Sample records for hydraulic properties soil

  1. UNSODA: UNSATURATED SOIL HYDRAULIC PROPERTY DATABASE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Initially released in 1996, the UNSODA database contains unsaturated soil hydraulic properties (water retention, hydraulic conductivity, soil water diffusivity) and auxiliary data (particle-size distribution, bulk density, organic matter content, etc.) for more than 800 soils. With the recent launc...

  2. BOREAS HYD-1 Soil Hydraulic Properties

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

    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).

  3. Microbial effect on soil hydraulic properties

    NASA Astrophysics Data System (ADS)

    Furman, Alex; Rosenzweig, Ravid; Volk, Elazar; Rosenkranz, Hella; Iden, Sascha; Durner, Wolfgang

    2014-05-01

    Although largely ignored, the soil contains large amount of biofilms (attached microbes) that can affect many processes. While biochemical processes are studied, biophysical processes receive only little attention. Biofilms may occupy some of the pore space, and by that affect the soil hydraulic properties. This effect on unsaturated soils, however, was not intensively studied. In this research we directly measure the hydraulic properties, namely the soil's unsaturated hydraulic conductivity function and retention curve, for soils containing real biofilm. To do that we inoculate soil with biofilm-forming bacteria and incubate it with sufficient amounts of nutrient until biofilm is formed. The hydraulic properties of the incubated soil are then measured using several techniques, including multi-step outflow and evaporation method. The longer measurements (evaporation method) are conducted under refrigeration conditions to minimize microbial activity during the experiment. The results show a clear effect of the biofilm, where the biofilm-affected soil (sandy loam in our case) behaves like a much finer soil. This qualitatively makes sense as the biofilm generates an effective pore size distribution that is characterized by smaller pores. However, the effect is much more complex and needs to be studied carefully considering (for example) dual porosity models. We compare our preliminary results with other experiments, including flow-through column experiments and experiments with biofilm analogues. Clearly a better understanding of the way microbial activity alters the hydraulic properties may help designing more efficient bioremediation, irrigation, and other soil-related processes.

  4. Scaling hydraulic properties of a macroporous soil Binayak P. Mohanty

    E-print Network

    Mohanty, Binayak P.

    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

  5. Soil Texture Triangle: Hydraulic Properties Calculator

    NSDL National Science Digital Library

    Saxton, Keith E., 1937-

    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. .

  6. Empirical equations for some soil hydraulic properties

    Microsoft Academic Search

    Roger B. Clapp; George M. Hornberger

    1978-01-01

    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.

  7. Use of remotely sensed soil moisture to determine soil hydraulic properties

    Microsoft Academic Search

    Walter Rawls; Michael Cosh; Thomas Jackson; Attila Nemes

    2004-01-01

    Laboratory and field methods for determining soil hydraulic properties are time consuming and expensive. An alternative approach is to use pedotransfer functions which predict various soil hydraulic properties based on more readily available physical properties. Pedotransfer functions have been developed that operate with various levels of information. Greater available information yields more reliable estimates of any particular hydraulic property. Because

  8. Implication of hydraulic properties of bioremediated diesel-contaminated soil.

    PubMed

    Hyun, Seunghun; Ahn, Mi-Youn; Zimmerman, Andrew R; Kim, Minhee; Kim, Jeong-Gyu

    2008-04-01

    The hydraulic properties, such as hydraulic conductivity and water retention, of aged diesel-contaminated and bioremediated soils were examined and implications of the hydraulic properties for assessing bioremediation performance of soils were proposed. Bioremediation of diesel-contaminated soil was performed over 80 d using three treatments; (I) no nutrient added, column-packed soil, (II) nutrient added, column-packed soil, and (III) nutrient added, loosen soil. Diesel reduction in treatment I soil (control soil) was negligible while treatment III showed the greatest extent of diesel biodegradation. All treatments showed greatest rates of diesel biodegradation during the first 20 d, followed by a much retarded biodegradation rate in the remaining incubation period. Reduction of the degradation rate due to entrained diesel within inaccessible soil pores was hypothesized and tested by measuring the hydraulic properties of two column-packed soils (treatments I and II). The hydraulic conductivity of treatment II soil (nutrient added) was consistently above that of treatment I soil (no nutrient added) at pressure heads between 0 and 15 cm. In addition, the water retention of treatment II soil was greater at pressure heads <100 cm (equivalent to pore size of >30 microm), suggesting that biodegradative removal of hydrocarbons results in enhanced wettability of larger soil pores. However, water retention was not significantly different for control and biodegraded soils at pressure heads >100 cm, where smaller size soil pores were responsible for the water retention, indicating that diesel remained in smaller soil pores (e.g., <30 microm). Both incubation kinetics and hydraulic measurements suggest that hydrocarbons located in small pores with limited microbe accessibility may be recalcitrant to bioremediation. PMID:18321559

  9. 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...

  10. 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...

  11. Estimation of soil hydraulic properties with microwave techniques

    NASA Technical Reports Server (NTRS)

    Oneill, P. E.; Gurney, R. J.; Camillo, P. J.

    1985-01-01

    Useful quantitative information about soil properties may be obtained by calibrating energy and moisture balance models with remotely sensed data. A soil physics model solves heat and moisture flux equations in the soil profile and is driven by the surface energy balance. Model generated surface temperature and soil moisture and temperature profiles are then used in a microwave emission model to predict the soil brightness temperature. The model hydraulic parameters are varied until the predicted temperatures agree with the remotely sensed values. This method is used to estimate values for saturated hydraulic conductivity, saturated matrix potential, and a soil texture parameter. The conductivity agreed well with a value measured with an infiltration ring and the other parameters agreed with values in the literature.

  12. Upscaling of soil hydraulic properties for steady state evaporation and infiltration

    E-print Network

    Mohanty, Binayak P.

    Upscaling of soil hydraulic properties for steady state evaporation and infiltration Jianting Zhu September 2002. [1] Estimation of effective/average soil hydraulic properties for large land areas and guidelines for upscaling soil hydraulic properties in an areally heterogeneous field. In this study, we

  13. 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...

  14. Soil hydraulic properties of sphagnum moss and peat

    NASA Astrophysics Data System (ADS)

    Weber, Tobias K. D.; Iden, Sascha C.; Scharnagl, Benedikt; Durner, Wolfgang

    2015-04-01

    The moisture state of the vadose zone (acrotelm) of ombrotrophic peatlands decisively determines whether carbon is contained in soil organic matter or released to the atmosphere. As the pore space is variably saturated with water throughout the year, oxygen diffusion, heat, and solute transport and thus the redox state are a function of water content over time. For prediction purposes, the hydrological processes must be epitomised in computer models which establish a link between the terrestrial water cycle and the carbon cycle. This requires a proper representation of effective soil hydraulic properties which are a mandatory input to the Richards equation, the standard model for variably-saturated flow processes in porous media. By applying the Richards equation to peatlands, one assumes that the acrotelm can be conceptualised as a rigid porous material. To test this approximation and select the most adequate set of soil hydraulic property functions, we conducted a series of specifically designed laboratory evaporation experiments on sphagnum moss and decomposed sphagnum peat. Sampling was carried out in five centimeter depth increments of an ombrotrophic bog profile in the Harz mountains. We selected sphagnum moss as it is a predominant plant species colonising bogs of the Boreal. Inverse modelling was used to test the adequacy of different parameterizations of soil hydraulic property functions. We used pressure head data measured by two tensiometers in the objective function to identify soil hydraulic properties. The Richards equation was used as process model. We critically assess the applicability of the van Genuchten/Mualem model, which finds frequent application in peatland hydrology, and discuss alternatives which account for (1) multimodal pore size distributions, (2) physical plausibility towards the dry end, (3) capillary and non-capillary storage and flow, and (4) isothermal flow of water vapour. Finally, our results indicate that applying the Richards equation to water flow under evaporation conditions to sphagnum moss and sphagnum peat is a feasible approximation.

  15. The EMSL Hydraulic Properties Apparatus: A Fully Automated Tool for Hydraulic Conductivity and Soil Moisture Retention Determinations

    Microsoft Academic Search

    T. W. Wietsma; M. Oostrom; M. A. Covert; M. J. Fayer

    2006-01-01

    Knowledge of hydraulic properties, such as hydraulic conductivity and soil moisture retention, is crucial for understanding flow and contaminant transport in the subsurface. Hydraulic properties are often important input parameters for numerical simulation of flow and transport. Unfortunately, acquisition of these properties is usually time consuming and costly because of the manual labor associated with the currently available laboratory techniques.

  16. The influence of soil hydraulic properties on bare soil evaporation dynamics

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    Evaporation from bare soil is an important component of the global water cycle and the energy balance of the earth's surface. Forecasting bare soil evaporation requires knowledge of physical soil properties like thermal and hydraulic conductivity, heat and water capacity, and the water-content dependency of the albedo. The focus of this contribution is to analyze the sensitivity of soil evaporation dynamics with respect to physical soil properties. A coupled numerical model of water, vapor, and heat flow in soil considering the surface energy balance and temperature effects on the transport coefficients is used for the analysis. Particular attention is devoted to the influence of soil hydraulic properties on the duration of stage-one evaporation and evaporation rates during stage-two. We illustrate the importance of an adequate parameterization of soil hydraulic properties which should account for water sorption in dry soil, water flow in completely and incompletely-filled pores, and vapor diffusion. A comparison with data from evaporation experiments in the laboratory under different atmospheric forcings provides the link between models and reality. This confrontation unveils that the use of classic parametrizations of soil hydraulic properties leads to a bias in the description of experimental data and model predictions.

  17. Impacts of Evaporation from Saline Soils on Soil Hydraulic Properties and Water Fluxes

    NASA Astrophysics Data System (ADS)

    Fierro, V.; Hernandez, M. F.; Braud, I.; Cristi Matte, F.; Hausner, M. B.; Suarez, F. I.; Munoz, J.

    2013-12-01

    Saline soils are common in arid zones, where evaporation from shallow groundwater is generally the major component of the water balance. Thus, accurate quantification of soil water evaporation is crucial to improve water resource management in these regions. Evaporation from saline soils is a complex process that couples the movement of salts, heat, liquid water and water vapor. Precipitation/dissolution reactions can alter the soil structure and modify flow paths. The impact of evaporation from shallow groundwater on soil properties and water fluxes poses a major hydrologic challenge that remains to be answered. As a preliminary approach to consider these effects, we used the SiSPAT model (Simple Soil Plant Atmospheric Transfer) to represent the movement of liquid water and water vapor in a saline soil column subjected to two groundwater levels under nonisothermal conditions. To parameterize the model, we determined the hydraulic properties of the soil before performing the soil column experiments. When the SiSPAT model was run using uniform and constant hydraulic properties, it was unable to predict the moisture and thermal profiles, or the cumulative evaporation. This inability to reproduce the observed data is most likely due to alterations of the soil structure as a result of precipitation/dissolution reactions. When the soil hydraulic properties were allowed to vary in space, the model reproduced the experimental data successfully, suggesting that the structure of the initially homogeneous soil column was modified. It is thus necessary to incorporate salt precipitation to correctly simulate evaporation in saline soils.

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

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

    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.

  19. Development and use of a database of hydraulic properties of European soils

    Microsoft Academic Search

    J. H. M. Wösten; A Lilly; A Nemes; C. Le Bas

    1999-01-01

    Many environmental studies on the protection of European soil and water resources make use of soil water simulation models. A major obstacle to the wider application of these models is the lack of easily accessible and representative soil hydraulic properties. In order to overcome this apparent lack of data, a project was initiated to bring together the available hydraulic data

  20. 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...

  1. Water infiltration and hydraulic conductivity in sandy cambisols: impacts of forest transformation on soil hydrological properties

    Microsoft Academic Search

    Oliver Bens; Niels Arne Wahl; Holger Fischer; Reinhard F. Hüttl

    2007-01-01

    Soil hydrological properties like infiltration capacity and hydraulic conductivity have important consequences for hydrological\\u000a properties of soils in river catchments and for flood risk prevention. They are dynamic properties due to varying land use\\u000a management practices. The objective of this study was to characterize the variation of infiltration capacity, hydraulic conductivity\\u000a and soil organoprofile development on forest sites with comparable

  2. Biofilm effect on hydraulic properties of unsaturated soils: experimental study and data analysis

    NASA Astrophysics Data System (ADS)

    Rosenzweig, Ravid; Volk, Elazar; Furman, Alex; Iden, Sascha; Durner, Wolfgang

    2015-04-01

    While it is well known that biofilm in saturated systems can cause significant reduction of the hydraulic conductivity, very limited attention has been given to the hydraulic properties under unsaturated conditions. Following preliminary experiments with a biofilm proxy and pore-network analysis, we use here direct measurements of soil hydraulic properties in substrates with real biofilms to investigate and quantify the biofilm effect on hydraulic properties of unsaturated soils, namely hydraulic conductivity function and retention curve. We show that biofilms can significantly alter the soil hydraulic properties under unsaturated conditions. Measurements of the soil's unsaturated hydraulic conductivity function and water retention curve were performed by using the multi-step outflow and evaporation methods. The measurements with a longer duration (evaporation method) were conducted under refrigeration conditions to minimize microbial activity during the experiment. Data were analyzed by the standard simplified evaporation method and by inverse numerical simulation, using a flexible, but time-invariant, model of hydraulic properties. First results show that the hydraulic properties of the biofilm-affected soils differ from those of the clean soils. Those differences depend on the biofilm amount, growing conditions and substrate concentrations.

  3. Hydraulic and mechanical properties of soil aggregates under organic and conventional soil management

    NASA Astrophysics Data System (ADS)

    Wójciga, A.; Ku?, J.; Turski, M.; Lipiec, J.

    2009-04-01

    Variation in hydraulic and mechanical properties of soil aggregates is an important factor affecting water storage and infiltration because the large inter-aggregate pores are dewatered first and the transport of water and solutes is influenced by the properties of the individual aggregates and contacts between them. A high mechanical stability of soil aggregates is fundamental for the maintenance of proper tilth and provides stable traction for farm implements, but limit root growth inside aggregates. The aggregate properties are largely influenced by soil management practices. Our objective was to compare the effects of organic and conventional soil management on hydraulic and mechanical properties of soil aggregates. Experimental fields subjected to long-term organic (14 years) and conventional managements were located on loamy soil at the Institute of Soil Science and Plant Cultivation - National Research Institute in Pulawy, Poland. Soil samples were collected from two soil depths (0-10 cm and 10-20 cm). After air-drying, two size fractions of soil aggregates (15-20 and 30-35 mm) were manually selected and kept in the dried state in a dessicator in order to provide the same boundary conditions. Following properties of the aggregates were determined: porosity (%) using standard wax method, cumulative infiltration Q (mm3 s-1) and sorptivity S (mm s -1/2) of water and ethanol using a tube with a sponge inserted at the tip, wettability (by comparison of sorptivity of water and ethanol) using repellency index R, crushing strength q (MPa) using strength testing device (Zwick/Roell) and calculated by Dexter's formula. All properties were determined in 15 replicates for each treatment, aggregates size and depth. Organic management decreased porosity of soil aggregates and ethanol infiltration. All aggregates revealed rather limited wettability (high repellency index). In most cases the aggregate wettability was lower under conventional than organic soil management. Crushing strength was higher for aggregates from organic managed field, especially for 30-35 mm aggregates.

  4. Field and laboratory estimates of pore size properties and hydraulic characteristics for subarctic organic soils

    Microsoft Academic Search

    Sean K. Carey; William L. Quinton; Neil T. Goeller

    2007-01-01

    Characterizing active and water-conducting porosity in organic soils in both saturated and unsaturated zones is required for models of water and solute transport. There is a limitation, largely due to lack of data, on the hydraulic properties of unsaturated organic soils in permafrost regions, and in particular, the relationship between hydraulic conductivity and pressure head. Additionally, there is uncertainty as

  5. Effects of Native Forest Restoration on Soil Hydraulic Properties, Auwahi, Maui

    NASA Astrophysics Data System (ADS)

    Perkins, K. S.; Nimmo, J. R.; Medeiros, A.

    2012-12-01

    Over historic time Hawai'i's dryland forests have been largely replaced by grasslands for grazing livestock; less than 10% of original dryland forest habitat remains. The reestablishment of native ecosystems on land severely degraded by long-term alternative use requires reversal of the impacts of erosion, organic-matter loss, and soil structural damage on soil hydraulic properties. These reforestation efforts depend on restoring soil ecological function, including soil hydraulic properties. We hypothesized that reforestation can measurably change soil hydraulic properties over restoration timescales. At a site on the island of Maui (Hawai'i, USA), we measured infiltration rate (Kfs), hydrophobicity, and abundance of preferential flow channels in a deforested grassland and in an adjacent exclosure where active reforestation has been going on for fourteen years. Results from field experiments support the hypothesis that reforestation at the Auwahi site has significantly altered plant-relevant soil hydraulic properties.

  6. 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...

  7. Impact of alpine meadow degradation on soil hydraulic properties over the Qinghai-Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Zeng, Chen; Zhang, Fan

    2015-04-01

    Alpine meadow is one of widespread vegetation types of the Qinghai-Tibetan Plateau. It is undergoing degradation under the background of global climate change, human activities and overgrazing. Soil moisture is important to alpine meadow ecology for its water and energy transfer processes, therefore soil hydraulic properties become key parameters for local eco-hydrological processes studies. However, little research focus on the changes and it's mechanisms of soil hydraulic properties during the degradation processes. In this study, soil basic and hydraulic properties at 0-10 cm and 40-50 cm soil layer depths under different degraded alpine meadow were analyzed. Pearson correlations were adopted to study the relationships among the investigated factors and principal component analysis was performed to identify the dominant factor. Results show that with increasing degree of degradation, soil sand content increased while soil saturated hydraulic conductivity (Ks) as well as soil clay content, soil porosity decreased in the 0-10 cm soil layers, and organic matter and root gravimetric density decreased in both the 0-10 cm and 40-50 cm soil layers. For soil unsaturated hydraulic conductivity, it reduced more slowly with decreasing pressure head under degraded conditions than non-degraded conditions. However, soil moisture showed no significant changes with increasing degradation. Soil Ks was significantly correlated (P = 0.01) with bulk density, soil porosity, soil organic matter and root gravimetric density. Among these, soil porosity is the dominant factor explaining about 90% of the variability in total infiltration flow. Under non-degraded conditions, the infiltration flow principally depended on the presence of macropores. With increasing degree of degradation, soil macropores quickly changed to mesopores or micropores. The proportion of total infiltration flow through macropores and mesopores significantly decreased with the most substantial decrease observed for the macropores in the 0-10 cm soil layer. The substantial decrease of macropores caused a cut in soil moisture and hydraulic conductivity.

  8. Scaling the flood regime with the soil hydraulic properties of the catchment

    NASA Astrophysics Data System (ADS)

    Peña Rojas, Luis Eduardo; Francés García, Félix; Barrios Peña, Miguel

    2015-04-01

    The spatial land cover distribution and soil type affect the hydraulic properties of soils, facilitating or retarding the infiltration rate and the response of a catchment during flooding events. This research analyzes: 1) the effect of land cover use in different time periods as a source of annual maximum flood records nonstationarity; 2) the scalability of the relationship between soil hydraulic properties of the catchment (initial abstractions, upper soil capillary storage and vertical and horizontal hydraulic conductivity) and the flood regime. The study was conducted in Combeima River basin in Colombia - South America and it was modelled the changes in the land uses registered in 1991, 2000, 2002 and 2007, using distributed hydrological modelling and nonparametric tests. The results showed that changes in land use affect hydraulic properties of soil and it has influence on the magnitude of flood peaks. What is a new finding is that this behavior is scalable with the soil hydraulic properties of the catchment flood moments have a simple scaling behavior and the peaks flow increases with higher values of capillary soil storage, whereas higher values, the peaks decreased. Finally it was applied Generalized Extreme Values and it was found scalable behavior in the parameters of the probability distribution function. The results allowed us to find a relationship between soil hydraulic properties and the behavior of flood regime in the basin studied.

  9. 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...

  10. 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...

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

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

    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.

  12. A modified hood infiltrometer to estimate the soil hydraulic properties from transient water flow measurements

    NASA Astrophysics Data System (ADS)

    Moret-Fernández, David; Latorrre, Borja; Peña, Carolina; González-Cebollada, Cesar

    2015-04-01

    In-situ measurements of soil hydraulic properties on cover soil surfaces are of paramount importance in many agronomic or hydrological researches. The hydraulic properties can be estimated form the cumulative infiltration curve measured with tension infiltrometers. Transient water flow analysis, which means shorter experiments, facilitates its use for in situ field application. This paper presents a portable and modified design of the hood infiltrometer, the hat infiltrometer (HI), which applied on covered soil surfaces, allows estimating the soil hydraulic properties from the measured transient cumulative infiltration curve. The HI consists of a water-supply reservoir jointed to a hat base placed on the soil surface. The base of the hat is closed by a sticks plus plasticine ring system. The HI was tested on two different soils at saturated conditions, and the estimated soprtivity (S) and hydraulic conductivity (K) were compared to the corresponding values obtained with a disc infiltrometer (DI). An additional field experiment was performed to compare the hydraulic properties measured with HI on a bare and a plant-covered soil. Results demonstrated that this design allows hermetically closing the base of the hat without soils surface disturbing. No significant differences between the K and S values estimated with DI and the HI were observed. The S values measured with HI on the covers soil were significantly higher than that measured on the adjacent bare soil. These results indicate that HI can be a viable alternative to estimate the soil hydraulic properties of cover soil surfaces from the measured transient infiltration curve.

  13. Impact of land management on soil structure and soil hydraulic properties

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

    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).

  14. The EMSL Hydraulic Properties Apparatus: A Fully Automated Tool for Hydraulic Conductivity and Soil Moisture Retention Determinations

    NASA Astrophysics Data System (ADS)

    Wietsma, T. W.; Oostrom, M.; Covert, M. A.; Fayer, M. J.

    2006-12-01

    Knowledge of hydraulic properties, such as hydraulic conductivity and soil moisture retention, is crucial for understanding flow and contaminant transport in the subsurface. Hydraulic properties are often important input parameters for numerical simulation of flow and transport. Unfortunately, acquisition of these properties is usually time consuming and costly because of the manual labor associated with the currently available laboratory techniques. Another drawback of standard techniques is that different packings or cores are used to determine different properties, which might result in inconsistent data sets. Lately, there has been increased interest in automating laboratory techniques to reduce analysis time and improve data consistency. The newly designed fully automated Hydraulic Properties Apparatus (HPA), located in EMSL's Subsurface Flow and Transport Experimental Laboratory, provides enhanced capabilities. The HPA is unique in that it can determine a consistent set of hydraulic properties for a single packing or core using multiple techniques (i.e., falling- head, constant-head, constant flux, multistep, and soil moisture retention relations). This paper demonstrates the new apparatus and presents data sets for standard laboratory Accusand and a Hanford Site porous media.

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

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

    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.

  16. 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 ...

  17. Numerical experiments on the sensitivity of runoff generation to the spatial variation of soil hydraulic properties

    NASA Astrophysics Data System (ADS)

    Herbst, Michael; Diekkrüger, Bernd; Vanderborght, Jan

    2006-07-01

    Spatially distributed soil hydraulic properties are required for distributed hydrological modelling. These soil hydraulic properties are known to vary significantly in space, and considering the non-linearity of runoff generation, the question arises how the spatial variation of soil hydraulic parameters affects the continuous runoff modelling for a micro-scale catchment. This was analysed by applying a three-dimensional hydrological model to the 28.6 ha 'Berrensiefen' catchment, Germany, for a simulation period of one year. The model was based on an observed distribution of soil hydraulic properties, which were assumed to be layered in vertical and to vary continuously in horizontal direction, and validated for total runoff. Numerical experiments with five spatial distributions of soil hydraulic parameters derived from the observed spatial distribution, which was supposed to be the 'true' underlying spatial variation, were carried out. These five spatial concepts were: choropleth map, spatially homogeneous case, random distribution, stochastic simulation and conditional stochastic simulation. The comparative modelling revealed a significant sensitivity of runoff generation towards the spatial variation of soil hydraulic properties. The comparison of the hydrograph of surface and macropore runoff to the initial model runs exhibited the highest root mean square error with 1.3 mm h -1 for the homogeneous case. Further we detected, that the frequency distribution of soil hydraulic properties played an important role for the reproduction of runoff amounts. But also the spatial topology (deterministic spatial variation) was relevant for an adequate description of runoff generation. Conditional stochastic simulation is seen as a promising approach, because it preserved both, the frequency distribution and the deterministic variation.

  18. The Comparison of Predicted and Measured Hydraulic Conductivities of Soils having Different Physical Properties

    NASA Astrophysics Data System (ADS)

    Zengin, Enes; Abiddin Erguler, Zeynal; Karaku?, Hüseyin

    2015-04-01

    Hydraulic conductivity is one of the most important parameter of earth science related studies such as engineering geology, soil physics, agriculture etc. In order to estimate the ability of soils to transport fluid through particles, field and laboratory tests have been performed since last decades of 19th century. Constant and falling head tests are widely used to directly measure hydraulic conductivity values in laboratory conditions for soils having different particle size distributions. The determination of hydraulic conductivity of soils by performing these methods are time consuming processes and also requires undisturbed samples to reflect in-situ natural condition. Considering these limitations, numerous approaches have been proposed to practically estimate hydraulic conductivity of soils by utilizing empirical equations based on simple physical and index properties such as grain size distribution curves related parameters, porosity, void ratio, etc. Many previous studies show that the hydraulic conductivity values calculated by empirical equations deviate more than two order magnitude than the measured hydraulic conductivity values obtained from convenient permeability tests. In order to investigate the main controlling parameters on hydraulic conductivity of soils, a comprehensive research program was carried out on some disturbed and undisturbed soil samples collected from different locations in Turkey. The hydraulic conductivity values of samples were determined as changing between 10-6 and 10-9 m/s by using falling head tests. In addition to these tests, basic soil properties such as natural water content, Atterberg limits, specific gravity and grain size analyses of these samples were also defined to be used as an input parameters of empirical equations for prediction hydraulic conductivity values. In addition, data from previous studies were also used for the aim of this study. The measured hydraulic conductivity values were correlated with all physical and index properties of soils by using regression analyses. Furthermore, the results belong to falling head tests were compared with the predicted values obtained from the most commonly utilized empirical equations suggested in previous studies. As a result of this comparison, it can be concluded that the difference between direct measurement and empirically calculated hydraulic conductivity values reaches beyond acceptable limits.

  19. Effect of biofilm on soil hydraulic properties: laboratory studies using xanthan as surrogate

    NASA Astrophysics Data System (ADS)

    Rosenkranz, H.; Iden, S. C.; Durner, W.

    2012-04-01

    Many soil bacteria produce extracellular polymeric substances (EPS) in which they are embedded while residing in the porous matrix. EPS are often attached as a biofilm to both the bacteria cell and the soil particles. As a consequence, their influence on water flow through variably saturated porous media often cannot be neglected. While the influence of attached microbial biomass and EPS on saturated water flow has been studied extensively, its investigation for unsaturated flow in soils has found significantly less attention. The objective of this study was the quantification of the effect of biofilms on the unsaturated soil hydraulic properties. We determined the soil water retention and unsaturated hydraulic conductivity functions of biofilm-affected soils by using xanthan as an EPS surrogate. Evaporation experiments were conducted on two sandy soil materials. The amount of added xanthan was varied in 6 stages from zero to 0.25 %. Additional measurements of soil water retention using the dewpoint method closed the remaining gap from the evaporation method to air-dryness. The experimental data were evaluated by the simplified evaporation method of Schindler. The results show that the unsaturated hydraulic conductivity is reduced markedly by added xanthan and the shape of the soil water retention curve is alterated significantly for all stages of xanthan addition. The reduction in hydraulic conductivity is high enough to fully suppress stage-one evaporation for xanthan-sand mixtures. The water-holding capacity of the xanthan and the alteration of the effective pore size distribution explain these results.

  20. Estimation of soil hydraulic properties using proximal spectral reflectance in visible, near-infrared, and shortwave-infrared (VIS–NIR–SWIR) region

    Microsoft Academic Search

    Priyabrata Santra; Rabi Narayan Sahoo; Bhabani Sankar Das; Ravindra Nath Samal; Ajit Kumar Pattanaik; Vinod Kumar Gupta

    2009-01-01

    Characterization of soil hydraulic properties is an important step for assessing soil water regime in agricultural fields. Because direct measurement of soil hydraulic properties at multiple locations is costly and time-consuming, pedotransfer functions (PTF) are conveniently used to estimate these properties from easily measurable basic soil properties. Over the last two decades, several studies have demonstrated that basic soil properties

  1. Integrated assessment of space, time, and management-related variability of soil hydraulic properties

    SciTech Connect

    Es, H.M. van; Ogden, C.B.; Hill, R.L.; Schindelbeck, R.R.; Tsegaye, T.

    1999-12-01

    Computer-based models that simulate soil hydrologic processes and their impacts on crop growth and contaminant transport depend on accurate characterization of soil hydraulic properties. Soil hydraulic properties have numerous sources of variability related to spatial, temporal, and management-related processes. Soil type is considered to be the dominant source of variability, and parameterization is typically based on soil survey databases. This study evaluated the relative significance of other sources of variability: spatial and temporal at multiple scales, and management-related factors. Identical field experiments were conducted for 3 yr. at two sites in New York on clay loam and silt loam soils, and at two sites in Maryland on silt loam and sandy loam soils, all involving replicated plots with plow-till and no-till treatments. Infiltrability was determined from 2054 measurements using parameters, and Campbell's a and b parameters were determined based on water-retention data from 875 soil cores. Variance component analysis showed that differences among the sites were the most important source of variability for a (coefficient of variation, CV = 44%) and b (CV = 23%). Tillage practices were the most important source of variability for infiltrability (CV = 10%). For all properties, temporal variability was more significant than field-scale spatial variability. Temporal and tillage effects were more significant for the medium- and fine-textured soils, and correlated to initial soil water conditions. The parameterization of soil hydraulic properties solely based on soil type may not be appropriate for agricultural lands since soil-management factors are more significant. Sampling procedures should give adequate recognition to soil-management and temporal processes at significant sources of variability to avoid biased results.

  2. Impact of alpine meadow degradation on soil hydraulic properties over the Qinghai-Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Zeng, Chen; Zhang, Fan; Wang, Quanjiu; Chen, Yingying; Joswiak, Daniel R.

    2013-01-01

    SummaryAlpine meadow soil is an important ecosystem component of the Qinghai-Tibetan Plateau. However, the alpine meadow soil is undergoing serious degradation mainly due to global climate change, overgrazing, human activities and rodents. In this paper, spatial sequencing was chosen over time succession sequencing to study the changes of soil hydraulic properties under different degrees of alpine meadow degradation. Soil saturated hydraulic conductivity (Ks) and Gardner ? both at the surface and at 40-50 cm depth were investigated in the field using tension infiltrometers. Soil physical and chemical properties, together with the root index at 0-10 cm and 40-50 cm soil layer depths were also analyzed. Pearson correlations were adopted to study the relationships among the investigated factors and principal component analysis was performed to identify the dominant factor. Results show that with increasing degree of degradation, soil sand content increased while soil Ks and Gardner ? as well as soil clay content, soil porosity decreased in the 0-10 cm soil layers, and organic matter and root gravimetric density decreased in both the 0-10 cm and 40-50 cm soil layers. However, soil moisture showed no significant changes with increasing degradation. With decreasing pressure head, soil unsaturated hydraulic conductivity reduced more slowly under degraded conditions than non-degraded conditions. Soil Ks and Gardner ? were significantly correlated (P = 0.01) with bulk density, soil porosity, soil organic matter and root gravimetric density. Among these, soil porosity is the dominant factor explaining about 90% of the variability in total infiltration flow. Under non-degraded conditions, the infiltration flow principally depended on the presence of macropores. With increasing degree of degradation, soil macropores quickly changed to mesopores or micropores. The proportion of total infiltration flow through macropores and mesopores significantly decreased with the most substantial decrease observed for the macropores in the 0-10 cm soil layer. The substantial decrease of macropores caused a cut in soil moisture and hydraulic conductivity. This study improves the understanding and prediction of alpine meadow soil and ecosystem changes and provides guidelines for improving water flow modeling under the background of global climate change over the Qinghai-Tibetan Plateau and similar regions.

  3. Using Tension Infiltrometry to Assess the Effect of Subsoil Compaction on Soil Hydraulic Properties

    NASA Astrophysics Data System (ADS)

    Schwen, Andreas; Carrick, Sam; Buchan, Graeme

    2010-05-01

    Soil compaction is a major cause of soil degradation all over the world. The related changes in soil physical parameters are of growing importance in agricultural production. To understand fully the effects of different degrees of subsoil compaction on the growth and yield of arable plants requires knowledge of changes in both the soil hydraulic conductivity function, and in the soil water retention curve. In the present study measurements of the hydraulic properties were obtained on an arable field in the Canterbury Plains, South Island, New Zealand. The soil is classified as Templeton silt loam. The uppermost 15 cm of the soil were removed and replaced following five contrasting subsoil treatments. The subsoil was either cultivated (loosened), untreated, or compacted using a heavy roller with three different steps of compaction. Five randomised replications of each subsoil treatment were established. At each of the 25 plots, infiltration measurements were obtained at two depths: on the soil surface and within the compacted soil layer at 18 cm depth. Tension infiltrometry was used, as this method allows the precise and in situ determination of the hydraulic properties at near-saturated conditions. These conditions coincide with flow activation in the macro porosity of the soil. Thus, this method is also suitable to determine the amount and distribution of macro pores, as well as preferential flow paths in soils. Only a few studies have measured the near-saturated parts of the retention and conductivity curves of Templeton soils. The supply tensions were -15 cm, -10 cm, -4 cm, -1 cm, and 0 cm. Undisturbed soil samples were taken with steel cores before each measurement in the vicinity of each measurement site, enabling measurement of the initial and saturated water contents in the laboratory. Post-measurement samples were also taken directly below the infiltration disc to measure the final water content. The cumulative infiltration together with the initial and final water contents were used to inversely determine the parameters of a suitable soil water retention model using the Hydrus 2D/3D software package. A statistical analysis will reveal any differences in the soil hydraulic properties that can be traced back to soil compaction. We expect that compaction of (sub-)soils leads to a significant decrease in macro porosity and hence a decrease of saturated hydraulic conductivity.

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

    USGS Publications Warehouse

    Perkins, Kimberlie S.; Nimmo, John R.; Medeiros, Arthur C.

    2012-01-01

    Over historic time Hawai'i's dryland forests have been largely replaced by grasslands for grazing livestock. On-going efforts have been undertaken to restore dryland forests to bring back native species and reduce erosion. The reestablishment of native ecosystems on land severely degraded by long-term alternative use requires reversal of the impacts of erosion, organic-matter loss, and soil structural damage on soil hydraulic properties. This issue is perhaps especially critical in dryland forests where the soil must facilitate native plants' optimal use of limited water. These reforestation efforts depend on restoring soil ecological function, including soil hydraulic properties. We hypothesized that reforestation can measurably change soil hydraulic properties over restoration timescales. At a site on the island of Maui (Hawai'i, USA), we measured infiltration capacity, hydrophobicity, and abundance of preferential flow channels in a deforested grassland and in an adjacent area where active reforestation has been going on for fourteen years. Compared to the nearby deforested rangeland, mean field-saturated hydraulic conductivity in the newly restored forest measured by 55 infiltrometer tests was greater by a factor of 2.0. Hydrophobicity on an 8-point scale increased from average category 6.0 to 6.9. A 4-point empirical categorization of preferentiality in subsurface wetting patterns increased from an average 1.3 in grasslands to 2.6 in the restored forest. All of these changes act to distribute infiltrated water faster and deeper, as appropriate for native plant needs. This study indicates that vegetation restoration can lead to ecohydrologically important changes in soil hydraulic properties over decadal time scales.

  5. 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...

  6. Spatial Prediction of Hydraulic Zones from Soil Properties and Secondary Data Using Factorial Kriging Analysis

    NASA Astrophysics Data System (ADS)

    Bevington, James; Morari, Francesco; Scudiero, Elia; Teatini, Pietro; Vellidis, George

    2015-04-01

    The development of pedotransfer functions (PTF) is an important topic in soil science research because there is a critical need for incorporation of vadose zone phenomena into large scale climate models. Soil measurements are inherently spatially dependent and therefore application of geospatial statistics provides an avenue for estimating soil properties. The aim of this study is to define management zones based on soil hydraulic properties. Samples were collected from 50 locations at 4 depths in a 20.8ha field located in the Po River delta in Italy. Water retention curves (WRC) and unsaturated hydraulic conductivity curves (UHC) and were determined via inversion of measurements taken using the Wind (Dane and Topp, 1994) method. This region is in known to have paleo-channel structures and highly heterogeneous soils. Factorial kriging analysis (FKA) was applied to hydraulic parameters in one data set and soil physical properties in another data set at 4 depths. The mapped principal components (PCs) were used in a fuzzy-c means algorithm to define zones of like properties. To examine the physical significance of these zones, curve parameters and hydraulic curves were investigated. Zones were able to distinguish between ?_s(saturated water content), n (shape parameter) and ? (inverse of air entry) while ?r (residual water content) and Ks (saturated conductivity) were not statistically different between the groups. For curve comparisons, WRC were found to be significantly different between zones at all tensions while effective saturation curves (Se) differ for the majority of tensions (except at 28cm), but UHC did not differ. The spatial relevance of the zones was examined by overlaying hydraulic zones with zones defined using the FKA and fuzzy-c means approach from soil physical properties such as texture and bulk density. The hydraulic zones overlaid with areal accuracy ranging from 46.66% to 92.41%. As there is much similarity between these sets of zones, there is a potential to predict hydraulic zones from zones defined from soil physical properties. This work illustrates the potential to incorporate geospatial statistics in the development of pedotransfer functions.

  7. 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 ...

  8. Measuring Particle Size Distribution using Laser Diffraction: Implications for Predicting Soil Hydraulic Properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methods to predict soil hydraulic properties frequently require information on the particle size distribution (PSD). The objectives of this study were to investigate various protocols for rapidly measuring PSD using the laser diffraction technique, compare the obtained PSDs with those determined usi...

  9. Dual Extended Kalman Filter in retrieving effective soil hydraulic properties by surface soil moisture assimilation

    NASA Astrophysics Data System (ADS)

    Medina, H.; Chirico, G. B.; Romano, N.

    2009-04-01

    Retrieving soil moisture profiles from surface data assimilation in soil hydrological models has to cope with the uncertainty in the soil hydraulic parameters. Some studies have proved that, in case of poorly identified soil hydraulic parameters, model predictions may even be worse than model estimates without data assimilation. Therefore, the sequential estimation of both states and parameters from noisy signals is a fundamental prerequisite for suitably addressing the underlying challenge. The dual Extended Kalman Filter (EKF) has proved, at least theoretically, to be an efficient technique for generating approximate maximum-likelihood estimates of both states and parameters of a discrete-time nonlinear dynamic system. The objective of this work is to evaluate the accuracy of the dual EKF for retrieving soil moisture profiles and soil hydraulic parameters simultaneously by the assimilation of moisture-related surface data in a one-dimensional simulation hydrologic model. Parameters under scrutiny were the saturated hydraulic conductivity, Ks, as well as parameters "?" and "n" describing the shape of the van Genuchten water retention relation. The present study provides useful insights on the implementation of the dual EKF into computer models applied to the vadose zone hydrology. The sensitivity of dual EKF results to several computational aspects is evaluated with numerical experiments. An effective procedure is proposed for getting efficient predictions even for high errors of the initial state and parameter values. The parameter convergence is affected more than the depth of the observations within the soil profile than by the initial state and parameter values.

  10. Assessing the influence of the rhizosphere on soil hydraulic properties using X-ray computed tomography and numerical modelling

    PubMed Central

    Daly, Keith R.; Mooney, Sacha J.; Bennett, Malcolm J.; Crout, Neil M. J.; Roose, Tiina; Tracy, Saoirse R.

    2015-01-01

    Understanding the dynamics of water distribution in soil is crucial for enhancing our knowledge of managing soil and water resources. The application of X-ray computed tomography (CT) to the plant and soil sciences is now well established. However, few studies have utilized the technique for visualizing water in soil pore spaces. Here this method is utilized to visualize the water in soil in situ and in three-dimensions at successive reductive matric potentials in bulk and rhizosphere soil. The measurements are combined with numerical modelling to determine the unsaturated hydraulic conductivity, providing a complete picture of the hydraulic properties of the soil. The technique was performed on soil cores that were sampled adjacent to established roots (rhizosphere soil) and from soil that had not been influenced by roots (bulk soil). A water release curve was obtained for the different soil types using measurements of their pore geometries derived from CT imaging and verified using conventional methods, such as pressure plates. The water, soil, and air phases from the images were segmented and quantified using image analysis. The water release characteristics obtained for the contrasting soils showed clear differences in hydraulic properties between rhizosphere and bulk soil, especially in clay soil. The data suggest that soils influenced by roots (rhizosphere soil) are less porous due to increased aggregation when compared with bulk soil. The information and insights obtained on the hydraulic properties of rhizosphere and bulk soil will enhance our understanding of rhizosphere biophysics and improve current water uptake models. PMID:25740922

  11. Assessing the influence of the rhizosphere on soil hydraulic properties using X-ray computed tomography and numerical modelling.

    PubMed

    Daly, Keith R; Mooney, Sacha J; Bennett, Malcolm J; Crout, Neil M J; Roose, Tiina; Tracy, Saoirse R

    2015-04-01

    Understanding the dynamics of water distribution in soil is crucial for enhancing our knowledge of managing soil and water resources. The application of X-ray computed tomography (CT) to the plant and soil sciences is now well established. However, few studies have utilized the technique for visualizing water in soil pore spaces. Here this method is utilized to visualize the water in soil in situ and in three-dimensions at successive reductive matric potentials in bulk and rhizosphere soil. The measurements are combined with numerical modelling to determine the unsaturated hydraulic conductivity, providing a complete picture of the hydraulic properties of the soil. The technique was performed on soil cores that were sampled adjacent to established roots (rhizosphere soil) and from soil that had not been influenced by roots (bulk soil). A water release curve was obtained for the different soil types using measurements of their pore geometries derived from CT imaging and verified using conventional methods, such as pressure plates. The water, soil, and air phases from the images were segmented and quantified using image analysis. The water release characteristics obtained for the contrasting soils showed clear differences in hydraulic properties between rhizosphere and bulk soil, especially in clay soil. The data suggest that soils influenced by roots (rhizosphere soil) are less porous due to increased aggregation when compared with bulk soil. The information and insights obtained on the hydraulic properties of rhizosphere and bulk soil will enhance our understanding of rhizosphere biophysics and improve current water uptake models. PMID:25740922

  12. 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...

  13. Soil hydraulic properties estimate based on numerical analysis of disc infiltrometer three-dimensional infiltration curve

    NASA Astrophysics Data System (ADS)

    Latorre, Borja; Peña-Sancho, Carolina; Angulo-Jaramillo, Rafaël; Moret-Fernández, David

    2015-04-01

    Measurement of soil hydraulic properties is of paramount importance in fields such as agronomy, hydrology or soil science. Fundamented on the analysis of the Haverkamp et al. (1994) model, the aim of this paper is to explain a technique to estimate the soil hydraulic properties (sorptivity, S, and hydraulic conductivity, K) from the full-time cumulative infiltration curves. The method (NSH) was validated by means of 12 synthetic infiltration curves generated with HYDRUS-3D from known soil hydraulic properties. The K values used to simulate the synthetic curves were compared to those estimated with the proposed method. A procedure to identify and remove the effect of the contact sand layer on the cumulative infiltration curve was also developed. A sensitivity analysis was performed using the water level measurement as uncertainty source. Finally, the procedure was evaluated using different infiltration times and data noise. Since a good correlation between the K used in HYDRUS-3D to model the infiltration curves and those estimated by the NSH method was obtained, (R2 =0.98), it can be concluded that this technique is robust enough to estimate the soil hydraulic conductivity from complete infiltration curves. The numerical procedure to detect and remove the influence of the contact sand layer on the K and S estimates seemed to be robust and efficient. An effect of the curve infiltration noise on the K estimate was observed, which uncertainty increased with increasing noise. Finally, the results showed that infiltration time was an important factor to estimate K. Lower values of K or smaller uncertainty needed longer infiltration times.

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

    NASA Astrophysics Data System (ADS)

    Wang, Tiejun

    2014-11-01

    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.

  15. Saturated hydraulic conductivity and soil water retention properties across a soil-slope transition

    E-print Network

    Mohanty, Binayak P.

    Binayak P. Mohanty U.S. Salinity Laboratory, Riverside, California Zak Mousli University of California Bay n at 30-cm depth; and (3) a higher nugget effect at 15-cm depth was evident for most soil hydraulic- teristic features of these factors are interlinked by landscape and plant-habitat evolution. Understanding

  16. Fire Induced Changes in Soil Structure: Implications for Soil Hydraulic Properties and Aeolian Suspension Potential in the Great Basin, USA

    NASA Astrophysics Data System (ADS)

    Shafer, D. S.; Dubois, D. W.; Chief, K.; Berli, M.; Miller, J. J.; Young, M.

    2009-12-01

    Most studies on post-fire effects lack a true comparison to pre-fire conditions. The Upper Gleason controlled burn in a Pinus monophylla/Juniperus Osteosperma (single-leaf pinyon pine/Utah juniper) and Artemisia sp. (sagebrush) transition zone in east central Nevada (elevation range 2183 to 2397 m) was used to test hypotheses on how fire-induced changes in soil structure affect soil hydraulic and aeolian suspension properties. The area to be burned had moderate subangular blocky soil structure. However, where other controlled burns had been done nearby, this structure had collapsed into a structureless soil, rich in fine particles. Prior to the fire, a plot within the area to be burned and a control plot were established where soil samples were collected for bulk density, total C, and total organic C analyses; and a multi-disc tension infiltrometer and an air permeameter were used to measure saturated hydraulic conductivity (Ks) and air permeability (ka). Water drop penetration time (WDPT) was measured for detection of hydrophobic conditions, and a portable wind tunnel (PI-SWERLTM) was used to measure wind shear required to induce aeolian transport of fine particles. For both the soil hydraulic and aeolian transport properties, measurements were made in both intercanopy and undercanopy microsites. Thermocouples were buried at 0.10 m depth for point measurements of near surface soil temperature during the fire. The 470 hectare burn was conducted on 12 August 2009. Post-fire samples and measurements of the same soil property parameters are being made at the burned plot as well as in the control area. WDPT tests conducted one-week after the fire indicated slight water repellency at intercanopy sites. The soils most susceptible to aeolian erosion were on undercanopy sites that burned. Hypotheses include that 1) the fire will alter soil structure, increasing soil bulk density, and decreasing soil hydraulic conductivity and air permeability, a set of conditions that would increase the potential for soil erosion by water; and 2) the loss of soil structure will disaggregate soil material that would be more prone to suspension by wind at lower wind velocities compared to pre-burn conditions. The Upper Gleason fire caused uneven breakdown of the subangular structure on the surface. Additional changes in soil structure (e.g., compaction) may occur following other post-fire events such as heavy precipitation (rain or snowfall).

  17. Estimation of soil hydraulic properties based on time-lapse Ground-Penetrating Radar (GPR) measurements

    NASA Astrophysics Data System (ADS)

    Jaumann, Stefan; Klenk, Patrick; Roth, Kurt

    2015-04-01

    Recent developments brought surface-based GPR measurements to a precision that make them useful for estimating soil hydraulic properties. For this study, we estimate Mualem-Brooks-Corey parameters for a layered subsurface material distribution employing the Levenberg-Marquardt inversion algorithm. The required measurement data were recorded at our artificial test site ASSESS, where we forced the hydraulic system with a fluctuating water table and observed the dynamic deformation of the capillary fringe with time-lapse GPR. Subsequently, these measurements were simulated based on a model comprising (i) the Richards equation describing the temporal evolution of the soil hydraulic system which was solved with MUPHI, (ii) the Complex Refractive Index Model (CRIM) serving as petrophysical relationship which links the soil hydraulic model to (iii) the electrodynamic model consisting of Maxwell's equations which are solved with MEEP. For the objective function of the optimization algorithm, both measured and simulated GPR data were evaluated with a semi-automated wavelet feature detection algorithm allowing to directly compare the travel time and amplitude of the GPR signal. In this presentation, we discuss the results of the inversion based on the inversion of GPR data and we also discuss how including Time Domain Reflectometry (TDR) measurement data influences the estimated parameters.

  18. Effective Hydraulic Properties Determined from Transient Unsaturated Flow in Anisotropic Soils

    SciTech Connect

    Ward, Andy L.; Zhang, Z. F.

