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1

BOREAS HYD-1 Soil Hydraulic Properties  

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

2

Microbial effect on soil hydraulic properties  

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

3

Soil Texture Triangle: Hydraulic Properties Calculator  

NSDL National Science Digital Library

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

Saxton, Keith E., 1937-

4

Fractal models for predicting soil hydraulic properties: a review  

Microsoft Academic Search

Modern hydrological models require information on hydraulic conductivity and soil-water retention characteristics. The high cost and large spatial variability of measurements makes the prediction of these properties a viable alternative. Fractal models describe hierarchical systems and are suitable to model soil structure and soil hydraulic properties. Deterministic fractals are often used to model porous media in which scaling of mass,

D. Giménez; E. Perfect; W. J. Rawls; Ya. Pachepsky

1997-01-01

5

Spatial modelling of soil hydraulic properties integrating different supports  

NASA Astrophysics Data System (ADS)

Accurate estimates of soil hydraulic properties are needed for modelling.Soil hydraulic properties can be measured in different data supports.We used block sequential simulation to integrate data with different supports.We obtained the spatial distribution of SHP and associated uncertainty.Block sequential simulation performed better than direct sequential simulation.

Horta, Ana; Pereira, Maria João; Gonçalves, Maria; Ramos, Tiago; Soares, Amílcar

2014-04-01

6

Empirical equations for some soil hydraulic properties  

Microsoft Academic Search

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

Roger B. Clapp; George M. Hornberger

1978-01-01

7

Tillage and traffic effects on soil hydraulic properties and evaporation  

Microsoft Academic Search

Evaporation is a major component of the water loss from the soil whose structure is modified by traffic and tillage. This study was undertaken to analyse, in field conditions, the effect of tillage and traffic on soil structure and evaporation, and to determine the role of the change in hydraulic properties on soil drying using water transfer model. Three structures

J. F. Sillon; G. Richard; I. Cousin

2003-01-01

8

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

Microsoft Academic Search

The hydraulic properties of soil and their spatial structures are important for understanding soil moisture dynamics, land surface and subsurface hydrology, and contaminant transport. We investigated whether landscape features, including relative position on a slope, contribute to the variability of soil hydraulic properties in a complex terrain of a glacial till material. Using 396 undisturbed soil cores collected along two

Binayak P. Mohanty; Zak Mousli

2000-01-01

9

Modeling soil hydraulic properties for a wide range of soil conditions  

Microsoft Academic Search

This paper presents equations for estimating soil hydraulic properties such as bulk density (Db), field capacity (FC), permanent wilting point (PWP), and saturated hydraulic conductivity (Ksat) from soil composition (sand, silt, clay, organic matter, coarse fragments), and with increasing soil depth, for a wide range of natural soil types and conditions. The equations, derived from New Brunswick and Nova Scotia

Vincent Balland; Joseph A. P. Pollacco; Paul A. Arp

2008-01-01

10

Estimation of soil hydraulic properties with microwave techniques  

NASA Technical Reports Server (NTRS)

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.

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

1985-01-01

11

Hydraulic properties of mine soils with embedded lignitic fragments  

NASA Astrophysics Data System (ADS)

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

Gerke, Horst H.

2014-05-01

12

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

13

SOIL & WATER MANAGEMENT & CONSERVATION Landscape and Conservation Management Effects on Hydraulic Properties of a Claypan Soil Toposequence  

Microsoft Academic Search

Information on the effects of landscape and its interaction with management on soil hydraulic properties is scarce. Our objective was to investigate the effects and interactions of landscape position and conservation management systems (e.g., reduced tillage or permanent grass) on soil bulk density, saturated hydraulic conductivity (Ksat), soil water retention, and pore-size distributions for claypan soils in central Missouri. Landscape

S. H. Anderson; E. J. Sadler; K. A. Sudduth

14

Soil Properties, Classification, and Hydraulic Conductivity Testing: Draft Technical Resource Document for Public Comment.  

National Technical Information Service (NTIS)

The document is a compilation of available laboratory and field testing methods for the measurement of hydraulic conductivity (permeability) of soils along with background information on relevant soil properties and classification systems. This was develo...

D. W. Roberts

1984-01-01

15

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

PubMed Central

Structural porosity is a decisive property for soil productivity and soil environmental functions. Hydraulic properties in the structural range vary over time in response to management and environmental influences. Although this is widely recognized, there are few field studies that determine dominant driving forces underlying hydraulic property dynamics. During a three year field experiment we measured temporal variability of soil hydraulic properties by tension infiltrometry. Soil properties were characterized by hydraulic conductivity, effective macroporosity and Kosugi's lognormal pore size distribution model. Management related influences comprised three soil cover treatment (mustard and rye vs. fallow) and an initial mechanical soil disturbance with a rotary harrow. Environmental driving forces were derived from meteorological and soil moisture data. Soil hydraulic parameters varied over time by around one order of magnitude. The coefficient of variation of soil hydraulic conductivity K(h) decreased from 69.5% at saturation to 42.1% in the more unsaturated range (? 10 cm pressure head). A slight increase in the Kosugi parameter showing pore heterogeneity was observed under the rye cover crop, reflecting an enhanced structural porosity. The other hydraulic parameters were not significantly influenced by the soil cover treatments. Seedbed preparation with a rotary harrow resulted in a fourfold increase in macroporosity and hydraulic conductivity next to saturation, and homogenized the pore radius distribution. Re-consolidation after mechanical loosening lasted over 18 months until the soil returned to its initial state. The post-tillage trend of soil settlement could be approximated by an exponential decay function. Among environmental factors, wetting-drying cycles were identified as dominant driving force explaining short term hydraulic property changes within the season (r2 = 0.43 to 0.59). Our results suggested that beside considering average management induced changes in soil properties (e.g. cover crop introduction), a dynamic approach to hydrological modeling is required to capture over-seasonal (tillage driven) and short term (environmental driven) variability in hydraulic parameters.

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

2013-01-01

16

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

Microsoft Academic Search

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

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

2007-01-01

17

Spatial and temporal variability of soil hydraulic properties of topsoil affected by soil erosion  

NASA Astrophysics Data System (ADS)

This study is focused on the comparison of soil hydraulic properties of topsoil that is affected by erosion processes. In order to include variable morphological and soil properties along the slope three sites - Brumovice, Vidim and Sedl?any were selected. Two transects (A, B) and five sampling sites along each one were chosen. Soil samples were taken in Brumovice after the tillage and sowing of winter wheat in October 2010 and after the wheat harvest in August 2011. At locality Vidim and Sedl?any samples were collected in May and August 2012. Soil hydraulic properties were studied in the laboratory on the undisturbed 100-cm3 soil samples placed in Tempe cells using the multi-step outflow test. Soil water retention data points were obtained by calculating water balance in the soil sample at each pressure head step of the experiment. The single-porosity model in HYDRUS-1D was applied to analyze the multi-step outflow and to obtain the parameters of soil hydraulic properties using the numerical inversion. The saturated hydraulic conductivities (Ks) and unsaturated hydraulic conductivities (Kw) for the pressure head of -2 cm of topsoil were also measured after the harvest using Guelph permeameter and Minidisk tensiometer, respectively. In general soil water retention curves measured before and after vegetation period apparently differed, which indicated soil material consolidation and soil-porous system rearrangement. Soil water retention curves obtained on the soil samples and hydraulic conductivities measured in the field reflected the position at the elevation transect and the effect of erosion/accumulation processes on soil structure and consequently on the soil hydraulic properties. The highest Ks values in Brumovice were obtained at the steepest parts of the elevation transects, that have been the most eroded. The Ks values at the bottom parts decreased due to the sedimentation of eroded soil particles. The change of the Kw values along transects didn't show similar trends. However, the variability of values within both transects was low. Higher values were obtained in transect B, where the soil was more affected by erosion. The highest values of Ks as well as the value of Kw were also obtained in the steepest part of transect A in Vidim. This trend was not observed in transect B. The results corresponded with measured retention curves. Two different trends were shown in Sedl?any. While the highest values of Ks and Kw were found in the upper part of transect A, in the case of transect B the highest values were measured at the bottom of transect. Differences observed at both localities were caused by the different terrain attributes of both transects and extent of soil erosion. Acknowledgement: Authors acknowledge the financial support of the Ministry of Agriculture of the Czech Republic (QJ1230319).

Nikodem, Antonin; Kodesova, Radka; Jaksik, Ondrej; Jirku, Veronika; Klement, Ales; Fer, Miroslav

2014-05-01

18

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

19

Soil hydraulic properties in one-dimensional layered soil profile using layer-specific soil moisture assimilation scheme  

NASA Astrophysics Data System (ADS)

We developed a layer-specific soil-moisture assimilation scheme using a simulation-optimization framework, Soil-Water-Atmosphere-Plant model with genetic algorithm (SWAP-GA). Here, we explored the quantification of the soil hydraulic properties in a layered soil column under various combinations of soil types, vegetation covers, bottom boundary conditions and soil layering using idealized (synthetic) numerical studies and actual field experiments. We demonstrated that soil layers and vertical heterogeneity (layering arrangements) could impact to the uncertainty of quantifying soil hydraulic parameters. We also found that, under layered soil system, when the subsurface flows are dominated by upward fluxes, e.g., from a shallow water table, the solution to the inverse problem appears to be more elusive. However, when the soil profile is predominantly draining, the soil hydraulic parameters could be fairly estimated well across soil layers, corroborating the results of past studies on homogenous soil columns. In the field experiments, the layer-specific assimilation scheme successfully matched soil moisture estimates with observations at the individual soil layers suggesting that this approach could be applied in real world conditions.

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

2012-06-01

20

Hydraulic properties of saltstone and Z-Area soil  

Microsoft Academic Search

Basic hydraulic characteristics of disturbed and undisturbed Z-Area soil and of sandstone have been obtained. These data will aid modeling of the release of soluble ions from saltstone after disposal. Modeling of the release of soluble ions from saltstone and the migration of those materials to the water table has been underway for some time. Data needed for modeling were

J. R. Cook; C. A. Langton; E. L. Wilhite

1986-01-01

21

Effect of soil hydraulic properties on the relationship between the spatial mean and variability of soil moisture  

NASA Astrophysics Data System (ADS)

Knowledge of spatial mean soil moisture and its variability over time is needed in many environmental applications. We analyzed dependencies of soil moisture variability on average soil moisture contents in soils with and without root water uptake using ensembles of non-stationary water flow simulations by varying soil hydraulic properties under different climatic conditions. We focused on the dry end of the soil moisture range and found that the magnitude of soil moisture variability was controlled by the interplay of soil hydraulic properties and climate. The average moisture at which the maximum variability occurred depended on soil hydraulic properties and vegetation. A positive linear relationship was observed between mean soil moisture and its standard deviation and was controlled by the parameter defining the shape of soil water retention curves and the spatial variability of saturated hydraulic conductivity. The influence of other controls, such as variable weather patterns, topography or lateral flow processes needs to be studied further to see if such relationship persists and could be used for the inference of soil hydraulic properties from the spatiotemporal variation in soil moisture.

Martínez García, Gonzalo; Pachepsky, Yakov A.; Vereecken, Harry

2014-08-01

22

Effect of soil water repellency on soil hydraulic properties estimated under dynamic conditions  

NASA Astrophysics Data System (ADS)

SummarySoil research done over the past decades has proven that water repellent soils are widespread in all climates. Water repellency enhances the leaching of contaminants in the unsaturated zone by introducing preferential flow. In order to predict soil water fluxes in the unsaturated zone the accurate knowledge of the soil hydraulic properties (SHP) is mandatory. In this study the effect of water repellency on both imbibition and drainage SHP was studied. Inflow/outflow experiments were conducted in the laboratory for two soils and two artificially created hydrophobic mixtures. In the inflow/outflow experiments the pressure head at the bottom of the soil column was increased/decreased and the estimated SHP functions were obtained by means of inverse modeling. Inflow/outflow experiments were also conducted using ethanol instead of water in order to estimate the effect of liquid wetting properties on the estimated characteristic curves of the materials under study. The results showed that the water retention functions and the unsaturated hydraulic conductivity functions estimated from the dynamic experiments are strongly dependent on the degree of water repellency and the wetting/drying process.

Diamantopoulos, E.; Durner, W.; Reszkowska, A.; Bachmann, J.

2013-04-01

23

Modeling hydraulic properties of sandy soils of Niger using pedotransfer functions  

Microsoft Academic Search

Direct determination of soil hydraulic properties is often costly and laborious hence the use of indirect methods such as pedotransfer functions (PTFs). Despite progress made in PTF development in general, little evaluation of PTFs has been done for the sandy soils of Niger. We tested the ability of three PTFs, (Campbell, van Genuchten, and Vauclin) to determine soil water retention

C. Manyame; C. L. Morgan; J. L. Heilman; D. Fatondji; B. Gerard; W. A. Payne

2007-01-01

24

Effects of coarse-grained material on hydraulic properties and shear strength of top soil  

Microsoft Academic Search

Sidewalk failures associated with top soil of low shear strength are a common problem in urban areas. Mixing top soil with granite chips can be used to increase its permeability and shear strength. The effects of mixing granite chips with top soils on the hydraulic properties and shear strength under saturated and unsaturated conditions were investigated in this study. The

H. Rahardjo; I. G. B. Indrawan; E. C. Leong; W. K. Yong

2008-01-01

25

A comparison of land surface model soil hydraulic properties estimated by inverse modeling and pedotransfer functions  

Microsoft Academic Search

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

Ethan D. Gutmann; Eric E. Small

2007-01-01

26

Comparing the Multistep-Outflow and Evaporation Method for Determining Soil Hydraulic Properties  

NASA Astrophysics Data System (ADS)

Accurate knowledge of the soil hydraulic properties is necessary to simulate water flow in unsaturated soils. Among the transient experimental methods which allow the quick and simultaneous determination of the water retention and hydraulic conductivity function in the laboratory, the multistep-outflow and evaporation methods have become the most popular. Despite great effort to improve the experimental setups and evaluation techniques, much less attention has been devoted to the investigation of the agreement of soil hydraulic properties obtained from different methods applied to the same soil. Therefore we analyzed different soil types in order to compare the hydraulic properties obtained by the multistep-outflow method and the simplified evaporation method by Schindler (1980), advanced by Peters and Durner (2008). We found that for soils, where all requirements for the validity of the Richards equation as water flow process description are sufficiently fulfilled, i.e. for homogeneous media with consolidated pore systems and in the absence of "dynamic effects", the two methods gave very similar results. Problems arose for non-consolidated soils, where the evaporation process leads to a settling of the porous medium, or for swelling and shrinking soils. A particular problem was the establishment of identical initial conditions, when using the very same soil column for both experiments. Furthermore, dynamic effects, expressed by local non-equilibrium between water content and pressure head, and caused by limited gas-phase permeability or local heterogeneity, caused problems in the interpretation of the derived hydraulic properties.

Schelle, H.; Peters, A.; Durner, W.

2009-04-01

27

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

NASA Technical Reports Server (NTRS)

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

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

1986-01-01

28

The effect of dynamic changes in soil bulk density on hydraulic properties: modeling approaches  

NASA Astrophysics Data System (ADS)

Natural and artificial processes, like rainfall-induced soil surface sealing or mechanical compaction, disturb the soil structure and enhance dynamic changes of the related pore size distribution. These changes may influence many aspects of the soil-water-plant-atmosphere system. One of the easiest measurable variables is the soil bulk density. Approaches are suggested that could model the effect of the change in soil bulk density on soil permeability, water retention curve (WRC) and unsaturated hydraulic conductivity function (HCF). The resulting expressions were calibrated and validated against experimental data corresponding to different soil types at various levels of compaction, and enable a relatively good prediction of the effect of bulk density on the soil hydraulic properties. These models allow estimating the impact of such changes on flow processes and on transport properties of heterogeneous soil profiles.

Assouline, Shmuel

2014-05-01

29

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

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

30

Numerically predicting seepage gradient forces and erosion: Sensitivity to soil hydraulic properties  

NASA Astrophysics Data System (ADS)

SummaryResearch has suggested that streambank seepage can be an important mechanism of bank instability; however, limited information is available on the level of soil characterization necessary to accurately predict seepage gradient forces and erosion. The objective of this research was to quantify the expected range of predicted seepage gradients for various degrees of site characterization. Uncertainty analysis on seepage gradient predictions was performed relative to variability in soil hydraulic properties. A two-dimensional unsaturated/saturated groundwater flow model was used to simulate a homogeneous soil layer for sand and loamy sand soils packed at various bulk densities, ? b. A pedotransfer function (ROSETTA), designed to estimate unsaturated hydraulic properties from surrogate soil data (i.e., texture and bulk density), was used to derive the saturated hydraulic conductivity, K s, and water retention parameters for various levels of site information (i.e., only textural class; percent sand, silt, and clay (%SSC); %SSC and ? b; and %SSC, ? b, and K s). Statistical distributions were derived for each soil hydraulic parameter and Monte Carlo simulations were performed to generate distributions of maximum seepage gradient. The deviation in predicted seepage gradient was calculated using assumed baseline conditions. Ranges in predicted soil hydraulic parameters and maximum seepage gradients were considerably reduced when using %SSC as compared to soil texture. Therefore, at a minimum, soil samples should be taken for particle size analysis. For ? b between 1450 and 1500 kg m -3, soil hydraulic parameters could be derived using ROSETTA and inputting %SSC, with little additional benefit provided by measuring ? b and/or K s. When the ? b was less than 1450-1500 kg m -3, inputting ? b and/or K s consistently reduced the magnitude of deviations from the baseline and therefore should be measured from undisturbed soil samples. The opposite was observed for ? b greater than 1450-1500 kg m -3 due to discrepancies between ROSETTA-derived and actual values of soil hydraulic parameters other than K s. Considerable deviations (i.e., around 20%) were observed in seepage gradients under this scenario. When ROSETTA-derived and actual values of soil hydraulic parameters more closely matched, inputting ? b and/or K s benefitted seepage gradient predictions as deviations in seepage gradients were less than 5% for the sand and loamy sand soils. Therefore, it is vital to quantify all soil hydraulic parameters for high ? b soils and textures with a wide range in %SSC.

Fox, Garey A.; Heeren, Derek M.; Wilson, Glenn V.; Langendoen, Eddy J.; Fox, Amanda K.; Chu-Agor, Maria L.

2010-08-01

31

Identification of soil hydraulic properties over the full moisture range by inverse modeling of evaporation experiments  

NASA Astrophysics Data System (ADS)

Semi-arid regions represent a significant portion of earth's surface. Reliable quantification of the soil water balance in these regions plays a key role for estimating ground water recharge and a proper management of water use. However, modeling of soil water movement in relatively dry soils and the accurate prediction of the evaporative fluxes to the atmosphere and the deep drainage to the groundwater, pose considerable challenges. Simulation of these processes relies on a proper conceptual model for water flow and an adequate parameterization of the soil hydraulic properties. While the experimental characterization of soil water retention in dry soils has made significant progress, for instance by the introduction and more widespread use of the dewpoint method, the measurement of unsaturated hydraulic conductivity in medium to dry soils remains a challenge. In dry soils, the determination of hydraulic conductivity is difficult, because the measurement of the water potential gradient is not trivial. The aim of this study was to identify soil hydraulic properties by inverse modeling, with a particular focus on the medium to dry moisture range. We conducted evaporation experiments on large soil columns under laboratory conditions. An extended instrumentation using tensiometres and relative humidity sensors enabled us to monitor water potential in the columns from full wetness to air dryness. We found that the unsaturated hydraulic conductivity functions which lead to a good match between model-predicted and observed flux and potential data differed markedly from those obtained from traditional conceptual models of hydraulic conductivity. For validation purposes, we tested the predictive capabilities of the identified hydraulic functions under boundary conditions which were different from those used for parameter identification, and found them to be good predictors of system behavior.

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

2014-05-01

32

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

National Technical Information Service (NTIS)

Over the years, data have been obtained on soil hydraulic properties at the Hanford Site. This study helps to identify, compile, and interpret all available data for the principal soil types in the 200 Areas plateau. Information on particle-size distribut...

R. Khaleel E. J. Freeman

1995-01-01

33

Soil Hydraulic Properties Estimation from Inverse Modeling of L-Band Brightness Temperature  

NASA Astrophysics Data System (ADS)

The structure of the soil surface layer plays an important role for the water distribution in the soil and water exchange between the soil and atmosphere. We present a coupled inversion procedure of time lapse L-band brightness temperature data to estimate the soil hydraulic properties in the shallow subsurface of ploughed silt loam bare soil. The complex inversion procedure connected a one-dimensional vertical water flow modeling and a radiative transfer model. The L-band radiometer Jülbara (1.4 GHz, wavelength ? ? 21.4 cm) with dual-mode horn antenna and an infrared camera (IR) were mounted on a fixed tower at 10 m above the measurement plot for estimation of the brightness temperature and the soil surface temperature, respectively. The measurement plot with dimensions of 12 m by 8 m was prepared manually. In-situ soil temperature and soil moisture sensors were installed at four depths (2, 5, 10 and 30 cm) to monitor the lateral and vertical dynamics. Soil samples were collected in the field for laboratory estimation of the soil hydraulic properties. To simulate the subsurface water flow, the hydrological simulator HYRDUS 1D was used, and was coupled to a coherent radiative transfer model to calculate the unsaturated soil hydraulic properties. The empirical model of Wang and Schmugge for complex dielectric permittivity of the soil was used to link the hydrological and radiative transfer model. The effective soil temperature and correction for soil surface roughness were applied in the modeling procedure. Coupled inversion was performed to estimate five parameters of Mualem-van Genuchten model minimizing the difference between the measured and modeled brightness temperatures. Irrespectively of the complexity of the inversion scheme, modeled and measured brightness temperature values showed reasonably good agreement, especially in the temporal evolution. The estimated soil hydraulic properties were in good agreement with the hydraulic properties obtained from the laboratory analysis of the soil samples. The results confirmed the potential for non-invasive characterization of soil hydraulic properties using L-band brightness temperature data.

Dimitrov, M.; Vanderborght, J.; Jadoon, K. Z.; Schwank, M.; Kostov, K.; Vereecken, H.

2011-12-01

34

Vertical variations of soil hydraulic properties within two soil profiles and its relevance for soil water simulations  

NASA Astrophysics Data System (ADS)

Numerical simulations of soil water dynamics can be valuable tools for the assessment of different soil and land management practices. For accurate simulations, the soil hydraulic properties (SHP), i.e. the hydraulic conductivity and water retention function have to be properly known. They can be either estimated from physical soil properties by pedotransfer functions (PTF) or measured. In most studies, soil profiles are analyzed and sampled with respect to their pedogenic horizons. While considerable effort has been put on horizontal spatial SHP variations, vertical changes within soil profiles have not been analyzed in detail. Therefore, the objectives of this study were (i) the SHP measurement along vertical transects within two soil profiles, (ii) to evaluate their spatial variation and correlation with physical soil properties, and (iii) to assess the impact of the SHP determination method and its spatial discretization on simulated soil water balance components. Two soils, an agriculturally used silty-loam Chernozem and a forested sandy Cambisol were sampled in 0.05 m increments along vertical transects. The parameters of a dual porosity model were derived using the evaporation method and scaling was applied to derive representative mean SHP parameters and scaling factors as a measure of spatial variability. State-space models described spatial variations of the scaling factors by physical soil properties. Simulations with HYDRUS 1D delivered the soil water balance for different climatic conditions with the SHP being estimated from horizon-wise PTFs, or discretized either sample-wise, according to the pedogenic horizons, or as hydrologically relevant units (hydropedological approach). Considerable SHP variations were found for both soil profiles. In the Chernozem, variations of the hydraulic conductivity were largest within the ploughed Ap-horizon and could be attributed to variations in soil structure (macropores). In the subsoil, soil water retention showed a gradual decrease within each horizon. The observed water retention variations could be described by state-space models that comprised the contents of clay and total carbon, whereas variations of the hydraulic conductivity were described by clay content and total porosity. The hydraulic conductivity in the Cambisol was slightly undulating throughout the profile. Here, water retention was largest in the upper part of the profile and considerably decreased within the lower part of the Bhs-horizon. Simulated soil water balance components differed distinctly between the SHP discretizations. Compared to observed soil water contents, the simulations where the SHP were given by small-scale layers or hydropedological units performed best for both experimental sites. The different SHP discretizations mainly affected the estimated drainage losses and the simulated crop transpiration under medium to dry climatic conditions. The study confirmed the importance of an adequate spatial SHP discretization. The results indicate that SHP estimations by PTFs or the standard horizon-mean sampling strategy might fail to parameterize soil water simulations, especially in structured soils. The presented hydropedological approach showed a way to receive good simulation results by reducing the SHP observation density.

Schwen, Andreas; Zimmermann, Michael; Bodner, Gernot

2014-08-01

35

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

SciTech Connect

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.

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

1999-12-01

36

Effects of spatial variability of soil hydraulic properties on water dynamics  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

37

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

NASA Astrophysics Data System (ADS)

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.

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

2012-03-01

38

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

USGS Publications Warehouse

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.

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

2012-01-01

39

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

SciTech Connect

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

Khaleel, R.; Freeman, E.J.

1995-10-01

40

Saturated hydraulic conductivity in relation to physical properties of soils in the Nsukka Plains, southeastern Nigeria  

Microsoft Academic Search

Information on the most important physical properties that influence the saturated hydraulic conductivity (Ks) of soils is useful in modelling water and solute movement during ponded infiltration and in estimating both temporal and spatial variation in Ks. In this study the Ks of 18 sites with different land use histories on a watershed in the Nsukka plains of southeastern Nigeria

J. S. C. Mbagwu

1995-01-01

41

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

NASA Astrophysics Data System (ADS)

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

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

2009-04-01

42

Inverse estimation of the unsaturated soil hydraulic properties from tension disc infiltrometer data and electrical resistivity data  

NASA Astrophysics Data System (ADS)

An accurate and time-efficient estimation of unsaturated soil hydraulic properties in the field remains a challenge. Tension-infiltrometry is often used to determine unsaturated soil hydraulic conductivity and its spatial variability in the field. Due to capillary flow, a 3-D wetting bulb develops under the tension infiltrometer. The shape of the bulb depends mainly on the unsaturated soil hydraulic properties. In classical tension-infiltrometer experiments only the amount of infiltrated water is measured with time and used to infer soil hydraulic conductivity. Electrical resistivity tomography (ERT) offers the possibility to image the spatial distribution of bulk soil electrical conductivity from a set of apparent electrical resistivity (ER) measurements, which is related through a petrophysical model to the soil water content. Therefore, apparent ER data contain information about the 3-D structure of the wetting bulb, which may be exploited to infer soil hydraulic properties. Whether a combination of tension-infiltrometer and apparent ER data can be used to estimate soil hydraulic parameters was investigated in numerical experiments. Instead of using a tomographic inversion of the apparent ER data, i.e. ERTomography, to derive the spatial distribution of the wetting bulb from which subsequently hydraulic parameters are derived, we explore the potential of a joint inversion approach that derives hydraulic parameters directly from apparent ER data. The combined infiltration and apparent ER datasets showed that the soil hydraulic parameters could be inverted from a single infiltration experiment, which is not possible when only infiltration data are used for inversion. Application of the proposed method was performed on a silt clay loam. Results have shown accurate estimations on the saturated hydraulic conductivity and on the hydraulic parameters of the water retention curve.

Schneider, S.; Swinnen, R.; Pessel, M.; Vanderborght, J.; Coquet, Y.; Vachier, P.

2009-04-01

43

Development of soil hydraulic soil properties below ancient forest, planted forest and grassland  

NASA Astrophysics Data System (ADS)

A number of serious flood events in recent years have focused attention on flood prevention and mitigation and modelling work suggests that climate change will lead to an increase in the intensity and frequency of flood events in many areas. To understand how soil hydraulic characteristics develops in relation to facilitating the infiltration and storage of storm rainfall, a hypothetical pedogensis sequence was first developed and then tested by investigating a grassland site and four Scots pine (Pinus sylvestris) forests of different ages in the Scottish Highlands. These sites are: grassland, six and 45 year-old Scots pine plantations, remnant 300 year old individual Scots pines and a 4000 year old Caledonian Forest. The soil characteristics measured were: field saturated hydraulic conductivity (Kfs) using a constant head well permeameter, root numbers and proportion were estimated from soil pits and soil cores were taken for three different soil depths (0.06 - 0.10, 0.16 - 0.20 and 0.26 to 0.40m) for laboratory measurements to estimate organic matter, soil water release curves, macro-pores, and X - ray tomography measured pore connectivity and soil pore structure. It was observed that cutting down of the plantation increased organic matter because of the increase of dead biomass and decreased pore connectivity, which resulted in reduced hydraulic conductivity during the early years of re-afforestation. Where older trees were left, after cutting and removing younger trees; the range of OM, hydraulic conductivity, pore connectivity, and macropores remained similar to and older Scots pine plantation (45 years old). The undisturbed Ancient Caledonian remnant forest (approximately 4000 years old) was observed to have remarkably heterogeneous soil characteristics, providing extreme values of Kfs (12 to 4992 mm hr-1), OM, and macropores. Such ranges of soil characteristics were considered to be the optimum to reduce local flooding, because the soil matrix could transport high intensity storm rainfall and re-direct storm rainfall to deeper layers and the presence of micropores and larger quantity of OM provides a greater area to store. This combination of soil characteristics would slow down the flow of rainfall to ground water reservoirs and rivers and reduce flood peaks.

