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1

Land Use Effects on Soil Hydraulic Properties  

Microsoft Academic Search

Tillage alters the pore structure and hydraulic properties of soils. Likewise, reestablishment of grass on cropland will, over time, produce changes in soil hydraulic properties that can influence the amount of plant available water. We conducted a study to characterize and compare soil hydraulic properties on adjacent native grassland, cropland, and Conservation Reserve Program (CRP) sites at three locations in

R. C. Schwartz; P. W. Unger; S. R. Evett

2

BOREAS HYD-1 Soil Hydraulic Properties  

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

3

Scaling hydraulic properties of a macroporous soil Binayak P. Mohanty  

E-print Network

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

Mohanty, Binayak P.

4

Soil Texture Triangle: Hydraulic Properties Calculator  

NSDL National Science Digital Library

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

Saxton, Keith E., 1937-

5

Spatial variability of the hydraulic properties of a volcanic soil  

Microsoft Academic Search

The spatial variability of soil properties in a typical volcanic Vesuvian soil was investigated by collecting undisturbed soil samples at equal intervals of 1.5 m along a 135 m transect at a depth of 0.45 m. In this study, the spatial structure of soil hydraulic properties was examined using both statistical and geostatistical concepts. Soil hydraulic properties were determined in

G. Ciollaro; N. Romano

1995-01-01

6

Determination of soil hydraulic properties using the soil pedostructure concept  

NASA Astrophysics Data System (ADS)

The observed soil water properties such as Field Capacity, Permanent Wilting Point, Water Potential and Hydraulic Conductivity are expressions of the internal soil structure and are all connected to Water Matric Potential. Our research describes these properties in a context of a new concept of the internal hierarchal soil structure and the tension that exists inside the soil matrix due to the presence of clay particles. This concept will be demonstrated using laboratory experiments of simultaneous and continuous measurements of the soil water potential curve and of the shrinkage and swelling curves. The soil shrinkage curve has been used to explain the hydraulic and functional properties of soil with its assembly of swelling aggregates according to the conceptual pedostructure model. In that model two water pools held in two distinguished macro- and micro-porosity are described in addition to specific characteristics of the primary peds such air entry point, maximum swelling, and plasmic porosity. The water potential will be calculated according to these water pools. In this context, the empirical agronomical soil physical properties like wilting point and field capacity, will be defined relative to a particular hydrostructural state of the soil rather than to a hypothetical soil water potential. These properties could then be accurately determined starting from the measured shrinkage curve determined by retractometry.

Braudeau, E.; Mohtar, R. H.

2003-04-01

7

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

8

Effect of spatial soil hydraulic properties on large scale evapotranspiration  

NASA Astrophysics Data System (ADS)

This study investigates the effects of different under shrub and interspace soil hydraulic property characteristics on hydrological processes, typical of desert environments. Spatial structure of soils and hydraulic properties of interspersed bare soil and shrub is important in understanding large scale hydrological processes important to the environments and ecosystems. The impact on the large scale evapotranspiration of spatial variability of shrub coverage is investigated with different ranges of shrub coverage and correlation lengths of the shrub distributions. Two fields for the soil hydraulic parameters are generated based on distinct statistics for the under shrub and interspace soil hydraulic properties. These two fields are integrated into complete spatial distribution for the soil hydraulic parameters of large scale field. The hydrological process is then simulated at the local scale and then aggregated to represent large scale evaporation and transpiration. Results demonstrate that spatial variability of soil hydraulic properties affects water partition at small scale. The ratio of shrub transpiration and total evapotranspiration at large scale increases between precipitation events and slightly drops immediately after rain. It indicates evaporation in interspace and shrub transpiration have different temporal scales.

Zhu, J.; Sun, D.

2009-05-01

9

Effective unsaturated hydraulic properties of heterogeneous soil structures  

Microsoft Academic Search

Inverse modeling of transient flow experiments is becoming an increasingly used method to determine effective hydraulic properties of soil bodies. The basic requirements on the experimental procedures and on type and quality of data that are needed to obtain accurate and reliable estimates of the hydraulic parameters are now well known. If, despite proper experimental procedures, the inverse analysis fails,

W. Durner; K. Foit; C. Beyer; S. Iden; K. Schulz

2003-01-01

10

The effect of soil hydraulic properties vs. soil texture in land surface models  

E-print Network

The effect of soil hydraulic properties vs. soil texture in land surface models E. D. Gutmann and E to determine SHPs. Citation: Gutmann, E. D., and E. E. Small (2005), The effect of soil hydraulic properties vs), thus controlling how water moves through the soil. This movement controls the water balance parti

Small, Eric

11

IRRIGATION IN A VARIABLE LANDSCAPE: SOIL HYDRAULIC PROPERTIES INFORMATION AND ITS APPLICATION  

Microsoft Academic Search

The Shepparton Irrigation Region (SIR) has a wide range of soil types and soil hydraulic properties are spatially variable throughout the landscape. The performance of any irrigation system is highly dependent on the soil characteristics, in particular the soil hydraulic properties. However, knowledge of soil hydraulic properties is very limited for the SIR and the existing soil maps do not

Brijesh Mehta; QJ Wang

12

Variation of Desert Soil Hydraulic Properties with Pedogenic Maturity  

NASA Astrophysics Data System (ADS)

Older alluvial desert soils exhibit greater pedogenic maturity, having more distinct desert pavements, vesicular (Av) horizons, and more pronounced stratification from processes such as illuviation and salt accumulation. These and related effects strongly influence the soil hydraulic properties. Older soils have been observed to have lower saturated hydraulic conductivity, and possibly greater capacity to retain water, but the quantitative effect of specific pedogenic features on the soil water retention or unsaturated hydraulic conductivity (K) curves is poorly known. With field infiltration/redistribution experiments on three different-aged soils developed within alluvial wash deposits in the Mojave National Preserve, we evaluated effective hydraulic properties over a scale of several m horizontally and to 1.5 m depth. We then correlated these properties with pedogenic features. The selected soils are (1) recently deposited sediments, (2) a soil of early Holocene age, and (3) a highly developed soil of late Pleistocene age. In each experiment we ponded water in a 1-m-diameter infiltration ring for 2.3 hr. For several weeks we monitored subsurface water content and matric pressure using surface electrical resistance imaging, dielectric-constant probes, heat-dissipation probes, and tensiometers. Analysis of these data using an inverse modeling technique gives the water retention and K properties needed for predictive modeling. Some properties show a consistent trend with soil age. Progressively more developed surface and near-surface features such as desert pavement and Av horizons are the likely cause of an observed consistent decline of infiltration capacity with soil age. Other properties, such as vertical flow retardation by layer contrasts, appear to have a more complicated soil-age dependence. The wash deposits display distinct depositional layering that has a retarding effect on vertical flow, an effect that may be less pronounced in the older Holocene soil, where the original depositional structure has a relatively modest influence. Anisotropy at the scale of centimeters is of major importance in the Pleistocene soil, with developed horizons that tend to hold water within about 0.5 m of the surface for a longer duration than in the two younger soils. Correlation of these and related pedogenic features with soil hydraulic properties is a first step toward the estimation of effective hydraulic properties of widely varying Mojave Desert soils, as needed for large-scale evaluation of soil moisture dynamics in relation to ecological habitat quality.

Nimmo, J. R.; Perkins, K. S.; Mirus, B. B.; Schmidt, K. M.; Miller, D. M.; Stock, J. D.; Singha, K.

2006-12-01

13

Simplified evaporation method for determining soil hydraulic properties  

Microsoft Academic Search

Summary Evaporation experiments are commonly used to derive hydraulic properties of soils. In the simplified evaporation method, as proposed by Schindler (Schindler, U., 1980. Ein Schnellverfahren zur Messung der Wasserleitfahigkeit im teilgesattigten Boden an Ste- chzylinderproben. Arch. Acker- u. Pflanzenbau u. Bodenkd. Berlin 24, 1-7), the weight of a soil sample and pressure heads at two height levels are recorded

A. Peters; W. Durner

2008-01-01

14

Tillage Effects on Hydraulic Properties and Macroporosity in Silty and Sandy Soils  

Microsoft Academic Search

In agricultural soils, macroporosity and hydraulic properties are influenced by tillage practices. The objective of this study was to characterize macroporosity and surface soil hydraulic properties in two soils of different texture (Lietzen: sandy loam-Humic Dystrudept; Adenstedt: silt loam; Typic Hapludoll) under conventional (CT) and conservational (RT) tillage systems. Soil hydraulic conductivity was assessed in situ by ponded infiltration with

U. Buczko; O. Bens; R. F. Hüttl

2006-01-01

15

Upscaling of soil hydraulic properties for steady state evaporation and infiltration  

E-print Network

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

Mohanty, Binayak P.

16

Estimation of Soil Hydraulic Properties from Numerical Inversion of Tension Disk Infiltrometer Data  

Microsoft Academic Search

Many applications involving variably saturated flow and transport require estimates of the unsaturated soil hydraulic properties. Nu- merical inversion of cumulative infiltration data during transient flow, complemented with initial or final soil water content data, is an in- creasinglypopular approach for estimating the hydraulic curves. In this study, we compared Mualem-van Genuchten (MVG) soil hydraulic parameters obtained from direct laboratory

T. B. Ramos; M. C. Gonçalves; J. C. Martins; M. Th. van Genuchten; F. P. Pires

2006-01-01

17

Spatial Association among Soil Hydraulic Properties, Soil Texture, and Geoelectrical Resistivity  

Microsoft Academic Search

Spatial variability of soil hydraulic properties causes considerable variations in water and solute flow and transport processes. It remains a difficult task to determine and describe the spatial pattern of soil physical properties for modeling landscape-scale vadose zone pro- cesses. Strategies that involve measurements of relevant variables and appropriate spatial modeling tools need to be identified for this pur- pose.

