon contents, there was no correlation between the reductive capacity of the Jeju soils and the carbon content. These results imply that the reductive capacity of Jeju soils is not only controlled by the carbon content, but is also affected by other soil properties. Correlations of the reductive capacity with major elements showed that Al and Fe were closely connected to the reductive capacity of Jeju soils. In addition to the carbon content, other factors controlling the reductive capacity of Jeju soils may have a close relationship with the properties of andic soils, which contain considerable amounts of allophane and ferrihydrite. Andic soils offer distinct advantages regarding a high reductive capacity for Cr(VI), such as a very large surface area and unique adsorption characteristics. The adsorption of anions by Andisols results from chemisorption on `active' Al and Fe occurring in various forms, such as allophane, organometallic complexes, and ferrihydrite. In addition, since Andisols have a predominantly positive surface charge at soil pH, the soils can retain mobile anions, such as phosphate, nitrate, and chromate. The positive net charge is derived from the large amount of organic C and allophane. Therefore, the high reactive capacity of the Jeju soils suggests that the combined effects of a large number of electron donors, such as organic matter and Fe(II), and the adsorption characteristics of Andisols are complex and should be considered simultaneously when estimating the reductive capacity of andic soils.

Chon, C.; Ahn, J.; Kim, K.; Park, K.

2008-12-01

373

Assimilation of cosmic-ray neutron counts for updating of soil moisture and soil properties with application to irrigation scheduling  

NASA Astrophysics Data System (ADS)

The soil moisture is a good indicator of water stress during the irrigation scheduling. The cosmic-ray probes can measure the soil moisture at an intermediate scale through the interaction between the land surface neutron counts and soil moisture profile. This study investigated the assimilation of neutron measurements by a cosmic-ray probe for updating root zone soil moisture as well as soil properties (sand fraction, clay fraction and organic matter density) in Community Land Model (CLM) using the Local Ensemble Transform Kalman Filter (LETKF) for the real time optimal scheduling of irrigation. In order to map the soil moisture into measured neutron counts, the new COSMIC model is used as the non-linear measurement operator. The background uncertainties in CLM forecast were described by the uncertain model forcings and soil properties in the assimilation. Two groups of synthetic scenarios were studied for the optimization of real-time irrigation scheduling for fields of citrus trees: for the first group of scenarios soil texture was systematically finer with more clay and less sand than in the reference ('Wet bias') whereas for the second group of scenarios soil texture was coarser with less clay and more sand than in reality ('Dry bias'). The irrigation requirements were calculated based on the water deficit method using as input updated soil moisture contents after assimilation of neutron counts. For each of these two groups of scenarios seven scenarios, in which different combinations of ensemble weather forecast, data assimilation, soil properties optimization, were defined to estimate the irrigation requirement. Results show that the joint soil moisture and soil properties updating results overall in the best estimation of soil moisture, actual evapotranspiration and irrigation requirement. The characterization of soil moisture and soil properties can be improved after assimilation of cosmic-ray neutron counts. The biased soil properties result in wrong irrigation requirement. If soil parameters are also updated, the sensible and latent heat flux characterization is improved for biased soil properties.

Han, Xujun; Hendricks Franssen, Harrie-Jan; Ángel Jiménez Bello, Miguel; Rosolem, Rafael; Bogena, Heye; Martínez Alzamora, Fernando; Chanzy, André; Vereecken, Harry

2014-05-01

374

Elastic Properties of Compacted Clay Soils by Laser Ultrasonics  

NASA Astrophysics Data System (ADS)

To evaluate the effect of the excitation frequency on the dynamic properties of soils, the elastic modulus , shear modulus , and Poisson’s ratio for three Mexican compacted clayey soils were determined using two techniques: laser ultrasonic and resonant column (RC) tests. For the first, the parameters were determined by measurements of the P- and S-waves at ultrasonic frequencies and variations of the height of the cylindrical soil specimens and for the second one, a harmonic excitation between 5 Hz and 7 Hz was applied. Large variations in the elastic parameters through an ultrasonic axial scanning of the soil specimens were observed; this reveals the heterogeneity of these materials, while a decrease of the sample aspect ratio mainly affects the determination of Poisson’s ratio. The ultrasonic data were integrated with those from RC data to obtain a shear modulus profile covering both high and low frequencies. The interpolation on whether the data are either linear or not is an indication of the viscoelastic behavior of the compacted clayey soils. The specimens were: (a) clay from Texcoco Valley, (b) clay from Mexico Valley, and (c) granular soils from the Parota. Experimental determination of the mechanical properties of soils is very important because soil constitutive models are traditionally calibrated from global boundary measurements taken from laboratory soil specimens. The most difficult parameter to obtain is the Poisson’s ratio, as well as the shear modulus, which is a fundamental parameter for establishing the soil response under low amplitude vibrations and it is extremely important to foundation design.

Navarrete, M.; Godínez, F. A.; Villagrán-Muniz, M.

2013-09-01