Archer, Nicole; Otten, Wilfred; Schmidt, Sonja; Bengough, Glyn; Bonell, Mike; Shah, Nadeem

2014-05-01

44

Overview of inert tracer experiments in key Belgian soil types: Relation between transport and soil morphological and hydraulic properties  

NASA Astrophysics Data System (ADS)

To investigate relations between solute transport, soil properties, and experimental conditions, we summarize results from leaching experiments that we carried out in a range of soils, at different scales (column (0.3-1.0 m ID, 1.0 m length) and field plot scale), and using different leaching rates (0.5-30 cm d-1). The lateral mixing regime and longitudinal dispersion were derived from time series of tracer concentrations at several depths in the soil. Field- and column-scale transport were similar in loam and silt loam soils. The mixing regime was related to soil morphological features, such as vertical tongues, stratification, macropores, and a water-repellent layer. The dispersion increased in all soils more than linearly with increasing leaching rate, implying that the dispersivity is not an intrinsic soil characteristic. The change of dispersivity with leaching rate was linked to the unsaturated hydraulic conductivity using a multidomain conceptualization of the pore space.

Vanderborght, J.; Vanclooster, M.; Timmerman, A.; Seuntjens, P.; Mallants, D.; Kim, D.-J.; Jacques, D.; Hubrechts, L.; Gonzalez, C.; Feyen, J.; Diels, J.; Deckers, J.

2001-12-01

45

Estimating the unsaturated hydraulic conductivity from theoretical models using simple soil properties  

Microsoft Academic Search

The knowledge of the unsaturated hydraulic conductivity is one of the prerequisites to describe water flow and solute transport in soils. In this paper we examined the quality of 11 different theoretical models to predict the unsaturated hydraulic conductivity for a wide variety of soils. The hydraulic conductivity models were fitted to 44 measured curves using a quasi Newton parameter

H. Vereecken

1995-01-01

46

Dynamic changes in hydraulic properties of soils irrigated with treated wastewater  

NASA Astrophysics Data System (ADS)

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 cause to soil degradation and crop yield reduction. This study aims to describe and quantify the dynamic changes in the soil hydraulic properties resulting from the use of TW for irrigation. Combining between analysis of data from a set of complementary laboratory experiments involving infiltration, evaporation, swelling and saturated hydraulic conductivity measurements, and numerical simulations provide quantitative estimates of the negative impact of TW for irrigation on the soil properties. It appears that the soil degradation is a dynamic process that depends on the duration of the exposure to the low-quality irrigation water. The intensity of the changes distributes with depth and results from the irrigation management applied and the efficiency of the leaching process induced by rainfall. The negative impact is the result between increase of soil sodicity and changes in soil wettability. Such negative impact may affect the hydrological balance components at the field and at the regional scale.

Assouline, Shmuel

2014-05-01

47

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

USGS Publications Warehouse

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

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

2009-01-01

48

Parameter Estimation for Soil Hydraulic Properties Using Zero-Offset Borehole Radar: Analytical Method  

Microsoft Academic Search

ity and the van Genuchten . In this study, we apply this approach to measurements of wetting front advance Inverse methods to obtain soil hydraulic parameters are becoming made under simulated field conditions. increasingly popular, due to their more rapid, complete, and robust estimations of hydraulic parameters compared with traditional direct Standard methods typically determine the hydraulic methods. We present

Dale F. Rucker

49

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

SciTech Connect

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.

Shakofsky, S.

1995-03-01

50

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

USGS Publications Warehouse

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

Shakofsky, S. M.

1995-01-01

51

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

52

Time-lapse Ground-Penetrating Radar for Deriving Soil Hydraulic Properties  

NASA Astrophysics Data System (ADS)

A profound understanding of subsurface hydrological processes demands a detailed description of hydraulic parameter distributions at the pertinent scale of interest. However, characterizing soil hydraulic properties remains a challenge, especially for field scale studies. Accurate high-resolution GPR measurements of soil water dynamics have shown promise to alleviate this challenge. In recent years, ASSESS-GPR, a field scale test site for advancing Ground-Penetrating Radar methods has been successfully established in Heidelberg (e.g., Buchner et al, 2012 or Klenk, 2012). Permanently installed TDR sensor profiles allow for an independent, corroborating dataset which can serve as basis for hydrologic modeling. In such a well-controlled experimental setup, we can achieve a very high relative precision for non-invasively monitoring soil water dynamics with GPR (Klenk, 2012). We can furthermore study the dynamics of the capillary fringe in different materials through time-lapse GPR measurements during pumping experiments. For example, as Dagenbach et al (2013) have shown, information can be gained about the appropriate form of a hydraulic parameterization. We here expand on these previous works by presenting a set of experiments, where the water table has been raised and subsequently lowered in a multi-step fashion over the course of several days. We discuss the non-invasive, high-resolution monitoring of the corresponding subsurface water dynamics by time-lapse GPR and thoroughly assess potentials for deriving hydraulic parameters for the different materials through electromagnetic modeling of the GPR response for said materials under the measured forcing.

Klenk, Patrick; Jaumann, Stefan; Roth, Kurt

2014-05-01

53

Estimation of the Unsaturated Hydraulic Soil Properties From Joint Inversion of Tension Infiltrometer and ERT Measurements: Numerical Experiments  

NASA Astrophysics Data System (ADS)

An accurate and time-efficient estimation of unsaturated hydraulic soil properties in the field remains a challenge. Tension-infiltrometry is often used to determine unsaturated hydraulic soil properties and their spatial variability in the field. Due to capillary flow, a 3-D wetting bulb, which depends on the unsaturated hydraulic soil properties, the radius of the infiltrometer disk, and the applied water tension, develops under a tension infiltrometer. Electrical resistivity tomography (ERT) offers the possibility to image the spatial distribution of bulk soil electrical conductivity, which is related through a petrophysical model to the soil water content. Therefore, ERT data contain information about the 3-D structure of the wetting bulb, which may be exploited to infer hydraulic soil properties. A combination of tension-infiltrometer and ERT data for an inverse estimation of the soil hydraulic parameters was tested in a numerical experiment. Both 3-D water flow and electrical potential fields were simulated with the SWMS_3-D model using the van Genuchten hydraulic functions and the Rhoades petrophysical model. Simulated infiltration and simulated apparent electrical resistivities were subsequently inverted using the PEST software. Inversion of the combined infiltration and ERT datasets showed that the hydraulic parameters could be inverted from a single infiltration experiment, which is not possible when only infiltration data are used in the inversion. Also petrophysical parameters could be inverted simultaneously with hydraulic parameters from the combined ERT-infiltrometer data. These results demonstrate the potential of the method by considering additional information about the structure of the wetting bulb which is contained in ERT data.

Schneider, S.; Vanderborght, J.; Kemna, A.; Pessel, M.; Coquet, Y.

2007-12-01

54

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

NASA Technical Reports Server (NTRS)

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

Eagleson, Peter S.; Jasinski, Michael F.

1988-01-01

55

Assessing Tillage Effects on Soil Hydraulic Properties via Inverse Parameter Estimation using Tension Infiltrometry  

NASA Astrophysics Data System (ADS)

Hydraulic properties are key factors controlling water and solute movement in soils. While several recent studies have focused on the assessment of the spatial variability of hydraulic properties, the temporal dynamics are commonly not taken into account, primarily because its measurement is costly and time-consuming. However, there is extensive empirical evidence that these properties are subject to temporal changes, particularly in the near-saturated range where soil structure strongly influences water flow. One main source of temporal variability is soil tillage. It can improve macroporosity by loosening the soil and thereby changing the pore-size distribution. Since these modifications are quite unstable over time, the pore space partially collapses after tillage. This effect should be largest for conventional tillage (CT), where the soil is ploughed after harvest every year. Assessing the effect of different tillage treatments on the temporal variability of hydraulic properties requires adequate measurement techniques. Tension infiltrometry has become a popular and convenient method providing not only the hydraulic conductivity function but also the soil rentention properties. The inverse estimation of parameters from infiltration measurements remains challenging, despite some progress since the first approach of Šimůnek et al. (1998). Measured data like the cumulative infiltration, the initial and final volumetric water content, as well as independently measured retention data from soil core analysis with laboratory methods, have to be considered to find an optimum solution describing the soil's pore space. In the present study we analysed tension infiltration measurements obtained several times between August 2008 and December 2009 on an arable field in the Moravian Basin, Lower Austria. The tillage treatments were conventional tillage including ploughing (CT), reduced tillage with chisel only (RT), and no-tillage treatment using a direct seeding technique (NT). Infiltration measurements were supplemented by retention data for dryer conditions (-10 to -300 kPa) as determined by pressure plate extraction on steel core samples. The HYDRUS 2D/3D software package was used to inversely fit the parameters of suitable soil retention models to the data. Beside the most common model of Van Genuchten (1978), we also assessed the lognormal distribution model proposed by Kosugi (1994) and the dual porosity approach of Durner (1994). We will show that a dual porosity model best fits the infiltration data. It allows the retention curve to account for both the cumulative infiltration (structure-controlled flow) as well as the measured retention data points (texture-controlled flow). The pressure plate extraction data are used to determine one of the shape-determining parameter sets of the model equation. As the tillage effect on the temporal variability is expected to be negligible for texture-controlled water flow, these parameters are set constant with time for each tillage treatment. All remaining model parameters were inversely determined by the infiltration data. The advantage of a bimodal retention model is greatest when macropores strongly contribute to water movement. This can be observed especially under conventional tillage, where a strong increase of macropores is caused by annual ploughing, but also for reduced (oder minimum) tillage treatments, where biopores from earthworm burrows and dead plant roots increase macropore flow.

Schwen, Andreas; Bodner, Gernot; Loiskandl, Willibald

2010-05-01

56

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

NASA Technical Reports Server (NTRS)

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

Gutmann, Ethan D.; Small, Eric E.

2007-01-01

57

Organic matter and aggregate size interaction on structural changes and soil hydraulic properties  

NASA Astrophysics Data System (ADS)

It was hypothesized that the interaction between organic matter (OM) content and aggregate size could affect the mechanisms of structural degradation and, consequently, the soil hydraulic properties. Thus, the objective was to investigate the effects of this interaction on the saturated hydraulic conductivity (K_s) without raindrop impact and on the infiltration rate (IR) under raindrop impact. Samples of sandy loam soil (Humic Dystrudept) with 2.3 and 3.5% OM content (designated low- and high-OM soils, respectively) were collected from two adjacent fields. Each sample was sieved to obtain aggregate sizes of <2, 2-4, and 4-6 mm. Slaking, swelling and dispersion rates, and K_s were measured for each soil and aggregate size. The K_s was determined in disturbed soil columns by means of a constant-head device. Likewise, IR, soil loss and crust micromorphology of each soil and for each aggregate size were measured in a rainfall simulator. For each aggregate size, K_s values of the high-OM soil were, in general, significantly higher than those of the low-OM soil. Moreover, there was a significant interaction between the aggregate size and the OM content in their effects on the K_s. These results suggest that the degradation of the soil structure during the wetting and leaching process was greater in the low-OM soil, and resulted mainly from differences in aggregate slaking during wetting. The slaking rates were > 93 and < 6.7% for the low- and high-OM soils, respectively. Under rainfall, IR decreased as the cumulative rainfall increased, because of seal formation at the soil surface. The final IR values ranged from 4.2 to 5.2 mm h-1 in the low-OM soil and from 5.8 to 10.8 mm h-1 in the high-OM soil, and the larger the aggregate size, the higher was the final IR. The effects of the aggregate size on seal formation rate and final IR were more pronounced in the high-OM soil. The low aggregate stability and the high dispersivity of the low-OM soil allowed the breakdown and dispersion of even the largest aggregates, therefore a dense and thick (> 1 mm) crust developed for all the aggregate sizes. In contrast, the high aggregate stability and low dispersivity of the high-OM soil limited the breakdown and dispersion of the aggregates at the surface, therefore the IR values were high, with relatively large differences between those found with large and small aggregate sizes. The soil loss was significantly higher for aggregates of <2 mm than for the other two sizes although, unlike the final IR, no significant interaction between soil OM content and aggregate size was found.

Lado, M.; Ben-Hur, M.

2003-04-01

58

Near-saturated surface soil hydraulic properties under different land uses in the St Denis National Wildlife Area, Saskatchewan, Canada  

NASA Astrophysics Data System (ADS)

Surface soil hydraulic properties are key factors controlling the partition of rainfall and snowmelt into runoff and soil water storage, and their knowledge is needed for sound land management. The objective of this study was to evaluate the effects of three land uses (native grass, brome grass and cultivated) on surface soil hydraulic properties under near-saturated conditions at the St Denis National Wildlife Area, Saskatchewan, Canada. For each land use, water infiltration rates were measured using double-ring and tension infiltrometers at -0.3, -0.7, -1.5 and -2.2 kPa pressure heads. Macroporosity and unsaturated hydraulic properties of the surface soil were estimated. Mean field-saturated hydraulic conductivity (Kfs), unsaturated hydraulic conductivity at -0.3 kPa pressure head, inverse capillary length scale () and water-conducting macroporosity were compared for different land uses. These parameters of the native grass and brome grass sites were significantly (p < 0.1) higher than that of the cultivated sites. At the -0.3 kPa pressure head, hydraulic conductivity of grasslands was two to three times greater than that of cultivated lands. Values of were about two times and values of Kfs about four times greater in grasslands than in cultivated fields. Water-conducting macroporosity of grasslands and cultivated fields were 0.04% and 0.01% of the total soil volume, respectively. Over 90% of the total water flux at -0.06 kPa pressure head was transmitted through pores > 1.36 × 10-4 m in diameter in the three land uses. Land use modified near-saturated hydraulic properties of surface soil and consequently may alter the water balance of the area by changing the amount of surface runoff and soil water storage.

Bodhinayake, Waduwawatte; Si, Bing Cheng

2004-10-01

59

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

60

SATURATED - UNSATURATED HYDRAULIC PROPERTIES OF SUBBASE COURSE MATERIAL AND SUBGRADE SOIL  

NASA Astrophysics Data System (ADS)

In order to evaluate the rainwate r storage and infiltration properties of the permeable pavement by unsaturated seepage analysis or gas-liquid two-phase flow analysis, it is important to know the unsaturated hydraulic properties of materials wh ich constitute the pavement. For this reason, we showed the unsaturated hydraulic properties of porous asphalt material s but we have not clarified the relation between the performance of the permeable pavement and the properties of all constituti on materials. In this paper, we try to determine the unsaturated hydraulic properties of subbase course and subgrade materials that greatly affect the rainwater storage and infiltration properties of the permeable pavement. We show from experiments that water retention characteristic and the un saturated hydraulic properties of subbase course and subgrade materials well match the van Genuchten model and the Irmay model.

Yano, Takao; Nishiyama, Satoshi; Nakashima, Shin-Ichiro; Moriishi, Kazushi; Ohnishi, Yuzo

61

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

SciTech Connect

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.

NONE

1995-04-01

62

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

NASA Astrophysics Data System (ADS)

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

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

2008-07-01

63

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

NASA Technical Reports Server (NTRS)

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

Eagleson, P. S.

1985-01-01

64

Determining soil hydraulic properties by inverse method in one-dimensional unsaturated flow  

SciTech Connect

For physically based models, the hydraulic conductivity function and the effective fluid saturation function are the most important parameters affecting water and solute movements in the vadose zone. Direct parameter measurements in heterogeneous soils are very difficult and scale-dependent. The inverse approach is an indirect and interesting way to estimate hydrodynamic parameters. In-situ soil water retention and hydraulic conductivity relations were determined for a layered soil from knowledge of initial and boundary conditions and observed pressure heads during infiltration, evaporation, and redistribution. We will present efficient algorithms for inverse problems applied to both synthetic and real test cases. The location and the number of observation points are very important; the number of observations must be sufficient, i.e., the variables have to be measured for each layer of the soil. Large differences in sensitivity are observed among the various model parameters. 22 refs., 1 fig., 4 tabs.

Lehmann, F.; Ackerer, P. [Universite Louis Pasteur, Strasbourg (France)

1997-01-01

65

Variation of surficial soil hydraulic properties across land uses in the southern Blue Ridge Mountains, North Carolina, USA  

NASA Astrophysics Data System (ADS)

SummaryA full understanding of hydrologic response to human impact requires assessment of land-use impacts on key soil physical properties such as saturated hydraulic conductivity, bulk density, and moisture retention. Such properties have been shown to affect watershed hydrology by influencing pathways and transmission rates of precipitation to stream networks. Human land use has been shown to influence these soil physical properties as a result of erosion, compaction, and pore structure evolution. Our objective was to characterize soil physical properties under three land-use classes (forest, pasture, and managed lawn) in the southern Blue Ridge Mountains of southwestern North Carolina. A total of 90 points were sampled (30 in each land-use class) throughout a 983 km 2 study area. Saprolitic and alluvial soils were emphasized, and sites were selected that showed consistent land-use history over a period of at least 30 years. Particle size distribution, in situ saturated hydraulic conductivity (measured using an Amoozemeter compact constant head permeameter), bulk density, and volumetric moisture content at field capacity were measured at each point. Forest soils demonstrated markedly lower bulk densities and higher infiltration rates, and water holding capacities, than lawn and pasture soils. No soil property significantly differed between pasture and lawn. Mean values for each property were as follows (forest = F, lawn = L, pasture = P): saturated hydraulic conductivity (mm h -1) - F = 63, L = 7, P = 8; bulk density (g cm -3) - F = 0.8, L = 1.2, P = 1.2; volumetric moisture content (%) - F = 72%, L = 42%, P = 39%. Particle size distributions did not significantly differ among land-use classes or parent materials, and the differences between the hydraulic properties of forest vs. nonforest soils were attributed to compaction associated with land management practices. The magnitudes of differences between forest and nonforest infiltration rates suggest that widespread conversion of forest to other land uses in this region will be accompanied by decreased infiltration and increased overland flow, potentially significantly altering water budgets and leading to reduced baseflows and impaired water quality.

Price, Katie; Jackson, C. Rhett; Parker, Albert J.

2010-03-01

66

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

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

67

9 - SOIL HYDRAULIC PROPERTIES OF SIEROZEM SOILS AND FIELD CROP OBSERVATIONS FOR RZWQM APPLICATION IN FERGANA  

Microsoft Academic Search

Located in the Aral Sea Basin, Uzbekistan suffers from environmental problems related to soil salinization and water scarcity. Under conditions of limited resources, crop production must be maintained at expense of minimum inputs but aiming the achievement of maximum returns. The search of the best combination between the available resources and crop yield can be eased by the interactive use

G. V. Stulina; M. R. Cameira

68

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

69

Soil hydraulic and physico-chemical properties of Ultisols and Inceptisols in south-eastern Nigeria  

Microsoft Academic Search

Understanding soil water dynamics and storage is important to avoid crop failure on highly weathered, porous and leached soils. The aim of the study was to relate soil moisture characteristics to particle-size distributions and chemical properties. On average, Atterberg limits were below 25% in the A-horizon and not more than26.56% in the B-horizon, whereas soil bulk density was between 1.27

Charles A. Igwe; Mehdi Zarei; Karl Stahr

2012-01-01

70

Saturated hydraulic conductivity of soils in the Southern Piedmont of Georgia, USA: Field evaluation and relation to horizon and landscape properties  

Microsoft Academic Search

Saturated hydraulic conductivity (Ks) is one of the soil properties used most often to predict soil behavior and suitability for a variety of uses. Because of the difficulty in Ks measurement and its variability with depth and across the landscape, Ks is commonly predicted from other more easily evaluated properties including texture, clay mineralogy, bulk density, pedogenic structure and cementation.

L. T. West; M. A. Abreu; J. P. Bishop

2008-01-01

71

RETC CODE FOR QUANTIFYING THE HYDRAULIC FUNCTIONS OF UNSATURATED SOILS  

EPA Science Inventory

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

72

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

73

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

NASA Astrophysics Data System (ADS)

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/.

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

2013-12-01

74

Estimation and analysis of soil hydraulic properties through infiltration experiments: comparison of BEST and DL fitting methods  

Microsoft Academic Search

The BEST method (Beerkan estimation of soil transfer parameters through infiltration experiments) appears promising and easy to estimate not only saturated hydraulic conductivity but also water reten- tion and hydraulic characteristics. However, few tests have been conducted to test the methodology. This study involved field BEST infiltration experiments for three layers (surface, 15 and 30 cm) for each of three

X. Xu; G. Kiely; C. Lewis

2009-01-01

75

Estimating Saturated Hydraulic Conductivity from Soil Water Retention Curve using Neural Networks  

Microsoft Academic Search

Study of soil hydraulic properties like saturated and unsaturated hydraulic conductivity is required in the environmental investigations. Since, direct measurement of soil hydraulic properties is time consuming and expensive, indirect methods such as pedotransfer function and artificial neural networks (ANN) have been developed based on the readily available soil characteristics. In this study, we used soil water retention data i.e.

B. Ghanbarian-Alavijeh; A. M. Liaghat; S. Sohrabi

2009-01-01

76

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

77

Probing pore-scale modeling methods to determine saturated/unsaturated hydraulic properties of highly structured agricultural soils  

NASA Astrophysics Data System (ADS)

Novel pore-scale modelling methods are becoming popular in geophysical and petrophysical applications to determine single and multi-phase transport properties of sedimentary rocks (e.g., sandstones, carbonates, etc.). However, the implication of these techniques for soils is very limited to simple single phase flow simulations on small domains (without comparison to any laboratory measurements), or to simple pore-network approaches with more qualitative results which capture some important flow features (an especially strong limitation of these methods is usage of cylindrical pore-throats capable of containing only one fluid). In this contribution we try to determine saturated/unsaturated hydraulic properties and water retention curve (WRC) using computational fluid dynamics (CFD) and pore-network modelling approaches for three soil samples taken from different layers from an agricultural field in Suzdal area of Russian Plain. Cylindrical samples with radius of 5 cm and volume of approximately 100 cubic cm were scanned using X-ray microtomography device SkyScan-1172 with the resolution of around 15 microns. After thresholding and bunarization the biggest possible cubes were subcropped and used for further analysis. At first, single-phase velocity fields and permeabilities were determined numerically solving Stokes equation directly on digitized 3D images. Same images were used for extraction of the pore-networks using maximal inscribed ball method. Single and two-phase (water-air) flow properties, including drainage curve (WRC) and relative permeabilities, were determined in these networks considering triangular and rectangular pore cross sections. Due to the unconventional samplers it was impossible to measure transport properties on the samples used for scanning and modelling. All measurements (bulk density, grain/aggregate size distributions, hydraulic conductivity and WRC, etc.) were performed using numerous (30-50 samples for each soil layer) conventionally obtained samples and used for comparison against scanning and modelling results. Our results show that both modelling methods provide similar single-phase flow results, so that simplified pore-network geometry is representative for given soil samples. Comparison of simulated and measured values for unsaturated characteristics also showed very promising results. Finally, we compare simulated relative permeabilities to that obtained using conventional Mualem-van Genuchten approaches and its modifications (Durner's WRCs for multi-modal pore-sizes). Future prospects of the pore-scale modelling technique in soil science applications are outlined and current challenges are discussed.

Gerke, Kirill; Korost, Dmitry; Umarova, Aminat; Vasilyev, Roman; Karsanina, Marina

2013-04-01

78

Estimating field-scale soil hydraulic properties and petrophysical models through joint GPR/hydrological measurement inversion  

NASA Astrophysics Data System (ADS)

As ground-penetrating radar (GPR) travel times are highly sensitive to transient and non-uniform water distributions, they are potentially quite useful for inferring soil hydraulic parameters. In this research, multiple-offset cross-borehole GPR travel times are used jointly with additional hydrological measurements to estimate field-scale soil hydraulic parameters through inversion. Our approach allows for estimation of 1) the soil hydraulic parameters, 2) the parameters describing the petrophysical model (the constitutive model relating the dielectric constant to the porosity and water saturation), and 3) spatial correlation model parameters of the permeability field. A synthetic example involving the point injection of water and the simultaneous collection of nearby borehole neutron probe and GPR measurements is first considered to examine the impact of inaccurate petrophysical models on the estimation of soil hydraulic parameters. Errors can be introduced when applying a petrophysical model to a situation with conditions different from those for which the model was derived (e.g., when non-site-specific or laboratory-scale petrophysical models are applied to field-scale measurements). Our synthetic study suggests that small errors in the petrophysical model cause substantial errors in the soil hydraulic parameter estimates. However, we show that these errors may be overcome through joint estimation of the petrophysical model itself and the soil hydraulic parameters. Finally, the approach is applied to a GPR-neutron probe data set collected at the Hanford DOE site in Washington, allowing us to draw conclusions regarding the strengths and weaknesses of the approach in a real-world, 3-D setting. This work was supported in part by the U.S. Dept. of Energy under Contract No. DE-AC03-76SF00098.

Kowalsky, M. B.; Finsterle, S. A.; John, P. E.; Hubbard, S. S.; Rubin, Y.; Majer, E. L.; Ward, A. L.; Gee, G. W.

2004-12-01

79

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

Microsoft Academic Search

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)

Shakofsky

1995-01-01

80

The efficiency of various approaches to obtaining estimates of soil hydraulic properties  

Microsoft Academic Search

A formal analysis was carried out to evaluate the efficiency of the different methods in predicting water retention and hydraulic conductivity. Efficiency can be defined in terms of effort, cost or value of information. The analysis identified the contribution of individual sources of measurement errors to the overall uncertainty. The value of information summarises the quality of the prediction, the

Budiman Minasny; Alex B McBratney

2002-01-01

81

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

82

Multivariate distributions of soil hydraulic parameters  

NASA Astrophysics Data System (ADS)

Statistical distributions of soil hydraulic parameters have to be known when synthetic fields of soil hydraulic properties need to be generated in ensemble modeling of soil water dynamics and soil water content data assimilation. Pedotransfer functions that provide statistical distributions of water retention and hydraulic conductivity parameters for textural classes are most often used in the parameter field generation. Presence of strong correlations can substantially influence the parameter generation results. The objective of this work was to review and evaluate available data on correlations between van Genuchten-Mualem (VGM) model parameters. So far, two different approaches were developed to estimate these correlations. The first approach uses pedotransfer functions to generate VGM parameters for a large number of soil compositions within a textural class, and then computes parameter correlations for each of the textural classes. The second approach computes the VGM parameter correlations directly from parameter values obtained by fitting VGM model to measured water retention and hydraulic conductivity data for soil samples belonging to a textural class. Carsel and Parish (1988) used the Rawls et al. (1982) pedotransfer functions, and Meyer et al. (1997) used the Rosetta pedotransfer algorithms (Schaap, 2002) to develop correlations according to the first approach. We used the UNSODA database (Nemes et al. 2001), the US Southern Plains database (Timlin et al., 1999), and the Belgian database (Vereecken et al., 1989, 1990) to apply the second approach. A substantial number of considerable (>0.7) correlation coefficients were found. Large differences were encountered between parameter correlations obtained with different approaches and different databases for the same textural classes. The first of the two approaches resulted in generally higher values of correlation coefficients between VGM parameters. However, results of the first approach application depend on pedotransfer relationships not only within a given textural class but also on pedotransfer relationships within other textural classes since the pedotransfer relationships are developed across the database containing data for several textural classes. Therefore, joint multivariate parameter distributions for a specific class may not be sufficiently accurate. Currently PTF may give the best prediction of the parameter itself, but they are not designed to estimate correlations between parameters. Covariance matrices for soil hydraulic parameters present an additional type of pedotransfer information that needs to be acquired and used whenever random sets of those parameters are to be generated.

Qu, Wei; Pachepsky, Yakov; Huisman, Johan Alexander; Martinez, Gonzalo; Bogena, Heye; Vereecken, Harry

2014-05-01

83

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

USGS Publications Warehouse

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

Ebel, Brian A.; Nimmo, John R.