Ole Wendroth; Sylvia Koszinski; Eugenia Pena-Yewtukhiv

2006-01-01

18

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

19

Hydraulic Properties in a Silt Loam Soil under Natural Prairie, Conventional Till, and No-Till  

Microsoft Academic Search

undergo this dramatic cyclic change in soil structure; although seasonal variations in hydraulic conductivities Tillage in the Palouse region of Washington State over the past occur through root development, earthworm activity, 100 yr has influenced the soil physical and biological properties. In particular, hydraulic properties are significantly affected by soil culti- and other natural processes such as freezing and thaw-

Juan P. Fuentes; Markus Flury; David F. Bezdicek

2004-01-01

20

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

21

Climatic controls on soil hydraulic properties along soil chronosequences on volcanic parent material  

NASA Astrophysics Data System (ADS)

Soil development is influenced by physical and chemical weathering processes and accumulation of eolian sediment. These weathering processes have often been examined using chronosequences that take advantage of deposited lava flows ranging in age. These studies typically characterize the physical and sometimes chemical properties, but rarely have these studies examined how hydraulic properties change with time. In addition, many of these studies occur in tropical climates where weathering occurs rapidly; relatively little is known about weathering processes in cool dry climates. This is important not only to understand how water and energy move in these water limited systems, but also to understand how they might change as climate patterns shift. The objectives of this research were to 1) measure and model the soil water retention, ?(h), and hydraulic conductivity, K(h), functions across a chronosequence of cinder cone sites in a cold desert region, 2) compare soil hydraulic properties across soil ages to examine how soil development in semi-arid climates moderates soil hydraulic processes, and 3) compare soil hydraulic characteristics in a dryland environment to those of a wet tropical climate across similarly aged lava flows. We contrast 2.1, 6.9 and 13.9 ka cinder cones soils at Craters of the Moon (COTM) National Monument, Idaho, USA. Soil development at COTM is sparse and is concentrated in joints and crevices of the basalt. The soils contrast slightly in texture with age. The young (2.1 ka) soils are coarser grained with at least 20% greater sand content than the older (6.9, 13.9 ka) soils. Preliminary hydraulic modeling suggests that older soils have lower ? values than younger soils. This is likely due to a higher bulk density values from higher accumulations of secondary minerals in the old soils from loess input. The models show that the air entry points (?) occur at lower tensions in the young soils, likely caused by a greater pore size distribution. We observe that ? decreases with age, and ? occurs at higher tensions. Soil horizons are developed dominantly on the cinder cones. These model estimates appear to match well with preliminary field measurements. Tropical climates enhance the weathering of basaltic parent material. The mean annual precipitation in the Hawaiian site is 2500 mm, and 310 mm at COTM. Accumulation of rainfall increases the weathering rate of the parent material. Using previous work characterizing the physical characteristics of soil across the Hawaii chronosequence to model the contrasting soils, we found that the 0.3 and 20 ka Hawaii soils had similar hydraulic properties; ? values were approximately 0.45 cm3/cm3 and Ks values were 6 cm/hr. However, these Hawaiian soils contrasted and were quantitatively lower than the entire COTM chronosequence. At the 2.1 ka COTM soil, Ks was 17 cm/hr and ? was 0.52-0.65 cm3/cm3 whereas at the 13.9 ka soil, Ks was 12 cm/hr and ? was 0.52 cm3/cm3. The 0.3 ka Hawaiian soil had a 20-30% higher silt content than the 2.1 ka COTM soil. Our models help quantify rates of soil development and hydraulic properties developed through time on volcanic parent materials.

Beal, L. K.; Lohse, K. A.; Godsey, S.; Huber, D. P.

2013-12-01

22

Effects of Soil Morphology on Hydraulic Properties: II. Hydraulic Pedotransfer Functions  

Microsoft Academic Search

years as an approach to translate simple soil characteristics found in soil surveys into more complicated model input parameters. However, However, existing pedotransfer functions have not yet existing pedotransfer functions have not yet incorporated critical soil incorporated critical soil structural information such as structural information. This study showed that soil hydraulic proper- pedality and macroporosity. This, in part, may be

H. S. Lin; K. J. McInnes; L. P. Wilding; C. T. Hallmark

23

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

Microsoft Academic Search

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

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

1999-01-01

24

Soil hydraulic properties of cropland compared with reestablished and native grassland  

Microsoft Academic Search

Conversion of cropland to perennial grasses will, over time, produce changes in soil hydraulic properties. The objective of this study was to characterize and compare hydraulic properties of fine-textured soils on adjacent native grassland, recently tilled cropland, and reestablished grassland in the Conservation Reserve Program (CRP) at three locations in the Southern Great Plains. A tension infiltrometer was used to

Robert C. Schwartz; Steven R. Evett; Paul W. Unger

2003-01-01

25

Hydraulic and Physical Properties of Stony Soils in a Small Watershed  

Microsoft Academic Search

creased forage production and stocking rates of grazing livestock. Concentrated animal agriculture and land ap- The presence of rock fragments in soil layers can have a profound plication of animal manures have increased concerns impact on measured hydraulic properties. Variation of surface soil hydraulic properties influences the amount, distribution, and routing regarding nutrient loads in runoff and accelerated eutro- of

Thomas J. Sauer; Sally D. Logsdon

2002-01-01

26

Estimating Vadose Zone Hydraulic Properties of Artificially Drained Fields Using Irrigation District and Soil Survey Data  

Microsoft Academic Search

The prediction of water flow and solute transport through the vadose zone requires knowledge of the spatial distribution of soil hydraulic properties, such as the conductivity and retention parameters. Several point-scale techniques are available for measuring soil hydraulic properties. However, in applications at the field to regional scale, a prohibitively large number of sampling sites are needed to characterize the

G. Schoups; C. Young; J. Hopmans; W. Wallender; G. Fogg; K. Tanji; T. Harter; T. Hsiao; S. Ustin; K. Ward; R. Howitt

2001-01-01

27

Variation of Surficial Soil Hydraulic Properties Across Land Uses in the Southern Blue Ridge Mountains  

Microsoft Academic Search

Soil hydraulic properties have been shown to affect watershed hydrology by influencing pathways and transmission rates of precipitation to stream networks, and human land use has been shown to influence these soil properties. Particle size distribution, saturated hydraulic conductivity, bulk density, and water holding capacity were measured at 90 points (30 points in each land use category of forest, lawn,

K. Price; C. R. Jackson; A. J. Parker

2008-01-01

28

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. PMID:24748683

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

2013-01-01

29

Data of hydraulic properties of North East and Central German soils  

Microsoft Academic Search

The paper presents a data base of soil hydrological properties of North East and Central German soils. Included are measured data of the soil water retention curve and the unsaturated hydraulic conductivity function. Information to geo reference, soil type and horizon are given. Additional soil physical data like particle size distribution, dry bulk density, organic matter content and other variables

U. Schindler; L. Müller

2010-01-01

30

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

Microsoft Academic Search

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

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

2007-01-01

31

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

E-print Network

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

Kumar, C.P.

32

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

33

Treated wastewater effects on water repellency and soil hydraulic properties of soil aquifer treatment infiltration basins  

NASA Astrophysics Data System (ADS)

SummaryIrrigation with treated wastewater (TWW) has been reported to induce low to moderate hydrophobicity in soils of different texture with or without vegetation cover. Additional potential sites for adverse effects of TWW are infiltration basins, where TWW undergoes tertiary treatment, known as soil aquifer treatment (SAT). The annual organic matter (OM) loads in SAT are a hundred fold higher than those applied in irrigation with TWW. Therefore, we initially presumed that in the sandy soils of SAT infiltration basins, hydrophobicity would be expressed to a higher extent and would further affect the hydraulic properties of these soils. This hypothesis was tested in the Dan Region Wastewater Reclamation Project, Tel-Aviv, Israel. In terms of water drop penetration time (WDPT) test, the results obtained exhibited similar hydrophobicity levels (0 ? WDPT ? 238 s) to those obtained in the TWW irrigated fields and in a similar manner, soil hydrophobicity was only exhibited in the surface soil layer. It is suggested that the low to moderate hydrophobicity obtained under TWW irrigation and recharge into the SAT basins, may primarily stem from the drying and wetting cycle regimes employed. Under these conditions, hydrophobic compounds, which may impart hydrophobicity to the soil particles, are likely to detach and dissolve into the soil solution at the subsequent irrigation or recharge event. Furthermore, the frequent displacement of the resident TWW derived OM by repeatedly flooding events, prevents maturation and humification of the resident OM. Further investigations on the hydraulic properties of the basin soils were conducted in conjunction with the solid-liquid contact angle ( ?) and the surface tension ( ?L) of the soil solution. The results obtained imply that the dependence of the hydraulic properties on ? and/or ?L, can be attributed to the hydrophobic nature of both the solid and dissolved OM originating from the recharged TWW.

Arye, Gilboa; Tarchitzky, Jorge; Chen, Yona

2011-01-01

34

Determination of unsaturated soil hydraulic properties at different applied tensions and water qualities  

Microsoft Academic Search

Irrigation with low-quality water may change soil hydraulic properties due to excessive electrical conductivity (ECw) and sodium adsorption ratio (SARw). Field experiments were conducted to determine the effects of water quality (ECw of 0.5–20 dS m and SARw of 0.5–40 mol l) on the hydraulic properties of a sandy clay loam soil (containing ?421 g gravel kg soil) at applied tensions of 0–0.2 m.

Ali Akbar Moosavi; Ali Reza Sepaskhah

2012-01-01

35

Determination of unsaturated soil hydraulic properties at different applied tensions and water qualities  

Microsoft Academic Search

Irrigation with low-quality water may change soil hydraulic properties due to excessive electrical conductivity (ECw) and sodium adsorption ratio (SARw). Field experiments were conducted to determine the effects of water quality (ECw of 0.5–20 dS m and SARw of 0.5–40 mol l) on the hydraulic properties of a sandy clay loam soil (containing ?421 g gravel kg soil) at applied tensions of 0–0.2 m.

Ali Akbar Moosavi; Ali Reza Sepaskhah

2011-01-01

36

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

37

Infiltration during soil sealing: The effect of areal heterogeneity of soil hydraulic properties  

NASA Astrophysics Data System (ADS)

The combined effects of soil surface sealing and areal heterogeneity of the soil hydraulic properties on the mean infiltration curve are studied here for the first time. Seal formation during rainfall is simulated according to the dynamic model of [1997]. Areal heterogeneity is represented by lognormal distribution of the saturated hydraulic conductivity of the initially undisturbed soil and by related distributions of the other soil parameters. The mean infiltration curve of the heterogeneous field is evaluated presuming that horizontal fluxes are negligible. It is found that when soil surface sealing is taken into account in a heterogeneous field, the ponding time is only slightly affected. However, significantly more runoff is produced compared to nonsealing field (mulched), with the relative area contributing to surface runoff being increased from 65 to 95%. The relative effect of field heterogeneity on the infiltration curve increases for higher rainfall intensity. The formation of soil surface seal apparently reduces the effect of the field areal variability on the steady infiltration rate. The infiltration rate after 60 min of rainfall distributes lognormally under sealing conditions, while it distributes normally in the case of the unsealed soil. The final infiltration rate resulting from the assumption of a sealed uniform field is underestimated compared to sealed heterogeneous field, with the relative effect being larger for a loam soil (-51%) than for a sandy loam soil (-26%). Also, the approximation that the infiltration curve is a unique function of cumulative rainfall independent of rainfall intensity is not valid in a sealing heterogeneous field, and its application in such a case would be more erroneous than in uniform fields. On the other hand, one may disregard the variability of all soil parameters, except the hydraulic conductivity, when calculating infiltration.