    2007-11-01

    Hydraulic parameters including the pore connectivity/tortuosity tensor (L_i) were inversely estimated using the STOMP numerical simulator coupled with the parameter estimation code, UCODE. Results show that six of eight parameters required for a modified van Genuchten-Mualem model could be inversely estimated using water content measured during transient infiltration from a surface line source and approximated prior information. Soils showed evidence of saturation-dependent anisotropy that was well described with the connectivity tensor. Variability of the vertical saturated hydraulic conductivity was larger than the horizontal. The autocorrelation ranges for the horizonatal and vertical Ks; the inverse of the air-entry value, and the horizontal connectivity were between 2.4 and 4.6 m whereas the van Genuchten shape parameter, n, and saturated water content showed no autocorrelation. Accurate upscaling of hydraulic properties requires the correct assessment of the connectivity of facies.

  19. Microbially Induced Changes in Unsaturated Zone Hydraulic Properties During Soil Flushing Remediation Trails

    NASA Astrophysics Data System (ADS)

    Smith, J. E.; Badley, J. A.; Smith, J. M.; Bashir, R.

    2004-05-01

    Field trials were conducted to assess a cyclodextrin as a soil flushing remediation agent. During those trials, data collected with Time Domain Reflectometry (TDR), the Guelph Permeameter, and timed-application without-ponding showed significant and substantial changes in water holding capacity, field-saturated hydraulic conductivity, and infiltration rates respectively. The changes were large enough to limit the treatment period for the highest application rate plots. The changes were assumed to be due to bio-clogging. Subsequent experiments in one meter tall laboratory columns instrumented with TDR directly assessed the proportion of the observed hydraulic changes that could be attributed to microbial-induced changes versus abiotic effects. While small abiotic effects were observed in columns receiving treatments containing a biocide, large changes in hydraulic properties consistent with those observed in the field were attributable to enhanced microbial activity.

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

    USGS Publications Warehouse

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

    2009-01-01

    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.

  1. Modeling biofilm dynamics and hydraulic properties in variably saturated soils using a channel network model

    NASA Astrophysics Data System (ADS)

    Rosenzweig, Ravid; Furman, Alex; Dosoretz, Carlos; Shavit, Uri

    2014-07-01

    Biofilm effects on water flow in unsaturated environments have largely been ignored in the past. However, intensive engineered systems that involve elevated organic loads such as wastewater irrigation, effluent recharge, and bioremediation processes make understanding how biofilms affect flow highly important. In the current work, we present a channel-network model that incorporates water flow, substrate transport, and biofilm dynamics to simulate the alteration of soil hydraulic properties, namely water retention and conductivity. The change in hydraulic properties due to biofilm growth is not trivial and depends highly on the spatial distribution of the biofilm development. Our results indicate that the substrate mass transfer coefficient across the water-biofilm interface dominates the spatiotemporal distribution of biofilm. High mass transfer coefficients lead to uncontrolled biofilm growth close to the substrate source, resulting in preferential clogging of the soil. Low mass transfer coefficients, on the other hand, lead to a more uniform biofilm distribution. The first scenario leads to a dramatic reduction of the hydraulic conductivity with almost no change in water retention, whereas the second scenario has a smaller effect on conductivity but a larger influence on retention. The current modeling approach identifies key factors that still need to be studied and opens the way for simulation and optimization of processes involving significant biological activity in unsaturated soils.

  2. Topographical attributes to predict soil hydraulic properties along a hillslope transect

    NASA Astrophysics Data System (ADS)

    Leij, Feike J.; Romano, Nunzio; Palladino, Mario; Schaap, Marcel G.; Coppola, Antonio

    2004-02-01

    Basic soil properties have long been used to predict unsaturated soil hydraulic properties with pedotransfer function (PTFs). Implementation of such PTFs is usually not feasible for catchment-scale studies because of the experimental effort that would be required. On the other hand, topographical attributes are often readily available. This study therefore examines how well PTFs perform that use both basic soil properties and topographical attributes for a hillslope in Basilicata, Italy. Basic soil properties and hydraulic data were determined on soil samples taken at 50-m intervals along a 5-km hillslope transect. Topographical attributes were determined from a digital elevation model. Spearman coefficients showed that elevation (z) was positively correlated with organic carbon (OC) and silt contents (0.62 and 0.59, respectively) and negatively with bulk density (?b) and sand fraction (-0.34 and -0.37). Retention parameters were somewhat correlated with topographical attributes z, slope (?), aspect (cos?), and potential solar radiation. Water contents were correlated most strongly with elevation (coefficient between 0.38 and 0.48) and aspect during "wet" conditions. Artificial neural networks (ANNs) were developed for 21 different sets of predictors to estimate retention parameters, saturated hydraulic conductivity (Ks), and water contents at capillary heads h = 50 cm and 12 bar (103 cm). The prediction of retention parameters could be improved with 10% by including topography (RMSE = 0.0327 cm3 cm-3) using textural fractions, ?b, OC, z, and ? as predictors. Furthermore, OC became a better predictor when the PTF also used z as predictor. The water content at h = 50 cm could be predicted 26% more accurately (RMSE = 0.0231 cm3cm-3) using texture, ?b, OC, z, ?, and potential solar radiation as input. Predictions of ANNs with and without topographical attributes were most accurate in the wet range (0 < h < 250 cm). Semivariograms of the hydraulic parameters and their residuals showed that the ANNs could explain part of the (spatial) variability. The results of this study confirm the utility of topographical attributes such as z, ?, cos?, and potential solar radiation as predictors for PTFs when basic soil properties are available. A next step would be the use of topographical attributes when no or limited other predictors are available.

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

    NASA Astrophysics Data System (ADS)

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

    2005-12-01

    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.

  4. Estimating water and nitrate leaching in tree crops using inverse modelled plant and soil hydraulic properties

    NASA Astrophysics Data System (ADS)

    Couvreur, Valentin; Kandelous, Maziar; Mairesse, Harmony; Baram, Shahar; Moradi, Ahmad; Pope, Katrin; Hopmans, Jan

    2015-04-01

    Groundwater quality is specifically vulnerable in irrigated agricultural lands in California and many other (semi-)arid regions of the world. The routine application of nitrogen fertilizers with irrigation water in California is likely responsible for the high nitrate concentrations in groundwater, underlying much of its main agricultural areas. To optimize irrigation/fertigation practices, it is essential that irrigation and fertilizers are applied at the optimal concentration, place, and time to ensure maximum root uptake and minimize leaching losses to the groundwater. The applied irrigation water and dissolved fertilizer, root nitrate and water uptake interact with soil and root properties in a complex manner that cannot easily be resolved. It is therefore that coupled experimental-modelling studies are required to allow for unravelling of the relevant complexities that result from typical variations of crop properties, soil texture and layering across farmer-managed fields. A combined field monitoring and modelling approach was developed to quantify from simple measurements the leaching of water and nitrate below the root zone. The monitored state variables are soil water content within the root zone, soil matric potential below the root zone, and nitrate concentration in the soil solution. Plant and soil properties of incremented complexity are optimized with the software HYDRUS in an inverse modelling scheme, which allows estimating leaching under constraint of hydraulic principles. Questions of optimal irrigation and fertilization timing can then be addressed using predictive results and global optimization algorithms.

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

    USGS Publications Warehouse

    Shakofsky, S.M.

    1995-01-01

    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.

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

    SciTech Connect

    Shakofsky, S.

    1995-03-01

    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 semiarid 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.

  7. May We Identify The Spatial Variability of Soil Hydraulic Properties Based On Measurements With

    Microsoft Academic Search

    E. Zehe; R. Becker; W. Schädel

    2002-01-01

    A dynamic system left without external disturbances, will always tend to a stable equilibrium state that is consistent with the internal physics. For natural soils such an equilibrium state is reached when the gradients of the total hydraulic potential tend to zero. This statement is still valid for heterogeneous soils, because the hydraulic po- tential is an intensive state variable

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

    NASA Technical Reports Server (NTRS)

    Eagleson, Peter S.; Jasinski, Michael F.

    1988-01-01

    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.

  9. Combining SEBAL model and NMCGA algorithm for the estimation of effective soil hydraulic properties

    NASA Astrophysics Data System (ADS)

    Shin, Y.; Mohanty, B. P.; Ines, A. M.

    2009-12-01

    Remote sensing data provide valuable information in many hydrological and meteological models. In this study, NMCGA developed by Ines and Mohanty (2008, Parameter Conditioning with a Noisy Monte Carlo Genetic Algorithm for Estimating Effective Soil Hydraulic properties from Space, Water Resources Research) is combined with the SEBAL model to integrate an ET component for quantifying the effective hydraulic properties using the pixel-based soil moisture and ET datasets. Three numerical experiments are conducted for different scenarios: 1) a free-draining homogeneous soil column using ET, SM and SM+ET, 2) a homogenous column under the SM and SM+ET conditions with a shallow water table depth of -100 cm, and 3) validation of the combined NMCGA-ET at different hydroclimatic field conditions. The results of Case 1 examined under hypothetical conditions (from the UNSODA database) suggest that the combined NMCGA-ET improves the optimized solutions (theta(h) and K(h)) better than those of NMCGA alone, although K(h) will have small uncertainties, and will respond well to (deep) soil moisture dynamics in the unsaturated zone. The results in Case 2 are evident in that an ET component contributes to the reduction of uncertainties inherent in a shallow water table. In Case 3, the application of the combined NMCGA-ET is evaluated at the Walnut Creek, Iowa and Brown, Illinois, sites. The correlation (R2) and MBE under the SM+ET condition are identified as better than those of only using the SM condition at all sites. However, the results at the Brown site using the direct soil moisture estimation method (neutron probe technique) are estimated to be better than those at the WC sites. Nevertheless, the results estimated at the WC sites correspond well with the pixel-based observed values of soil moisture as well (R2 > 0.77). From these findings, it is demonstrated that the combined NMCGA-ET performs better than the NMCGA for quantifying effective soil hydraulic properties based on inverse modeling and contributes to the reduction of uncertainties (+/-95PCI) due to within footprint heterogeneities.

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

    NASA Technical Reports Server (NTRS)

    Gutmann, Ethan D.; Small, Eric E.

    2007-01-01

    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.

  11. Comparison of three hydraulic property measurement methods

    Microsoft Academic Search

    Dirk Mallants; Diederik Jacques; Peng-Hsiang Tseng; Martinus Th. van Genuchten; Jan Feyen

    1997-01-01

    Hydraulic functions of soils may differ depending on the different measuring methods used. The performance of three different methods for measuring soil-hydraulic properties of a heterogeneous field were evaluated. The experiments were conducted using three different sizes of undisturbed soil cores collected systematically along a 31 m long transect of a well drained sandy loam soil having three soil horizons

  12. Estimation and analysis of soil hydraulic properties through infiltration experiments: test of BEST method

    Microsoft Academic Search

    X. Xu; G. Kiely; C. Lewis

    2009-01-01

    The BEST method (Beerkan Estimation of Soil Transfer parameters through infiltration experiments) appears promising and easy for field experiments of large scale to estimate not only the saturated hydraulic conductivity but also the water retention and hydraulic characteristics. However, few tests have been conducted to test it so far. This study involved BEST infiltration experiments in the field at three

  13. 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)

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

    2009-12-01

    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.

  14. Laboratory analysis of soil hydraulic properties of TA-49 soil samples. Volume I: Report summary

    SciTech Connect

    NONE

    1995-04-01

    The Hydrologic Testing Laboratory at Daniel B. Stephens & Associates, Inc. (DBS&A) has completed laboratory tests on TA-49 soil samples as specified by Mr. Daniel A. James and summarized in Table 1. Tables 2 through 12 give the results of the specified analyses. Raw laboratory data and graphical plots of data (where appropriate) are contained in Appendices A through K. Appendix L lists the methods used in these analyses. A detailed description of each method is available upon request. Thermal properties were calculated using methods reviewed by Campbell and covered in more detail in Appendix K. Typically, soil thermal conductivities are determined using empirical fitting parameters (five in this case), Some assumptions are also made in the equations used to reduce the raw data. In addition to the requested thermal property measurements, calculated values are also presented as the best available internal check on data quality. For both thermal conductivities and specific heats, calculated and measured values are consistent and the functions often cross. Interestingly, measured thermal conductivities tend to be higher than calculated thermal conductivities around typically encountered in situ moisture contents ({plus_minus}5 percent). While we do not venture an explanation of the difference, sensitivity testing of any problem requiring nonisothermal modeling across this range is in order.

  15. Laboratory analysis of soil hydraulic properties of CDBM 2 and CDBM 3 samples

    SciTech Connect

    NONE

    1992-12-01

    Daniel B. Stephens & Associates, Inc. (DBS&A) was requested by Dr. Alan Stoker of Los Alamos National Laboratory to perform laboratory analysis for properties of CDBM 2 and CDBM 3 samples, as outlined in Subcontract No. 9-XTI-027EE-1. The scope of work included conducting tests for the following properties: Initial moisture content, dry bulk density, and calculated porosity; Saturated hydraulic conductivity; Moisture characteristics; Unsaturated hydraulic properties (calculated); and Transient outflow.

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

    NASA Technical Reports Server (NTRS)

    Eagleson, P. S.

    1985-01-01

    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.

  17. Using pedotransfer functions to estimate the van Genuchten-Mualem soil hydraulic properties: A review

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this paper, we review the use of the van Genuchten Mualem (VGM) model to parameterize the soil moisture retention characteristic (MRC) and the nsaturated hydraulic conductivity curve (HCC), as well as its use in developing pedotransfer functions (PFTs). Analysis of literature data showed that MRC...

  18. Unsaturated hydraulic conductivity function based on a soil fragmentation process

    E-print Network

    Tartakovsky, Daniel M.

    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

  19. 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

    Boyer, Edmond

    2003-01-01

    properties of peat soils 23 Hydrology and Earth System Sciences, 7(1), 23­32 (2003) © EGU An easily installable groundwater lysimeter to determine water balance components and hydraulic properties of peat soils.Schwaerzel@TU-Berlin.de Abstract A simple method for the installation of groundwater lysimeters in peat soils was developed which

  20. Determination of hydraulic properties of a tropical soil using inverse modeling

    NASA Astrophysics Data System (ADS)

    Sobotkova, Martina; Snehota, Michal; Ray, Chittaranjan; Dohnal, Michal

    2010-05-01

    Pesticides and other contaminants that have polluted ground water on the island of Oahu, Hawaii have passed through hundreds of meters of vadose zone. The sorption and degradation of these contaminants in soil affect the concentration reaching the ground water. An accurate description of contaminant mass arrival in ground water also depends on flow behavior of water through the vadose zone. The goal of this study was to examine the flow behavior of water and determine hydraulic parameters of an Oxisol using a laboratory infiltration-outflow experiment on two medium-sized undisturbed soil columns. The soil columns were collected from the B horizon of Wahiawa Oxisol from the Poamoho Experiment Station of the University of Hawaii located in center region of Oahu island, Hawaii, USA. Infiltration-outflow experiments were conducted using a semi-automatic set-up to determine the parameters of the water retention curve and hydraulic conductivity function of the soil. Water flow through the soil cores was simulated by numerical solution of the one-dimensional Richards equation representing a single-domain porous medium. Using measured soil hydraulic parameters, initial forward modeling was carried out and then the parameters were estimated by inverse modeling using various scenarios. A combination of manual optimization and inverse modeling produced a good fit between model outputs and measured data of water flux and pressure head. Water content for a given pressure from the retention curve measured directly on small soil samples were lower than that obtained through parameter optimization based on experiments on larger undisturbed soil samples. Laboratory experiments were conducted at the University of Hawaii in the framework of the project "Evaluation of the fate and transport of selected chemicals in Hawaii soils", Hawaii Department of Agriculture, 6/02-7/05. The work was also partially supported by research project No. 103/08/1552 under the Czech Science Foundation.

  1. Fire Induced Changes in Soil Structure: Implications for Soil Hydraulic Properties and Aeolian Suspension Potential in the Great Basin, USA

    Microsoft Academic Search

    D. S. Shafer; D. W. Dubois; K. Chief; M. Berli; J. J. Miller; M. Young

    2009-01-01

    Most studies on post-fire effects lack a true comparison to pre-fire conditions. The Upper Gleason controlled burn in a Pinus monophylla\\/Juniperus Osteosperma (single-leaf pinyon pine\\/Utah juniper) and Artemisia sp. (sagebrush) transition zone in east central Nevada (elevation range 2183 to 2397 m) was used to test hypotheses on how fire-induced changes in soil structure affect soil hydraulic and aeolian suspension

  2. Impact of spruce forest and grass vegetation cover on soil micromorphology and hydraulic properties of organic matter horizon

    Microsoft Academic Search

    Radka Kodešová; Lenka Pavl?; Vít Kodeš; Anna Žigová; Antonín Nikodem

    2007-01-01

    Two organic matter horizons developed under a spruce forest and grass vegetation were chosen to demonstrate the impact of\\u000a a different vegetation cover on the micromorphology, porous system and hydraulic properties of surface soils. Micromorphological\\u000a studies showed that the decomposed organic material in the organic matter horizon under the grass vegetation was more compact\\u000a compared to the decomposed organic material

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

    NASA Technical Reports Server (NTRS)

    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

    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.

  4. Uniqueness and stability analysis of hydrogeophysical inversion for time-lapse ground-penetrating radar estimates of shallow soil hydraulic properties

    Microsoft Academic Search

    Khan Zaib Jadoon; Evert Slob; Marnik Vanclooster; Harry Vereecken; Sébastien Lambot

    2008-01-01

    Precise measurement of soil hydraulic properties at field scales is one of the prerequisites to simulate subsurface flow and transport processes, which is crucial in many research and engineering areas. In our study, we numerically analyze uniqueness and stability for integrated hydrogeophysical inversion of time-lapse, off-ground ground-penetrating radar (GPR) data in estimating the unsaturated soil hydraulic properties. In the inversion,

  5. 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...

  6. Spatial variability of soil hydraulics and remotely sensed soil parameters

    NASA Technical Reports Server (NTRS)

    Lascano, R. J.; Van Bavel, C. H. M.

    1982-01-01

    The development of methods to correctly interpret remotely sensed information about soil moisture and soil temperature requires an understanding of water and energy flow in soil, because the signals originate from the surface, or from a shallow surface layer, but reflect processes in the entire profile. One formidable difficulty in this application of soil physics is the spatial heterogeneity of natural soils. Earlier work has suggested that the heterogeneity of soil hydraulic properties may be described by the frequency distribution of a single scale factor. The sensitivity of hydraulic and energetic processes to the variation of this scale factor is explored with a suitable numerical model. It is believed that such an analysis can help in deciding how accurately and extensively basic physical properties of field soils need to be known in order to interpret thermal or radar waveband signals. It appears that the saturated hydraulic conductivity needs to be known only to its order of magnitude, and that the required accuracy of the soil water retention function is about 0.02 volume fraction. Furthermore, the results may be helpful in deciding how the total scene or view field, as perceived through a sensor, is composed from the actual mosaic of transient soil properties, such as surface temperature or surface soil moisture. However, the latter proposition presupposes a random distribution of permanent properties, a condition that may not be met in many instances, and no solution of the problem is apparent.

  7. Selection of soil hydraulic properties in a land surface model using remotely-sensed soil moisture and surface temperature

    NASA Astrophysics Data System (ADS)

    Shellito, P. J.; Small, E. E.; Gutmann, E. D.

    2013-12-01

    Synoptic-scale weather is heavily influenced by latent and sensible heating from the land surface. The partitioning of available energy between these two fluxes as well as the distribution of moisture throughout the soil column is controlled by a unique set of soil hydraulic properties (SHPs) at every location. Weather prediction systems, which use coupled land surface and atmospheric models in their forecasts, must therefore be parameterized with estimates of SHPs. Currently, land surface models (LSMs) obtain SHP values by assuming a correlation exists between SHPs and the soil type, which the USDA maps in 12 classes. This method is spurious because texture is only one control of many that affects SHPs. Alternatively, SHPs can be obtained by calibrating them within the framework of an LSM. Because remotely-sensed data have the potential for continent-wide application, there is a critical need to understand their specific role in calibration efforts and the extent to which such calibrated SHPs can improve model simulations. This study focuses on SHP calibration with soil moisture content (SMC) and land surface temperature (Ts), data that are available from the SMOS and MODIS satellite missions, respectively. The scientific goals of this study are: (1) What is the model performance tradeoff between weighting SMC and Ts differently during the calibration process? (2) What can the tradeoff between calibration using in-situ and remotely-sensed SMC reveal about SHP scaling? (3) How are these relationships influenced by climatic regime and vegetation type? (4) To what extent can calibrated SHPs improve model performance over that of texture-based SHPs? Model calibrations are carried out within the framework of the Noah LSM using the Shuffled Complex Evolution Metropolis (SCEM-UA) algorithm in five different climatic regimes. At each site, a five-dimensional parameter space of SHPs is searched to find the location that minimizes the difference between observed and simulated SMC and Ts. The optimization weighting between SMC and Ts is varied in successive runs. The calibrated SHPs are validated at each site by comparing the simulated latent heat flux and runoff to those measured at a Fluxnet eddy covariance tower and stream gauge, respectively. Initial results indicate that the ideal weighting between SMC and Ts will depend on the vegetative cover and climate. SMC is a more valuable metric in wet, vegetated environments, and Ts is more useful in arid or semi-arid locations. Optimization on remotely-sensed SMC produces more accurate latent heat flux and runoff simulations than does optimization on in-situ SMC. Using calibrated SHPs instead of texture-based SHPs decreases the modeled latent heat flux error by at least one-third. Future research will focus on continent-wide SHP calibration, which may result in improved LSM simulations and more accurate weather and climate predictions.

  8. Bayesian inverse modeling of vadose zone hydraulic properties in a layered soil profile with data-driven likelihood function inference

    NASA Astrophysics Data System (ADS)

    Over, M. W.; Wollschlaeger, U.; Osorio-Murillo, C. A.; Ames, D. P.; Rubin, Y.

    2013-12-01

    Good estimates for water retention and hydraulic conductivity functions are essential for accurate modeling of the nonlinear water dynamics of unsaturated soils. Parametric mathematical models for these functions are utilized in numerical applications of vadose zone dynamics; therefore, characterization of the model parameters to represent in situ soil properties is the goal of many inversion or calibration techniques. A critical, statistical challenge of existing approaches is the subjective, user-definition of a likelihood function or objective function - a step known to introduce bias in the results. We present a methodology for Bayesian inversion where the likelihood function is inferred directly from the simulation data, which eliminates subjectivity. Additionally, our approach assumes that there is no one parameterization that is appropriate for soils, but rather that the parameters are randomly distributed. This introduces the familiar concept from groundwater hydrogeology of structural models into vadose zone applications, but without attempting to apply geostatistics, which is extremely difficult in unsaturated problems. We validate our robust statistical approach on field data obtained during a multi-layer, natural boundary condition experiment and compare with previous optimizations using the same data. Our confidence intervals for the water retention and hydraulic conductivity functions as well as joint posterior probability distributions of the Mualem-van Genuchten parameters compare well with the previous work. The entire analysis was carried out using the free, open-source MAD# software available at http://mad.codeplex.com/.

  9. Three-dimensional quantification of soil hydraulic properties using X-ray Computed Tomography and image-based modeling

    NASA Astrophysics Data System (ADS)

    Tracy, Saoirse R.; Daly, Keith R.; Sturrock, Craig J.; Crout, Neil M. J.; Mooney, Sacha J.; Roose, Tiina

    2015-02-01

    We demonstrate the application of a high-resolution X-ray Computed Tomography (CT) method to quantify water distribution in soil pores under successive reductive drying. We focus on the wet end of the water release characteristic (WRC) (0 to -75 kPa) to investigate changes in soil water distribution in contrasting soil textures (sand and clay) and structures (sieved and field structured) and to determine the impact of soil structure on hydraulic behavior. The 3-D structure of each soil was obtained from the CT images (at a 10 ?m resolution). Stokes equations for flow were solved computationally for each measured structure to estimate hydraulic conductivity. The simulated values obtained compared extremely well with the measured saturated hydraulic conductivity values. By considering different sample sizes we were able to identify the smallest possible representative sample size which is required to determine a globally valid hydraulic conductivity.

  10. Plant root-driven hydraulic redistribution, root nutrient uptake and carbon exudation interact with soil properties to generate rhizosphere resource hotspots that vary in space and time

    NASA Astrophysics Data System (ADS)

    Espeleta, J. F.; Neumann, R. B.; Cardon, Z. G.; Mayer, K. U.; Rastetter, E. B.

    2014-12-01

    Hydraulic redistribution (HR) of soil water by plants occurs in seasonally dry ecosystems worldwide. During drought, water flows from deep moist soil, through plant roots, into dry (often litter-rich) upper soil layers. Using modeling, we explored how physical transport processes driven by transpiration and hydraulic redistribution interact with root physiology (nutrient uptake and carbon exudation) and soil properties (soil texture and cation exchange) to influence nitrogen and carbon concentrations in the rhizosphere. At the single root scale, we modeled a 10-cm radial soil domain, and simulated solute transport, soil cation exchange, and root exudation and nutrient uptake under two water flow patterns: daytime transpiration without nighttime HR, and daytime transpiration with nighttime HR. During HR, water efflux flushed solutes away from the root, diluting the concentrations of key nutrients like nitrate. The transport of cations by transpiration in the day and their accumulation near the root led to competitive desorption of ammonium from soil further from the root and generation of hotspots of ammonium availability at night. HR influenced the spatial and temporal patterns of these hotspots and their intensity. They were also influenced by soil properties of texture and cation exchange capacity. This dynamic resource landscape caused by diel cycling between transpiration and hydraulic redistribution presents a stage for greater complexity of microbial interactions. We are currently embedding a microbial community and small food web into this rhizosphere model in order to explore how organisms responsible for nutrient and soil carbon cycling respond to these fluctuating resource regimes.

  11. 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)

    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

    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.

  12. Monitoring Soil Hydraulic and Thermal Properties using Coupled Inversion of Time-lapse Temperature and Electrical Resistance Data

    NASA Astrophysics Data System (ADS)

    Tran, A. P.; Dafflon, B.; Hubbard, S. S.; Kowalsky, M. B.; Tokunaga, T. K.; Faybishenko, B.; Long, P.

    2014-12-01

    Evaluation of spatiotemporal dynamics of heat transport and water flow in terrestrial environments is essential for understanding hydrological and biogeochemical processes. Electrical resistance tomography has been increasingly well used for monitoring subsurface hydrological processes and estimating soil hydraulic properties through coupled hydrogeophysical inversion. However, electrical resistivity depends on a variety of factors such as temperature, which may limit the accuracy of hydrogeophysical inversion. The main objective of this study is to develop a hydrogeophysical inversion framework to enable the incorporation of nonisothermal processes into the hydrogeophysical inversion procedure, and use of this procedure to investigate the effect of hydrological controls on biogeochemical cycles in terrestrial environments. We developed the coupled hydro-thermal-geophysical inversion approach, using the iTOUGH2 framework. In this framework, the heat transport and water flow are simultaneously modeled with TOUGH2 code, which effectively accounts for the multiphase, multi-component and nonisothermal flow in porous media. A flexible approach is used to incorporate petrophysical relationships and uncertainty to link soil moisture and temperature with the electrical resistivity. The developed approach was applied to both synthetic and field case studies. At the DOE subsurface biogeochemistry field site located near Rifle CO, seasonal snowmelt delivers a hydrological pulse to the system, which in turn influences the cycles of nitrogen, carbon and other critical elements. Using the new approach, we carried out numerical inversion of electrical resistance data collected along a 100 m transect at the Rifle site, and compared the results with field investigations of the soil, vadose zone, including the capillary fringe, and groundwater, as well as temperature and tensiometer measurements. Preliminary results show the importance of accounting for nonisothermal conditions to reliably interpret electrical resistance measurements and to determine hydraulic and thermal properties that influence biogeochemical cycles.

  13. 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...

  14. 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...

  15. A method for the determination of the hydraulic properties of soil from MODIS surface temperature for use in land-surface models

    Microsoft Academic Search

    Ethan D. Gutmann; Eric E. Small

    2010-01-01

    Soil hydraulic properties (SHPs) play an important role in land-surface models, but their spatial distribution is poorly known, and it is not feasible to make field measurements of SHPs everywhere they are needed. In addition, the scale SHPs are measured on (10 cm) is substantially smaller than the scale at which land-surface models are run (>1 km). As a result,

  16. Effects of long-term irrigation with treated wastewater on the hydraulic properties, and the water and air regime in the root zone of a clayey soil.

    NASA Astrophysics Data System (ADS)

    Assouline, Shmuel

    2013-04-01

    With increasing water scarcity, treated wastewater (TW) appears as an attractive alternative source of water for irrigation, especially in arid and semi-arid regions where freshwater is naturally scarce. However, it seems that long-term use of TW for irrigation of orchards planted on heavy soils cause to yield reduction and crop damages. In terms of water quality, TW are characterized by higher concentrations of sodium and dissolved organic content (DOC) that affect soil exchangeable sodium percentage (ESP) on one hand and soil wettability, on the other hand. The working hypothesis of this study is that long-term use of TW for irrigation of clayey soils causes significant changes in the soil hydraulic properties. Such changes might affect the water and air regime in the root zone, and the hydrological balance components at the field scale. High-resolution field sampling determined the spatial distribution of chloride, ESP and DOC below the dripper, revealing higher salinity and sodicity, lower hydraulic conductivity, and possible preferential flow pattern linked to wettability in WW-irrigated soils. Laboratory experiments involving infiltration, evaporation, and swelling pressure measurements provide quantitative estimates of the impact of TW for irrigation on the soil hydraulic properties. The upper soil layer of TW-irrigated plots is more affected by the impact of DOC on soil wettability, while the lower layers are more affected by the impact of the increased ESP on soil hydraulic conductivity. Continuous monitoring of oxygen concentration at 10, 20 and 30 cm depths in the root zone near the trees and at mid-distance between trees revealed that the air regime in the root zone is significantly affected by the TW use as a consequence for the effect on the water regime.

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

    Microsoft Academic Search

    Shakofsky

    1995-01-01

    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)

  18. Effect of Tillage on Soil Hydraulic Conductivity in Two Contrasting Soil Textures

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tillage profoundly affects soil physical and hydraulic properties. It is essential to select a tillage system that sustains the soil hydraulic properties required for successful growth of agricultural crops. We compared effects of conventional tillage (CT) and strip tillage (ST) systems on field-sat...

  19. Laboratory Hydraulic Testing in Unsaturated Soils

    Microsoft Academic Search

    Farimah Masrouri; Kátia V. Bicalho; Katsuyuki Kawai

    2008-01-01

    This paper synthesizes the state-of-the art of the various laboratory testing techniques presently available for measuring\\u000a the water hydraulic constitutive functions of unsaturated soils. Emphasis is on the laboratory testing techniques for measuring\\u000a the soil–water retention curves and the water hydraulic conductivity functions of unsaturated soils. The significant recent\\u000a advances in the investigation of the hydraulic behaviour of unsaturated swelling

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

    USGS Publications Warehouse

    Ebel, Brian A.; Nimmo, John R.

    2010-01-01

    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.

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

    SciTech Connect

    Ebel, Brian A.; Nimmo, John R.

    2009-12-29

    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.

  2. Soil hydraulic conductivity as affected by physical and chemical properties of effluents

    E-print Network

    Paris-Sud XI, Université de

    in Ksa, for both soils, whereas more than double this reduction was caused by unfiltered effluent. The results show that the main mechanism responsible for the immediate decrease in soil Ksa, upon effluent facteurs physico-chimiques qui peuvent provoquer une réduction de la conductivité hydraulique (Ksa,) des

  3. A Brazilian soil hydraulic database and field capacity analysis

    NASA Astrophysics Data System (ADS)

    Luiza Lima Ferreira, Ana; Van Dam, Jos Cornelis; de Jong van Lier, Quirijn

    2015-04-01

    Field Capacity (FC) is a widely-used concept by agricultural engineers, hydrologists and soil physicists to quantify the available soil water during growing seasons and the accessible soil water storage during intensive rainfall periods. In the field FC does depend on various environmental factors, including the soil hydraulic properties, rate of evapotranspiration, root density distribution, and groundwater level. Therefore world-wide different approaches are used to determine field capacity, based on both static and dynamic criteria. Dynamic criteria are usually related to the simulation of the soil internal drainage, until the percolation attains a negligible value. Recently Assouline and Or (2014) proposed a soil intrinsic characteristic length to determine the FC pressure head. This characteristic length is related to the loss of hydraulic continuity and is derived from the soil water retention function. In Brazil soil hydraulic properties were not yet organized in a database. Therefore we collected existing data of unsaturated soil hydraulic properties across Brazil, using available PhD thesis and scientific publications. This inquiry resulted in a soil sample data set of 106 horizons. We fitted the soil hydraulic parameters (?r, ?s, ?, n,g? and Ks)of the Mualem-Van Genuchten (1980) function to all soil samples. Next we derived FC values based on soil internal drainage and using the characteristic length according to Assouline and Or (2014). The internal drainage is analysed with the agrohydrological model SWAP (Kroes and van Dam, 2008). In the poster we will present the Brazilian soil hydraulic database and the derived FC values.

  4. Soil Hydraulic Characteristics of a Small Southwest Oregon Watershed Following

    E-print Network

    Standiford, Richard B.

    --------------------------------------------- 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

  5. Surface Soil Hydraulic and Biophysical Properties Across a Hillslope in the Ozark Highlands

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Heterogeneity of infiltration and subsurface redistribution of soil water can have a profound influence on plant growth and productivity as well as water quality. However, substantial uncertainty exists in assessing hydrologic impacts over multiple scales with complexity potentially compounded by mu...

  6. 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...

  7. Relationship between Anisotropy in Soil Hydraulic Conductivity and Saturation

    SciTech Connect

    Zhang, Z. Fred

    2014-01-01

    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.

  8. Development of hydraulic properties and nitrate turnover processes in minerotrophic fen soil on differnet scales

    NASA Astrophysics Data System (ADS)

    Kleimeier, Christian; Lennartz, Bernd

    2014-05-01

    Generally, it is recommended to remove the uppermost highly degraded peat layer from fens prior to rewetting to eliminate a potential source of organic pollutants for downstream water bodies. We investigated this material as a potential medium for denitrifying filters to further use the organic material. We are aiming to remove nitrate from tile drainage runoff at the outlet drainage dominated catchments to fullfill the requirements of the European Water Framework Directive. In a lysimeter scale long term mesocosm experiments we were aiming to reveal the peats behavior after disturbing and rewetting under constant flow conditions. Tracer experiments revealed a restructuring of the peat ending up at 20/80 percentage of mobile immobile pore volume. Additionally we observed the nitrate turnover. The turnover rate was determined by the hydraulic load. Absolute turnover rates were equal at lower and higher concentrations as well as flow rates, whereas the turnover reached higher percentages at lower concentrations. To further reveal the nitrate turnover processes flow through rector experiments were conducted in an anaerobic environment. We found that strongly reducing conditions can be created in peat even at the presence of nitrate. Thus we can conclude that the minerotrophic peat with its high iron and sulfur concentrations also enables autotrophic denitrification oxidizing iron and sulfur. While the conditions are favorable to re-reduce iron and sulfur,thus an electron shuttling system developed transporting electrons from the organic material as initial e- donor to nitrate as terminal e- acceptor.

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

    NASA Technical Reports Server (NTRS)

    Eagleson, Peter S.; Jasinski, Michael F.

    1988-01-01

    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.

  10. Soil Properties

    NSDL National Science Digital Library

    Carrie Davis Todd

    In order to introduce soil properties, students will determine the texture and color of a variety of local soils brought in by their classmates. Each student will describe their soil to the class, indicating where the soil came from and any interesting features regarding the site. Students will group the soils based on this little bit of knowledge and then re-evaluate their groupings after texture and color have been determined. This activity concludes with a discussion of regional soils and variations in soils.

  11. Soil Structure and Saturated Hydraulic Conductivity

    NASA Astrophysics Data System (ADS)

    Houskova, B.; Nagy, V.

    The role of soil structure on saturated hydraulic conductivity changes is studied in plough layers of texturally different soils. Three localities in western part of Slovakia in Zitny ostrov (Corn Island) were under investigation: locality Kalinkovo with light Calcaric Fluvisol (FAO 1970), Macov with medium heavy Calcari-mollic Fluvisol and Jurova with heavy Calcari-mollic Fluvisol. Soil structure was determined in dry as well as wet state and in size of macro and micro aggregates. Saturated hydraulic conductivity was measured by the help of double ring method. During the period of ring filling the soil surface was protected against aggregates damage by falling water drops. Spatial and temporal variability of studied parameters was evaluated. Cultivated crops were ensilage maize at medium heavy and heavy soil and colza at light soil. Textural composition of soil and actual water content at the beginning of measurement are one of major factor affecting aggregate stability and consequently also saturated hydraulic conductivity.

  12. 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...

  13. Effective hydraulic parameters for steady state vertical flow in heterogeneous soils

    E-print Network

    Mohanty, Binayak P.

    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

  14. Xylem Hydraulics and the SoilPlantAtmosphere Continuum: Opportunities and Unresolved Issues

    E-print Network

    Stiller, Volker

    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

  15. May 10, 2013 Determining Soil Hydraulic Conductivity

    E-print Network

    Fay, Noah

    Current methods used to quantify hydraulic conductivity require either lab testing of soil samples these methods have been considered a standard in hydrogeologic studies, they often disturb the soil, can cause compression of the soil samples, and only provide a specific point measurement which is not representative

  16. Soil hydraulic properties and their effect on surface and subsurface water transfer in a tropical rainforest catchment

    Microsoft Academic Search

    M. BONELL

    1981-01-01

    ABSTRACT This,paper,examines,spatial,and,temporal heterogeneity of the surface, subsurface and vertical drainage,components,within,and,between,three,sites,in a 25.7 ha tropical,rainforest,catchment. ,Our analysis indicates,that,saturation,overland,flow,depends,on the relationships,between,temporal,variations,in rainfall intensity, the upper soil store capacity, and the spatial variation,of saturated,hydraulic,conductivity,in the subsoil,below,20 cm. This,results,in saturation,overland flow occurring throughout storms on the upper slopes, but being confined to rainfall intensity peaks in the lower, incised,area,during,the,post-monsoon,\\

  17. A theoretical analysis to estimate the hydraulic properties of a loam soil from a capillary-evaporation process

    NASA Astrophysics Data System (ADS)

    Peña-Sancho, Carolina; Ghezzehei, Teamrat A.; Latorre, Borja; Moret-Fernández, David

    2015-04-01

    The determination of the water retention curve (WRC) parameters and the hydraulic conductivity (K) is of paramount importance in many scientific fields such as hydrology or environmental science. Their direct characterization, however, is typically cumbersome and time consuming. This work analyze the viability to estimate the ? and n Van Genuchten (VG) WRC parameters and K from following processes: a capillary wetting process at saturation, an evaporation process and a capillary wetting at saturation followed by an evaporation process. The theoretical analysis was carried out on a 5 cm high and 5 cm diameter cylinder filled with loam soil using numerically generated data with the HYDRUS 2D code. The error maps for the above mentioned processes and the n-K, ?-n and K-? planes were generated from the RMSE calculated between the original and the simulated cumulative curves. The deviation (%) between the optimal and original hydraulic parameters was also calculated. Results showed that the capillary plus evaporation method applied on the n-K and ?-n planes was the unique process that allowed a unique and well defined minimum. For this last case, the deviation for the ? and n parameter were 6'67 and 0'88%, respectively. Taking into account that K can be easy measured from the same soil cylinder by means of Darcy's law, we conclude the capillary + evaporation process can be a simple and effective alternative to estimate the WRC parameters. To this end, the hysteresis phenomena due to the wetting-evaporation process should be taking into account.

  18. Impact of polypropylene fibers on desiccation cracking and hydraulic conductivity of compacted clay soils

    Microsoft Academic Search

    Sami Mansour Rifai

    2000-01-01

    Compacted clay soils are commonly used as hydraulic barriers in waste containment systems such as in liners and covers for landfills, impoundments, reservoirs, and ponds. Compacted clays can minimize infiltration of fluid into waste or control the release of contaminated fluids to the surrounding soils and groundwater. The hydraulic properties of these soil-based structures can be adversely affected by desiccation

  19. Measuring Soil Hydraulic Conductivity With Microwaves

    NASA Technical Reports Server (NTRS)

    Blanchard, B. J.; Oneill, P. E.

    1985-01-01

    Soil mapping for large or small areas done rapidly. Technique requires simple radiometric measurements of L-band (15 to 30 cm) and thermal infrared emissions from ground within 2 days after saturation of surface. Technique based on observation that correlation exists between L-band emissivity and hydraulic conductivity of soil.

  20. Variation of soil hydraulic conductivity by anionic surfactants in soil column

    Microsoft Academic Search

    Dal-Heui Lee; Robert D. Cody

    2001-01-01

    Remediation techniques using surfactants to flush hydrophobic organic contaminants from soils have recently been investigated.\\u000a However, less attention has been given to evaluating the effects of surfactants on the hydraulic properties of porous media.\\u000a The objective of this study was to investigate the effects on saturated hydraulic conductivity of the interactions between\\u000a soil type (sand, clay loam) and anionic surfactants

  1. Assessing soil hydraulic characteristics using HYPROP and BEST: a comparison

    NASA Astrophysics Data System (ADS)

    Leitinger, Georg; Obojes, Nikolaus; Lassabatère, Laurent

    2015-04-01

    Knowledge of ecohydrological characteristics with high spatial resolution is a prerequisite for large-scale hydrological modelling. Data on soil hydraulic characteristics are of major importance, but measurements are often seen as time consuming and costly. In order to accurately model grassland productivity and in particular evapotranspiration, soil sampling and infiltration experiments at 25 grassland sites ranging from 900m to 2300m a.s.l. were conducted in the long term socio-ecological research (LTSER) site Stubai Valley, Tyrolean Alps, Austria, covering 265 km². Here we present a comparison of two methods to determine important hydrological properties of soils: (1) the evaporation method HYPROP (Hydraulic Property Analyzer; UMS Munich, 2010), and (2) the BEST-model (Beerkan Estimation of Soil Transfer Parameters; Lassabatère et al. (2006)), each determining the soil hydraulic characteristics and in particular the water retention curve. For the most abundant soil types we compared the pf-curves calculated from HYPROP data suing the Van Genuchten equation to the ones resulting from the comparatively time efficient BEST approach to find out if the latter is a suitable method to determine pf curves of alpine grassland soils. Except for the soil type Rendzina, the comparison of HYPROP and BEST showed slightly variations in the pF curves and resulting hydraulic characteristics. At the starting point BEST curves presented a slower dehydration, HYPROP a fast and continuous water loss. HYPROP analyses showed the highest variability in the measured values of Rendzina. Regarding BEST, the Alluvial Soils showed the highest variability. To assess equivalence between HYPROP and BEST we deduced several hydraulic characteristics from the pF curves, e.g. saturated water content, field capacity, permanent wilting point, pore size distribution, and minimum water retention. The comparison of HYPROP and BEST revealed that the results of soil water characteristics may depend on the methodological Approach with differences in equivalence between selected soil types. Thus, the used method is crucial to derive soil hydraulic parameters right from pF curves for water balance models. The results further showed that the BEST model is a promising method to determine soil water characteristics with minimal field- and laboratory work in large-scale studies. Reference: Lassabatère L, Angulo-Jaramillo R, Soria Ugalde JM, Cuenca R, Braud I and Haverkamp R (2006) Beerkan Estimation of Soil Transfer Parameters through Infiltration Experiments-BEST. Soil Sci. Soc. Am. J., 70: 521-532, doi:10.2136/sssaj2005.0026.

  2. 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)

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

    1983-01-01

    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.

  3. A sediment structure model for describing the 3D spatial distribution of soil hydraulic properties of an artificial catchment using pedotransfer functions

    NASA Astrophysics Data System (ADS)

    Maurer, T.; Bartsch, R.; Schneider, A.; Gerke, H. H.

    2012-04-01

    Modelling the spatial heterogeneity of catchments is a prerequisite for the understanding of flow processes and the application of hydrological models. The initial structure represents also the starting point for catchment and ecosystem development. The quality of hydrologic modeling is often limited due to a lack of data or an oversimplification of aquifer properties. Predictions can be significantly improved by using spatial models that reproduce specific structural characteristics. Current geostatistical methods are unable the capture spatially complex conditions, e.g. abrupt changes in structures. More deterministic structure generator approaches are currently been discussed in hydrogeology for exploration. Process-based structure generators deduce structural characteristics e.g. from the known formation processes of the aquifer. The objective was to describe the spatial distribution of soil hydraulic properties in a catchment based on generated 3D sediments distributions. The approach was tested for the artificially constructed "Hühnerwasser" ("Chicken Creek") catchment. The catchment is located in the post-lignite mining area of Welzow-Süd in Lower Lusatia, Brandenburg, Germany. Here, the initial sediment distribution was governed primarily by dumping processes of the large-scale mining technology and the geological conditions at the excavation site. For the initially organic matter-free sandy sediments, the structure model generated the distributions of soil texture and soil bulk density within dumping spoil cones. These were represented by 2D cross sections with compacted central parts and particle-segregated flanks. The 3D geometry of the catchment was generated by sequencing of these basic structural elements along identified stacker trajectories, finally yielding a discretized 3D volume model using the GOCAD software. Based on these data, spatial distributions of hydraulic properties were calculated using well-established pedotransfer functions (Vereecken et al. 1989 and Arya and Paris 1981). Qualitative comparisons of estimated hydrostatic soil moisture conditions with wetness distributions derived from aerial images suggested relatively similar patterns reflecting highly-saturated stagnant areas near compacted impact zones that originated from sediment dumping. In order to account for the remaining uncertainty in sediment composition and mass balances, different scenarios of sediment distribution were analyzed. The generated 3D-spatial distribution patterns were analyzed on different scales to determine the effects of spatial upscaling and to understand local effects on hydrological processes at larger scales. The hydraulic property distributions will be coupled with hydrological modeling, and results will be validated using hydrological monitoring data.

  4. www.VadoseZoneJournal.org Estimation of Soil Hydraulic

    E-print Network

    Hubbard, Susan

    on the physical system geometry, boundary conditions and soil hydraulic prop- erties such as the hydraulicwww.VadoseZoneJournal.org Estimation of Soil Hydraulic Parameters in the Field by Integrated approach was used to remotely infer the unsat- urated soil hydraulic parameters from time-lapse ground

  5. Effective Hydraulic Conductivity of Unsaturated Isotropic Soils with Multidimensional Heterogeneity

    SciTech Connect

    Zhang, Z. F.

    2010-05-01

    Accurate simulation and prediction of flow and transport of solutes in a heterogeneous vadose zone requires the appropriate hydraulic properties corresponding to the spatial scale of interest. Upscaling techniques provide effective properties to describe the vadose zone system’s behavior with information collected at a much smaller scale. Realizing that a saturated system can be considered as a special state of the unsaturated system, the methodologies for upscaling the saturated hydraulic conductivity of heterogeneous isotropic porous media under steady-state flow conditions can be extended for upscaling the unsaturated hydraulic conductivity. An advantage of this approach is that the extended upscaling methods are independent of the choice of hydraulic function models. The Matheron, small-perturbation, and self-consistent upscaling methods were used to demonstrate the approach. The extended upscaling methods were tested using multi-step numerical experiments of gravity-induced flow into Miller-similar synthetic soils with different levels of heterogeneity. Results show that, under 3-D flow conditions in isotropic soils, the self-consistent method applies to all the soil heterogeneity conditions considered while the Matheron and small-perturbation methods are acceptable for soil of relatively low variability.

  6. Upscaling Schemes and Relationships for the Gardner and van Genuchten Hydraulic Functions for Heterogeneous Soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Upscaled soil hydraulic properties are needed for many large-scale hydrologic applications such as regional and global climate studies and investigations of land-atmosphere interactions. Many larger scale subsurface flow and contaminant transport studies also require upscaled hydraulic property esti...

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

    E-print Network

    Stiller, Volker

    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

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

    NASA Astrophysics Data System (ADS)

    Šim?nek, Jirka; Nimmo, John R.

    2005-04-01

    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.

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

    USGS Publications Warehouse

    Simunek, J.; Nimmo, J.R.

    2005-01-01

    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.

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

    Microsoft Academic Search

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

    2001-01-01

    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

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

    E-print Network

    Paris-Sud XI, Université de

    2002-01-01

    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

  12. 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...

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

    NASA Astrophysics Data System (ADS)

    Yu, Kailiang; D'Odorico, Paolo

    2014-04-01

    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.

  14. Derivation of Soil Moisture Retention Characteristics from Saturated Hydraulic Conductivity

    E-print Network

    Kumar, C.P.