2010-01-01

84

Spatial Variability of Physical Properties of a Tropical Soil. II. Soil Water Retention Curves and Hydraulic Conductivity.  

National Technical Information Service (NTIS)

The characterization of a field site from the soil physics point of view, the improvement of the use of soil and water resources under a particular condition and the development of means for controlling the dynamics of soil-water movement are presented. S...

K. Reichardt P. L. Libardi S. V. Queiroz F. Grohmann

1976-01-01

85

Monitoring and modeling the soil hydraulic behavior in stony soils  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

86

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

NASA Astrophysics Data System (ADS)

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.

Kleimeier, Christian; Lennartz, Bernd

2014-05-01

87

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

NASA Technical Reports Server (NTRS)

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

Eagleson, Peter S.; Jasinski, Michael F.

1988-01-01

88

Soil Structure and Saturated Hydraulic Conductivity  

NASA Astrophysics Data System (ADS)

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.

Houskova, B.; Nagy, V.

89

Soil Properties  

NSDL National Science Digital Library

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.

Todd, Carrie D.

90

Modification of hydraulic conductivity in granular soils using waste materials.  

PubMed

This paper evaluates the use of waste products such as silica fume and fly ash in modification of the granular soils in order to remove some environmental problems and create new useful findings in the field of engineering. It is known that silica fume and fly ash, as well as clay material, are used in geotechnical engineering because of their pozzolanic reactivity and fineness to improve the soil properties needed with respect to engineering purposes. The main objective of this research project was to investigate the use of these materials in geotechnical engineering and to improve the hydraulic properties of soils by means of grouting. For this reason, firstly, suitable grouts in suspension forms were prepared by using silica fume, fly ash, clay and cement in different percentages. The properties of these cement-based grouts were then determined to obtain the desired optimum values for grouting. After that, these grouts were penetrated into the soil samples under pressure. The experimental work indicates that these waste materials and clay improved the physical properties and the fluidity of the cement-based grouts and they also decreased the hydraulic conductivity of the grouted soil samples by sealing the voids of the soil. The results of this study have important findings concerning the use of these materials in soil treatment and the improvement of hydraulic conductivity of the soils. PMID:15120433

Akbulut, S; Saglamer, A

2004-01-01

91

Measuring Soil Hydraulic Conductivity With Microwaves  

NASA Technical Reports Server (NTRS)

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.

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

1985-01-01

92

THE RETC CODE FOR QUANTIFYING THE HYDRAULIC FUNCTIONS OF UNSATURATED SOILS  

EPA Science Inventory

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

93

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

NASA Technical Reports Server (NTRS)

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

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

1983-01-01

94

DEMONSTRATION BULLETIN: HYDRAULIC FRACTURING OF CONTAMINATED SOIL  

EPA Science Inventory

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

95

Comparison of artificial neural network and regression pedotransfer functions for prediction of soil water retention and saturated hydraulic conductivity  

Microsoft Academic Search

Modeling water flow and solute transport in vadose zone requires knowledge of soil hydraulic properties, which are water retention and hydraulic conductivity curves. As an alternative to direct measurement, indirect determination of these functions from basic soil properties using pedotransfer functions (PTFs) has attracted the attention of researchers in a variety of fields such as soil scientists, hydrologists, and agricultural

Hasan Merdun; Özer Ç?nar; Ramazan Meral; Mehmet Apan

2006-01-01

96

Effect of gravel on hydraulic conductivity of compacted soil liners  

Microsoft Academic Search

How much gravel should be allowed in low-hydraulic-conductivity, compacted soil liners To address this question, two clayey soils are uniformly mixed with varying percentages of gravel that, by itself, has a hydraulic conductivity of 170 cm\\/s. Soil\\/gravel mixtures are compacted and then permeated. Hydraulic conductivity of the compacted gravel\\/soil mixtures is less than 1 [times] 10[sup [minus]7] cm\\/s for gravel

Thomas L. Shelley; David E. Daniel

1993-01-01

97

The Soil Hydraulic Response to Disturbance and Recovery  

NASA Astrophysics Data System (ADS)

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

Zimmermann, B.; Elsenbeer, H.

2006-12-01

98

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

99

Framework for predicting hydraulic properties of calcareous arid lands  

NASA Astrophysics Data System (ADS)

In arid areas, the availability of reliable data on soil hydraulic properties such as the water retention and the hydraulic conductivity curves, particularly of calcareous soils, is low. Such data are needed as input to mathematical models used to support arid land restoration and combating desertification studies. This paper aims at sharing new and pertinent research results that are of interest to the scientific community involved in such studies. The objective of our study was to (1) explore the interaction between soil hydraulic properties, and other physical and chemical properties, (2) test three data mining techniques for developing predictive functions, and (3) set up a framework for predicting soil hydraulic properties of calcareous arid soils. 72 soil samples were collected from rural areas throughout north-west Syria, covering most of its agro-climatic zones and soil types. Soil water content at eight different matric potentials and 11 chemical and physical soil properties were determined. We first found that when destroying carbonates in determining particle size distribution, no significant correlations were found with the water retention points, whereas good correlations were observed when carbonates were not removed and considered as part of the soil's mineralogy. Four principal components (PC) explained 77% of the variation in the data set. Three tested soil-water contents (at -1, -33 and -1500 kPa) were highly linked to PC1 which was correlated to plastic limit, texture, soil carbonate content, and specific surface area. In addition, soil-water content at -1 kPa was also linked to PC4 which is correlated to bulk density. PC2 and PC3, related to gravel, organic matter and hygroscopic water, only explained a negligible amount of variation of soil water content. When setting up predictive functions for the eight water retention points, the support vector machines approach performed significantly better as compared to artificial neural networks and multiple linear regression, when using traditional input such as texture, organic carbon and bulk density. When using the plastic limit instead of organic carbon, the predictions accuracy of the functions could still be improved. All RMSD values were below 0.04 m3 m-3, which is very low in comparison with other studies. We finally fitted mathematical expressions to the generated water retention points which were used to derive the complete hydraulic conductivity curve (including saturated hydraulic conductivity).

Khlosi, Muhammed; Douaik, Ahmed; Habib, Hassan; Gabriels, Donald; Cornelis, Wim

2014-05-01

100

Hydraulic parameter estimation by remotely-sensed top soil moisture observations with the particle filter  

NASA Astrophysics Data System (ADS)

SummaryIn a synthetic study we explore the potential of using surface soil moisture measurements obtained from different satellite platforms to retrieve soil moisture profiles and soil hydraulic properties using a sequential data assimilation procedure and a 1D mechanistic soil water model. Four different homogeneous soil types were investigated including loamy sand, loam, silt, and clayey soils. The forcing data including precipitation and potential evapotranspiration were taken from the meteorological station of Aachen (Germany). With the aid of the forward model run, a synthetic data set was designed and observations were generated. The virtual top soil moisture observations were then assimilated to update the states and hydraulic parameters of the model by means of a particle filtering data assimilation method. Our analyses include the effect of assimilation strategy, measurement frequency, accuracy in surface soil moisture measurements, and soils differing in textural and hydraulic properties. With this approach we were able to assess the value of periodic spaceborne observations of top soil moisture for soil moisture profile estimation and identify the adequate conditions (e.g. temporal resolution and measurement accuracy) for remotely sensed soil moisture data assimilation. Updating of both hydraulic parameters and state variables allowed better predictions of top soil moisture contents as compared with updating of states only. An important conclusion is that the assimilation of remotely-sensed top soil moisture for soil hydraulic parameter estimation generates a bias depending on the soil type. Results indicate that the ability of a data assimilation system to correct the soil moisture state and estimate hydraulic parameters is driven by the non linearity between soil moisture and pressure head.

Montzka, Carsten; Moradkhani, Hamid; Weihermüller, Lutz; Franssen, Harrie-Jan Hendricks; Canty, Morton; Vereecken, Harry

2011-03-01

101

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

NASA Astrophysics Data System (ADS)

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

Jorda, Helena; Koestel, John; Jarvis, Nicholas

2014-05-01

102

Effective porosity of paddy soils as an estimation of its saturated hydraulic conductivity  

Microsoft Academic Search

Soil saturated hydraulic conductivity (Ks) is an important soil physical property. Some laboratory and field methods are expensive, time consuming and labour intensive. Indirect methods such as pedo-transfer functions (PTF) are available. Effective porosity or macroporosity (Øe) is approximately equals to porosity minus volumetric soil water content at the field capacity. According to Kozeny–Carman equation, Ks could be evaluated using

W Aimrun; M. S. M Amin; S. M Eltaib

2004-01-01

103

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

USGS Publications Warehouse

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

Simunek, J.; Nimmo, J. R.

2005-01-01

104

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

Microsoft Academic Search

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

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

2001-01-01

105

Application and assessment of a multiscale data integration method to saturated hydraulic conductivity in soil  

Microsoft Academic Search

Saturated hydraulic conductivity (Ks) is one of the most important physical properties of the soil. Inherent spatial variability of soil properties makes it necessary to obtain sufficient and reliable Ks in order to reduce the uncertainty in hydrological modeling. In this study, we employ a Bayesian hierarchical modeling framework combined with upscaling techniques and an efficient adaptive Markov Chain Monte

Na Li; Li Ren

2010-01-01

106

Unsaturated hydraulic conductivity of two compacted barrier soils  

Microsoft Academic Search

Unsaturated hydraulic conductivities were measured in the laboratory and the field for two compacted fine-grained soils used as barrier layers in landfill final covers. The instantaneous profile method was used for the laboratory and field measurements. Results of the tests show that similar unsaturated hydraulic conductivities exist in the laboratory and field for both soils. Furthermore, results of laboratory tests

J. S. Meerdink; C. H. Benson; M. V. Khire

1996-01-01

107

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

NASA Astrophysics Data System (ADS)

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

Yu, Kailiang; D'Odorico, Paolo

2014-04-01

108

Observations and Analysis of dynamic non equilibrium effects on soil hydraulic parameters  

NASA Astrophysics Data System (ADS)

In the past years, many scientists have observed dynamic non equilibrium effects on water flow in unsaturated soil where the Richard's equation fails to express the relationship between water content and hydraulic potential in the unsaturated zone. Until now, traditional techniques for determining soil hydraulic parameters have been used involving stepwise equilibrium imbibition and drainage experiments. More recently, optimization of the parameters describing the soil hydraulic functions in a transient outflow experiment using conventional methods have proved to be promising to derive soil hydraulic parameters but the estimates from one step outflow experiments using only cumulative outflow data in the objective function are often unreliable and non-unique. This work is an attempt to calculate the soil hydraulic properties using multi step outflow experiment data with different soil samples from Little Washita watershed, Oklahoma. The new dual fraction model (Diamantopolous et. al., 2012) in which water flow is treated as two fractions, one fraction with water in equilibrium with the pressure head whereas water in the second fraction as in non-equilibrium, has been used to ascertain the soil hydraulic parameters. Genetic Algorithm (GA) has been used to optimize the inverse solution of soil hydraulic parameters and to estimate uncertainties of calculated parameters using multi-populations within GA and by considering data and modeling errors. The authors aim to use the present work to be a stepping stone for calculation of dynamic non-equilibrium effects on soil hydraulic parameters estimation on greater (field) scale. The concern about dynamic non equilibrium effect on larger scale is still unanswered satisfactorily, because of conflicting hypothesized reasons such as: 1. Air entrapment is not expected to occur under natural drainage conditions, 2. erratic change in pressure at the system boundary unlike MSO experiments differ from that occurring in natural conditions. Simulated soil moisture values will be validated against observed air borne remotely sensed data soil moisture data.

Rana, S.; Mohanty, B.

2013-12-01

109

OVERCOMING THE LIMITATIONS OF IN SITU BIOREMEDIATION IN LOW PERMEABILITY SOILS THROUGH HYDRAULIC SOIL FRACTURING  

Microsoft Academic Search

Hydraulic Soil Fracturing is a process that is used to enhance the in situ remediation of contaminants present in low permeability soils (i.e. soils with a hydraulic conductivity of less than 10-6 m\\/s). Soil fracturing has been successfully applied since the early 1990's to accelerate site clean-ups using physical \\

Gordon H. Bures; Kent S. Sorenson; Jennifer P. Martin; Richard F. Reinke

110

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

111

Hydraulically powered soil core sampler and its application to soil density and porosity estimation  

Microsoft Academic Search

The design of a hydraulically powered soil core sampler used to collect undisturbed soil samples at different depths in the field is presented. The hydraulic actuation of the coring probe reduces the physical effort and time required by the operators. The device is constructed from a three-point hitch frame equipped with a gearbox, retractable legs, hydraulic cylinder and probe. The

Nidal H Abu-Hamdeh; Hamid F Al-Jalil

1999-01-01

112

Estimation of near-saturated hydraulic conductivity by minidisk infiltrometers for soils with wide pore-size distribution  

Microsoft Academic Search

Disk infiltrometers are widely used devices for quick and convenient measurement of soil surface hydraulic properties. In the present study, several estimation procedures, commonly used for the determination of near-saturated hydraulic conductivity from disk infiltration data, are evaluated using numerical modeling of three-dimensional axisymmetric flow below infiltrometer disk. The analysis is performed for a set of soils representing a wide

Michal Dohnal; Jaromir Dusek; Tomas Vogel

2010-01-01

113

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

114

FEASIBILITY OF HYDRAULIC FRACTURING OF SOILS TO IMPROVE REMEDIAL ACTIONS  

EPA Science Inventory

Hydraulic fracturing, a technique commonly used to increase the yields of oil wells, could improve the effectiveness of several methods of in situ remediation. This project consisted of laboratory and field tests in which hydraulic fractures were created in soil. Laboratory te...

115

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...

116

Properties of Fly Ash as Hydraulic Barrier  

Microsoft Academic Search

This study examines the suitability of pozzolanic fly ash as a hydraulic barrier and the use of bentonite to enhance geotechnical properties of fly ash. The behavior of fly ash is studied not only with water but also with different pore fluids, such as acid, alkali, salts, and neutral organic fluid to assess its chemical compatibility. While some geotechnical properties

P. V. SIVAPULLAIAH; H. LAKSHMIKANTHA

2004-01-01

117

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

Microsoft Academic Search

Application of process-based water flow and solute transport models is often hampered by insufficient knowledge of soil hydraulic properties. This is certainly true for dual- or multi-porosity models that account for non-equilibrium flow of water in macropores, where the saturated ‘matrix’ hydraulic conductivity is a particularly critical parameter. Direct measurement is possible, but this is impractical for larger scale studies

N. J. Jarvis; L. Zavattaro; K. Rajkai; W. D. Reynolds; Pa Olsen; M. McGechan; M. Mecke; B. Mohanty; P. B. Leeds-Harrison; D. Jacques

2002-01-01

118

Characterizing Scale and Location-Dependent Correlation of Water Retention Parameters with Soil Physical Properties Using Wavelet Techniques  

Microsoft Academic Search

Understanding the correlation between soil hydraulic parameters and soil physical properties is a prerequisite for the prediction of soil hydraulic properties from soil physical properties. Th e objective of this study was to examine the scale- and location-dependent correlation between two water retention parameters (? and n) in the van Genuchten (1980) function and soil physical properties (sand content, bulk

Qiaosheng Shu; Zuoxin Liu; Bingcheng Si

2008-01-01

119

Examining the information content of time-lapse crosshole GPR data collected under different infiltration conditions to estimate unsaturated soil hydraulic properties  

NASA Astrophysics Data System (ADS)

Time-lapse geophysical data acquired during transient hydrological experiments are being increasingly employed to estimate subsurface hydraulic properties at the field scale. In particular, crosshole ground-penetrating radar (GPR) data, collected while water infiltrates into the subsurface either by natural or artificial means, have been demonstrated in a number of studies to contain valuable information concerning the hydraulic properties of the unsaturated zone. Previous work in this domain has considered a variety of infiltration conditions and different amounts of time-lapse GPR data in the estimation procedure. However, the particular benefits and drawbacks of these different strategies as well as the impact of a variety of key and common assumptions remain unclear. Using a Bayesian Markov-chain-Monte-Carlo stochastic inversion methodology, we examine in this paper the information content of time-lapse zero-offset-profile (ZOP) GPR traveltime data, collected under three different infiltration conditions, for the estimation of van Genuchten-Mualem (VGM) parameters in a layered subsurface medium. Specifically, we systematically analyze synthetic and field GPR data acquired under natural loading and two rates of forced infiltration, and we consider the value of incorporating different amounts of time-lapse measurements into the estimation procedure. Our results confirm that, for all infiltration scenarios considered, the ZOP GPR traveltime data contain important information about subsurface hydraulic properties as a function of depth, with forced infiltration offering the greatest potential for VGM parameter refinement because of the higher stressing of the hydrological system. Considering greater amounts of time-lapse data in the inversion procedure is also found to help refine VGM parameter estimates. Quite importantly, however, inconsistencies observed in the field results point to the strong possibility that posterior uncertainties are being influenced by model structural errors, which in turn underlines the fundamental importance of a systematic analysis of such errors in future related studies.

Scholer, M.; Irving, J.; Looms, M. C.; Nielsen, L.; Holliger, K.

2013-04-01

120

Functional Relationships among Soil-air Permeability, Soil-gas Diffusivity, and Saturated Hydraulic Conductivity in Undisturbed Soils  

Microsoft Academic Search

Soil-pore geometric parameters including size distribution, total and air-filled porosity, pore tortuosity and connectivity strongly influence water and air flow in soils, and characterize soil-water and soil-gas transport parameters such as saturated hydraulic conductivity, soil-air permeability and soil-gas diffusivity. This study investigated functional relationships among the soil-pore dependent physical parameters in undisturbed soils and developed predictive expressions for soil-air permeability

K. Kawamoto; P. Moldrup; P. Schjønning; B. V. Iversen; T. Komatsu

2005-01-01

121

Hydraulic conductivity of compacted soils controlled by microbial activity.  

PubMed

The hydraulic conductivity defines the displacement of liquids inside porous media and affects the fate and transport of contaminants in the environment. In this research the influence of microbial growth and decay inside soil pores on hydraulic conductivity is analysed. Long-term tests performed in silt-bentonite mixtures permeated with distilled water and a nutrients solution demonstrated that hydraulic conductivity of compacted silt-bentonite samples decreases with time of permeation as a bioclogging mechanism develops. The injection of antibiotics and antifungals in the specimens produces a rebound in the hydraulic conductivity associated with the decay of microbial activity. These results show that biomediated reactions can be used to control the flow rate through compacted soil liners. PMID:24956782

Glatstein, Daniel Alejandro; Francisca, Franco Matías

2014-08-01

122

Estimating sphagnum peat hydraulic properties from laboratory evaporation experiments  

NASA Astrophysics Data System (ADS)

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

Weber, Tobias K. D.; Durner, Wolfgang

2013-04-01

123

Soil Taxonomy and Soil Properties.  

National Technical Information Service (NTIS)

The 16 papers in this report deal with the following areas: soil taxonomy; an overview; diagnostic soil horizons in soil taxonomy; soil moisture and temperature regimes in soil taxonomy; particle size and mineralogy in soil taxonomy; soil series and soil ...

1977-01-01

124

Data Acquisition System for Steady-State Hydraulic Soil Conductivity Measurements  

Microsoft Academic Search

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

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

2009-01-01

125

Spatial Distributions of Soil Surface-Layer Saturated Hydraulic Conductivity and Controlling Factors on Dam Farmlands  

Microsoft Academic Search

Saturated hydraulic conductivity (Ks) is a critical soil property affecting water flow and solute transport. In the Loess Plateau of China, sloping farmlands\\u000a have been increasingly replaced by dam farmlands to achieve higher crop yields and more importantly to control soil erosions.\\u000a It is necessary to understand the spatial pattern of near-surface K\\u000a \\u000a S\\u000a on those newly formed dam farmlands,

Peipei Zhao; Mingan Shao; Tiejun Wang

2010-01-01

126

In-situ LIF Analysis of Biological and Petroleum-based Hydraulic Oils on Soil  

PubMed Central

Absorption and fluorescence properties of 4 hydraulic oils (3 biological and 1 petroleum-based) were investigated. In-situ LIF (laser-induced fluorescence) analysis of the oils on a brown sandy loam soil was performed. With calibration, quantitative detection was achieved. Estimated limits of detection were below ca. 500 mg/kg for the petroleum-based oil and ca. 2000 mg/kg for one biological oil. A semi-quantitative classification scheme is proposed for monitoring of the biological oils. This approach was applied to investigate the migration of a biological oil in soil-containing compartments, namely a soil column and a soil bed.

Lemke, Matthias; Fernandez-Trujillo, Rebeca; Lohmannsroben, Hans-Gerd

2005-01-01

127

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

SciTech Connect

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

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

2011-01-01

128

Development of a Hydraulic-driven Soil Penetrometer for Measuring Soil Compaction in Field Conditions  

NASA Astrophysics Data System (ADS)

Soil compaction is an important physical limiting factor for root emergence and the growth of plants. Therefore it is essential to control soil compaction, which is normally caused by heavy traffic in fields during the growing season. Soil compaction in fields is usually measured by using standard soil cone penetrometers, which can be of several different types according to their design. Most of the time, especially in heavy soil conditions, measuring soil compaction with a standard hand penetrometer produces measurement errors if the cone of the penetrometer cannot be pushed into the soil at a standard rate. Obtaining data with hand penetrometers is also difficult and takes a long time and effort. For this reason, a three-point hitch-mounted and hydraulic-driven soil cone penetrometer has been designed in order to reduce time and effort and to reduce possible measurement errors in the sampling of soil compaction data for research purposes. The hydraulic penetrometer is mounted on the three-point hitch and a hydraulic piston pushes the standard penetrometer cone into the soil at a constant speed. Forces acting on the cone base are recorded with a computer-based 16-bit data acquisition system composed of a load cell, a portable computer, signal amplification and necessary control software for the sampling. As a conclusion, the designed and constructed three-point hitch-mounted hydraulic-driven standard soil cone penetrometer provides with quick and very accurate measurements about soil compaction in clay soil in heavy conditions.

Tekin, Yucel; Okursoy, Rasim

129

Soil Properties and Geomorphology  

NSDL National Science Digital Library

To prepare for this exercise, the students have been lectured on soil formation and on a field trip, described a simple soil within loess. Here, the students use data collected from a chronosequence to compare the relative age and amount of soil formation on a series of fluvial terraces. The students are to insert the data into a graphic program and generate specific graphs of soil properties. The students then interpret the amount of soil formation compared to the relative age of the fluvial terraces. Finally, the students assess how the 5 soil forming factors (climate, organisms, relief, parent material, and time) influenced soil formation in this setting. Designed for a geomorphology course

Sweeney, Mark

130

FEASIBILITY OF HYDRAULIC FRACTURING OF SOILS TO IMPROVE REMEDIAL ACTIONS  

EPA Science Inventory

Hydraulic fracturing, a method of increasing fluid flow within the subsurface, should improve the effectiveness of several remedial techniques, including pump and treat, vapor extraction, bio-remediation, and soil-flushing. he technique is widely used to increase the yields of oi...

131

Applications of Hydraulic Properties Models on Microscopic Flow in Unsaturated Porous Media  

Microsoft Academic Search

Several existing equations for solving the non-linear soil-hydraulic properties are introduced and validated to field and laboratory measured data. Models for non-linear hydraulic properties of unsaturated porous media arise from statistical and mathematical fit through the measured data and they can be expressed in forms of unsaturated permeability versus either pressure head or volumetric moisture content. This paper presents the

T. Bunsri; M. Sivakumar; D. Hagare

2009-01-01

132

Seasonal variability of near-saturated hydraulic conductivity on cultivated soil  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

133

Influence of spatial variability of hydraulic characteristics of soils on surface parameters obtained from remote sensing data in infrared and microwaves  

NASA Technical Reports Server (NTRS)

The correct interpretation of thermal and hydraulic soil parameters infrared from remotely sensed data (thermal infrared, microwaves) implies a good understanding of the causes of their temporal and spatial variability. Given this necessity, the sensitivity of the surface variables (temperature, moisture) to the spatial variability of hydraulic soil properties is tested with a numerical model of heat and mass transfer between bare soil and atmosphere. The spatial variability of hydraulic soil properties is taken into account in terms of the scaling factor. For a given soil, the knowledge of its frequency distribution allows a stochastic use of the model. The results are treated statistically, and the part of the variability of soil surface parameters due to that of soil hydraulic properties is evaluated quantitatively.

Brunet, Y.; Vauclin, M.

1985-01-01

134

Mechanical and Hydraulic Properties of Wax-coated Sands for Sport Surfaces  

NASA Astrophysics Data System (ADS)

Natural soils such as sandy loams are being replaced by synthetic soils for various types of sport and recreational surfaces, including horseracing tracks. These synthetic soils are made of a mixture of sand, microcrystalline wax, synthetic fibers and rubber chips which optimize the mechanical and hydraulic properties of natural soils so that they drain faster after rainstorms and decrease risks of sport injuries while retaining appropriate sport performances. Silica sand, which makes up the largest fraction of synthetic soils, is hydrophyllic by nature, i.e., tends to retain water on sand grain surfaces. After rainstorms, hydrophilic surfaces retain a large amount of water, are difficult to compact, and yield uncontrollable mechanical and hydraulic properties when too moist. The addition of wax contributes to improving both mechanical and hydraulic properties of sands. Wax coats the sand grains with a thin layer, and enhances adherence between sand particles. It repels water from sand grains and influences both compaction and hydraulic properties. This study reports experimental results that help to understand the properties of wax-coated sands used in synthetic surfaces, especially the degradation of synthetic surfaces that have insufficient wax-coatings.

Bardet, J. P.; Benazza, C.; Bruchon, J. F.; Mishra, M.

2009-06-01

135

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

136

HYDRAULIC AND PHYSICAL PROPERTIES OF MCU SALTSTONE  

SciTech Connect

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

Dixon, K; Mark Phifer, M

2008-03-19

137

Alternative methods in the development of pedotransfer functions for soil hydraulic characteristics  

NASA Astrophysics Data System (ADS)

Soil hydraulic properties are needed in the modeling of water flow and solute movement in the vadose zone. Pedotransfer functions (PTFs) have received the attention of many researchers for indirect determination of hydraulic properties from basic soil properties as an alternative to direct measurement. The objective of this study was to compare the performance of cascade forward network (CFN), multiple-linear regression (MLR), and seemingly unrelated regression (SUR) methods using prediction capabilities of point and parametric PTFs developed by these methods. The point PTFs estimated field capacity (FC), permanent wilting point (PWP), available water capacity (AWC), and saturated hydraulic conductivity ( Ks) and the parametric PTFs estimated the van Genuchten retention parameters. A total of 180 soil samples was extracted from the UNSODA database and divided into two groups as 135 for the development and 45 for the validation of the PTFs. The model performances were evaluated with three statistical tools: the maximum error (ME), the model efficiency (EF), and the D index ( D) using the observed and predicted values of a given parameter. Despite the fact that the differences among the three methods in prediction accuracies of the point and parametric PTFs were not statistically significant ( p > 0.05) except ?r and ? ( p < 0.05) based on the ANOVA test, overall MLR and SUR were somewhat better than CFN in prediction of the point PTFs, whereas CFN performed better than the other two methods in prediction of the parametric PTFs. The F.F values of FC and ?r for CFN, MLR, and SUR methods were 0.705. 0.805, 0.795 and 0.356, -0.290, -0.290, respectively, which refer to the best and worst predictions. Properties ( Ks, ?r, ?) having some difficulty in prediction were better predicted by CFN and SUR methods, where these methods predict all hydraulic properties from basic soil properties simultaneously rather than individually as in MLR. This suggests that multivariate analysis using such functional relationships between hydraulic properties and basic soil properties can be utilized in developing more accurate point and parametric PTFs with less time and effort.

Merdun, H.

2010-01-01

138

Hydraulic properties of leaves from desert shrubs  

SciTech Connect

Changes in certain tissue hydraulic properties such as elasticity, capacitance, and resistance to water flow were considered as a function of leaf water content. It has been suggested in the literature that variation in such properties may be of significance during changes in leaf hydration. In addition, the author was interested in the potential role of changes in these same tissue properties for maintaining leaf water status during drought. Two shrubs occurring in the Mojave desert, mesquite and live-oak, were studied. Measurements suggest that over the range of leaf water potential from zero to turgor loss, the elastic modulus varies 5-fold, capacitance varies 2-fold, and the resistance to flow between the xylem and storage in the leaf parenchyma tissues 2 to 3-fold. A model for water flow was developed based on these and other tissue properties. This modeling approach is being used as a hypothesis-generating tool for future experimentation. Results of the modeling are discussed in the context of published speculations on the functional role of changes in properties such as elasticity for plants under water stress.