Assouline, S.; Mualem, Y.

2002-12-01

38

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

39

Sensitivity of rainfall excess to antecedent soil moisture and soil hydraulic properties  

NASA Technical Reports Server (NTRS)

A sensitivity analysis to determine the impact of antecedent soil moisture and soil hydraulic properties on rainfall excess volumes was performed. That the spatial distribution of surface soil moisture at the beginning of a storm must be correctly defined if physically-based hydrologic models are to properly partition the rainfall into portions that enter the soil and portions that become available for surface runoff. This statement is especially true for those rainfall events that occur on a routine or frequent basis. Thus, the quality of the results of continuous accounting models used to estimate the replenishment of foil moisture storage from rainfall are closely tied to the quality of information on the soil moisture in the surface layers at the beginning of the storm event.

Wilkening, H. A.

1982-01-01

40

Dynamics of soil hydraulic properties during fallow as affected by tillage  

Microsoft Academic Search

There is limited information on the effects of tillage practices on soil hydraulic properties, especially changes with time. The objective of this study was to evaluate on a long-term field experiment the influence of conventional tillage (CT), reduced tillage (RT) and no-tillage (NT) on the dynamics of soil hydraulic properties over 3 consecutive 16–18 month fallow periods. Surface measurements of

D. Moret; J. L. Arrúe

2007-01-01

41

Estimating Vadose Zone Hydraulic Properties of Artificially Drained Fields Using Irrigation District and Soil Survey Data  

NASA Astrophysics Data System (ADS)

The prediction of water flow and solute transport through the vadose zone requires knowledge of the spatial distribution of soil hydraulic properties, such as the conductivity and retention parameters. Several point-scale techniques are available for measuring soil hydraulic properties. However, in applications at the field to regional scale, a prohibitively large number of sampling sites are needed to characterize the vadose zone. Therefore, an alternative approach is presented here, using readily available data. The method is applied to the estimation of the spatial distribution of soil hydraulic properties for a 4000 ha irrigation district located in the San Joaquin Valley, California, using two sources of data. First, the SSURGO soil survey dataset currently provides the most detailed information on the spatial distribution of soil types. Unfortunately, the data provided by the survey cannot directly be used in subsurface modeling efforts. Soil textural information from the survey must be converted to soil hydraulic parameters used by hydrologic models. Pedo-transfer functions are used to provide an estimated range for the soil hydraulic parameters based on the soil textural data in the soil survey. The second piece of data is available from the irrigation district and consists of irrigation applications, crop patterns, and tile drain flows at the field scale. These data are used to estimate soil hydraulic parameters by inverse modeling of tile drain flows with a variably saturated flow model and an efficient global optimization algorithm. This procedure consists of automatically adjusting soil hydraulic parameters until observed tile drain flows are reproduced. The parameter ranges estimated from the soil survey data and the pedo-transfer functions are used to constrain the parameter values in the optimization procedure.

Schoups, G.; Young, C.; Hopmans, J.; Wallender, W.; Fogg, G.; Tanji, K.; Harter, T.; Hsiao, T.; Ustin, S.; Ward, K.; Howitt, R.

2001-12-01

42

Environmental and management impacts on temporal variability of soil hydraulic properties  

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

43

Impact of land management on soil structure and soil hydraulic properties  

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

44

Soil hydraulic properties influenced by corn stover removal from no-till corn in Ohio  

Microsoft Academic Search

Corn (Zea mays L.) stover removal for biofuel production and other uses may alter soil hydraulic properties, but site-specific information needed to determine the threshold levels of removal for the U.S. Corn Belt region is limited. This study quantified impacts of systematic removal of corn stover on soil hydraulic parameters after 1 year of stover management under no-till (NT) systems.

Humberto Blanco-Canqui; Rattan Lal; W. M. Post; R Cesar C. Izaurralde; M. J. Shipitalo

2007-01-01

45

Spatial analysis of soil surface hydraulic properties: Is infiltration method dependent?  

Microsoft Academic Search

The management of irrigated agricultural fields requires reliable information about soil hydraulic properties and their spatio-temporal variability. The spatial variability of saturated hydraulic conductivity, Ks and the alpha-parameter ?vG-2007 of the van Genuchten equation was reviewed on an agricultural loamy soil after a 17-year period of repeated conventional agricultural practices for tillage and planting. The Beerkan infiltration method and its

Ibrahim Mubarak; Rafael Angulo-Jaramillo; Jean Claude Mailhol; Pierre Ruelle; Mohammadreza Khaledian; Michel Vauclin

2010-01-01

46

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

47

Ant burrow effects on water flow and soil hydraulic properties of Sparta sand  

Microsoft Academic Search

Macropores generally have a significant influence on soil hydrologic processes. Ants create large burrows that may function as macropores, thus creating a potential for rapid movement of water and water-soluble chemicals in soil. This study was conducted to characterize the impact of ant burrows on hydraulic properties of a Sparta sand (uncoated, mesic Typic Quartzipsamments), and to determine the potential

D. Wang; B. Lowery; J. M. Norman; K. McSweeney

1996-01-01

48

Tension Disk Infiltrometry to Determine Hydraulic Properties of Coarse Textured Soils on Granites of the Sila Massif (Italy)  

Microsoft Academic Search

The potential for groundwater contamination at a given location is influenced strongly by the hydraulic properties of soils. The application of numerical models of soil water flow and solute transport is important for efficient resource management and maintenance of environmental quality. The non-availability of hydraulic properties data for most soils is the obstacle to be overcome for general application of

Gabriele Buttafuoco; Nicola Ricca

49

Uncertainty in predicting soil hydraulic properties at the hillslope scale with indirect methods  

NASA Astrophysics Data System (ADS)

SummarySeveral hydrological applications require the characterisation of the soil hydraulic properties at large spatial scales. Pedotransfer functions (PTFs) are being developed as simplified methods to estimate soil hydraulic properties as an alternative to direct measurements, which are unfeasible for most practical circumstances. The objective of this study is to quantify the uncertainty in PTFs spatial predictions at the hillslope scale as related to the sampling density, due to: (i) the error in estimated soil physico-chemical properties and (ii) PTF model error. The analysis is carried out on a 2-km-long experimental hillslope in South Italy. The method adopted is based on a stochastic generation of patterns of soil variables using sequential Gaussian simulation, conditioned to the observed sample data. The following PTFs are applied: Vereecken's PTF [Vereecken, H., Diels, J., van Orshoven, J., Feyen, J., Bouma, J., 1992. Functional evaluation of pedotransfer functions for the estimation of soil hydraulic properties. Soil Sci. Soc. Am. J. 56, 1371-1378] and HYPRES PTF [Wösten, J.H.M., Lilly, A., Nemes, A., Le Bas, C., 1999. Development and use of a database of hydraulic properties of European soils. Geoderma 90, 169-185]. The two PTFs estimate reliably the soil water retention characteristic even for a relatively coarse sampling resolution, with prediction uncertainties comparable to the uncertainties in direct laboratory or field measurements. The uncertainty of soil water retention prediction due to the model error is as much as or more significant than the uncertainty associated with the estimated input, even for a relatively coarse sampling resolution. Prediction uncertainties are much more important when PTF are applied to estimate the saturated hydraulic conductivity. In this case model error dominates the overall prediction uncertainties, making negligible the effect of the input error.

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

2007-02-01

50

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

51

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

52

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

53

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

54

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

55

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

56

Parameter estimation of unsaturated soil hydraulic properties from transient flow processes1  

Microsoft Academic Search

Three field methods recently proposed for estimating the soil hydraulic properties by numerical inversion of the Richards' equation are discussed. The first method involves the use of tension disc permeameter data, while the second method uses data collected with modified cone penetrometer. The third method involves the use of a multiple-step field extraction device. Experimental data for each of the

Molly M. Gribb; Jan W. Hopmans

57

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

58

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

59

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

NASA Astrophysics Data System (ADS)

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

Wang, Tiejun

2014-11-01

60

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

NASA Astrophysics Data System (ADS)

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

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

2009-12-01

61

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

62

Selected soil physical and hydraulic properties for different crop successions under no tillage  

NASA Astrophysics Data System (ADS)

No tillage is now widely widespread in Argentina in response to several circumstances, including limited runoff and a drop in soil erosion. Crop residues left on the soil surface help both natural rainfall and irrigation water infiltrate and also limits evaporation, conserving water for plant growth. This notwithstanding, wide differences in runoff rates between crop succession have been observed under no tillage. The aim of this work was to assess the effect of the main crop successions of Entre Ríos province, Argentina on selected soil physic and hydraulic properties. Results obtained on no-till plots were compared with those recorded on a 10-years old grassland plot and on a conventionally tilled plot left bare, both of them taken as references. The study soil was classified as an Aquic Argiudoll. Treatments were: maize and soybean, both cropped as monoculture, succession wheat/soybean or wheat/maize, grassland and conventionally tilled soil left bare. Soil runoff was recorded on experimental plots 100 m2 in surface. Saturated hydraulic conductivity (Khc) and sorptivity were measured in field conditions using a disc permeameter. Bulk density (Bd), saturated hydraulic conductivity (Kh) total porosity (TP) and pore size distributions were determined on undisturbed cores sampled at the 0-4 and 4-8 cm depth with five replications. Maximum water losses were recorded in bare soils conventionally tilled. Under maize and soybean monocultures water losses were six time higher than under grassland. Water losses under successions wheat/soybean-maize were lower than under monoculture but not significantly different. Field saturated hydraulic conductivity (Khc) was highest under grassland and the remaining treatments don't showed significant differences. Differences in sorptivity between plots were not significantly different. A significant relationship was found between saturated hydraulic conductivity measured in field conditions (Khc) and determined in soil cores (Kh) and on average the later was 2.5 times higher than the former. Soil pore space with diameters >50 m was higher under grassland at both sampling depths and showed no significant differences between other treatments. Saturated hydraulic conductivity (Khc), TP and Bd showed a significant relationship at the 0-4 cm depth. Runoff variance was explained by TP and partial porosity

Sasal, M. C.; Castiglioni, M.; Paz-Ferreiro, J.; Wilson, M. G.; Oszust, J.