    : Knowledge of the physics of soil water movement is crucial to the solution of many problems in watershed1 Derivation of Soil Moisture Retention Characteristics from Saturated Hydraulic Conductivity C. P systems require knowledge of the relationships between soil moisture content (), soil water pressure (h

  15. 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...

  16. TDR System for Hydraulic Characterization of Unsaturated Soils in the Centrifuge John S. McCartney1

    E-print Network

    Zornberg, Jorge G.

    TDR System for Hydraulic Characterization of Unsaturated Soils in the Centrifuge John S. McCartney1@mail.utexas.edu Abstract A centrifuge permeameter has been developed to provide expedited determination of the hydraulic properties of unsaturated soils. The centrifuge permeameter is an acrylic cylinder mounted on a swinging

  17. 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...

  18. [Spatial variation characteristics of surface soil water content, bulk density and saturated hydraulic conductivity on Karst slopes].

    PubMed

    Zhang, Chuan; Chen, Hong-Song; Zhang, Wei; Nie, Yun-Peng; Ye, Ying-Ying; Wang, Ke-Lin

    2014-06-01

    Surface soil water-physical properties play a decisive role in the dynamics of deep soil water. Knowledge of their spatial variation is helpful in understanding the processes of rainfall infiltration and runoff generation, which will contribute to the reasonable utilization of soil water resources in mountainous areas. Based on a grid sampling scheme (10 m x 10 m) and geostatistical methods, this paper aimed to study the spatial variability of surface (0-10 cm) soil water content, soil bulk density and saturated hydraulic conductivity on a typical shrub slope (90 m x 120 m, projected length) in Karst area of northwest Guangxi, southwest China. The results showed that the surface soil water content, bulk density and saturated hydraulic conductivity had different spatial dependence and spatial structure. Sample variogram of the soil water content was fitted well by Gaussian models with the nugget effect, while soil bulk density and saturated hydraulic conductivity were fitted well by exponential models with the nugget effect. Variability of soil water content showed strong spatial dependence, while the soil bulk density and saturated hydraulic conductivity showed moderate spatial dependence. The spatial ranges of the soil water content and saturated hydraulic conductivity were small, while that of the soil bulk density was much bigger. In general, the soil water content increased with the increase of altitude while it was opposite for the soil bulk densi- ty. However, the soil saturated hydraulic conductivity had a random distribution of large amounts of small patches, showing high spatial heterogeneity. Soil water content negatively (P < 0.01) correlated with the bulk density and saturated hydraulic conductivity, while there was no significant correlation between the soil bulk density and saturated hydraulic conductivity. PMID:25223011

  19. 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.3×10-5 Number of Observations 10 10 10 34 34 4 4 4 #12;A-2 Table A3. Hydraulic properties statistics

  20. Comparison of multiple scaling approaches for soil hydraulic parameters

    NASA Astrophysics Data System (ADS)

    Jana, R. B.; Mohanty, B. P.

    2012-12-01

    Understanding how soil hydraulic parameters (and hence soil moisture distribution) are affected at different scales by the spatial variability of influencing factors such as soil structure and texture, vegetation, and topography is an inherent requirement of efficient scaling schemes. While it is known that connections exist between these land surface attributes and the soil hydraulic parameters, the exact mathematical and/or physical nature of these relationships is generally unknown. In a study analyzing the importance of topography in scaling schemes for soil hydraulic parameters at hillslope scales, four different aggregation methods were applied to scale soil hydraulic parameters from a 30 m resolution to a 1 km resolution across the Little Washita watershed in Oklahoma. A simple homogenization method, a Markov chain Monte Carlo (MCMC)-based stochastic technique, a Bayesian neural network (BNN) approach, and a topography-based aggregation scheme were analyzed in this study. The equivalence of the upscaled parameters was tested by simulating flow for the watershed in HYDRUS-3D, and comparing the resultant soil moisture states with remote sensing data at the pixel scale. Results show considerable correlations between simulated and observed soil moisture states across time, topographic variations, and land cover for techniques that incorporate topographic information in their routines. The study highlights that at the kilometer scale, soil is no longer the sole controlling factor for soil moisture distribution, and that topography plays a dominant role.

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

    Microsoft Academic Search

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

    2001-01-01

    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

  2. www.VadoseZoneJournal.org Es ma on of Soil Hydraulic

    E-print Network

    Hubbard, Susan

    system geometry, boundary conditions and soil hydraulic prop- erties such as the hydraulic conductivitywww.VadoseZoneJournal.org Es ma on of Soil Hydraulic Parameters in the Field by Integrated approach was used to remotely infer the unsaturated soil hydraulic parameters from me-lapse ground

  3. Changes in hydraulic soil conductivity in the walls of zoogenic macropores due to the soil compaction

    NASA Astrophysics Data System (ADS)

    Pelíšek, Igor

    2015-04-01

    This study focuses on assessement of the hydric functions and effectiveness of the preferential zoogenic routes (preferentially lumbricid burrows), with primary focus on the hydric functions and parameters of individual vertical tubular macropores and on the analysis of selected possible detailed effects on these functions. The effect of earthworms (Lumbricidae) on the physical soil properties is notable. During burrowing, earthworms press the material in the vicinity of the hollowed burrows. Several variants of the relationship between the macropores and the soil compaction, permeability and erodibility were verified. Both measurements in the field and laboratory tests of intact collected samples and engineered samples were performed. With regard to preferential focus on the hydraulic processes in gravity macropores, to the limits of the instrumentation and the size of individual earthworms in agricultural soils in the Czech Republic, we assessed the processes in the macropores with diameter of ca 5 mm or larger. In some cases, saturated hydraulic conductivity of zoogenic macropore walls was reduced in order of tens of percent compared with hydraulic conductivity of soil matrix, and the increase of bulk density of soil in the macropore vicinity achieved 25%. The effect of repeated rise and water level stagnation (repeated macropore washing during multiple wetting cycles) was tested. Investigation of water erosion of macropores was limited by adjustable flow, vessel capacity and pump capacity of the accurate continuous infiltrometer. Investigation of the water inlet from above gave more data on the washed-off material in the selected time intervals. Analysis of water rise from below and macropore sealing provided one cumulative data for each testing period.

  4. The temporal changes in saturated hydraulic conductivity of forest soils

    NASA Astrophysics Data System (ADS)

    Kornél Szegedi, Balázs

    2015-04-01

    I investigated the temporal variability of forest soils infiltration capacity through compaction. I performed the measurements of mine in The Botanical Garden of Sopron between 15.09.2014 - 15.10.2014. I performed the measurements in 50-50 cm areas those have been cleaned of vegetation, where I measured the bulk density and volume of soil hydraulic conductivity with Tension Disk Infiltrometer (TDI) in 3-3 repetitions. I took undisturbed 160 cm3 from the upper 5 cm layer of the cleaned soil surface for the bulk density measurements. Then I loosened the top 10-15 cm layer of the soil surface with spade. After the cultivation of the soil I measured the bulk density and volume of water conductivity also 3-3 repetitions. Later I performed the hydraulic conductivity (Ksat) using the TDI and bulk density measurements on undisturbed samples on a weekly basis in the study area. I illustrated the measured hydraulic conductivity and bulk density values as a function of cumulative rainfall by using simple graphical and statistical methods. The rate of the soil compaction pace was fast and smooth based on the change of the measured bulk density values. There was a steady downward trend in hydraulic conductivity parallel the compaction. The cultivation increased the hydraulic conductivity nearly fourfold compared to original, than decreased to half by 1 week. In the following the redeposition rate declined, but based on the literature data, almost 3-4 months enough to return the original state before cultivation of the soil hydraulic conductivity and bulk density values. This publication has been supported by AGRARKLIMA.2 VKSZ_12-1-2013-0034 project.

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

    E-print Network

    Zornberg, Jorge G.

    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

  6. Numerical modeling of consolidation processes in hydraulically deposited soils

    NASA Astrophysics Data System (ADS)

    Brink, Nicholas Robert

    Hydraulically deposited soils are encountered in many common engineering applications including mine tailing and geotextile tube fills, though the consolidation process for such soils is highly nonlinear and requires the use of advanced numerical techniques to provide accurate predictions. Several commercially available finite element codes poses the ability to model soil consolidation, and it was the goal of this research to assess the ability of two of these codes, ABAQUS and PLAXIS, to model the large-strain, two-dimensional consolidation processes which occur in hydraulically deposited soils. A series of one- and two-dimensionally drained rectangular models were first created to assess the limitations of ABAQUS and PLAXIS when modeling consolidation of highly compressible soils. Then, geotextile tube and TSF models were created to represent actual scenarios which might be encountered in engineering practice. Several limitations were discovered, including the existence of a minimum preconsolidation stress below which numerical solutions become unstable.

  7. Capillary bundle model of hydraulic conductivity for frozen soil Kunio Watanabe1

    E-print Network

    Flury, Markus

    Capillary bundle model of hydraulic conductivity for frozen soil Kunio Watanabe1 and Markus Flury2: Watanabe, K., and M. Flury (2008), Capillary bundle model of hydraulic conductivity for frozen soil, Water

  8. A survey of soil physical properties on sheep and dairy farms in southern New Zealand

    Microsoft Academic Search

    J. J. Drewry; R. P. Littlejohn; R. J. Paton

    2000-01-01

    The study compared soil macroporosity, bulk density, air permeability, and hydraulic conductivity on 97 sheep and 87 dairy farm sites surveyed in Southland and South Otago, New Zealand. Soil physical properties of 4 soil groups (15 soils) were investigated. Soils on sheep farms surveyed had significantly greater air permeability than soils on dairy farms, averaged over 0–15 cm. Soils on

  9. ORIGINAL PAPER Hydraulic properties and embolism in small-diameter

    E-print Network

    Paris-Sud XI, Université de

    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

  10. Comparison of Soil Hydraulic Parameterizations for Mesoscale Meteorological Models.

    NASA Astrophysics Data System (ADS)

    Braun, Frank J.; Schädler, Gerd

    2005-07-01

    Soil water contents, calculated with seven soil hydraulic parameterizations, that is, soil hydraulic functions together with the corresponding parameter sets, are compared with observational data. The parameterizations include the Campbell/Clapp-Hornberger parameterization that is often used by meteorologists and the van Genuchten/Rawls-Brakensiek parameterization that is widespread among hydrologists. The observations include soil water contents at several soil depths and atmospheric surface data; they were obtained within the Regio Klima Projekt (REKLIP) at three sites in the Rhine Valley in southern Germany and cover up to 3 yr with 10-min temporal resolution. Simulations of 48-h episodes, as well as series of daily simulations initialized anew every 24 h and covering several years, were performed with the “VEG3D” soil-vegetation model in stand-alone mode; furthermore, 48-h episodes were simulated with the model coupled to a one-dimensional atmospheric model. For the cases and soil types considered in this paper, the van Genuchten/Rawls-Brakensiek model gives the best agreement between observed and simulated soil water contents on average. Especially during episodes with medium and high soil water content, the van Genuchten/Rawls-Brakensiek model performs better than the Campbell/Clapp-Hornberger model.

  11. Hydraulic conductivity estimation for soils with heterogeneous pore structure

    Microsoft Academic Search

    Wolfgang Durner

    1994-01-01

    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

  12. Seasonal variability of near-saturated hydraulic conductivity on cultivated soil

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

  13. 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...

  14. Comparison of methods for determining soil hydraulic characteristics 

    E-print Network

    Byrd Humphreys, Kathryn

    1979-01-01

    content determined from centrifuge data for noted soil depths 60 29 Comparison of laboratory to field hydraulic conductivity, 0-30 cm soil depth 61 30 Comparison of laboratory to field hydraulic conductivity, 40-80 cm soil depth . 62 A-3 Double... = HBt Rv2 t FRc f HBI dt 0 (I 2) 14 CURVE PARAMETER /R 0 O. I 0 2 C3 I? 0- 0. 13 0. 20 0. 30 0. 40 0 30 I. 10 0. 6 0. 70 0 D/Rc CURVE PARAMETER /R 2 CO I? ?C 0. 10 0. 15 0. 20 CO 0. 30 0. 40 0. 50 0. 6 0 0. 70 0. 80 1000...

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

    PubMed Central

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

    2014-01-01

    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

  16. HYDRAULIC AND PHYSICAL PROPERTIES OF MCU SALTSTONE

    SciTech Connect

    Dixon, K; Mark Phifer, M

    2008-03-19

    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.

  17. HYDRAULIC CONDUCTIVITY ESTIMATION IN PARTIALLY SATURATED SOILS USING THE ADJOINT METHOD

    E-print Network

    Efendiev, Yalchin

    HYDRAULIC CONDUCTIVITY ESTIMATION IN PARTIALLY SATURATED SOILS USING THE ADJOINT METHOD J. SANTOS for the estimation of the saturated hydraulic conductivity k in a partially saturated soil Q is proposed. Groundwater exam- ple showing the implementation of the algorithm to estimate the saturated hydraulic conductivity

  18. Agricultural use of soil, consequences in soil organic matter and hydraulic conductivity compared with natural vegetation in central Spain

    NASA Astrophysics Data System (ADS)

    Vega, Verónica; Carral, Pilar; Alvarez, Ana Maria; Marques, Maria Jose

    2014-05-01

    When ecosystems are under pressure due to high temperatures and water scarcity, the use of land for agriculture can be a handicap for soil and water conservation. The interactions between plants and soils are site-specific. This study provides information about the influence of the preence vs. The absence of vegetation on soil in a semi-arid area of the sout-east of Madrid (Spain, in the Tagus River basin. In this area soil materials are developed over a calcareous-evaporitic lithology. Soils can be classified as Calcisols, having horizons of accumulation with powdered limestone and irregular nodules of calcium carbonate. They can be defined as Haplic Cambisols and Leptic Calcisols (WRB 2006-FAO). The area is mainly used for rainfed agriculture, olive groves, vineyards and cereals. There are some patches of bushes (Quercus sp.) and grasses (Stipa tenacissima L.) although only found on the top of the hills. This study analyses the differences found in soils having three different covers: Quercus coccifera, Stipa tenacissima and lack of vegetation. This last condition was found in the areas between cultivated olive trees. Soil organic matter, porosity and hydraulic conductivity are key properties of soil to understand its ability to adapt to climate or land use changes. In order to measure the influence of different soil covers, four replicates of soil were sampled in each condition at two soil depth, (0-10 cm and 10-20 cm). Hydraulic conductivity was measured in each soil condition and replicate using a Mini-disk® infiltrometer. There were no differences between the two depths sampled. Similarly, there were no changes in electric conductivity (average 0.1±0.03 dS m-1); pH (8.7±0.2) or calcium carbonate content (43±20 %). Nevertheless, significant differences (p>0.001) were found in soil organic matter. The maximum was found in soils under Quercus (4.7±0.5 %), followed by Stipa (2.2±1.1 %). The soil without vegetation in the areas between olive trees had only 0.7±1.1 % soil organic matter; far from the usual limit advisable for cultivated soils. Soil porosity was also affected in cultivated soils, being 39±5% (total porosity), significantly less than those found under Stipa (46%) and Quercus (51%). Hydraulic conductivity presented a similar pattern to porosity, being higher in soils under Quercus, however further research is needed to clarify this result, as it can also be related to changes detected in soil texture. Sand content, which was different between soil conditions, is highly correlated to hydraulic conductivity. Changes in soil texture can be due to erosive processes that have to be studied to establish the causative relationships between these findings. Acknowledgements: Project CGL 2008-04296. Environmental Impact evaluation through the assessment of soil organic matter resilient forms in soils.

  19. Atlas of soil reflectance properties

    NASA Technical Reports Server (NTRS)

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

    1979-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

    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

    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.

  1. Effect of sheep stocking intensity on soil physical properties and dry matter production on a Pallic Soil in Southland

    Microsoft Academic Search

    J. J. Drewry; J. A. H. Lowe; R. J. Paton

    1999-01-01

    This 3?year study examined the extent of damage to soil physical properties of a Pukemutu silt loam (Pallic Soil) and the loss of ryegrass?white clover pasture production caused by intensive winter grazing at 1800 sheep ha. Macroporosity, pore size distribution, bulk density, and hydraulic conductivity were measured at 5?cm incremental soil depths to 15 cm to assess changes in soil

  2. Soil Moisture Variability and Mean Soil Moisture: A Stochastic Hydraulic Perspective

    NASA Astrophysics Data System (ADS)

    Vereecken, H.; Kamai, T.; Harter, T.; Kasteel, R.; Hopmans, J. W.; Vanderborght, J.

    2007-12-01

    Soil moisture is a key variable in understanding water and energy fluxes in terrestrial systems. The characterization of soil moisture variability is one of the major challenges in hydrological sciences today. Especially the relationship between soil moisture variability and mean soil water content is receiving considerable attention as it plays an important in upscaling and downscaling of soil moisture fields and in the parameterization of terrestrial and climate models. We show that the relationship between mean moisture content and its standard deviation can be predicted by stochastic analysis of unsaturated Brooks-Corey flow in heterogeneous soils. Based on a sensitivity analysis, it is found that parameters of the moisture retention characteristic and their spatial variability determine to a large extent the shape of the soil moisture variance-mean water content function. Predicting this function for eleven textural classes we found that the standard deviation of soil moisture peaked between 0.17 and 0.23 for most textural classes. Differing values were found for the more sandy soils. The simulated range of soil moisture agrees with field findings reported in the literature. It was found that pore-size distribution of soils is the primary parameter controlling the maximum value of the soil moisture standard deviation. We demonstrate the potential of inversely estimating soil hydraulic parameters and their statistics from soil moisture data using a case study with generated functions.

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

    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.

  4. Ecohydrological controls on soil moisture and hydraulic conductivity within a pinyon-juniper woodland

    USGS Publications Warehouse

    Lebron, I.; Madsen, M.D.; Chandler, D.G.; Robinson, D.A.; Wendroth, O.; Belnap, J.

    2007-01-01

    The impact of pinyon-juniper woodland encroachment on rangeland ecosystems is often associated with a reduction of streamflow and recharge and an increase in soil erosion. The objective of this study is to investigate vegetational control on seasonal soil hydrologic properties along a 15-m transect in pinyon-juniper woodland with biocrust. We demonstrate that the juniper tree controls soil water content (SWC) patterns directly under the canopy via interception, and beyond the canopy via shading in a preferred orientation, opposite to the prevailing wind direction. The juniper also controls the SWC and unsaturated hydraulic conductivity measured close to water saturation (K(h)) under the canopy by the creation of soil water repellency due to needle drop. We use this information to refine the hydrologic functional unit (HFU) concept into three interacting hydrologic units: canopy patches, intercanopy patches, and a transitional unit formed by intercanopy patches in the rain shadow of the juniper tree. Spatial autoregressive state-space models show the close relationship between K(h) close to soil water saturation and SWC at medium and low levels, integrating a number of influences on hydraulic conductivity. Copyright 2007 by the American Geophysical Union.

  5. Modelling the effect of rock fragment on soil saturated hydraulic conductivity

    NASA Astrophysics Data System (ADS)

    Pellegrini, Sergio; Costanza Andrenelli, Maria; Vignozzi, Nadia

    2014-05-01

    Stoniness may be a key factor in determining the soil hydrological properties. Nevertheless, how coarse fraction takes part in some important processes (e.g., runoff, infiltration and percolation) is not univocally recognized, mainly because of the difficulties in obtaining reliable experimental data and, secondarily, for the employment of different approaches to evaluate the role of the coarse fraction. With that regard, equations developed by hydrogeologists to account for water fluxes in porous media, consider permeability as mere function of grain size distribution (particles >2 mm included), with permeability values increasing when passing from sand to gravel. Conversely, soil scientists consider the saturated hydraulic conductivity (Ksat) of soil exclusively as function of the fine-earth fraction and attribute a contrasting effect to the coarse fraction, both in relation to the decrease of porosity and to the increase of flow path tortuosity. Nevertheless, the Soil Survey Handbook includes all fragmental soils (gravel content ?35% by weight) into the highest class of soil hydraulic conductivity, and this partly disagrees with the mostly adopted soil scientists' approaches. At the same time, lab- experiments carried out by engineers on particle mixture point out that the addition of increasing amounts of coarse material to finer grains progressively reduces the overall porosity until a critical threshold is reached; beyond this level, the void proportion rises again. In relation to the engineers' results, the present paper attempts to conceptually approach the dual effects of rock fragment content on Ksat by considering a decay of the water transmission properties of the fine-earth fraction at low gravel contents and, conversely, a drastic improvement of the conductivity whenever the porosity increases. For that purpose a data set of 50 soils of different textural classes is used to define the procedure by virtually increasing the rock fragment fraction (SK) up to 99% by weight, meanwhile calculating the corresponding statistical descriptors (e.g., d10, dg, ??) of grain size distribution (GSD). For each sample of the data set, the procedure is based on the Ksat computation for increasing gravel content provided by both soil scientists' and hydrogeologists' approaches. Given that the two methods generate curves with different direction and slope, an intersection is obtained. Such a point indicates the minimum saturated hydraulic conductivity value, that can be conceptually interpreted as the minimum porosity (or the maximum density of the mixture) experimentally observed by engineers. Therefore, the procedure for assessing the resulting Ksat consists in adopting the soil scientists' approach until the intersection is reached and then following the hydrogeological curve beyond such threshold. The findings provided by two other approaches are compared with our results and discussed.

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

    NASA Astrophysics Data System (ADS)

    Boadu, F. K.

    2002-05-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

  8. Soil hydraulic conductivity changes caused by irrigation with reclaimed waste water

    SciTech Connect

    Levy, G.J.; Rosenthal, A.; Tarchitzky, J.; Shainberg, I.; Chen, Y.

    1999-10-01

    Use of reclaimed waste water (RWW) in arid and semiarid regions may alleviate problems of fresh water shortage; however, it also involves some potential risks among which are degradation of soil hydraulic properties. The objectives of the current study were to study the effects of organic matter (OM) loads found in RWW obtained from a secondary treatment plant in Tel Aviv, Israel, and different size fractions of the suspended solids in the RWW on the hydraulic conductivity (HC) of three Israeli soils. The hydraulic conductivity of a clayey grumusol (Typic Chromoxerert), a typic loamy loess (Calcic Haploxeralf), and a sandy loam hamra (Typic Rhodexeralf) was determined in the laboratory using soil columns, by leaching with RWW containing zero, low, or high OM load, followed by leaching with distilled water (DW). The effects of suspended solids' size fraction on the HC was determined by filtering RWW. Leaching with high OM load RWW caused the relative HC of the grumusol, loess and hamra to drop to final values of 13.9, 24.2, and 58.8%, respectively. Filtering out suspended solids {gt}1.2 {micro} in this water improved the HC of the hamra, but did not significantly affect the final relative HC of the grumusol and loess. Leaching with low OM load RWW did not significantly decrease the HC beyond the decrease attributed to the effects of the concentration and composition of the electrolytes present in the zero OM load RWW. Subsequent leaching with DW caused an additional decrease in HC, whose magnitude for a given soil did not depend on the quality of the RWW previously used. The presence of OM in the irrigation water did not seem to have significant residual effects on soil HC. Evidently, in high OM load RWW the OM fraction determines the soils' HC, whereas in low OM load RWW, it is the electrolyte concentration and composition in the water, that seem to pose the hazard to soil hydraulic properties, especially during subsequent leaching with DW.

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

    NASA Technical Reports Server (NTRS)

    Arya, L. M. (principal investigator)

    1980-01-01

    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.

  10. Monitoring infiltration with time-lapse relative gravity: An option for non-invasive determination of soil hydraulic parameters?

    NASA Astrophysics Data System (ADS)

    Bauer-Gottwein, P.

    2012-04-01

    Various hydrogeophysical methods have been proposed to monitor infiltration and determine soil hydraulic parameters using coupled hydrogeophysical inversion. Methods include electrical resistivity tomography (ERT), ground penetrating radar (GPR, both surface and cross-hole) as well as passive microwave radiometry. Depending on the measurement set-up, both ERT and GPR can provide high-resolution images of soil water content. However, soil water content monitoring with both ERT and GPR depends on the validity and accuracy of empirical relationships linking soil water content to electrical resistivity (ERT) and dielectric permittivity (GPR). This has emerged as one of the main limitations for the performance of soil water monitoring with both GPR and ERT. As an alternative, ground-based time-lapse relative gravity (TLRG) is proposed for infiltration monitoring. The method is based on the fact that water content changes in the subsurface constitute changes in subsurface density and can be monitored as changes in the gravitational field. The advantage of TLRG over GPR and ERT is that TLRG directly senses mass changes. Thus, no empirical relationship is required to link water content changes to changes in a geophysical property. This study evaluates the performance of TLRG for infiltration monitoring and hydrogeophysical inversion of soil hydraulic parameters. Results include both synthetic infiltration experiments and a real-world infiltration experiment monitored with TLRG. In the synthetic experiments, soil water content profiles are generated using analytical infiltration solutions. Soil water content profiles are translated into gravity signals and are corrupted with random noise to produce synthetic data. The synthetic data is subsequently used in a hydrogeophysical inversion of soil hydraulic parameters. Fitted parameter confidence intervals and covariances are evaluated. The same inversion procedure is used on the real-world data. The results show that TLRG data contains information that constrains soil hydraulic parameters. However, useful signal-to-noise ratios require large amounts of infiltration. TLRG sensing of infiltration is thus limited to deep soil profiles and long-duration infiltration events.

  11. Hydraulic properties of the crystalline basement

    Microsoft Academic Search

    Ingrid Stober; Kurt Bucher

    2007-01-01

    Hydraulic tests in boreholes, up to 4.5 km deep, drilled into continental crystalline basement revealed hydraulic conductivity\\u000a (K) values that range over nine log-units from 10?13?10?4 m s?1. However, K values for fractured basement to about 1 km depth are typically restricted to the range from 10?8 to 10?6 m s?1. New data from an extended injection test at the KTB research site (part

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

    EPA Science Inventory

    Nocturnal increases in water potential (¿) and water content (¿) 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 ...

  13. 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...

  14. Long-term hydraulic properties of subsurface flow constructed wetlands

    E-print Network

    Turner, Glenn Allen

    1994-01-01

    LONG-TERM HYDRAULIC PROPERTIES OF SUBSURFACE FLOW CONSTRUCTED WETLANDS A Thesis by GLENN ALLEN TURNER Submitted to the Office of Graduate studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER... OF SCIENCE December 1994 Major Subject: Agricultural Engineering LONG-TERM HYDRAULIC PROPERTIES OF SUBSURFACE FLOW CONSTRUCTED WETLANDS by GLENN ALLEN TURNER Submitted to Texas A&M University in partial fulfdlment of the requirements for the degree...

  15. Role of precipitation uncertainty in the estimation of hydrologic soil properties using remotely sensed soil moisture in a semiarid environment

    Microsoft Academic Search

    Christa D. Peters-Lidard; David M. Mocko; Matthew Garcia; Joseph A. Santanello; Michael A. Tischler; M. Susan Moran; Yihua Wu

    2008-01-01

    The focus of this study is on the role of precipitation uncertainty in the estimation of soil texture and soil hydraulic properties for application to land-atmosphere modeling systems. This work extends a recent study by Santanello et al. (2007) in which it was shown that soil texture and related physical parameters may be estimated using a combination of multitemporal microwave

  16. 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

  17. Characterization of the hydraulic properties of fractures in chalk.

    PubMed

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

    2003-01-01

    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

  18. Hydraulics.

    ERIC Educational Resources Information Center

    Decker, Robert L.; Kirby, Klane

    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)…

  19. Plant hydraulic lift of soil water – implications for crop production and land restoration

    Microsoft Academic Search

    Hans-Holger Liste; Jason C. White

    2008-01-01

    Water more than other factors limits growth and productivity of terrestrial plants. Strategies of plants to cope with soil\\u000a drought include hydraulic redistribution of water via roots from moist to dry soil. During periods of drought, water may be\\u000a transported upward through root systems from moister subsurface to dry surface soil by a process known as “hydraulic lift”\\u000a (HL). On

  20. Hydraulic and thermal soil Parameter combined with TEM data at quaternary coastal regions

    NASA Astrophysics Data System (ADS)

    Grabowski, Ima; Kirsch, Reinhard; Scheer, Wolfgang

    2014-05-01

    In order to generate a more efficient method of planning and dimensioning small- and medium sized geothermal power plants at quaternary subsurface a basic approach has been attempted. Within the EU-project CLIWAT, the coastal region of Denmark, Germany, Netherlands and Belgium has been investigated and air borne electro magnetic data was collected. In this work the regional focus was put on the isle of Föhr. To describe the subsurface with relevant parameters one need the information from drillings and geophysical well logging data. The approach to minimize costs and use existing data from state agencies led the investigation to the combination of specific electrical resistivity data and hydraulic and thermal conductivity. We worked out a basic soil/hydraulic conductivity statistic for the isle of Föhr by gathering all well logging data from the island and sorted the existing soil materials to associated kf -values. We combined specific electrical resistivity with hydraulic soil properties to generate thermal conductivity values by extracting porosity. Until now we generated a set of rough data for kf - values and thermal conductivity. The air borne TEM data sets are reliable up to 150 m below surface, depending on the conductivity of the layers. So we can suppose the same for the differentiated parameters. Since this is a very rough statistic of kf -values, further more investigation has to be made. Although the close connection to each area of investigation either over existing logging data or laboratory soil property values will remain necessary. Literature: Ahmed S, de Marsily G, Talbot A (1988): Combined Use of Hydraulic and Electrical Properties of an Aquifer in a Geostatistical Estimation of Transmissivity. - Groundwater, vol. 26 (1) Burschil T, Scheer W, Wiederhold H, Kirsch R (2012): Groundwater situation on a glacially affected barrier island. Submitted to Hydrology and Earth System Sciences - an Interactive Open Access Journal of the European Geosciences Union Burval Working Group (2006) Groundwater Resources in buried valleys- a challenge for Geosciences. - Leibniz-Institut für Angewandte Geophysik, Hannover Scheer W, König B, Steinmann F (2012): Die Grundwasserverhältnisse von Föhr. - In: Der Untergrund von Föhr: Geologie, Grundwasser und Erdwärme - Ergebnisse des INTERREG-Projektes CLIWAT. - Landesamt für Landwirtschaft, Umwelt und ländliche Räume Schleswig-Holstein, Flintbek

  1. 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...

  2. Effects of model layer simplification using composite hydraulic properties

    USGS Publications Warehouse

    Sepulveda, Nicasio; Kuniansky, Eve L.

    2010-01-01

    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.

  3. 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...

  4. 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...

  5. Estimating hydraulic conductivities of the soil aggregates and their clay-organic coatings using numerical inversion of capillary rise data

    NASA Astrophysics Data System (ADS)

    Fér, Miroslav; Kodešová, Radka

    2012-10-01

    SummarySoil aggregates are in some soils and their horizons covered by organomineral coatings, which may significantly influence water and solute transfer into the aggregates. Knowledge of a coating occurrence, their structure and hydraulic properties is required for a more precise description of water flow and contaminant transport in soils. The aim of this study was to describe hydraulic properties of clay and organic matter coatings in the iluvial (Bt2) horizon of Haplic Luvisol. Sets of 30 unsorted aggregates, 24 aggregates with mostly clay coatings and 24 aggregates with clay-organic coatings, respectively, were studied to evaluate an impact of various coating composition. The coatings were removed from a half of the aggregates of each set. First, the wetting soil-water retention curve was measured on all soil aggregates. Then the capillary rise from the saturation pan into the multiple aggregates (set of 14 or 15 aggregates) without and with coatings was measured. Numerical inversion of the measured cumulative capillary rise data using the HYDRUS-1D program were applied to estimate the saturated hydraulic conductivities of the aggregates, Ks,aggr, and their coatings, Ks,coat. Results were compared with saturated hydraulic conductivities evaluated analytically using the sorptivity method, which was proposed previously. Data of the soil-water retention curves, measured on aggregates with and without coatings, did not allow distinguishing between retention curve parameters of the soil aggregates and their coatings. Therefore the same parameters were evaluated for both. Capillary rise into the soil aggregates without coatings was always faster than into the aggregates with coatings. As result the optimized saturated hydraulic conductivities, Ks,coat, of the clay and the organic matter coatings (the average values for unsorted, mostly clay and clay-organic coatings were 3.69 × 10-7, 2.76 × 10-7 and 1.81 × 10-7 cm min-1, respectively) were one to two order of magnitude lower than the saturated hydraulic conductivities, Ks,aggr, of the aggregates (the average values for corresponding aggregates were 3.87 × 10-6, 6.52 × 10-6 and 1.11 × 10-5 cm min-1, respectively). Slightly variable Ks,aggr (or Ks,coat) values were obtained for different bottom pressure heads, and the lower Ks,aggr (or Ks,coat) values were estimated from the second run of the tests compare to the first run of tests for each set of aggregates. No statistically significant differences between Ks,coat values obtained for coatings of various compositions were found. Resulting Ks,aggr values were in the range of the values obtained analytically.

  6. Hydraulics.

    ERIC Educational Resources Information Center

    Engelbrecht, Nancy; And Others

    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…

  7. Kriging analysis of soil properties

    Microsoft Academic Search

    Gilbert C. Sigua; Wayne H. Hudnall

    2008-01-01

    Background, aim, and scope  Soil as a landscape body contains wide ranges of physical, chemical, morphological, and mineralogical properties, both laterally\\u000a and vertically. Soils with similar properties and environments are expected to behave similarly. A statement on land use potential\\u000a will depend in part on the precision and accuracy of the statements that can be made about the soils. This information

  8. 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

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

    E-print Network

    Naghshineh-Pour, Bijan

    1968-01-01

    of MASTER OF SCIENCE May 1968 Major Subject: Soil Chemistry THE EFFECT OF ELECTROLYTE COMPOSITION ON HYDRAULIC CONDUCTIVITY ON SOME TEXAS SOILS A Thesis By BI JAN NAGHSHINEH-POUR App as to style and content by: (C irman f Committe ( ember) ember... OF FIGURES Figure Page Diagram of the permeameter constructed for the experiment 15 Ternary diagram showing the effect of salt con- centration and SAR on hydraulic conductivity of Houston Black clay Ternary diagram showing the effect of salt con...

  10. Use of limited soil property data and modeling to estimate root zone soil water content

    NASA Astrophysics Data System (ADS)

    Starks, Patrick J.; Heathman, Gary C.; Ahuja, Lajpat R.; Ma, Liwang

    2003-03-01

    Estimation of soil water content in the root zone with time in different parts of a watershed is important for both strategic and tactical management of water resources, as well as of agricultural production, water quality, and soil resources. This estimation requires detailed knowledge of rainfall intensities and meteorological variables over space and time, as well as the physical and hydraulic properties of the soil horizons and plant growth information. However, all this detailed spatial information is extremely expensive and time consuming to obtain. New technologies are helping to increase the spatial sampling of rainfall and other meteorological variables, but spatially detailed measurement of soil properties is still not practical. The best we can obtain from the existing soil survey database is the spatial distribution of soil textural class. We investigated the use of a hierarchy of limited soil input data, ranging from soil textural class of soil horizons alone, to measured soil texture and bulk densities of horizons, additional lab or field measurement of -33 kPa soil water content, to additional field measurement of average saturated hydraulic conductivity. These five modeling scenarios, along with meteorological and plant information, were input to the Root Zone Water Quality Model (RZWQM) to estimate 0-60 cm soil water content over a 30-day period in 1997 at the Little Washita River Experimental Watershed in Oklahoma. The estimated water contents were compared with time-domain reflectometry (TDR) profile measurements and gravimetric samplings of soil surface moisture. In addition to the five scenarios using limited input data, a more detailed set of data based on laboratory measured soil water retention curves and field measured saturated conductivity was supplied to the model for all Brooks-Corey function parameters (full description mode). Estimates of root zone soil water content using detailed input were compared to estimates obtained using minimum input data. Adjustments in specific hydraulic parameters were also made in an effort to calibrate the model to the soils in this region. Overall, reasonable agreement was found between TDR-measured and RZWQM-predicted average water contents for 0-60 cm depths. Surprisingly, the smallest errors in the predicted water contents were achieved using either the textural class only or the hydraulic properties determined in situ, with root mean square errors ranging from 0.012 to 0.018 m 3 m -3. Hence, the model provided adequate estimates of average profile soil water content based on textural class-name only which was considered the most limited input data condition.

  11. Plant roots can actively regulate hydraulic redistribution by modifying the hydraulic properties of the rhizosphere using exudates

    NASA Astrophysics Data System (ADS)

    Ghezzehei, Teamrat; Bogie, Nathaniel; Albalasmeh, Ammar

    2015-04-01

    The phenomenon of hydraulic lift by roots of plants has been observed in many arid and semi-arid regions. The process involves water transfer from moist deep soil zone to shallow and dry layers, typically at night when transpiration is shut off. The widely held explanation is that hydraulic lift receives the strong water potential gradient created during the day when the plants are actively transpiring. However, it is not fully understood whether hydraulic lift is actively controlled by plants or it is a spontaneous response to the occurrence of pressure gradient. Here, we will present modeling study that demonstrates that plant roots can exert significant control on hydraulic redistribution via exudation and formation of rhizospheath. The model is based on results of potted experiments conducted by Nambiar in 1976 (Plant and Soil, 44:267-271), which have shown that plants are able to acquire essential micronutrients from very dry soil so long as water is available to the root system in sufficient quantity elsewhere. He also observed that the roots in the water-depleted zones exhibited evidence of substantial root exudation, which suggests that exudates are needed in order to provide moisture for mobilization and diffusion of nutrients in the dry regions. In addition, our own recent model-based research demonstrated that exudates play important role in facilitating water flow in otherwise dry rhizosphere region. Our models show that exudates facilitate the release of hydraulically lifted water to the rhizosphere by ensuring hydraulic continuity between the root walls and the surrounding dry soil. In addition, the high water retention capacity of root exudates permits the hydraulic conductivity to remain elevated even at low potential conditions. The results of this modeling study suggest that hydraulic lift is an actively controlled adaptation mechanism that allows plants to remain active during long dry spells by acquiring nutrients from the dry near surface soils while relying on deep soil moisture reserves for transpiration.

  12. Changes in petiole hydraulic properties and leaf water flow in birch and oak saplings in a CO2-enriched atmosphere.

    PubMed

    Eguchi, Norikazu; Morii, Noriko; Ueda, Tatsushiro; Funada, Ryo; Takagi, Kentaro; Hiura, Tsutom; Sasa, Kaichiro; Koike, Takayoshi

    2008-02-01

    Water relations in woody species are intimately related to xylem hydraulic properties. High CO(2) concentrations ([CO(2)]) generally decrease transpiration and stomatal conductance (g(s)), but there is little information about the effect of atmospheric [CO(2)] on xylem hydraulic properties. To determine the relationship between water flow and hydraulic structure at high [CO(2)], we investigated responses of sun and shade leaves of 4-year-old saplings of diffuse-porous Betula maximowicziana Regel and ring-porous Quercus mongolica Fisch. ex Ledeb. ssp. crispula (Blume) Menitsky grown on fertile brown forest soil or infertile volcanic ash soil and exposed to 500 micromol CO(2) mol(-1) for 3 years. Regardless of species and soil type, elevated [CO(2)] consistently decreased water flow (i.e., g(s) and leaf-specific hydraulic conductivity) and total vessel area of the petiole in sun leaves; however, it had no effect on these parameters in shade leaves, perhaps because g(s) of shade leaves was already low. Changes in water flow at elevated [CO(2)] were associated with changes in petiole hydraulic properties. PMID:18055439

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

    SciTech Connect

    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

    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.

  14. Towards high resolution soil property maps for Austria

    NASA Astrophysics Data System (ADS)

    Schürz, Christoph; Klotz, Daniel; Herrnegger, Mathew; Schulz, Karsten

    2015-04-01

    Soil hydraulic properties, such as soil texture, soil water retention characteristics, hydraulic conductivity, or soil depth are important inputs for hydrologic catchment modelling. However, the availability of such data in Austria is often insufficient to fulfill requirements of well-established hydrological models. Either, soil data is available in sufficient spatial resolution but only covers a small extent of the considered area, or the data is comprehensive but rather coarse in its spatial resolution. Furthermore, the level of detail and quality of the data differs between the available data sets. In order to generate a comprehensive soil data set for whole Austria that includes main soil physical properties, as well as soil depth and organic carbon content in a high spatial resolution (10x10 to 100x100m²) several available soil data bases are merged and harmonized. Starting point is a high resolution soil texture map that only covers agricultural areas and is available due to Austrian land appraisal. Soil physical properties for those areas are derived by applying pedotransfer functions (e.g. Saxton and Rawls, 2006) resulting in expectation values and quantiles of the respective property for each soil texture class. For agricultural areas where no texture information is available, the most likely soil texture is assigned applying a Bayesian network approach incorporating information such as elevation, soil slope, soil type, or hydro-geology at different spatial scales. Soil data for forested areas, that cover a large extent of the state territory, are rather sparse in Austria. For such areas a similar approach as for agricultural areas is applied by using a Bayesian network for prediction of the soil texture. Additionally, information to various soil parameters taken from literature is incorporated. For areas that are covered by land use different to agriculture or forestry, such as bare rock surfaces, or wetland areas, solely literature information is used to assign soil physical parameters to the soil data set. Soil depth is only available in a very coarse spatial resolution. By correlating this information with altitude and slope steepness, soil depth data is refined. An evaluation of the Bayesian network predictions will be performed within a cross-validation framework.

  15. HYDRAULIC AND PHYSICAL PROPERTIES OF SALTSTONE GROUTS AND VAULT CONCRETES

    SciTech Connect

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

    2008-11-25

    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.

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

    PubMed Central

    Carminati, Andrea; Vetterlein, Doris

    2013-01-01

    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

  17. 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...

  18. Tillage effects on physical properties in two soils of the Northern Great Plains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tillage practices profoundly affect soil physical and hydraulic properties. It is essential to select a tillage practice that sustains the soil physical properties required for successful growth of agricultural crops. We evaluated the effects of conventional (CT) and strip (ST) tillage practices on ...

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

    E-print Network

    Paris-Sud XI, Université de

    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

  20. Geoelectrical evaluation of soil properties

    NASA Astrophysics Data System (ADS)

    Chitea, F.; Ioane, D.; Kodom, K.

    2009-04-01

    Major efforts are directed lately worldwide in order to establish proper strategies for the preservation of soil quality, its protection and sustainable use. Therefore there is a great interest in finding new techniques able to offer information in real time on the soil properties (porosity, bulk density), compaction, salinity or moisture content. Aiming at getting information on soil properties and relate their spatial modifications to variations of electric resistivity, laboratory analyses have been performed on soil samples taken on several lines. The data obtained on the selected line are presented in the following, as variation ranges: density 2.4 - 2.6 g/cm3; porosity 51 - 79%; moisture content 8 - 20%; electric resistivity 45 - 110 ohm*m. The variations of such physical properties along the soil line showed correlation between resistivity highs and lows of moisture content and porosity. High values of resistivity correlate well with high densities on this particular type of soil, meaning in both cases sectors of low porosity and lack of water. In order to get information on the geoelectric measurements resolution on shallow layers of soil, a soil model have been built for the studied line, the depth between the surface and the depth of 0.63 m being divided in vertical sectors with resistivity contrasts. The electric resistivity values obtained on soil samples have been placed in the corresponding sectors, in order to reproduce the physical conditions on the surveyed line. Resistivity measurements on this line were simulated for different geoelectric techniques: Wenner, Schlumberger, Wenner-Schlumberger and Gradient-Dipole. The results obtained using these techniques consisted in variations of resistivity for the considered soil model. The interpretation of such geoelectric data led to soil models for each employed technique. By comparing these results to the starting soil resistivity model, the capability of these techniques for shallow soil layer investigations has been evaluated.

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

    E-print Network

    Boyer, Edmond

    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

  2. Hydraulics.

    ERIC Educational Resources Information Center

    Decker, Robert L.

    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,…

  3. Measurement of soil saturated hydraulic conductivity: The method of constant pressure tubes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Field method to measure the saturated soil hydraulic conductivity is presented that does not require expensive equipment and preserves natural water flow pathways that may be bloked during soil core sampling for laboratory measurements. Vegetation must be removed from the plot prior the measurement...

  4. The effect of mineral-ion interactions on soil hydraulic conductivity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The reuse of winery wastewater (WW) for irrigation could provide an alternative water source for wine production. The shift of many wineries and other food processing industries to K+-based cleaners requires studies on the effects of K+ on soil hydraulic conductivity (HC). Soils of contrasting mine...

  5. Papermill biosolids effect on soil physical and chemical properties.

    PubMed

    Price, G W; Voroney, R P

    2007-01-01

    Papermill biosolids (PB) can provide multiple benefits to the soil system. The purpose of this study was to quantify the effects of a high C/N ratio (C/N = 100) de-inked PB on soil physical and chemical properties, including soil bulk density, infiltration rates, wet aggregate stability, total soil carbon, and heavy metal concentrations. Four rates of PB (0, 50, 100, and 150 Mg ha(-1)) were applied annually, for up to 3 yr, on four agricultural soils in Ontario, Canada. Decreases in soil bulk density between 0.27 and 0.35 g cm(-3), relative to the nonamended treatment, were observed in soils receiving PB treatments over 3 yr. Total soil carbon increased within 1 yr on PB-amended soils planted to soybeans but not on soils planted to corn. Hydraulic conductivities (K fs) were greater in all soils receiving PB amendments relative to the nonamended treatment throughout the study. Other properties measured, such as pH and electrical conductivity, were relatively unchanged after 2 yr of PB applications. While some increases in heavy metal accumulation occurred, there were no clear trends observed at any of the sites related to PB rates. The results of this study provide support to the idea that annual applications of PB can add significantly to the stability of soil structure. PMID:17940271

  6. Application of Multitemporal Remotely Sensed Soil Moisture for the Estimation of Soil Physical Properties

    NASA Technical Reports Server (NTRS)

    Mattikalli, N. M.; Engman, E. T.; Jackson, T. J.; Ahuja, L. R.

    1997-01-01

    This paper demonstrates the use of multitemporal soil moisture derived from microwave remote sensing to estimate soil physical properties. The passive microwave ESTAR instrument was employed during June 10-18, 1992, to obtain brightness temperature (TB) and surface soil moisture data in the Little Washita watershed, Oklahoma. Analyses of spatial and temporal variations of TB and soil moisture during the dry-down period revealed a direct relationship between changes in T and soil moisture and soil physical (viz. texture) and hydraulic (viz. saturated hydraulic conductivity, K(sat)) properties. Statistically significant regression relationships were developed for the ratio of percent sand to percent clay (RSC) and K(sat), in terms of change components of TB and surface soil moisture. Validation of results using field measured values and soil texture map indicated that both RSC and K(sat) can be estimated with reasonable accuracy. These findings have potential applications of microwave remote sensing to obtain quick estimates of the spatial distributions of K(sat), over large areas for input parameterization of hydrologic models.

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

    NASA Astrophysics Data System (ADS)

    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

    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.

  8. Uncertainty analysis and validation of the estimation of effective hydraulic properties at the Darcy scale

    NASA Astrophysics Data System (ADS)

    Mesgouez, A.; Buis, S.; Ruy, S.; Lefeuve-Mesgouez, G.

    2014-05-01

    The determination of the hydraulic properties of heterogeneous soils or porous media remains challenging. In the present study, we focus on determining the effective properties of heterogeneous porous media at the Darcy scale with an analysis of their uncertainties. Preliminary, experimental measurements of the hydraulic properties of each component of the heterogeneous medium are obtained. The properties of the effective medium, representing an equivalent homogeneous material, are determined numerically by simulating a water flow in a three-dimensional representation of the heterogeneous medium, under steady-state scenarios and using its component properties. One of the major aspects of this study is to take into account the uncertainties of these properties in the computation and evaluation of the effective properties. This is done using a bootstrap method. Numerical evaporation experiments are conducted both on the heterogeneous and on the effective homogeneous materials to evaluate the effectiveness of the proposed approach. First, the impact of the uncertainties of the component properties on the simulated water matric potential is found to be high for the heterogeneous material configuration. Second, it is shown that the strategy developed herein leads to a reduction of this impact. Finally, the adequacy between the mean of the simulations for the two configurations confirms the suitability of the homogenization approach, even in the case of dynamic scenarios. Although it is applied to green roof substrates, a two-component media composed of bark compost and pozzolan used in the construction of buildings, the methodology proposed in this study is generic.

  9. Microwave Remote Sensing of Soil Moisture for Estimation of Soil Properties

    NASA Technical Reports Server (NTRS)

    Mattikalli, Nandish M.; Engman, Edwin T.; Jackson, Thomas J.