Schulte, P.J. (Univ. of Nevada, Las Vegas (United States))

1991-05-01

139

Soil water balance scenario studies using predicted soil hydraulic parameters  

NASA Astrophysics Data System (ADS)

Pedotransfer functions (PTFs) have become a topic drawing increasing interest within the field of soil and environmental research because they can provide important soil physical data at relatively low cost. Few studies, however, explore which contributions PTFs can make to land-use planning, in terms of examining the expected outcome of certain changes in soil and water management practices. This paper describes three scenario studies that show some aspects of how PTFs may help improve decision making about land management practices. We use an exploratory research approach using simulation modelling to explore the potential effect of alternative solutions in land management. We: (i) evaluate benefits and risks when irrigating a field, and the impact of soil heterogeneity; (ii) examine which changes can be expected (in terms of soil water balance and supply) if organic matter content is changed as a result of an alternative management system; (iii) evaluate the risk of leaching to deeper horizons in some soils of Hungary. Using this research approach, quantitative answers are provided to what if? type questions, allowing the distinction of trends and potential problems, which may contribute to the development of sustainable management systems.

Nemes, A.; Wösten, J. H. M.; Bouma, J.; Várallyay, G.

2006-03-01

140

Atlas of soil reflectance properties  

NASA Technical Reports Server (NTRS)

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

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

1979-01-01

141

Assessing Hydraulic Connections Across Structural Blocks, Pahute Mesa, Nevada---Interpreting Hydraulic Properties  

Microsoft Academic Search

Groundwater beneath Pahute Mesa flows through a complexly layered sequence of volcanic-rock aquifers and confining units that have been faulted into distinct structural blocks. Hydraulic properties of the rocks and structures in this aquifer system control radionuclide migration away from areas of underground nuclear testing. The degree of hydraulic connection between structural blocks greatly affects the direction and distance of

K. J. Halford; J. M. Fenelon; C. Garcia; D. S. Sweetkind

2010-01-01

142

Spatio-temporal variation of anisotropy of saturated hydraulic conductivity in a tilled sandy loam soil  

Microsoft Academic Search

Knowledge on anisotropy of saturated hydraulic conductivity can improve the understanding of transport phenomena in soil. We hypothesized that saturated hydraulic conductivity (Ks) in the upper part of the root zone of an agricultural sandy loam soil was anisotropic at different soil depths and times after tillage. Ks was measured on undisturbed 100cm3 core samples taken in the horizontal and

C. T. Petersen; A. Trautner; S. Hansen

2008-01-01

143

Relationship between the hydraulic conductivity and electric properties for investigating the alluvium aquifer  

NASA Astrophysics Data System (ADS)

In this study, to understand relationship between hydraulic conductivity and electrical properties in alluvial aquifer, some indoor experiments and field electrical surveys were conducted. Soil sampled from alluvial aquifer and various size of quartz sand particles were saturated in NaCl solution which had 100 ohm-m. Then their porosity, hydraulic conductivity, time domain induced polarization and spectral induced polarization were measured. As a result, hydraulic conductivity and resistivity of quartz sand had proportional relation but, chargeability and phase difference of it showed small value also, hydraulic conductivity did not show clear tendency. Through this experiment, it was possible to identify which quartz sand had almost no response from induced polarization survey. Moreover, for silty sand, hydraulic conductivity and resistivity had proportional relation, hydraulic conductivity and chargeability had inverse proportional relation and hydraulic conductivity and phase difference had proportional relation. Through this experiment, silty sand showed correlation between hydraulic conductivity and electrical property. When field resistivity survey was conducted at alluvial aquifer, it showed wider range of values than the values from indoor experiment. Therefore, it is difficult to estimate accurate hydraulic conductivity of alluvial aquifer by applying hydraulic conductivity-resistivity interaction formula from indoor experiment to field resistivity survey. However, through comparison between resistivity survey result and borehole data, it was acknowledged that parts with low resistivity were clayey stratum and parts with high resistivity were gravel stratum. Consequently, estimating relative hydraulic conductivity distribution was able to be determined. However, followed by result of time domain induced polarization survey, clayey sand stratum did not have high chargeability. Through this field induced polarization survey experiment, it looks difficult to estimate hydraulic conductivity distribution.

Park, Samgyu; Kim, Soodong; Hamm, Se-Yeong

2014-05-01

144

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

NASA Astrophysics Data System (ADS)

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.

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

2007-12-01

145

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

NASA Astrophysics Data System (ADS)

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.

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

2007-08-01

146

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

147

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

USGS Publications Warehouse

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.

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

2007-01-01

148

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

149

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

150

Comparison of Saturated Hydraulic Conductivity Measurement Methods for a Glacial-Till Soil  

Microsoft Academic Search

Hydraulic conductivity is the single most important hydraulic pa- rameter for flow and transport-related phenomena in soil, but the results from different measuring methods vary under different field conditions. To evaluate the performance of four in situ saturated hydraulic conductivity (K,) measuring methods, K, measurements were made at four depths (15, 30, 60, and 90 cm) and five locations on

B. P. Mohanty; R. S. Kanwar; C. J. Everts

1994-01-01

151

Modelling the effect of rock fragment on soil saturated hydraulic conductivity  

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

152

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

153

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 ...

154

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...

155

Spatial analysis of saturated hydraulic conductivity in a soil with macropores  

Microsoft Academic Search

Saturated hydraulic conductivity (KS) is an important soil hydraulic parameter for it establishes a limit on the rate of water and solute transmission through soil. However, its determination in the laboratory has been shown to be much influenced by column size. We evaluated the spatial variability of laboratory KS measurements using three different column sizes: firstly, sixty 5.1 cm long

Dirk Mallants; Binayak P. Mohanty; André Vervoort; Jan Feyen

1997-01-01

156

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

NASA Astrophysics Data System (ADS)

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.

Bauer-Gottwein, P.

2012-04-01

157

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

NSDL National Science Digital Library

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

158

Decrease in hydraulic conductivity and particle release associated with self-filtration in saturated soil columns  

Microsoft Academic Search

The dynamics of the process of self-filtration in soil columns have been evaluated for two soils with different structural cohesion (Balkuling agricultural soil and a mining residue) by carrying out experiments focusing on microscopic particle behaviour during filtration. Soil column experiments were set up to simultaneously measure changes in hydraulic gradients (?H\\/?L) along the columns and outflow particle sizes and

Oagile Dikinya; Christoph Hinz; Graham Aylmore

2008-01-01

159

Assessing Hydraulic Connections Across Structural Blocks, Pahute Mesa, Nevada—Interpreting Hydraulic Properties  

NASA Astrophysics Data System (ADS)

Groundwater beneath Pahute Mesa flows through a complexly layered sequence of volcanic-rock aquifers and confining units that have been faulted into distinct structural blocks. Hydraulic properties of the rocks and structures in this aquifer system control radionuclide migration away from areas of underground nuclear testing. The degree of hydraulic connection between structural blocks greatly affects the direction and distance of contaminant transport, but cannot be inferred reliably from geologic interpretation. Drawdown and recovery responses from multiple aquifer tests have been observed between structural blocks where pumping and observation wells were separated by almost 4 km. Hydraulic properties of aquifers, confining units, and fault structures were estimated by interpreting pumping responses from multiple aquifer tests using a single, three-dimensional hydrogeologic framework and multiple groundwater flow models. Multiple flow-models allowed grid refinement near each pumping well. Hydraulic property estimates will be refined easily because each additional aquifer test is interpreted with another independent groundwater flow model. Model fit and sensitivities from each additional model are combined with all previous model comparisons so revised hydraulic property estimates explain all aquifer-test results. Model results suggest that more than 70 percent of the aggregate transmissivity occurs in two fractured lava-flow aquifers where transmissivity exceeds 1,000 m2/d. These aquifers comprise about 20 percent of an 800-m thick sequence of saturated, volcanic rocks and thickness-averaged hydraulic conductivity ranges between 6 and 60 m/d. The underlying units are ash-flow and bedded tuffs that were differentiated in the three-dimensional hydrogeologic framework into aquifers and confining units based on degree of welding. However, these units are indistinguishable in the flow models where hydraulic conductivity estimates are about 0.5 m/d. Faults that bound structural blocks and offset the volcanic section have similarly small estimated hydraulic conductivity and do not appear to be low-permeability barriers or high-permeability fluid conduits. The similarity of hydraulic-conductivity estimates in the lower part of the volcanic section suggests that most of the permeability could be attributed to pervasive and areally extensive secondary fracturing of the emplaced units. The observed hydraulic connection between structural blocks could be explained with fault structures that had hydraulic conductivities similar to the undisturbed host rocks.

Halford, K. J.; Fenelon, J. M.; Garcia, C.; Sweetkind, D. S.

2010-12-01

160

Hydraulic properties of adsorbed water films in unsaturated porous media  

SciTech Connect

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

Tokunaga, Tetsu K.

2009-03-01

161

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

NASA Astrophysics Data System (ADS)

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

Boadu, F. K.

2002-05-01

162

Hydraulics.  

ERIC Educational Resources Information Center

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

Decker, Robert L.; Kirby, Klane

163

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

NASA Technical Reports Server (NTRS)

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

Arya, L. M. (principal investigator)

1980-01-01

164

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

PubMed

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 × 10(-10), 2.08 × 10(-9) and 6.8 × 10(-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(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(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. PMID:22980909

Hamdi, Noureddine; Srasra, Ezzeddine

2013-01-01

165

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

166

Root-induced hydraulic changes of soil matrix - an in-situ experimental study in the wetland of Poyang Lake  

NASA Astrophysics Data System (ADS)

Plant roots may change the structure of the surface soil layer and hence the groundwater flow in wetlands. Such modifications would affect the soil condition, which in turn may influence the growth of the plants and the structure of the natural vegetation community. In order to determine the relationship between the distribution of the roots and the hydraulic property of the soil matrix, we conducted a series of in-situ experiments based on falling head test at a field site in the wetland of Poyang Lake. Areas dominated by three typical plants in the wetland, Artemisia selengensis, Phalaris arundinacea and Carex tristachya, were examined. Comparisons were also made between areas with and without plants covered. The results show that the roots improved the flow conditions of soil matrix, especially for Carex tristachya, which had a great plant and root density. The volume fraction of the roots and the grain composition of the soil were also analyzed. The regression analyses show that the root density played an important role in affecting the saturated hydraulic conductivity near the surface where the soil matrix has a larger root volume fraction. Deep into soil (after 15cm from the surface), the root volume fraction decreased and the influence of the grain composition on changes of the saturated hydraulic conductivity became more significant. These results may improve the understandings of the relationship between hydrological conditions and the growth of vegetation in the wetland.

Zhao, Z.; Jin, G.; Hua, G.; Chen, B.; Tao, X.; Li, L.

2013-12-01

167

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

Microsoft Academic Search

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

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

2008-01-01

168

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

NASA Astrophysics Data System (ADS)

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

Grabowski, Ima; Kirsch, Reinhard; Scheer, Wolfgang

2014-05-01

169

Characterization of the hydraulic properties of fractures in chalk.  

PubMed

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

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

2003-01-01

170

Water Repellency, Infiltration and Water Retention Properties of Forest Soils Under Different Management Practices  

Microsoft Academic Search

For soils under both agricultural and forest use, management and tillage practice can have significant influence on the hydraulic properties. It is therefore supposed, that management practices are capable of altering surface runoff, water retention and flood- ing risk for river catchments. Soil water repellency (hydrophobicity) can adversely affect soil hydrological properties, e.g. reduce infiltration capacity and induce pref- erential

N. A. Wahl; O. Bens; B. Schäfer; R. F. Hüttl

2002-01-01

171

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

SciTech Connect

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

Faybishenko, Boris

1997-08-01

172

Hydraulics.  

ERIC Educational Resources Information Center

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

Engelbrecht, Nancy; And Others

173

Estimating saturated and unsaturated hydraulic conductivity and sorptivity coefficient in transient state in sloping lands  

Microsoft Academic Search

Double ring and tension infiltrometer are simple and suitable instruments for determining soil hydraulic conductivity and soil sorptivity coefficient. The effect of land slope on soil properties, such as saturated and unsaturated hydraulic conductivity and soil sorptivity coefficient, has been reported by various researchers. The aim of this study was to estimate soil hydraulic conductivity and soil sorptivity coefficient values

Majid Raoof; Ali A. Sadraddini; Amir H. Nazemi; Safar Marofi

2009-01-01

174

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...

175

Evolution of unsaturated hydraulic conductivity of aggregated soils due to compressive forces  

Microsoft Academic Search

Prediction of water flow and transport processes in soils susceptible to structural alteration such as compaction of tilled agricultural lands or newly constructed landfills rely on accurate description of changes in soil unsaturated hydraulic conductivity. Recent studies have documented the critical impact of aggregate contact characteristics on water flow rates and pathways in unsaturated aggregated soils. We developed an analytical

M. Berli; A. Carminati; T. A. Ghezzehei; D. Or

2008-01-01

176

Evaluation of different methods for the prediction of saturated hydraulic conductivity in tilled and untilled soils  

Microsoft Academic Search

The larger the bulk density of the soil, the smaller the saturated hydraulic conductivity (Ks), however, the relationship between Ks and dry bulk density for tilled and untilled conditions is different. Ks is lower in tilled soil than in untilled soil with the same texture at the same bulk density. The purpose of this study was to compare different models

Ayatt Allah Rahimi; Ali Reza Sepaskhah; Seyed Hamid Ahmadi

2011-01-01

177

Probability distributions for hydraulic conductivity of compacted soil liners  

Microsoft Academic Search

This paper describes an analysis of hydraulic conductivity data collected from 57 landfill liners and covers throughout North America. Statistical characteristics of the data are summarized, and goodness-of-fit analyses are performed on each set to determine a distributional form that can be used to describe spatial variability of hydraulic conductivity. The statistics of hydraulic conductivity are shown to vary widely.

Craig H. Benson

1993-01-01

178

Impact of soil properties for European climate simulations  

NASA Astrophysics Data System (ADS)

Soil properties have a strong influence on the terrestrial water cycle, in particular by influencing soil water distribution and dynamics. This in turn affects evapotranspiration from the land to the atmosphere and thus climate conditions. While many studies have looked at the climatic influence of vegetation characteristics/land cover change, fewer investigated the importance of soil properties for climate, although soil properties can also be indirectly altered by land use changes. In this study, we investigate the influence of soil properties on the European climate using a regional climate model. First, two simulations using two different soil maps are investigated: the soil map of the world from the Food and Agricultural Organization (FAO) and the European Soil Database (ESDB) from the European Commission Joint Research Center (JRC). These simulations highlight the importance of the specified soil texture in summer, with differences of up to 2°C in mean 2-meter temperature and 20% in precipitation due to changes in the partitioning of energy at the land surface into sensible and latent heat flux. In an additional set of experiments, we modify different sets of soil physical parameters to evaluate their relative importance. Hydraulic diffusivity as well as field capacity and plant wilting point are shown to play an important role, unlike hydraulic conductivity. We highlight the importance of the vertical profile of soil moisture for evapotranspiration as it impacts soil moisture dynamics. Our study highlights the importance of soil texture and related parameters for climate simulations. Given the uncertainty associated with the geographical distribution of soil texture, efforts to improve existing databases and their integration in climate and hydrological models are needed. Tackling unresolved issues in land-surface modeling related to the high variability of soil parameters, both spatially and within a soil textural class, would benefit a large community and improve the representation of land-atmosphere feedbacks.

Guillod, B. P.; Davin, E. L.; Kündig, C.; Smiatek, G.; Seneviratne, S. I.

2012-04-01

179

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

NASA Astrophysics Data System (ADS)

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.

Fér, Miroslav; Kodešová, Radka

2012-10-01

180

LIMITING DRILLING SLURRY PRESSURES TO CONTROL HYDRAULIC FRACTURING DURING HDD THROUGH PURELY COHESIVE SOIL  

Microsoft Academic Search

Hydraulic fracturing is a problem associated with Horizontal Directional Drilling that is still inadequately understood and can result in serious consequences. During insertion of utility conduits and other buried pipe infrastructure, drilling slurry is used to stabilize the soil around the excavation zone prior to pulling the new pipeline into place. Hydraulic fracturing occurs when the drilling slurry flows through

Matthew J. Kennedy; Graeme D. Skinner; Ian D. Moore

181

The effect of microorganisms, salinity and turbidity on hydraulic conductivity of irrigation channel soil  

Microsoft Academic Search

The introduction of polysaccharide producing benthic algae and bacteria could provide a low cost technique for seepage control in irrigation channels. The ability of algae and bacteria to produce polysaccharides proved to be successful in reducing the hydraulic conductivity of irrigation channel soil. Hydraulic conductivity was reduced to less than 22% of its original value within a month of inoculating

S. R. Ragusa; D. S. Zoysa; P. Rengasamy

1994-01-01

182

Effects of model layer simplification using composite hydraulic properties  

USGS Publications Warehouse

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

Sepulveda, Nicasio; Kuniansky, Eve L.

2010-01-01

183

Coevolution of hydraulic, soil and vegetation processes in estuarine wetlands  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

184

Estimating the Hydraulic Conductivity of Glacial Tills From Soil Index Tests  

Microsoft Academic Search

The most important parameter in any groundwater flow or contaminant transport problem is hydraulic conductivity (K). However, for fine-grained soils, the measurement of hydraulic conductivity (K) can be expensive and time-consuming. Previous attempts at estimating K for fine-grained soils have been marginally successful. In this study, 23 glacial till were sampled at seven sites in McLean County, Illinois. The samples

S. Boateng; J. B. Lowery

2002-01-01

185

Electrical fields and soil properties  

Microsoft Academic Search

The electrical fields in the surface of soils appear as many different kinds. Methods of self- potential (SP), electrical profiling (EP), vertical electrical sounding (VES), and non-contact electromagnetic profiling (NEP) was used to measure the electrical properties of basic soil types, such as Spodosols, Alfisols, Histosols, Mollisols, and Aridisols (USA Soil Classification) of Russia in situ. The density of mobile

POZDNYAKOV Anatoly; POZDNYAKOVA Larisa

186

Saturated hydraulic conductivity of a volcanic ash soil affected by repulsive potential energy in a multivalent anionic system  

Microsoft Academic Search

Acid rain is supposed to influence soil structures, because soils have pH-dependent charges. The adverse effects of acid rain on soils must be assessed. Although repulsive potential energy among soil clay particles generates swelling and dispersion, thereby changing the soil’s hydraulic conductivity, the relationship between hydraulic conductivity and repulsive potential energy has not been evaluated. Moreover, research into repulsive potential

Munehide Ishiguro; Katsuya Nakaishi; Tomo Nakajima

2003-01-01

187

Kriging analysis of soil properties  

Microsoft Academic Search

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

Gilbert C. Sigua; Wayne H. Hudnall

2008-01-01

188

Hydraulics.  

ERIC Educational Resources Information Center

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

Decker, Robert L.

189

Field evidence of a negative correlation between saturated hydraulic conductivity and soil carbon in a sandy soil  

Microsoft Academic Search

Soil organic matter (SOM) is generally assumed to be positively correlated with saturated hydraulic conductivity (KS). However, recent studies of pedotransfer functions suggest a possible negative KS-SOM relationship that still needs independent verification. Our field KS study of sandy soils in a semiarid region provides such in situ evidence of a negative KS-SOM relationship, which is nonlinear and is strongest

Tiejun Wang; David Wedin; Vitaly A. Zlotnik

2009-01-01

190

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

PubMed Central

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

Carminati, Andrea; Vetterlein, Doris

2013-01-01

191

Prediction of saturated hydraulic conductivity of compacted soils using empirical scaling factors  

Microsoft Academic Search

A new empirical-based scaling method is introduced to predict saturated hydraulic conductivity (Ks) of compacted soils. This method is an improvement of the former non-similar media concept (NSMC) model that is generalized for tilled and untilled conditions. In this method, geometric mean particle size diameter (dg), geometric standard deviation (?g) and saturated soil water content (total porosity) are successfully incorporated

Seyed Hamid Ahmadi; Ali Reza Sepaskhah

2011-01-01

192

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

Microsoft Academic Search

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 (Kbiozone) under variably saturated conditions for 29 wastewater infiltration test cells installed in a sandy loam field soil. Test cells employed two loading rates (4

Johnathan R. Bumgarner; John E. McCray

2007-01-01

193

Use of porosity to estimate hydraulic properties of volcanic tuffs  

USGS Publications Warehouse

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

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

2003-01-01

194

Water retention, hydraulic conductivity of hydrophilic polymers in sandy soil as affected by temperature and water quality  

NASA Astrophysics Data System (ADS)

SummaryHydrophilic polymers can swell by absorbing huge volumes of water or aqueous solutions. This property has led to many practical applications of these new materials, particularly in arid regions for improving water retention in sandy soils and the water supply to plants grown on them. The effects of two hydrophilic polymers, carboxymethylcellulose (RF) and isopropyl acrylamide (BF) on the water holding capacity and saturated hydraulic conductivity ( KS) of a sandy soil at varying soil temperature and water quality were evaluated. The RF was less efficient in absorbing water than BF, but the efficiency of BF in retaining water was negatively affected by its thermo-sensitivity and the quality of water. The temperature dependence of the water absorption was not clear for the soils treated with RF, whereas, the efficiency of BF treatment in absorbing water decreased significantly ( P < 0.05) with increasing soil temperature. The dependence of the KS on soil temperature differed with the type of hydrophilic polymer used. The KS of the control soil remained nearly constant as the soil temperature increased. The KS of the BF treated soil increased significantly ( P < 0.05) and linearly with increasing soil temperature, while that of soil treated with RF showed a quadratic response. The soil-absorbent mixtures exhibited different water retention characteristics under different soil temperature conditions. The increase in soil temperature did not affect the water retention characteristics curve of the control. The effect of soil temperature on the water potential curve of the soil treated with RF was not clear particularly when the temperature increased from 25 to 35 °C. The water potential curve for soil-BF mixtures showed that the water content value at field capacity shifted from 0.21 to 0.10 cm 3 cm -3 for 0.1% and from 0.27 to 0.12 cm 3 cm -3 for 0.2%, as the soil temperature increased from 15 to 35 °C. This implies that the soil-BF absorbent mixtures would release some moisture as the soil temperature would increase from 15 to 35 °C, and this water could be lost by percolation or taken up by plant. It was found that available water content increased up to four times with RF as compared to control soil whereas it increased up to five times with BF treatment. At high temperature, the difference was much reduced except for RF at 0.2%. This understanding of the characteristics of the absorbents and the interactions among absorbents, soil, and temperature would be of help in water management in sandy soil.

Andry, H.; Yamamoto, T.; Irie, T.; Moritani, S.; Inoue, M.; Fujiyama, H.

2009-06-01

195

Geoelectrical evaluation of soil properties  

NASA Astrophysics Data System (ADS)

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.

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

2009-04-01

196

Identifying unsaturated soil hydraulic parameters using integrated hydrogeophysical inversion approach on time-lapse ground-penetrating radar data  

NASA Astrophysics Data System (ADS)

Recently, ground-penetrating radar (GPR) has proven to have a great potential for high resolution, non-invasive mapping of the soil hydrogeophysical properties at the scale of interest. Common GPR techniques are usually based on ray-based travel time or reflection analyses to retrieve soil dielectric permittivity, which is strongly correlated to soil water content. These methods suffer, however, from two major limitations. First, only a part of the information in the GPR signal is considered (e.g., propagation time). Second, the forward model describing the radar data is subject to relatively strong simplifications with respect to electromagnetic wave propagation phenomena. These limitations typically results in errors in the reconstructed water content images and, moreover, this does not permit to exploit all information contained in the radar data. We explored an alternative method by using full-waveform hydrogeophysical inversion of time-lapse, proximal GPR data to remotely estimate the unsaturated soil hydraulic properties. The radar system is based on international standard vector network analyzer technology and a full-waveform model is used to describe wave propagation in the antenna-air-soil system, including antenna-soil interactions. A hydrodynamic model is used to constrain the inverse electromagnetic problem in reconstructing continuous vertical water content profiles. In that case the estimated parameters reduce to the soil hydraulic properties, thereby strongly reducing the dimensionality of the inverse problem. In this study, we present an application of the proposed method to a data set collected in a field experiment. The GPR model involves a full-waveform frequency-domain solution of Maxwell's equations for wave propagation in three-dimensional multilayered media. The hydrodynamic model used in this work is based on a one-dimensional solution of Richards equation and the hydrological simulator HYDRUS 1-D was used with a single- and dual-porosity model. To monitor the soil water content dynamics, time-lapse GPR and time domain reflectometry (TDR) measurements were performed, whereby only GPR data was used in the inversion. Significant effects of water dynamics were observed in the time-lapse GPR data and in particular precipitation and evaporation events were clearly visible. The dual porosity model provided better results compared to the single porosity model for describing the soil water dynamics, which is supported by field observations of macropores. Furthermore, the GPR derived water content profiles reconstructed from the integrated hydrogeophysical inversion were in good agreement with TDR observations. These results suggest that the proposed method is promising for non-invasive characterization of the shallow subsurface hydraulic properties and monitoring water dynamics at the field scale.

Jadoon, K. Z.; Weihermüller, L.; Scharnagl, B.; Kowalsky, M. B.; Bechtold, M.; Hubbard, S. S.; Vereecken, H.; Lambot, S.

2012-04-01

197

Artifi cial Neural Network Estimation of Saturated Hydraulic Conductivity  

Microsoft Academic Search

Soil data serve as an important initialization parameter for hydro-ecological and climatological modeling of water and chemical movement, heat transfer, or land-use change. Most soil hydraulic properties are diffi cult to measure and therefore have to be estimated in most cases. Effi cient methods for estimating soil hydraulic properties are lacking for tropical soils. This study exam- ines and uses

W. A. Agyare; S. J. Park; P. L. G. Vlek

2007-01-01

198

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

PubMed

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

Bumgarner, Johnathan R; McCray, John E

2007-06-01

199

Estimation of evaporation fluxes and soil hydraulic parameters by combining an Ensemble Kalman Filter with an inversion  

NASA Astrophysics Data System (ADS)

Hydrologic modeling of unsaturated soils faces the challenge of uncertainties in the hydraulic states, the measurements, the applied initial and boundary conditions and in the description of the mathematical model itself. To combine the available but incomplete information into a consistent model, data assimilation techniques, such as the Ensemble Kalman Filter (EnKF) introduced by Evensen [1994], found increasing popularity because of their ability to assess both the hydraulic states and the material properties simultaneoulsy, accounting for these uncertainties. Especially the determination of the evaporation from the soil surface is highly inaccurate. Thus we investigate the suitability of the EnKF to estimate the evaporative boundary forcing on the basis of a subsurface Time Domain Reflectometry (TDR) time series. In this study we use the software muphi (Ippisch et al. [2006]) to solve the Richards equation in a 1D soil profile. The EnKF is applied for the state estimation of the water content. Additionally, the information gained during the analysis step of the EnKF is used to correct the evaporation. In combination with an inversion using fitphi (Ippisch et al. [2006]) for parameter estimation, evaporation and parameters are improved in an iterative way. We demonstrated the successful operation of the algorithm on a synthetic test case with water contents measured in different depths. We also showed that the uniqueness of the parameter set describing the observations depends on the width of the hydraulic states measured.

Bauser, Hannes; Jaumann, Stefan; Roth, Kurt

2014-05-01

200

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

201

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

202

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

NASA Astrophysics Data System (ADS)

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.

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

2012-10-01

203

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.