2009-04-01

63

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

64

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

NASA Astrophysics Data System (ADS)

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

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

2004-05-01

65

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

66

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

NASA Astrophysics Data System (ADS)

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

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

2005-12-01

67

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

68

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

69

Vadose zone monitoring strategies to control water flux dynamics and changes in soil hydraulic properties.  

NASA Astrophysics Data System (ADS)

For monitoring the vadose zone, different strategies can be chosen, depending on the objectives and scale of observation. The effects of non-conventional water use on the vadose zone might produce impacts in porous media which could lead to changes in soil hydraulic properties, among others. Controlling these possible effects requires an accurate monitoring strategy that controls the volumetric water content, ?, and soil pressure, h, along the studied profile. According to the available literature, different monitoring systems have been carried out independently, however less attention has received comparative studies between different techniques. An experimental plot of 9x5 m2 was set with automatic and non-automatic sensors to control ? and h up to 1.5m depth. The non-automatic system consisted of ten Jet Fill tensiometers at 30, 45, 60, 90 and 120 cm (Soil Moisture®) and a polycarbonate access tube of 44 mm (i.d) for soil moisture measurements with a TRIME FM TDR portable probe (IMKO®). Vertical installation was carefully performed; measurements with this system were manual, twice a week for ? and three times per week for h. The automatic system composed of five 5TE sensors (Decagon Devices®) installed at 20, 40, 60, 90 and 120 cm for ? measurements and one MPS1 sensor (Decagon Devices®) at 60 cm depth for h. Installation took place laterally in a 40-50 cm length hole bored in a side of a trench that was excavated. All automatic sensors hourly recorded and stored in a data-logger. Boundary conditions were controlled with a volume-meter and with a meteorological station. ET was modelled with Penman-Monteith equation. Soil characterization include bulk density, gravimetric water content, grain size distribution, saturated hydraulic conductivity and soil water retention curves determined following laboratory standards. Soil mineralogy was determined by X-Ray difractometry. Unsaturated soil hydraulic parameters were model-fitted through SWRC-fit code and ROSETTA based on soil textural fractions. Simulation of water flow using automatic and non-automatic date was carried out by HYDRUS-1D independently. A good agreement from collected automatic and non-automatic data and modelled results can be recognized. General trend was captured, except for the outlier values as expected. Slightly differences were found between hydraulic properties obtained from laboratory determinations, and from inverse modelling from the two approaches. Differences up to 14% of flux through the lower boundary were detected between the two strategies According to results, automatic sensors have more resolution and then they're more appropriated to detect subtle changes of soil hydraulic properties. Nevertheless, if the aim of the research is to control the general trend of water dynamics, no significant differences were observed between the two systems.

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

2013-04-01

70

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

71

Using remotely-sensed estimates of soil moisture to infer soil texture and hydraulic properties across a semi-arid watershed  

Microsoft Academic Search

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

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

2007-01-01

72

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

73

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

E-print Network

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

Paris-Sud XI, Université de

74

Physical soil properties and slope treatments effects on hydraulic excavator productivity for forest road construction.  

PubMed

Effects of moisture, porosity and soil bulk density properties, grubbing time and terrain side slopes on pc 220 komatsu hydraulic excavator productivity were investigated in Miana forests road construction project which located in the northern forest of Iran. Soil moisture and porosity determined by samples were taken from undisturbed soil. The elements of daily works were measured with a digital stop watch and video camera in 14 observations (days). The road length and cross section profiles after each 20 m were selected to estimate earthworks volume. Results showed that the mean production rates for the pc 220 komatsu excavators were 60.13 m3 h(-1) and earthwork 14.76 m h(-1) when the mean depth of excavation or cutting was 4.27 m3 m(-1), respectively. There was no significant effects (p = 0.5288) from the slope classes' treatments on productivity, whereas grubbing time, soil moisture, bulk density and porosity had significantly affected on excavator earthworks volume (p < 0.0001). Clear difference was showed between the earthwork length by slope classes (p = 0.0060). Grubbing time (p = 0.2180), soil moisture (p = 0.1622), bulk density (p = 0.2490) and porosity (p = 0.2159) had no significant effect on the excavator earthworks length. PMID:18817241

Parsakho, Aidin; Hosseini, Seyed Ataollah; Jalilvand, Hamid; Lotfalian, Majid

2008-06-01

75

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

E-print Network

properties of peat soils 23 Hydrology and Earth System Sciences, 7(1), 23­32 (2003) © EGU An easily Kai Schwaerzel1 and Heiko P. Bohl2 1 Institute of Ecology, Department of Soil Sciences and Soil installable groundwater lysimeter to determine water balance components and hydraulic properties of peat soils

Boyer, Edmond

76

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

Microsoft Academic Search

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

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

1977-01-01

77

Unsaturated hydraulic conductivity function based on a soil fragmentation process  

E-print Network

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

Tartakovsky, Daniel M.

78

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

Microsoft Academic Search

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

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

2009-01-01

79

Residual effects of fallows on selected soil hydraulic properties in a kaolinitic soil subjected to conventional tillage (CT) and no tillage (NT)  

Microsoft Academic Search

Improved fallows have been used to reduce time required for soil fertility regeneration after cropping in low input agricultural\\u000a systems. In semi-arid areas of Southern Africa, Acacia angustissima and Sesbania sesban are among some of the more widely used improved fallow species. However the residual effects of improved fallows on soil\\u000a hydraulic properties during the cropping phase is not known.

G. Nyamadzawo; P. Nyamugafata; R. Chikowo; K. E. Giller

2008-01-01

80

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

Microsoft Academic Search

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

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

2007-01-01

81

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

Microsoft Academic Search

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

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

2008-01-01

82

UNSODA UNSATURATED SOIL HYDRAULIC DATABASE USER'S MANUAL VERSION 1.0  

EPA Science Inventory

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

83

Near-Surface Soil Moisture Assimilation to Quantify Effective Soil Hydraulic Properties Using Genetic Algorithm: A Field Scale Numerical and Validation Study  

NASA Astrophysics Data System (ADS)

Most large-scale soil-vegetation-atmosphere-transfer (SVAT) models rely on the use of soil hydraulic functions to describe the behavior of soil moisture in the unsaturated zone. The question of whether insitu or remotely sensed near-surface soil moisture temporal data is capable of quantifying the effective soil hydraulic properties is yet to be answered. In this paper, we present a near-surface soil moisture assimilation technique that can be possibly used to estimate the effective soil hydraulic parameters of the root zone. The procedure is based on inverse modeling using genetic algorithm to invert the soil moisture movement equation. Two major case studies were conducted: case (1) a field scale numerical study, and case (2) a field scale validation study. Case 1 is important for this kind of analysis because it can serve as a benchmark for further analysis. Under an error-free scenario, the only sources of uncertainties are the inverse procedure itself and parameter correlations and sensitivities. We found that the identifiability of parameters increases as we approach the outer ranges of the soil textural class. We also found that parameter identifiability is higher when the soil is predominantly drying than when being dominated by upward flux from a shallow water table. When the contribution of the upward flux exceeds 50 percent of the seasonal evapotranspiration (ET), the near-surface soil moisture assimilation fails. For Case 2, we used in situ datasets from SGP97 and SMEX02 hydrology campaigns. In real-world conditions, uncertainties in measurement, model, boundary conditions, etc. could influence the outcomes of the experiments. We examined some of these sources of uncertainties in our analyses and observed how the solutions behaved. Generally, the uncertainties pertaining to initial and bottom boundary conditions impact significantly the available mass of water in the soil profile and tend to underestimate soil moisture in the subsurface layers even if the simulated near-surface soil moisture fitted well with the observed data. Likewise, if they are not well represented, root length and density impacted the simulated sub-surface soil moisture. Our results demonstrate that using the right combination of conditions to define the effective modeling domain is important in implementing near-surface soil moisture assimilation for real-world conditions.

Ines, A. V.; Mohanty, B. P.

2005-12-01

84

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

85

COMPARACIÓN DE METODOLOGÍAS DE CÁLCULO DE PROPIEDADES HIDRÁULICAS DE UN SUELO A PARTIR DE DATOS MEDIDOS CON INFILTRÓMETRO DE DISCO Comparison of calculation methodologies of hydraulic properties of a soil from data measured with a disc infiltrometer  

Microsoft Academic Search

A B S T R A C T Tension disc infiltrometers are being increasingly used for determining in situ saturated and near-saturated soil hydraulic properties. The objective of this paper was to compare two calculation methodologies for different soil hydraulic properties starting from data measured with a disc tension infiltrometer. The experiment was carried out on packed soil in samples

Antonio M. Aoki; Roberto Sereno

86

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

87

May 10, 2013 Determining Soil Hydraulic Conductivity  

E-print Network

May 10, 2013 Determining Soil Hydraulic Conductivity from Cosmic-ray Neutron Data Adam M Current methods used to quantify hydraulic conductivity require either lab testing of soil samples trends of the COSMOS soil moisture signal, it may be possible to estimate area averaged soil hydraulic

Fay, Noah

88

Comparison of Methods for Determining Soil Hydraulic Characteristics  

E-print Network

An adequate description of soil moisture movement is necessary for solution of agriculturally oriented problems such as irrigation, drainage and runoff control. Three approaches for determining the hydraulic properties of soil are in situ...

Howell, T. A.; McFarland, M. J.; Reddell, D. L.; Brown, K. W.; Newton, R. J.; Humphreys, K. B.

89

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

90

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

91

Physically-based model of soil hydraulic properties accounting for variable contact angle and its effect on hysteresis  

NASA Astrophysics Data System (ADS)

The description of soil water movement in the unsaturated zone requires the knowledge of the soil hydraulic properties, i.e. the water retention and the hydraulic conductivity function. A great amount of parameterizations for this can be found in the literature, the majority of which represent the complex pore space of soils as a bundle of cylindrical capillary tubes of various sizes. The assumption of zero contact angles between water and surface of the grains is also made. However, these assumptions limit the predictive capabilities of these models, leading often to errors in the prediction of water dynamics in soils. We present a pore-scale analysis for equilibrium liquid configuration in angular pores taking pore-scale hysteresis and the effect of contact angle into account. Furthermore, we propose a derivation of the hydraulic conductivity function, again as a function of the contact angle. An additional parameter was added to the conductivity function in order take into account effects which are not included in the analysis. Finally, we upscale our model from the pore to the sample scale by assuming a gamma statistical distribution of the pore sizes. Closed-form expressions are derived for both water retention and conductivity functions. The new model was tested against experimental data from multistep inflow/outflow (MSI/MSO) experiments for a sandy material. They were conducted using ethanol and water as the wetting liquid. Ethanol was assumed to form a zero contact angle with the soil grains. By keeping constant the parameters fitted from the ethanol MSO experiment we could predict the ethanol MSI dynamics based on our theory. Furthermore, by keeping constant the pore size distribution parameters from the ethanol experiments we could also predict very well the water dynamics for the MSO experiment. Lastly, we could predict the imbibition dynamics for the water MSI experiment by introducing a finite value of the contact angle. Most importantly, the predictions for both ethanol and water MSI/MSO dynamics were made by assuming a unique pore-size distribution.