    1997-01-01

    Surface soil moisture dynamics was derived using microwave remote sensing, and employed to estimate soil physical and hydraulic properties. The L-band ESTAR radiometer was employed in an airborne campaign over the Little Washita watershed, Oklahoma during June 10-18, 1992. Brightness temperature (TB) data were employed in a soil moisture inversion algorithm which corrected for vegetation and soil effects. Analyses of spatial TB and soil moisture dynamics during the dry-down period revealed a direct relationship between changes in TB, soil moisture and soil texture. Extensive regression analyses were carried out which yielded statistically significant quantitative relationships between ratio of percent sand to percent clay (RSC, a term derived to quantify soil texture) and saturated hydraulic conductivity (Ksat) in terms of change components of TB and surface soil moisture. Validation of results indicated that both RSC and Ksat can be estimated with reasonable accuracy. These findings have potential applications for deriving spatial distributions of RSC and Ksat over large areas.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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).

  11. Effect of subsoiling on soil physical properties and dry matter production on a Brown Soil in Southland, New Zealand

    Microsoft Academic Search

    J. J. Drewry; R. J. Paton

    2000-01-01

    This study examined the effect of shallow subsoiling on soil physical properties and ryegrass?white clover pasture production on a Waikiwi silt loam (Brown Soil) over 2.5 years. Macroporosity, hydraulic conductivity, and air permeability were measured in 6?cm increments down to 30 cm soil depth. The topsoil was loosened by pulling both conventional tines or wing?shaped tines set at 50 cm

  12. A comparative study of multiple approaches to soil hydraulic parameter scaling applied at the hillslope scale

    NASA Astrophysics Data System (ADS)

    Jana, Raghavendra B.; Mohanty, Binayak P.

    2012-02-01

    Soil hydraulic parameters were upscaled from a 30 m resolution to a 1 km resolution using four different aggregation schemes across the Little Washita watershed in Oklahoma. A topography-based aggregation scheme, a simple homogenization method, a Markov chain Monte Carlo (MCMC)-based stochastic technique, and a Bayesian neural network (BNN) approach to the upscaling problem were analyzed in this study. The equivalence of the upscaled parameters was tested by simulating water flow for the watershed pixels in HYDRUS-3-D, and comparing the resultant soil moisture states with data from the electronically scanned thin array radiometer (ESTAR) airborne sensor during the SGP97 hydrology experiment. The watershed was divided into pixels of 1 km resolution and the effective soil hydraulic parameters obtained for each pixel. The domains were then simulated using the physics-based HYDRUS-3-D platform. Simulated soil moisture states were compared across scales, and the coarse scale values compared against the ESTAR soil moisture data products during the SGP97 hydrology experiment period. Results show considerable correlations between simulated and observed soil moisture states across time, topographic variations, location, elevation, and land cover for techniques that incorporate topographic information in their routines. Results show that the inclusion of topography in the hydraulic parameter scaling algorithm accounts for much of the variability. The topography-based scaling algorithm, followed by the BNN technique, were able to capture much of the variation in soil hydraulic parameters required to generate equivalent soil moisture states in a coarsened domain. The homogenization and MCMC methods, which did not account for topographic variations, performed poorly in providing effective soil hydraulic parameters at the coarse scale.

  13. A Topography-Based Scaling Algorithm for Soil Hydraulic Parameters at Hill-slope Scales

    NASA Astrophysics Data System (ADS)

    Mohanty, B. P.; Jana, R. B.

    2010-12-01

    Understanding how soil hydraulic parameter values are affected at different scales by the spatial variability of influencing factors such as soil structure & texture, vegetation, and topography, as also the atmospheric forcings such as precipitation, is an inherent requirement of efficient scaling schemes. While available 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 an upscaling algorithm accounting for topographic controls of the soil hydraulic parameter variations across space was considered necessary. In this study soil hydraulic parameters were upscaled from a 30-m resolution to a 1-km resolution using a new aggregation scheme where the scale parameter was based on the topography. The new upscaling algorithm was tested at the hill-slope 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 physical-based HYDRUS-3D modeling platform. In order to account for the surface (run-off/on) and sub-surface fluxes between pixels, an algorithm to route infiltration-excess run-off 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.

  14. Characterizing hydraulic properties of filter material of a Vertical Flow1 Constructed Wetland2

    E-print Network

    Paris-Sud XI, Université de

    Characterizing hydraulic properties of filter material of a Vertical Flow1 Constructed Wetland2 A Characterizing the hydraulic properties of filter material used in a vertical flow11 constructed wetland (VFCW of porous mineral material and13 organic matter that makes hydraulic characterization a difficult task. Here

  15. Estimating biozone hydraulic conductivity in wastewater soil-infiltration systems using inverse numerical modeling.

    PubMed

    Bumgarner, Johnathan R; McCray, John E

    2007-06-01

    During operation of an onsite wastewater treatment system, a low-permeability biozone develops at the infiltrative surface (IS) during application of wastewater to soil. Inverse numerical-model simulations were used to estimate the biozone saturated hydraulic conductivity (K(biozone)) under variably saturated conditions for 29 wastewater infiltration test cells installed in a sandy loam field soil. Test cells employed two loading rates (4 and 8cm/day) and 3 IS designs: open chamber, gravel, and synthetic bundles. The ratio of K(biozone) to the saturated hydraulic conductivity of the natural soil (K(s)) was used to quantify the reductions in the IS hydraulic conductivity. A smaller value of K(biozone)/K(s,) reflects a greater reduction in hydraulic conductivity. The IS hydraulic conductivity was reduced by 1-3 orders of magnitude. The reduction in IS hydraulic conductivity was primarily influenced by wastewater loading rate and IS type and not by the K(s) of the native soil. The higher loading rate yielded greater reductions in IS hydraulic conductivity than the lower loading rate for bundle and gravel cells, but the difference was not statistically significant for chamber cells. Bundle and gravel cells exhibited a greater reduction in IS hydraulic conductivity than chamber cells at the higher loading rates, while the difference between gravel and bundle systems was not statistically significant. At the lower rate, bundle cells exhibited generally lower K(biozone)/K(s) values, but not at a statistically significant level, while gravel and chamber cells were statistically similar. Gravel cells exhibited the greatest variability in measured values, which may complicate design efforts based on K(biozone) evaluations for these systems. These results suggest that chamber systems may provide for a more robust design, particularly for high or variable wastewater infiltration rates. PMID:17449084

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

    NASA Astrophysics Data System (ADS)

    Jana, Raghavendra B.; Mohanty, Binayak P.

    2012-02-01

    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.

  17. Characterisation of water transmission properties in tilled and untilled soils using tension infiltrometers

    Microsoft Academic Search

    W. D. Reynolds; E. G. Gregorich; W. E. Curnoe

    1995-01-01

    Tension infiltrometer (TI) measurements from a silty clay loam soil (Winchester, Ont.), a sandy soil (Hancock, WI), and a silt loam soil (Rosemount, MN) were used to: (i) characterise near-saturated hydraulic conductivity (K0) and flow-weighted mean radius of soil macropores (R0); (ii) distinguish differences in these water transmission properties between no-till (NT) and mouldboard plough (MP) continuous maize (Zea mays

  18. Using boosted regression trees to predict the near-saturated hydraulic conductivity of undisturbed soils

    NASA Astrophysics Data System (ADS)

    Koestel, John; Bechtold, Michel; Jorda, Helena; Jarvis, Nicholas

    2015-04-01

    The saturated and near-saturated hydraulic conductivity of soil is of key importance for modelling water and solute fluxes in the vadose zone. Hydraulic conductivity measurements are cumbersome at the Darcy scale and practically impossible at larger scales where water and solute transport models are mostly applied. Hydraulic conductivity must therefore be estimated from proxy variables. Such pedotransfer functions are known to work decently well for e.g. water retention curves but rather poorly for near-saturated and saturated hydraulic conductivities. Recently, Weynants et al. (2009, Revisiting Vereecken pedotransfer functions: Introducing a closed-form hydraulic model. Vadose Zone Journal, 8, 86-95) reported a coefficients of determination of 0.25 (validation with an independent data set) for the saturated hydraulic conductivity from lab-measurements of Belgian soil samples. In our study, we trained boosted regression trees on a global meta-database containing tension-disk infiltrometer data (see Jarvis et al. 2013. Influence of soil, land use and climatic factors on the hydraulic conductivity of soil. Hydrology & Earth System Sciences, 17, 5185-5195) to predict the saturated hydraulic conductivity (Ks) and the conductivity at a tension of 10 cm (K10). We found coefficients of determination of 0.39 and 0.62 under a simple 10-fold cross-validation for Ks and K10. When carrying out the validation folded over the data-sources, i.e. the source publications, we found that the corresponding coefficients of determination reduced to 0.15 and 0.36, respectively. We conclude that the stricter source-wise cross-validation should be applied in future pedotransfer studies to prevent overly optimistic validation results. The boosted regression trees also allowed for an investigation of relevant predictors for estimating the near-saturated hydraulic conductivity. We found that land use and bulk density were most important to predict Ks. We also observed that Ks is large in fine and coarse textured soils and smaller in medium textured soils. Completely different predictors were important for appraising K10, where the soil macropore system is air-filled and therefore inactive. Here, the average annual temperature and precipitation where most important. The reasons for this are unclear and require further research. The clay content and the organic matter content were also important predictors of K10. We suggest that a larger and more complete database may help to improve the prediction of K10, whereas it may be more fruitful to estimate Ks statistics of sampling sites instead of individual values since the Ks is highly variable over very short distances.

  19. A New Perspective on Soil Thermal Properties

    Microsoft Academic Search

    Tyson E. Ochsner; Robert Horton; Tusheng Ren

    2001-01-01

    fractions of soil water, solids, and air. Table 1 does not include experiments using pure sand, crushed rock, The soil thermal properties—heat capacity (C ), thermal diffusivity gravel, or peat, all of which may have thermal properties (), and thermal conductivity ()—are important in many agricultural, engineering, and meteorological applications. Soil thermal properties drastically different from most soils. The research

  20. Sask method for testing hydraulic conductivity of soils by flat dilatometer (dmt)

    NASA Astrophysics Data System (ADS)

    Garbulewski, Kazimierz; ?akowicz, Stanis?aw; Rabarijoely, Simon; ?ada, Anna

    2012-10-01

    DMT is one of the most popular methods of determining soil parameters needed to design a safe construction. Apart from the basic outcome parameter obtained from DMT measurements hydraulic conductivity (k) can be determined, previously proposed DMTA and DMTC methods were modified. The basic idea of the method is that the return of the deformed membrane is due to soil and water pressure. In the proposed SASK method the hydraulic conductivity of the soil is determined by measuring time-varying pressures A and C. Research has been performed at the experimental site of the Department of Geotechnical Engineering, WULS. In the paper, the assumptions of the new method for determining the hydraulic conductivity k are presented. The proposed method allows us to determine a reliable value for the hydraulic conductivity of clay soils. Using this method, the value of hydraulic conductivity (k = 5,47*10-11) is similar to the results of BAT, DMTA and laboratory measurements.

  1. Phoenix soil physical properties investigation

    NASA Astrophysics Data System (ADS)

    Shaw, Amy; Arvidson, Raymond E.; Bonitz, Robert; Carsten, Joseph; Keller, H. U.; Lemmon, Mark T.; Mellon, Michael T.; Robinson, Matthew; Trebi-Ollennu, Ashitey

    2009-12-01

    The Phoenix Lander investigated the polygonal terrain and associated soil and icy soil deposits of a high northern latitude site on Mars. The soil physical properties component involved the analysis of force data determined from motor currents from the Robotic Arm (RA)'s trenching activity. Using this information and images of the landing site, soil cohesion and angle of internal friction were determined. Dump pile slopes were used to determine the angle of internal friction of the soil: 38° ± 5°. Additionally, an excavation model that treated walls and edges of the scoop as retaining walls was used to calculate mean soil cohesions for several trenches in the Phoenix landing site workspace. These cohesions were found to be consistent with the stability of steep trench slopes. Cohesions varied from 0.2 ± 0.4kPa to 1.2 ± 1.8 kPa, with the exception of a subsurface platy horizon unique to a shallow trough for which cohesion will have to be determined using other methods. Soil on polygon mounds had the greatest cohesion (1.2 ± 1.8 kPa). This was most likely due to the presence of adsorbed water or pore ice above the shallow icy soil surface. Further evidence for enhanced cohesion above the ice table includes lateral increase in excavation force, by over 30 N, as the RA approached ice.

  2. Estimation of field-scale soil hydraulic and dielectric parameters through joint inversion of GPR and hydrological data

    E-print Network

    Hubbard, Susan

    . Introduction [2] Ground-penetrating radar (GPR) measurements are not directly related to soil hydraulicEstimation of field-scale soil hydraulic and dielectric parameters through joint inversion of GPR November 2005. [1] A method is described for the joint use of time-lapse ground-penetrating radar (GPR

  3. 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.

  4. Spatial Bias in Field-Estimated Unsaturated Hydraulic Properties

    SciTech Connect

    HOLT,ROBERT M.; WILSON,JOHN L.; GLASS JR.,ROBERT J.

    2000-12-21

    Hydraulic property measurements often rely on non-linear inversion models whose errors vary between samples. In non-linear physical measurement systems, bias can be directly quantified and removed using calibration standards. In hydrologic systems, field calibration is often infeasible and bias must be quantified indirectly. We use a Monte Carlo error analysis to indirectly quantify spatial bias in the saturated hydraulic conductivity, K{sub s}, and the exponential relative permeability parameter, {alpha}, estimated using a tension infiltrometer. Two types of observation error are considered, along with one inversion-model error resulting from poor contact between the instrument and the medium. Estimates of spatial statistics, including the mean, variance, and variogram-model parameters, show significant bias across a parameter space representative of poorly- to well-sorted silty sand to very coarse sand. When only observation errors are present, spatial statistics for both parameters are best estimated in materials with high hydraulic conductivity, like very coarse sand. When simple contact errors are included, the nature of the bias changes dramatically. Spatial statistics are poorly estimated, even in highly conductive materials. Conditions that permit accurate estimation of the statistics for one of the parameters prevent accurate estimation for the other; accurate regions for the two parameters do not overlap in parameter space. False cross-correlation between estimated parameters is created because estimates of K{sub s} also depend on estimates of {alpha} and both parameters are estimated from the same data.

  5. Application of In-situ Lysimetric Studies for Determining Soil Hydraulic Conductivity

    Microsoft Academic Search

    B. Hanumantha Rao; V. Sridhar; R. R. Rakesh; D. N. Singh; P. K. Narayan; P. K. Wattal

    2009-01-01

    Several techniques such as laboratory column studies, under normal and accelerated gravity environments, numerical modeling\\u000a and pedo-transfer functions have been employed by previous researchers to determine hydraulic conductivity of soils. However,\\u000a these methods suffer with several limitations, particularly, as far as regeneration of in-situ soil conditions and boundary\\u000a conditions, in an exceptionally small model, are concerned. Under these circumstances, in-situ

  6. 1 Estimating aquifer hydraulic properties from the inversion of surface 2 Streaming Potential (SP) anomalies

    E-print Network

    Sailhac, Pascal

    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

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

    E-print Network

    Peirce, Anthony

    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

  8. An insight into the role of hydraulic history on the volume changes of anisotropic clayey soils

    NASA Astrophysics Data System (ADS)

    Romero, Enrique; Jommi, Cristina

    2008-05-01

    Volume changes of natural and compacted soils induced by changes in their water content have many practical implications in the service life of earth dams, river and canal embankments, and waste disposal facilities. An insight into the overall strain response of a clayey soil upon gradual wetting and drying is provided here. Experimental data coming from oedometer and isotropic tests under suction and net stress control are presented for a compacted clay with an initial anisotropic fabric, highlighting the relevant role played by the hydraulic path on collapse, swelling, and shrinkage strains. Irreversible strains could be observed after wetting-drying paths and the subsequent drying-wetting cycle. Both stress and hydraulic histories play a role in the evolution of the directional fabric of clayey soils. The experimental data could be reproduced with a rather simple elastic-plastic constitutive model with a mixed isotropic-rotational hardening, previously conceived for saturated soils. The model is extended to unsaturated conditions by substituting the saturated effective stress with a measure of the average stress acting on the soil skeleton and by introducing generalized hardening rules governed by both plastic strains and degree of saturation. Coupling between the mechanical and the hydraulic behavior is provided by the water retention curve, in which degree of saturation is adopted as a useful measure of the soil water content.

  9. EFFECTS OF ROCK FRAGMENTS INCORPORATED IN THE SOIL MATRIX ON CONCENTRATED FLOW HYDRAULICS AND EROSION 1836

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rock fragments can act as a controlling factor for erosional rates and patterns in the landscape. Thus, the objective of this study is to better understand the role that rock fragments incorporated into the soil matrix have on concentrated flow hydraulics and erosion . Laboratory flume experiments...

  10. Effect of spatial variability of soil properties on infiltration

    NASA Astrophysics Data System (ADS)

    Domenech, Marisa; Castro Franco, Mauricio; Aparicio, Virginia; Costa, José Luis

    2013-04-01

    Topography and soil properties are key determinants of spatial variability of water content. Prediction of soil hydraulic properties are essential for modeling water flow and solute transport. In the southeastern of Buenos Aires Province, the effect of the relief on soil spatial variability is result of the relationship between elevation and effective depth (ED). Digital elevation models (DEM) provide quantitive information about relief. The objective was to determine the effect of spatial variability of soil properties on infiltration. The field was 50 ha and the soil classes were vertic Hapludoll, typic and petrocalcic Argiudoll. ED was measured using Gidding_Soil_Sampler® in 30x30m grid size. Elevation data were measured ussing a DGPS Trimble_R3®. From this, a DEM was generated. Two elevation and ED areas were delineated named High and Low zones. Three soil samples were taken at each zone with three replications at depth 0-30 and 30-90 cm. Texture, bulk density (?b) and organic matter (OM) were determined. A disc infiltrometer was used to determine the water infiltration rate (i). Clay content (As) and OM were homogeneous in the profile of the High zone. However, As content at 30-90 cm decreased in the Low zone. At the High zone, ?b ranged from 1.31 to 1.34 g cm-3 and was higher than at the Low zone (?b=1.16 - 1.27 g cm-3). Also the i had less variation at the High zone. Under pressure head of -1 cm , the i increased in the Low zone. At lower pressure heads, the i was greater in the High zone. Higher i at the Low zone could be due to major ED, textural heterogeneity and higher OM content. Textural homogeneity, shallow ED and high ?b allowed a more stable i at the High zone. Using topography and ED is a promising way of characterizing soil hydraulic behavior and its spatial variability across a field.

  11. Temporal variability of selected chemical and physical properties of topsoil of three soil types

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    Temporal variability of soil properties measured in surface horizons of three soil types (Haplic Cambisol, Greyic Phaeozem, Haplic Luvisol) was studied in years 2007, 2008, 2009 and 2010. Undisturbed soil samples were taken every month to evaluate the actual field soil-water content, bulk density, porosity and hydraulic properties. The grab soil samples were taken every month to evaluate aggregate stability using the WSA (water stable aggregates) index, pHH2O and pHKCl, soil organic matter content and quality. Unsaturated hydraulic conductivity for pressure head of -2 cm was measured directly in the field using the minidisk tension infiltrometer. In addition soil structure was documented on micromorphological images. In some cases, the similar trends of the pHH2O , pHKCl , A400/A600, rod, P, ?field or WSA values were observed in different soils. Interestingly, the similar trends were found mostly for the Haplic Cambisol and the Greyic Phaeozem despite the fact that these soils considerably differed (different soil substrate, pedogenetic processes, etc.) and that variable crops (winter wheat and spring wheat) were planted at both locations during two years (2007 and 2006). Mostly different trends were observed for the Haplic Luvisol and the Greyic Phaeozem (soil of the same substrate). The reason could be attributed to a high vulnerability of the Haplic Luvisol to soil degradation in comparison to that of the Greyic Phaeozem. Parameters of hydraulic properties were highly variable and did not show similar trends for different soils (except the saturated soil water content and the slope of the retention curve at the inflection point for Haplic Cambisol and Greyic Phaeozem). Soil structure, aggregate stability and soil hydraulic properties were interrelated and depended on plant growth, rainfall compaction and tillage. The drier conditions in some soils positively influenced the soil aggregate stability, the slope of the retention curve at the inflection point and hydraulic conductivity. Probably due to the high variation of soil hydraulic properties no closer correlation between them and other properties was detected. Despite that the slope of the retention curve at the inflection point (which should indicate physical quality of the soil, e.g. soil aggregation and consequently soil porosity system) in many cases increased (decreased) when also the soil aggregate stability and hydraulic conductivity values increased (decreased), no closer correlation was revealed when analyzing for the entire 4 year period. The study showed different trends during different years. This was anticipated in the Greyic Phaeozem where different cops (spring wheat, winter wheat and winter barley) were planted during different years. Different trends were however observed also in the Haplic Cambisol and the Haplic Luvisol, where the same or similar crops (in both cases mostly winter wheat and ones winter barley) was sown. Results showed that climatic conditions (mostly during he winter end spring) played dominant role. Thus data, which were obtained during one year period, could not be used to generalize a soil regime in a particular soil and crop. Our results showed that it is impossible to apply any model, which would be based on statistical analyses, to predict soil properties development during one year or even longer period. Results indicate that findings cannot be used to generalize soil properties for other soil types, plants or climates. Acknowledgment: Authors acknowledge the financial support of the Czech Science Foundation (GA CR 526/08/0434) and the Ministry of Agriculture of the Czech Republic (QJ1230319).

  12. Mechanical and hydraulic properties of rocks related to induced seismicity

    USGS Publications Warehouse

    Witherspoon, P.A.; Gale, J.E.

    1977-01-01

    Witherspoon, P.A. and Gale, J.E., 1977. Mechanical and hydraulic properties of rocks related to induced seismicity. Eng. Geol., 11(1): 23-55. The mechanical and hydraulic properties of fractured rocks are considered with regard to the role they play in induced seismicity. In many cases, the mechanical properties of fractures determine the stability of a rock mass. The problems of sampling and testing these rock discontinuities and interpreting their non-linear behavior are reviewed. Stick slip has been proposed as the failure mechanism in earthquake events. Because of the complex interactions that are inherent in the mechanical behavior of fractured rocks, there seems to be no simple way to combine the deformation characteristics of several sets of fractures when there are significant perturbations of existing conditions. Thus, the more important fractures must be treated as individual components in the rock mass. In considering the hydraulic properties, it has been customary to treat a fracture as a parallel-plate conduit and a number of mathematical models of fracture systems have adopted this approach. Non-steady flow in fractured systems has usually been based on a two-porosity model, which assumes the primary (intergranular) porosity contributes only to storage and the secondary (fracture) porosity contributes only to the overall conductivity. Using such a model, it has been found that the time required to achieve quasi-steady state flow in a fractured reservoir is one or two orders of magnitude greater than it is in a homogeneous system. In essentially all of this work, the assumption has generally been made that the fractures are rigid. However, it is clear from a review of the mechanical and hydraulic properties that not only are fractures easily deformed but they constitute the main flow paths in many rock masses. This means that one must consider the interaction of mechanical and hydraulic effects. A considerable amount of laboratory and field data is now available that clearly demonstrates this stress-flow behavior. Two approaches have been used in attempting to numerically model such behavior: (1) continuum models, and (2) discrete models. The continuum approach only needs information as to average values of fracture spacing and material properties. But because of the inherent complexity of fractured rock masses and the corresponding decrease in symmetry, it is difficult to develop an equivalent continuum that will simulate the behavior of the entire system. The discrete approach, on the other hand, requires details of the fracture geometry and material properties of both fractures and rock matrix. The difficulty in obtaining such information has been considered a serious limitation of discrete models, but improved borehole techniques can enable one to obtain the necessary data, at least in shallow systems. The possibility of extending these methods to deeper fracture systems needs more investigation. Such data must be considered when deciding whether to use a continuum or discrete model to represent the interaction of rock and fluid forces in a fractured rock system, especially with regard to the problem of induced seismicity. When one is attempting to alter the pressure distribution in a fault zone by injection or withdrawal of fluids, the extent to which this can be achieved will be controlled in large measure by the behavior of the fractures that communicate with the borehole. Since this is essentially a point phenomenon, i.e., the changes will propagate from a relatively small region around the borehole, the use of a discrete model would appear to be preferable. ?? 1977.

  13. Simulating runoff from an area covered by soil contour ridges using a hydraulic cascade model

    NASA Astrophysics Data System (ADS)

    Slah, Nasri

    2015-04-01

    Runoff agriculture and rainwater harvesting are well known farming techniques that have guaranteed crop production in the arid zone of Tunisia since ancient times. At present, soil contour ridges (banquettes) are the main water and soil conservation used. Actually about one million ha farming land were protected by this technique. Usually, soil contour ridges are designed for a 10-year return period to reduce runoff and erosion in hill-slope catchments. However, the detailed hydraulic function of this technique is still to a major extent unknown. For this purpose a runoff model was developed to simulate the discharge from an upstream system of several soil contour ridges. The model was validated using experimental runoff. The simulated runoff agreed well with observed discharge. The validated model was used to simulate runoff from a system of one to several soil contour ridges in a cascade from a 10-year rainfall event. Practical conclusions are drawn by discussing the spacing and design of the soil contour ridges. Key words: Soil surface management, soil contour ridge, discharge, hydraulic cascade.

  14. Hydraulic fracturing to enhance the remediation of DNAPL in low permeability soils

    SciTech Connect

    Murdoch, L. [Univ. of Cincinnati, OH (United States); Slack, B. [FRX Inc., Cincinnati, OH (United States)

    1996-08-01

    Meager rates of fluid flow are a major obstacle to in situ remediation of low permeability soils. This paper describes methods designed to avoid that obstacle by creating fractures and filling them with sand to increase well discharge and change paths of fluid flow in soil. Gently dipping fractures 10 m in maximum dimension and 1 to 2 cm thick can be created in some contaminated soils at depths of a few in or greater. Hydraulic fractures can also be used to create electrically conductive layers or to deliver granules of chemically or biologically active compounds that will degrade contaminants in place. Benefits of applying hydraulic fractures to DNAPL recovery include rates of fluid recovery, enhancing upward gradients to improve hydrodynamic stabilization, forming flat-lying reactive curtains to intersect compounds moving downward, or improving the performance of electrokinetics intended to recover compounds dissolved in water. 30 refs., 7 figs., 1 tab.

  15. Soil property effects on wind erosion of organic soils

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

    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.

  16. Pharmaceuticals' sorptions relative to properties of thirteen different soils.

    PubMed

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

    2015-04-01

    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

  17. A transient laboratory method for determining the hydraulic properties of 'tight' rocks-II. Application

    USGS Publications Warehouse

    Neuzil, C.E.; Cooley, C.; Silliman, S.E.; Bredehoeft, J.D.; Hsieh, P.A.

    1981-01-01

    In Part I a general analytical solution for the transient pulse test was presented. Part II presents a graphical method for analyzing data from a test to obtain the hydraulic properties of the sample. The general solution depends on both hydraulic conductivity and specific storage and, in theory, analysis of the data can provide values for both of these hydraulic properties. However, in practice, one of two limiting cases may apply in which case it is possible to calculate only hydraulic conductivity or the product of hydraulic conductivity times specific storage. In this paper we examine the conditions when both hydraulic parameters can be calculated. The analyses of data from two tests are presented. In Appendix I the general solution presented in Part I is compared with an earlier analysis, in which compressive storage in the sample is assumed negligible, and the error in calculated hydraulic conductivity due to this simplifying assumption is examined. ?? 1981.

  18. 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)

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

    2014-05-01

    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.

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

    SciTech Connect

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

    2007-02-01

    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.

  20. 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...

  1. SATURATED HYDRAULIC CONDUCTIVITY OF SEMI-ARID SOILS: COMBINED EFFECTS OF SALINITY, SODICITY AND RATE OF WETTING

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Combined effects of soil conditions (wetting rate), soil sodicity and salinity on soil saturated hydraulic conductivity (HC) have not been studied systematically and were the objective of our study. We examined the effects of (i) exchangeable sodium percentage (ESP, 1-20) and fast wetting (50 mm h-1...

  2. In situ bioremediation of petroleum in tight soils using hydraulic fracturing

    SciTech Connect

    Stavnes, S. [Environmental Protection Agency, Denver, CO (United States); Yorke, C.A. [Foremost Solutions, Inc., Golden, CO (United States); Thompson, L. [Pintail Systems, Inc., Aurora, CO (United States)

    1996-12-31

    This case study evaluated the effectiveness of in situ bioremediation of petroleum hydrocarbons in tight soils. The study area was contaminated with cutting oil from historic releases from underground piping, probably dating back to the 1940`s. Previous site assessment work indicated that the only chemicals of concern were total petroleum hydrocarbons (TPH). Two fracture sets (stacks) were installed at different locations to evaluate this in situ bioremediation technique under passive and active conditions. Several injection wells were drilled at both locations to provide entry for hydraulic fracturing equipment. A series of circular, horizontal fractures 40 to 50 feet in diameter were created at different depths, based on the vertical extent of contamination at the site. The injection wells were screened across the contaminated interval which effectively created underground bioreactors. Soils were sampled and analyzed for total petroleum hydrocarbons on five separate occasions over the nine-month study. Initial average soil concentrations of total petroleum hydrocarbons of 5,700 mg/kg were reduced to 475 mg/kg within nine months of hydraulic fracturing. The analytical results indicate an average reduction in TPH at the sample locations of 92 percent over the nine-month study period. This project demonstrates that in situ bioremediation using hydraulic fracturing has significant potential as a treatment technology for petroleum contaminated soils.

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

    E-print Network

    Holbrook, N. Michele

    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

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

    Microsoft Academic Search

    Abrigo

    1996-01-01

    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

  5. Soil hydraulic properties and their effect on surface and subsurface water transfer in a tropical rainforest catchment \\/ Propriétés hydrauliques du sol et leur effet sur les transferts d'eau de surface ou hypodermique dans un bassin de forêt en zone tropicale humide

    Microsoft Academic Search

    M. BONELL; D. A. GILMOUR; D. F. SINCLAIR

    1981-01-01

    This paper examines spatial and temporal heterogeneity of the surface, subsurface and vertical drainage components within and between three sites in a 25.7 ha tropical rainforest catchment. Our analysis indicates that saturation overland flow depends on the relationships between temporal variations in rainfall intensity, the upper soil store capacity, and the spatial variation of saturated hydraulic conductivity in the subsoil

  6. Post-fire Changes in Air Permeability and Hydraulic Conductivity of Soils Following 2003 Aspen Fire in Sabino Canyon, AZ

    NASA Astrophysics Data System (ADS)

    Chief, K.; Ferre, T. P.; Nijssen, B.

    2006-12-01

    As part of a project to study the hydrologic effects of fire on the Sabino Canyon Watershed, the Soil Corer Air Permeameter (SCAP) was developed to rapidly measure in-situ air permeability (k_a) of unburned and burned desert soils while providing a standard soil sample for additional laboratory analysis. Twenty-two unburned and burned plots were selected in woodland-chaparral and coniferous zones with low and high slopes, and low, medium, and high fuel loads or burn severities. Air permeability was measured on a 25-point square grid on each 100 m2 plot (n=445). Hydraulic conductivity (Ksat), water permeability (k_w), soil physical properties, and hydrophobicity measurements were made on extracted soil samples in the laboratory. There was a slight decrease in the median k_a from 95 to 80 ?m2 for the woodland- chaparral zone as a result of the wildfire. There was a greater decrease for the coniferous zone where the median decreased from 152 to 110 ?m2 following the fire. The k_w of woodland-chaparral soils increased from 192 to 425 ?m2; but the median k_w decreased for the coniferous zone from 862 to 444 ?m2 after the fire. In addition, hydrophobic measurements show that there was a significant increase in hydrophobicity for post-fire woodland-chaparral soils but not for coniferous soils. The log k_a and log Ksat measurements were highly correlated for the unburned woodland-chaparral soils, but this correlation decreased for burned woodland-chaparral soils. The unburned coniferous data set had the least k_a and Ksat correlation, but was reasonable for burned coniferous soils. The decrease in correlation may be due to increases of hydrophobicity, uneven wetting and preferential flow in Ksat measurements, or extremely rocky terrain. However, the overall, log k_a-log Ksat correlation for all unburned and burned soils including previous measurements on agricultural and alluvial soils follow the trend of the Iversen et al. (2001) log k_a-log Ksat correlation.

  7. Effects of biochar amendment on geotechnical properties of landfill cover soil.

    PubMed

    Reddy, Krishna R; Yaghoubi, Poupak; Yukselen-Aksoy, Yeliz

    2015-06-01

    Biochar is a carbon-rich product obtained when plant-based biomass is heated in a closed container with little or no available oxygen. Biochar-amended soil has the potential to serve as a landfill cover material that can oxidise methane emissions for two reasons: biochar amendment can increase the methane retention time and also enhance the biological activity that can promote the methanotrophic oxidation of methane. Hydraulic conductivity, compressibility and shear strength are the most important geotechnical properties that are required for the design of effective and stable landfill cover systems, but no studies have been reported on these properties for biochar-amended landfill cover soils. This article presents physicochemical and geotechnical properties of a biochar, a landfill cover soil and biochar-amended soils. Specifically, the effects of amending 5%, 10% and 20% biochar (of different particle sizes as produced, size-20 and size-40) to soil on its physicochemical properties, such as moisture content, organic content, specific gravity and pH, as well as geotechnical properties, such as hydraulic conductivity, compressibility and shear strength, were determined from laboratory testing. Soil or biochar samples were prepared by mixing them with 20% deionised water based on dry weight. Samples of soil amended with 5%, 10% and 20% biochar (w/w) as-is or of different select sizes, were also prepared at 20% initial moisture content. The results show that the hydraulic conductivity of the soil increases, compressibility of the soil decreases and shear strength of the soil increases with an increase in the biochar amendment, and with a decrease in biochar particle size. Overall, the study revealed that biochar-amended soils can possess excellent geotechnical properties to serve as stable landfill cover materials. PMID:25898984

  8. 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

    Adams, Amy Lynn

    2011-01-01

    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 ...

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

    PubMed

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

    2014-07-01

    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

  10. Quantifying the impact of livestock grazing on soil physical properties

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

  11. Communicating soil property variability in heterogeneous soil mapping units

    NASA Astrophysics Data System (ADS)

    Farewell, Timothy

    2014-05-01

    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.

  12. An aerodynamic approach in soil hydraulic conductivity estimation for investigating soil erosion degree

    NASA Astrophysics Data System (ADS)

    Sergey, V.; Vyacheslav, S.

    2015-03-01

    We propose a new method for determining the degree of erosion for zonal soils of the East European Plain. This new approach uses soil porosity and filtration to determine a coefficient of aerodynamic similarity. We evaluated the degree of soil erosion on ranges of the major zonal soils of the eastern part of European Russia by applying this new method. Based on these data, we developed a diagnostic scale to determine the extent of soil erosion in this area.

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

    SciTech Connect

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

    1995-08-01

    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.

  14. Passive characterization of hydrofracture properties using signals from hydraulic pumps

    Microsoft Academic Search

    James W Rector; Qicheng Dong; Tad W Patzek

    2000-01-01

    Massive hydraulic fracturing is used to enhance production from the low-permeability diatomite fields of Kern County, CA. Although critical for designing injection and recovery well patterns, the in-situ hydraulic fracture geometry is poorly understood. In 1990, Shell conducted an extensive seismic monitoring experiment on several hydrofractures prior to a steam drive pilot to characterize hydrofracture geometry. The seismic data were

  15. Passive characterization of hydrofracture properties using signals from hydraulic pumps

    Microsoft Academic Search

    James W. Rector; Q. Dong; T. W. Patzek

    1999-01-01

    Massive hydraulic fracturing is used to enhance production from the low-permeability diatomite fields of Kern County, CA. Although critical for designing injection and recovery well patterns, the in-situ hydraulic fracture geometry is poorly understood. In 1990, Shell conducted an extensive seismic monitoring experiment on several hydrofractures prior to a steam drive pilot to characterize hydrofracture geometry. The seismic data were

  16. 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

  17. Soil Moisture Constants and Physical Properties

    E-print Network

    Standiford, Richard B.

    constants. This paper reports the results of these analyses. Methods and Procedures At each sampling site scientist of the U.S. Soil Con- servation Service. Bulk samples composited from three locations within a 21Soil Moisture Constants and Physical Properties of Selected Soils in Hawaii Teruo Yamamoto U S

  18. Characterization of soil micromorphology using X-ray computed tomography for predicting saturated hydraulic conductivity

    NASA Astrophysics Data System (ADS)

    Elliot, Thomas Ross

    New and cross-disciplinary analytical methods are developed and tested for investigation of intact soil micromorphology, the results of which are applied in established fluid models that, classically, rely on indirect measurement of soil microstructure. The developed methods establish a set of requirements for legitimate application of X-ray Computed Tomography (CT) to intact soil, wherein the acquired CT digital image volumes were validated as representing soil structure through a comparison to classic thin section optical spectrum analytic techniques. The established requirements include: three dimensional (3D) post-acquisition processing of CT imagery, which is demonstrated to retain spatial relationships between discrete soil structures; an objective method of segmenting CT imagery into discrete structures that incorporates both the numerical digital number Hounsfield Unit (HU) and the spatial context; and, the use of 3D quantification methods for measurement of discrete soil structures. Application of the developed processing, segmentation and quantification methods to CT data is utilized in the fulfillment of a series of established and novel saturated hydraulic conductivity (Ks) models. A correlation between the laboratory measured Ks and the CT derived prediction of Ks, via the novel methodology presented, indicates that the direct quantification of soil micromorphology has potential application in future pedologic and fluid dynamics research.

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

    SciTech Connect

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

    1989-01-01

    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.

  20. Challenges associated with sampling dynamic soil properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The determination of dynamic soil properties (DSPs) for agricultural practices poses significant challenges, particularly in the context of values derived as part of the National Soil Survey. Although DSPs have been defined as those properties that change over human time scales, limits on the time ...

  1. Soil processes and properties that distinguish ecological sites and states

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Differences in ecological sites, and sometimes ecological states, are ultimately due to differences in soil properties and processes within a climatic zone. Soil properties are features of a soil, such as soil texture or soil depth. Soil processes are a series of actions in the soil that bring abou...

  2. The influence of arbuscular mycorrhizal colonization on soil-root hydraulic conductance in Agrostis stolonifera L. under two water regimes.

    PubMed

    Gonzalez-Dugo, Victoria

    2010-08-01

    The hypothesis that mycorrhizal colonization improves the soil-root conductance in plants was experimentally tested in a growth chamber using pot cultures of Agrostis stolonifera L. colonized by Glomus intraradices. Plants were grown in 50-l pots filled with autoclaved sand/silt soil (1:1), with and without the mycorrhizal fungus. Within the mycorrhizal treatment, half of the pots remained well watered, while the other half was subjected to a progressive water deficit. Soil water potential (estimated as plant water potential measured at the end of the dark period), xylem water potential measured at the tiller base, transpiration rate, and soil water content were monitored throughout the experiment. Soil-root hydraulic conductance was estimated as the ratio between the instantaneous transpiration rate and the soil and xylem water potential difference. To obtain cultures with similar nutritional status, the P in the modified Hoagland's nutrient solution was withheld from the inoculated pots and applied only once a month. Even though there were no differences on growth or nutrient status for the mycorrhizal treatments, water transport was enhanced by the inoculum presence. Transpiration rate was maintained at lower xylem water potential values in the presence of mycorrhizae. The analysis of the relationship between soil-root hydraulic resistance and soil water content showed that mycorrhizal colonization increased soil-root hydraulic conductance as the soil dried. For these growing conditions, this effect was ascribed to the range of 6-10%. PMID:20049617

  3. 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

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

    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

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

    USGS Publications Warehouse

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

    1996-01-01

    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.

  5. Estimation and spatialization of soil properties through infiltration experiments over the Kairouan plain (center of Tunisia)

    NASA Astrophysics Data System (ADS)

    Shabou, Marouen; Mougenot, Bernard; Lili Chabaane, Zohra; Boulet, Gilles; Ben Aissa, Nadhira; Zribi, Mehrez

    2013-04-01

    Studying soil hydrological processes requires the determination of soil hydraulic parameters whose assessment using traditional methods is expensive and time-consuming. In this paper, our objective is to estimate soil properties at local scale and then to spatialize values across our study site (the Kairouan plain). It is situated in central Tunisia (9° 30'E-10° 15'E, 35° N, 35° 45'N). The climate in this region is semi-arid, with an average annual rainfall of approximately 300 mm per year, Characterized by a rainy season lasting from October to May, with the two rainiest months being October and March. To overcome difficulties encountered by the classical models for the characterization of hydraulic parameters, we have used the simple Beerkan estimation of soil parameters method (BEST). It relies on the particle-size analysis, dry bulk density and simple infiltration tests in cylinders. Furthermore, it facilitates the determination of both the water retention curve, and the hydraulic conductivity curve, defined by their shape and scale parameters. Shape parameters depend on soil texture and derived from particle-size data. Scale parameters are derived from infiltration experiments at null pressure head. Saturated water content is measured directly at the end of infiltration. Hydraulic conductivity and water pressure scale parameters are calculated from the steady-state infiltration rate and prior estimation of sorptivity (S). This is obtained by fitting transient infiltration data on analytical models of infiltration. The selected analytical model was compared with other infiltration equations to estimate Sorptivity and hydraulic conductivity from infiltration modeling data. We derived from these experiments local pedotransfer functions to estimate hydraulic conductivity, welting point and field capacity. These values will be assigned to the center of the FAO textural classes. Spatialization of soil hydrodynamic properties was based on the imprecise existing textural soil map and with local texture modification by floods. The first step consists in producing textural soil maps by merging soil units, identified from previous studies, and typical profiles analysis. For complex soil units, remote sensing and auxiliary data was used (geology, geomorphology, and digital elevation model). Furthermore, a large time series Landsat TM images was used for mapping fields of bare soil based on color and clay fraction indices. Validation over the selected fields was done by a spectral radiometer. In addition, we will try to combine optical and radar remote sensing data with the use of time series TERRASAR over a small region. This method will allow the monitoring of the differential soil surface drying to invert textural classes. A comparison with results obtained from Landsat TM imagery will be done.

  6. The Influence of Glass Leachate on the Hydraulic, Physical, Mineralogical and Sorptive Properties of Hanford Sediment

    SciTech Connect

    Kaplan, Daniel I.; Serne, R. Jeffrey; Schaef, Herbert T.; Lindenmeier, Clark W.; Parker, Kent E.; Owen, Antionette T.; McCready, David E.; Young, James S.

    2003-08-26

    The Immobilized Low Activity Waste (ILAW) generated from the Hanford Site will be disposed of in a vitrified form. It is expected that leachate from the vitrified waste will have a high pH and high ionic strength. The objective of this study was to determine the influence of glass leachate on the hydraulic, physical, mineralogical, and sorptive properties of Hanford sediments. Our approach was to put solutions of NaOH, a simplified surrogate for glass leachate, in contact with quartz sand, a simplified surrogate for the Hanford subsurface sediment, and Warden soil, an actual Hanford sediment. Following contact with three different concentrations of sodium hydroxide solutions, changes in hydraulic conductivity, porosity, moisture retention, mineralogy, aqueous chemistry, and soil-radionuclide distribution coefficients were determined. Under chemical conditions approaching the most caustic glass leachate conditions predicted in the near-field of the ILAW disposal site, approximated by 0.3 M NaOH, significant changes in mineralogy were observed. The clay minerals of the Hanford sediment evidenced the greatest dissolution thereby increasing the relative proportions of the more resistant minerals, e.g., quartz, feldspar, and calcite, in the remaining mass. Some re-precipitation of solids (mostly amorphous gels) was observed after caustic contact with both solids; these precipitates increased the moisture retention in both sediments, likely because of water retained within the gel coatings. The hydraulic conductivities were slightly lower but, because of experimental artifacts, these reductions should not be considered significant. Thus, there does not seem to be large differences in the hydraulic properties of the quartz sand or Warden silt loam soil after 192 days of contact with caustic fluids similar to glass leachate. The long term projected impact of the increased moisture retention has not been evaluated but likely will not make past simplified performance projections invalid. Despite the fact that some clay minerals, smectites and kaolinite, almost totally dissolved within a year of contact with 3.0 M NaOH (and by inference after longer time frames for 0.3 M NaOH, a more realistic surrogate for ILAW glass leachate) other sorbing minerals such as illite and chlorite do not appreciably react. The net result on sorption of common and risk relevant mobile radionuclides is not expected to be significant. Specifically, little change in Cs-Kd values and a significant increase in Sr-Kd values were measured in the simulated glass leachates versus natural groundwater. The difference in the sorptive responses of the radionuclides was attributed to differences in sorption mechanisms (Cs sorbs strongly to high-energy sites, whereas Sr sorbs primarily by cation exchange but also is sensitive to pH mediated precipitation reactions). Caustic treated sediments contacted with NaOH solutions radiotraced with Sr exhibited high Kd’s likely because of precipitation with CaCO3. In caustic solutions there was no appreciable adsorption for the three anions I-, SeO42-, or TcO4-. In the “far field” vadose zone in past performance projections, some sorption has been allowed for selenate. Even if the caustic glass leachate completely dominates the entire vadose zone below the repository, such that there will be no sorption of selenate, the dilution and pH neutralization that will occur in the upper unconfined aquifer will allow selenate adsorption to occur onto the aquifer sediments. It is recommended that a future performance assessment sensitivity run be performed to address this point.

  7. Hydraulic redistribution in dwarf Rhizophora mangle trees driven by interstitial soil water salinity gradients: impacts on hydraulic architecture and gas exchange.

    PubMed

    Hao, Guang-You; Jones, Tim J; Luton, Corene; Zhang, Yong-Jiang; Manzane, Eric; Scholz, Fabian G; Bucci, Sandra J; Cao, Kun-Fang; Goldstein, Guillermo

    2009-05-01

    Rhizophora mangle L. trees of Biscayne National Park (Florida, USA) have two distinct growth forms: tall trees (5-10 m) growing along the coast and dwarf trees (1 m or less) growing in the adjacent inland zone. Sharp decreases in salinity and thus increases in soil water potential from surface soil to about a depth of 1 m were found at the dwarf mangrove site but not at the tall mangrove site. Consistent with our prediction, hydraulic redistribution detected by reverse sap flow in shallow prop roots was observed during nighttime, early morning and late afternoon in dwarf trees, but not in tall trees. In addition, hydraulic redistribution was observed throughout the 24-h period during a low temperature spell. Dwarf trees had significantly lower sapwood-specific hydraulic conductivity, smaller stem vessel diameter, lower leaf area to sapwood area ratio (LA/SA), smaller leaf size and higher leaf mass per area. Leaves of dwarf trees had lower CO(2) assimilation rate and lower stomatal conductance compared to tall trees. Leaf water potentials at midday were more negative in tall trees that are consistent with their substantially higher stomatal conductance and LA/SA. The substantially lower water transport efficiency and the more conservative water use of dwarf trees may be due to a combination of factors such as high salinity in the surface soil, particularly during dry periods, and substantial reverse sap flow in shallow roots that make upper soil layers with high salinity a competing sink of water to the transpiring leaves. There may also be a benefit for the dwarf trees in having hydraulic redistribution because the reverse flow and the release of water to upper soil layers should lead to dilution of the high salinity in the rhizosphere and thus relieve its potential harm to dwarf R. mangle trees. PMID:19324702

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

    Microsoft Academic Search

    Francisco J. Arriaga; Birl Lowery

    2003-01-01

    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

  9. Use of hydraulic fracturing to enhance soil vapor extraction - a case study

    SciTech Connect

    Baker, J.E.; Wells, S.L. [Golder Applied Technologies, Atlanta, GA (United States)

    1995-12-31

    Many environmental remediation activities can be cost effectively implemented through the use of soil vapor extraction. While this approach has been shown to work well in relatively high permeability soils, it is much less effective in low permeability silts and clays. The low permeability nature of these soils makes the flow of air required to remove volatile organic vapors difficult, if not impossible. Hydraulic soil fracturing, a modification of petroleum engineering technology to the environmental field, is a viable technique for overcoming this difficulty. The process involves injecting, under pressure, a high viscosity fluid which serves as the carrier for a sand propant. Enzymes which are mixed with the fluid cause the fracturing fluid to revert to a low permeability, allowing it to be pumped out, leaving a series of high permeability sand lenses. Several such lenses are injected at the site of each well, allowing efficient injection and/or extraction of vapors from the soil mass. The details of the fracture design and the results of the remedial action are presented.