2011-01-03

204

Variability of matric potential measurements in evaporation experiments and its influence on the derived hydraulic properties  

NASA Astrophysics Data System (ADS)

The simplified evaporation method according to Schindler (1980) is an attractive method for determining hydraulic properties (retention curve and the unsaturated hydraulic conductivity) of a soil sample. In this method, a saturated sample is subject to evaporation, and the temporal course of matric potentials in the core is related to its water content loss by evaporation. Measurement and analysis are automated in the form of the commercially available product HYPROP© (UMS GmbH, Munich). The method and its implementation in the HYPROP system have shown to give accurate and reliable results with a minimum of effort and time required. In the HYPROP system, matric potentials are recorded in two planes of a soil sample by vertically installed tensiometers. The aim of this study was to experimentally investigate how representative and robust the matric potential readings at individual horizontal locations within a depth layer are, and how possible differences in matric potentials at different positions within a depth layer affect the calculated hydraulic soil properties. An additional aim was to verify whether vertically installed tensiometers give identical results to the traditionally horizontally installed tensiometers. The investigations took place in a system called BIG-HYPROP. In principle, it follows the same setup as the standard HYPROP system, but differs with respect to the soil sample size and the number of tensiometers. Whereas standard HYPROP cores are 5 cm high and 8 cm wide (250 cm³), BIG-HYPROP cores have a diameter of 24.5 cm and a height of 10 cm (4714 cm³). Five pairs of tensiometers were positioned in depths of 2.5 cm and 7.5 cm, three of them aligned vertically, and two horizontally. Additionally, temperature was measured at the bottom and in the depths 2 cm, 4 cm, 6 cm, 8 cm as well as directly at the surface. The scatter of the measured matric potentials during stage-1 evaporation was found to be very small (cv <3%). For sand, the scattering significantly increased during the transition from stage-1 to stage-2 evaporation (t = 30 h), reaching its maximum at the end of the measurement (cv = 6% to 8%). Despite differences in the tensiometer readings, the calculated hydraulic functions are very similar and associated only with very small uncertainties. The horizontally and vertically aligned tensiometers showed no systematic differences. We conclude that matric potentials measured with individual tensiometers can be reliably regarded as representative for the measurement plane. The increasing scattering of the upper tensiometers during stage-2 evaporation had a negligible effect on the identified hydraulic functions. The orientation of the tensiometers had no influence on the measured values.

Spieckermann, Mathias; Scharnagl, Benedikt; Pertassek, Thomas; von Unold, Georg; Durner, Wolfgang

2014-05-01

205

Relationships between soil erosion risk, soil use and soil properties in Mediterranean areas. A comparative study of three typical sceneries  

NASA Astrophysics Data System (ADS)

Generally, literature shows that the high variability of rainfall-induced soil erosion is related to climatic differences, relief, soil properties and land use. Very different runoff rates and soil loss values have been reported in Mediterranean cropped soils depending on soil management practices, but also in soils under natural vegetation types. OBJECTIVES The aim of this research is to study the relationships between soil erosion risk, soil use and soil properties in three typical Mediterranean areas from southern Spain: olive groves under conventional tillage, minimum tillage and no-till practices, and soils under natural vegetation. METHODS Rainfall simulation experiments have been carried out in order to assess the relationship between soil erosion risk, land use, soil management and soil properties in olive-cropped soils under different types of management and soils under natural vegetation type from Mediterranean areas in southern Spain RESULTS Results show that mean runoff rates decrease from 35% in olive grove soils under conventional tillage to 25% in olive (Olea europaea) grove soils with minimum tillage or no-till practices, and slightly over 22% in soils under natural vegetation. Moreover, considering the different vegetation types, runoff rates vary in a wide range, although runoff rates from soils under holm oak (Quercus rotundifolia), 25.70%, and marginal olive groves , 25.31%, are not significantly different. Results from soils under natural vegetation show that the properties and nature of the organic residues play a role in runoff characteristics, as runoff rates above 50% were observed in less than 10% of the rainfall simulations performed on soils with a organic layer. In contrast, more than half of runoff rates from bare soils reached or surpassed 50%. Quantitatively, average values for runoff water losses increase up to 2.5 times in unprotected soils. This is a key issue in the study area, where mean annual rainfall is above 600 mm. Regarding soil properties, the analysis shows that organic matter from soils under minimum tillage or no-till is strongly related with runoff, the amount of sediments in runoff and soil loss. In soils from olive groves, the amount of sediments in runoff was significantly related to soil pH. Moreover, for olive-cropped soils under conventional tillage, soil loss is strongly related with clayey texture, which is characteristic of these soils. Concerning this, the relationship between soil loss and coarse sand contents is highly significant, and shows that medium-sized soil particles are most prone to detachment and transport by runoff. Thus, the average content of these fractions in soils under conventional management is more than two times that from olive groves under minimal or no tillage, which are more coarsely textured. In fine-textured soils, hydraulic conductivity is reduced, thus increasing soil erosion risk. In addition, in sandy and silty soils with low clay content, infiltration rates are high even when soil sealing is observed. At the scale of this experiment, runoff generation and soil erosion risk decrease significantly in areas under natural vegetation, with lower clay contents

Gil, Juan; Priego-Navas, Mercedes; Zavala, Lorena M.; Jordán, Antonio

2013-04-01

206

Properties of two tropical soils in relation to the transport of radionuclides in the rhizosphere.  

PubMed

The uptake of radionuclides by commercial crops is being studied at two sites, Blain and Tippera, in a research farm in the Northern Territory, Australia. Studies have been performed to characterise the properties of the two soils, particularly the hydraulic properties that are considered to significantly influence the transport and plant uptake of these radionuclides in the soils The Blain soil, a sandy loam, has been categorised as SM according to the Unified Soil Classification System. Quartz is the dominant mineral for the Blain soil. The Tippera soil, a kaolinitic clayey loam has been categorised as CL. Chemical analysis results were consistent with these findings. The saturated hydraulic conductivity values were of the order of 10(-4) cm/s for the Blain soil. These values were greater by 3-4 orders of magnitude than those for the Tippera soils. The results obtained from the hydraulic property measurements were used to estimate the unsaturated hydraulic properties. A bimodal description based on van Genuchten-type partial saturation functions was used for the estimation. The estimation was qualitatively consistent with the soil types. PMID:15245852

Itakura, Takashi; Kuo, Eugenia Y; Twining, John R

2004-01-01

207

Soil Physical Properties Modulate the Effects of Climate Variability on Aboveground Productivity in a Semiarid Rangeland  

NASA Astrophysics Data System (ADS)

Accurate characterization of soil-water variability and its relation to ecosystem primary productivity are critical to understanding ecosystem response to climate change. We hypothesized that soil development modulates climate variability and controls primary productivity through control of soil-water availability, residence time, and temporal variation. This hypothesis was tested in a semiarid rangeland in the US Southwest by coupling a high temporal resolution meteorological and soil-water dataset from Holocene and Pleistocene aged soils with remotely sensed metrics of aboveground productivity. Holocene and Pleistocene soils varied significantly in soil physical properties such as clay and organic matter content and bulk density. A multi-year time series of Normalized Difference Vegetation Index (NDVI) data indicated distinct patterns in aboveground production by landscape age; both the start of growing season and peak NDVI values of Pleistocene soils lagged behind Holocene soils. In addition, Pleistocene soil aboveground biomass productivity was roughly 75% that of Holocene soils. The link between soil-water and NDVI was carried out using simulations of root water uptake in HYDRUS-1D. Soil hydraulic properties were generated with Rosetta and HYDRUS simulations provisionally matched to observed soil-water contents. Pleistocene soils exhibited an order of magnitude lower saturated hydraulic conductivity as well as less potential soil-water availability, relative to Holocene soils. Plant transpiration estimated from HYDRUS demonstrated a high degree of correspondence to aboveground productivity patterns observed with integrated NDVI values for both soils. Correlations (R) between NDVI and modeled transpiration data were 0.79 and 0.89 for the Pleistocene and Holocene data, respectively, indicating a very strong correspondence between NDVI and soil-water status. These data indicate that variation in aboveground productivity with landscape age may be quantitatively linked to soil hydraulic properties and soil-water dynamics.

Rasmussen, C.; Crimmins, M.; Schaap, M.; van Leeuwen, W.

2008-12-01

208

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

209

Using Soil Texture to Estimate Saturated Hydraulic Conductivity and the Impact on Rainfall-Runoff Simulations  

Microsoft Academic Search

In this paper a new set of soil texture data is used to estimate the spatial distribution of saturated hydraulic conductivity values for a small rangeland catchment. The estimates of conductivity are used to re-excite and re-evaluate a quasi-physically based rainfall-runoff model. The performance of the model is significantly reduced with conductivity estimates gleaned from soil texture data rather than

Keith Loague

1992-01-01

210

Estimating Saturated Hydraulic Conductivity In Spatially Variable Fields Using Neural Network Ensembles  

Microsoft Academic Search

Modeling contaminant and water flow through soil requires ac- curate estimates of soil hydraulic properties in field scale. Although artificial neural networks (ANNs) based pedotransfer functions (PTFs) have been successfully adopted in modeling soil hydraulic properties at larger scales (national, continental, and intercontinental), the utility of ANNs in modeling saturated hydraulic conductivity (Ks) at a smaller (field)scale has rarelybeenreported. Hence,

Kamban Parasuraman; Amin Elshorbagy; Bing Cheng Si

2006-01-01

211

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

EPA Science Inventory

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

212

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

EPA Science Inventory

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

213

Field methods for measuring hydraulic properties of peat deposits  

NASA Astrophysics Data System (ADS)

New field techniques were developed and tested to evaluate peat storativity and hydraulic conductivity in a Boreal fen. Enclosed drainage tests and pumping tests were successfully completed in the thawed peat above an impermeable frozen layer and then repeated when the peat was fully thawed. A loading test experiment constrained values of vertical hydraulic conductivity within an order of magnitude for the peat below a depth of 2 m. An inherent advantage of these tests is that volumes of undisturbed peat on the scale of cubic metres may be characterized. Storativity of the fen peat as determined by enclosed drainage tests ranged from about 1.0 at the peat surface to 0.35 at a water table depth of 0.15 m. Laboratory drainage tests of peat cores gave similar, but widely scattered results. Hydraulic conductivity near the surface was as high as 9.0 × 10-3 ms-1 determined with pumping tests and in the range of 10-6 to 10-5 ms-1 below a depth of 2 m, estimated with the loading test. Slug tests gave similar results. Pumping tests, enclosed storativity tests and loading tests are practical large-scale field tests for determining peat properties. Copyright

Hogan, J. M.; van der Kamp, G.; Barbour, S. L.; Schmidt, R.

2006-11-01

214

Estimating hydraulic conductivity of internal drainage for layered soils in situ  

NASA Astrophysics Data System (ADS)

The soil hydraulic conductivity (K function) of three layered soils cultivated at Paradys Experimental Farm, near Bloemfontein (South Africa), was determined from in situ drainage experiments and analytical models. Pre-ponded monoliths, isolated from weather and lateral drainage, were prepared in triplicate on representative sites of the Tukulu, Sepane and Swartland soil forms. The first two soils are also referred to as Cutanic Luvisols and the third as Cutanic Cambisol. Soil water content (SWC) was measured during a 1200 h drainage experiment. In addition soil physical and textural data as well as saturated hydraulic conductivity (Ks) were derived. Undisturbed soil core samples of 105 mm with a height of 77 mm from soil horizons were used to measure soil water retention curves (SWRCs). Parameterization of SWRC was through the Brooks and Corey model. Kosugi and van Genuchten models were used to determine SWRC parameters and fitted with a RMSE of less 2%. The SWRC was also used to estimate matric suctions for in situ drainage SWC following observations that laboratory and in situ SWRCs were similar at near saturation. In situ K function for horizons and the equivalent homogeneous profiles were determined. Model predictions based on SWRC overestimated horizons K function by more than three orders of magnitude. The van Genuchten-Mualem model was an exception for certain soil horizons. Overestimates were reduced by one or more orders of magnitude when inverse parameter estimation was applied directly to drainage SWC with HYDRUS-1D code. Best fits (R2 ? 0.90) were from Brooks and Corey, and van Genuchten-Mualem models. The latter also predicted the profiles' effective K function for the three soils, and the in situ based function was fitted with R2 ? 0.98 irrespective of soil type. It was concluded that the inverse parameter estimation with HYDRUS-1D improved models' K function estimates for the studied layered soils.

Mavimbela, S. S. W.; van Rensburg, L. D.

2013-11-01

215

Construction of Flexible Subterranean Hydraulic Barriers in Soil and Rock  

SciTech Connect

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

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

2008-07-01

216

Low-field NMR logging sensor for measuring hydraulic parameters of model soils  

NASA Astrophysics Data System (ADS)

SummaryKnowing the exact hydraulic parameters of soils is very important for improving water management in agriculture and for the refinement of climate models. Up to now, however, the investigation of such parameters has required applying two techniques simultaneously which is time-consuming and invasive. Thus, the objective of this current study is to present only one technique, i.e., a new non-invasive method to measure hydraulic parameters of model soils by using low-field nuclear magnetic resonance (NMR). Hereby, two model clay or sandy soils were respectively filled in a 2 m-long acetate column having an integrated PVC tube. After the soils were completely saturated with water, a low-field NMR sensor was moved up and down in the PVC tube to quantitatively measure along the whole column the initial water content of each soil sample. Thereafter, both columns were allowed to drain. Meanwhile, the NMR sensor was set at a certain depth to measure the water content of that soil slice. Once the hydraulic equilibrium was reached in each of the two columns, a final moisture profile was taken along the whole column. Three curves were subsequently generated accordingly: (1) the initial moisture profile, (2) the evolution curve of the moisture depletion at that particular depth, and (3) the final moisture profile. All three curves were then inverse analyzed using a MATLAB code over numerical data produced with the van Genuchten-Mualem model. Hereby, a set of values ( ?, n, ?r and ?s) was found for the hydraulic parameters for the soils under research. Additionally, the complete decaying NMR signal could be analyzed through Inverse Laplace Transformation and averaged on the 1/ T2 space. Through measurement of the decay in pure water, the effect on the relaxation caused by the sample could be estimated from the obtained spectra. The migration of the sample-related average <1/ T2, Sample> with decreasing saturation speaks for a enhancement of the surface relaxation as the soil dries, in concordance with results found by other authors. In conclusion, this low-field mobile NMR technique has proven itself to be a fast and a non-invasive mean to investigate the hydraulic behavior of soils and to explore microscopical aspect of the water retained in them. In the future, the sensor should allow easy soil moisture measurements on-field.

Sucre, Oscar; Pohlmeier, Andreas; Minière, Adrien; Blümich, Bernhard

2011-08-01

217

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

PubMed Central

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

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

2013-01-01

218

Can hydraulic parameters of a physically based model be identified by time series soil moisture data?  

NASA Astrophysics Data System (ADS)

To compute spatially-averaged soil moisture, groundwater recharge, evapotranspiration,interception, large scale hydrol. models require the effective param to be known at the scale of interest. Deriving effective param by upscaling point measurements require the collection of a large data set. A cost-efficient alternative is to derive the effective param by inverse modeling that consists of optimizing the parameters against the surface soil moisture from remote sensing platforms. Nevertheless the accuracy of this promising method is still being investigated. Pollacco(2008 showed by performing numerical experiments for which all the fluxes are known by using a physically based model, that there are no unique optimal hydraulic param (giving similar value of the OF and fluxes) that can be obtained. They further showed that an excellent fit can be achieved by optimizing only 2 functional hydraulic param. The non-uniqueness of the hydraulic parameters poses difficulties to compare effective parameters determined from inverse modeling with the ones obtained by upscaling point measurements. Therefore further studies are conducted to determine the validity of the results of Pollacco(2008) and to establish if the range of the feasible hydraulic parameters can be reduced. To constrain the parameter space, we used the formula deduced by (Gurracino,2007)Ks(?sat,?). Nevertheless by using the Linking Test the results shows that this equation reduced successfully the dimensionality of the problem but did not resolve the non uniqueness problem. To determine the feasibility of optimizing the hydraulic param against soil moisture,12 major soil textural groups according to Carsel&Parrish,(1988) was selected. We performed a sensitive analysis of the Root Mean Square Error(soil moisture) on recharge. The results showed that the accuracy of predicting recharge depends to a large extent on the textural groups and noton the vegetation type. The finding is that “pure” sandy soils (fast percolation) and clay soils (slow percolations) are not identifiable by inverting soil moisture. It is to be noted that these extreme soils have a small distribution worldwide. Nevertheless an experiment conducted by using a multiple OF of soil moisture and ET helped to constrain significantly the feasible parameter space of these soils. Hence, more research is required to get a more reliable estimate of actual evaporation from remote sensing. A practical result is that for soils that can be determined by inverting soil moisture requires (as described above) only 2 functional parameters (n and ?sat) are required. The other parameters ?r=0; Ks(Gurracino, 2007), & hae=106cm can remain “constant”. The value of hae=106 cm was determined by analyzing how the feasible param space of the different texture class overlap. One can compare between functional param determined from remote sensing and hydraulic param estimated from ground truth (physical param) by transforming physical parameters to functional param by using for instance SWAP(modified). Another benefit of using 2 functional hydraul param is that it enables to compare soils based on their hydrology and the functional parameters are uncorrelated, simplifying notably the task of upscaling.

Pollacco, J. A.; Mohanty, B. P.

2009-12-01

219

Lunar soil properties and soil mechanics  

NASA Technical Reports Server (NTRS)

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

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

1972-01-01

220

Multiple objective function simulator algorithm for hydraulic parameters estimation by surface soil moisture and evapotranspiration  

NASA Astrophysics Data System (ADS)

Effective hydraulic parameters can be derived from surface soil moisture, and evapotranspiration retrieved from remote sensing, by inverting the 1D Richards’ equation. Large errors in predicting the water fluxes composed of ground water recharge and soil moisture storage was found for twenty two hydroclimatic scenarios if the relative weighting between soil moisture and evapotranspiration is not well calibrated. The optimal weighting is selected in order to obtain linearity between uncertainties of retrieving the observations from remote sensing and the uncertainties of computing the water fluxes. The new method enables to constrain the Pareto trade-off curve of a multi-objective calibration. In this study we showed that the predictions of the soil hydraulic parameters for coarse texture soils exposed to dry climates can be improved by omitting the period where decoupling between surface and subsurface soil moisture occurs. Decoupling may occur when the surface moisture is in the drying phase and below a decoupling threshold. It was also found that the usage of multiple objective function was not always beneficial in improving the predictions for very wet or very dry climates. The uncertainties of predicting the water outputs are a function of the frequency distribution of soil moisture.

Pollacco, J. A.; Mohanty, B. P.

2010-12-01

221

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

PubMed

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

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

2011-10-01

222

Comparison of alternative functions to describe the near-saturated hydraulic conductivity  

Microsoft Academic Search

The estimation of soil hydraulic properties is a fundamental step for quantifying water and solute movement in the vadose zone. Tension infiltrometers have been used extensively to determine the unsaturated hydraulic conductivity (K) of soils and to examine the effects of macropores on infiltration. The near saturated hydraulic conductivity, defined as hydraulic conductivity at pressure heads (h) larger than -120

D. Ventrella; N. Losavio; M. Mastrorilli

2003-01-01

223

Derivation of Soil Moisture Retention Characteristics from Saturated Hydraulic Conductivity  

Microsoft Academic Search

Knowledge of the physics of soil water movement is crucial to the solution of many problems in watershed hydrology, for example, the prediction of runoff and infiltration following precipitation, the subsequent distribution of infiltrated water by drainage and evaporation, and estimation of the contribution of various parts of a watershed to the ground water storage. Mathematical models of hydrologic and

C. P. KUMAR; S. M. SETH

224

Hydrology and hydraulic properties of a bedded evaporite formation  

NASA Astrophysics Data System (ADS)

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

Beauheim, Richard L.; Roberts, Randall M.

2002-03-01

225

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

226

Interrelations among the soil-water retention, hydraulic conductivity, and suction-stress characteristic curves  

USGS Publications Warehouse

The three fundamental constitutive relations that describe fluid flow, strength, and deformation behavior of variably saturated soils are the soil-water retention curve (SWRC), hydraulic conductivity function (HCF), and suction-stress characteristic curve (SSCC). Until recently, the interrelations among the SWRC, HCF, and SSCC have not been well established. This work sought experimental confirmation of interrelations among these three constitutive functions. Results taken from the literature for six soils and those obtained for 11 different soils were used. Using newly established analytical relations among the SWRC, HCF, and SSCC and these test results, the authors showed that these three constitutive relations can be defined by a common set of hydromechanical parameters. The coefficient of determination for air-entry pressures determined independently using hydraulic and mechanical methods is >0.99, >0.98 for the pore size parameter, and 0.94 for the residual degree of saturation. One practical implication is that one of any of the four experiments (axis-translation, hydraulic, shear-strength, or deformation) is sufficient to quantify all three constitutive relations.

Lu, Ning; Kaya, Murat; Godt, Jonathan W.

2014-01-01

227

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

228

Hydrogen peroxide effects on root hydraulic properties and plasma membrane aquaporin regulation in Phaseolus vulgaris.  

PubMed

In the last few years, the role of reactive oxygen species as signaling molecules has emerged, and not only as damage-related roles. Here, we analyzed how root hydraulic properties were modified by different hydrogen peroxide (H2O2) concentrations applied exogenously to the root medium. Two different experimental setups were employed: Phaseolus vulgaris plants growing in hydroponic or in potted soils. In both experimental setups, we found an increase of root hydraulic conductance (L) in response to H2O2 application for the first time. Twenty millimolar was the threshold concentration of H2O2 for observing an effect on L in the soil experiment, while in the hydroponic experiment, a positive effect on L was observed at 0.25 mM H2O2. In the hydroponic experiment, a correlation between increased L and plasma membrane aquaporin amount and their root localization was observed. These findings provide new insights to study how several environmental factors modify L. PMID:19437122

Benabdellah, Karim; Ruiz-Lozano, Juan Manuel; Aroca, Ricardo

2009-08-01

229

Estimating vadose zone hydraulic properties using ground penetrating radar: The impact of prior information  

NASA Astrophysics Data System (ADS)

A number of geophysical methods, such as ground-penetrating radar (GPR), have the potential to provide valuable information on hydrological properties in the unsaturated zone. In particular, the stochastic inversion of such data within a coupled geophysical-hydrological framework may allow for the effective estimation of vadose zone hydraulic parameters and their corresponding uncertainties. A critical issue in stochastic inversion is choosing prior parameter probability distributions from which potential model configurations are drawn and tested against observed data. A well chosen prior should reflect as honestly as possible the initial state of knowledge regarding the parameters and be neither overly specific nor too conservative. In a Bayesian context, combining the prior with available data yields a posterior state of knowledge about the parameters, which can then be used statistically for predictions and risk assessment. Here we investigate the influence of prior information regarding the van Genuchten-Mualem (VGM) parameters, which describe vadose zone hydraulic properties, on the stochastic inversion of crosshole GPR data collected under steady state, natural-loading conditions. We do this using a Bayesian Markov chain Monte Carlo (MCMC) inversion approach, considering first noninformative uniform prior distributions and then more informative priors derived from soil property databases. For the informative priors, we further explore the effect of including information regarding parameter correlation. Analysis of both synthetic and field data indicates that the geophysical data alone contain valuable information regarding the VGM parameters. However, significantly better results are obtained when we combine these data with a realistic, informative prior.

Scholer, Marie; Irving, James; Binley, Andrew; Holliger, Klaus

2011-10-01

230

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

USGS Publications Warehouse

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.

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

1981-01-01

231

Evaluation of the physical properties of water treatment residue for use as a soil substitute compared with decomposed granite soil  

Microsoft Academic Search

To evaluate water treatment residue (WTR) as a soil substitute material, its physical properties were investigated and compared with decomposed granite soil (DGS). For comparison purposes, relative gas diffusivity (D\\/D0), saturated hydraulic conductivity (Ks), water retention curve, porosity and readily available water were measured for both the WTR and the DGS. The measured D\\/D0, Ks, water retention ability and porosity

Seok-Gon Park; Mizue Ohashi; Kiyoshi Kurosawa; Young-Jin Kim; Hisashi Yahata

2010-01-01

232

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

SciTech Connect

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

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

2007-02-01

233

Comparison of two methods for summarizing hydraulic conductivities of a layered soil  

NASA Astrophysics Data System (ADS)

Hydraulic conductivity data are frequently summarized using mathematical functions that quantify the relationship between water content (?) and hydraulic conductivity (K(?)). This study was done to determine the effects of the choice of the K(?) function and to determine if field data from layered profiles could be summarized using only one parameter per depth. Three K(?) functions together with a matching factor were fitted to hydraulic conductivity data from a field plot. The functions were Km(?/?m)1/?, Km[(?m-?c)/(?-?c)]1/n,and Km exp {?(?-?m)}, where ?, ?, n, Km, ?c, and ?m, are parameters to be estimated. For each function, two methods were considered. Method 1 fitted a different value to ?, ?, n, and Km for each depth while maintaining ?c at a fixed value. All hydraulic conductivity functions fit data from a Muir silt loam equally well, as evidenced by the coefficient of linearity (r2) values greater than 0.72, mean square error (MSE) values less than 0.97, and coefficient of variation (CV) values less than 50%. The fitting was accomplished using ln {K} as the dependent variable. Method 2 fitted values by depth only to Km, and all other parameters were held constant. The hydraulic conductivity functions performed equally well, with r2 values greater than 0.60, MSE values less than 1.2, and CV values of 50% or less. When some loss of precision can be tolerated, the number of parameters required to summarize data from a layered soil can be reduced.

Sisson, J. B.; Klittich, W. M.; Salem, S. B.

1988-08-01

234

Estimating saturated soil hydraulic conductivity using water retention data and neural networks  

Microsoft Academic Search

The modified Kozeny-Carman equation K{sub sat} = BΦ{sub e}n is used to relate soil saturated hydraulic conductivity K{sub sat} to effective porosity Φ{sub e}. However, different values of the coefficient B and the exponent n are found in different data sets. Their objective was to find out whether and how B and n are related to Brooks-Corey's air entry pressure

Y. A. Pachepsky; D. J. Timlin; L. R. Ahuja

1999-01-01

235

Pedo-transfer function for saturated hydraulic conductivity of lowland paddy soils  

Microsoft Academic Search

In paddy field, soil saturated hydraulic conductivity (K\\u000a s) plays as an important component in the calculation of irrigation requirement of the water balance equation and also for\\u000a irrigation efficiency. Several laboratory and field methods can be used to determine K\\u000a s. Laboratory and field determinations are usually time consuming, expensive and labour intensive. Pedo-transfer functions\\u000a (PTF) serve to translate

W. Aimrun; M. S. M. Amin

2009-01-01

236

Testing laboratory methods to determine the anisotropy of saturated hydraulic conductivity in a sandy–loam soil  

Microsoft Academic Search

Anisotropy, a (the log of the ratio of horizontal to vertical conductivity, log10(Kh\\/Kv)), of saturated soil hydraulic conductivity, Ks, affects transport processes in soil but is not routinely measured, probably because practical and validated methods are lacking. The objective of this investigation was to determine the effects of different constant-head laboratory and sampling procedures on anisotropy of saturated hydraulic conductivity

V. Bagarello; S. Sferlazza; A. Sgroi

2009-01-01

237

Laboratory Studies to Examine the Impact of Polyacrylamide (PAM) on Soil Hydraulic Conductivity  

NASA Astrophysics Data System (ADS)

Polyacrylamide (PAM) is a long-chain synthetic polymer made of the monomer acrylamide (AMD). PAM has numerous uses ranging from food processing to drilling to wastewater treatment. More recently it has been proposed as a canal sealant in the western US to improve water conservation. To support a larger field-based experimental program being implemented in Grand Junction, CO, soil column experiments are being conducted to evaluate the mechanisms of how, and to what extent, PAM reduces soil hydraulic conductivity. The goal of the experiments is to find the optimum concentration and application method of PAM that reduces hydraulic conductivity to the greatest extent. Column tests were conducted, in triplicate, using a constant head method in acrylic columns of 15 cm length and 6.4 cm diameter. An unbalanced multi-factorial design was used with experimental variables including soil type (medium silica sand, locally-derived sand, and locally-derived loam), PAM concentration (11, 22, 44, 88 kg/canal-ha), turbidity (0, 100, 350 NTU), and application method (hydrated PAM on dry soil and powdered PAM applied to water column above saturated soil). Non-crosslinked anionic PAM with a molecular weight of 12 to 24 Mg/mol was used for all experiments. Additional experiments were conducted in graduated cylinders to evaluate interactions between PAM, turbidity and water chemistry. Results of the laboratory tests will be presented and discussed in the context of water conservation in the western US.

Moran, E. A.; Young, M. H.; Yu, Z.