Diamantopoulos, Efstathios; Durner, Wolfgang

2013-09-01

92

Using an inverse method to estimate the hydraulic properties of crusted soils from tension-disc infiltrometer data  

Microsoft Academic Search

An inverse procedure was used to estimate the soil hydraulic characteristics of a two-layered soil system—soil surface crust and subsoil—from data obtained during a tension-disc infiltration experiment. The inverse procedure combined the Levenberg–Marquardt nonlinear parameter optimization method with a numerical solution of the axisymmetric variably-saturated flow equation. The objective function was defined in terms of the cumulative infiltration curve and

Ji??? Šim?nek; Rafael Angulo-Jaramillo; Marcel G. Schaap; Jean-Pierre Vandervaere; Martinus Th. van Genuchten

1998-01-01

93

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

NASA Astrophysics Data System (ADS)

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

Assouline, Shmuel

2013-04-01

94

Impact of Fly Ash Amendment and Incorporation Method on Hydraulic Properties of a Sandy Soil  

Microsoft Academic Search

Coal fly ash has physical and chemical characteristics that makeit useful as a soil amendment, one of the more important beingthe potential to permanently improve the soil water relations ofsandy, drought-prone soils. We axemined changes in theinfiltration rate and water holding capacity of a sandy soilafter application of high rates (up to 950 Mg ha-1) of aClass F fly ash.

W. J. Gangloff; M. Ghodrati; J. T. Sims; B. L. Vasilas

2000-01-01

95

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

SciTech Connect

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

Ebel, Brian A.; Nimmo, John R.

2009-12-29

96

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

97

Time-Dependent Soil Hydraulic Conductivity in Salt-Affected Soils  

NASA Astrophysics Data System (ADS)

Mixed salts such as sodium-calcium salts interact with the soil matrix. The physico chemical interactions between the soil solution and the soil matrix (SS-SM), particularly in the presence of smectite minerals (e.g., montmorillonite), may change the soil pore-size distribution; the latter could affect the soil hydraulic properties, i.e., the soil hydraulic conductivity and soil water retention. Since the magnitude of the SS-SM interactions depend on time-dependent flow-controlled attributes, i.e., soil solution concentration and composition and water content, the resultant hydraulic properties are also time-dependent. The present talk focuses on the effect of mixed-ion solutions on soil hydraulic properties relevant to water flow and solute transport. Experimental evidence on, and an approach for modeling of the effect of soil solution concentration and composition on the local- (Darcy) scale soil hydraulic properties are presented and discussed. Long-term effect of the soil solution concentration and composition on the soil hydraulic properties, and, concurrently, on water flow and solute transport are presented through simulations of field-scale flow and transport.

Russo, D.

2012-04-01

98

Estimating Soil Water Retention and Unsaturated Soil Hydraulic Conductivity of Aggregated Soils Using the Additivity Model  

NASA Astrophysics Data System (ADS)

Soil-water potential and hydraulic conductivity relationships with soil water content are needed for many plant and soil-water studies. Conventional soil pore space model lying in the base of "one pore region - one continuum", described by pair of water retention and unsaturated soil hydraulic functions, often oversimplifies representation of variably saturated porous media as a homogeneous textural pore space. Soil structure has a major effect on soils ability to retain and to conduct water. This is especially right for aggregated soils in which pore space consists of interconnected intra- and inter-aggregate pores with distinct hydraulic properties. When a proportion of the inter-aggregate pore space is significant, in many cases the conventional description of water flow provides results that don't much an experimental data. In case of developed "aggregated soil" based on the concept "two pore regions - two continuums" soil pore space is described by two pair of both unsaturated soil hydraulic functions. A special model to estimate these functions is developed based on input data of bulk and aggregate density, structural and textural component distributions. This model was tested with experimental data measured of water retention and hydraulic conductivity of soil cores consisting of aggregates with sizes within narrow ranges. Cores were fabricated from separated individual aggregate fractions of Halpic Chernozem, Podzoluvisol, Halpic Kastanozem soils and artificially prepared aggregates. The obtained results demonstrate the sensitivity of the "additivity" model to estimate both unsaturated soil hydraulic functions for each pore regions. Keywords: aggregated soil, soil structure, soil water retention, additivity model

Zeiliger, A.; Ermolaeva, O.

2009-04-01

99

Comparing time-lapse GPR data collected under natural and forced infiltration conditions to estimate unsaturated soil hydraulic properties  

NASA Astrophysics Data System (ADS)

Geophysical methods can provide valuable information on vadose zone hydrological properties and reduce uncertainties in the estimation of the van Genuchten-Mualem (VGM) parameters, which provide a comprehensive description of the soil water retention characteristics. In particular, time lapse crosshole GPR measurements allow for the monitoring of water content changes in the subsurface during infiltration, which can be used to effectively estimate the pertinent hydraulic parameters when combined with a process-based model. Infiltration can be monitored under natural or forced loading conditions. Under natural loading, a number of studies have found the estimation of the VGM parameters to be difficult because changes in moisture content over time can be quite small. Specifically, multiple measurements over time have been found to provide only limited additional constraints on the estimated hydraulic parameters. A forced infiltration test can help to overcome this issue by producing large variations in subsurface water content. However, this type of experiment may disturb the original medium and hence may result in errors related to the forced, artificial conditions. Here, our goal is to compare the results of inverting time-lapse GPR data collected under natural loading conditions with those collected during a forced infiltration experiment. Recent research has shown that stochastic inverse methods can be an effective means of accounting for the inherent non-linearity and non-uniqueness in coupled hydrogeophysical parameter estimation problems. Therefore, we perform our inversion within a Bayesian framework and use a Markov chain Monte Carlo (McMC) strategy to estimate the posterior distributions of model parameters. With this methodology, parameter uncertainties can be obtained and parameter distributions can be compared between the two experiment types. Using a synthetic example, we first examine a five-layer case and invert for the VGM parameters for each layer. We then apply our inversion approach to data from a field experiment conducted near Arrenaes in eastern Denmark. Our initial results, which are largely based on evidence from the synthetic study, indicate that the saturated hydraulic conductivity tends to be better resolved under forced infiltration than under natural loading conditions.

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

2012-04-01

100

Influence of relative surface age on hydraulic properties and infiltration on soils associated with desert pavements  

E-print Network

dyed water and a tension disc infiltrometer, set to saturation. Following the tests the soil for plant growth in desert regions (Smith et al., 1997). Water is also a major transporter of nutrients and overland flow strongly affect the redistribution of sediment, plant litter, and seeds, vertically

Ahmad, Sajjad

101

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

E-print Network

in this work including: ambient light, MLT scanner positioning in relation to the soil surface, and post-processing procedures for the resulting data. MLT scans capture the profile surface along with areas of missing data, termed surface scan gaps (SSGs), which...

Eck, Dennis V.

2014-05-31

102

Soil Hydraulic Characteristics of a Small Southwest Oregon Watershed Following  

E-print Network

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

Standiford, Richard B.

103

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

104

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

105

Efficient hydraulic properties of root systems  

NASA Astrophysics Data System (ADS)

Understanding the mechanisms of ecosystem root water uptake (RWU) is paramount for parameterizing hydrological models. With the increase in computational power it is possible to calculate RWU explicitly up to the single plant scale using physical models. However, application of these models for increasing our understanding of ecosystem root water uptake is hindered by the deficit in knowledge about the detailed hydraulic parameter distribution within root systems. However, those physical models may help us to identify efficient parameterizations and to describe the influence of these hydraulic parameters on RWU profiles. In this research, we investigated the combined influence of root hydraulic parameters and different root topologies on shaping efficient root water uptake. First, we use a conceptual model of simple branching structures to understand the influence of branching location and transitions in root hydraulic properties on the RWU patterns in typical sub root structures. Second, we apply a physical model called "aRoot" to test our conclusions on complex root system architectures of single plants. aRoot calculates the distribution of xylem potential within arbitrary root geometries to satisfy a given water demand depending on the available water in the soil. Redistribution of water within the bulk soil is calculated using the Richards equation. We analyzed results using a measure of uptake efficiency, which describes the effort necessary for transpiration. Simulations with the conceptual model showed that total transpiration in sub root structures is independent of root hydraulic properties over a wide range of hydraulic parameters. On the other hand efficiency of root water uptake depends crucially on distribution hydraulic parameters in line with root topology. At the same time, these parameters shape strongly the distribution of RWU along the roots, and its evolution in time, thus leading to variable individual root water uptake profiles. Calculating RWU of three dimensional root architectures unveiled that the same effects can be observed at the single plant scale. Total transpiration is almost independent of root hydraulic properties. On the other hand, the arrangement of hydraulic properties significantly influences RWU efficiency. Furthermore the vertical root water uptake profiles are governed by the different root properties. They result from two combined re-distribution patterns over time: One within a rooting branch similar to the results mentioned above, and a second one between the different rooting branches within the root system. This leads to complex vertical uptake profiles, which cannot be predicted from a combination of root abundance and soil moisture, and depend strongly on the individual morphology.

Bechmann, Marcel; Schneider, Christoph; Carminati, Andrea; Hildebrandt, Anke

2013-04-01

106

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.

107

Xylem Hydraulics and the SoilPlantAtmosphere Continuum: Opportunities and Unresolved Issues  

E-print Network

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

Stiller, Volker

108

Effective hydraulic parameters for steady state vertical flow in heterogeneous soils  

E-print Network

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

Mohanty, Binayak P.