  10. Tillage Effects on Soil Properties & Respiration

    NASA Astrophysics Data System (ADS)

    Rusu, Teodor; Bogdan, Ileana; Moraru, Paula; Pop, Adrian; Duda, Bogdan; Cacovean, Horea; Coste, Camelia

    2015-04-01

    Soil tillage systems can be able to influence soil compaction, water dynamics, soil temperature and soil structural condition. These processes can be expressed as changes of soil microbiological activity, soil respiration and sustainability of agriculture. Objectives of this study were: 1) to assess the effects of tillage systems (Conventional System-CS, Minimum Tillage-MT, No-Tillage-NT) on soil compaction, soil temperature, soil moisture and soil respiration and 2) to establish the relationship that exists in changing soil properties. Three treatments were installed: CS-plough + disc; MT-paraplow + rotary grape; NT-direct sowing. The study was conducted on an Argic-Stagnic Faeoziom. The MT and NT applications reduce or completely eliminate the soil mobilization, due to this, soil is compacted in the first year of application. The degree of compaction is directly related to soil type and its state of degradation. The state of soil compaction diminished over time, tending toward a specific type of soil density. Soil moisture was higher in NT and MT at the time of sowing and in the early stages of vegetation and differences diminished over time. Moisture determinations showed statistically significant differences. The MT and NT applications reduced the thermal amplitude in the first 15 cm of soil depth and increased the soil temperature by 0.5-2.20C. The determinations confirm the effect of soil tillage system on soil respiration; the daily average was lower at NT (315-1914 mmoli m-2s-1) and followed by MT (318-2395 mmoli m-2s-1) and is higher in the CS (321-2480 mmol m-2s-1). Comparing with CS, all the two conservation tillage measures decreased soil respiration, with the best effects of no-tillage. An exceeding amount of CO2 produced in the soil and released into the atmosphere, resulting from aerobic processes of mineralization of organic matter (excessive loosening) is considered to be not only a way of increasing the CO2 in the atmosphere, but also a loss of long-term soil fertility. Acknowledgments This paper was performed under the frame of the Partnership in priority domains - PNII, developed with the support of MEN-UEFISCDI, project no. PN-II-PT-PCCA-2013-4-0015: Expert System for Risk Monitoring in Agriculture and Adaptation of Conservative Agricultural Technologies to Climate Change.

  11. Field-Obtained Soil Water Characteristic Curves and Hydraulic Conductivity Functions

    NASA Astrophysics Data System (ADS)

    Elvis, Ishimwe

    A compacted clay liner (test pad) was constructed and instrumented with volumetric water content and soil matric potential sensors to determine soil water characteristic curves (SWCC) and hydraulic conductivity (k) functions. Specifically, the compacted clay liner was subjected to an infiltration cycle during a sealed double ring infiltrometer (SDRI) test followed by a drying cycle. After the drying cycle, Shelby tube samples were collected from the compacted clay liner and flexible wall permeability (FWP) tests were conducted on sub-samples to determine the saturated hydraulic conductivity. Moreover, two computer programs (RETC and UNSAT-H) were utilized to model the SWCCs and k-functions of the soil based on obtained measurements including the volumetric water content, the soil matric potential, and the saturated hudraulic conductivity (ks). Results obtained from the RETC program (s, r, ?, n and ks) were ingested into UNSAT-H program to calculate the movement of water (rate and location) through the compacted clay liner. Although a linear wetting front (location of water infiltration as a function of time) is typically utilized for SDRI calculations, the use of a hyperbolic wetting front is recommended as a hyperbolic wetting front was modeled from the testing results. The suggested shape of the wetting front is associated with utilization of the desorption SWCC instead of the sorption SWCC and with relatively high values of ks (average value of 7.2E-7 cm/sec) were measured in the FWP tests while relatively low values of ks (average value of 1.2E-7 cm/sec) were measured in the SDRI test.

  12. Mechanics and hydraulics of unsaturated soils: what makes interfaces an indispensable part of a physically-based model

    NASA Astrophysics Data System (ADS)

    Nikooee, E.; Hassanizadeh, S. M.

    2014-12-01

    The foundations of the current theories for hydraulics and mechanics of unsaturated soils have been mainly based on the empirically introduced equations. There are various characteristics of unsaturated soils for which lots of different empirical equations have been proposed such as hydraulic conductivity, water retention curve, and effective stress parameter. One of the remarkable challenges which all current models face is hysteresis, i.e., for a certain matric suction, values of saturation, hydraulic conductivity and effective stress parameter in drying state and wetting are different. Conventional models of hydraulic and mechanical behaviour of unsaturated soils try to account for the hysteresis phenomenon by means of different empirical equations for each hydraulic path. Hassanizadeh and Gray (1993) claimed that the hysteresis in capillary pressure-saturation curves can be modelled through the inclusion of air-water interfaces as a new independent variable [1]. It has recently been stated that the same conjecture can be made for suction stress [2]. Therefore, it seems to better portray hydraulic and mechanical behaviour of unsaturated soils, interfaces are required as an indispensable part of the framework [3, 4]. This presentation aims at introducing the drawbacks of current theories of hydraulics and mechanics of unsaturated soils. For this purpose, the role of interfaces in the mechanics and hydraulics of unsaturated soils is explained and different possibilities to account for the contribution of interfaces are discussed. Finally, current challenges and future research directions are set forth. References[1] Hassanizadeh, S.M. & Gray, W.G.: Thermodynamic basis of capillary pressure in porous media. Water Resour.Res. 29(1993), 3389-3405.[2] Nikooee, E., Habibagahi, G., Hassanizadeh, S.M. & Ghahramani, A.: Effective Stress in unsaturated Soils: a thermodynamic approach based on the interfacial energy and hydromechanical coupling. Transport porous Med. 96(2) (2013), 369-396.[3] Likos, W. J. Effective stress in unsaturated soil: Accounting for surface tension and interfacial area. Vadose Zone Journal, 13(5) (2014). [4] Joekar-Niasar, V. & Hassanizadeh, S. M.: Specific interfacial area: The missing state variable in two-phase flow equations? Water Resources Research 47(5) (2011).

  13. High-quality unsaturated zone hydraulic property data for hydrologic applications

    USGS Publications Warehouse

    Perkins, K.; Nimmo, J.

    2009-01-01

    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.

  14. Non-invasive 3D analysis of local soil deformation under mechanical and hydraulic stresses by ?CT and digital image correlation

    Microsoft Academic Search

    S. Peth; J. Nellesen; G. Fischer; R. Horn

    2010-01-01

    Soil deformation is a perpetual process in the pedosphere where besides physicochemical stresses primarily alternating hydraulic and mechanical stresses continuously re-arrange the configuration of solid particles. In this study we present a local strain analysis and changes in soil structure resulting from hydraulic and mechanical stresses based on X-ray microtomography data. Digital image reconstructions were used to quantify local structural

  15. Strategy to document heterogeneity in soil properties and its impact on water transfers from slope to catchment scales

    NASA Astrophysics Data System (ADS)

    Cohard, J.; Robert, D.; Descloitres, M.; Vandervaere, J.; Braud, I.; Vauclin, M.

    2011-12-01

    Heterogeneity in soil properties has been identified to impact water transfers at different scales from vertical column, hillslopes to watershed. Thus Distributed physically based hydrological models require distributed hydraulic characteristics to quantify these impacts. To characterize soil properties and their heterogeneity, a multi-scale sampling strategy was proposed based on distributed information including electromagnetic survey maps, topography and land use coverage. Each identified units are characterized by there hydraulic properties including in situ infiltration tests. This strategy was applied over the Ara Catchment (12km2) in northern Benin. It has been instrumented in the framework of the AMMA-Catch experimental network in West Africa, to better determine water resources and to investigate possible hydrological retro-action on monsoon cycle. From hydrological point of view, distributed soil hydraulic properties are supposed to impact water transfers and watershed dynamics all along the monsoon cycle. To document this heterogeneity, an electrical conductivity map and geological survey was used as starting points to identify the ground structures which align with the north-south direction with a dip angle of 20° east. A total of 20 pits have been opened to document the 0-2m horizons, and 2 more for the 0-5m horizons. 3 pits were digged within each geological structure areas at the surface. In each pit, the retention and hydraulic conductivity curves of each pedological horizon were characterized with three replicates. This database is used to document the variability of these properties and to produce soil hydraulic property maps. Using the variability information, we tested their impact with the Parflow-CLM 3D distributed model. It was run in an homogeneous configuration and compared with a data controlled heterogeneous configuration. The latest is prepared using a turning band algorithm to distribute soil hydraulic properties.

  16. 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...

  17. Investigating thickness and physical properties of forest soil along headwater hillslopes by hole drilling method

    NASA Astrophysics Data System (ADS)

    Han, Xiaole; Liu, Jintao

    2015-04-01

    Mountain torrents along headwater hillslopes usually occur during heavy rainfall and bring damage to people's lives and properties. Thus, the mechanism for flood generation process in mountain areas must be well studied. Soil acts as an important factor controlling this process. However, systematic studies the spatial distribution of soil properties, including soil thickness, bulky density, texture and infiltration rate along headwater hillslopes are rarely obtained. Therefore, the objective of this study is to explore the variation trend of these soil properties in a 3-D perspective. To do this, a total of 39 probe measurements were made by using a 70-mm-diameter gasoline vibrating drill in a small catchment (0.42 hectare). Measurements were made by push the gasoline drill into the soil until the bedrock was encounted. Then, the drill was pushed out from the soil and the undisturbed soil was obtained. The main results of the experiment show that: (a) soil thickness decreased significantly from the valley to the ridge (e.g., the maximum soil thickness in the valley and ridge are 164cm and 81 cm, respectively). (b)Vertically, taking borehole #1 as an example (148cm deep), the saturated hydraulic conductivity decreased significantly from 1.5 mm/min (0cm deep) to 0.01 mm/min (140cm deep). Spatially, the saturated hydraulic conductivity at same depth increased with the elevation increasing. (c) Particle size analysis indicated that the soil clay content increased with increasing sampling depth. To conclude, our study reveals the spatial distribution of soil properties which can help us to explore flowpaths and store in three-dimensional at hillslope scale and develop a parsimonious 3-D physics-based model to simulate hillslope hydrological response.

  18. Hydraulic and nutritional feedback controls surface patchiness of biological soil crusts at a post-mining site.

    NASA Astrophysics Data System (ADS)

    Fischer, Thomas; Gypser, Stella; Subbotina, Maria; Veste, Maik

    2015-04-01

    In a recultivation area located in Brandenburg, Germany, five types of biocrusts (initial BSC1, developed BSC2 and BSC3, mosses, lichens) and non-crusted mineral substrate were sampled on tertiary sand deposited in 1985-1986 to investigate hydrologic properties of crust patches. It was the aim of the study to demonstrate that (I) two types of BSC with alternative nutritional and hydraulic feedback modes co-exist in one area and that (II) these feedback modes are synergic. The sites to sample were selected by expertise, trying to represent mixed sites dominated by mosses, by lichens, and by visually in the field observable surface properties (colour and crust thickness) for the non-crusted substrate and BSC1 to 3. The non-crusted samples contained minor incrustations of the lichen Placynthiella oligotropha, young leaflets of the moss Ceratodon purpureus, as well as very sparsely present individuals of the green algae Ulothrix spec., Zygogonium spec. and Haematococcus spec. The sample BSC1 was not entirely covered with microphytes, crust patches were smooth, and P. oligotropha was observed to develop on residues of C. purpureus and on unspecified organic detritus. BSC2 covered the surface entirely and was dominated by P. oligotropha and by Zygogonium spec. The sample BSC3 consisted of pad-like patches predominantly growing on organic residues. The moss sample was dominated by C. purpureus and Zygogonium spec. growing between the moss stemlets directly on the mineral surface, the lichen sample was dominated by Cladonia subulata with sparsely scattered individuals of C. purpureus. Hierarchical cluster analysis revealed that BSC2 was floristically and chemically most similar to the moss crust, whereas BSC3 was floristically and chemically most similar to the lichen crust. Crust biomass was lowest in the non-crusted substrate, increased to the initial BSC1 and peaked in the developed BSC2, BSC3, the lichens and the mosses. Water infiltration was highest on the substrate, and decreased to BSC2, BSC1 and BSC3. Non-metric multidimensional scaling revealed that the lichens and BSC3 were associated with water soluble nutrients (NO3, NH4, K, Mg, Ca) and with pyrite weathering products (pH, SO4), thus representing a high nutrient low hydraulic feedback mode. The mosses and BSC2 represented a low nutrient high hydraulic feedback mode. These feedback mechanisms were considered as synergic, consisting of run-off generating (low hydraulic) and run-on receiving (high hydraulic) BSC patches. Three scenarios for BSC succession were proposed. (1) Initial BSCs sealed the surface until they reached a successional stage (represented by BSC1) from which the development into either of the feedback modes was triggered, (2) initial heterogeneities of the mineral substrate controlled the development of the feedback mode, and (3) complex interactions between lichens and mosses occurred at later stages of system development. It was concluded that, irrespective of successional pathways, two synergic feedback mechanisms contributed to the generation of self-organized surface patchiness. Such small-scale microsite differentiation with different BSCs has important implications for the vegetation in post-mining sites. Reference Fischer, T., Gypser, S., Subbotina, M., Veste, M. (2014) Synergic hydraulic and nutritional feedback mechanisms control surface patchiness of biological soil crusts on tertiary sands at a post-mining site. Journal of Hydrology and Hydromechanics 62(4):293-302

  19. Impact of soil properties on selected pharmaceuticals adsorption in soils

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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).

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

    Microsoft Academic Search

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

    1995-01-01

    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

  1. Hydraulic properties of three types of glacial deposits in Ohio

    USGS Publications Warehouse

    Strobel, M.L.

    1993-01-01

    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.

  2. [Hydraulic limitation on photosynthetic rate of old Populus simonii trees in sandy soil of north Shaanxi Province].

    PubMed

    Zuo, Li-Xiang; Li, Yang-Yang; Chen, Jia-Cun

    2014-06-01

    'Old and dwarf trees' on the loess plateau region mainly occurred among mature trees rather than among small trees. To elucidate the mechanism of tree age on 'old and dwarf trees' formation, taking Populus simonii, a tree species that accounted for the largest portion of 'old and dwarf trees' on the loess plateau, as an example, the growth, photosynthesis and hydraulic traits of P. simonii trees with different ages (young: 13-15 years, mid-aged: 31-34 years, and old: 49-54 years) were measured. The results showed that the dieback length increased, and net photosynthetic rate, stomatal conductance, transpiration rate, and whole plant hydraulic conductance decreased significantly with the increasing tree age. Both net photosynthetic rate and stomatal conductance measured at different dates were significantly and positively related to the whole plant hydraulic conductance, suggesting that the decreasing photosynthetic rate of old trees was possibly caused by the declined hydraulic conductance. Although the resistance to cavitation in stems and leaves was stronger in old trees than in young and mid-aged trees, there were no differences in midday native stem embolization degree and leaf hydraulic conductance based on the vulnerability curve estimation, suggesting that the increased hydraulic resistance of the soil-root system is probably the most important reason for decreasing the whole plant hydraulic conductance of old trees. PMID:25223014

  3. Application of the Ferris test methods for estimating hydraulic properties near a river boundary

    SciTech Connect

    Gilmore, T.J.; Spane, F.A. Jr.

    1993-10-01

    Standard hydraulic test methods, such as constant-rate pumping tests, may be impractical for characterizing hazardous waste sites located near fluctuating hydrologic boundaries such as rivers or oceans. An alternate approach for hydrologic characterization at these locations is to analyze the groundwater responses associated with river-stage or tidal fluctuations to aquifer properties (i.e., hydraulic diffusivity). Based on this approach, aquifer properties were determined for an area adjoining the Columbia River on the Hanford Site using two sinusoidal analysis techniques described in Ferris (1952, 1963). The first method uses the observed groundwater time-lag response, the second uses the amplitude ratio of well water level to river stage. Both techniques assume the river fluctuations can be approximated by a sinusoidal pattern. A range for hydraulic conductivity was calculated based on the hydraulic diffusivity estimates obtained from the methods together with the known aquifer thickness (50 ft) and assumed specific yield (0.1). The analysis methods produced two overlapping hydraulic conductivity ranges, with the Ferris time-lag analysis method forming the upper bound of the range, and the Ferris well water-level/river-stage amplitude ratio method forming the lower bound. Results from a nearby standard constant-rate discharge aquifer test were also examined for comparison. These results were within the upper bound of the hydraulic conductivity range.

  4. Space agriculture: the effect of micro- and hypogravity on soil hydraulics and biogeochemistry in a bioregenerative soil-based cropping unit

    Microsoft Academic Search

    F. Maggi; C. E. Pallud

    2010-01-01

    Abstract Increasing interest has developed towards growing plants in soil-based cropping modules as a long-term bioregenerative life support system in space and planetary explorations. Contrary to hydroponics, zeoponics 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 for the crew. The hydraulic and biogeochemical functioning

  5. Thermal properties of soils and soils testing. Final report

    Microsoft Academic Search

    M. J. Waller; T. P. Bligh

    1983-01-01

    Thermal conductivity of dry moist soils and the difficulty of measuring thermal properties are discussed. The MIT thermal conductivity probe is presented along with a description of the design issues, validation experiments, errors, manufacturing and experimental procedures for using the probes in the laboratory and field (for continuous data gathering or for single or multiple measurements). A new method for

  6. Passive characterization of hydrofracture properties using signals from hydraulic pumps

    SciTech Connect

    Rector III, J.W.; Dong, Q.; Patzek, T.W.

    1999-01-02

    Massive hydraulic fracturing is used to enhance production from the low-permeability diatomite fields of Kern County, CA. Although critical for designing injection and recovery well patterns, the in-situ hydraulic fracture geometry is poorly understood. In 1990, Shell conducted an extensive seismic monitoring experiment on several hydrofractures prior to a steam drive pilot to characterize hydrofracture geometry. The seismic data were recorded by cemented downhole geophone arrays in three observation holes (MO-1, MO-2, and MO-3) located near the hydraulic fracture treatment wells. Using lowpass filtering and moveout analysis, events in the geophone recordings are identified as conical shear waves radiating from tube waves traveling down the treatment well. These events appear to be created by the hydraulic pumps, since their amplitudes are correlated with the injection rate and the wellhead pressure. Conical wave amplitudes are related to the tube wave attenuation in the treatment well and to wave-propagation characteristics of the shear component traveling in the earth. During the main fracturing stage, geophones above the fracture zone for wells MO-1 and MO-2 (both roughly along the inferred vertical fracture plane) exhibited conical-wave amplitude increases that are caused by shear wave reflection/scattering off the top of a fracture zone. From changes in the reflection amplitude as a function of depth, we interpret that the fracture zone initially extends along a confined vertical plane at a depth that correlates with many of the microseismic events. Toward the end of the main fracturing stage, the fracture zone extends upward and also extends in width, although we cannot determine the dimensions of the fracture from the reflection amplitudes alone. For all wells, we observe that the reflection (and what we infer to be the initial fracture) begins during a time period where no marked change in fracture pressure or injection rate or slurry concentration is observed. As the main fracturing stage progressed, we observed a significant decrease in amplitude for geophones below the top of the fracture zone. The attenuation was most pronounced for wells MO-1 and MO-2 (along the fracture plane). However, near the end of the main stage, well MO-3 also exhibited a significant amplitude decrease, suggesting the development of a fractured ''process zone'' around the main fracture plane. In addition, well MO-3 also exhibited an amplitude decrease in an interval well below the initial fracture zone. Both the interval and the direction (toward MO-3) correspond with temperature log increases observed during later steam injection.

  7. Effects of historic charcoal burning on soil properties

    NASA Astrophysics Data System (ADS)

    Hirsch, Florian; Schneider, Anna; Raab, Alexandra; Raab, Thomas; Buras, Allan; van der Maaten, Ernst; Takla, Melanie; Räbiger, Christin; Cruz Garcia, Roberto; Wilmking, Martin

    2015-04-01

    In Northeastern Germany the production of ironware between the 16th and 19th century left behind a remarkable amount of charcoal kiln remains. At the study site in the forests north of Cottbus, Rubic Brunic Arenosols are developed on Weichselian glaciofluvial deposits. Remote sensing surveys, underpinned by archaeological studies, show that charcoal was gained from several thousand kilns. The round charcoal kiln remains with inner diameters up to 20 m are smooth platforms elevated a few decimeters higher than the surrounding area. The remaining mounds consist of an about 40 cm thick sheet containing residuals of the charcoal production process such as charcoal fragments, ash but also organic material covering the Rubic Brunic Arenosols. The charcoal kiln remains are distanced only up to 100 m from each other. For the 32 square kilometers large study site, the ground area covered by such charcoal production residuals is about 0.5 square kilometer, i.e. 1.5% of the study area. The charcoal kiln sites are a remarkable carbon accumulator on the sandy parent material. Against this background, we aim to characterize the effects of pyrolysis and the enrichment of carbon, induced by the charcoal production, on soil properties. Field work was done during archaeological rescue excavations on three charcoal kiln relicts having diameters of about 15 m. We applied 150 l of Brilliant Blue solution on six 1 square meter plots (three inside, three outside of the charcoal kiln mound) and afterwards trenched horizontal and vertical profiles for recording the staining patterns. Undisturbed soil samples to study soil micromorphology and further undisturbed samples for characterizing soil physical and hydraulic properties were taken. Outside of the charcoal kiln remain the Brilliant Blue solution drained within less than 10 minutes, whereas on the charcoal kiln remains the draining took between 20 and 40 minutes. Preliminary laboratory analyses underline the findings from the field and indicate that the carbon rich kiln residuals have a higher field capacity than the surrounding Arenosols. The matrix potential of the carbon rich kiln substrate is high and water drop penetration time tests show high water repellency. Our findings suggest that although the charcoal production led to an enrichment of carbon in the landscape, the hydraulic properties of the remaining ash layers can have negative effects on the water supply for plants.

  8. Contrasting effects of soil development on hydrological properties and flow paths

    NASA Astrophysics Data System (ADS)

    Lohse, Kathleen A.; Dietrich, William E.

    2005-12-01

    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 old Oxisol, located at the extreme ends of a soil substrate age gradient across the Hawaiian Islands. The two soils contrasted in depth and texture; the young soil was shallow and coarse textured, while the old soil was deep and highly weathered with a near-surface plinthite horizon overlying numerous clay-rich subsurface horizons. The young soil drained freely under modest suction, whereas subsurface clay horizons at the old site required significantly more suction to start to drain than the upper horizons. Similarly, saturated hydraulic conductivity (Ks) was high throughout the soil profile at the young site, whereas Ks was two to three orders of magnitude lower through the subsurface clay horizons than the upper ones at the old site. Irrigation experiments with deuterium tracer demonstrated that water was downward advecting at the young site, while water at the old site moved both laterally along the subsurface clay horizon contact and slowly downward through it. Rainfall frequency distributions indicated a high probability of rainfall events exceeding subsurface Ks values in old soil. In Hawaii the addition of dust influences the time evolution of soil, but the tendency for subsoil clay accumulation in older soils leading to alteration in hydrologic flow paths has been proposed in other environments. Our findings together suggest that as soils develop with time, subsurface horizon Ks values decline, impeding rates of vertical water flow but also increasing the importance of shallow subsurface lateral flow.

  9. Minimum property dataset and sampling requirement tool for soil change studies in soil survey

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dynamic soil properties (DSP) are those properties that change over human time scales. The new sampling guide “Soil and Resource Inventory Guide for Dynamic Soil Properties and Soil Change” includes a minimum DSP dataset and an interactive tool to determine sampling requirements. The minimum dataset...

  10. Relationships between induced polarization relaxation time and hydraulic properties of sandstone

    Microsoft Academic Search

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

    2010-01-01

    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

  11. Non-hydraulic signals from maize roots in drying soil: inhibition of leaf elongation but not stomatal conductance.

    PubMed

    Saab, I N; Sharp, R E

    1989-11-01

    Conditions of soil drying and plant growth that lead to non-hydraulic inhibition of leaf elongation and stomatal conductance in maize (Zea mays L.) were investigated using plants grown with their root systems divided between two containers. The soil in one container was allowed to dry while the other container was kept well-watered. Soil drying resulted in a maximum 35% inhibition of leaf elongation rate which occurred during the light hours, with no measurable decline in leaf water potential (?w). Leaf area was 15% less than in control plants after 18 d of soil drying. The inhibition of elongation was observed only when the soil ?w declined to below that of the leaves and, thus, the drying soil no longer contributed to transpiration. However, midday root ?w in the dry container (-0.29 MPa) remained much higher than that of the surrounding soil (-1.0 MPa) after 15 d of drying, indicating that the roots in drying soil were rehydrated in the dark.To prove that the inhibition of leaf elongation was not caused by undetectable changes in leaf water status as a result of loss of half the watergathering capacity, one-half of the root system of control plants was excised. This treatment had no effect on leaf elongation or stomatal conductance. The inhibition of leaf elongation was also not explained by reductions in nutrient supply.Soil drying had no effect on stomatal conductance despite variations in the rate or extent of soild drying, light, humidity or nutrition. The results indicate that non-hydraulic inhibition of leaf elongation may act to conserve water as the soil dries before the occurrence of shoot water deficits. PMID:24201770

  12. Influence of Robinia pseudoacacia short rotation coppice on soil physical properties

    NASA Astrophysics Data System (ADS)

    Xavier, Morvan; Isabelle, Bertrand; Gwenaelle, Gibaud

    2015-04-01

    Human activities can lead to the degradation of soil physical properties. For instance, machinery traffic across the land can induce the development of compacted areas at the wheel tracks. It leads to a decrease in porosity which results in a decrease of the hydraulic conductivity, and therefore, prevents water infiltration and promotes surface runoff. Land use, soil management and soil cover also have a significant influence on soil physical properties (Kodesova et al., 2011). In the arable land, surface runoff and soil erosion are enhanced by the absence of soil cover for part of the year and by the decrease of aggregate stability due to a decline of soil organic matter. In that context, few studies focused on the effects of a Robinia pseudoacacia short rotation coppice (SRC) on soil physical properties. Therefore, this study aims to determine the effect of the conversion of a grassland in a SRC on soil physical properties. These properties have also been compared to those of arable land and natural forest. For that, in several plots of the experimental farm of Grignon (30 km west of Paris, France), different measurements were performed: i) soil water retention on a pressure plate apparatus for 7 water potential between 0 and 1500 kPa, ii) bulk density using the method for gravelly and rocky soil recommended by the USDA, iii) aggregate stability using the method described in Le Bissonnais (1996), and iv) soil hydraulic conductivity using a Guelph permeameter. All these measurements were performed on the same soil type and on different land uses: arable land (AL), grassland (GL), natural forest (NF) and short rotation coppice (SRC) of Robinia pseudoacacia planted 5 years ago. Soil water retention measurements are still under progress and will be presented in congress. Bulk density measurements of the AL, GL and SRC are not significantly different. They ranged from 1.32 to 1.42. Only the NF measurements are significantly lower than the other (0.97). Aggregate stability measurements showed that the SRC soil had the most stable aggregates compared to the other land uses. SRC also had the highest infiltration rates (656 mm.h-1) compared to NF (54 mm.h-1), GL (23 mm.h-1) and AL (8 mm.h-1). Analyses and explanation of these results are still under progress and will be presented in congress. Kodesova, R., Jirku, V., Kodes, V., Muhlhanselova, M., Nikodem, A., Žigová, A., 2011. Soil structure and soil hydraulic properties of Haplic Luvisol used as arable land and grassland. Soil and Tillage Research 111 (2), pp. 154-161. Le Bissonnais Y., 1996. Aggregate stability and assessment of soil crustability and erodibility: I theory and methodology. European Journal of Soil Science 47, 425-437.

  13. Setting properties and sealing ability of hydraulic temporary sealing materials.

    PubMed

    Ogura, Yoko; Katsuumi, Ichiroh

    2008-09-01

    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

  14. Quasi-steady centrifuge method for unsaturated hydraulic properties

    USGS Publications Warehouse

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

    2005-01-01

    [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.

  15. 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...

  16. Near Surface Electrical Characterization of Hydraulic Conductivity: From Petrophysical Properties to Aquifer Geometries—A Review

    Microsoft Academic Search

    Lee Slater

    2007-01-01

    This paper reviews the recent geophysical literature addressing the estimation of saturated hydraulic conductivity (K) from static low frequency electrical measurements (electrical resistivity, induced polarization (IP) and spectral induced\\u000a polarization (SIP)). In the first part of this paper, research describing how petrophysical relations between electrical properties\\u000a and effective (i.e. controlling fluid transport) properties of (a) the interconnected pore volumes and

  17. Innovative Field Methods for Characterizing the Hydraulic Properties of a Complex Fractured Rock Aquifer (Ploemeur, Brittany)

    NASA Astrophysics Data System (ADS)

    Bour, O.; Le Borgne, T.; Longuevergne, L.; Lavenant, N.; Jimenez-Martinez, J.; De Dreuzy, J. R.; Schuite, J.; Boudin, F.; Labasque, T.; Aquilina, L.

    2014-12-01

    Characterizing the hydraulic properties of heterogeneous and complex aquifers often requires field scale investigations at multiple space and time scales to better constrain hydraulic property estimates. Here, we present and discuss results from the site of Ploemeur (Brittany, France) where complementary hydrological and geophysical approaches have been combined to characterize the hydrogeological functioning of this highly fractured crystalline rock aquifer. In particular, we show how cross-borehole flowmeter tests, pumping tests and frequency domain analysis of groundwater levels allow quantifying the hydraulic properties of the aquifer at different scales. In complement, we used groundwater temperature as an excellent tracer for characterizing groundwater flow. At the site scale, measurements of ground surface deformation through long-base tiltmeters provide robust estimates of aquifer storage and allow identifying the active structures where groundwater pressure changes occur, including those acting during recharge process. Finally, a numerical model of the site that combines hydraulic data and groundwater ages confirms the geometry of this complex aquifer and the consistency of the different datasets. The Ploemeur site, which has been used for water supply at a rate of about 106 m3 per year since 1991, belongs to the French network of hydrogeological sites H+ and is currently used for monitoring groundwater changes and testing innovative field methods.

  18. 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...

  19. The effect of hydraulic lift on organic matter decomposition, soil nitrogen cycling, and nitrogen acquisition by a grass species

    Microsoft Academic Search

    Cristina ArmasJohn; John H. Kim; Timothy M. Bleby; Robert B. Jackson

    Hydraulic lift (HL) is the passive movement of water through plant roots, driven by gradients in water potential. The greater\\u000a soil–water availability resulting from HL may in principle lead to higher plant nutrient uptake, but the evidence for this\\u000a hypothesis is not universally supported by current experiments. We grew a grass species common in North America in two-layer\\u000a pots with

  20. Radial Hydraulic Conductivity of Individual Root Tissues of Opuntia ficus-indica(L.) Miller as Soil Moisture Varies

    Microsoft Academic Search

    GRETCHEN B. NORTH; PARK S. NOBEL

    1996-01-01

    The constraints on water uptake imposed by individual root tissues were examined forOpuntia ficus-indicaunder wet, drying, and rewetted soil conditions. Root hydraulic conductivity (LP) and axial conductance (Kh) were measured for intact root segments from the distal region with an endodermis and from midroot with a periderm;LPwas then measured for each segment with successive tissues removed by dissection. Radial conductivity

  1. A Hydraulic (flow) Unit based model for the determination of petrophysical properties from NMR relaxation measurements

    SciTech Connect

    Ohen, H.A. [SPE, Richardson, TX (United States); Ajufo, A.; Curby, F.M. [Core Laboratories, Houston, TX (United States)

    1995-12-31

    This paper presents preliminary results of a Hydraulic (flow) Units based research program aimed at defining more effective guidelines for the use of nuclear magnetic resonance tools (NMRT) for petrophysical evaluation. Successful application of the Hydraulic Units concept for predicting petrophysical properties from wireline logs has been demonstrated previously. In this paper, we show obvious but crucial relationships between the Hydraulic Units concept and nuclear magnetic resonance (NMR) relaxation data. The linkage between these two technologies is possible because the hydraulic unit zonation indicators referred to as flow zone indicators (FZI) and NMR relaxation data are related to the surface phenomenon which controls the microscopic attributes of the rock. It is shown that although NMR relaxation measurements respond to pore body size rather than pore throat size, an effective NMR based permeability model, which includes pore size to pore throat size ratios, can be developed. The phenomenological model presented herein consists of mathematical relationships between FZI and NMR relaxation data, specific surface area, tortuosity and relaxivity ({rho}). Laboratory (NMR) relaxation time measurements on CORESPEC-1000 together with core analysis data of permeability, porosity, centrifuge capillary pressure and thin section petrography have been used to validate the model. The results show that the observed variability in the relaxivity constant ({rho}) is due to the existence of different hydraulic units in the reservoir rock. We also demonstrate that relaxation time cut-off (T{sub 1c}) used for determining producible fluid from relaxation time distributions may vary slightly as a function of rock types. Hydraulic units based predictive algorithms for the estimation of relaxivity ({rho}) and T{sub 1c}, using pore throat size distributions (mercury injection data), and centrifuge capillary pressure data are validated.

  2. Soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil is a diverse natural material characterized by solid, liquid, and gas phases that impart unique chemical, physical, and biological properties. Soil provides many key functions, including supporting plant growth and providing environmental remediation. Monitoring key soil properties and processe...

  3. Carbofuran biodegradation in brackish groundwater and its effect on the hydraulic properties of the porous medium

    NASA Astrophysics Data System (ADS)

    Amiaz, Yanai; Ronen, Zeev; Adar, Eilon; Weisbrod, Noam

    2015-04-01

    A chalk fractured aquitard beneath an industrial site is subjected to intense contamination due to percolation of contaminants from the different facilities operating at the site. In order to reduce further contamination, draining trenches were excavated and filled with coarse gravel (3-4 cm in diameter) forming a porous medium, to which the contaminated groundwater discharges from the fractures surrounding the trenches. This research is aimed at establishing a biodegrading process of high efficiency and performance within the draining trenches. The research includes both field and laboratory experiments. An experimental setup of five columns (50 cm length and 4.5 cm in diameter) was constructed under highly controlled conditions. Over the course of the experiments, the columns were filled with different particle sizes and placed in a temperature controlled chamber. Filtered groundwater (0.2 µm) from the site groundwater, enriched by a model contaminant carbofuran (CRF), was injected to the columns; as two of the columns were inoculated by CRF degrading microorganisms native in the site's groundwater, two columns were inoculated by CRF degrading bacteria from the external environment, and one column was used as a control. During the experiment, measurements were taken from different locations along each column. These include: (a) CRF concentration and (b) hydraulic pressure and solution viscosity (in order to obtain the changes in permeability). A tracer test using uranine was carried out in parallel, in order to obtain the changes in hydraulic parameters. Correlating CRF concentration variations to changes of hydraulic parameters enable the deduction due to the effect that biological activity (under different temperature regimes) has on the hydraulic properties of the porous medium and its effect on the process of contaminant groundwater bodies' remediation. Preliminary results suggest that although biodegradation occurs, microbial activity has minor effect on the hydraulic properties of the porous medium under the explored conditions.

  4. Soil properties affecting volatilization of ammonia from soils treated with urea

    Microsoft Academic Search

    D. A. Martens; J. M. Bremner

    1989-01-01

    The effects of various soil properties on ammonia (NH3) volatilization from soils treated with urea were studied by measuring the NH3 evolved when 20 soils selected to obtain a wide range in properties were incubated at ?0.034 mPa soil moisture potential and 30°C for 10 days after treatment with urea. The nitrogen (N) volatilized as NH3 from these soils represented

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

    Microsoft Academic Search

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

    2010-01-01

    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

  6. Modeling as a tool for management of saline soils and irrigation waters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Optimal management of saline soils and irrigation waters requires consideration of many interrelated factors including, climate, water applications and timing, water flow, plant water uptake, soil chemical reactions, plant response to salinity and solution composition, soil hydraulic properties and ...

  7. Effects of soil physical properties on GPR for landmine detection

    Microsoft Academic Search

    Timothy W. Miller; Brian Borchers; Jan M. H. Hendrickx; Sung-Ho Hong; Louis W. Dekker; Coen J. Ritsema

    2002-01-01

    Field experience has shown that soil conditions can have large effects on Ground Penetrating Radar (GPR) detection of landmines. We discuss available models for the prediction of the dielectric constant from soil physical properties including bulk density, soil texture, and water content. The soil dielectric constant determines the attenuation of the radar signal. The contrast between the dielectric constant of

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

    PubMed

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

    2015-03-01

    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

  9. Interactions of Soil Order and Land Use Management on Soil Properties in the Kukart Watershed, Kyrgyzstan

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Surveys of soil properties related to soil functioning for many regions of Kyrgyzstan are limited. This study established ranges of selected chemical [soil organic matter (SOM), pH and total N (TN)], physical (soil texture), and biochemical (six enzyme activities of C, N, P and S cycling) character...

  10. Nickel Adsorption Characteristics of Selected Soils as Related to Some Soil Properties

    Microsoft Academic Search

    E. Adhami; A. Salmanpour; A. Omidi; N. Khosravi; R. Ghasemi-Fasaei; M. Maftoun

    2008-01-01

    There is little information on Nickel (Ni) adsorption by calcareous soils of Iran. The pattern of Ni retention and its relationships with soil properties in soils from the southern part of Iran (SSI) and northern part of Iran (SNI) was studied. Amount of Ni adsorption was calculated after the equilibration of 1 g soil samples in duplicate with 25 mL

  11. Guidelines for sampling for dynamic soil properties for soil survey updates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dynamic soil property data can be collected during soil survey updates to add value to soil survey products and meet users’ needs. Producers and land managers need information about soil and ecosystem change in order to plan for long-term productivity, conduct monitoring and assessments and predict ...

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

    USGS Publications Warehouse

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

    1989-01-01

    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

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

    PubMed Central

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

    2013-01-01

    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 while water samples collected from the same locations were analyzed for Br?, Cl?, NO3?, SO42?, NH4+, Fe2+, and total sulfide. Compared to homogenous 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 1-2 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. Findings also provide justification for considering soil layering in contaminant fate and transport models because of its potential to increase biodegradation and/or slow the rate of transport of contaminants. PMID:22031578

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

    E-print Network

    Paris-Sud XI, Université de

    1 Running heading: Water retention properties of the clay in clayey soils Water retention properties of the clay in soils developed on clayey sediments: Significance of parent material and soil of clayey subsoils horizons according to the variation of clay characteristics. The horizons studied

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

    SciTech Connect

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

    2005-05-05

    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.

  16. In-situ Hydraulic Property Estimation With Minimum Chemical/Microbiological Disturbance for HC Modeling of Sedimentary Rocks

    NASA Astrophysics Data System (ADS)

    Ito, K.; Suzuki, Y.; Suko, T.; Seki, Y.; Takeno, N.

    2007-12-01

    For the investigations with drill holes aiming at a modeling of groundwater flow and mass transport with chemical and microbiological interactions, the minimization of chemical disturbance caused by drilling and in-situ hydraulic test is necessary for the long-term monitoring of groundwater chemistry and microbiological conditions. The authors carried out 350m drilling with ultra-filtered and deoxygenated drilling water in stable sedimentary rock area, and applied fluid electric conductivity (FEC) logging, flowmeter logging to estimate hydraulic properties along the borehole. For the continuous monitoring, the multi-packer type pressure measuring and sampling system was installed to monitor hydraulic pressure and chemical/microbiological environments. By using the transient pressure change at the water sampling as a small pressure pulse, hydraulic properties of sampling intervals were estimated with numerical inversion. Chemical analyses of groundwater samples showed the discontinuous profile split by tuff layer in massive mudstone. From the results of FEC logging, the authors calculated relative transmissivities and hydraulic heads of representative inflow/outflow points, and these values showed good accordance with flowmeter logging and multi-packer pressure measurements. With the hydraulic property and hydraulic head profile obtained in these measurements, groundwater flow model that gave a reasonable accounts to the chemical profile could be constructed.

  17. Measurement and Analysis of Physical and Hydraulic Properties of Unsaturated Peat Using 3D Micro CT Scanning

    Microsoft Academic Search

    F. Rezanezhad; W. Quinton; J. Price; D. Elrick; T. Elliot; K. Shook

    2009-01-01

    The hydraulic conductivity of unsaturated peat with a wetting phase is controlled by the peat structure which affects the air-filled porosity, pore size distribution and shape. This study investigates how the size and geometry of pores affects the flow of water through peat soil. To examine the effects of pore size and geometric characteristics of the air-filled pores on unsaturated

  18. Daily dynamics of leaf and soil-to-branch hydraulic conductance in silver birch (Betula pendula) measured in situ.

    PubMed

    Õunapuu, Eele; Sellin, Arne

    2013-07-01

    Daily dynamics of leaf (K(L)) and soil-to-branch hydraulic conductance (KS-B) was investigated in silver birch (Betula pendula Roth.) using evaporative flux method in situ: water potential drop was measured with a pressure chamber and evaporative flux was estimated as sap flux density measured with sap flow gauges. Canopy position had a significant (P < 0.001) effect on both K(L) and K(S-B). Upper-canopy leaves exhibited 1.7 and soil-to-branch pathway 2.3 times higher hydraulic efficiency than those for lower-canopy. K(L) varied significantly with time of day: K(L) for both upper- and lower-canopy leaves was lowest in the morning and rose gradually achieving maximal values in late afternoon (4.75 and 3.38 mmol m?² s?¹ MPa?¹, respectively). Relevant environmental factors affecting K(L) were photosynthetic photon flux density (Q(P)), air relative humidity (RH) and air temperature (T(A)). K(S-B) started rising in the morning and reached maximum in the lower canopy (1.44 mmol m?² s?¹ MPa?¹) at 1300 h and in the upper canopy (2.52 mmol m?² s?¹ MPa?¹) at 1500 h, decreasing afterwards. Environmental factors controlling K(S-B) were ?(S) and Q(P). The diurnal patterns of K(L) reflect a combination of environmental factors and endogenous rhythms. The temporal pattern of K(S-B) refers to daily up- and down-regulation of hydraulic conductance of water transport pathway from soil-root interface to leaves with respect to changing irradiance. PMID:23681117

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

    PubMed

    Saint-Fort, Roger; Ashtani, Sahar

    2014-01-01

    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

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

    NASA Technical Reports Server (NTRS)

    Carr, Stacy; Tsegaye, Teferi; Coleman, Tommy

    1998-01-01

    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.

  1. SSSAJ: Volume 75: Number 1 JanuaryFebruary 2011 17 Soil Sci. Soc. Am. J. 75:1725

    E-print Network

    Perfect, Ed

    -State Centrifugation SoilPhysics The capillary pressure­saturation function is an important hydraulic property recovery, subsurface C sequestration, and remediation of contaminated soils. In soil physics, the capillary

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

    Microsoft Academic Search

    J. H. Richards; M. M. Caldwell

    1987-01-01

    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

  3. Use of gravity and drawdown information to estimate hydraulic properties during unconfined aquifer testing

    NASA Astrophysics Data System (ADS)

    Blainey, J. B.; Ferre, T. P.

    2007-12-01

    High-resolution gravimetry measured at the ground surface may offer a cost-effective method to augment aquifer tests in unconfined aquifers without the expense of installing additional monitoring wells or piezometers. However, evaluating the usefulness of gravity, used either alone or together with piezometric measurements, to help constrain hydraulic parameters through aquifer testing is difficult because observations of drawdown in a monitoring well and gravity measurements respond to different physical states of the system at different spatial scales. Measurements of drawdown provide a direct measure of the energy potential local to the observation location, while measurements of gravity change indirectly measure changes in water storage and depend on the spatially-weighted average of the subsurface density change integrated over a large measurement volume. Hydrogeophysical numerical experiments are conducted to examine the value of drawdown and gravity responses for constraining aquifer test analyses based on synthetic measurements at nine ground-surface locations after seven days of pumping. We confirm that the conditions conducive to this use of gravity measurements are those that lead to a sufficiently large change in gravity signal: high drainable porosity of the aquifer, low depth to the water table, and small distance from the pumping well to a gravity measurement location. However, we further demonstrate that the ability of a gravimeter to detect a signal above the noise in the data is not a sufficient condition to guarantee utility of the measurement method to constrain hydraulic parameter estimation. Specifically, the inference of hydraulic properties requires consideration of parameter interaction and parameter sensitivity to instrument responses in addition to instrument resolution and signal detectability. For conditions amenable to gravity monitoring, combined use of drawdown and gravity data resulted in unbiased and precise estimates of both hydraulic conductivity and specific yield. This offers improvement over monitoring drawdown alone, which often provides poor estimates of specific yield.

  4. Pumping-Test Evaluation of Fault-Zone Hydraulic Properties in a Fractured Sandstone

    NASA Astrophysics Data System (ADS)

    Johnson, N. M.

    2014-12-01

    Subzones of both reduced and enhanced permeability are often ascribed to fault zones, consistent with a fault-core/damage-zone conceptualization, with associated implications for assessing potential contaminant transport. Within this context, a 31-day pumping test was conducted in relation to a relatively minor, 2000 m long fault zone cutting fractured Cretaceous sandstone interbedded with siltstone and shale at a groundwater remediation site in the Simi Hills of southern California during March-April 2013. Our objective was to evaluate the potential hydrogeologic influence of the fault zone on groundwater movement across and along it by observing the spatial patterns of drawdown and estimated hydraulic properties. A 122 m deep open borehole was pumped at a constant rate of approximately 112 L/min while monitoring hydraulic heads in 14 observation wells, two completed with multi-level systems, within 750 m of the pumping well. Hydraulic heads were monitored for more than 9 months before, during, and after the test. Prior to the test, we used the site's three-dimensional, equivalent-porous-media groundwater flow model to anticipate the potential response of alternative fault-zone permeability structures. The results suggest that the fault zone may be slightly more permeable (by a factor of about 2 or less) and less confined than the fractured sandstone away from the fault, and is not a significant barrier to groundwater flow across it. Within the areal extent of observed drawdown, the site's hydrostratigraphic structures exhibited a relatively greater hydraulic influence. The pattern and magnitude of observed drawdown lie within the range of pre-test model simulations, and the test results are now being used to revise and recalibrate the model.

  5. Soil property effects on wind erosion of organic soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Histosols (also known as organic soils, mucks, or peats) are soils that are dominated by organic matter (>20%) in half or more of the upper 80 cm. Forty four states have a total of 21 million ha of histosols in the United States. These soils, when intensively cropped, are subject to wind erosion r...

  6. Soil Property Effects on Wind Erosion of Organic Soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Histosols (also known as organic soils, mucks, or peats) are soils that are dominated by organic matter (>20%) in half or more of the upper 80 cm. Forty four states have a total of 21 million ha of histosols in the United States. These soils, when intensively cropped, are subject to wind erosion r...

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

    USGS Publications Warehouse

    Kay, Robert T.; Earle, John D.

    1990-01-01

    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.

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

    PubMed

    Kocacinar, Ferit

    2015-03-01

    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

  9. Risk assessment of gas oil and kerosene contamination on some properties of silty clay soil.

    PubMed

    Fallah, M; Shabanpor, M; Zakerinia, M; Ebrahimi, S

    2015-07-01

    Soil and ground water resource pollution by petroleum compounds and chemical solvents has multiple negative environmental impacts. The aim of this research was to investigate the impacts of kerosene and gas oil pollutants on some physical and chemical properties, breakthrough curve (BTC), and water retention curve (SWRC) of silty clay soil during a 3-month period. Therefore, some water-saturated soils were artificially contaminated in the pulse condition inside some glassy cylinders by applying half and one pore volume of these pollutants, and then parametric investigations of the SWRC were performed using RETC software for Van Genukhten and Brooks-Corey equations in the various suctions and the soil properties were determined before and after pollution during 3 months. The results showed that gas oil and kerosene had a slight effect on soil pH and caused the cumulative enhancement in the soil respiration, increase in the bulk density and organic matter, and reduction in the soil porosity and electrical and saturated hydraulic conductivity. Furthermore, gas oil retention was significantly more than kerosene (almost 40 %) in the soil. The survey of SWRC indicated that the contaminated soil samples had a little higher amount of moisture retention (just under 15 % in most cases) compared to the unpolluted ones during this 3-month period. The parametric analysis of SWRC demonstrated an increase in the saturated water content, ? s, from nearly 49 % in the control sample to just under 53 % in the polluted ones. Contaminants not only decreased the residual water content, ? r, but also reduced the SWRC gradient, n, and amount of ? parameter. The evaluation of both equations revealed more accurate prediction of SWRC's parameters by Van Genukhten compared to those of Brooks and Corey. PMID:26085279

  10. Application of three aquifer test methods for estimating hydraulic properties within the 100-N Area

    SciTech Connect

    Gilmore, T.J.; Spane, F.A. Jr.; Newcomer, D.R.; Sherwood, C.R.