2005-12-01

238

Effect of soil management on some physical and chemical properties of salt-affected soil  

Microsoft Academic Search

\\u000a A field experiment was conducted at San-El-Hagar, to study the effect of gypsum application, nitrogenous and phosphatic fertilization\\u000a on some physical and chemical properties of saline alkali soils cultivated with rice.\\u000a \\u000a \\u000a The obtained results revealed that gypsum addition either with or without NP fertilizers improved the physical properties,\\u000a viz., water stable aggregates, hydraulic conductivity and mean pore diameter.\\u000a \\u000a \\u000a \\u000a Also, it

M. Wagdi Abdel Hamid; A. A. Shiha; E. E. Kaoud; S. M. Metwally

239

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

SciTech Connect

A method is described for the joint use of time-lapse ground-penetrating radar (GPR) travel times and hydrological data to estimate field-scale soil hydraulic parameters. We build upon previous work to take advantage of a wide range of cross-borehole GPR data acquisition configurations and to accommodate uncertainty in the petrophysical function, which relates soil porosity and water saturation to the effective dielectric constant. We first test the inversion methodology using synthetic examples of water injection in the vadose zone. Realistic errors in the petrophysical function result in substantial errors in soil hydraulic parameter estimates, but such errors are minimized through simultaneous estimation of petrophysical parameters. In some cases the use of a simplified GPR simulator causes systematic errors in calculated travel times; simultaneous estimation of a single correction parameter sufficiently reduces the impact of these errors. We also apply the method to the U.S. Department of Energy (DOE) Hanford site in Washington, where time-lapse GPR and neutron probe (NP) data sets were collected during an infiltration experiment. 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. These examples demonstrate that the complimentary information contained in geophysical and hydrological data can be successfully extracted in a joint inversion approach. Moreover, since the generation of tomograms is not required, the amount of GPR data required for analyses is relatively low, and difficulties inherent to tomography methods are alleviated. Finally, the approach provides a means to capture the properties and system state of heterogeneous soil, both of which are crucial for assessing and predicting subsurface flow and contaminant transport.

Kowalsky, M B.; Finsterle, Stefan A.; Peterson, John; Hubbard, Susan; Rubin, Yoram; Majer, Ernest L.; Ward, Andy L.; Gee, Glendon W.

2005-12-01

240

Relationship of Apparent Soil Electrical Conductivity to Claypan Soil Properties  

Microsoft Academic Search

tantly, subsets of indicators could be related to a specific soilfunction(KarlenandStott,1994;Brejdaetal.,2000). Understanding relationships between sensor-based measurements Indicator measurements used to assess soil quality must and soil properties related to soil quality may help in developing site- beresponsivetomanagementpracticestoobservechanges specific management. The primary objective of this research was to that might either improve or impair the soil (Karlen examine whether sensor-based apparent

W. K. Jung; N. R. Kitchen; K. A. Sudduth; R. J. Kremer; P. P. Motavalli

2005-01-01

241

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

SciTech Connect

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

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

1995-08-01

242

High-order averaging method of hydraulic conductivity for accurate soil moisture modeling  

NASA Astrophysics Data System (ADS)

Richards' equation (RE) is the most common mathematical expression for soil water movement in a porous medium. Despite advancements in numerical schemes and high-performance computing, the requirements of iterative computations and fine grids hinder further extension of the RE to multi-dimensional and large-scale applications. Averaging methods of hydraulic conductivity have been known to be one of the significant factors affecting the accuracy of numerical solutions of the RE, especially when coarse grids are used. In this study, we developed a high-order averaging method of hydraulic conductivity for accurate numerical modeling of the RE, which has a straightforward formula regardless of the soil conditions and produces high simulation accuracy when used on coarse grids. The developed method is based on the high-order upwind scheme, which is widely used for hyperbolic partial differential equations within a finite volume framework in order to prevent numerical oscillations near a discontinuity while preserving high-order accuracy. Numerical simulations of several one- and two-dimensional cases performed in the study indicate that the proposed method outperforms existing simple averaging methods and is also superior, or at least equivalent, to complex averaging methods over a wide range of soil textures, especially on coarse grids. In addition, the proposed method is straightforwardly extended to nonorthogonal grids by being combined with the coordinate transformation method and the extension is verified through multi-dimensional test cases as well as tests on a heterogeneous soil domain.

An, Hyunuk; Noh, Seong Jin

2014-08-01

243

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

NASA Astrophysics Data System (ADS)

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.

Elliot, Thomas Ross

244

Soil saturated hydraulic conductivity assessment from expert evaluation of field characteristics using an ordered logistic regression model  

Microsoft Academic Search

The knowledge of the soil saturated hydraulic conductivity (Ks) is essential for irrigation management purposes and for hydrological modelling. Several attempts have been done to estimate Ks in base of a number of soil parameters. However, a reliable enough model for qualitative Ks estimation based on the expert assessment of field characteristics had not been developed up to date. Five

Florencio Ingelmo; José Miguel de Paz; Fernando Visconti

2011-01-01

245

Communicating soil property variability in heterogeneous soil mapping units  

NASA Astrophysics Data System (ADS)

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

Farewell, Timothy

2014-05-01

246

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

USGS Publications Warehouse

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

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

1996-01-01

247

Measuring hydraulic properties of peat through inversion of pumping test data  

NASA Astrophysics Data System (ADS)

The hydraulic conductivity of peat affects flow patterns and rates that influence biogenic gas dynamics, vegetation patterns, and biomass accumulation rates in peatland ecosystems. Biogenic gasses, such as methane, trapped within the peat complicate this relationship by occluding pore space and changing the hydraulic conductivity of the peat. We have completed pumping tests at two locations, a forested bog and open lawn, within the Glacial Lake Agassiz Peatlands to characterize the hydraulic conductivity in this peatland. Traditional analysis of pumping tests provide bulk estimates of hydraulic conductivity. In contrast, the spatial distribution of hydraulic conductivity in our study area have been estimated using regularized inversion to calibrate a computer simulation with pumping test data. Computer models of pumping tests were developed using FiPy, a finite-volume modeling library. Parameter estimation software (PEST) was used to repeatedly run simulations while adjusting hydraulic properties assigned to cells within the computer model. Results from the regularized inversion of the pumping test data indicate that the hydraulic conductivity of the deeper peat at the bog and lawn sites typically ranged from 10-6 to 10-5 and 10-3 to 10-4 m/sec, respectively. Anomalous hydraulic conductivity bands were present in the deep peat and hydraulic conductivity did not systematically increase with depth. Lenses of low hydraulic conductivity peat are present in out calibrated models and may represent areas of trapped biogenic gas, but these lenses lie in regions of our computer model that are poorly constrained by the regularized inversion.

Rhoades, J.; Reeve, A. S.

2009-05-01

248

Quantifying the impact of livestock grazing on soil physical properties  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

249

A soil core sampler for paddy soils and some physical properties of the soils under waterlogged condition  

Microsoft Academic Search

IntroductionRecent investigations in soil science have shown that physical properties of paddy soils are of great importance to rice-production. There is extensive literature on the chemical property of paddy soils, but little information on the physical property of paddy soils, especially under waterlogged condition. For studying the physical property of flooded paddy soils, it is necessary to collect the soil

Keizaburo Kawaguchi; Daizo Kita; Kazutake Kyuma

1956-01-01

250

A Catalog of Vadose Zone Hydraulic Properties for the Hanford Site  

SciTech Connect

To predict contaminant release to the groundwater, it is necessary to understand the hydraulic properties of the material between the release point and the water table. Measurements of the hydraulic properties of the Hanford unsaturated sediments that buffer the water table are available from many areas of the site; however, the documentation is not well cataloged nor is it easily accessible. The purpose of this report is to identify what data is available for characterization of the unsaturated hydraulic properties at Hanford and Where these data can be found.

Freeman, Eugene J.; Khaleel, Raziuddin; Heller, Paula R.

2002-09-30

251

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

SciTech Connect

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.

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

252

Hydraulic properties of groundwater systems in the saprolite and sediments of the wheatbelt, Western Australia  

NASA Astrophysics Data System (ADS)

Hydraulic properties of deeply weathered basement rocks and variably weathered sedimentary materials were measured by pumping and slug-test methods. Results from over 200 bores in 13 catchments, and eight pumping-test sites across the eastern and central wheatbelt of Western Australia were analysed. Measurements were made in each of the major lithological units, and emphasis placed on a ubiquitous basal saprolite aquifer. Comparisons were made between alternative drilling and analytical procedures to determine the most appropriate methods of investigation. Aquifers with an average hydraulic conductivity of 0.55 m day -1 occur in variably weathered Cainozoic sediments and poorly weathered saprolite grits (0.57 m day -1). These aquifers are separated by an aquitard (0.065 m day -1) comprising the mottled and pallid zones of the deeply weathered profile. Locally higher values of hydraulic conductivity occur in the saprolite aquifer, although after prolonged periods of pumping the values decrease until they are similar to those obtained from the slug-test methods. Hydraulic conductivities measured in bores drilled with rotary auger rigs were approximately an order of magnitude lower than those measured in the same material with bores drilled by the rotary air-blast method. Wheatbelt aquifers range from predominantly unconfined (Cainozoic sediments), to confined (saprolite grit aquifer). The poorly weathered saprolite grit aquifer has moderate to high transmissivities (4-50 m 2 day -1) and is capable of producing from less than 5 to over 230 kl day -1 of ground water, which is often of a quality suitable for livestock. Yields are influenced by the variability in the permeability of isovolumetrically weathered materials from which the aquifer is derived. The overlying aquitard has a low transmissivity (< 1 m 2 day -1), especially when deeply weathered, indurated and silicified. The transmissivity of the variably weathered sedimentary materials ranges from less than 0.5 m 2 day -1 to over 10 m 2 day -1, depending on the texture of the materials and their position within the landscape. Higher transmissivity zones may occur as discrete layers of coarser textured materials. The salinity of the saprolite and sedimentary aquifers ranges from less than 2000 mgl -1 to greater than 250000 mgl -1 (total dissolved solids; TDS), depending on position within the landscape. Secondary soil salinization develops when groundwater discharge occurs from either saprolite or sedimentary aquifers.

George, Richard J.

1992-01-01

253

Effect of rock fragment addition on hydro-dispersive properties of compacted soils  

NASA Astrophysics Data System (ADS)

Compaction of agricultural soils is an increasingly challenging problem for crop production and environment. Mechanization of agricultural practices is one of the main factors inducing degradation of soil structure, especially in fragile soils with little organic matter and low shrinking-swelling capacity. Moreover, rock picking from stony soils is a routine practice to avoid tillage problems in some agricultural productions, but stone removal can significantly increase soil compaction, which lowers water infiltration rates and increases surface runoff and soil erosion. The practice of crushing and returning smaller rock fragments to the field could reduce the above problems. The aim of this work was to test the addition of rock fragments as practice to restore soil physical quality of not-stony soils susceptible to compaction. We carried out a lab experiment mixing five different volume concentrations (5%, 10%, 15%, 25% and 35%) of 4-8mm rock fragments with an Alfisol and an Entisol, showing compact structure and water stagnation problems in field. The repacked samples have undergone nine wet/dry cycles in order to induce soil structure formation and its stabilization. Bulk density, porosity and soil hydraulic properties and hydro-dispersive characteristics were measured. Soil hydraulic properties, namely water retention and hydraulic conductivity, were inferred from an infiltration experiment performed by a tension infiltrometer disc coupled with an inverse parameter estimation method; hydro-dispersive characteristics were performed from a tracer inflow-outflow experiment conducted in unsaturated condition, followed by the analysis of the breakthrough curve. Soil image analysis was used to enhance parameterization of the hydrological models near saturation. Preliminary results showed that bulk density significantly changed only after addition of 35% of rock fragments and a good physical restoration was reached at 15% volume concentration in Entisol and at 25% in Alfisol where hydro-dispersive characteristics strongly changed.

Gargiulo, Laura; Mele, Giacomo; Coppola, Antonio; De Mascellis, Roberto; Di Matteo, Bruno; Terribile, Fabio; Basile, Angelo

2014-05-01

254

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

Microsoft Academic Search

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

Francisco J. Arriaga; Birl Lowery

2003-01-01

255

Tillage Effects on Dryland Soil Physical Properties in Northeastern Montana  

Microsoft Academic Search

We evaluated the effect of no tillage (NT) and conventional tillage (CT) on soil penetration resistance (PR), bulk density (BD), gravimetric moisture content (MC), and saturated hydraulic conductivity (Ks) during the fallow phase of a spring wheat–fallow rotation. The study was conducted on two soils mapped as Williams loam at the Froid and Sidney sites. Soil measurements were made on

J. D. Jabro; U. M. Sainju; A. W. Lenssen; R. G. Evans

2011-01-01

256

Lunar soil properties and soil mechanics  

NASA Technical Reports Server (NTRS)

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

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

1974-01-01

257

A Hydraulic Model Is Compatible with Rapid Changes in Leaf Elongation under Fluctuating Evaporative Demand and Soil Water Status.  

PubMed

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

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

2014-04-01

258

A Robust-Resistant Approach to Interpret Spatial Behavior of Saturated Hydraulic Conductivity of a Glacial Till Soil Under No-Tillage System  

Microsoft Academic Search

A central Iowa glacial till soil under no-tillage condition was studied for its spatial behavior of saturated hydraulic conductivity (K) at the surface soil layers. Hydraulic conductivity measurements both in situ and in the laboratory were made at two depths of 15 and 30 cm at regular intervals of 4.6 m on two perpendicular transects crossing each other at the

B. P. Mohanty; R. S. Kanwar; R. Horton

1991-01-01

259

Cattle trampling and soil compaction effects on soil properties of a northeastern Nigerian sandy loam  

Microsoft Academic Search

Field studies on the effects of cattle trampling and soil compaction were conducted on sandy loam soils in Northeastern Nigeria. Cattle trampling significantly (P ? 0.001) increased soil bulk density and cone penetrometer resistance. Trampling produced dense zones at a depth of 7.5 cm, which reduced infiltration, in spite of the existence of numerous macropores. Hydraulic conductivity and infiltration rate

Hammanjoda Usman

1994-01-01

260

A harmonized vocabulary for soil observed properties  

NASA Astrophysics Data System (ADS)

Interoperability of soil data depends on agreements concerning models, schemas and vocabularies. However, observed property terms are often defined during different activities and projects in isolation of one another, resulting in data that has the same scope being represented with different terms, using different formats and formalisms, and published in various access methods. Significantly, many soil property vocabularies conflate multiple concepts in a single term, e.g. quantity kind, units of measure, substance being observed, and procedure. Effectively, this bundles separate information elements into a single slot. We have developed a vocabulary for observed soil properties by adopting and extending a previously defined water quality vocabulary. The observed property model separates the information elements, based on the Open Geospatial Consortium (OGC) Observations & Measurements model and extending the NASA/TopQuadrant 'Quantities, Units, Dimensions and Types' (QUDT) ontology. The imported water quality vocabulary is formalized using the Web Ontology Language (OWL). Key elements are defined as sub-classes or sub-properties of standard Simple Knowledge Organization System (SKOS) elements, allowing use of standard vocabulary interfaces. For the soil observed property vocabulary, terms from QUDT and water quality are used where possible. These are supplemented with additional unit of measure (Unit), observed property (ScaledQuantityKind) and substance being observed (SubstanceOrTaxon) vocabulary entries required for the soil properties. The vocabulary terms have been extracted from the Australian Soil and Land Survey Field Handbook and Australian Soil Information Transfer and Evaluation System (SITES) vocabularies. The vocabulary links any chemical substances to items from the Chemical Entities of Biological Interest (ChEBI) ontology. By formalizing the model for observable properties, and clearly labelling the separate elements, soil property observations may be more easily mapped to the OGC Observations & Measurements model for cross-domain applications.

Simons, Bruce; Wilson, Peter; Cox, Simon; Vleeshouer, Jamie

2014-05-01

261

Evidence of hydraulic lift in a young beech and oak mixed forest using 18 O soil water labelling  

Microsoft Academic Search

Hydraulic lift (HL) by tree roots in a young, broad-leaved, mixed temperate European forest was investigated during the 2008\\u000a growing season by injecting 18O-enriched soil water at a depth of 75–90 cm under drought conditions experimentally imposed in a rain-exclusion system. Based\\u000a on sap flow, leaf water potential, 2-D root distribution measurements, soil isotope profiles, and xylem water isotope composition,\\u000a water

Marion Zapater; Christian Hossann; Nathalie Bréda; Claude Bréchet; Damien Bonal; André Granier

262

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

Microsoft Academic Search

A method is described for the joint use of time-lapse ground-penetrating radar (GPR) travel times and hydrological data to estimate field-scale soil hydraulic parameters. We build upon previous work to take advantage of a wide range of cross-borehole GPR data acquisition configurations and to accommodate uncertainty in the petrophysical function, which relates soil porosity and water saturation to the effective

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

2005-01-01

263

Measuring hydraulic conductivity in a cracking clay soil using the Guelph Permeameter  

SciTech Connect

Knowing the variation of field-saturated hydraulic conductivity (K) with space, time and antecedent soil moisture conditions can be important for optimum management of cracking clay soils. The Guelph Permeameter (GP) method is a potentially valuable technique for measuring K and its variation in cracking soils, but concerns exist regarding (1) impacts of smearing and compaction in the GP well on the K measurement, (2) accurate detection of when steady flow from the GP is attained, and (3) time required for the GP to reach steady flow (equilibration time). These concerns were investigated for a series of GP measurements in a cracking clay soil (Vertic Xerochrept) in Sicily by testing flow and equilibration time. The mean K values (11.4--22.1 mm/h) obtained from the GP measurements were 1--3 orders of magnitude larger than what might be expected for a clayey texture, indicating that ponded infiltration from the GP wells occurred primarily through highly permeable soil shrinkage cracks, rather than through the low permeability clayey matrix. Wells that were treated with the plucking implement produced a non-significant (P < 0.05) factor of 1.94 increase in mean K relative to untreated wells, suggesting that this method for removing smearing and compaction functioned primarily by reopening partially smeared-over shrinkage cracks or other macropores. Relatively short mean equilibration times were obtained for the GP measurements (11--42 min), suggesting that the GP method can measure the soil's antecedent K before wetting from the well causes enough soil swelling to produce a declining permeability. The traditional four equal readings (FR) procedure is estimating GP equilibration time substantially underestimated the more recent visual estimation (VE) and the new cumulative drop (CD) procedures. This underestimation by the FR procedure resulted in overestimates of K relative to the VE and CD procedures for K values less than about 4 mm/h. It was concluded that the GP method can be a viable technique for measuring K in cracking clay soil.

Bagarello, V.; Iovino, M.; Reynolds, W.D.

1999-08-01

264

Using the single-ring infiltrometer method to detect temporal changes in surface soil field-saturated hydraulic conductivity  

Microsoft Academic Search

Determining temporal changes in field-saturated hydraulic conductivity (Kfs) is important for understanding and modelling hydrological phenomena at the field scale. Little is known about the sensitivity of temporal change estimates to the method used for measuring Kfs. The objective of this study was to compare temporal changes in Kfs obtained in the surface layer of a clayey soil using two

V Bagarello; A Sgroi

2004-01-01

265

Interpolating Soil Properties Using Kriging Combined with Categorical Information of Soil Maps  

Microsoft Academic Search

Kriging interpolation is frequently used for mapping soil properties in the analysis and interpretation of spatial variation of soil. Mapping quality could affect the performance of site-specific management. Soil map-delineation in existing soil maps showing abrupt changes at the boundaries between different soil types can provide valuable cate- gorical information for interpreting variation in soil properties. In this study, map

Ten-Lin Liu; Kai-Wei Juang; Dar-Yuan Lee

2006-01-01

266

Effect of the method of estimation of soil saturated hydraulic conductivity with regards to the design of stormwater infiltration trenches  

NASA Astrophysics Data System (ADS)

Best management practices are based on the infiltration of stormwater (e.g. infiltration into basins or trenches) to reduce the risk of flooding of urban areas. Proper estimations of saturated hydraulic conductivity of the vadose zone are required to avoid inappropriate design of infiltration devices. This article aims at assessing (i) the method-dependency of the estimation of soils saturated hydraulic conductivity and (ii) the consequences of such dependency on the design of infiltration trenches. This is illustrated for the specific case of an infiltration trench to be constructed to receive stormwater from a specific parking surface, 250 m2 in area, in Recife (Brazil). Water infiltration experiments were conducted according to the Beerkan Method, i.e. application of a zero water pressure head through a disc source (D=15 cm) and measures of the amount of infiltrated water with time. Saturated hydraulic conductivity estimates are derived from the analysis of these infiltration tests using several different conceptual approaches: one-dimensional models of Horton(1933) and Philip(1957), three-dimensional methods recently developed (Lassabatere et al., 2006, Wu et al., 1999, and Bagarello et al., 2013) and direct 3-dimensional numerical inversion. The estimations for saturated hydraulic conductivity ranged between 65.5 mm/h and 94 mm/h for one-dimensional methods, whereas using three-dimensional methods saturated hydraulic conductivity ranged between 15.6 mm/h and 50 mm/h. These results shows the need for accounting for 3D geometry, and more generally, the physics of water infiltration in soils, if a proper characterization of soil saturated hydraulic conductivity is targeted. In a second step, each estimate of the saturated hydraulic conductivity was used to calculate the stormwater to be stored in the studied trench for several rainfall events of recurrence intervals of 2 to 25 years. The calculation of these volumes showed a great sensitivity with regards to the estimated values of saturated hydraulic conductivity. The designed volumes of the trench vary from 8.3 m3 to 15.9 m3 for one-dimensional methods and 11.9 m3 to 24.5 m3 for three-dimensional methods, respectively. The results show that any miss-estimation of the saturated hydraulic conductivity of soils may drastically impact the design of infiltration devices and the related extra-costs. Bagarello, B.; Castellini, M.; Di Prima,S.;Giordano ,G.; Iovino, M. (2013). Testing a simplified approach to determine field saturated soil hydraulic conductivity. Procedia Environmental Sciences 19 ( 2013 ) 599 - 608 Horton, R. (1933). The role of infiltration in the hydrologic cycle. American Geophysical Union Transactions 14, 446-460. Lassabatère, L.; Angulo-Jaramillo, R.; Soria, J.M.; Cuenca, R.; Braud, I.; Haverkamp, R.(2006). Beerkan estimation of soil transfer parameters through infiltration experiments - BEST. Soil Science Society of American Journal, Madison, v.70, p.521-532, 2006. Philip, J.R. (1957). The theory of Infiltration: 5. The Influence of the Initial Moisture Content. Soil Science, v.4, n.84, p.329-339, 1957. Wu, L.; Pan, L.; Mitchell, J.; Sanden, B. (1999). Measuring satured hydraulic conductivity using a generalized solution for single-ringle infiltrometers. Soil Sci.Soc.Am.J.63, 788-792

Paiva coutinho, Artur; Predelus, Dieuseul; Lassabatere, Laurent; Ben Slimene, Erij; Celso Dantas Antonino, Antonio; Winiarski, Thierry; Joaquim da Silva Pereira Cabral, Jaime; Angulo-Jaramillo, Rafael

2014-05-01

267

Experimental and numerical study of infiltration into arid soils with contrasting physical and textural properties  

NASA Astrophysics Data System (ADS)

Dye infiltration tests were performed in the arid environments of the Ti Tree catchment, Central Australia. This area has a mean annual precipitation of 300 mm and is further known to have infrequent intensive rainfall events linked to short-term flooding. The mechanisms of groundwater recharge in these arid environments are generally unknown. The upper 1-2 m of soil play an important role in water redistribution with preferential flow often contributing to inhomogeneous moisture storage, soil water flow and groundwater recharge. Reducing uncertainty in recharge estimation thus requires a detailed study of water flow especially near the soil surface where heterogeneity may be enhanced by biological activity and geomorphological processes. Each of three infiltration tests involved application of 100 L of a mixed dye solution applied by using a standard 60-cm diameter ring infiltrometer under constant-head ponded conditions. After complete water infiltration several vertical soil sections were prepared in a soil block of approximately 1.5-2 m3. Staining patterns were photographed to provide evidence of preferential flow while numerous disturbed and undisturbed samples were collected and analysed in the laboratory to determine soil physical and hydraulic properties including saturated hydraulic conductivity, water retention curve, initial moisture content prior to dye application and bulk densities. Staining patterns in the top 30-40 cm were relatively homogeneous with some fingering. However, presence of a textural break (fine over coarse sand) hypothesized to represent a paleo-riverbed significantly affected redistribution of water, possibly acting as a capillary barrier. Measurements of soil physical properties and soil profile digital photos were used to build a 3D heterogeneous soil hydraulic property model in HYDRUS-3D. Model results for the infiltration tests were quantitatively and qualitatively compared to staining patterns obtained during field experiments. Such studies are important for building better vadose zone models capable of modeling large-scale recharge processes.

Gerke, Kirill; Edde, Ambre; Mallants, Dirk

2013-04-01

268

Mechanical properties of natural hydraulic lime-based mortars  

Microsoft Academic Search

One hundred eighty different mortars made with a natural hydraulic lime (NHL) and different kinds of aggregates were prepared to be used in restoration works. The factors affecting the mechanical behavior have been studied at long-term test. Compressive and flexural strengths of the specimens were discussed according to curing time, binder\\/aggregate ratios, attributes of the aggregates and porosity.Three phases of

J. Lanas; J. L. Pérez Bernal; M. A. Bello; J. I. Alvarez Galindo

2004-01-01

269

Effects of a vermicompost composted with beet vinasse on soil properties, soil losses and soil restoration  

Microsoft Academic Search

The use of organic rich wastes instead or as a complement of mineral fertilizers is considered a good environmental practice, provided that the organic wastes are not severely polluted (e.g. occurrence of heavy metals, organic pollutants and\\/or pathogens). However, the effect of a particular organic waste on soil properties, soil loss and soil restoration depends on its chemical composition. In

M. Tejada; A. M. García-Martínez; J. Parrado

2009-01-01

270

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

Microsoft Academic Search

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

F. Maggi; C. E. Pallud

2010-01-01

271

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

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

272

Using electrical resistivity tomography (ERT) to image the topology of soil properties relevant to solute transport characteristics of soils  

NASA Astrophysics Data System (ADS)

It is widely recognized that not only the local hydraulic properties but also their topology and connectivity as well as interfaces between soil layers and domains are important to model the effective flow and transport characteristics of soils. In order to fully understand how the structural soil properties are related to solute transport properties, the above discussed features have to be imaged with 3-D spatial resolution. Recent studies have shown that electrical resistivity tomography (ERT) can be used to obtain quantitative information about the structure of solute transport (Koestel et al. 2009. Noninvasive 3-D Transport Characterization in a Sandy Soil Using ERT: 2. Transport Process Inference. Vadose Zone Journal 8: 723-734). In this study we demonstrate that ERT can also be applied to derive the topology of hydraulic property-related parameters, namely (i) the mineral surface electrical conductivity (sigma_s) which is a proxy for the clay content and (ii) the electrical formation factor (F) which is a parameter in which porosity, water saturation, and geometry of wetted and non-wetted pore space are lumped. We apply the method to image sigmas and F of four large lysimeters (height: 1.4 m, radius 0.58 m), three of them filled with an undisturbed soil sample and one containing a virtual porous medium (generated with Gaussian random fields). We discuss the result with respect to soil texture, water content measurements, and optically derived soil structures. In a next step, we compare the ERT-derived sigmas and F to the corresponding ERT-derived apparent convection-dispersion parameters. The results of the numerical experiment are used to investigate the accuracy of the ERT images and the benefits and caveats of our approach.

Koestel, John; Garré, Sarah; Javaux, Mathieu; Vanderborght, Jan; Vereecken, Harry

2010-05-01

273

Impact of soil properties on selected pharmaceuticals adsorption in soils  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

274

Effects of surfactants and electrolyte solutions on the properties of soil  

NASA Astrophysics Data System (ADS)

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

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

2006-04-01

275

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

NASA Astrophysics Data System (ADS)

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

Vannier, Olivier; Braud, Isabelle; Anquetin, Sandrine

2013-04-01

276

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

PubMed Central

We investigated the role of xylem cavitation, plant hydraulic conductance, and root pressure in the response of rice (Oryza sativa) gas exchange to water stress. In the field (Philippines), the percentage loss of xylem conductivity (PLC) from cavitation exceeded 60% in leaves even in watered controls. The PLC versus leaf water potential relationship indicated diurnal refilling of cavitated xylem. The leaf water potential causing 50 PLC (P50) was –1.6 MPa and did not differ between upland versus lowland rice varieties. Greenhouse-grown varieties (Utah) were more resistant to cavitation with a 50 PLC of –1.9 MPa but also showed no difference between varieties. Six-day droughts caused concomitant reductions in leaf-specific photosynthetic rate, leaf diffusive conductance, and soil-leaf hydraulic conductance that were associated with cavitation-inducing water potentials and the disappearance of nightly root pressure. The return of root pressure after drought was associated with the complete recovery of leaf diffusive conductance, leaf-specific photosynthetic rate, and soil-leaf hydraulic conductance. Root pressure after the 6-d drought (61.2 ± 8.8 kPa) was stimulated 7-fold compared with well-watered plants before drought (8.5 ± 3.8 kPa). The results indicate: (a) that xylem cavitation plays a major role in the reduction of plant hydraulic conductance during drought, and (b) that rice can readily reverse cavitation, possibly aided by nocturnal root pressure.

Stiller, Volker; Lafitte, H. Renee; Sperry, John S.