109

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

E-print Network

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

Paris-Sud XI, Université de

110

Spatial structure of hydraulic properties from canopy to interspace in the Mojave Desert  

Microsoft Academic Search

Desert piedmonts are a mosaic of interspersed vegetation and bare soil, previously considered to be a binary system of canopy and interspace microsites. The spatial structure of soils and hydraulic properties in these microsites affects our ability to upscale or downscale observed processes. We determined variability and spatial correlation of hydraulic properties using high-resolution measurements of unsaturated hydraulic conductivity [K(?)

Todd G. Caldwell; Michael H. Young; Jianting Zhu; Eric V. McDonald

2008-01-01

111

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

112

A laboratory method to determine the hydraulic conductivity of mountain forest soils using undisturbed soil samples  

NASA Astrophysics Data System (ADS)

Determination of infiltration properties of soils under laboratory conditions necessitates the collection of soil samples in a way that maintains their natural physical properties. Mountain forest soils, containing rock fragments, root systems and a significant amount of organic matter, make it extremely difficult to test their hydraulic conductivity using both laboratory and field methods. A widely used technique of sampling by driving a cylinder into the ground in this type of soils causes damage to their structure resulting from the displacement of root systems and rock fragments as well as reduction of soil porosity. Thus, subsequent results contain an error that is difficult to estimate. The aim of the present research was: (1) to develop a laboratory method for testing the hydraulic conductivity of mountain forest soils, and in particular a method of collection of undisturbed soil samples, (2) to determine the influence of the applied method of collecting samples on the thickening of their peripheral layer and on elimination of increased infiltration at the boundary between the soil medium and the cylinder, (3) to determine the extent of the impact of the irregular shape of a sample on its hydraulic conductivity and (4) to develop an empirical method for determining the actual values of hydraulic conductivity, taking into account the error associated with the flow of water through samples with different shapes. The method of soil sampling consists in gradual formation of a cylindrical soil monolith and filling the free space between the monolith and the tri-cylindrical container with low-pressure assembly foam. This method ensures preservation of the natural physical properties of the examined samples and elimination of errors during the measurement of the hydraulic conductivity, caused by increased infiltration at the boundary between the soil medium and the cylinder. It was shown that the mean error of hydraulic conductivity determination, related to the irregular shape of samples, amounts to 11.57%. The error may be eliminated by the application of conversion coefficients.

Ilek, Anna; Kucza, Jaros?aw

2014-11-01

113

SOIL HYDRAULIC CONDUCTIVITY AND RETENTION CURVES FROM TENSION INFILTROMETER AND LABORATORY DATA  

Microsoft Academic Search

Long term tillage effects may be characterized on the basis of changes in soil surface hydraulic properties. These properties directly influence infiltration as well as the movement of soil water to the surface during drying. We measured surface soil hydraulic properties on no-till (NT) and conventional (stubble mulch) tillage (CT) plots, each of which was farmed with either a wheat-sorghum-fallow

S. R. Evett; F. H. Peters; O. R. Jones; P. W. Unger

114

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...

115

Effective Hydraulic Conductivity of Unsaturated Isotropic Soils with Multidimensional Heterogeneity  

SciTech Connect

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

Zhang, Z. F.

2010-05-01

116

Irrigation with treated wastewater under two different irrigation methods: Effects on hydraulic conductivity of a clay soil  

Microsoft Academic Search

Use of treated wastewater (TWW) for irrigation of semiarid and arid soils may lead to degradation of soil hydraulic properties, the magnitude of which may depend on the type of the irrigation system. Most studies evaluated the impact of irrigation with TWW on soil hydraulic conductivity (HC) using repacked samples, which do not necessarily represent soil field conditions. Our objectives

A. K. Bhardwaj; D. Goldstein; A. Azenkot; G. J. Levy

2007-01-01

117

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

Microsoft Academic Search

Upscaled soil hydraulic properties are needed for many large-scale hydrologic applications such as regional and global climate studies and investigations of land-atmosphere interactions. Many larger scale sub- surface flow and contaminant transport studies also require upscaled hydraulic property estimates. The objectives of this study were to de- velop a methodology for upscaling hydraulic property functions using a p-norm approach, to

Jianting Zhu; Michael H. Young; Martinus Th. van Genuchten

2007-01-01

118

Hydraulic functions for swelling soils: pore scale considerations  

NASA Astrophysics Data System (ADS)

Changes in volume and pore space induced by the shrink-swell behavior of clay minerals present a challenge to predictive modeling of hydraulic properties of clayey soils. Despite well-developed theory for crystalline and osmotic swelling of clay minerals at the scale of individual clay lamellae, their translation to prediction of hydraulic properties of swelling soils is limited. In this study we propose a framework that combines physico-chemical processes with pore scale geometrical, hydrostatic, and hydrodynamic considerations toward prediction of constitutive hydraulic relationships for swelling porous media. Variations in pore space are modeled by considering the soil clay fabric as an assembly of colloidal-size tactoids with lamellar structure. The arrangement of clay tactoids and the spacing between individual lamellae are functions of primarily clay hydration state quantifiable via the disjoining pressure that is dominated by a large electrostatic repulsive component. Solution chemistry and clay type are also considered. Silt and sand textural constituents are represented as rigid spheres interspaced by clay fabric in two basic configurations of 'expansive' and 'reductive' unit cells. Bulk soil properties such as clay content, porosity and surface area serve as constraints for the pore-space geometry. Liquid saturation within the idealized pore space is calculated as a function of chemical potential considering volume changes due to clay shrink-swell behavior. Closed-form expressions for prediction of saturated hydraulic conductivity are derived from calculations of average flow velocities in ducts and between parallel plates, and invoking proportionality between water flux density and unit hydraulic gradient. Preliminary model calculations compare favorably with published data, and show great potential for upscaling considerations.

Tuller, Markus; Or, Dani

2003-03-01

119

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

E-print Network

TDR System for Hydraulic Characterization of Unsaturated Soils in the Centrifuge John S. McCartney1@mail.utexas.edu Abstract A centrifuge permeameter has been developed to provide expedited determination of the hydraulic bucket. The hydraulic properties of a soil specimen are measured using the centrifuge permeameter

Zornberg, Jorge G.

120

Evaluating models for predicting hydraulic characteristics of layered soils  

NASA Astrophysics Data System (ADS)

Soil water characteristic curve (SWCC) and unsaturated hydraulic conductivity (K-coefficient) are critical hydraulic properties governing soil water activity on layered soils. Sustainable soil water conservation would not be possible without accurate knowledge of these hydraulic properties. Infield rainwater harvesting (IRWH) is one conservation technique adopted to improve the soil water regime of a number of clay soils found in the semi arid areas of Free State province of South Africa. Given that SWCC is much easier to measure, most soil water studies rely on SWCC information to predict in-situ K-coefficients. This work validated this practice on the Tukulu, Sepane and Swartland layered soil profiles. The measured SWCC was first described using Brooks and Corey (1964), van Genuchten (1980) and Kasugi (1996) parametric models. The conductivity functions of these models were then required to fit in-situ based K-coefficients derived from instantaneous profile method (IPM). The same K-coefficient was also fitted by HYDRUS 1-D using optimised SWCC parameters. Although all parametric models fitted the measured SWCC fairly well their corresponding conductivity functions could not do the same when fitting the in-situ based K-coefficients. Overestimates of more than 2 orders of magnitude especially at low soil water content (SWC) were observed. This phenomenon was pronounced among the upper horizons that overlaid a clayey horizon. However, optimized ? and n parameters using HYDRUS 1-D showed remarkable agreement between fitted and in-situ K-coefficient with root sum of squares error (RMSE) recording values not exceeding unity. During this exercise the Brooks and Corey was replaced by modified van Genuchten model (Vogel and Cislerova, 1988) since it failed to produce unique inverse solutions. The models performance appeared to be soil specific with van Genuchten-Mualem (1980) performing fairly well on the Orthic and neucutanic horizons while its modified form fitted very well the prismatic and pedo-cutanic horizons. The lognormal distribution model of Kasugi (1996) showed an extraordinary good fit among the Swartland profile horizons especially the saprolite rock layer. It was therefore concluded that in-situ KL-coefficient estimates from SWCC parameters could be acceptable if only rough estimates were required. Optimization of parameters for in-situ conditions especially for HYDRUS 1-D carried much prospects in characterising the hydraulic properties of most of the layered soils earmarked for IRWH in the province.

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

2012-01-01

121

Dynamics of hydraulic properties due to biological clogging  

NASA Astrophysics Data System (ADS)

Classic treatment of soil-water flow is described by the unsaturated version of Darcy's law and Richards' equation, assuming time invariant hydraulic properties, e.g. the saturated hydraulic conductivity, Ks, and van Genuchten-Mualem's ? and n. However, when bacteria is present the soil is quite far from being time invariant and biological activity constantly alters the pore-scale structure, leading to macro-scale alteration of the hydraulic properties. This may be of high relevance to processes such as subsurface bioremediation, soil aquifer treatment, wastewater irrigation, and more. In this work we explore the dynamic alteration of soil hydraulic properties by a combination of column experiments and pore-network modeling. We experimentally demonstrate how biological activity clogs an unsaturated soil column and reduces its hydraulic conductivity, while a similar column where biological activity is limited does not clog. Further, we demonstrate that the clogging is preferential to the nutrient input. Next, we develop a pore-network model that uses triangular shape channels. This allows a dual occupancy (water-air) of each channel and high connectivity. The model solves the flow of water, nutrient transport, and biological dynamics. It includes biofilm growth and decay, attachment and detachment, and nutrient exchange between the water and biofilm phases. We perform a sensitivity analysis of the model and qualitatively show through the loss of connectivity how the clogging that was observed in our experiment can be explained.

Rosenzweig, R.; Shavit, U.; Furman, A.