    1992-12-01

    The purpose if this study was to better define the range of saturated horizontal hydraulic conductivities in the 100-N Area of the Hanford Site in southeastern Washington for use in a numerical groundwater model. Three methods were used for determining aquifer properties and are discussed within this report (1) reanalysis of past pumping test data using a pressure derivative method to identify the data in the radial flow regime for analysis by traditional graphical techniques, (2) sinusoidal analysis techniques described in Ferris that utilize water-table responses to river-level variations, and (3) the basic flow equation for groundwater.

  11. Correlating laboratory observations of fracture mechanical properties to hydraulically-induced microseismicity in geothermal reservoirs.

    SciTech Connect

    Stephen L. Karner, Ph.D

    2006-02-01

    To date, microseismicity has provided an invaluable tool for delineating the fracture network produced by hydraulic stimulation of geothermal reservoirs. While the locations of microseismic events are of fundamental importance, there is a wealth of information that can be gleaned from the induced seismicity (e.g. fault plane solutions, seismic moment tensors, source characteristics). Closer scrutiny of the spatial and temporal evolution of seismic moment tensors can shed light on systematic characteristics of fractures in the geothermal reservoir. When related to observations from laboratory experiments, these systematic trends can be interpreted in terms of mechanical processes that most likely operate in the fracture network. This paper reports on mechanical properties that can be inferred from observations of microseismicity in geothermal systems. These properties lead to interpretations about fracture initiation, seismicity induced after hydraulic shut-in, spatial evolution of linked fractures, and temporal evolution of fracture strength. The correlations highlight the fact that a combination of temperature, stressing rate, time, and fluid-rock interactions can alter the mechanical and fluid transport properties of fractures in geothermal systems.

  12. Hydraulic management in a soil moisture controlled SDI wastewater dispersal system in an Alabama black belt soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An experimental field moisture controlled subsurface drip irrigation (SDI) system was designed and installed as a field trial in a Vertisol in the Alabama Black Belt region for two years. The system was designed to start hydraulic dosing only when field moisture was below field capacity. Results sho...

  13. Relationships between induced polarization relaxation time and hydraulic properties of sandstone

    NASA Astrophysics Data System (ADS)

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

    2010-03-01

    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.

  14. Soil-water and soil physical properties under contour hedgerow systems on sloping oxisols

    Microsoft Academic Search

    F. Agus; D. K. Cassel; D. P. Garrity

    1997-01-01

    Hedgerows planted along the contour on steep lands in the humid tropics reduce soil erosion and build terraces over time. The objectives of this study in two Hapludoxes in the Philippines were to evaluate changes after 4 years in soil properties and soil water relations on transects perpendicular to the cropped alleys between four grass and tree hedgerow systems and

  15. IMPACT OF HIGH SOIL PHOSPHORUS LEVELS ON SOIL BIOLOGICAL ACTIVITY AND PHYSICAL PROPERTIES OF OXISOLS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    For the Cerrado region of Brazil to be agriculturally productive, large amount of P fertilizer must be added to overcome the P-fixation capacity of these Oxisol soils. Additions of large amounts of fertilizer affect the chemistry of the soil and may affect the soil physical and biological properties...

  16. SOYBEAN ROOT DISTRIBUTION RELATED TO CLAYPAN SOIL PROPERTIES AND APPARENT SOIL ELECTRICAL CONDUCTIVITY

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soybean [Glycine max (L.)] yield in claypan soils varies as a result of systematic relationships with soil properties and landscape position. This variability is likely caused by soil-landscape interactions with soybean roots. While much data exists on the landscape variability of yield, field obser...

  17. Understanding Hydraulic Property Rights Creation, Re Creation And De-Creation: A Case Study of Lorraine and Fumukwe Villages, Limpopo Basin

    Microsoft Academic Search

    P Sithole; B. van Koppen

    The paper seeks to examine and understand hydraulic property rights creation in two villages, Lorraine village in Sekororo (Olifants), South Africa, and Fumukwe village in Gwanda (Mzingwane) Zimbabwe. Unpacking and understanding hydraulic property rights creation in the two villages entail a rigorous analysis of how such property rights creation and the changes involved affect men and women; the nature and

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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.

  19. A Quantitative Assessment of the Influence of Structural Setting on Fault Hydraulic Property Distributions

    NASA Astrophysics Data System (ADS)

    Fairley, J. P.; Heffner, J.; Hinds, J. J.

    2003-12-01

    It is generally agreed that faults are an important control on groundwater flow, but relatively little work has been done to link structural setting with fault hydraulic properties at a level of detail appropriate for field-scale numerical modeling. The present study examines the influence of the structural setting on fault permeability by comparing spring temperature distributions from two geothermal areas in the Alvord Basin of southwest Oregon. Geothermal springs near the Borax Lake site occur along the trace of a normal fault, and appear to have developed a quasi-steady state spatial distribution. Geothermal vents in the Mickey Hot Springs area occur in a restricted zone between two fault splays; mean spring temperature at Mickey Hot Springs is significantly higher than at Borax Lake, and the center of spring activity shows evidence of migration with time. A geostatistical analysis of spring temperatures is used to quantify the differences in permeability distributions between the two sites, and illustrates the importance of including structural data in the development of realistic hydraulic property sets for numerical models of groundwater flow at fault-controlled sites.

  20. Predicting radiocaesium sorption characteristics with soil chemical properties for Japanese soils.

    PubMed

    Uematsu, Shinichiro; Smolders, Erik; Sweeck, Lieve; Wannijn, Jean; Van Hees, May; Vandenhove, Hildegarde

    2015-08-15

    The high variability of the soil-to-plant transfer factor of radiocaesium (RCs) compels a detailed analysis of the radiocaesium interception potential (RIP) of soil, which is one of the specific factors ruling the RCs transfer. The range of the RIP values for agricultural soils in the Fukushima accident affected area has not yet been fully surveyed. Here, the RIP and other major soil chemical properties were characterised for 51 representative topsoils collected in the vicinity of the Fukushima contaminated area. The RIP ranged a factor of 50 among the soils and RIP values were lower for Andosols compared to other soils, suggesting a role of soil mineralogy. Correlation analysis revealed that the RIP was most strongly and negatively correlated to soil organic matter content and oxalate extractable aluminium. The RIP correlated weakly but positively to soil clay content. The slope of the correlation between RIP and clay content showed that the RIP per unit clay was only 4.8mmolg(-1) clay, about threefold lower than that for clays of European soils, suggesting more amorphous minerals and less micaceous minerals in the clay fraction of Japanese soils. The negative correlation between RIP and soil organic matter may indicate that organic matter can mask highly selective sorption sites to RCs. Multiple regression analysis with soil organic matter and cation exchange capacity explained the soil RIP (R(2)=0.64), allowing us to map soil RIP based on existing soil map information. PMID:25897723

  1. Some Investigations on Cracking Characteristics of Soils

    Microsoft Academic Search

    Sudarshan B. Shinde

    Fine-grained soils, in particular, expansive soils are prone to cracking. For these soils swelling-shrinking potential is quite high and hence they exhibit adverse affect on overall stability of geotechnical structures. This phenomenon may also be responsible for alteration of various engineering properties of soils such as hydraulic conductivity, water and leachate penetration, solute transport, stability of slopes, etc. Previous studies

  2. ESTIMATION OF KOREAN PADDY FIELD SOIL PROPERTIES USING OPTICAL REFLECTANCE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An optical sensing approach based on diffuse reflectance has shown potential for rapid and reliable on-site estimation of soil properties. Important sensing ranges and the resulting regression models useful for soil property estimation have been reported. In this study, a similar approach was applie...

  3. SPATIAL CHARACTERISTICS OF CLAYPAN SOIL PROPERTIES IN AN AGRICULTURAL FIELD

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Spatial variability in soil properties has long been observed within uniformly–managed fields. Understanding the spatial characteristics of soil quality properties may help in the formulation of site–specific management plans. The primary objective of this study was to quantify the spatial character...

  4. Performance of lime-treated silty soil under long-term hydraulic conditions B. Le Runigoa

    E-print Network

    Paris-Sud XI, Université de

    a better homogeneity of the treatment, giving rise to a longer resistance to water circulation. Key-words to long-term hydraulic conditions (long-term water contact and water circulation) is still under and compaction conditions) on the lime treatment durability. The results showed that water contact leads

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

    E-print Network

    Naghshineh-Pour, Bijan

    1968-01-01

    (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...

  6. Active monitoring of hydraulic and mechanical properties variations during the hydraulic stimulation of a fractured porous reservoir: Some preliminary results from the HPPP Project

    NASA Astrophysics Data System (ADS)

    Cappa, F.; Guglielmi, Y.

    2010-12-01

    A new protocol of active geophysical monitoring is used to investigate the downhole changes in the hydromechanical response of a naturally porous reservoir layer with 80° dipping fractures where permeability was artificially enhanced by a hydraulic jacking test conducted by a step-wise increase of the fluid pressure. The protocol, called the High-Pulse Poroelasticity Protocol (HPPP) (http://hppp.unice.fr/), is focusing on controlled-impulsive source repeated observations and interpretation of rock properties changes over the seismic band of frequencies. The excitation source corresponds to a fast hydraulic pulse imposed in a small section of a borehole. The source is monitored with a special borehole probe based on fiber-optic sensors which allow dynamic fluid pressure/3D-mechanical deformation measurements, with reflection of light at specific wavelength from Fabry-Pérot or fiber Bragg gratings mounted between inflatable packers. Within the injection zone, fluid pressure and deformation waves of 1 to 500 Hz and static hydraulic diffusion are simultaneously measured to quantify the hydromechanical couplings Two identical pressure pulses were performed to test the rock three-dimensionnal mechanical response before and after the jacking test. It clearly appears that (1) the magnitude of the rock deformation is a factor of 3 higher, and (2) the principal deformation component pitch is rotated of about 20° with more radial deformation of the layer after the jacking test. Those preliminary tests show that the HPPP protocol can actively improve downhole monitoring of both hydraulic and mechanical bulk properties changes of rocks under strong dynamic stress-flow couplings.

  7. Hydraulic and anatomical properties of light bands in Norway spruce compression wood.

    PubMed

    Mayr, Stefan; Bardage, Stig; Brändström, Jonas

    2006-01-01

    Compression wood (CW), which is formed on the underside of conifer branches, exhibits a lower specific hydraulic conductivity (k(s)) compared with normal wood. However, the first-formed tracheids of an annual ring on the underside of a conifer branch often share several properties with normal tracheids, e.g., thin cell walls and angular cross sections. These first-formed tracheids appear bright when observed by the naked eye and are therefore called light bands (LB). In this study, hydraulic and related anatomical properties of LBs were characterized and compared with typical CW and opposite wood (OW). Measurements were made on branches of Norway spruce (Picea abies (L.) Karst.). Specific hydraulic conductivity was measured with fine cannulas connected to microlitre syringes. Micro- and ultrastructural analysis were performed on transverse and radial longitudinal sections by light and scanning electron microscopy. Xylem areas containing both typical CW and LBs had a k(s) 51.5% that of OW (7.95 +/- 0.97 m(2) s(-1) MPa(-1) x 10(-4)), whereas k(s) of pure CW was only 26.7% that of OW. The k(s) of LBs (6.38 +/- 0.97 m(2) s(-1) MPa(-1) x 10(-4); 80.3% of OW) was estimated from these k(s) values because the cannulas were too wide to measure the k(s) of LBs directly. Mean lumen area of first-formed tracheids on the underside of branches was 65.7% that of first-formed tracheids in OW and about three times that of CW. Light-band tracheids exhibited a bordered pit frequency of 42.7 +/- 1.3 pits mm(-1), which was three times that in CW and 1.6 times that in OW. Bordered pit apertures in LB tracheids (9.15 +/- 0.60 microm(2)) were 1.7 times wider than those in CW and similar in aperture to those in OW. The high k(s) of LBs was correlated with their wide tracheid lumina, high pit frequency and wide pit apertures. We therefore suggest that LBs have a primarily hydraulic function within the mechanically optimized CW region. This might be important for supplying water to living tissues on the underside of branches, as well as to other distal areas along water transport pathways following the spiral grain of wood. PMID:16203710

  8. Organic solvent alteration of hydraulic properties of sedimentary rocks of low permeability: a review

    SciTech Connect

    Sklarew, D.S.

    1985-05-01

    A review of the current literature on hydrophysical interactions of organic solutes with sedimentary rocks of low permeability is presented. The motivation was the premise that low permeability rocks may act as secondary (aquifer) barriers for the containment of hazardous organic wastes, thus preventing these wastes from contaminating the groundwater. However, this premise may be incorrect if organic wastes can affect the hydraulic conductivity of these rocks. The results indicate that very little work has been done concerning interactions of organics with consolidated subsurface materials. Available information on three related topics was summarized: the effect of organic compounds on the hydrophysical properties of clays, case studies concerning the interactions of organic compounds with clays and sedimentary rocks, and the effect of shales on inorganic transport. These studies give an indication of some research areas that need to be explored with regard to the effect of organic compounds on the hydrophysical properties of sedimentary rocks; these research needs are briefly summarized. 42 refs.

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

    PubMed Central

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

    2003-01-01

    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

  10. Strip-tillage effect on seedbed soil temperature and other soil physical properties

    Microsoft Academic Search

    Mark A. Licht; Mahdi Al-Kaisi

    2005-01-01

    The no-tillage system is perceived as having lower soil temperatures, wetter soil conditions, and greater surface penetration resistance compared with conventional and other conservation tillage systems. Concerns associated with the effect of the no-tillage system on certain soil physical properties (i.e. soil temperature, moisture, and compaction) prompted this study to evaluate the effect of an alternative tillage system, strip-tillage, on

  11. Hydrological properties of natural and reconstituted soils: compared methods.

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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

  12. Physical and Hydraulic Properties of Rock Specimens from Grimsel Test Site, Switzerland

    NASA Astrophysics Data System (ADS)

    Zhang, M.; Takeda, M.

    2007-12-01

    The Grimsel Test Site (GTS) is located at an altitude of 1730 meters in the granite rock of Aar Massif in central Switzerland. It lies at a depth of around 450 meters beneath the surface and was established over 20 years ago by the National Cooperative for the Disposal of Radioactive Waste (Nagra) as a center for underground Research and Development (R&D) supporting a wide range of related research projects. Among many of them, an international cooperative project defined as the Long Term Diffusion (LTD) has been performing to obtain quantitative information on matrix diffusion in rock strata under in-situ conditions. A set of laboratory experiments is also planed to determine the physical, hydraulic and diffusive transport properties of rock specimens taken from the same test site. In this poster, we present the preliminary results of both physical and hydraulic properties of the rock specimens being tested, including the bulk density, porosity, specific surface area and pore distribution, microstructure, P and S wave velocities, electrical resistivity, air and water permeabilities. The results obtained in this study indicate that: 1) The porosity and wave velocities of Grimsel granite are relatively low compared to the average values of igneous rocks indicating that micro-cracks can potentially exist within grain minerals. 2) The air and water permeabilities obtained from the air and water permeability tests are consistent that illustrates the accuracy of both experiments. 3) Permeability is not a simple function of effective confining pressure. It is very sensitive to confining pressure especially at low pressure levels. Besides, the permeability is hysteretic depending on confining pressure, pore pressure and stress history. 4) Similar to the hydraulic properties, diffusive transport properties of rock specimens can also be significantly affected by the confining pressure conditions. Laboratory diffusion tests considering the effects of stress conditions are fundamentally necessary for predicting the process of in-situ diffusion test and for comparing the results to be obtained from the in situ tests in the near future. Acknowledgement: This research project has been conducted under the research contract with the Japan Nuclear Energy Safety Organization (JNES).

  13. Soil Properties Controlling Zn Speciation and Fractionation in Contaminated Soils

    SciTech Connect

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

    2009-01-01

    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.

  14. Biotic and Abiotic Soil Properties Influence Survival of Listeria monocytogenes in Soil

    PubMed Central

    Locatelli, Aude; Spor, Aymé; Jolivet, Claudy; Piveteau, Pascal; Hartmann, Alain

    2013-01-01

    Listeria monocytogenes is a food-borne pathogen responsible for the potentially fatal disease listeriosis and terrestrial ecosystems have been hypothesized to be its natural reservoir. Therefore, identifying the key edaphic factors that influence its survival in soil is critical. We measured the survival of L. monocytogenes in a set of 100 soil samples belonging to the French Soil Quality Monitoring Network. This soil collection is meant to be representative of the pedology and land use of the whole French territory. The population of L. monocytogenes in inoculated microcosms was enumerated by plate count after 7, 14 and 84 days of incubation. Analysis of survival profiles showed that L. monocytogenes was able to survive up to 84 days in 71% of the soils tested, in the other soils (29%) only a short-term survival (up to 7 to 14 days) was observed. Using variance partitioning techniques, we showed that about 65% of the short-term survival ratio of L. monocytogenes in soils was explained by the soil chemical properties, amongst which the basic cation saturation ratio seems to be the main driver. On the other hand, while explaining a lower amount of survival ratio variance (11%), soil texture and especially clay content was the main driver of long-term survival of L. monocytogenes in soils. In order to assess the effect of the endogenous soils microbiota on L. monocytogenes survival, sterilized versus non-sterilized soils microcosms were compared in a subset of 9 soils. We found that the endogenous soil microbiota could limit L. monocytogenes survival especially when soil pH was greater than 7, whereas in acidic soils, survival ratios in sterilized and unsterilized microcosms were not statistically different. These results point out the critical role played by both the endogenous microbiota and the soil physic-chemical properties in determining the survival of L. monocytogenes in soils. PMID:24116083

  15. A global data set of soil particle size properties

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

    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.

  16. Hydraulic root water uptake models: old concerns and new insights

    NASA Astrophysics Data System (ADS)

    Couvreur, V.; Carminati, A.; Rothfuss, Y.; Meunier, F.; Vanderborght, J.; Javaux, M.

    2014-12-01

    Root water uptake (RWU) affects underground water dynamics, with consequences on plant water availability and groundwater recharge. Even though hydrological and climate models are sensitive to RWU parameters, no consensus exists on the modelling of this process. Back in the 1940ies, Van Den Honert's catenary approach was the first to investigate the use of connected hydraulic resistances to describe water flow in whole plants. However concerns such as the necessary computing when architectures get complex made this approach premature. Now that computing power increased dramatically, hydraulic RWU models are gaining popularity, notably because they naturally produce observed processes like compensatory RWU and hydraulic redistribution. Yet major concerns remain. Some are more fundamental: according to hydraulic principles, plant water potential should equilibrate with soil water potential when the plant does not transpire, which is not a general observation when using current definitions of bulk or average soil water potential. Other concerns regard the validation process: water uptake distribution is not directly measurable, which makes it hard to demonstrate whether or not hydraulic models are more accurate than other models. Eventually parameterization concerns exist: root hydraulic properties are not easily measurable, and would even fluctuate on an hourly basis due to processes like aquaporin gating. While offering opportunities to validate hydraulic RWU models, newly developed observation techniques also make us realize the increasing complexity of processes involved in soil-plant hydrodynamics, such as the change of rhizosphere hydraulic properties with soil drying. Surprisingly, once implemented into hydraulic models, these processes do not necessarily translate into more complex emerging behavior at plant scale, and might justify the use of simplified representations of the soil-plant hydraulic system.

  17. The Importance of Deep Roots and Hydraulic Redistribution on Vegetation and Soil Responses to Hydro-Climatic Variability: A Simulation Analysis

    Microsoft Academic Search

    Darren Drewry; Praveen Kumar; Murugesu Sivapalan

    2010-01-01

    Vegetation is fundamentally coupled to the soil through the uptake of moisture and nutrients that regulate carbon, water and energy exchange with the atmosphere. Along with the biological and physical characteristics of the above-ground vegetation, rooting depth and the vertical distribution of root biomass play a critical role in vegetation functioning by controlling access to resources. Hydraulic redistribution (HR), the

  18. Spatial Variations in Soil Properties at the University of Mississippi Soil Moisture Observatory

    NASA Astrophysics Data System (ADS)

    Holland, J. V.; Fancher, C. W.; Sleep, M. D.; Twombly, J. E.; Aufman, M. S.; Holt, R. M.; Kuszmaul, J. S.

    2004-05-01

    Geophysical and remote sensing technologies are being increasingly used to investigate the properties of shallow soils. Nearly all of the soil physical properties important to geophysical and remote sensing technologies, including electrical conductivity, electromagnetic properties, thermal properties, acoustic properties, and vapor phase transport processes, are controlled by soil mineralogy, soil structure, and the distribution of soil moisture. Spatial and temporal variations in these controls conspire to confound sensor observations and complicate data reduction and inversion by producing non-unique sensor signatures. To provide a facility for detailed study of soil - geophysical interactions, we are constructing a Soil Moisture Observatory (SMO) at the University of Mississippi (UM). The 5 acre SMO is located in a former agricultural field at the UM Biological Field Station, a 740 acre tract of land located 11 miles from the UM campus in Oxford, Mississippi. The soils present at the SMO consist of silty and sandy loam. Our preliminary activities at the site included collecting 60 continuous soil cores using a direct-push sampling probe and the installation of neutron access tubes along two intersecting transects. Continuous soil samples were taken to a depth of 1.5 m and analyzed for particle size distribution, porosity, bulk density, iron content, moisture content. Variograms of these data show that most soil properties have a horizontal correlation length of greater than 10 m. The horizontal correlation length for moisture content increases with depth from about 12 m near the soil surface to approximately 24 m at a depth of 1 m. Vertical variograms of soil moisture show evidence of a small-scale structure with a correlation length of 0.6 m.

  19. Evolution of black carbon properties in soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Black carbon deposited in soil from natural or deliberate wildfires and engineered black carbon products (biochar) intentionally added to soil are known to have significant effects on soil biogeochemical processes and in many cases to influence the yield and quality of crops and to enhance the abili...

  20. Modelling long term biodenitrification processes from column experiments: Insight in how feeding strategy affect hydraulic properties

    NASA Astrophysics Data System (ADS)

    Rodríguez-Escales, Paula; Folch, Albert; van Breukelen, Boris; Vidal-Gavilan, Georgina; Sanchez-Vila, Xavier

    2015-04-01

    We developed a reactive transport model that reproduced a 342 days long laboratory column experiment of biodenitrification processes with different injection strategies in terms of frequency (daily, weekly) and C:N ratio. Furthermore, we evaluated changes in hydraulic properties as result of biodenitrification. It was found that biodenitrification promoted the transition from normal to anomalous (non-Fickian) transport due to the increase of heterogeneity in hydraulic parameters. Comparing the breakthrough curves from two conservative bromide tracer tests performed at the beginning and at the end of the experiment, two significant features were observed: first, an increase in dispersivity, and second, a transition from a curve that can be modeled with an advection-dispersion equation to a different one that can be modeled using a dual domain mass transfer model. This behavior is associated to the presence of a diffusive layer promoted by biofilm growth during the last 100 days of the experiment. Regarding the injection conditions, it was found that besides other parameters described in the literature (nutrient loading, flow rate, and grain size), injection frequency significantly modifies dispersivity, being largest for continuous injection. Moreover, reducing the C:N ratio for optimizing costs was possible after a substantial biomass developed. A careful design of injection conditions and substrate rates can then be devised in specific cases to promote biodenitrification.

  1. Simulation and verification of hydraulic properties and organic matter degradation in sand filters for greywater treatment.

    PubMed

    Karlsson, Susanna Ciuk; Langergraber, G; Pell, M; Dalahmeh, S; Vinnerås, B; Jönsson, H

    2015-01-01

    To evaluate the treatment performance of vertical flow sand filters, the HYDRUS wetland module was used to simulate treatment in an experimental set-up. The laboratory filters were intermittently dosed with artificial greywater at a hydraulic loading rate of 0.032 m(3) m(-2) day(-1) and an organic loading rate of 0.014 kg BOD5 m(-2) day(-1). The hydraulic properties of the filter were characterised, as were inflow and outflow concentrations of chemical oxygen demand (COD), biochemical oxygen demand (BOD), ammonia, nitrate and total nitrogen. The inverse simulation function of the HYDRUS software was used to calibrate the water flow model. The observed effect of water flowing faster along the column wall was included in the inverse simulations. The biokinetic model was calibrated by fitting heterotrophic biomass growth to measurements of potential respiration rate. Emphasis was put on simulating outflow concentrations of organic pollutants. The simulations were conducted using three models of varying degree of calibration effort and output accuracy. The effluent concentration was 245 mg COD L(-1) for the laboratory filters, 134 mg COD mg L(-1) for the model excluding wall flow effects and 338 mg COD mg L(-1) for the model including wall flow effects. PMID:25714643

  2. Two-well test method for determining hydraulic properties of aquifers

    SciTech Connect

    Clement, T.P.; Truex, M.J.; Hooker, B.S. [Pacific Northwest National Lab., Richland, WA (United States)

    1997-07-01

    A steady-state test to determine the hydraulic properties of an aquifer is presented. The test uses an injection-extraction well-pair to establish a two-dimensional, steady-state flow field in the tested region. At least one observation well is needed to measure the hydraulic head within the flow field. Depending on the number of observation wells, a single-observation-well method or a distance-head method is used to analyze the head data. Two field examples demonstrate the potential application of the test. The field experiments were done at the US Department of Energy Hanford site near Richland, Washington. The two-well test procedure described in this work provides a useful alternative for characterizing aquifers while deploying in situ ground-water remediation systems. One of the most attractive features of this test, especially at contaminated aquifers, is that there is no water to dispose. The test is simple and economical, and it also avoids several other limitations associated with typical pumping or slug tests.

  3. A comparison of hydraulic conductivities, permeabilities and infiltration rates in frozen and unfrozen soils

    Microsoft Academic Search

    Craig A McCauley; Daniel M White; Michael R Lilly; David M Nyman

    2002-01-01

    In order to protect water resources, fuel-storage facilities in Alaska are required to provide secondary containment for fuel spills. Secondary containment generally consists of a lined catchment basin. The lining must have a hydraulic conductivity of less than 1e?6 cm\\/s [ADEC, 1996. Alaska Department of Environmental Conservation Division of Spill Prevention and Response Industry Preparedness and Pipeline Program. “Sufficiently Impermeable

  4. Influence of Natural Fractures Cohesive Properties on Geometry of Hydraulic Fracture Networks

    NASA Astrophysics Data System (ADS)

    Gonzalez-Chavez, M. A.; Dahi Taleghani, A.; Puyang, P.

    2014-12-01

    An integrated modeling methodology is proposed to analyze hydraulic fracturing jobs in the presence of the natural fracture network in the formation. A propagating hydraulic fracture may arrest, cross, or diverts into a preexisting natural crack depending on fracture properties of rock and magnitude and direction of principal rock stresses. Opening of natural fractures during fracturing treatment could define the effectiveness of the stimulation technique. Here, we present an integrated methodology initiated with lab scale fracturing properties using Double Cantilever Beam tests (DCB) to determine cohesive properties of rock and natural fractures. We used cohesive finite element models to reproduce laboratory results to verify the numerical model for the interaction of the hydraulic fracture and individual cemented natural fractures. Based on the initial investigations, we found out that distribution of pre-existing natural fractures could play a significant role in the final geometry of the induced fracture network; however in practice, there is not much information about the distribution of natural fractures in the subsurface due to the limited access. Hence, we propose a special optimization scheme to generate natural fracture geometry from the location of microseismic events. Accordingly, the criteria of evaluating the fitness of natural fracture realizations is defined as the total minimum distance squares of all microseismic events, which is the sum of minimum square distance for all microseismic events. Moreover, an additional constraint in this problem is that we need to set a minimum distance between fracture grids. Using generated natural fracture realizations, forward field-scale simulations are implemented using cohesive finite element analysis to find the best match with the recorded bottomhole pressure. To show the robustness of the proposed workflow for real field problem, we implemented this technique on available data from several well Chicontepec basin to forecast post-treatment production rate. Our results show a constructive approach to integrate microseismic maps with lab mechanical measurements and bottomhole pressure to estimate the geometry of induced fracture network in the subsurface which does not suffer from any limiting assumption about fracture geometries.

  5. Effect of Salinity, Sodicity and Soil Texture on Aggregate Stability of Semi-arid Soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil texture, sodicity and salinity or water quality play a significant role in determining soil aggregate stability, hydraulic properties and the response of soil clays to dispersion and swelling. We studied aggregate stability from 60 samples of Israeli top soils, widely varying in clay content an...

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

    USGS Publications Warehouse

    Schaap, Bryan D.

    2000-01-01

    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

  7. Intelligent estimation of spatially distributed soil physical properties

    USGS Publications Warehouse

    Iwashita, F.; Friedel, M.J.; Ribeiro, G.F.; Fraser, Stephen J.

    2012-01-01

    Spatial analysis of soil samples is often times not possible when measurements are limited in number or clustered. To obviate potential problems, we propose a new approach based on the self-organizing map (SOM) technique. This approach exploits underlying nonlinear relation of the steady-state geomorphic concave-convex nature of hillslopes (from hilltop to bottom of the valley) to spatially limited soil textural data. The topographic features are extracted from Shuttle Radar Topographic Mission elevation data; whereas soil textural (clay, silt, and sand) and hydraulic data were collected in 29 spatially random locations (50 to 75. cm depth). In contrast to traditional principal component analysis, the SOM identifies relations among relief features, such as, slope, horizontal curvature and vertical curvature. Stochastic cross-validation indicates that the SOM is unbiased and provides a way to measure the magnitude of prediction uncertainty for all variables. The SOM cross-component plots of the soil texture reveals higher clay proportions at concave areas with convergent hydrological flux and lower proportions for convex areas with divergent flux. The sand ratio has an opposite pattern with higher values near the ridge and lower values near the valley. Silt has a trend similar to sand, although less pronounced. The relation between soil texture and concave-convex hillslope features reveals that subsurface weathering and transport is an important process that changed from loss-to-gain at the rectilinear hillslope point. These results illustrate that the SOM can be used to capture and predict nonlinear hillslope relations among relief, soil texture, and hydraulic conductivity data. ?? 2011 Elsevier B.V.

  8. A transient laboratory method for determining the hydraulic properties of 'tight' rocks-I. Theory

    USGS Publications Warehouse

    Hsieh, P.A.; Tracy, J.V.; Neuzil, C.E.; Bredehoeft, J.D.; Silliman, S.E.

    1981-01-01

    Transient pulse testing has been employed increasingly in the laboratory to measure the hydraulic properties of rock samples with low permeability. Several investigators have proposed a mathematical model in terms of an initial-boundary value problem to describe fluid flow in a transient pulse test. However, the solution of this problem has not been available. In analyzing data from the transient pulse test, previous investigators have either employed analytical solutions that are derived with the use of additional, restrictive assumptions, or have resorted to numerical methods. In Part I of this paper, a general, analytical solution for the transient pulse test is presented. This solution is graphically illustrated by plots of dimensionless variables for several cases of interest. The solution is shown to contain, as limiting cases, the more restrictive analytical solutions that the previous investigators have derived. A method of computing both the permeability and specific storage of the test sample from experimental data will be presented in Part II. ?? 1981.

  9. Magnetic properties of alluvial soils polluted with heavy metals

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

    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.

  10. Effect of land use change on soil properties and functions

    NASA Astrophysics Data System (ADS)

    Tonutare, Tonu; Kõlli, Raimo; Köster, Tiina; Rannik, Kaire; Szajdak, Lech; Shanskiy, Merrit

    2014-05-01

    For good base of sustainable land management and ecologically sound protection of soils are researches on soil properties and functioning. Ecosystem approach to soil properties and functioning is equally important in both natural and cultivated land use conditions. Comparative analysis of natural and agro-ecosystems formed on similar soil types enables to elucidate principal changes caused by land use change (LUC) and to elaborate the best land use practices for local pedo-ecological conditions. Taken for actual analysis mineral soils' catena - rendzina ? brown soils ? pseudopodzolic soils ? gley-podzols - represent ca 1/3 of total area of Estonian normal mineral soils. All soils of this catena differ substantially each from other by calcareousness, acidity, nutrition conditions, fabric and humus cover type. This catena (representative to Estonian pedo-ecological conditions) starts with drought-prone calcareous soils. Brown (distributed in northern and central Estonia) and pseudopodzolic soils (in southern Estonia) are the most broadly acknowledged for agricultural use medium-textured high-quality automorphic soils. Dispersedly distributed gley-podzols are permanently wet and strongly acid, low-productivity sandy soils. In presentation four complex functions of soils are treated: (1) being a suitable soil environment for plant cover productivity (expressed by annual increment, Mg ha-1 yr-1); (2) forming adequate conditions for decomposition, transformation and conversion of fresh falling litter (characterized by humus cover type); (3) deposition of humus, individual organic compounds, plant nutrition elements, air and water, and (4) forming (bio)chemically variegated active space for soil type specific edaphon. Capacity of soil cover as depositor (3) depends on it thickness, texture, calcareousness and moisture conditions. Biological activity of soil (4) is determined by fresh organic matter influx, quality and quantity of biochemical substances and humus, and pedo-ecological conditions. LUC from natural to arable is accompanied by different regulations: (1) regular restoration of plant available nutrition elements' stocks in soil, (2) regulation (if needed) of water regime of gleyed and gley soils, (3) optimizing of soil actual acidity by liming, and (4) forming a suitable for crops seed bed instead of natural epipedon. Principal changes are occurred in fabric and agrochemical properties of topsoil and in soil functioning. The connected with LUC changes in soil functioning are: (1) increase of openness level of chemical elements cycling and nutrition elements concentration in phytomass, and (2) decrease of total phytomass, species diversity, amount of annual falling litter and content of mortmass in soil cover. These changes lead to decreasing of biological control on soil resources, flux of energy and substances to soil processes, and volume of cycling. At the same time the intensity of organic matter decomposition and outflow of nutrition elements are increased. All these changes are resulted by alteration of food chains and exhausting of nutrition elements' stocks. The changes in soil functioning (decrease or increase of productivity) depend much on soil type. The aspects of functioning, which do not changed with LUC are chemical-textural potential of soil cover and functioning character of subsoil. The sound matching of soil and plant cover is of decisive importance for sustainable functioning of ecosystem and in attaining a good environmental status of the area.

  11. Ice nucleation properties of agricultural soil dusts

    NASA Astrophysics Data System (ADS)

    Steinke, Isabelle; Funk, Roger; Busse, Jacqueline; Iturri, Antonela; Kirchen, Silke; Leue, Martin; Möhler, Ottmar; Schwartz, Thomas; Sierau, Berko; Toprak, Emre; Ulrich, Andreas; Hoose, Corinna; Leisner, Thomas

    2015-04-01

    Soil dust particles emitted from agricultural areas contain large amounts of organic material such as fungi, bacteria and plant debris. Being carrier for potentially highly ice-active biological particles, agricultural soil dusts are candidates for being very ice-active as well. In this work, we present ice nucleation experiments conducted in the AIDA cloud chamber. We investigated the ice nucleation efficiency of four types of soil dust from different regions of the world. Results are presented for the immersion freezing and the deposition nucleation mode: all soil dusts show higher ice nucleation efficiencies than desert dusts, especially at temperatures above 254 K. For one soil dust sample, the effect of heat treatments was investigated. Heat treatments did not affect the ice nucleation efficiency which presumably excludes primary biological particles as the only source of the increased ice nucleation efficiency. Therefore, organo-mineral complexes or organic compounds may contribute substantially to the high ice nucleation activity of agricultural soil dusts.

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

    PubMed Central

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

    2012-01-01

    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

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

    E-print Network

    Paris-Sud XI, Université de

    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

  14. Determination of pore size distribution and hydraulic properties using nuclear magnetic resonance relaxometry: A comparative study of laboratory methods

    Microsoft Academic Search

    L. R. Stingaciu; L. Weihermüller; S. Haber-Pohlmeier; S. Stapf; H. Vereecken; A. Pohlmeier

    2010-01-01

    In this study, we evaluate the feasibility of using nuclear magnetic resonance (NMR) relaxometry measurements to characterize pore size distribution and hydraulic properties in four porous samples with different texture and composition. We compare NMR with two classical techniques based on water retention and mercury intrusion measurements. Both T2 and T1 NMR relaxation measurements at 6.47 MHz were carried out

  15. Estimating Soil Cation Exchange Capacity from Soil Physical and Chemical Properties

    NASA Astrophysics Data System (ADS)

    Bateni, S. M.; Emamgholizadeh, S.; Shahsavani, D.

    2014-12-01

    The soil Cation Exchange Capacity (CEC) is an important soil characteristic that has many applications in soil science and environmental studies. For example, CEC influences soil fertility by controlling the exchange of ions in the soil. Measurement of CEC is costly and difficult. Consequently, several studies attempted to obtain CEC from readily measurable soil physical and chemical properties such as soil pH, organic matter, soil texture, bulk density, and particle size distribution. These studies have often used multiple regression or artificial neural network models. Regression-based models cannot capture the intricate relationship between CEC and soil physical and chemical attributes and provide inaccurate CEC estimates. Although neural network models perform better than regression methods, they act like a black-box and cannot generate an explicit expression for retrieval of CEC from soil properties. In a departure with regression and neural network models, this study uses Genetic Expression Programming (GEP) and Multivariate Adaptive Regression Splines (MARS) to estimate CEC from easily measurable soil variables such as clay, pH, and OM. CEC estimates from GEP and MARS are compared with measurements at two field sites in Iran. Results show that GEP and MARS can estimate CEC accurately. Also, the MARS model performs slightly better than GEP. Finally, a sensitivity test indicates that organic matter and pH have respectively the least and the most significant impact on CEC.

  16. 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...

  17. Measurement of soil thermal properties by spherical probe

    Microsoft Academic Search

    Stanko Milun; Tomislav Kilic ´; Ozren Bego

    2005-01-01

    The thermal resistivity of the soil surrounding a power cable is a very important factor in evaluating the load-carrying capability of underground cable. This paper presents a method for measurements of soil thermal properties with a spherical probe along the cable installation routes. On the basis of two-port network analysis, equations for the temperature response of the hollow spherical probe

  18. Effects of fire on properties of forest soils: a review

    Microsoft Academic Search

    Giacomo Certini

    2005-01-01

    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,

  19. Soil property changes: a 60 -year record from California

    Microsoft Academic Search

    CLERCK Fabrice; LINDERT Peter

    How has soil quality changed in California over the past 60 years? Using known locations of archived samples collected by the soil survey staff in the 1940's and 50's we resampled 125 locations in California from the Imperial Valley in the south to Tehama county in the north and analyzed samples for properties important to plant production. For each 1945

  20. Importance of soil-water relation in assessment endpoint in bioremediated soils: Plant growth and soil physical properties

    SciTech Connect

    Li, X.; Sawatsky, N. [Alberta Environmental Centre, Vegreville, Alberta (Canada)

    1995-12-31

    Much effort has been focused on defining the end-point of bioremediated soils by chemical analysis (Alberta Tier 1 or CCME Guideline for Contaminated Soils) or toxicity tests. However, these tests do not completely assess the soil quality, or the capability of soil to support plant growth after bioremediation. This study compared barley (Hordeum vulgare) growth on: (i) non-contaminated, agricultural topsoil, (2) oil-contaminated soil (4% total extractable hydrocarbons, or TEH), and (3) oil-contaminated soil treated by bioremediation (< 2% TEH). Soil physical properties including water retention, water uptake, and water repellence were measured. The results indicated that the growth of barley was significantly reduced by oil-contamination of agricultural topsoil. Furthermore, bioremediation did not improve the barley yield. The lack of effects from bioremediation was attributed to development of water repellence in hydrocarbon contaminated soils. There seemed to be a critical water content around 18% to 20% in contaminated soils. Above this value the water uptake by contaminated soil was near that of the agricultural topsoil. For lower water contents, there was a strong divergence in sorptivity between contaminated and agricultural topsoil. For these soils, water availability was likely the single most important parameter controlling plant growth. This parameter should be considered in assessing endpoint of bioremediation for hydrocarbon contaminated soils.

  1. Influence of water table level and soil properties on emissions of greenhouse gases from cultivated peat soil

    Microsoft Academic Search

    Ö. Berglund; K. Berglund

    2011-01-01

    A lysimeter method using undisturbed soil columns was used to investigate the effect of water table depth and soil properties on soil organic matter decomposition and greenhouse gas (GHG) emissions from cultivated peat soils. The study was carried out using cultivated organic soils from two locations in Sweden: Örke, a typical cultivated fen peat with low pH and high organic

  2. Does the soil's effective hydraulic conductivity adapt in order to obey the Maximum Entropy Production principle? A lab experiment

    NASA Astrophysics Data System (ADS)

    Westhoff, Martijn; Zehe, Erwin; Erpicum, Sébastien; Archambeau, Pierre; Pirotton, Michel; Dewals, Benjamin

    2015-04-01

    The Maximum Entropy Production (MEP) principle is a conjecture assuming that a medium is organized in such a way that maximum power is subtracted from a gradient driving a flux (with power being a flux times its driving gradient). This maximum power is also known as the Carnot limit. It has already been shown that the atmosphere operates close to this Carnot limit when it comes to heat transport from the Equator to the poles, or vertically, from the surface to the atmospheric boundary layer. To reach this state close to the Carnot limit, the effective thermal conductivity of the atmosphere is adapted by the creation of convection cells (e.g. wind). The aim of this study is to test if the soil's effective hydraulic conductivity also adapts itself in such a way that it operates close to the Carnot limit. The big difference between atmosphere and soil is the way of adaptation of its resistance. The soil's hydraulic conductivity is either changed by weathering processes, which is a very slow process, or by creation of preferential flow paths. In this study the latter process is simulated in a lab experiment, where we focus on the preferential flow paths created by piping. Piping is the process of backwards erosion of sand particles subject to a large pressure gradient. Since this is a relatively fast process, it is suitable for being tested in the lab. In the lab setup a horizontal sand bed connects two reservoirs that both drain freely at a level high enough to keep the sand bed always saturated. By adding water to only one reservoir, a horizontal pressure gradient is maintained. If the flow resistance is small, a large gradient develops, leading to the effect of piping. When pipes are being formed, the effective flow resistance decreases; the flow through the sand bed increases and the pressure gradient decreases. At a certain point, the flow velocity is small enough to stop the pipes from growing any further. In this steady state, the effective flow resistance of the sand bed will be compared with the theoretical optimal flow resistance obtained with the MEP principle. For this study, different magnitudes of the forcing will be tested, while also the effect of dry spells will be explored.

  3. Winter conditions and their effects on soil properties and spring erosion on agricultural soils - first results and outlook on further work

    NASA Astrophysics Data System (ADS)

    Starkloff, Torsten

    2015-04-01

    In the Scandinavian countries, the highest levels of soil erosion on agricultural land are usually measured during the spring period. During the end of the winter, snowmelt combined with heavy rains often lead to sever erosion on agricultural soils. The severity of erosion is often determined by the winter conditions, which effect certain soil properties (i.e. infiltration capabilities, structure and surface morphology) and the snow pack properties during snow melt. To reduce spring erosion by implementing suitable mitigation measures it is necessary to have a better understanding of these processes that occur during winter at a catchment scale.The first step in this study was to understand the change in infiltration capabilities, frost development and change in soil temperature of the two main soils in the study catchment during soil freezing and thawing. To do that six 50 cm x 20 cm soil cylinders equipped with 4 TDR/temperature probes where installed in the field, three on each soil type. The obtained data together with measured soil water retention characteristics and other soil physical parameters (i.e. bulk density, organic matter content, soil texture) were then used to calibrate and validate a hydrogeological model (Hydrus 1D). The purpose of this was to gain a better process understanding and validate if the model could be used to produce input parameters (e.g. saturated soil hydraulic conductivity) for later applied soil erosion modelling under different winter conditions. The results showed that the two soil types reacted differently to changing winter conditions.We also found that Hydrus model was capable of reproducing the measured values in an acceptable error range and can be further used to calculate input values for different winter conditions for the soil type investigated in this study.To improve our understanding of the processes that lead to spring erosion at a catchment scale further we now aim to use a variety of methods. We intend to investigate; (1) the heterogeneity of the snow pack on a catchments scale during winter and snow melt by use of remote sensing (i.e. airborne photogrammetry) and 35 snow depth measuring poles distributed over the catchment. (2) The effect of slope, aspect and curvature on infiltration processes and frost development during winter using electronically resistivity measurements (ERT). (3) Lateral flow processes in snow packs in a Laboratory experiment and (4) the change in macro pore structure due to freezing and thawing using X-ray computed tomography.

  4. Soil properties and soil water conditions in the yangjuangou catchment of the chinese loess plateau

    Microsoft Academic Search

    U Schindler; Y Li; R Funk

    2004-01-01

    Soil properties and soil water conditions were assessed for different land use (forest, arable land, grassland) on a silty Calcaric Regosol in the Yangjuangou Catchment of the Chinese Loess Plateau. The loess here is unimodal, poorly sorted with abundant coarse silt, has very low dry bulk density (1.11?–?1.38?g cm) and little organic carbon content (1.6?–?3.7?g kg). The soils are hydrophilic,

  5. Soil biochemical properties after six years in amended brown and gray mine soils in West Virginia

    NASA Astrophysics Data System (ADS)

    Thomas, C.; Sexstone, A.; Skousen, J.

    2015-06-01

    Surface coal mining in the eastern USA disturbs hundreds of hectares of land every year and removes valuable and ecologically diverse eastern deciduous forests. Reclamation involves restoring the landscape to approximate original contour, replacing the topsoil, and revegetating the site with trees and herbaceous species to a designated post-mining land use. Re-establishing an ecosystem of ecological and economic value as well as restoring soil quality on disturbed sites are the goals of land reclamation, and microbial properties of mine soils can be indicators of restoration success. Reforestation plots were constructed in 2007 using weathered brown sandstone or unweathered gray sandstone as topsoil substitutes to evaluate tree growth and soil properties at Arch Coal's Birch River Mine in West Virginia, USA. All plots were planted with 12 hardwood tree species and subplots were hydroseeded with an herbaceous seed mix and fertilizer. After six years, average tree volume index was nearly ten times greater for trees grown in brown (3853 cm3) compared to gray mine soils (407 cm3). Average pH of brown mine soils increased from 4.7 to 5.0, while gray mine soils declined from 7.9 to 7.0. Hydroseeding doubled tree volume index and ground cover on both mine soils. Hydroseeding doubled microbial biomass carbon (MBC) on brown mine soils (8.7 vs. 17.5 mg kg-1), but showed no effect on gray (13.3 vs. 12.8 mg kg-1). Hydroseeding also increased the ratio of MBC to soil organic C in both soils and more than tripled the ratio for potentially mineralizable nitrogen (PMN) to total N. Brown mine soils were a better growth medium than gray mine soils and hydroseeding was an important component of reclamation due to improved biochemical properties and microbial activity in mine soils.

  6. Incorporating hydraulic/hydromorphologic properties and their stage dependency into hydrologic compartmental models

    NASA Astrophysics Data System (ADS)

    Gustafsson, A.; Wörman, A.

    2009-04-01

    According to recent studies, the volumetric error of the predicted size of the spring flood in Sweden can be as large as 20%. A significant part of this error originates from simplifications in the spatial and hydrodynamic description of watercourse networks, as well as statistical problems to give proper weight to extreme flows. Possible ways to improve current hydrological modelling practises is by making models more adapted to varying flow conditions as well as by increasing the coupling between model parameters and physical catchment characteristics. This study formulates a methodology based in hydrodynamical/hydraulic theory to investigate how river network characteristics vary with flow stage and how to transfer this information to compartmental hydrologic models such as the HBV/HYPE models. This is particularly important during extreme flows when a significant portion of the water flows outside the normal stream channels. The aim is to combine knowledge about the hydrodynamics and hydro-morphology of watercourse networks to improve the predictions of peak flows. HYPE is a semi-distributed conceptual compartmental hydrological model which is currently being developed at the SMHI as a successor to the HBV model. The model (HYPE) is thought to be better adapted to varying flow conditions by using the dynamical response functions derived by the methodology described here. The distribution of residence times within the watercourse network - and how these depend on flow stage is analysed. This information is then incorporated into the response functions of the HYPE model, i.e. the compartmental model receives a dynamic transformation function relating river discharge to storativity within the sub-catchment. This response function hence reflects the topologic and hydromorphologic characteristics of the watercourse network as well as flow stage. Seven subcatchments in Rönne River basin (1900 km2) are studied to show how this approach can improve the prediction of peak flows. For the watercourse network analysis, two types of 1-D distributed network models are set up. One model contains a simplified hydraulic analysis of the watercourse network and how its properties vary with flow stage; the other network model is a numerical (stationary) routing routine. In the simplified hydraulic model, the effect of changed cross-sectional geometries is analysed. The focus is put on extreme flows with flooded cross-sections, where the hydromorphological properties of the network are changed considerably. By usage of the Manning equation, residence times are calculated for different flow stages. The second network model is used to numerically investigate the effects of the routing through each sub-catchment. Probability density functions of residence times are calculated for a range of flow stages to obtain subcatchment-specific information which incorporates the effects of flow stage and changed cross-sectional geometries. This information is thereafter used as response functions in the compartmental model which then will be more adapted to the effects of flooded cross-sections. Both network models are based on continuity principles regarding mass, energy and momentum. In both models, stationary flow conditions within the watercourse network are assumed, an assumption that might not be valid during extreme flows. In the simplified hydraulic model, the flow is assumed to be uniform between computational nodes - hence allowing the usage of the Manning equation for calculations of travelling times. The statements mentioned above are considered as possible sources of errors, however, more effort will be put into minimizing these effects, for example by finding optimal resolutions in space and time. The compartmental model and the network models are defined on a comparable form to facilitate the transfer of information between the models. Within the compartmental model, the streamflow component is separated from the remaining flows, since the network models only regard the attenuation in the stream channel. Parameters (derived from the si

  7. USING 3-D VISUAL COMPUTER SOFTWARE AND GRIDING ALGORITHM TO VIEW SEASONAL SOIL WATER CHANGES IN A HILLSHOPE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Conservation tillage and residue cover can reduce surface runoff. In hillslope soils, subsurface flow occurs when soil hydraulic properties meet the conditions for the formation of such flow. The objective of this study was to investigate soil hydraulic conductivity and water distribution in a hills...