2003-01-01

277

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

NASA Astrophysics Data System (ADS)

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

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

2006-12-01

278

Effect of cryogel on soil properties  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

279

Variability of magnetic soil properties in Hawaii  

NASA Astrophysics Data System (ADS)

Magnetic soils can seriously hamper the performance of electromagnetic sensors for the detection of buried land mines and unexploded ordnance (UXO). Soils formed on basaltic substrates commonly have large concentrations of ferrimagnetic iron oxide minerals, which are the main cause of soil magnetic behavior. Previous work has shown that viscous remanent magnetism (VRM) in particular, which is caused by the presence of ferrimagnetic minerals of different sizes and shapes, poses a large problem for electromagnetic surveys. The causes of the variability in magnetic soil properties in general and VRM in particular are not well understood. In this paper we present the results of laboratory studies of soil magnetic properties on three Hawaiian Islands: O"ahu, Kaho"olawe, and Hawaii. The data show a strong negative correlation between mean annual precipitation and induced magnetization, and a positive correlation between mean annual precipitation and the frequency dependent magnetic behavior. Soil erosion, which reduces the thickness of the soil cover, also influences the magnetic properties.

van Dam, Remke L.; Harrison, J. Bruce J.; Hendrickx, Jan M. H.; Borchers, Brian; North, Ryan E.; Simms, Janet E.; Jasper, Chris; Smith, Christopher W.; Li, Yaoguo

2005-06-01

280

Hydraulic characterization of dual-permeability unsaturated soils using tension disc infiltration experiments: BEST-2K method  

NASA Astrophysics Data System (ADS)

Modelling and understanding water flow and solute transfer in the vadose zone require accounting for preferential flow and physical non-equilibrium transport. The dual permeability approach was developed to model preferential flow. This approach conceptualizes soils as having structural pores representing the fast flow region and the soil matrix with a much lower saturated hydraulic conductivity, with a first-order lateral exchange of water between the two regions. The use of such approach requires the knowledge of the hydraulic functions, i.e. the water retention and hydraulic conductivity functions, for both the matrix and fast flow regions. In this paper, we investigate the design of a new method, referred to as BEST-2K, to characterize the hydraulic functions of dual permeability media from water infiltration experiments. BEST-2K is based on the basics of the so-called BEST method. This method was previously developed to derive the hydraulic functions of single permeability media using single tension water infiltration (e.g., zero pressure head at surface for the Beerkan method). For BEST-2K, two successive water infiltrations are required: one at a constant water pressure head of -15 cm to activate the matrix porosity without macropores (i.e., pores more than 0.2mm in size) and the second with a zero pressure head at surface in order to activate the complementary fast flow porosity. From an experimental point of view, the two infiltrations can be successively conducted using a tension disc infiltrometer. The first cumulative infiltration is analysed with BEST method to derive the hydraulic functions of the matrix alone. The knowledge of the matrix hydraulic functions allows the calculation of cumulative infiltration component through the matrix during the second infiltration. The amount of water infiltrated into the fast flow region is then deduced by subtraction and is used to derive the hydraulic functions of the fast flow region. The proposed BEST-2K method is validated against analytical generated infiltration data to assess its precision and its robustness. At last, its use is detailed for specific sets of experimental data obtained with two coarse materials suspected to match dual-permeability behaviour. The results show that new BEST-2K algorithm is a promising tool for the hydraulic characterisation of heterogeneous soils.

Lassabatere, Laurent; Angulo-Jaramillo, Rafael; Yilmaz, Deniz; Peyrard, Xavier

2014-05-01

281

Innovative in-situ determination of unsaturated hydraulic properties in deep loess sediments in north-west Bulgaria  

SciTech Connect

In the framework of selecting a suitable site for final disposal of low- and intermediate level short-lived radioactive waste (LILW-SL) in Bulgaria, site characterization is ongoing at the Marichin Valog site, North-West Bulgaria. The site is characterized by a complex sequence of loess, clayey gravel, and clay layers, of which the first 30-40 m are unsaturated. Proper knowledge about unsaturated water flow and concomitant radionuclide transport is key input to safety assessment calculations. Constant-head infiltrometer tests were carried out at several meters below ground surface to determine the unsaturated hydraulic properties of silty loess, clayey loess, and clayey gravel layers. Individual infiltrometers were equipped with 0.5-m-long filter sections; the shallowest filter was from 2 to 2.5 m depth, whereas the deepest was from 9.5 to 10 m depth. Infiltration tests provided data on cumulative infiltration and progression of the wetting front in the initially unsaturated sediments surrounding the infiltrometer. A cylindrical time-domain reflectometry TRIME probe was used to measure water content variations with time during progression of the wetting front. Access tubes for the TRIME probe were installed at 0.3 to 0.5 m from the infiltrometer tubes. By means of an inverse optimization routine implemented in the finite element code HYDRUS-2D, field-scale soil hydraulic parameters were derived for all layers. Results show a great consistency in the optimized parameter values, although the test sites were several meters apart. Apparently the size of the affected volume of soil was large enough to reduce the effect of spatial variability and to produce average field-scale hydraulic parameters that are relevant for large-scale predictions of flow patterns and radionuclide migration pathways. (authors)

Mallants, Dirk; Perko, Janez [Belgian Nuclear Research Centre, (SCK.CEN), B-2400 Mol (Belgium); Antonov, Dimitar; Karastanev, Doncho [Geological Institute, Bulgarian Academy of Sciences (Bulgaria)

2007-07-01

282

Determining the Porosity and Saturated Hydraulic Conductivity of Binary Mixtures  

Microsoft Academic Search

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

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

2011-01-01

283

Determining the Porosity and Saturated Hydraulic Conductivity of Binary Mixtures  

Microsoft Academic Search

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

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

2009-01-01

284

Role of soil properties in sewage sludge toxicity to soil collembolans  

Microsoft Academic Search

Soil properties are one of the most important factors explaining the different toxicity results found in different soils. Although there is knowledge about the role of soil properties on the toxicity of individual chemicals, not much is known about its relevance for sewage sludge amendments. In particular little is known about the effect of soil properties on the toxicity modulation

Xavier Domene; Joan Colón; Maria Vittoria Uras; Rebeca Izquierdo; Anna Àvila; Josep M. Alcañiz

2010-01-01

285

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

EPA Science Inventory

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

286

Evolution of unsaturated hydraulic properties of municipal solid waste with landfill depth and age.  

PubMed

Successful modeling of liquid and air flow and hence designing of liquid and air addition systems in the landfills are constrained by the lack of key parameters of unsaturated hydraulic properties of municipal solid waste (MSW), which are strongly dependent on the depth of burial and the degree of decomposition. In this study, water retention curves (WRC) of MSW are measured using pressure plate method on samples repacked according to the in situ unit weight measured during borehole sampling, representing the MSW in shallow, middle, and deep layers. The measured WRC of MSW is well-reproduced by the van Genuchten-Mualem model, and is used to predict the unsaturated hydraulic properties of MSW, including water retention characteristics and unsaturated hydraulic conductivity. The estimated model parameters are consistent with other studies, suggesting that the pressure plate method yields reproducible results. As the landfill depth and age increase, the overburden pressure, the highly decomposed organic matter and finer pore space increase, hence the capillary pressure increases, causing increases in air-entry values, field capacity and residual water content, and decreases in steepness of WRC and saturated water content. The unsaturated hydraulic properties of MSW undergo changes with landfill depth and age, showing more silt loam-like properties as the landfill age increases. PMID:22289482

Wu, Huayong; Wang, Hongtao; Zhao, Yan; Chen, Tan; Lu, Wenjing

2012-03-01

287

Fracture fluid flow properties investigation using GPR and hydraulic testing methods  

Microsoft Academic Search

Characterization of the fluid flow properties of fractures is of particular interest because fractures rapidly transmit fluids, such as groundwater, contaminants and hydrocarbons. We investigate the use of ground-penetrating radar (GPR) and hydraulic testing to characterize groundwater flow variability along two prominent horizontal fracture planes in a carbonate aquifer. Three-dimensional radar reflection surveying provided high- resolution imaging of the two

Georgios P. Tsoflias; T. Halihan; M. A. Muldoon

2004-01-01

288

Normal-stress dependence of fracture hydraulic properties including two-phase flow properties  

NASA Astrophysics Data System (ADS)

A systematic approach has been developed for determining relationships between normal stress and fracture hydraulic properties, including two-phase flow properties. The development of a relationship between stress and fracture permeability (or fracture aperture and fracture closure) is based on a two-part Hooke's model (TPHM) that captures heterogeneous elastic-deformation processes at a macroscopic scale by conceptualizing the rock mass (or a fracture) into two parts with different mechanical properties. The developed relationship was verified using a number of datasets in the literature for fracture closure versus stress, and satisfactory agreements were obtained. TPHM was previously shown to be able to accurately represent testing data for porous media as well. Based on the consideration that fracture-aperture distributions under different normal stresses can be represented by truncated-Gaussian distributions, closed-form constitutive relationships were developed between capillary pressure, relative permeability and saturation, for deformable horizontal fractures. The usefulness of these relationships was demonstrated by their consistency with a laboratory dataset.

Liu, Hui-Hai; Wei, Ming-Yao; Rutqvist, Jonny

2013-03-01

289

Quasi-steady centrifuge method for unsaturated hydraulic properties  

USGS Publications Warehouse

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

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

2005-01-01

290

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

Microsoft Academic Search

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

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

291

Change of soil physical properties under long-term natural vegetation restoration in the Loess Plateau of China  

Microsoft Academic Search

A 150-year chronological study of semi-arid abandoned farmland in the central Loess Plateau of China indicated that soil physical properties were closely related to the date of being abandoned and the vegetation recovery stages. Bulk density of the surface layer (0–20cm) significantly reduced with time while soil porosity, water-holding capacity, aggregate stability, and saturated hydraulic conductivity significantly increased. In the

Y. Y. Li; M. A. Shao

2006-01-01

292

The use of One-Dimensional Laboratory Experiments to Assess Hydraulic Processes in Wastewater Soil Absorption Systems  

NASA Astrophysics Data System (ADS)

Sixteen, one-dimensional column lysimeters have been developed to evaluate the influence of loading regime and infiltrative surface character on hydraulic performance in wastewater soil absorption systems. A duplicate design was utilized to evaluate two infiltrative surface conditions (gravel-free vs. gravel-laden) under four hydraulic loading regimes representative of possible field conditions. By loading the columns at rates of 25 to 200 cm/day, the 17 weeks of column operation actually reflect up to approximately 13 yrs of field operation (at 5 cm/day). Therefore, the cumulative mass throughput and infiltrative rate loss for each loading regime can be examined to determine the viability of accelerated loading as a means to compress the time scale of observation, while still producing meaningfully results for the field scale. During operation, the columns were loaded with septic tank effluent at a prescribed rate and routinely monitoring for applied effluent composition, infiltration rate, time-dependant soil water content, water volume throughput, and percolate composition. Bromide tracer tests were completed prior to system startup and at weeks 2, 6, and 17 of system operation. Hydraulic characterization of the columns is based on measurements of the hydraulic loading rate, volumetric throughput, soil water content, and bromide breakthrough curves. Incipient ponding of wastewater developed during the 1st week of operation for columns loaded at the highest hydraulic rate (loading regimes 1 and 2), and during the 3rd and 6th week of operation for loading regimes 3 and 4, respectfully. The bromide breakthrough curves exhibit later breakthrough and tailing as system life increases, indicating the development of spatially variability in hydraulic conductivity within the column and the development of a clogging zone at the infiltrative surface. Throughput is assessed for each loading regime to determine the infiltration rate loss versus days of operation. Loading regimes 1 and 2 approach a comparable long-term throughput rate less than 20 cm/day, while loading regimes 3 and 4 reach a long-term throughput rate of less than 10 cm/day. These one-dimensional columns allow for the analysis of infiltrative rate loss and hydraulic behavior as a result of infiltrative surface character and loading regime.

Huntzinger, D. N.; McCray, J. E.; Siegrist, R.; Lowe, K.; VanCuyk, S.

2001-05-01

293

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

Microsoft Academic Search

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

Lee Slater

2007-01-01

294

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

SciTech Connect

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

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

1996-08-01

295

Effect of root refuse of liquorice on different characteristics of soils from southern regions of Iran. III. Structure and hydraulic conductivity of soils under saline sodic conditions  

Microsoft Academic Search

Population increase and increasing demand for food have extended agriculture to troublesome lands with different problems, e.g., salinity and deficiency of organic matter. Although, even the application of a little amount of organic matter may have great effects in improving microbial, chemical, and physical properties of soil, but organic matter management in all soils, especially saline–sodic soils is difficult, and

M. Sameni; A. Tajabadi Pour

2001-01-01

296

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

SciTech Connect

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

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

1996-03-01

297

Quantification of soil shrinkage in 2D by digital image processing of soil surface  

Microsoft Academic Search

Knowledge of soil shrinkage behavior is needed to improve the understanding and prediction of changes of unsaturated hydraulic properties in non-rigid soils. The heterogeneity and interaction of horizontal and vertical soil shrinkages that produce soil cracks and associated soil subsidence require additional quantification. Vertical shrinkage can be calculated easily by soil height with vernier caliper. However, a quantitative and feasible

X. Peng; R. Horn; S. Peth; A. Smucker

2006-01-01

298

Rock fragments and soil physical properties in the fire-prone Portuguese schist region  

NASA Astrophysics Data System (ADS)

Fires often occur on shallow or stony soils. In Portugal for instance, one of the most fire-prone countries in Europe, 51% of the fires between 1990 and 2008 occurred on shallow soils ( 2300 topsoil samples collected at 13 sites in the Portuguese schist region in north-central Portugal. Soil physical properties assessed include soil water retention, saturated hydraulic conductivity, soil water repellency, bulk density and soil organic matter content. I will additionally show how surface rock fragments, and rock fragments incorporated into the soil, affect soil temperatures during fire. The particle density of these rock fragments was determined at 2.36 g cm-3 (for particles 2-20 mm), indicating that use of the common value of 2.65 g cm-3 to calculate rock fragment volume from their weight may lead to underestimation of the volume of rock fragments in the soil, and an associated underestimation of the bulk density of the fine earth fraction. The differences and commonalities between sites will be highlighted, and the impacts of rock fragments on fire impact and soil hydrology in fire-prone environments discussed.

Stoof, Cathelijne R.

2014-05-01

299

Properties of lunar soil simulant JSC-1  

NASA Astrophysics Data System (ADS)

With the establishment of a lunar base, many tasks will require direct interaction between the in-situ lunar soil and a wide variety of instruments and implements. The individual tasks may be scientific in nature, or simply the manipulation of the lunar soil. To help fulfill the need for relatively large quantities of lunar soil simulant in researching these operations, Johnson Space Center has developed a new simulant called JSC-1. It is produced from a basaltic pyroclastic sheet deposit located in the San Francisco volcanic field near Flagstaff, Arizona. JSC-1 is a crushed, ground, and sieved material that was developed to have similar mechanical properties and characteristics of the lunar soil. Furthermore, this glass-rich basaltic ash can be used in chemical or mineralogical resource studies. The Lunar Soil Simulant Laboratory, at the Civil Engineering Department, at Texas A&M University, is responsible for analyzing, storing, and distributing this material to qualified researchers. Information regarding the availability of JSC-1 is provided at the end of the paper. The purpose of this paper is to assess JSC-1 as a close terrestrial analog of the lunar soil and to inform the research community of the availability of the new simulant.

Willman, Brian M.; Boles, Walter W.; McKay, David S.; Allen, Carlton C.

1995-04-01

300

Design and Management of Subsurface Soil Absorption Systems.  

National Technical Information Service (NTIS)

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 prac...

E. J. Tyler W. C. Boyle J. C. Converse R. L. Siegrist D. L. Hargett

1985-01-01

301

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...

302

Property-Transfer Modeling to Estimate Unsaturated Hydraulic Conductivity of Deep Sediments at the Idaho National Laboratory, Idaho  

USGS Publications Warehouse

The unsaturated zone at the Idaho National Laboratory is complex, comprising thick basalt flow sequences interbedded with thinner sedimentary layers. Understanding the highly nonlinear relation between water content and hydraulic conductivity within the sedimentary interbeds is one element in predicting water flow and solute transport processes in this geologically complex environment. Measurement of unsaturated hydraulic conductivity of sediments is costly and time consuming, therefore use of models that estimate this property from more easily measured bulk-physical properties is desirable. A capillary bundle model was used to estimate unsaturated hydraulic conductivity for 40 samples from sedimentary interbeds using water-retention parameters and saturated hydraulic conductivity derived from (1) laboratory measurements on core samples, and (2) site-specific property transfer regression models developed for the sedimentary interbeds. Four regression models were previously developed using bulk-physical property measurements (bulk density, the median particle diameter, and the uniformity coefficient) as the explanatory variables. The response variables, estimated from linear combinations of the bulk physical properties, included saturated hydraulic conductivity and three parameters that define the water-retention curve. The degree to which the unsaturated hydraulic conductivity curves estimated from property-transfer-modeled water-retention parameters and saturated hydraulic conductivity approximated the laboratory-measured data was evaluated using a goodness-of-fit indicator, the root-mean-square error. Because numerical models of variably saturated flow and transport require parameterized hydraulic properties as input, simulations were run to evaluate the effect of the various parameters on model results. Results show that the property transfer models based on easily measured bulk properties perform nearly as well as using curve fits to laboratory-measured water retention for the estimation of unsaturated hydraulic conductivity.

Perkins, Kim S.; Winfield, Kari A.

2007-01-01

303

Empirical Modeling of Relationships Between Sorghum Yield and Soil Properties  

Microsoft Academic Search

A crucial part of any site-specific management is the identification of causes of yield variability and assessment of crop requirements. Therefore, relationships between yield and soil properties must be identified. In this study, relationships between sorghum yield and soil properties on a verbosols within a field located in Moree, in northern NSW, Australia, were examined. Measured soil properties included pH;

T. M. Shatar; A. B. Mcbratney

1999-01-01

304

Biological properties of soils on mine tips  

NASA Astrophysics Data System (ADS)

The biological properties of soils forming on coalmine spoils composed of loose non-toxic rocks were studied. In ten years of observation, fungal biomass in the studied soils increased by 6 times; the population density of the main groups of bacteria, by 3-7 times, and the respiration intensity, by 5-6 times. The biochemical activity of the soils increased significantly; in particular, the enzymatic activity (especially, the hydrolase activity) increased by 3-8 times, and the processes of cellulose destruction and accumulation of ninhydrinpositive products intensified. The obtained results attest to colonization of the substrate by microorganisms and the development of microbial cenoses. This process is particularly active upon application of phytoameliorants.

Naprasnikova, E. V.

2008-12-01

305

Joint estimation of soil moisture profile and hydraulic parameters by ground-penetrating radar data assimilation with maximum likelihood ensemble filter  

NASA Astrophysics Data System (ADS)

Radar (GPR) has recently become a powerful geophysical technique to characterize soil moisture at the field scale. We developed a data assimilation scheme to simultaneously estimate the vertical soil moisture profile and hydraulic parameters from time-lapse GPR measurements. The assimilation scheme includes a soil hydrodynamic model to simulate the soil moisture dynamics, a full-wave electromagnetic wave propagation model, and petrophysical relationship to link the state variable with the GPR data and a maximum likelihood ensemble assimilation algorithm. The hydraulic parameters are estimated jointly with the soil moisture using a state augmentation technique. The approach allows for the direct assimilation of GPR data, thus maximizing the use of the information. The proposed approach was validated by numerical experiments assuming wrong initial conditions and hydraulic parameters. The synthetic soil moisture profiles were generated by the Hydrus-1D model, which then were used by the electromagnetic model and petrophysical relationship to create "observed" GPR data. The results show that the data assimilation significantly improves the accuracy of the hydrodynamic model prediction. Compared with the surface soil moisture assimilation, the GPR data assimilation better estimates the soil moisture profile and hydraulic parameters. The results also show that the estimated soil moisture profile in the loamy sand and silt soils converge to the "true" state more rapidly than in the clay one. Of the three unknown parameters of the Mualem-van Genuchten model, the estimation of n is more accurate than that of ? and Ks. The approach shows a great promise to use GPR measurements for the soil moisture profile and hydraulic parameter estimation at the field scale.

Tran, Anh Phuong; Vanclooster, Marnik; Zupanski, Milija; Lambot, Sébastien

2014-04-01

306

Using 137 Cs measurements to investigate the influence of erosion and soil redistribution on soil properties.  

PubMed

Information on the interaction between soil erosion and soil properties is an important requirement for sustainable management of the soil resource. The relationship between soil properties and the soil redistribution rate, reflecting both erosion and deposition, is an important indicator of this interaction. This relationship is difficult to investigate using traditional approaches to documenting soil redistribution rates involving erosion plots and predictive models. However, the use of the fallout radionuclide (137)Cs to document medium-term soil redistribution rates offers a means of overcoming many of the limitations associated with traditional approaches. The study reported sought to demonstrate the potential for using (137)Cs measurements to assess the influence of soil erosion and redistribution on soil properties (particle size composition, total C, macronutrients N, P, K and Mg, micronutrients Mn, Mo, Fe, Cu and Zn and other elements, including Ti and As). (137)Cs measurements undertaken on 52 soil cores collected within a 7 ha cultivated field located near Colebrooke in Devon, UK were used to establish the magnitude and spatial pattern of medium-term soil redistribution rates within the field. The soil redistribution rates documented for the individual sampling points within the field ranged from an erosion rate of -12.9 t ha(-1) yr(-1) to a deposition rate of 19.2 t ha(-1) yr(-1). Composite samples of surface soil (0-5 cm) were collected immediately adjacent to each coring point and these samples were analysed for a range of soil properties. Individual soil properties associated with these samples showed significant variability, with CV values generally lying in the range 10-30%. The relationships between the surface soil properties and the soil redistribution rate were analysed. This analysis demonstrated statistically significant relationships between some soil properties (total phosphorus, % clay, Ti and As) and the soil redistribution rate, but for most properties there was no significant relationship. This suggests that other factors, in addition to soil erosion and soil redistribution, are also important in causing spatial variability in soil properties, or that, because of the relatively deep soils, soil properties are relatively insensitive to soil redistribution processes. The importance of the erosional history of the field was explored using a simple model to predict changes in soil properties in response to the magnitude of the erosion or deposition rate and the length of the period during which the field had been subject to soil erosion and soil redistribution. PMID:21296581

Du, P; Walling, D E

2011-05-01

307

Influence of salinity on root hydraulic properties of three olive varieties  

Microsoft Academic Search

Three varieties of olive, Barnea, Arbequina and Proline, varying in salt tolerance, were examined to check the sensitivity of their root system hydraulic properties to salinity. Up to three levels of saline water (EC = 1.2, 4.2 and 7.5 dS m) were used for long-term irrigation of mature trees. Specific conductivities and embolism rates of roots and branches were estimated by low-pressure

B. Rewald; C. Leuschner; Z. Wiesman; J. E. Ephrath

2011-01-01

308

Prototype Database and User's Guide of Saturated Zone Hydraulic Properties forthe Hanford Site  

SciTech Connect

Predicting the movement of contaminants in groundwater beneath the Hanford Site is important for both understanding the impacts of these contaminants and for planning effective cleanup activities. These predictions are based on knowledge of the distribution of hydraulic properties within the aquifers underlying the Hanford Site. The Characterization of Systems (CoS) Task, under the Groundwater/Vadose Integration Project, is responsible for establishing a consistent set of data, parameters, and conceptual models to support estimates contaminant migration and impact.

Thorne, Paul D.; Newcomer, Darrell R.

2002-09-01

309

Do stone bunds affect soil physical properties? - A case study in northern Ethiopia  

NASA Astrophysics Data System (ADS)

Central issue of rain fed agriculture systems in the Ethiopian highlands is to store rain water in the soil during the rainy season (June to September). The aim is to maximize plant available water and to reduce surface runoff and soil erosion. Stone bunds are a common practice for soil and water conservation, influencing the translation processes of surface runoff. However, changes in surface hydrology affect the temporal and spatial properties of soil physical parameters. The objective of this research is to find a relationship between the spatial distribution of soil properties and the location of the stone bunds, but also to monitor the temporal behavior of those soil parameters, to better understand the impact of stone bunds on soil water movement. The research area is located in the Gumara Watershed, Maksegnit in Northern Ethiopia. There two representative transects were selected: One transect crosses three fields with conservation measures applied perpendicular to the stone bunds at a length of approximately 71 m. The second transect crosses a similar hill slope without conservation structures at a length of 55 m. During the rainy season in 2012 soil physical properties were monitored in specific spatial and temporal intervals. The measurements included bulk density, soil texture and volumetric water content. Tension infiltrometer tests were conducted to determine saturated and near saturated hydraulic conductivity for areas near stone bunds and the center of the fields on one hand, but also to derive van Genuchten parameters for those points inversely with Hydrus 2D. Slope steepness and stone cover along the transects were assessed, using survey and photogrammetric analysis. Preliminary results show an increase in the water content of topsoils within a range of approximately 2 m above the stone bunds but only random fluctuations in the field without conservation measures. At depths greater than 20 cm no significant differences in water content were found. Bulk density shows lower values in the areas above the stone bunds where sedimentation takes place. Slope steepness and stone cover also decrease in a range of a few meters above the stone bunds that also indicates sedimentation processes. Further analysis with consideration of the spatial and temporal distribution of the measurements may show influences on soil physical properties but also relationships between soil parameters (cross correlation). Showing a cyclic behavior of soil physical properties at the same spatial scale as the conservation measurements are placed may indicate a relationship between soil conditions and man-made conservation structures. Significant temporal changes of specific soil physical properties over the rainy season may allow a deeper insight in the impact of conservative measures on soil water balance.

Schürz, Christoph; Schwen, Andreas; Strohmeier, Stefan; Klik, Andreas

2013-04-01

310

Tensile mechanical properties and hydraulic permeabilities of electrospun cellulose acetate fiber meshes.  

PubMed

The mechanical properties and hydraulic permeabilities of biomaterial scaffolds play a crucial role in their efficacy as tissue engineering platforms, separation processors, and drug delivery vehicles. In this study, electrospun cellulose acetate fiber meshes of random orientations were created using four different concentrations, 10.0, 12.5, 15.0, and 17.5 wt % in acetone or ethyl acetate. The tensile mechanical properties and the hydraulic permeabilities of these meshes were measured, and a multiscale model was employed to predict their mechanical behavior. Experimentally, the elastic modulus ranged from 3.5 to 12.4 MPa depending on the polymer concentration and the solvent. Model predictions agreed well with the experimental measurements when a fitted single-fiber modulus of 123.3 MPa was used. The model also predicted that changes in fiber alignment may result in a 3.6-fold increase in the elastic modulus for moderately aligned meshes and a 8.5-fold increase for highly align meshes. Hydraulic permeabilities ranged from 1.4 x 10(-12) to 8.9 x 10(-12) m(2) depending on polymer concentration but not the choice of solvent. In conclusion, polymer concentration, fiber alignment, and solvent have significant impact on the mechanical and fluid transport properties of electrospun cellulose acetate fiber meshes. PMID:22887702

Stylianopoulos, Triantafyllos; Kokonou, Maria; Michael, Stefanos; Tryfonos, Antonia; Rebholz, Claus; Odysseos, Andreani D; Doumanidis, Charalambos

2012-11-01

311

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

PubMed Central

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.

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

2013-01-01

312

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

SciTech Connect

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

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

2005-05-05

313

Tillage system affects microbiological properties of soil  

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

314

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

PubMed

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

Õunapuu, Eele; Sellin, Arne

2013-07-01

315

Hydraulic properties of fronds from palms of varying height and habitat.  