2012-04-01

122

Mucilage: The hydraulic bridge between roots and soil  

NASA Astrophysics Data System (ADS)

As plant roots take up water and the soil dries, water depletion is expected to occur in the soil near the roots, the so called rhizosphere. Ultimately, as the soil hydraulic conductivity drops and the soil cannot sustain the transpiration demand, roots shrink and lose contact to the soil. Both, water depletion in the rhizosphere and formation of air-filled gaps at the root-soil interface potentially limit the availability of water to plants. How can plants overcome these potential hydraulic barriers at the root-soil interface? One strategy consists in the exudation of mucilage from the root tips. Mucilage is a polymeric gel that is capable of holding large volumes of water. When exuded into the soil, mucilage remains in the vicinity of roots thanks to its relatively high viscosity and reduced surface tension. As mucilage is mainly made of water, its slow penetration into the soil results in higher water content and hydraulic conductivity of the rhizosphere compared to the adjacent bulk soil. Recent measurements with a root pressure probe technique demonstrated that mucilage exudation facilitates the water flow in dry soils. Additionally, mucilage increases the adhesion of soil particles to the roots, reducing the formation of gaps at the root-soil interface. Based on these observations, it is very tempting to conclude that mucilage acts as an optimal hydraulic bridge across the root-soil interface. However, as mucilage dries and ages, it turns hydrophobic. Consequently, the rhizosphere becomes water repellent and its rewetting time increases. Our former experiments showed that after irrigation subsequent to a drying cycle, the rhizosphere of lupines remained markedly dry for 2 days. Recently, we demonstrated that the rhizosphere water repellency is concomitant with a decrease in local water uptake of 4-8 times. We conclude that after drying and rewetting, the rhzisophere temporarily limits root water uptake. In summary, the hydraulic properties of the root-soil interface changes over time and along the root system. Young, well hydrated mucilage optimally connects the roots to the soil and facilitates the uptake of water from relatively dry soils. However, as mucilage ages and dries, it reduces the rhizosphere wettability and the water flow to the roots. Such a dual behavior of the rhizosphere, rather than a contradiction, seems a plant strategy to adapt to the typically heterogeneous distribution of water in soils. For instance, in a soil profile with water stored in the sub soil, mucilage would facilitate the water uptake of young, deep root segments and it would avoid water loss from the root segments into the dry top soil. These studies show that the root-soil interactions in the rhizosphere play a crucial role in regulating root water uptake. We believe that s better understanding and management of such interactions can bring a more efficient and sustainable use of water resources.

Carminati, Andrea; Zarabanadkouki, Mohsen; Kroener, Eva; Ahmed, Mutez A. A.

2014-05-01

123

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

124

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

E-print Network

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

Stiller, Volker

125

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

126

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

NASA Astrophysics Data System (ADS)

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.

Šim?nek, Jirka; Nimmo, John R.

2005-04-01

127

Combined effect of interblock and interaggregate capillary cracks on the hydraulic conductivity of swelling clay soils  

NASA Astrophysics Data System (ADS)

The cracks in swelling clay soils at sufficiently high water content can be presented as the superposition of interblock- and interaggregate-capillary-crack networks. The objective of this work is the generalization of an earlier proposed model describing the hydraulic conductivity of a soil matrix with only interaggregate capillary cracks. The generalized model describes the hydraulic conductivity of a soil with capillary cracks of both types. For the case of vertical hydraulic conductivity the generalization is based on the available results relative to the geometrical and hydraulic properties of capillary crack networks. The contribution of interblock capillary cracks to the hydraulic conductivity of a soil at a given pressure head changes with depth even for a given matrix structure, contrary to the contributions of interaggregate capillary cracks and soil matrix. For numerical estimates and validation of the model we use literature data on the variation of water content in different soil layers, evaporation, subsidence, and crack volume during a drying period in the course of a laboratory lysimeter experiment. The numerical estimates indicate the essential and even prevailing contribution of capillary cracks of both types to hydraulic conductivity at sufficiently small pressure heads and their negligible contribution to the water retention of clay soil. The validation is based on a comparison between two independent estimates of the summary hydraulic conductivity of the soil matrix and interaggregate capillary cracks. One of these estimates is found as a difference between the total hydraulic conductivity of the soil and the hydraulic conductivity of the interblock-capillary-crack network. Another estimate is found by the model describing the hydraulic conductivity of a soil matrix with only interaggregate capillary cracks. The results of the comparison validate the feasibility of the model showing that it is in agreement with the available data of the lysimeter experiment.

Chertkov, V. Y.; Ravina, I.

2002-08-01

128

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

E-print Network

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

Paris-Sud XI, Université de

129

www.VadoseZoneJournal.org Estimation of Soil Hydraulic  

E-print Network

www.VadoseZoneJournal.org Estimation of Soil Hydraulic Parameters in the Field by Integrated approach was used to remotely infer the unsat- urated soil hydraulic parameters from time-lapse ground media together with global reflection and transmission functions to account for the antenna and its

Hubbard, Susan

130

Derivation of Soil Moisture Retention Characteristics from Saturated Hydraulic Conductivity  

E-print Network

1 Derivation of Soil Moisture Retention Characteristics from Saturated Hydraulic Conductivity C. P systems require knowledge of the relationships between soil moisture content (), soil water pressure (h involved field and laboratory determination of soil moisture characteristics along the Hindon river in its

Kumar, C.P.

131

Soil hydraulic parameters estimated from satellite information through data assimilation  

Microsoft Academic Search

Leaf area index (LAI) and actual evapotranspiration (ETa) from satellite observations were used to estimate simultaneously the soil hydraulic parameters of four soil layers down to 60 cm depth using the combined soil water atmosphere plant and genetic algorithm (SWAP–GA) model. This inverse model assimilates the remotely sensed LAI and\\/or ETa by searching for the most appropriate sets of soil

Sujittra Charoenhirunyingyos; Kiyoshi Honda; Daroonwan Kamthonkiat; Amor V. M. Ines

2011-01-01

132

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

133

HYDRAULIC REDISTRIBUTION OF SOIL WATER IN TWO OLD-GROWTH CONIFEROUS FORESTS: QUANTIFYING PATTERNS AND CONTROLS  

EPA Science Inventory

Although hydraulic redistribution of soil water (HR) by roots is a widespread phenomenon, the processes governing spatial and temporal patterns of HR are not well understood. We incorporated soil/plant biophysical properties into a simple model based on Darcy's law to predict sea...

134

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...

135

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...

136

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

E-print Network

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

137

The Effect of Entrapped Air on the Quasi-Saturated Soil Hydraulic Conductivity and Comparison with the Unsaturated Hydraulic Conductivity  

Microsoft Academic Search

loam or sandy loam soils. It is not clear how much air can be entrapped in aggregated soils. Entrapped air can greatly affect the hydraulic conductivity at or Various papers have reported the effect of entrapped near saturation. In this study, we measured the hydraulic conductivity and volume of entrapped air in a quasi-saturated soil. Two soils, a air on

A. Sakaguchi; T. Nishimura; M. Kato

2005-01-01

138

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

139

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

140

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

Microsoft Academic Search

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

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

2001-01-01

141

www.VadoseZoneJournal.org Es ma on of Soil Hydraulic  

E-print Network

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

Hubbard, Susan

142

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

SciTech Connect

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

Wolock, D.M.

1988-01-01

143

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

144

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

145

ORIGINAL PAPER Hydraulic properties and embolism in small-diameter  

E-print Network

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

Paris-Sud XI, Université de

146

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

147

Effective Hydraulic Conductivity of Partially Inundated Surfaces: Loamy Agricultural Soils  

NASA Astrophysics Data System (ADS)

Observed runoff coefficients decrease from small plots to the agricultural hillslope scale, even if a field does not show spatial trends of soil properties. Apart from the temporal effect of re-infiltration of rainfall excess after a rainfall peak, studies have focused on two other aspects of infiltration that are also relevant for steady state field experiments. First, a micro-scale distribution of infiltration capacities implies that final infiltration rates increase with rainfall intensity. Secondly, a systematic distribution of infiltration capacities from sealed micro-channel bottoms to unsealed micro-mounds implies that final infiltration rates increase with average water depth on a partially inundated surface. Although these phenomena have been known and experimentally studied for some time, soil erosion models still assume infiltration capacity to be independent of water depth/rainfall intensity. This may lead to important errors when the results of these models are upscaled from the plot scale (< 30 m) to the field scale (100-500 m). There is therefore a need to develop modelling concepts that explicitly account for the dependency of infiltration on rainfall intensity and water depth so that process-based erosion models may be built providing more realistic results at the field scale. This study seeks to contribute to the development of a dynamic infiltration model suitable for agricultural hillslopes. Experiments were conducted on maize fields in Belgium. Final infiltration rates were measured on small plots (0.68 m2) during rainfall simulation with stages of rainfall intensity between 8 and 130 mm h-1, during inflow applied at the upslope border of the plot (1.6E-6 to 2.5E-5 m3s-1) and during a combination of both. Combining pinmeter profiles with photos of the inundated surface allowed estimating hydraulic variables of the flow on the plot. Linear functions were developed from this data that estimate average water depth and the fraction of the surface that is inundated. Distributions of infiltration capacities were assumed to lie between a Kmax and a Kmin parameter and average hydraulic conductivities were calculated for the inundated and not inundated partition differently, allowing interaction. Final infiltration rates were estimated for an evaluation dataset with a Model Efficiency of 0.88. The estimates can alternatively be interpreted as effective hydraulic conductivities (Ke), dynamically dependent on inflow and rainfall intensity. The presented concept has the scope to account for a substantial part of the observed scale effects in runoff coefficients on arable land.

Langhans, C.; Govers, G.; Diels, J.

2010-12-01

148

Hydraulic conductivity estimation for soils with heterogeneous pore structure  

Microsoft Academic Search

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

Wolfgang Durner

1994-01-01

149

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

150

Description of the unsaturated soil hydraulic database UNSODA version 2.0  

NASA Astrophysics Data System (ADS)

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

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

2001-10-01

151

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

152

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

NASA Astrophysics Data System (ADS)

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

Schindler, Uwe; Mueller, Lothar

2013-04-01

153

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

PubMed Central

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

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

2014-01-01

154

Hydraulic redistribution of soil water by neotropical savanna trees.  

PubMed

The magnitude and direction of water transport by the roots of eight dominant Brazilian savanna (Cerrado) woody species were determined with a heat pulse system that allowed bidirectional measurements of sap flow. The patterns of sap flow observed during the dry season in species with dimorphic root systems were consistent with the occurrence of hydraulic redistribution of soil water, the movement of water from moist to drier regions of the soil profile via plant roots. In these species, shallow roots exhibited positive sap flow (from the soil into the plant) during the day and negative sap flow (from the plant into the soil) during the night. Sap flow in the taproots was positive throughout the 24-h period. Diel fluctuations in soil water potential, with maximum values occurring at night, provided evidence for partial rewetting of upper soil layers by water released from shallow roots. In other species, shallow roots exhibited negative sap flow during both the day and night, indicating that hydraulic redistribution was occurring continuously. A third sap flow pattern was observed at the end of the dry season after a heavy rainfall event when sap flow became negative in the taproot, and positive in the small roots, indicating movement of water from upper soil layers into shallow roots, and then into taproots and deeper soil layers. Experimental manipulations employed to evaluate the response of hydraulic redistribution to changes in plant and environmental conditions included watering the soil surface above shallow roots, decreasing transpiration by covering the plant and cutting roots where probes were inserted. Natural and manipulated patterns of sap flow in roots and stems were consistent with passive movement of water toward competing sinks in the soil and plant. Because dry shallow soil layers were often a stronger sink than the shoot, we suggest that the presence of a dimorphic root system in deciduous species may play a role in facilitating leaf expansion near the end of the dry season when the soil surrounding shallow lateral roots is still dry. PMID:12069916

Scholz, Fabian G; Bucci, Sandra J; Goldstein, Guillermo; Meinzer, Frederick C; Franco, Augusto C

2002-06-01

155

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

E-print Network

SOIL MOISTURE RETENTION CHARACTERISTICS AND HYDRAULIC CONDUCTIVITY FOR DIFFERENT AREAS IN INDIA systems require knowledge of the relationships between soil moisture content (), soil water pressure (h the approximate soil moisture retention curve at the places where only saturated hydraulic conductivity data

Kumar, C.P.