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

    NASA Technical Reports Server (NTRS)

    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

    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.

  9. Crop Performance and Soil Properties in Two Artificially Eroded Soils in North-Central Alberta

    Microsoft Academic Search

    R. C. Izaurralde; S. S. Malhi; M. Nyborg; E. D. Solberg; M. C. Quiroga Jakas

    2006-01-01

    Field experiments were conducted from 1991 to 1995 at Josephburg (Orthic Black Chernozem, Typic Cryoboroll) and Cooking Lake (Orthic Gray Luvisol, Typic Cryoboralf), Alberta, to determine the impact of topsoil removal on selected soil properties, N-mineralization potential, and crop yield, and the effectiveness of various amendments for restoring the productivity of eroded soils. The simulated-erosion levels were established in the

  10. Trends in soil-vegetation dynamics in burned Mediterranean pine forests: the effects of soil properties

    Microsoft Academic Search

    L. Wittenberg; D. Malkinson

    2009-01-01

    Fire can impact a variety of soil physical and chemical properties. These changes may result, given the fire severity and the local conditions, in decreased infiltration and increased runoff and erosion rates. Most of these changes are caused by complex interactions among eco-geomorphic processes which affect, in turn, the rehabilitation dynamics of the soil and the regeneration of the burnt

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

    USGS Publications Warehouse

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

    1996-01-01

    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.

  12. PHYSIOLOGICAL ECOLOGY -ORIGINAL PAPER The effect of hydraulic lift on organic matter decomposition, soil

    E-print Network

    Jackson, Robert B.

    , soil nitrogen cycling, and nitrogen acquisition by a grass species Cristina Armas · John H. Kim understanding of where, when, and Communicated by Jim Ehleringer. C. Armas and J. H. Kim contributed equally-011-2065-2) contains supplementary material, which is available to authorized users. C. Armas Á J. H. Kim Á R. B

  13. Conservation tillage improves soil physical properties on different landscape positions of a coastal plain soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Improved crop management is necessary due to raising production costs and environmental concerns. Input optimization from precision crop management might provide some solutions to these issues. Spatial variability of soil physical properties can significantly affect the implementation of precision...

  14. Hydraulic responses to extreme drought conditions in three co-dominant tree species in shallow soil over bedrock.

    PubMed

    Kukowski, Kelly R; Schwinning, Susanne; Schwartz, Benjamin F

    2013-04-01

    An important component of the hydrological niche involves the partitioning of water sources, but in landscapes characterized by shallow soils over fractured bedrock, root growth is highly constrained. We conducted a study to determine how physical constraints in the root zone affected the water use of three tree species that commonly coexist on the Edwards Plateau of central Texas; cedar elm (Ulmus crassifolia), live oak (Quercus fusiformis), and Ashe juniper (Juniperus ashei). The year of the study was unusually dry; minimum predawn water potentials measured in August were -8 MPa in juniper, less than -8 MPa in elm, and -5 MPa in oak. All year long, species used nearly identical water sources, based on stable isotope analysis of stem water. Sap flow velocities began to decline simultaneously in May, but the rate of decline was fastest for oak and slowest for juniper. Thus, species partitioned water by time when they could not partition water by source. Juniper lost 15-30 % of its stem hydraulic conductivity, while percent loss for oak was 70-75 %, and 90 % for elm. There was no tree mortality in the year of the study, but 2 years later, after an even more severe drought in 2011, we recorded 34, 14, 6, and 1 % mortality among oak, elm, juniper, and Texas persimmon (Diospyros texana), respectively. Among the study species, mortality rates ranked in the same order as the rate of sap flow decline in 2009. Among the angiosperms, mortality rates correlated with wood density, lending further support to the hypothesis that species with more cavitation-resistant xylem are more susceptible to catastrophic hydraulic failure under acute drought. PMID:23053227

  15. Physical properties of tropical sandy soils: A large range of behaviours A. Bruand1)

    E-print Network

    Paris-Sud XI, Université de

    Physical properties of tropical sandy soils: A large range of behaviours A. Bruand1) , C. Hartmann2 properties, compaction Abstract Sandy soils are often considered as soils with physical properties grains are also responsible for variations in physical properties of tropical sandy soils. Under tropical

  16. Dielectric properties of soils as a function of moisture content

    NASA Technical Reports Server (NTRS)

    Cihlar, J.; Ulaby, F. T.

    1974-01-01

    Soil dielectric constant measurements are reviewed and the dependence of the dielectric constant on various soil parameters is determined. Moisture content is given special attention because of its practical significance in remote sensing and because it represents the single most influential parameter as far as soil dielectric properties are concerned. Relative complex dielectric constant curves are derived as a function of volumetric soil water content at three frequencies (1.3 GHz, 4.0 GHz, and 10.0 GHz) for each of three soil textures (sand, loam, and clay). These curves, presented in both tabular and graphical form, were chosen as representative of the reported experimental data. Calculations based on these curves showed that the power reflection coefficient and emissivity, unlike skin depth, vary only slightly as a function of frequency and soil texture.

  17. The influence of fluid properties on the success of hydraulic fracturing operations

    SciTech Connect

    Power, D.J.; Boger, D.V. [Univ. of Melbourne, Victoria (Australia); Paterson, L.

    1994-12-31

    Hydroxypropylguar based fluids are the most commonly used fluids for hydraulic fracturing. Through the addition of borate ions the polymer present in the fluid can crosslink to form a high viscosity gel. Prior to placement in the fracture the fluid is required to have a low viscosity to minimize friction losses in the tubular goods. A high viscosity fluid is required in the fracture for several reasons, primarily to suspend the proppant and to minimize fluid loss into the formation. This paper describes a new method which can be used to model the gelation reaction of crosslinking fluids. By modeling the dynamic properties of the fluid it is possible to predict the physical state of the fluid at any time during a fracturing treatment. Small amplitude oscillatory measurements are applied to fluid samples in a cone-and-plate geometry. The change in the dynamic properties with time can be fitted to a simple model which can then be used to determine the gel time for the fluid. Methods used to distinguish between the liquid and gel state are also discussed.

  18. Soil fracturing cracks soil remediation barriers

    SciTech Connect

    Baker, E. (Golder Applied Technologies Inc., Atlanta, GA (United States)); Leach, B. (Golder Associates, Calgary, Alberta (Canada). Hydraulic Fracturing Group)

    1995-03-01

    Remediating contaminants from clays, silts and other low-permeability soils always has been a challenge for environmental specialists. Such soils pose a paradox for cleanup professionals: although the soils' inherent low permeability greatly limits the rate and extent of contaminant movement, this characteristic also makes them especially difficult to remediate. Groundwater extraction and treatment, as well as soil-vapor extraction systems, are ineffective on low-permeability soils, even after years of operation. One technology alternative some remediation specialists are investigating is hydraulic fracturing. The first step in any soil fracturing operation to enhance remediation is characterizing the nature and extent of contamination, as well as the soil's geotechnical properties. Hydraulic fracturing essentially is a controlled failure of the soil mass, which is governed by existing stresses on the soil, the soil's strength or cohesion, and the nature of its discontinuities or structure. The design of soil fracturing programs also must consider the remediation method intended for a site. Soil fracturing alone is only an enabling technology to enhance the movement of fluids into and out of a soil mass. Contamination of the unsaturated zone with volatile organic compounds commonly is remediated using soil-vapor extraction with enhanced microbial degradation of the contaminants. Groundwater contamination may require extraction and treatment. In such applications, the fracturing program is designed to provide interconnections between natural discontinuities in the soil mass, as these are the channels along which water and contaminants travel.

  19. Determining the Porosity and Saturated Hydraulic Conductivity of Binary Mixtures

    SciTech Connect

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

    2009-09-27

    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.

  20. Analysis of Soil Water Retention Data Using Artificial Neural Networks

    Microsoft Academic Search

    Sharad K. Jain; Vijay P. Singh

    2004-01-01

    Many studies of water flow and solute transport in the vadose zone require estimates of the unsaturated soil hydraulic properties, including the soil water retention curve ~WRC! describing the relationship between soil suction and water content. An artificial neural network ~ANN! approach was developed to describe the WRC using observed data from several soils. The ANN approach was found to

  1. Soil property maps of Africa at 250 m resolution

    NASA Astrophysics Data System (ADS)

    Kempen, Bas; Hengl, Tomislav; Heuvelink, Gerard B. M.; Leenaars, Johan G. B.; Walsh, Markus G.; MacMillan, Robert A.; Mendes de Jesus, Jorge S.; Shepherd, Keith; Sila, Andrew; Desta, Lulseged T.; Tondoh, Jérôme E.

    2015-04-01

    Vast areas of arable land in sub-Saharan Africa suffer from low soil fertility and physical soil constraints, and significant amounts of nutrients are lost yearly due to unsustainable soil management practices. At the same time it is expected that agriculture in Africa must intensify to meet the growing demand for food and fiber the next decades. Protection and sustainable management of Africa's soil resources is crucial to achieve this. In this context, comprehensive, accurate and up-to-date soil information is an essential input to any agricultural or environmental management or policy and decision-making model. In Africa, detailed soil information has been fragmented and limited to specific zones of interest for decades. To help bridge the soil information gap in Africa, the Africa Soil Information Service (AfSIS) project was established in 2008. AfSIS builds on recent advances in digital soil mapping, infrared spectroscopy, remote sensing, (geo)statistics, and integrated soil fertility management to improve the way soils are evaluated, mapped, and monitored. Over the period 2008-2014, the AfSIS project has compiled two soil profile data sets (about 28,000 unique locations): the Africa Soil Profiles (legacy) database and the AfSIS Sentinel Site (new soil samples) database -- the two data sets represent the most comprehensive soil sample database of the African continent to date. In addition a large set of high-resolution environmental data layers (covariates) was assembled. The point data were used in the AfSIS project to generate a set of maps of key soil properties for the African continent at 250 m spatial resolution: sand, silt and clay fractions, bulk density, organic carbon, total nitrogen, pH, cation-exchange capacity, exchangeable bases (Ca, K, Mg, Na), exchangeable acidity, and Al content. These properties were mapped for six depth intervals up to 2 m: 0-5 cm, 5-15 cm, 15-30 cm, 30-60 cm, 60-100 cm, and 100-200 cm. Random forests modelling was used to relate the soil profile observations to a set covariates, that included global soil class and property maps, MODIS imagery and a DEM, in a 3D mapping framework. The model residuals were interpolated by 3D kriging, after which the kriging predictions were added to the random forests predictions to obtain the soil property predictions. The model predictions were validated with 5-fold cross-validation. The random forests models explained between 37% (exch. Na) and 85% (Al content) of the variation in the data. Results also show that globally predicted soil classes help improve continental scale mapping of the soil nutrients and are often among the most important predictors. We conclude that the first mapping results look promising. We used an automated modelling framework that enables re-computing the maps as new data becomes arrives, hereby gradually improving the maps. We showed that global maps of soil classes and properties produced with models that were predominantly calibrated on areas with plentiful observations can be used to improve the accuracy of predictions in regions with less plentiful data, such as Africa.

  2. Physically based closed-form expression for the bimodal unsaturated hydraulic conductivity function.

    PubMed

    Liu, Shiyu; Yasufuku, Noriyuki; Liu, Qiang; Hemanta, Hazarika

    2013-01-01

    Simulation of flow and contaminant transport through the vadose zone requires accurate parameterization of the soil hydraulic properties. This requirement is particularly important for soils with a complex structure. In the present study, a physically based closed-form expression for the bimodal unsaturated hydraulic conductivity function is proposed for soils with bimodal pore-size distribution. It combines the bimodal representation of the soil-water characteristic curve (SWCC) function of Liu with the conductivity representation model of Mualem. The proposed equations are defined by parameters that have physical significance, which can be related to the properties of the materials. Experimental data for the representation of bimodal SWCCs and corresponding hydraulic conductivity curves were used to demonstrate the applicability of the proposed functions. The proposed approaches resulted in good agreement with experimental data. These functions can potentially be used as an effective tool for identifying hydraulic porosities in mediums with a complex structure. PMID:23863424

  3. The effects of spatially-varying soil properties on soil erosion

    SciTech Connect

    Springer, E.P.; Cundy, T.W.

    1988-01-01

    The objective of this study is to investigate the effects of only rainfall excess generation on erosion. We illustrate the effects of spatial variation in saturated hydraulic conductivity (K/sub s/) on the spatial and temporal distributions of erosion resulting from overland flow. We use this as a basis to demonstrate the potential for bias in parameters estimated from field data. Mathematical modeling of soil erosion must include surface runoff the dominant transport mechanism. Rainfall excess when routed over the surface, produces a distribution of velocities and depths in response to surface, roughness, surface form or microtopography, and available water. The spatial distribution of velocities and depths strongly affects sediment delivery as well as the re-distribution of soil on the hillslope. 23 refs., 12 figs., 3 tabs.

  4. Electrokinetic retention, migration and remediation of nitrates in silty loam soil under hydraulic gradients

    Microsoft Academic Search

    Krishnapillai Manokararajah; Ramanathan Sri Ranjan

    2005-01-01

    Contamination of groundwater by nitrates leaching from intensive agricultural and livestock operations have become a major concern for surrounding communities that use groundwater as their water supply. High levels of nitrate in drinking water poses a significant risk to human health, i.e., methaemoglobinaemia (“blue baby” syndrome).The traditional pump-and-treat method is ineffective in medium to fine-textured agricultural soils due to the

  5. Hydraulic properties of Zinnia elegans : from cellular development in vitro to performance in planta

    Microsoft Academic Search

    P. Twumasi

    2007-01-01

    The water status in plants is dependent on the xylem hydraulic conductance. In cut flowers, for example, the preservation of continuous hydraulic conductance is important for maintaining longer vase life, an important index for cut flower quality. Many factors, such as stomata performance, root water uptake efficiency, temperature, light quality and humidity, influence the efficiency of water transport in the

  6. Unraveling the size distributions of surface properties for purple soil and yellow soil.

    PubMed

    Tang, Ying; Li, Hang; Liu, Xinmin; Zhu, Hualing; Tian, Rui

    2015-06-01

    Soils contain diverse colloidal particles whose properties are pertinent to ecological and human health, whereas few investigations systematically analyze the surface properties of these particles. The objective of this study was to elucidate the surface properties of particles within targeted size ranges (i.e. >10, 1-10, 0.5-1, 0.2-0.5 and <0.2?m) for a purple soil (Entisol) and a yellow soil (Ultisol) using the combined determination method. The mineralogy of corresponding particle-size fractions was determined by X-ray diffraction. We found that up to 80% of the specific surface area and 85% of the surface charge of the entire soil came from colloidal-sized particles (<1?m), and almost half of the specific surface area and surface charge came from the smallest particles (<0.2?m). Vermiculite, illite, montmorillonite and mica dominated in the colloidal-sized particles, of which the smallest particles had the highest proportion of vermiculite and montmorillonite. For a given size fraction, the purple soil had a larger specific surface area, stronger electrostatic field, and higher surface charge than the yellow soil due to differences in mineralogy. Likewise, the differences in surface properties among the various particle-size fractions can also be ascribed to mineralogy. Our results indicated that soil surface properties were essentially determined by the colloidal-sized particles, and the <0.2?m nanoparticles made the largest contribution to soil properties. The composition of clay minerals within the diverse particle-size fractions could fully explain the size distributions of surface properties. PMID:26040734

  7. The use of soil mechanical properties to evidence the effect of cultivation practives on soil structure

    NASA Astrophysics Data System (ADS)

    Chaplain, V.; Défossez, P.; Delarue, G.; Richard, G.; Roger-Estrade, J.; Tessier, D.

    2009-04-01

    The use of soil mechanical properties to evidence the effect of cultivation practices on soil structure Véronique Chaplain1, Pauline Défossez2, Gislaine Delarue1, Guy Richard3, Jean Roger-Estrade4 and Daniel Tessier1 1 UR INRA PESSAC RD 10 F-78026 Versailles cedex 2 UMR INRA/URCA FARE, 2 Esplanade Roland Garros, BP 224 F-51686 Reims cedex 2 3 UR INRA Sols 2163 Avenue de la Pomme de Pin - CS 40001 ARDON F-45075 Orléans Cedex 2 4 AgroParisTech, département SIAFEE - BP 01 F-78850 Thiverval-Grignon Corresponding author : chaplain@versailles.inra.fr In this study, we proposed to use mechanical properties of soils deduced from compression curves as characteristics of soil structure to trap the effects of cultivation practices, especially in alternative tillage systems. Mechanical parameters studied were the pre-compression?stress and the compression index Cc classically related to physical properties of soils such as texture, water content and bulk density. All compression curves were performed at pF 2.5. In the loamy soils, sampled in two locations of the French Parisian basin, this value corresponds to water content at which compaction risk is maximum. We systematically compared the mechanical behaviour of remoulded and undisturbed soils samples. On both sites cultivation practices did not change the linear relationship of Cc with the initial void ratio. Thus this parameter can be used to predict the intrinsic sensitivity of soil to compaction. On the contrary, the relationship observed between the pre-compression pressure and the initial void ratio on remoulded samples disappeared and no correlation was observed in both situations. This result suggests that for a given soil, pre-compression pressure is sensitive to the initial soil structure of the undisturbed samples and therefore can be used as an indicator of the effects of cultivation practices on soil structure.

  8. Effects of aggressive remediation on soil properties and function

    NASA Astrophysics Data System (ADS)

    Switzer, Christine; Zihms, Stephanie; Pape, Andrew; Robson, Andrew; Knapp, Charles

    2013-04-01

    Aggressive remediation processes such as thermal desorption, smouldering, and chemical oxidiation remediation processes have significant promise to deliver substantial contaminant reduction in short periods of time, effecting as much as 95-99+% mass removal from non-aqueous phase liquid (NAPL) source zones. In situ thermal remediation exposes soils to temperatures of 100+°C for periods of weeks or months. In situ smouldering exposes soils to 600-1000+°C for hours to days. Chemical oxidation exposes soils to harsh oxidizing chemicals for weeks or months effecting reactive degradation of chemical contaminants but also surrounding soils. These processes have the potential to result in significant changes to the soil properties, particularly at the particle surface and grain interfaces. The dynamic effects of these changes have important implications in soil management practice. The mobilisation of soil nutrients may challenge rehabilitation or biological "polishing" after aggressive remediation. Plant germination and growth are inhibited and water dynamics are affected as well. Although permeability remains unaffected, infiltration is more rapid and capillary rise is reduced after smouldering remediation. Mobilisation of fines does not explain the change in infiltration and capillary rise; these effects persist after removal of the smaller half of the particle size distribution. Some separation of the soil column is observed in water infiltration after both thermal and smouldering remediation, indicating that erosion and subsidence are potential problems. These effects may be manifestations of subcritical water repellency. Based on the retention of capillary rise and lack of effects on other soil properties, the soil should be amenable to improvement measures. This presentation will place the effects of aggressive remediation into context within real soils and model materials.

  9. Improving root-zone soil properties for Trembling Aspen in a reconstructed mine-site soil

    NASA Astrophysics Data System (ADS)

    Dyck, M. F.; Sabbagh, P.; Bockstette, S.; Landhäusser, S.; Pinno, B.

    2014-12-01

    Surface mining activities have significantly depleted natural tree cover, especially trembling aspen (Populus tremuloides), in the Boreal Forest and Aspen Parkland Natural Regions of Alberta. The natural soil profile is usually destroyed during these mining activities and soil and landscape reconstruction is typically the first step in the reclamation process. However, the mine tailings and overburden materials used for these new soils often become compacted during the reconstruction process because they are subjected to high amounts of traffic with heavy equipment. Compacted soils generally have low porosity and low penetrability through increased soil strength, making it difficult for roots to elongate and explore the soil. Compaction also reduces infiltration capacity and drainage, which can cause excessive runoff and soil erosion. To improve the pore size distribution and water transmission, subsoil ripping was carried out in a test plot at Genesee Prairie Mine, Alberta. Within the site, six replicates with two treatments each, unripped (compacted) and ripped (decompacted), were established with 20-m buffers between them. The main objective of this research was to characterize the effects of subsoil ripping on soil physical properties and the longevity of those effects.as well as soil water dynamics during spring snowmelt. Results showed improved bulk density, pore size distribution and water infiltration in the soil as a result of the deep ripping, but these improvements appear to be temporary.

  10. Landscape level variation in soil resources and microbial properties in a no-till corn field

    Microsoft Academic Search

    M. A. Cavigelli; L. L. Lengnick; J. S. Buyer; D. Fravel; Z. Handoo; G. McCarty; P. Millner; L. Sikora; S. Wright; B. Vinyard; M. Rabenhorst

    2005-01-01

    Soil microbial properties are known to exhibit high spatial and temporal variability, which can hinder our understanding of the effects of agricultural management on soil microbial activities, populations and communities. However, if this variability is explicitly considered in soil sampling schemes, experimental results can help us better understand soil microbial properties. In this initial assessment of soil resources and microbial

  11. Multivariate 3D modelling of Scottish soil properties

    NASA Astrophysics Data System (ADS)

    Poggio, Laura; Gimona, Alessandro

    2015-04-01

    Information regarding soil properties across landscapes at national or continental scales is critical for better soil and environmental management and for climate regulation and adaptation policy. The prediction of soil properties variation in space and time and their uncertainty is an important part of environmental modelling. Soil properties, and in particular the 3 fractions of soil texture, exhibit strong co-variation among themselves and therefore taking into account this correlation leads to spatially more accurate results. In this study the continuous vertical and lateral distributions of relevant soil properties in Scottish soils were modelled with a multivariate 3D-GAM+GS approach. The approach used involves 1) modelling the multivariate trend with full 3D spatial correlation, i.e., exploiting the values of the neighbouring pixels in 3D-space, and 2) 3D kriging to interpolate the residuals. The values at each cell for each of the considered depth layers were defined using a hybrid GAM-geostatistical 3D model, combining the fitting of a GAM (generalised Additive Models) to estimate multivariate trend of the variables, using a 3D smoother with related covariates. Gaussian simulations of the model residuals were used as spatial component to account for local details. A dataset of about 26,000 horizons (7,800 profiles) was used for this study. A validation set was randomly selected as 25% of the full dataset. Numerous covariates derived from globally available data, such as MODIS and SRTM, are considered. The results of the 3D-GAM+kriging showed low RMSE values, good R squared and an accurate reproduction of the spatial structure of the data for a range of soil properties. The results have an out-of-sample RMSE between 10 to 15% of the observed range when taking into account the whole profile. The approach followed allows the assessment of the uncertainty of both the trend and the residuals.

  12. Thermal properties of soils: effect of biochar application

    NASA Astrophysics Data System (ADS)

    Usowicz, Boguslaw; Lukowski, Mateusz; Lipiec, Jerzy

    2014-05-01

    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.

  13. Some surface properties of Apollo 17 soils

    NASA Technical Reports Server (NTRS)

    Holmes, H. F.; Fuller, E. L., Jr.; Gammage, R. B.

    1974-01-01

    The surface chemistry of Apollo 17 lunar fines samples 74220 (the orange soil) and 74241 (the gray control soil) has been studied by measuring the adsorption of nitrogen, argon, and oxygen (all at -196 C) and also water vapor (at 20 C or 22 C). In agreement with results for samples from other missions, both samples had low initial specific surface areas, consisted of nonporous particles, and were attacked by water vapor at high relative pressures to give an increased specific surface area and create a pore system which gave rise to a capillary condensation hysteresis loop in the adsorption isotherms. In contrast to previous samples, both of the Apollo 17 soils were partially hydrophobic in their initial interaction with water vapor (both samples were completely hydrophilic after the reaction with water). The results are consistent with formation at high temperatures without subsequent exposure to significant amounts of water.

  14. The effect of hydraulic lift on organic matter decomposition, soil nitrogen cycling, and nitrogen acquisition by a grass species.

    PubMed

    Armas, Cristina; Kim, John H; Bleby, Timothy M; Jackson, Robert B

    2012-01-01

    Hydraulic lift (HL) is the passive movement of water through plant roots, driven by gradients in water potential. The greater soil-water availability resulting from HL may in principle lead to higher plant nutrient uptake, but the evidence for this hypothesis is not universally supported by current experiments. We grew a grass species common in North America in two-layer pots with three treatments: (1) the lower layer watered, the upper one unwatered (HL), (2) both layers watered (W), and (3) the lower layer watered, the upper one unwatered, but with continuous light 24 h a day to limit HL (no-HL). We inserted ingrowth cores filled with enriched-nitrogen organic matter ((15)N-OM) in the upper layer and tested whether decomposition, mineralization and uptake of (15)N were higher in plants performing HL than in plants without HL. Soils in the upper layer were significantly wetter in the HL treatment than in the no-HL treatment. Decomposition rates were similar in the W and HL treatments and lower in no-HL. On average, the concentration of NH(4)(+)-N in ingrowth cores was highest in the W treatment, and NO(3)(-)-N concentrations were highest in the no-HL treatment, with HL having intermediate values for both, suggesting differential mineralization of organic N among treatments. Aboveground biomass, leaf (15)N contents and the (15)N uptake in aboveground tissues were higher in W and HL than in no-HL, indicating higher nutrient uptake and improved N status of plants performing HL. However, there were no differences in total root nitrogen content or (15)N uptake by roots, indicating that HL affected plant allocation of acquired N to photosynthetic tissues. Our evidence for the role of HL in organic matter decomposition and nutrient cycling suggests that HL could have positive effects on plant nutrient dynamics and nutrient turnover. PMID:21766189

  15. Regional evaluation of hydraulic properties in variably fractured rock using a hydrostructural domain approach

    NASA Astrophysics Data System (ADS)

    Surrette, M.; Allen, D. M.; Journeay, M.

    2008-02-01

    A hydrostructural domain approach was tested and validated in fractured bedrock aquifers of the Gulf Islands, British Columbia (BC), Canada. Relative potential hydraulic properties for three hydrostructural domains in folded and faulted sedimentary rocks were derived using stochastically generated fracture data and hybrid discrete fracture network-equivalent porous media (DFN-EPM) modelling. Model-derived relative potential transmissivity values show good spatial agreement with transmissivity values obtained from pumping tests at selected sites. A spatial pattern of increasing transmissivity towards the southeast along the island chain is consistent between both datasets. Cluster analysis on relative potential permeability values obtained from a larger dataset for the region identified four clusters with geometric means of 9 × 10-13, 4 × 10-13, 2 × 10-13, and 3 × 10-14 m2. The general trend is an increase in relative potential permeability toward the southeast, emulating the trends identified in the site-specific analyses. Relative potential permeability values increase with proximity to the hinge line of a regional northwest-trending asymmetric fault propagation fold structure, and with proximity to superimposed high-angle north- and northeast-trending brittle faults. The results are consistent with documented patterns of structurally controlled fluid flow and show promise for use in regional characterization of fractured bedrock aquifers.

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

    E-print Network

    Speake, Robert Cary

    1986-01-01

    of a dye/tracer study. To properly construct a competent compacted soil liner requires the str1ct appl1cat1on of construct1on quality control, which includes proper so11 processing and construction techniques. ACKNOWLEDGEMENTS The author wishes... to express his gratitude to Dr. Wes James, Dr. Ralph Wurbs, and Dr. Pat Domenico for their review of the manuscript for this effort. Additional thanks are extended to Dr. James for his financial assistance dur1ng the author's first two semesters...

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

    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.

  18. Spatial variability of magnetic soil properties

    NASA Astrophysics Data System (ADS)

    van Dam, Remke L.; Hendrickx, Jan M.; Harrison, Bruce; Borchers, Brian; Norman, David I.; Ndur, Samuel; Jasper, Chris; Niemeyer, Patrick; Nartey, Robert; Vega, David N.; Calvo, Lucas; Simms, Janet E.

    2004-09-01

    The presence of magnetic iron oxides in the soil can seriously hamper the performance of electromagnetic sensors for the detection of buried land mines and unexploded ordnance (UXO). Previous work has shown that spatial variability in soil water content and texture affects the performance of ground penetrating radar and thermal sensors for land mine detection. In this paper we aim to study the spatial variability of iron oxides in tropical soils and the possible effect on electromagnetic induction sensors for buried low-metal land mine and UXO detection. We selected field sites in Panama, Hawaii, and Ghana. Along several horizontal transects in Panama and Hawaii we took closely spaced magnetic susceptibility readings using Bartington MS2D and MS2F sensors. In addition to the field measurements, we took soil samples from the selected sites for laboratory measurements of dual frequency magnetic susceptibility and textural characteristics of the material. The magnetic susceptibility values show a significant spatial variation in susceptibility and are comparable to values reported to hamper the operation of metal detectors in parts of Africa and Asia. The absolute values of susceptibility do not correlate with both frequency dependence and total iron content, which is an indication of the presence of different types of iron oxides in the studied material.

  19. Comparison of Soil Properties and Microbial Activities between Air-Dried and Rewetted Desert and Oasis Soils in Northwest China

    Microsoft Academic Search

    Chen-Hua Li; Yan Li; Li-Song Tang

    2011-01-01

    An air-drying and rewetting (AW) experiment was used to examine the responses of soil properties and microbial activities to abrupt alteration of water availability between desert and oasis soils in northwest China. The results revealed that AW increased soil pH and available nitrogen and phosphorus but decreased soil organic matter in the desert, while available phosphorus increased and available nitrogen

  20. Tillage-induced seasonal changes in soil physical properties affecting soil CO 2 evolution under intensive cropping

    Microsoft Academic Search

    A. J. Franzluebbers; F. M. Hons; D. A. Zuberer

    1995-01-01

    Crop management practices impact soil productivity by altering the soil environment, which in turn affects microbial growth and decomposition processes that transform plant-produced C to soil organic matter (SOM) or CO2. Reduced tillage increases SOM in the long term, but there is limited information on the in situ seasonal changes in soil physical and biological properties that affect SOM dynamics.

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

    E-print Network

    Ma, Lena

    1 EFFECTS OF COMPOST AND LIME APPLICATION ON SOIL CHEMICAL PROPERTIES, SOIL MICROBIAL COMMUNITY content and fertility, and can support the growth of soil-borne pathogens. Some growers choose to apply compost as an antagonistic suppression approach to combat soil-borne disease effects on crop yields

  2. Summary and evaluation of hydraulic property data available for Eielson Air Force Base, Alaska

    SciTech Connect

    Spane, F.A. Jr.; Thorne, P.D.

    1994-07-01

    Most of the contaminant source areas at Eielson Air Force Base are located above an unconfined alluvial aquifer with relatively high hydraulic conductivity. Hydraulic tests that have been conducted on wells at the base were evaluated, and in some cases reanalyzed, to determine hydraulic conductivity and specific yield for the aquifer. The reviewed tests included 2 multiple-well pumping tests and 30 slug tests. One slug test was conducted on a well in the bedrock aquifer at Site 38. All the other tests were conducted on the alluvial aquifer.

  3. Effects of soil electromagnetic properties on metal detectors

    Microsoft Academic Search

    Yogadhish Das

    2006-01-01

    This paper presents an analysis, based on existing work in geophysics and nondestructive testing, of the effects of soil electromagnetic properties on the functioning of metal detectors widely used to detect buried landmines. The host soil is modeled as a half-space having real and frequency-independent electrical conductivity but frequency-dependent complex magnetic susceptibility. The analysis technique has been applied to three

  4. Lantana camara L. (Verbenaceae) invasion effects on soil physicochemical properties

    Microsoft Academic Search

    Olusegun O. Osunkoya; Christine Perrett

    2011-01-01

    Lantana camara is a recognized weed of worldwide significance due to its extensive distribution and its impacts on primary industries and\\u000a nature conservation. However, quantitative data on the impact of the weed on soil ecosystem properties are scanty, especially\\u000a in SE Australia, despite the pervasive presence of the weed along its coastal and inland regions. Consequently, mineral soils\\u000a for physicochemical

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

    Microsoft Academic Search

    Rockhold; Mark L

    2008-01-01

    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

  6. Water resource partitioning, stem xylem hydraulic properties, and plant water use strategies in a seasonally dry riparian tropical rainforest.

    PubMed

    Drake, P L; Franks, P J

    2003-11-01

    This study investigated seasonal variation in the origin of water used by plants in a riparian tropical rainforest community and explored linkages between plant water source, plant xylem hydraulic conductivity and response to the onset of dry conditions. The study focused on five co-dominant canopy species, comprising three tree species ( Doryphora aromatica, Argyrodendron trifoliolatum, Castanospora alphandii) and two climbing palms ( Calamus australis and Calamus caryotoides). Stable isotope ratios of oxygen in water (delta(18)O) from soil, groundwater, stream water and plant xylem measured in the wet season and the subsequent dry season revealed water resource partitioning between species in the dry season. Measurement of stem-area-specific hydraulic conductivity ( K(S)) in the wet season and subsequent dry season showed a significant dry-season loss of K(S) in three of the five species ( Castanospora alphandii, Calamus australis and C. caryotoides) and a decrease in mean K(S) for all species. This loss of hydraulic conductivity was positively correlated with the difference between wet-season and dry-season midday leaf water potentials and with leaf carbon isotope discrimination, indicating that plants that were less susceptible to loss of conductivity had greater control over transpiration rate and were more water-use efficient. PMID:12883990

  7. Changes in the properties of soils in a solonetz soil complex thirty years after reclamation

    NASA Astrophysics Data System (ADS)

    Kalinichenko, V. P.; Sharshak, V. K.; Mironchenko, S. F.; Chernenko, V. V.; Ladan, E. P.; Genev, E. D.; Illarionov, V. V.; Udalov, A. V.; Udalov, V. V.; Kippel, E. V.

    2014-04-01

    The long-term (30 year) dynamics of a solonetz soil complex composed of solonetzic light chestnut soils and chestnut solonetzes under standard conditions and with the application of agromeliorative measures are considered. When the standard zonal agricultural practice is used, the soils of the solonetzic complex have unfavorable agrophysical, chemical, and physicochemical properties and low productivity. After 30 years of the standard three-level tillage of the soils to a depth of 40-45 cm, the productivity of the biogeocenosis decreased. Thirty years after a single rotary-milling subsoil treatment of the 20- to 45-cm soil layer using a milling tool FS-1.3, there were no morphological features pointing to the restoration of the solonetzic process. The humus content in the 0-to 20-cm and 20-to 40-cm soil layers was 2.3 and 1.7%, respectively; the content of adsorbed Na+ in the 20-to 30-cm layer was 11.6% of the total exchange capacity, or 38% lower than its content in the reference soil. The additional yield reached 30-70% and more of that obtained with the standard agricultural technology used during the whole period under investigation. The method of systems biogeotechnology (systems bio-geo engineering) is proposed as a method for the preventive control of soil evolution and the maintenance of the stability and high productivity of the soil cover.

  8. Unsaturated conductivity and diffusivity of selected Texas soils in relation to their physical and chemical properties 

    E-print Network

    Derendinger, George Lewis

    1968-01-01

    conductivity of soils in an unsaturated condition. 7. A high sodium content in soils is assoc' abed with a decreased diffusivity. B. The inclination and form of the diffusivity curves in relation to the volumetric water content of soils gives... flow rate per sample volume, cm~/cm direction coordinates volumetr ' c water content, cm~/cm-i fluid dens" ty, gm/cm3 hydraulic head, cm ix LIST OF MINERALOGICAL COMPOSITION SYMBOLS ~Smb o 1 Definition Upon K saturation the amorphous...

  9. Comparison of nifH Gene Pools in Soils and Soil Microenvironments with Contrasting Properties

    PubMed Central

    Poly, Franck; Ranjard, Lionel; Nazaret, Sylvie; Gourbière, François; Monrozier, Lucile Jocteur

    2001-01-01

    The similarities and differences in the structures of the nifH gene pools of six different soils (Montrond, LCSA-p, Vernon, Dombes, LCSA-c, and Thysse Kaymor) and five soil fractions extracted from LCSA-c were studied. Bacterial DNA was directly extracted from the soils, and a region of the nifH gene was amplified by PCR and analyzed by restriction. Soils were selected on the basis of differences in soil management, plant cover, and major physicochemical properties. Microenvironments differed on the basis of the sizes of the constituent particles and the organic carbon and clay contents. Restriction profiles were subjected to principal-component analysis. We showed that the composition of the diazotrophic communities varied both on a large scale (among soils) and on a microscale (among microenvironments in LCSA-c soil). Soil management seemed to be the major parameter influencing differences in the nifH gene pool structure among soils by controlling inorganic nitrogen content and its variation. However, physicochemical parameters (texture and total C and N contents) were found to correlate with differences among nifH gene pools on a microscale. We hypothesize that the observed nifH genetic structures resulted from the adaptation to fluctuating conditions (cultivated soil, forest soil, coarse fractions) or constant conditions (permanent pasture soil, fine fractions). We attempted to identify a specific band within the profile of the clay fraction by cloning and sequencing it and comparing it with the gene databases. Unexpectedly, the nifH sequences of the dominant bacteria were most similar to sequences of unidentified marine eubacteria. PMID:11319109

  10. Effects of Single Chinese Fir and Mixed Leaf Litters on Soil Chemical, Microbial Properties and Soil Enzyme Activities

    Microsoft Academic Search

    Y. L. Hu; S. L. Wang; D. H. Zeng

    2006-01-01

    The quality of leaf litter can control decomposition processes and affect the nutrient availability for plant uptake. In this\\u000a study, we investigated the effect of single leaf litter (Chinese fir – Cunninghamia lamcealata (Lamb.) Hook) and mixed leaf litters (C. lamcealata, Liquidamba formosana Hance and Alnus cremastogyne Burk) on soil chemical properties, soil microbial properties and soil enzyme activities during

  11. Methods for prediction of soil dielectric properties: a review

    NASA Astrophysics Data System (ADS)

    van Dam, Remke L.; Borchers, Brian; Hendrickx, Jan M. H.

    2005-06-01

    Electromagnetic sensors such as ground penetrating radar and electromagnetic induction sensors are among the most widely used methods for the detection of buried land mines and unexploded ordnance. However, the performance of these sensors depends on the dielectric properties of the soil, which in turn are related to soil properties such as texture, bulk density, and water content. To predict the performance of electromagnetic sensors it is common to estimate the soil dielectric properties using models. However, the wide variety of available models, each with its own characteristics, makes it difficult to select the appropriate one for each occasion. In this paper we present an overview of the available methods, ranging from phenomenological Cole-Cole and Debye models to volume-based dielectric mixing models, and (semi-) empirical pedotransfer functions.

  12. General Relationships between Abiotic Soil Properties and Soil Biota across Spatial Scales and Different Land-Use Types

    PubMed Central

    Birkhofer, Klaus; Schöning, Ingo; Alt, Fabian; Herold, Nadine; Klarner, Bernhard; Maraun, Mark; Marhan, Sven; Oelmann, Yvonne; Wubet, Tesfaye; Yurkov, Andrey; Begerow, Dominik; Berner, Doreen; Buscot, François; Daniel, Rolf; Diekötter, Tim; Ehnes, Roswitha B.; Erdmann, Georgia; Fischer, Christiane; Foesel, Bärbel; Groh, Janine; Gutknecht, Jessica; Kandeler, Ellen; Lang, Christa; Lohaus, Gertrud; Meyer, Annabel; Nacke, Heiko; Näther, Astrid; Overmann, Jörg; Polle, Andrea; Pollierer, Melanie M.; Scheu, Stefan; Schloter, Michael; Schulze, Ernst-Detlef; Schulze, Waltraud; Weinert, Jan; Weisser, Wolfgang W.; Wolters, Volkmar; Schrumpf, Marion

    2012-01-01

    Very few principles have been unraveled that explain the relationship between soil properties and soil biota across large spatial scales and different land-use types. Here, we seek these general relationships using data from 52 differently managed grassland and forest soils in three study regions spanning a latitudinal gradient in Germany. We hypothesize that, after extraction of variation that is explained by location and land-use type, soil properties still explain significant proportions of variation in the abundance and diversity of soil biota. If the relationships between predictors and soil organisms were analyzed individually for each predictor group, soil properties explained the highest amount of variation in soil biota abundance and diversity, followed by land-use type and sampling location. After extraction of variation that originated from location or land-use, abiotic soil properties explained significant amounts of variation in fungal, meso- and macrofauna, but not in yeast or bacterial biomass or diversity. Nitrate or nitrogen concentration and fungal biomass were positively related, but nitrate concentration was negatively related to the abundances of Collembola and mites and to the myriapod species richness across a range of forest and grassland soils. The species richness of earthworms was positively correlated with clay content of soils independent of sample location and land-use type. Our study indicates that after accounting for heterogeneity resulting from large scale differences among sampling locations and land-use types, soil properties still explain significant proportions of variation in fungal and soil fauna abundance or diversity. However, soil biota was also related to processes that act at larger spatial scales and bacteria or soil yeasts only showed weak relationships to soil properties. We therefore argue that more general relationships between soil properties and soil biota can only be derived from future studies that consider larger spatial scales and different land-use types. PMID:22937029

  13. Soil properties affected by combinations of soil solarization and organic amendment

    Microsoft Academic Search

    Komariah; Kengo Ito; Takeo Onishi; Masateru Senge

    2011-01-01

    A field experiment was conducted to investigate the effects on soil properties of solarization combined with rice bran additive.\\u000a The treatments included control (bare soil), black polyethylene film mulch (BM), clear polyethylene film mulch (CM), rice\\u000a bran mixture (RBMx), rice bran mulch (RBM), rice bran mixture and black polyethylene film mulch (RBMx + BM), rice bran and\\u000a black polyethylene film mulch (RBM + BM),

  14. Hygrothermal Material Properties for Soils in Building Science

    SciTech Connect

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

    2013-01-01

    Saving energy in buildings is top of mind with today s building professionals. Although designing energy-efficient walls and roofs is mostly a no-brainer, ensuring that below-grade foundations do not generate moisture problems has become even more complex, particularly because of how soil is involved. Hygrothermal performance of soils coupled to buildings is complicated because of the dearth of information on soil properties. A computational approach for heat transfer through the ground has been well-defined, and simplified methods have been developed. These approaches, however, generally ignore the transfer of soil moisture, which is not negligible. The intention of an ongoing study at Oak Ridge (TN) National Laboratory, therefore, is to gather, comprehend and adapt soil properties from soil science as well. The obtained information must be applicable to related tasks in building science and validated with hygrothermal calculation tools, where additional plugins to the existing software code WUFI (an acronym for Warme unde Felichte Instructionar, which translates to unsteady heat and moisture) are required. (See the sidebar, opposite page, for specifics on WUFI.)Simulation results from WUFI are being compared with existing thermal-only measurements and are being accomplished with ongoing hygrothermal measurements. The final outcome of the study will be the evaluation of several soil types in several climate zones for a number of basement assembly types. The study will define the type of soil, together with the type of building construction considered most and least reliable with respect to energy consumption and moisture safety. Furthermore, the study will determine the influences that different soils have on total energy loss through the ground.

  15. Methanotroph community properties determine the sensitivity of soil methane oxidation to variation in soil moisture

    NASA Astrophysics Data System (ADS)

    von Fischer, J.

    2005-12-01

    Soil biogeochemical processes depend on aspects of physical and biological structure that are very fragile. This fragile nature has limited our ability to understand the relative importance of abiotic vs. biotic controls on biogeochemical processes. To overcome this limitation, I have applied a non-disruptive, in-situ method for studying the controls of a relatively simple biogeochemical process: methane consumption in upland soils. My work uses additions of an inert tracer gas (sulfur hexafluoride, SF6) to the headspace of gas flux chambers that are coincident with methane flux measures. By measuring both methane flux and SF6 transport at the same time, I simultaneously and uniquely measure the physical transport and biological transformations that collectively regulate methane flux on the Shortgrass Steppe LTER (SGS LTER) site in north central Colorado, USA. Study areas on the SGS LTER differed in soil texture and vegetation, but none had been tilled. My results reveal that the response of methane flux to changes in soil moisture differed among study areas such that some showed steep declines with increasing soil water content while other sites had minimal changes. Underlying this response, my data show that the methane uptake capacity, a property of the methanotroph community, is greatest in soils that show the least sensitivity to soil moisture. Using a methane reaction-diffusion model, I have constrained the potential importance of methanotroph population size, spatial distribution and enzymatic properties for structuring the observed differences in methane uptake capacity.

  16. Effects of olive mill wastes added to olive grove soils on erosion and soil properties

    NASA Astrophysics Data System (ADS)

    Lozano-García, Beatriz; Parras-Alcántara, Luis

    2014-05-01

    INTRODUCTION The increasing degradation of olive groves by effect of organic matter losses derived from intensive agricultural practices has promoted the use (by olive farmers) of olive mill wastes (olive leaves and alperujo) which contain large amounts of organic matter and are free of heavy metals and pathogenic microorganisms. In this work we compared the effects of these oil mill wastes on the decrease of soil erosion, also, we undertook the assessment of the organic carbon and nitrogen contents of soil, their distribution across the profile, the accumulation and Stratification ratios (SRs) of soil organic carbon (SOC) and total nitrogen (TN), and the C:N ratio, in Cambisols in Mediterranean olive groves treated with olive leaves and alperujo. MATERIALS AND METHODS The study area was a typical olive grove in southern Spain under conventional tillage (CT). Three plots were established. The first one was the control plot; the second one was treated with olive leaves (CTol) and the third one, with alperujo (CTa). 9 samples per plot were collected to examine the response of the soil 3 years after application of the wastes. Soil properties determined were: soil particle size, pH, bulk density, the available water capacity, SOC, TN and C:N ratio. SOC and N stock, expressed for a specific depth in Mg ha-1. Stratification ratios (SRs) (that can be used as an indicator of dynamic soil quality) for SOC and TN at three different depths were calculated. The erosion study was based on simulations of rain; that have been carried out in order to highlight differences in the phenomena of runoff and soil losses in the three plots considered. The effect of different treatments on soil properties was analyzed using a ANOVA, followed by an Anderson-Darling test. RESULTS Supplying the soil with the wastes significantly improved physical and chemical properties in the studied soils with respect to the control. C and N stocks increased, the SOC stock was 75.4 Mg ha-1 in CT, 91.5 Mg ha-1 in CTa and 136.3 Mg ha-1 in CTol; and the TN stock 12.1, 13.9 and 16.1 Mg ha-1 in CT, CTa and CTol, respectively. In addition, both oil mill wastes contributed to delay runoff generation and erosion, enhancing the infiltration of rainwater. Furthermore, application of the wastes improved soil quality (SRs of SOC were greater than 2). So the addition of these oil mill wastes to agricultural soils has become a viable solution to their disposal; not only do they enrich deficient soils with organic matter, but also improve their physical and chemical properties, even decrease soil erosion, especially olive leaves. REFERENCES Lozano-García, B., Parras-Alcántara, L., del Toro, M., 2011. The effects of agricultural management with oil mill by-products on surface soil properties, runoff and soil losses in southern Spain. Catena 85, 187-193. Lozano-García, B., Parras-Alcántara, L., 2013. Short-term effects of olive mill by-products on soil organic carbon, total N, C:N ratio and stratification ratios in a Mediterranean olive grove. Agriculture Ecosystem and Environment 165, 68-73.