PubMed

Because palms grow in highly varying climates and reach considerable heights, they present a unique opportunity to evaluate how environment and plant size impact hydraulic function. We studied hydraulic properties of petioles from palms of varying height from three species: Iriartea deltoidea, a tropical rainforest species; Mauritia flexuosa, a tropical rainforest, swamp species; and Washingtonia robusta, a subtropical species. We measured leaf areas, petiole cross-sectional areas, specific conductivity (K(S)), petiole anatomical properties, vulnerability to embolism and leaf water potentials and calculated petiole Huber values and leaf-specific conductivities (K(L)). Leaf and petiole cross-sectional areas varied widely with height. However, hydraulic properties including Huber values, K(S) and K(L), remained constant. The two palmate species, M. flexuosa and W. robusta, had larger Huber values than I. deltoidea, a pinnately-compound species which exhibited the highest K(S). Metaxylem vessel diameters and vascular bundle densities varied with height in opposing patterns to maintain petiole conductivities. I. deltoidea and W. robusta petioles had similar P(50) values (the point at which 50% of hydraulic conductivity is lost) averaged over all crown heights, but W. robusta exhibited more negative P(50) values in taller palms. Comparison of P (50) values with transpiring midday leaf water potentials, as well as a double-dye staining experiment in a 1-m-tall palm, suggested that a fairly significant amount of embolisms were occurring and refilled on a diurnal basis. Therefore, across palms differing widely in height and growing environments, we found convergence in water transport per unit leaf area (K(L)) with individuals exhibiting differing strategies for achieving this. PMID:21656029

Renninger, Heidi J; Phillips, Nathan

2011-12-01

316

Linking Amazonian secondary succession forest growth to soil properties  

Microsoft Academic Search

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

D. Lu; E. Moran; P. Mausel

2002-01-01

317

Deforestation effects on soil physical and chemical properties, Lordegan, Iran  

Microsoft Academic Search

Quantification of soil quality changes following deforestation by measurable soil attributes is important to sustainable management of soil and water conservation. A study was initiated in 1994 to evaluate the effects of deforestation on physical and chemical properties of soils under oak (Quercus brontii) forests in Lordegan region of central Zagrous mountain, Iran. Nine profiles which were derived from Bakhtiari

Mohammad A. Hajabbasi; Ahmad Jalalian; Hamid R. Karimzadeh

1997-01-01

318

Impact of hydraulic suction history on crack growth mechanics in soil  

Microsoft Academic Search

The mechanics of crack formation and the influence of soil stress history were described using the crack tip opening angle (CTOA) measured with fractography. Two soils were studied: a model soil consisting of 40% Ca-bentonite and 60% fine silica sand and a remolded paddy soil with similar clay content and mineralogy. Fracture testing used deep-notch bend specimens formed by molding

S. Yoshida; P. D. Hallett

2008-01-01

319

Plant potassium content modifies the effects of arbuscular mycorrhizal symbiosis on root hydraulic properties in maize plants.  

PubMed

It is well known that the arbuscular mycorrhizal (AM) symbiosis helps the host plant to overcome several abiotic stresses including drought. One of the mechanisms for this drought tolerance enhancement is the higher water uptake capacity of the mycorrhizal plants. However, the effects of the AM symbiosis on processes regulating root hydraulic properties of the host plant, such as root hydraulic conductivity and plasma membrane aquaporin gene expression, and protein abundance, are not well defined. Since it is known that K(+) status is modified by AM and that it regulates root hydraulic properties, it has been tested how plant K(+) status could modify the effects of the symbiosis on root hydraulic conductivity and plasma membrane aquaporin gene expression and protein abundance, using maize (Zea mays L.) plants and Glomus intraradices as a model. It was observed that the supply of extra K(+) increased root hydraulic conductivity only in AM plants. Also, the different pattern of plasma membrane aquaporin gene expression and protein abundance between AM and non-AM plants changed with the application of extra K(+). Thus, plant K(+) status could be one of the causes of the different observed effects of the AM symbiosis on root hydraulic properties. The present study also highlights the critical importance of AM fungal aquaporins in regulating root hydraulic properties of the host plant. PMID:22370879

El-Mesbahi, Mohamed Najib; Azcón, Rosario; Ruiz-Lozano, Juan Manuel; Aroca, Ricardo

2012-10-01

320

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

Microsoft Academic Search

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

Federico Maggi; Céline Pallud

2010-01-01

321

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

NASA Astrophysics Data System (ADS)

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

Hjerne, Calle; Nordqvist, Rune

2014-04-01

322

Biochemical properties of vineyard soils in Galicia, Spain.  

PubMed

In the present study we investigated changes in soil biochemical activity in vineyard soils. With this aim, soil samples (0-10 cm) from 15 vineyard soils developed on diverse parent materials were collected during winter. All soil samples were analysed for a large number of both general and specific biochemical properties. The values of all of the biochemical parameters analysed were extremely low, between 3 and 39% of the usual values obtained for native Galician soils under climax vegetation. To estimate the level of biochemical quality of vineyard soils, while avoiding the problem of comparing soils with totally different organic matter contents, a biochemical equilibrium equation was used. The results showed that vineyard soils are highly degraded soils, for which in the most extreme cases, the value of the biochemical equilibrium index was 13%, i.e. almost 8 times lower that in high quality soils such as climax soils. PMID:17316764

Miguéns, Tamara; Leirós, M A Carmen; Gil-Sotres, Fernando; Trasar-Cepeda, Carmen

2007-05-25

323

Photometric properties of Mars soils analogs  

USGS Publications Warehouse

We have measured the bidirectional reflectance of analogs of dry, wet, and frozen Martian soils over a wide range of phase angles in the visible spectral range. All samples were produced from two geologic samples: the standard JSC Mars-1 soil simulant and Hawaiian basaltic sand. In a first step, experiments were conducted with the dry samples to investigate the effects of surface texture. Comparisons with results independently obtained by different teams with similar samples showed a satisfying reproducibility of the photometric measurements as well as a noticeable influence of surface textures resulting from different sample preparation procedures. In a second step, water was introduced to produce wet and frozen samples and their photometry investigated. Optical microscope images of the samples provided information about their microtexture. Liquid water, even in relatively low amount, resulted in the disappearance of the backscattering peak and the appearance of a forward-scattering peak whose intensity increases with the amount of water. Specular reflections only appeared when water was present in an amount large enough to allow water to form a film at the surface of the sample. Icy samples showed a wide variability of photometric properties depending on the physical properties of the water ice. We discuss the implications of these measurements in terms of the expected photometric behavior of the Martian surface, from equatorial to circum-polar regions. In particular, we propose some simple photometric criteria to improve the identification of wet and/or icy soils from multiple observations under different geometries.

Pommerol, A.; Thomas, N.; Jost, B.; Beck, P.; Okubo, C.; McEwen, A. S.

2013-01-01

324

Effects of root-induced compaction on rhizosphere hydraulic properties--X-ray microtomography imaging and numerical simulations.  

PubMed

Soil compaction represents one of the most ubiquitous environmental impacts of human development, decreasing bulk-scale soil porosity and hydraulic conductivity, thereby reducing soil productivity and fertility. At the aggregate-scale however, this study shows that natural root-induced compaction increases contact areas between aggregates, leading to an increase in unsaturated hydraulic conductivity of the soils adjacent to the roots. Contrary to intuition, water flow may therefore be locally enhanced due to root-induced compaction. This study investigates these processes by using recent advances in X-ray microtomography (XMT) imaging and numerical water flow modeling to show evolution in interaggregate contact and its implications for water flow between aggregates under partially saturated conditions. Numerical modeling showed that the effective hydraulic conductivity of a pair of aggregates undergoing uniaxial deformation increased following a nonlinear relationship as the interaggregate contact area increased due to increasing aggregate deformation. Numerical modeling using actual XMT images of aggregated soil around a root surrogate demonstrated how root-induced deformation increases unsaturated water flow toward the root, providing insight into the growth, function, and water uptake patterns of roots in natural soils. PMID:21121599

Aravena, Jazmín E; Berli, Markus; Ghezzehei, Teamrat A; Tyler, Scott W

2011-01-15

325

Estimated hydraulic properties for the surficial-and bedrock-aquifer system, Meddybemps, Maine  

USGS Publications Warehouse

Analytical and numerical-modeling methods were used to estimate hydraulic properties of the aquifer system underlying the Eastern Surplus Company Superfund Site in Meddybemps, Maine. Estimates of hydraulic properties are needed to evaluate pathways for contaminants in ground water and to support evaluation and selection of remediation measures for contaminated ground water at this site. The hydraulic conductivity of surficial materials, determined from specific-capacity tests, ranges from 17 to 78 feet per day for wells completed in coarse-grained glaciomarine sediments, and from about 0.1 to 1.Ofoot per day for wells completed in till. The transmissivity of fractured bedrock determined from specific-capacity tests and aquifer tests in wells completed in less than 200 feet of bedrock ranges from about 0.09 to 130 feet squared per day. Relatively high values of transmissivity at the south end of the study area appear to be associated with a high-angle fracture or fracture zone that hydraulically connects two wells completed in bedrock. Transmissivities at six low-yielding (less than 0.5 gallon per minute) wells, which appear to lie within a poorly transmissive block of the bedrock, are consistently in a range of about 0.09 to 0.5 foot squared per day. The estimates of hydraulic conductivity and transmissivity in the southern half of the study area are supported by results of steady-state calibration of a numerical model and simulation of a 24-hour pumping test at a well completed in bedrock. Hydraulic conductivity values for the surficial aquifer used in the model were 30 feet per day for coarse-grained glaciomarine sediments, 0.001 to 0.01 foot per day for fine-grained glaciomarine sediments, and 0.1 to 0.5 foot per day for till. As part of model calibration, a relatively transmissive zone in the surficial aquifer was extended beyond the hypothesized extent of coarse-grained sediments eastward to the Dennys River. Hydraulic conductivity values used for bedrock in the model ranged from 3x10-4 to 1.5 feet per day. The highest values were in the fracture zone that hydraulically connects two wells and apparently extends to the Dennys River. The transmissivity of bedrock used in the model ranged from 0.03 to 150 feet squared per day, with the majority of the bedrock transmissivities set at 0.3 foot squared per day. Numerical modeling results indicated that a very low ratio of vertical hydraulic conductivity to thickness (1x10-9 days-l) was required to simulate a persistent cone of depression near a residential well that lies in the previously identified poorly transmissive block of bedrock.

Lyford, Forest P.; Garabedian, Stephen P.; Hansen, Bruce P.

1999-01-01

326

Sensitivity of simulated hydrological fluxes towards changes in soil properties in response to land use change  

NASA Astrophysics Data System (ADS)

Current model studies on the impact of land use change on water resources often simulate changes in land use without considering changes in the soil properties due to the change in land use. In this study, an artificial study catchment representing the Dill catchment (Germany) was used within the eco-hydrological model SWAT-G to study the sensitivity of SWAT-G simulations towards changes in soil properties during land use change. Since there is little information on these soil-vegetation interactions, we performed a model sensitivity study to investigate the impact of changes in the depth of the top soil layer, bulk density, saturated hydraulic conductivity and available water content on several simulated hydrological fluxes. To assess the significance of the simulated changes due to the changing soil properties, we compared the model sensitivity with the uncertainty in the hydrological fluxes due to the uncertainty in the parameterization of the plant parameters. The results showed that the changes in soil properties due to a land use transition from cropland to pasture only have a minor impact on the simulated mean annual, summer and winter runoff and actual evapotranspiration. Soil-vegetation interactions have a stronger impact on the simulated mean surface runoff, although the absolute contribution of this flux is small in our conceptualization of the Dill catchment. A comparison of the sensitivity and uncertainty of the simulated hydrological fluxes led to the conclusion that changes in soil properties due to land use change are relatively unimportant in our model of the Dill catchment in the light of the low sensitivity of the dominating hydrological fluxes and the large output uncertainty due to the plant parameter uncertainty.

Huisman, J. A.; Breuer, L.; Frede, H.-G.

327

Soil water infiltration measurements using electrical impedance tomography  

Microsoft Academic Search

Characterizing hydraulic properties of different types of soils is of great importance for agricultural and geological studies. In situ measurement of soil hydraulic conductivity is a time-consuming task since data has to be recorded at fixed time intervals over a period of minutes or hours depending on the type of soil. Moreover, it is still necessary to use real data

J. A. Gutiérrez Gnecchi; A. Gómez-Tagle Chávez; G. M. Chávez Campos; V. H. Olivares Peregrino; E. Marroquin Pineda

2010-01-01

328

Impact of Gypsum on Electromagnetic Properties of Desert Soils  

Microsoft Academic Search

Radar remote sensing of soil requires an under- standing about the electromagnetic properties of soils. Propaga- tion velocities and attenuation rates at ground-penetrating radar frequencies (0.25-4 GHz) were measured as a function of soil moisture content for soils from Iraq and Afghanistan. Soil sam- ples in the study include two with and two without gypsum (CaSO4 · 2H2O) as a

Gary Koh; Lillian D. Wakeley

2011-01-01

329

Saturated Hydraulic Conductivity of Semiarid Soils: Combined Effects of Salinity, Sodicity, and Rate of Wetting  

Microsoft Academic Search

als, high pH, and low sesquioxides content was found tobesusceptibletosodicconditions,withthemagnitude Combined effects of soil conditions (wetting rate), soil sodicity, of the decrease in HC being strongly dependent on the soil texture. The second experiment revealed that in the loamy sand been studied represented extreme conditions which do rate of wetting had no effect on the HC beyond that of sodicity

G. J. Levy; D. Goldstein; A. I. Mamedov

330

Prediction of Soil Fertility Properties from a Globally Distributed Soil Mid-Infrared Spectral Library  

Microsoft Academic Search

Globally applicable calibrations to predict standard soil properties based on infrared spectra may increase the use of this reliable technique. The objective of this study was to evaluate the ability of mid-infrared diffuse reflectance spectroscopy (4000-602 cm(-1)) to predict chemical and textural properties for a globally distributed soil spectral library. We scanned 971 soil samples selected from the International Soil

Thomas Terhoeven-Urselmans; Tor-Gunnar Vagen; Otto Spaargaren; Keith D. Shepherd

2010-01-01

331

Effect of treated domestic wastewater on soil physicochemical and microbiological properties.  

PubMed

A main concern with reuse of treated domestic wastewater (DWW) in irrigation is its possible effect on the soil. Few studies have focused on DWW treated in on-site settings, which generally use low-tech systems that can be constructed and serviced locally. One such system is the recirculating vertical flow constructed wetland (RVFCW). The aim of this study was to assess short- to midterm effects of irrigation with DWW treated in the RVFCW. Four groups of plastic barrels, filled with a sandy loam soil, were irrigated for 36 mo with fresh water (FW), FW with added fertilizer, raw DWW, or DWW treated in the RVFCW followed by ultraviolet disinfection. Principal component analysis revealed that the soil irrigated with treated DWW had physicochemical properties similar to those irrigated with FW amended with fertilizer. Levels of surfactants in soil irrigated with treated DWW were identical to those expected from standard irrigation practices, abating concerns for possible changes in soil hydraulic properties. was not detected in the soil irrigated with treated DWW, demonstrating the importance of disinfection of treated effluents before reuse in irrigation. Furthermore, irrigation with treated DWW did not alter the bacterial community structure according to terminal restriction fragment analysis. This 3-yr study suggests that the practice of irrigation with RVFCW effluents is safe. Continuation of the experiment is required to determine whether longer-term irrigation might show a different pattern. PMID:24216374

Sklarz, Menachem Y; Zhou, Meiyang; Ferrando Chavez, Diana L; Yakirevich, Alexander; Gillor, Osnat; Gross, Amit; Soares, M Ines M

2013-07-01

332

Physical properties and soil-water balance of key soils of the Opotiki region, North Island, New Zealand  

Microsoft Academic Search

The soil pattern of the Opotiki region consists of alluvial soils and soils derived from volcanic ash. The soils range from recent soils to gley soils and yellow-brown loams and are discussed in terms of soil physical properties and water balance. Levels of available water are generally high to very high except where root depth is restricted by high ground

W. C. Rijkse

1989-01-01

333

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

NASA Technical Reports Server (NTRS)

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

Carr, Stacy; Tsegaye, Teferi; Coleman, Tommy

1998-01-01

334

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

USGS Publications Warehouse

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

Kay, Robert T.; Earle, John D.

1990-01-01

335

First look at rock & soil properties  

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

336

Characterization of hydraulic fractures and reservoir properties of shale using natural tracers  

NASA Astrophysics Data System (ADS)

Hydraulic fracturing plays a major role in the economic production of hydrocarbon from shale. Current fracture characterization techniques are limited in diagnosing the transport properties of the fractures on the near wellbore scale to that of the entire stimulated reservoir volume. Microseismic reveals information on fracture geometries, but not transport properties. Production analysis (e.g., rate transient analysis using produced fluids) estimates fracture and reservoir flow characteristics, but often relies on simplified models in terms of fracture geometries and fluid storage and transport. We present the approach and potential benefits of incorporating natural tracers with production data analysis for fracture and reservoir characterization. Hydraulic fracturing releases omnipresent natural tracers that accumulate in low permeability rocks over geologic time (e.g., radiogenic 4He and 40Ar). Key reservoir characteristics govern the tracer release, which include: the number, connectivity, and geometry of fractures; the distribution of fracture-surface-area to matrix-block-volume; and the nature of hydrocarbon phases within the reservoir (e.g., methane dissolved in groundwater or present as a separate gas phase). We explore natural tracer systematics using numerical techniques under relevant shale-reservoir conditions. We evaluate the impact on natural tracer transport due to a variety of conceptual models of reservoir-transport properties and boundary conditions. Favorable attributes for analysis of natural tracers include the following: tracer concentrations start with a well-defined initial condition (i.e., equilibrium between matrix and any natural fractures); there is a large suite of tracers that cover a range of at least 7x in diffusion coefficients; and diffusive mass-transfer out of the matrix into hydraulic fractures will cause elemental and isotopic fractionation. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Heath, J. E.; Gardner, P.; Kuhlman, K. L.; Malama, B.

2013-12-01

337

Dielectric properties of salt-affected soils  

Microsoft Academic Search

A detailed laboratory experiment was conducted on three soils of different textures viz., sand, sandy clay loam and clay to study the influence of soil salinity and sodicity on the complex dielectric behaviour of soils as a function of volumetric soil moisture using an L-band (1 ·25 GHz) dielectric probe. The results revealed that soil salinity has no influence on

K. Sreenivas; L. Venkataratnam; P. V. Narasimha Rao

1995-01-01

338

The bulk hydraulic conductivity of mangrove soil perforated with animal burrows  

Microsoft Academic Search

Flow of groundwater from mangrove swamp sediment to mangrove creeks is likely to be an important pathway in mangrove swamps, particularly for the removal of salt excluded at the mangrove root. The swamps are generally saturated with water, and are perforated with animal burrows, allowing significant groundwater flow to mangrove creeks to occur. The hydraulic conductivity of the sediment is

Adi Susilo; Peter V. Ridd

2005-01-01

339

Device comprising detecting means for hydraulic or chemical-physical properties of a fluid  

US Patent & Trademark Office Database

A device has a body defining a space for the passage of a fluid, as well as a detector of a hydraulic or chemical-physical property of the fluid in the space. The detector is connected to a control unit by means of a wireless communication system that includes a data transmission circuit, connected to the detector, and a data receiving circuit, interfaced to the control unit. The wireless communication system includes a radio-frequency passive electric circuit without independent power supply.

2006-10-17

340

What happens to soil chemical properties after mangrove plants colonize?  

Microsoft Academic Search

Understanding soil chemical properties is necessary to characterize the basic properties of ecosystems. In mangrove ecosystems,\\u000a soil iron, phosphorus, methane and nitrogen have been well studied under field conditions. However, it is difficult to understand\\u000a fundamental relationships between mangrove root functions and soil chemical properties, because of the multiple factors present\\u000a in field data. The aim of this study was

Tomomi Inoue; Seiichi Nohara; Katsumi Matsumoto; Yasuharu Anzai

341

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

PubMed Central

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

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

2014-01-01

342

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

SciTech Connect

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.

Stephen L. Karner, Ph.D

2006-02-01

343

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

NASA Technical Reports Server (NTRS)

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

Kigel, J.; Cosgrove, D. J.

1991-01-01

344

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

Microsoft Academic Search

Rural areas represent approximately 95% of the 14000 km2 Alabama Black Belt, an area of widespread Vertisols dominated by clayey, smectitic, shrink–swell soils. These soils are unsuitable for conventional onsite wastewater treatment systems (OWTS) which are nevertheless widely used in this region. In order to provide an alternative wastewater dosing system, an experimental field moisture controlled subsurface drip irrigation (SDI) system

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

2011-01-01

345

The saturated hydraulic conductivity of soils with n-modal pore size distributions  

Microsoft Academic Search

A model for water retention in bi-modal soils (soils having structural and matrix porosity only) is further developed into a model for tri-modal soils so that the effects of macro-pores can also be included. This model is based on the exponential (Boltzmann) water retention function. It is suggested that this could be extended to include any number, n, of modes

A. R. Dexter; G. Richard

2009-01-01

346

Greywater reuse for irrigation: Effect on soil properties  

Microsoft Academic Search

A controlled study of the effect of greywater (GW) irrigation on soil properties was conducted. Containers of sand, loam and loess soils were planted with lettuce, and irrigated with fresh water, raw artificial GW or treated artificial GW. Greywater was treated using a recirculating vertical-flow constructed wetland. Soil samples were collected every 10days for the 40-day duration of the study,

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

2010-01-01

347

Properties of soil organic matter and aqueous extracts of actually water repellent and wettable soil samples  

Microsoft Academic Search

The occurrence of water repellent spots can inhibit a homogeneous wetting progress in soil. Although the wettability is an important factor for sorption and transport processes, the knowledge about the reasons for water repellent behavior and its effects on other soil properties is still insufficient. In this study, water repellent and wettable soil samples from two urban locations were compared.

Julia Hurraß; Gabriele E. Schaumann

2006-01-01

348

Soybean Root Distribution Related to Claypan Soil Properties and Apparent Soil Electrical Conductivity  

Microsoft Academic Search

Soybean (Glycine max (L.) Merr.) yield in claypan soils varies systematically with soil properties and landscape position. This is likely caused by soil interactions with soybean roots. Field obser- vations of soybean root distribution are needed to reveal its effect on yield variability. This study examined profi le distributions of soybean root length density (RLD) and average root diameter (ARD)

D. Brenton Myers; Newell R. Kitchen; Kenneth A. Sudduth; Robert E. Sharp; Randall J. Miles

2007-01-01

349

Effects of soil properties and trace metals on urease activities of calcareous soils  

Microsoft Academic Search

A study was conducted to investigate the relationship between urease activity and some physical, chemical, and microbiological properties of soils from central Iran. Inhibitory effects of Cr, Cd, and Pb on urease activity were also studied. Results indicated that no significant difference was observed between urease activity of field-moist and air-dried soils. Soil organic C and total N correlated highly

Farshid Nourbakhsh; Carlos M. Monreal

2004-01-01

350

The Effects of the Physical and Chemical Properties of Soils on the Spectral Reflectance of Soils  

Microsoft Academic Search

Many attempts have been made to use multispectral data to map soils on the basis of soil color, texture, organic matter content, moisture content, and free iron oxides. Researchers have endeavored to differentiate soil series and coil types, using those parameters individually. Reflective properties have been attributed primarily to one or two of these parameters. Little has been revealed as

O. L. Montgomery; M. F. Baumgardner

1974-01-01

351

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

Microsoft Academic Search

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

Darren Drewry; Praveen Kumar; Murugesu Sivapalan

2010-01-01

352

Prediction of the saturated hydraulic conductivity from Brooks and Corey's water retention parameters  

NASA Astrophysics Data System (ADS)

Prediction of flow through variably saturated porous media requires accurate knowledge of the soil hydraulic properties, namely the water retention function (WRF) and the hydraulic conductivity function (HCF). Unfortunately, direct measurement of the HCF is time consuming and expensive. In this study, we derive a simple closed-form equation that predicts the saturated hydraulic conductivity, Ks from the WRF parameters of Brooks and Corey (1964). This physically based analytical expression uses an empirical tortuosity parameter (?) and exploits the information embedded in the measured pore-size distribution. Our proposed model is compared against the current state of the art using more than 250 soil samples from the Grenoble soil catalog (GRIZZLY) and hydraulic properties of European soils (HYPRES) databases. Results demonstrate that the proposed model provides better predictions of the saturated hydraulic conductivity values with reduced size of the 90% confidence intervals of about 3 orders of magnitude.

Nasta, Paolo; Vrugt, Jasper A.; Romano, Nunzio

2013-05-01

353

Soil properties influencing the denitrification potential of Flemish agricultural soils  

Microsoft Academic Search

The denitrification potential of the soil horizons between 0- and 90-cm depth of 20 agricultural fields, representative of the most frequent combinations of agricultural crops and soil textures in Flanders (Belgium), and the factors affecting the denitrification potential were studied in the laboratory under controlled conditions. The denitrification potential in the presence of an added soluble C and N source

Karoline D'Haene; Edwin Moreels; Stefaan De Neve; Barbara Chaves Daguilar; Pascal Boeckx; Georges Hofman; Oswald Van Cleemput

2003-01-01

354

System identification estimation of soil properties at the Lotung site  

Microsoft Academic Search

Dynamic properties of the soils at the Lotung test site, Lotung, Taiwan, are estimated from seismic vertical array measurements (input–output data sets) using both time-invariant and time-variant parametric modeling methods (system identification). Soil properties are directly mapped from model parameters to an equivalent lumped mass model of the soil interval. Shear stiffness and damping ratios were calculated for 8 events

S. D. Glaser; L. G. Baise

2000-01-01

355

Inverse modeling of the hydraulic properties of fractured media : development of a flow tomography approach  

NASA Astrophysics Data System (ADS)

Inverse modeling of hydraulic and geometrical properties of fractured media is a very challenging objective due to the spatial heterogeneity of the medium and the scarcity of data. Here we present a flow tomography approach that permits to characterize the location, the connectivity and the hydraulic properties of main flow paths in fractured media. The accurate characterization of the location, hydraulic properties and connectivity of major fracture zones is essential to model flow and solute transport in fractured media. Cross-borehole flowmeter tests, which consist of measuring changes in vertical borehole flows when pumping a neighboring borehole, were shown to be an efficient technique to provide information on the properties of the flow zones that connect borehole pairs [Paillet, 1998; Le Borgne et al., 2006]. The interpretation of such experiments may however be quite uncertain when multiple connections exist. In this study, we explore the potential of flow tomography (i.e., sequential cross-borehole flowmeter tests) for characterizing aquifer heterogeneity. We first propose a framework for inverting flow and drawdown data to infer fracture connectivity and transmissivities. Here we use a simplified discrete fracture network approach that highlights main connectivity structures. This conceptual model attempts to reproduce fracture network connectivity without taking fracture geometry (length, orientation, dip) into account. We then explore the potential of the method for simplified synthetic fracture network models and quantify the sensitivity of drawdown and borehole flow velocities to the transmissivity of the connecting flowpaths. Flow tomography is expected to be most effective if cross-borehole pumping induces large changes in vertical borehole velocities. The uncertainty of the transmissivity estimates increases for small borehole flow velocities. The uncertainty about the transmissivity of fractures that connect the main flowpath but not the boreholes is generally higher. We demonstrate that successively changing pumping and observation boreholes improves the quality of available information and reduces the indetermination of the problem. The inverse method is validated for different synthetic flow scenarios. It is shown to provide a good estimation of connectivity patterns and transmissivities of main flowpaths. Although the chosen fracture network geometry has been simplified, flow tomography appears to be a promising approach for characterizing connectivity patterns and transmissivities of fractured media.

Bour, O.; Klepikova, M.; Le Borgne, T.; De Dreuzy, J.

2013-12-01

356

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

NASA Astrophysics Data System (ADS)

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).

Zhang, M.; Takeda, M.

2007-12-01

357

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

Microsoft Academic Search

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

Albright

1995-01-01

358

Comparison of soil properties between continuously cultivated and adjacent uncultivated soils in rice-based systems  

Microsoft Academic Search

To assess cultivation-induced changes followed during the Green Revolution on continuous rice–rice and rice–wheat cropping,\\u000a fence-line comparisons between cultivated and adjacent noncultivated soils were made to (a) quantify changes in selected soil\\u000a chemical and biological properties at two moisture conditions, (b) determine the N, P, and K uptake of rice and wheat as affected\\u000a by changes in soil properties, and

Crisanta S. Bueno; J. K. Ladha

2009-01-01

359

Hydraulic Drives of Aircraft. Part I.  

National Technical Information Service (NTIS)

Contents: The place occupied by hydraulic systems in equipment of aircraft; Working fluids and their properties; Basic information on hydraulics of pipelines; Pumps and hydraulic motors; Pumps and hydraulic motors of piston types; Axial-piston pumps and h...

T. M. Bashta

1969-01-01

360

Phosphorus sorption in relation to soil properties in some cultivated Swedish soils  

Microsoft Academic Search

Phosphorus (P) sorption properties are poorly documented for Swedish soils. In this study, P sorption capacity and its relation to soil properties were determined and evaluated in 10 representative Swedish topsoils depleted in available P. P sorption indices were estimated from sorption isotherms using Langmuir and Freundlich equations (Xm and aF, respectively) and P buffering capacity (PBC). Xm ranged from

Katarina Börling; Erasmus Otabbong; Elisabetta Barberis

2001-01-01

361

Hydrological properties of natural and reconstituted soils: compared methods.  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

362

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

NASA Astrophysics Data System (ADS)

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