  17. Influence of surface and subsurface tillage on soil physical properties and soil/plant relationships of planted loblolly pine

    SciTech Connect

    D. L. Kelting; H. L. Allen

    2000-05-01

    Soil tillage can improve tree survival and growth by reducing competing vegetation, increasing nutrient availability, improving planting quality, and improving soil physical properties. The authors conducted a tillage study with competition control and nutrient amendments to isolate the physical effects of tillage on tree growth. The objectives of this study were to understand: (1) how tillage affects soil physical properties; (2) the relationships between these properties and root growth; (3) linkages between root growth response and aboveground growth; and (4) tillage effects on aboveground growth. Four replicates of a 2x2 factorial combination of surface (disking) and subsurface (subsoiling) were installed on a well-drained, clay-textured subsoil, soil located on the Piedmont of North Carolina. Disking improved soil physical properties (reduced bulk density and increased aeration porosity) in the surface 20-cm of soil. Subsoiling improved soil physical properties at all depths in the planting row, with improvements still noted at 60-cm from the planting row in the surface 10-cm of soil. Rooting patterns followed the changes in soil physical properties. Despite improvements in soil physical properties and changes in rooting patterns, aboveground tree growth was not affected by tillage. The results of this study point to the need for better diagnostics for identifying sites were tillage is appropriate in situations where fertilization and vegetation control are planned. Potential factors to consider are presence and abundance of old root channels, soil shrink/swell capacity, soil structure, presence and depth to root restricting layers, and historical precipitation records.

  18. Application of different organic amendments in a gasoline contaminated soil: effect on soil microbial properties.

    PubMed

    Tejada, M; Gonzalez, J L; Hernandez, M T; Garcia, C

    2008-05-01

    The effects of four organic wastes, including cotton gin crushed compost (CC), poultry manure (PM), sewage sludge (SS) and organic municipal solid waste (MSW) on some biological properties of a Xerollic Calciorthid soil polluted with gasoline at two loading rates (5% and 10%) were studied in an incubation experiment. Three hundred grams of sieved soil (<2mm) were polluted with gasoline and mixed with PM at a rate of 10%, CC at a rate of 17.2%, SS at a rate of 23.1%, or MSW at a rate of 13.1%, applying to the soil the same amount of organic matter with each organic amendment. An unamended soil, non polluted (C) and polluted with gasoline at 5% (G1) and 10% (G2) rate were used as reference. Soil samples were collected after 1, 30, 60, 90, 120, 180 and 270 d of incubation and analyzed for microbial biomass carbon, respiration and dehydrogenase, urease, beta-glucosidase, phosphatase and arylsulfatase activities. At the end of the incubation period, soil biological properties were higher in organic amended soils than in C, G1 and G2 treatments. In particular, soil microbial biomass carbon and dehydrogenase, urease, beta-glucosidase, phosphatase and arylsulfatase activities increased 87.1%, 92.9%, 88.7%, 93.2%, 78.2% and 85.3%, respectively for CC-amended soils respect to G2, 85.7%, 82.3%, 87.3%, 92.2%, 76.7% and 83.6%, respectively for PM-amended soils; 82%, 90%, 84.8%, 89.9%, 74.1% and 80%, respectively for SS-amended soils; and 71.3%, 78.3% 26.2%, 38.2%, 79.7% and 88.6%, respectively for MSW-amended soils. Since the adsorption capacity of gasoline was higher in CC than the PM, SS and MSW-amended soils, it can be concluded that the addition of organic wastes with higher humic acid concentration is more beneficial for remediation of soils polluted with gasoline. PMID:17662598

  19. Physical and hydraulic properties of sediments and engineered materials associated with grouted double-shell tank waste disposal at Hanford

    SciTech Connect

    Rockhold, M.L.; Fayer, M.J.; Heller, P.R.

    1993-09-01

    Numerical models are used to predict the fate of contaminants in the environment for durations of 10,000 years and more. At the Hanford Site, these models are being used to evaluate the potential health effects and environmental impacts associated with the disposal of double-shell tank waste in grouted vaults. These models require information on the properties of the earthen and manufactured materials that compose the vault system and its surroundings. This report documents the physical and hydraulic properties of the materials associated with burial of grouted double-shell tank waste at the Hanford Site.

  20. Influence of the Soil Genesis on Physical and Mechanical Properties

    PubMed Central

    Marschalko, Marian; Yilmaz, I??k; Fojtová, Lucie; Kube?ka, Karel; Bouchal, Tomáš; Bednárik, Martin

    2013-01-01

    The paper deals with the influence of soil genesis on the physical-mechanical properties. The presented case study was conducted in the region of the Ostrava Basin where there is a varied genetic composition of the Quaternary geological structure on the underlying Neogeneous sediments which are sediments of analogous granulometry but different genesis. In this study, 7827 soil samples of an eolian, fluvial, glacial, and deluvial origin and their laboratory analyses results were used. The study identified different values in certain cases, mostly in coarser-grained foundation soils, such as sandy loam S4 (MS) and clayey sand F4 (CS). The soils of the fluvial origin manifest different values than other genetic types. Next, based on regression analyses, dependence was proved neither on the deposition depth (depth of samples) nor from the point of view of the individual foundation soil classes or the genetic types. The contribution of the paper is to point at the influence of genesis on the foundation soil properties so that engineering geologists and geotechnicians pay more attention to the genesis during engineering-geological and geotechnical investigations. PMID:23844398

  1. Influence of the soil genesis on physical and mechanical properties.

    PubMed

    Marschalko, Marian; Yilmaz, I??k; Fojtová, Lucie; Kube?ka, Karel; Bouchal, Tomáš; Bednárik, Martin

    2013-01-01

    The paper deals with the influence of soil genesis on the physical-mechanical properties. The presented case study was conducted in the region of the Ostrava Basin where there is a varied genetic composition of the Quaternary geological structure on the underlying Neogeneous sediments which are sediments of analogous granulometry but different genesis. In this study, 7827 soil samples of an eolian, fluvial, glacial, and deluvial origin and their laboratory analyses results were used. The study identified different values in certain cases, mostly in coarser-grained foundation soils, such as sandy loam S4 (MS) and clayey sand F4 (CS). The soils of the fluvial origin manifest different values than other genetic types. Next, based on regression analyses, dependence was proved neither on the deposition depth (depth of samples) nor from the point of view of the individual foundation soil classes or the genetic types. The contribution of the paper is to point at the influence of genesis on the foundation soil properties so that engineering geologists and geotechnicians pay more attention to the genesis during engineering-geological and geotechnical investigations. PMID:23844398

  2. Soil properties from preboring and driven pressuremeters

    E-print Network

    Terry, Thomas Andrew

    1986-01-01

    oading on a soil modulus and the par ameter n for the power 1 aw model descr ibing the influence of creep on a soi'1 modulus. As a resu1 t of thi s study a pressuremeter procedure is recommended in order to obtain the above parameters from a single.... 3 The Sigmoidal Model s 9. CREEP TESTS FOR THE INFLUENCE OF TIME 75 78 88 9. 1 Description of the Creep Tests for the Influence of Time and Test Procedure . 96 9. 2 Correction of the Creep Tests 9. 3 Analysis of the Creep Test 10...

  3. Constitutive Soil Properties for Mason Sand and Kennedy Space Center

    NASA Technical Reports Server (NTRS)

    Thomas, Michael A.; Chitty, Daniel E.

    2011-01-01

    Accurate soil models are required for numerical simulations of land landings for the Orion Crew Exploration Vehicle (CEV). This report provides constitutive material models for two soil conditions at Kennedy Space Center (KSC) and four conditions of Mason Sand. The Mason Sand is the test sand for LaRC s drop tests and swing tests of the Orion. The soil models are based on mechanical and compressive behavior observed during geotechnical laboratory testing of remolded soil samples. The test specimens were reconstituted to measured in situ density and moisture content. Tests included: triaxial compression, hydrostatic compression, and uniaxial strain. A fit to the triaxial test results defines the strength envelope. Hydrostatic and uniaxial tests define the compressibility. The constitutive properties are presented in the format of LSDYNA Material Model 5: Soil and Foam. However, the laboratory test data provided can be used to construct other material models. The soil models are intended to be specific to the soil conditions they were tested at. The two KSC models represent two conditions at KSC: low density dry sand and high density in-situ moisture sand. The Mason Sand model was tested at four conditions which encompass measured conditions at LaRC s drop test site.

  4. Agronomy & Soils Response of four cotton genotypes to N fertilization for root hydraulic conductance and lint yield

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In controlled environments, hydraulic conductance of cotton (Gossypium hirsutum L.) roots is affected by nitrate supply. Limited information is available on the influence of N on cotton root hydraulic conductance under field conditions. The objective of this study was to determine the effect of N fe...

  5. Zinc movement in sewage-sludge-treated soils as influenced by soil properties, irrigation water quality, and soil moisture level

    USGS Publications Warehouse

    Welch, J.E.; Lund, L.J.

    1989-01-01

    A soil column study was conducted to assess the movement of Zn in sewage-sludge-amended soils. Varables investigated were soil properties, irrigation water quality, and soil moisture level. Bulk samples of the surface layer of six soil series were packed into columns, 10.2 cm in diameter and 110 cm in length. An anaerobically digested municipal sewage sludge was incorporated into the top 20 cm of each column at a rate of 300 mg ha-1. The columns were maintained at moisture levels of saturation and unsaturation and were leached with two waters of different quality. At the termination of leaching, the columns were cut open and the soil was sectioned and analyzed. Zinc movement was evaluated by mass balance accounting and correlation and regression analysis. Zinc movement in the unsaturated columns ranged from 3 to 30 cm, with a mean of 10 cm. The difference in irrigation water quality did not have an effect on Zn movement. Most of the Zn applied to the unsaturated columns remained in the sludge-amended soil layer (96.1 to 99.6%, with a mean of 98.1%). The major portion of Zn leached from the sludge-amended soil layer accumulated in the 0- to 3-cm depth (35.7 to 100%, with a mean of 73.6%). The mean final soil pH values decreased in the order: saturated columns = sludge-amended soil layer > untreated soils > unsaturated columns. Total Zn leached from the sludge-amended soil layer was correlated negatively at P = 0.001 with final pH (r = -0.85). Depth of Zn movement was correlated negatively at P = 0.001 with final pH (r = -0.91). Multiple linear regression analysis showed that the final pH accounted for 72% of the variation in the total amounts of Zn leached from the sludge-amended soil layer of the unsaturated columns and accounted for 82% of the variation in the depth of Zn movement among the unsaturated columns. A significant correlation was not found between Zn and organic carbon in soil solutions, but a negative correlation significant at P = 0.001 was found between pH and Zn (r = -0.61).

  6. Anaerobic N mineralization in paddy soils in relation to inundation management, physicochemical soil fractions, mineralogy and soil properties

    NASA Astrophysics Data System (ADS)

    Sleutel, Steven; Kader, Mohammed Abdul; Ara Begum, Shamim; De Neve, Stefaan

    2013-04-01

    Anaerobic N mineralization measured from (saturated) repacked soil cores from 25 paddy fields in Bangladesh and was previously found to negatively related to soil N content on a relative basis. This suggests that other factors like soil organic matter (SOM) quality or abiotic factors instead control the anaerobic N mineralization process. We therefore assessed different physical and chemical fractions of SOM, management factors and various soil properties as predictors for the net anaerobic N mineralization. 1° First, we assessed routinely analyzed soil parameters (soil N and soil organic carbon, texture, pH, oxalate- and pyrophosphate-extractable Fe, Al, and Mn, fixed-NH4 content). We found no significant influences of neither soil mineralogy nor the annual length of inundation on soil N mineralization. The anaerobic N mineralization correlated positively with Na-pyrophosphate-extractable Fe and negatively with pH (both at P<0.01). At this stage it is, however, not known if these relations between net evolution of NH4 and pH and Fe content are causal or indirect. 2° Second, the 25 samples collected from farmers' fields were physically fractionated into particulate OM and silt and clay associated OM. The silt and clay sized OM was further chemically fractionated by oxidation with 6%NaOCl to isolate an oxidation-resistant OM fraction, followed by extraction of mineral bound OM with 10%HF thereby isolating the HF-resistant OM. None of the physicochemical SOM fractions were found useful predictors anaerobic N mineralization. The linkage between these chemical soil N fractions and N supplying processes actually occurring in the soil thus appears to be weak. Regardless, we hypothesize that variation in strength of N-mineral and N-OM linkages is likely to explain variation in bio-availability of organic N and proneness to mineralization. Yet, in order to separate kinetically different soil N fractions we then postulated that an alternative approach would be required, which instead isolates soil N fractions on the basis of bonding strength. In this respect bonding strength should be seen as opposite of proneness to dissolution of released N into water, the habitat of soil microorganisms mediating soil N mineralization. We hypothesize that soil N extracted by water at increasing temperatures would reflect such N fractions with increasing bonding strength, in turn equivalent to decreasing bio-availability. Although water has frequently been used to extract labile SOM, its use has mostly been limited to 100°C. 3° Third we developed sub critical water extraction (SCWE) at 100°C, 150°C and 200°C to isolate SOM fractions from the set of 25 paddy soil samples. In all cases, SCWE organic carbon (SCWE-OC) and N (SCWE-N) increased exponentially with the increase of temperature. SCWE preferentially extracted N over OC with increasing temperature. The efficiency of SCWE and the selectivity towards N were both lower in soils with increasingly reactive clay mineralogy. No correlations were found between the SCWE fractions and anaerobic N mineralization rate. In conclusion, SOM quantity and SOM quality, here represented by C and N distribution over physicochemical fractions, don't seem to dominantly determine anaerobic N mineralization in primarily young floodplain paddy soils. Other factors with exceeding control (pH and pyrophosphate extractable Fe) appear to exist. Possibly, the specific young genesis stage of most of the soils included (termed 'floodplain' soils) results in a limited availability of readily reducible Fe. Being an important alternative electron acceptor under submerged conditions, the availability of Fe, which is also controlled by pH, may be a bottleneck in the anaerobic N mineralization process. This needs to be further investigated by controlled incubation experiments with detailed follow-up of pH, redox potential, Fe in solution and mineral N.

  7. Application of organic amendments to restore degraded soil: effects on soil microbial properties.

    PubMed

    Carlson, Jennifer; Saxena, Jyotisna; Basta, Nicholas; Hundal, Lakhwinder; Busalacchi, Dawn; Dick, Richard P

    2015-03-01

    Topsoil removal, compaction, and other practices in urban and industrial landscapes can degrade soil and soil ecosystem services. There is growing interest to remediate these for recreational and residential purposes, and urban waste materials offers potential to improve degraded soils. Therefore, the objective of this study was to compare the effects of urban waste products on microbial properties of a degraded industrial soil. The soil amendments were vegetative yard waste compost (VC), biosolids (BioS), and a designer mix (DM) containing BioS, biochar (BC), and drinking water treatment residual (WTR). The experiment had a completely randomized design with following treatments initiated in 2009: control soil, VC, BioS-1 (202 Mg?ha(-1)), BioS-2 (403 Mg ha(-1)), and DM (202 Mg BioS ha(-1) plus BC and WTR). Soils (0-15-cm depth) were sampled in 2009, 2010, and 2011 and analyzed for enzyme activities (arylsulfatase, ?-glucosaminidase, ?-glucosidase, acid phosphatase, fluorescein diacetate, and urease) and soil microbial community structure using phospholipid fatty acid analysis (PLFA). In general, all organic amendments increased enzyme activities in 2009 with BioS treatments having the highest activity. However, this was followed by a decline in enzyme activities by 2011 that were still significantly higher than control. The fungal PLFA biomarkers were highest in the BioS treatments, whereas the control soil had the highest levels of the PLFA stress markers (P?soils decreased microbial stress levels; and microbial measures showed no statistical differences between BioS and VC treatments after 3 years of treatment. PMID:25673270

  8. Spectral Reflectance Estimates of Surface Soil Physical and Chemical Properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Optical diffuse reflectance sensing in visible and near-infrared wavelength ranges is one approach to rapidly quantify soil properties for site-specific management. The objectives of this study were (1) to determine the accuracy of the reflectance approach for estimating physical and chemical proper...

  9. Electrical properties of water in clay and silty soils

    Microsoft Academic Search

    Timo Saarenketo

    1998-01-01

    In order to better understand ground penetrating radar (GPR) results obtained in road surveys and site investigations, the dielectric properties and electrical conductivity of four silt and clay soils were measured at different densities and moisture contents ranging from oven dry material to the plastic state. The real parts K? and imaginary parts K? of the relative dielectric permittivity values

  10. COMMENTARY - SPATIAL VARIATION OF SOIL PROPERTIES RELATING TO VEGETATION CHANGES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bekele and Hudnall provide an interesting perspective on the spatial variation of soil chemical properties in a natural area undergoing transition from prairie to forest. Their focus is on the unique calcareous prairie ecosystem of Louisiana where prairie remnants are being encroached upon by the f...

  11. RADIOMETRIC ESTIMATION OF SOIL PROPERTIES USING MULTIPLE IMAGE SENSORS IN RICE PADDY AND DRYLAND FIELDS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An efficient way to detect spatial differences in crop and soil conditions at field scale is through image-based remote sensing. We report on three studies investigating the estimation of soil properties using bare-soil images. First, the ability of image data to estimate soil chemical property leve...

  12. Covariate selection with iterative principal component analysis for predicting physical soil properties

    E-print Network

    Covariate selection with iterative principal component analysis for predicting physical soil was to advance data-driven digital soil mapping techniques for the prediction of soil physical properties at high, and geostatistical techniques for effective spatial prediction of soil physical properties in a semiarid ecosystem

  13. Management-dependent soil property variability of Southeastern U.S. Coastal Plain plinthic kandiudults

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The National Cooperative Soil Survey (NCSS) defines a management or use-dependent property as a type of dynamic soil property which changes on a human time-scale due to anthropogenic disturbances (indicative of soil change). Interest in soil change and C sequestration has led to increased emphasis ...

  14. Soil physical properties, water depletion and crop development under traditional and conservation tillage in southern Spain

    Microsoft Academic Search

    F. Moreno; F. Pelegrín; J. E. Fernández; J. M. Murillo

    1997-01-01

    Tillage methods affect soil physical properties and, thus, have a direct influence on the replenishment and depletion of soil water storage and crop performance. This study was conducted to determine the effects of traditional and conservation tillage on soil physical properties, soil water replenishment and depletion, and crop development and yield under southern Spanish conditions. The experiments were carried out

  15. Variations in soil detachment rates after wildfire as a function of soil depth, flow properties, and root properties

    USGS Publications Warehouse

    Moody, John A.; Nyman, Peter

    2013-01-01

    Wildfire affects hillslope erosion through increased surface runoff and increased sediment availability, both of which contribute to large post-fire erosion events. Relations between soil detachment rate, soil depth, flow and root properties, and fire impacts are poorly understood and not represented explicitly in commonly used post-fire erosion models. Detachment rates were measured on intact soil cores using a modified tilting flume. The cores were mounted flush with the flume-bed and a measurement was made on the surface of the core. The core was extruded upward, cut off, and another measurement was repeated at a different depth below the original surface of the core. Intact cores were collected from one site burned by the 2010 Fourmile Canyon (FMC) fire in Colorado and from one site burned by the 2010 Pozo fire in California. Each site contained contrasting vegetation and soil types. Additional soil samples were collected alongside the intact cores and were analyzed in the laboratory for soil properties (organic matter, bulk density, particle-size distribution) and for root properties (root density and root-length density). Particle-size distribution and root properties were different between sites, but sites were similar in terms of bulk density and organic matter. Soil detachment rates had similar relations with non-uniform shear stress and non-uniform unit stream power. Detachment rates within single sampling units displayed a relatively weak and inconsistent relation to flow variables. When averaged across all clusters, the detachment rate displayed a linear relation to shear stress, but variability in soil properties meant that the shear stress accounted for only a small proportion of the overall variability in detachment rates (R2 = 0.23; R2 is the coefficient of determination). Detachment rate was related to root-length density in some clusters (R2 values up to 0.91) and unrelated in others (R2 values 2 value improved and the range of exponents became narrower by applying a multivariate regression model where boundary shear stress and root-length density were included as explanatory variables. This suggests that an erodibility parameter which incorporates the effects of both flow and root properties on detachment could improve the representation of sediment availability after wildfire.

  16. Rhamnolipid surface thermodynamic properties and transport in agricultural soil.

    PubMed

    Renfro, Tyler Dillard; Xie, Weijie; Yang, Guang; Chen, Gang

    2014-03-01

    Rhamnolipid is a biosurfactant produced by several Pseudomonas species, which can wet hydrophobic soils by lowering the cohesive and/or adhesive surface tension. Because of its biodegradability, rhamnolipid applications bring minimal adverse impact on the soil and groundwater as compared with that of chemical wetting agents. Subsequently, rhamnolipid applications have more advantages when used to improve irrigation in the agricultural soil, especially under draught conditions. In the presence of rhamnolipid, water surface tension dropped linearly with the increase of rhamnolipid concentration until the rhamnolipid critical micelle concentration (CMC) of 30 mg/L was reached. Below the CMC, rhamnolipid had linear adsorption isotherms on the soil with a partition coefficient of 0.126 L/kg. Rhamnolipid transport breakthrough curves had a broad and diffuse infiltration front, indicating retention of rhamnolipid on the soil increased with time. Rhamnolipid transport was found to be well represented by the advection-dispersion equation based on a local equilibrium assumption. When applied at concentrations above the CMC, the formed rhamnolipid micelles prevented rhamnolipid adsorption (both equilibrium adsorption and kinetic adsorption) in the soil. It was discovered in this research that rhamnolipid surface thermodynamic properties played the key role in controlling rhamnolipid transport. The attractive forces between rhamnolipid molecules contributed to micelle formation and facilitated rhamnolipid transport. PMID:24394947

  17. Limitation of Cell Elongation in Barley (Hordeum vulgare L.) Leaves Through Mechanical and Tissue-Hydraulic Properties.

    PubMed

    Touati, Mostefa; Knipfer, Thorsten; Visnovitz, Tamás; Kameli, Abdelkrim; Fricke, Wieland

    2015-07-01

    The aim of the present study was to assess the mechanical and hydraulic limitation of growth in leaf epidermal cells of barley (Hordeum vulgare L.) in response to agents which affect cellular water (mercuric chloride, HgCl2) and potassium (cesium chloride, CsCl; tetraethylammonium, TEA) transport, pump activity of plasma membrane H(+)-ATPase and wall acidification (fusicoccin, FC). Cell turgor (P) was measured with the cell pressure probe, and cell osmotic pressure (?) was analyzed through picoliter osmometry of single-cell extracts. A wall extensibility coefficient (M) and tissue hydraulic conductance coefficient (L) were derived using the Lockhart equation. There was a significant positive linear relationship between relative elemental growth rate and P, which fit all treatments, with an overall apparent yield threshold of 0.368 MPa. Differences in growth between treatments could be explained through differences in P. A comparison of L and M showed that growth in all except the FC treatment was co-limited through hydraulic and mechanical properties, though to various extents. This was accompanied by significant (0.17-0.24 MPa) differences in water potential (??) between xylem and epidermal cells in the leaf elongation zone. In contrast, FC-treated leaves showed ?? close to zero and a 10-fold increase in L. PMID:25907571

  18. STATE AND TRANSITION ECOSYSTEM MODELS: APPLICATION TO SOIL SURVEY AND DYNAMIC SOIL PROPERTIES DATABASES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Arid and semiarid rangelands are hypothesized to function as nonequilibrium systems. Models that capture these nonequilibrium dynamics at the ecological site level are called state and transition models (STMs). Through the literature, we examined the changes in soil properties that occurred as a r...

  19. Hydraulic Properties of Diatomaceous Structure on Physical Properties and Wire-line Logging - An example of off Sanriku, North Japan -

    NASA Astrophysics Data System (ADS)

    Ojima, T.; Saito, S.

    2013-12-01

    During Ocean Drilling Program (ODP) Leg. 186, two sites (Site 1150 and Site 1151) were drilled on the continental slope of the deep-sea forearc basin of northern Japan. Diatomaceous sediments were recovered Site 1150 (39° 10.9' N, 143° 19.9' E) and Site 1151 (38° 45.1' N, 143° 20.0' E), and the depth of each site is 1181.60 mbsf and 1113.60 mbsf, respectively. This area is under the influence of the Oyashio current and is one of the highly bio-productive regions of the North Pacific Ocean (Motoyama et al., 2004). The combination of high productivity and active tectonic deformation that often caused high rate accumulating of fossil and organic rich sediments. The onboard results of porosity measurements show high value (50-70 %) down to 1000 mbsf, and obviously higher than nearby subduction trench, Nankai Trough (Taylor and Fisher, 1993). There is a possibility that diatomaceous shell keep a frame structure from effective stress and load pressure. On another drilling site result, DSDP (Deep Sea Drilling Project) Leg. 19 located 60 km to the north of ODP sites, was reported high value of porosity, but recognized only shallow range (>500 mbsf) (Shephard and Bryant, 1980). We focused on the relationships between physical property, microstructure, and logging data at deep range(~1000 mbsf). We picked 14 samples to observe microstructure using SEM and measure permeability using flow-ump approach (1.5-4.5 MPa). Logging data were collected using wireline logging (Sacks and Suyehiro, 2003). Based on these results, it is expected that microstructure and logging can be integrated into a general model of core-log correlation. We observed many pores in and around diatom fossils using SEM even in the sample from deeper than 1000 mbsf, and measured pore size distribution and permeability at each depth. Generally, porosity decreases by effective stress and load pressure, and permeability also decrease with down hole. In this site, we recognized down hole decreases of pore space and preservations of diatom shell by using SEM. However, measured permeability displayed subtle patterns in downhole. These results can be considered that intact diatom shells don't always contribute to permeability, while fractured fabrics play good correlation with consolidation. Furthermore, correlations between water content ratio, permeability, and ithostratigraphic variance can be considered as a good index for hydraulic sedimental conditions. In this presentation, We show results of data integration of lithostratigraphy, measurements values, logging data, and physical properties.

  20. Correlating laboratory observations of fracture mechanical properties to hydraulically-induced microseismicity in geothermal reservoirs

    Microsoft Academic Search

    Stephen L. Karner

    2006-01-01

    To date, microseismicity has provided an invaluable tool for delineating the fracture network produced by hydraulic stimulation of geothermal reservoirs. While the locations of microseismic events are of fundamental importance, there is a wealth of information that can be gleaned from the induced seismicity (e.g. fault plane solutions, seismic moment tensors, source characteristics). Closer scrutiny of the spatial and temporal

  1. Relationship between spectral induced polarization and hydraulic properties of saturated and unsaturated sandstone

    Microsoft Academic Search

    Andrew Binley; Lee D. Slater; Melanie Fukes; Giorgio Cassiani

    2005-01-01

    There is growing interest in the use of geophysical methods for hydrological model parameterization. Empirical induced polarization (IP)–hydraulic conductivity (K) relationships have been developed, but these are only applicable to sediments in which the IP response shows limited variation with electrical current frequency. Here we examine the spectral IP response of samples taken from a UK sandstone aquifer and compare

  2. Organic Carbon Influences on Soil Particle Density and Rheological Properties

    SciTech Connect

    Blanco-Canqui, H; Lal, Rattan; Post, W M.; Izaurralde, R Cesar C.; Shipitalo, M. J.

    2006-07-01

    Soil particle density (rs) is not routinely measured and is assumed to range between 2.60 and 2.70 Mgm23 or to be a constant (2.65 Mgm23) when estimating essential properties such as porosity, and volumetric water and air relations. Values of rs for the same soil may, however, differ significantly from the standard range due to management induced changes in soil organic carbon (SOC) concentrations. We quantified the rs and Atterberg limits of a Rayne silt loam for five long-term (.22 yr) moldboard-plowed continuous corn (Zea mays L.; MP), no-till continuous corn (NT), no-till continuous corn with beef cattle manure (NTm), pasture, and forest systems.We also assessed the relationships of SOC concentration with rs and the Atterberg limits and the impact of rs on soil porosity. Mean rs across NT, NTm, and pasture (2.35 Mg m23) was |7% lower than that for MP in the 0- to 10-cm soil depth (2.52 Mg m23, P , 0.01). Forest had the lowest rs of all soils (1.79 Mg m23). The NTm caused a greater reduction in rs and a greater increase in SOC concentration, liquid limit (LL), plastic limit (PL), and plasticity index (PI) than NT. Surface soils under MP had the highest rs and rb and the lowest SOC concentration, LL, PL, and PI. The SOC concentration was correlated negatively with rs (r 2 5 0.75) and positively with Atterberg limits (r 2 . 0.64) at .20-cm depth. Estimates of soil porosity for NT, NTm, and pasture using the constant rs overestimated the ''true'' porosity by 12% relative to that using the measured rs.

  3. Evaluation of use of EM38-MK2 as a tool to understand field scale changes in soil properties

    NASA Astrophysics Data System (ADS)

    Gangrade, Sudershan

    Sustainable water resources management requires tools to help farmers identify variations in soil hydraulic characteristics so that precision irrigation schemes can be developed to optimize water use. In this study we use electromagnetic induction (EMI) to evaluate whether changes in the apparent electrical conductivity (sigmaalpha) of agricultural fields can be related to hydrologic processes. Field work for this study was completed at three different sites - 1) in different agricultural fields located in a watershed near Salri, Madhya Pradesh, India, 2) over an agricultural field located near Clemson University, SC, and 3) at a flood plain wetland restoration site near Madison, Wisconsin. The spatio-temporal study of sigmaalpha for fields in India revealed that sigmaalpha were related with the overall wetting and drying cycles at both seasonal and short term (daily) time scale. It was also found that there was a dependence of sigmaalpha patterns associated with the location of the field within the watershed. The short term EMI mappings revealed that sigmaalpha and changes in sigmaalpha both showed a similar spatial pattern for one of the fields. However, in contrast another field showed emergence of different patterns for both the sigmaalpha and changes in sigma alpha. Infiltrometer tests were performed to further investigate the field and a better relation, was observed with the measured hydraulic conductivity estimated using mini disk infiltrometer measurements and the changes in sigma alpha as against the absolute conductivity values.The cluster analysis performed for the fields in India showed that clustering performed using spatial data was able to capture the two different soil textures qualitatively observed in the field. A Monte Carlo analysis showed that the two clusters always had significantly different means showing that they belong to different clusters statistically as well. The purpose of the study performed in an agricultural field near Clemson University was to evaluate the relationships between sigmaalpha and soil hydraulic properties. At this site, repeated sigmaalpha measurements were made using Geonics EM-38 MK2 over two rain events. The range of sigmaalpha changed over time as a result of wetting and drying of the field to some extent but the within field spatial patterns of sigmaalpha were relatively consistent. The conductivity values correlated with the water content and finer particles obtained from the soil properties analysis with significant correlation values ranging from R = 0.36 - 0.78 for water content and R = 0.44-0.81 for % fines. The changes in sigmaalpha, however, were not found to show any linear relationship with changes in water content, water retention curves or basic infiltration rate obtained using infiltration tests. The exact reason behind such behavior are unknown and other parameters like fluid conductivity and temperature might be take into account for future studies to investigate it further. The last part of the study investigated application of EMI to capture the water content and soil variability at a restored wetland location near Madison, Wisconsin. The soil moisture was recorded at the field site using various soil moisture methods including a fiber optic distributed temperature sensor (DTS). The sigmaalpha weakly correlated with the soil moisture however spatial patterns in sigmaalpha and changes in sigmaalpha illustrated the overall wetting and drying of the field. Persistent wet and dry zones were observed along the DTS transect and indicate variations in soil hydrology. The sigmaalpha was able to qualitatively capture a similar trend. From all the studies performed at different field site, it can be concluded that Electromagnetic Induction can capture the variation in water content, soil texture and could also be related to the spatial patterns present in these soil properties The transient electromagnetic induction surveys however were not very efficient in capturing the changes especially for Clemson field site using the analysis technique adopted in this stu

  4. Effect of soil type and soil management on soil physical, chemical and biological properties in commercial organic olive orchards in Southern Spain

    NASA Astrophysics Data System (ADS)

    Gomez, Jose Alfonso; Auxiliadora Soriano, Maria; Montes-Borrego, Miguel; Navas, Juan Antonio; Landa, Blanca B.

    2014-05-01

    One of the objectives of organic agriculture is to maintain and improve soil quality, while simultaneously producing an adequate yield. A key element in organic olive production is soil management, which properly implemented can optimize the use of rainfall water enhancing infiltration rates and controlling competition for soil water by weeds. There are different soil management strategies: eg. weed mowing (M), green manure with surface tillage in spring (T), or combination with animal grazing among the trees (G). That variability in soil management combined with the large variability in soil types on which organic olive trees are grown in Southern Spain, difficult the evaluation of the impact of different soil management on soil properties, and yield as well as its interpretation in terms of improvement of soil quality. This communications presents the results and analysis of soil physical, chemical and biological properties on 58 soils in Southern Spain during 2005 and 2006, and analyzed and evaluated in different studies since them. Those 58 soils were sampled in 46 certified commercial organic olive orchards with four soil types as well as 12 undisturbed areas with natural vegetation near the olive orchards. The four soil types considered were Eutric Regosol (RGeu, n= 16), Eutric Cambisol (CMeu, n=16), Calcaric Regosol (RGca, n=13 soils sampled) and Calcic Cambisol (CMcc), and the soil management systems (SMS) include were 10 light tillage (LT), 16 sheep grazing (G), 10 tillage (T), 10 mechanical mowing (M), and 12 undisturbed areas covered by natural vegetation (NV-C and NV-S). Our results indicate that soil management had a significant effect on olive yield as well as on key soil properties. Among these soil properties are physical ones, such as infiltration rate or bulk density, chemical ones, especially organic carbon concentration, and biological ones such as soil microbial respiration and bacterial community composition. Superimpose to that soil management induced variability, there was a strong interaction with soil type and climate conditions. There was also a relatively high variability within the same soil management and soil type class, indicating farm to farm variability in conditions and history of soil management. Based on this dataset two different approaches were taken to: A) evaluate the risk of soil degradation based on a limited set of soil properties, B) assess the effect of changes in SMS on soil biodiversity by using terminal restriction profiles (TRFs) derived from T-RFLP analysis of amplified 16S rDNA as. The results indicates the potential of both approaches to assess the risk of soil degradation (A) and the impact on soil biodiversity (B) upon appropriate benchmarking to characterize the interaction between soil management and soil type References Álvarez, S., Soriano, M.A., Landa, B.B., and Gómez, J.A. 2007. Soil properties in organic olive orchards compared with that in natural areas in a mountainous landscape in southern Spain. Soil Use Manage 23:404-416. Gómez, J.A., Álvarez, S., and Soriano, M.A. 2009. Development of a soil degradation assessment tool for organic olive groves in southern Spain. Catena 79:9-17. Landa, B.B., Montes-Borrego, M., Aranda, S., Soriano, M.A., Gómez, J.A., and Navas-Cortés, J.A. 2013. Soil factors involved in the diversity and structure of soil bacterial communities in commercial organic olive orchards in Southern Spain. Environmental Microbiology Reports (accepted) Soriano, M.A., Álvarez, S., Landa, B.B., and Gómez, J.A. 2013. Soil properties in organic olive orchards following different weed management in a rolling landscape of Andalusia, Spain. Renew Agr Food Syst (in press), doi:10.1017/S1742170512000361.

  5. Degradation of fenamiphos in soils collected from different geographical regions: The influence of soil properties and climatic conditions

    Microsoft Academic Search

    Tanya Cáceres; Mallavarapu Megharaj; Ravi Naidu

    2008-01-01

    The persistence of fenamiphos (nematicide) in five soils collected from different geographical regions such as Australia, Ecuador and India under three temperature regimes (18, 25 and 37°C) simulating typical environmental conditions was studied. The effect of soil properties (soil pH, temperature and microbial biomass) on the degradation of fenamiphos was determined. The rate of degradation increased with increase in temperature.

  6. The effect of urban refuse compost and different tractors tyres on soil physical properties, soil erosion and maize yield

    Microsoft Academic Search

    Paolo Bazzoffi; Sergio Pellegrini; Andrea Rocchini; Miranda Morandi; Olga Grasselli

    1998-01-01

    Application of urban refuse compost to agricultural soil could help to solve municipalities' problems related to the increasing production of waste only if soil property improvement and environmental conservation can be demonstrated. The use of low-pressure tractor tyres is another proposal in modern agriculture for reducing soil compaction. This study thus aimed to detect the effects of both compost and

  7. Operational Downscaling of Soil Moisture Fields Using Ancillary Data

    Microsoft Academic Search

    G. Kim; A. P. Barros

    2001-01-01

    The scaling analysis of large-scale soil moisture data from the Southern Great Plains Hydrology experiment (SGP'97) showed that the scaling behavior of soil moisture is multifractal varying with the scale of observations and hydroclimatological conditions which can be explained with scaling behavior of soil hydraulic properties. These results suggested that it should be possible to use the spatial patterns of

  8. A Catalog of Vadose Zone Hydraulic Properties for the Hanford Site

    SciTech Connect

    Freeman, Eugene J; Khaleel, Raziuddin; Heller, Paula R

    2001-09-24

    The purpose of this catalog is to integrate all available soil physics data and information from vadose zone characterization and performance assessments into one usable, scientifically defensible document.

  9. Effects of Soil Properties on Phosphorus Subsurface Migration in Sandy Soils *1 *1 Project supported by the Natural Science Foundation of Zhejiang Province, China (No. R306011)

    Microsoft Academic Search

    Ming-Kui ZHANG

    2008-01-01

    The soil factors influencing the potential migration of dissolved and particulate phosphorus (P) from structurally-weak sandy subsoils were evaluated by means of soil column leaching experiments. Soil colloids were extracted from two types of soils to make the colloid-bound forms of P solution. Eight sandy soils with diverse properties were collected for packing soil columns. The effects of influent solutions

  10. The Composition and Properties of Some Texas Soils.

    E-print Network

    Fraps, G. S. (George Stronach)

    1907-01-01

    What Constitutes Soil Fertility; Causes of Small Crops; Maintaining Soil Fertitlity; Increasing Soil Fertility; Chemical Analysis of Soils; Value of Chemical Analysis; Pot Experiments; The United States Soil Survey; General Physical and Chemical...

  11. Determinants of arbuscular mycorrhizal communities - soil properties or land use?

    NASA Astrophysics Data System (ADS)

    Jansa, J.; Erb, A.; Oberholzer, H.-R.; Šmilauer, P.; Egli, S.

    2012-04-01

    Arbuscular mycorrhizal (AM) fungi accompanied terrestrial plants since some 500 million years of their evolution and are now widespread in all continents and virtually all soils of the world. They establish symbiotic interactions with a majority of extant higher plant species including most economically important plants. They are heavily implicated in plant nutrition, plant-soil carbon cycling, and tolerance to environmental stresses. Under field conditions, AM fungi usually form multispecies communities both in the soils and in plant roots, and it is becoming well established that various human interventions like cropping, crop rotation, tillage, and fertilization may all drive changes in the community composition of these fungi and, consequently, in the symbiotic benefits to the plants. Most of current evidence is stemming from individual short and long-term field trials, and the different studies usually employed diverse approaches, limiting the comparability of results across sites. Large scale sampling designs using unified research methods across different soil types and land use systems have hardly been employed so far. However, this would be imperative to allow direct comparisons of the effects of various environmental conditions (soil type, climate) and human land use practices on the indigenous soil-borne symbiotic microbes in general and the AM fungi in particular. To contribute to filling this gap, we conducted molecular profiling of AM communities in more than 150 Swiss agricultural soils, developed on a range of parent materials, covering a wide range of soil properties such as pH value, texture, carbon content and altitude, and including highly productive fields through alpine pastures. This study indicated strong correlations between AM fungal community patterns and features like soil pH and texture, as well as some consistent shifts in fungal communities due to specific aspects of land use like tillage or fertilization. These results thus appear to be of paramount importance for defining broadly valid thresholds in using AM communities as universal soil quality indicators. Expanding the current efforts on a global scale will be discussed.

  12. Development of an Air Permeameter for Monitoring Changes in Hydraulic Conductivity of Surface Soils due to Fire: Measurements Made Following the 2003 Aspen Fire in Sabino Canyon, Arizona

    NASA Astrophysics Data System (ADS)

    Chief, K.; Nijssen, B.; Ferre, P. A.; Ekwurzel, B.

    2003-12-01

    In the Southwest, severe fires can destroy as much as 90% of the vegetation and litter cover. Exposed, burned soils are highly vulnerable to intense monsoon rains, leading to increases in surface runoff, peak flows, and erosion rates. The Aspen Fire in the Coronado National Forest north of Tucson burned in excess of 80,000 acres and destroyed more than 300 structures. As part of an integrated investigation of the hydrologic impacts of this fire, we have developed an air permeameter to rapidly measure the hydraulic conductivity of burned and unburned soils. Results are shown that demonstrate the ability of the air permeameter to rapidly characterize changes in average permeability and spatial variability of permeability over large areas in rocky terrain.

  13. Effects of sediment transport and seepage direction on hydraulic properties at the sediment-water interface of hyporheic settings

    USGS Publications Warehouse

    Rosenberry, D.O.; Pitlick, J.

    2009-01-01

    Relations between seepage flux and hydraulic properties are difficult to quantify in fluvial settings because of the difficulty in measuring these variables in situ. Tests conducted in a 1.5-m diameter by 1.5-m tall sediment-filled tank indicate that hydraulic gradient increased and hydraulic conductivity (K) decreased following the onset of downward seepage but both parameters were little changed following the onset of upward seepage. Reductions in K during downward seepage were more pronounced when surface-water current was sufficient to mobilize sediment on the bed. Averaged ratios of K determined during upward seepage to K determined during downward seepage (Kup/Kdown) through a sand-and-gravel bed increased from 1.4 to 1.7 with increasing surface-water velocity, and decreased to slightly greater than 1 when the sediment bed became fully mobile. Kup/Kdown for tests conducted with a silt veneer on the bed surface was greater than 2 for all but the fastest surface-water velocities. Substantial reductions in K also were associated with a silt floc that formed on the bed surface during and following test runs. Although the silt floc was typically less than 0.5 mm in thickness, most of the hydraulic gradient was distributed across this thin layer. K of the thin silt floc was reduced by two to three orders of magnitude relative to the underlying sediment. Directional bias in K and relation between K and surface-water velocity require the presence or absence of a layer of lower-K sediment at or near the bed surface, without which no reduction in K and corresponding increase in hydraulic gradient can occur at the bed surface. The lack of prior observation of the consistent bias in K associated with seepage direction is somewhat surprising given the numerous studies where K has been measured in fluvial settings, but may be explained by the small value of the bias relative to the typical uncertainty associated with field determinations of K. If shown to exist in field settings, this bias and its relation to fluvial processes will be relevant to many studies conducted in hyporheic settings that require determination of fluxes across the sediment-water interface.

  14. The effect of model soil contamination with Cr, Cu, Ni, and Pb on the biological properties of soils in the dry steppe and semidesert regions of southern Russia

    NASA Astrophysics Data System (ADS)

    Kolesnikov, S. I.; Spivakova, N. A.; Kazeev, K. Sh.

    2011-09-01

    Model soil contamination with Cr, Cu, Ni, and Pb in the dry steppes and semideserts of southern Russia has worsened the biological soil properties. With respect to the degree of deterioration of the biological properties, the soils can be arranged in the following sequence: dark chestnut soils > chestnut soils > light chestnut soils > brown semidesert soils > sandy brown semidesert soils. The sequence of metal oxides according to the adverse effect on the biological soil properties is as follows: CrO3 > CuO ? PbO ? NiO.

  15. Quantification of Soil Physical Properties by Using X-Ray Computerized Tomography (CT) and Standard Laboratory (STD) Methods

    SciTech Connect

    Maria Ambert Sanchez

    2003-12-12

    The implementation of x-ray computerized tomography (CT) on agricultural soils has been used in this research to quantify soil physical properties to be compared with standard laboratory (STD) methods. The overall research objective was to more accurately quantify soil physical properties for long-term management systems. Two field studies were conducted at Iowa State University's Northeast Research and Demonstration Farm near Nashua, IA using two different soil management strategies. The first field study was conducted in 1999 using continuous corn crop rotation for soil under chisel plow with no-till treatments. The second study was conducted in 2001 and on soybean crop rotation for the same soil but under chisel plow and no-till practices with wheel track and no-wheel track compaction treatments induced by a tractor-manure wagon. In addition, saturated hydraulic (K{sub s}) conductivity and the convection-dispersion (CDE) model were also applied using long-term soil management systems only during 2001. The results obtained for the 1999 field study revealed no significant differences between treatments and laboratory methods, but significant differences were found at deeper depths of the soil column for tillage treatments. The results for standard laboratory procedure versus CT method showed significant differences at deeper depths for the chisel plow treatment and at the second lower depth for no-till treatment for both laboratory methods. The macroporosity distribution experiment showed significant differences at the two lower depths between tillage practices. Bulk density and percent porosity had significant differences at the two lower depths of the soil column. The results obtained for the 2001 field study showed no significant differences between tillage practices and compaction practices for both laboratory methods, but significant differences between tillage practices with wheel track and no-wheel compaction treatments were found along the soil profile for both laboratory methods. The K{sub s} measurements and CDE parameters revealed no significant differences between tillages and treatments. In essence, the CT method and CDE model both proved to be useful methods to quantify macropores and estimate solute transport parameters, respectively. Breakthrough curves were generated to observe the initial and final breakthrough of solute response along the soil matrix.

  16. CONSTRUCTION, MONITORING AND PERFORMANCE OF TWO SOIL LINERS

    EPA Science Inventory

    Two soil liners were built to determine the feasibility of building compact barriers to meet the hydraulic conductivity requirement of the U.S EPA (less than 1X10-7cm/s); assess variability of the liners hydraulic properties, and determine transit times of water and tracers throu...

  17. Leaching Properties of Naturally Occurring Heavy Metals from Soils

    NASA Astrophysics Data System (ADS)

    Zhang, M.; Hoshino, M.; Yoshikawa, M.; Hara, J.; Sugita, H.

    2014-12-01

    The major threats to human health from heavy metals are associated with exposure to arsenic, lead, cadmium, chromium, mercury, as well as some other elements. The effects of such heavy metals on human health have been extensively studied and reviewed by international organizations such as WHO. Due to their toxicity, heavy metal contaminations have been regulated by national environmental standards in many countries, and/or laws such as the Soil Contamination Countermeasures Act in Japan. Leaching of naturally occurring heavy metals from the soils, especially those around abandoned metal mines into surrounding water systems, either groundwater or surface water systems, is one of the major pathways of exposure. Therefore, understanding the leaching properties of toxic heavy metals from naturally polluted soils is of fundamentally importance for effectively managing abandoned metal mines, excavated rocks discharged from infrastructure constructions such as tunneling, and/or selecting a pertinent countermeasure against pollution when it is necessary. In this study, soil samples taken from the surroundings of abandoned metal mines in different regions in Japan were collected and analyzed. The samples contained multiple heavy metals such as lead, arsenic and chromium. Standard leaching test and sequential leaching test considering different forms of contaminants, such as trivalent and pentavalent arsenics, and trivalent and hexavalent chromiums, together with standard test for evaluating total concentration, X-ray Fluorescence Analysis (XRF), X-ray diffraction analysis (XRD) and Cation Exchange Capacity (CEC) tests were performed. In addition, sequential leaching tests were performed to evaluate long-term leaching properties of lead from representative samples. This presentation introduces the details of the above experimental study, discusses the relationships among leaching properties and chemical and mineral compositions, indicates the difficulties associated with remediation of naturally polluted sites, and emphasizes the importance of risk-based countermeasures against naturally occurring heavy metals. Keywords: Leaching properties, Control Factor, Naturally Occurring Heavy Metals, Lead, Arsenic, Chromium

  18. Does pH influence soil hydro-mechanical properties?

    NASA Astrophysics Data System (ADS)

    Chaplain, V.; Défossez, P.; Delarue, G.; Dexter, A. R.; Richard, G.; Tessier, D.

    2009-04-01

    Does pH influence soil hydro-mechanical properties ? V. Chaplain1, P. Défossez2, G. Delarue1, A.R. Dexter3, G. Richard3 and D. Tessier1. 1 UR INRA PESSAC RD 10, F-78026 Versailles cedex 2 UMR INRA/URCA FARE, 2 Esplanade Roland Garros, BP 224 F-51686 Reims cedex 2 3 UR INRA Sols 2163 Avenue de la Pomme de Pin - CS 40001 ARDON F-45075 Orléans Cedex 2 Corresponding author : chaplain@versailles.inra.fr Structure of soils and its dynamic, physico-chemistry of the interface are of a great importance in the fate of organic pollutants because it governs the accessibility of pollutants to micro-organisms. The soil structure of soils is related to physical parameters (texture, density, water content) but the physico-chemical properties of the interface is not considered. In this study we performed hydro-mechanical measurements on soil samples taken from the 42-plot long-term experiment in Versailles. Indeed six plo