156

Estimating Soil Hydraulic Parameters of a Field Drainage Experiment Using Inverse Techniques  

SciTech Connect

The unsteady drainage-flux method is one of the commonly used methods to measure in situ unsaturated hydraulic properties in soils. However, the properties obtained by the method using instantaneous profile data analysis may not be the best estimation of actual values of hydraulic properties. We present an improved analysis of the data from drainage experiments using inverse modeling, which uses nonlinear regression methods to estimate hydraulic parameters. Parameter identifiability is evaluated through sensitivity and uniqueness analyses. We used the combination of the inverse modeling program, UCODE, with the flow simulator, STOMP, for inverse modeling. Applying the inverse method to a field drainage experiment in sandy soil shows that all the van Genuchten (1980) hydraulic parameters could be estimated uniquely when both water content (q) and pressure head (y) data were used. The best parameter estimates by inverse technique using both q and y data simulate the flow better than the parameter values obtained by the conventional instantaneous-profile analysis method. After the spatial and temporal sensitivities were analyzed, a more rational experimental design was recommended.

Zhang, Z. F.; Ward, Anderson L.; Gee, Glendon W.

2003-05-01

157

HYDRAULIC CONDUCTIVITY ESTIMATION IN PARTIALLY SATURATED SOILS USING THE ADJOINT METHOD  

E-print Network

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

Efendiev, Yalchin

158

In situ estimation of soil hydraulic functions using a multistep soil-water extraction technique  

Microsoft Academic Search

Abstract. Estimation of the retention and unsaturated,hydraulic conductivity functions is essential to effectively provide input for water flow and transport simulation,and prediction. A parameter,optimization,procedure,is shown,as a promising,tool to estimate inversely these hydraulic function parameters,from transient soil matric potential and cumulative,soil solution extraction measurements.,Sensitivity analyses from synthetic data generated,from forward,numerical,model,simulations showed,that optimum,tensiometer locations will depend,on soil type. Experiments,were carried out in

M. Inoue; J. Šimunek; J. W. Hopmans; V. Clausnitzer

1998-01-01

159

Hydraulic Functions for Swelling Soils: Clay Fabric Hydration and Flow in Textural Pore Space  

NASA Astrophysics Data System (ADS)

Changes in pore space with hydration state of swelling soils present a challenge to predictive modeling of their hydraulic properties. We developed a pore scale model considering the soil clay fabric as an assembly of idealized colloidal-size tactoids characterized by large surface area associated with the lamellar nature of clays. The arrangement of clay tactoids and the spacing between individual lamellas are functions of clay hydration state quantifiable via the disjoining pressure formalism (DLVO theory) as dominated by a large electrostatic repulsive component. Silt and sand textural components are represented by rigid spheres interspaced by clay fabric in two basic configurations of "expansive" and "reductive" unit cells. Bulk soil properties such as porosity and surface area serve as constraints for the idealized geometry. Total volumetric expansion as a function of water content was constrained by experimentally based universal relationships developed by Giraldez and Sposito. Calculations of mass-volume relationships and soil water characteristics show favorable agreement with measured values. Calculated saturated hydraulic conductivity is within an order of magnitude of experimental data. Work is underway to estimate unsaturated hydraulic conductivity.

Or, D.; Tuller, M.

2001-12-01

160

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

161

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

162

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

163

Measurement of Hydraulic Properties During Constant Flux Infiltration: Field Average  

Microsoft Academic Search

tant for developing, testing, and applying water and solute transport theory. A method of measuring hydraulic conductivity (K ), soil matric fixed depth of soil by integration of the parametric water pressure head (c), and water content (u) relationships is presented. content-depth relationships presented by Broadbridge The procedure uses a series of multipurpose time domain reflectome- and White (1988) for

B. Si; R. G. Kachanoski; F. Zhang; G. W. Parkin; D. E. Elrick

164

Soil Hydraulic Conductivities and their Spatial and Temporal Variations in a Vertisol  

Microsoft Academic Search

Knowledge of soil hydraulic parameters and their spatiotemporal variation is crucial for estimating the water and solute fluxes across the land-atmosphere boundary and within the vadose zone at different scales. The objective of this study was to determine soil hydraulic conductivities (saturated hydraulic conductivity, Ksat, and unsaturated hydraulic conductivity, K(Y)) and their spatial and temporal variations in a clay-dominated biporous

Surajit Das Gupta; Binayak P. Mohanty; J. Maximilian Köhne

2006-01-01

165

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

166

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

NASA Astrophysics Data System (ADS)

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

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

2009-04-01

167

Hydraulic properties of adsorbed water films in unsaturated porous media  

Microsoft Academic Search

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

Tetsu K. Tokunaga

2009-01-01

168

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

Microsoft Academic Search

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

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

1999-01-01

169

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

170

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

171

Influence of soil, land use and climatic factors on the hydraulic conductivity of soil  

NASA Astrophysics Data System (ADS)

Due to inadequate data support, existing algorithms used to estimate soil hydraulic conductivity, K, in (eco)hydrological models ignore the effects of key site factors such as land use and climate and underplay the significant effects of soil structure on water flow at and near saturation. These limitations may introduce serious bias and error into predictions of terrestrial water balances and soil moisture status, and thus plant growth and rates of biogeochemical processes. To resolve these issues, we collated a new global database of hydraulic conductivity measured by tension infiltrometer under field conditions. The results of our analyses on this data set contrast markedly with those of existing algorithms used to estimate K. For example, saturated hydraulic conductivity, Ks, in the topsoil (< 0.3 m depth) was found to be only weakly related to texture. Instead, the data suggests that Ks depends more strongly on bulk density, organic carbon content and land use. In this respect, organic carbon was negatively correlated with Ks, presumably due to water repellency, while Ks at arable sites was, on average, ca. 2-3 times smaller than under natural vegetation, forests and perennial agriculture. The data also clearly demonstrates that clay soils have smaller K in the soil matrix and thus a larger contribution of soil macropores to K at and near saturation.

Jarvis, N.; Koestel, J.; Messing, I.; Moeys, J.; Lindahl, A.

2013-12-01

172

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

173

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

174

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

175

Long-term hydraulic properties of subsurface flow constructed wetlands  

E-print Network

Properties of Subsurface Flow Constructed Wetlands. (December 1994) Glenn Allen Turner, B. S. , University of Southwestern Louisiana Chair of Advisory Committee: Dr. Bruce Lesikai The hydraulic conductivities and porosities of five types of media for use... in subsurface flow constructed wetlands were determined. The media types evaluated were coarse sand, "3/8 inch" pea gravel, "1 inch" river rock, graded "3-5 inch" river rock, and "2 inch" shredded tires (nominal sizes). These hydraulic properties were...

Turner, Glenn Allen

2012-06-07

176

Temporal and spatial (down profile) variability of unsaturated soil hydraulic properties determined from a combination of repeated field experiments and inverse modeling  

NASA Astrophysics Data System (ADS)

An in situ method for estimating parameters necessary for characterizing unsaturated flow in porous media has been applied to 37 individual data sets from the same study site (a sand dune on the edge of a wetland). The measured field data include beginning and ending soil moisture profiles, and continuous records of net surface flux (infiltration/evaporation) and pressure head at the base of the profile. For each study period, the initial profile was used along with the upper and lower boundary conditions to simulate flow and storage changes in the profile from a form of the Richard's equation. Following each model run, the parameters in van Genuchten's characteristic equations were adjusted using the Levenberg-Marquardt procedure. Parameter adjustment and forward modeling continued until a minimum was reached in the difference between measured and simulated moisture profiles. An analysis of the resulting (optimized) parameter estimates indicated that repeated experiments, using the same method, resulted in a very consistent set of parameter values, particularly when parameters were estimated for individual soil layers rather than for the profile as a whole. Statistical analyses of the estimated parameter values indicated that most of the parameters have small coefficients of variability and the mean values are consistent with those generally considered to be valid for uniform sand. The optimization procedure also produced reasonable (and unique) values of saturated moisture content for a buried clayey layer within the otherwise homogeneous deposit of dune sand.

Olyphant, Greg A.

2003-09-01

177

Soil hydraulic conductivity changes caused by irrigation with reclaimed waste water  

SciTech Connect

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

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

1999-10-01

178

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

179

Sensitivity Screening the van Genuchten/Mualem Soil Hydraulic Parameters  

NASA Astrophysics Data System (ADS)

A screening evaluation, including a Morris one-factor-at-a-time (OAT) sensitivity analysis (SA), was performed to evaluate the relative elementary and secondary effects for six of the seven van Genuchten Mualem (VGM) hydraulic model parameters used in predicting water retention and movement through a coarse-textured soil profile under atmospheric boundary conditions. The tortuosity parameter (l) was not evaluated in the OAT analysis because it is generally considered a fitting parameter with little physical significance, and the lack of reliable data concerning the parameters value and distribution as a function of soil texture. Simulated data sets were created based on coarse textural classes using the HYDRUS-1D code, a one dimensional finite element water and solute transport model based on Richards’ equation, to eliminate bias and uncertainty associated with site heterogeneity and measurement error inherent to field data, as well as evapo-transpiration. For each textural class, the simulated data set consisted of hourly estimates of volumetric water content values at 30 and 60 cm soil depths, assuming a homogeneous 100 cm soil profile with atmospheric boundary conditions based on hourly precipitation for the month of February. Initial water distribution profiles were based on average sensor readings for the field site recorded at the beginning of the simulation interval. For the Morris OAT analysis, a set of random input parameter values was chosen from within the upper and lower parameter bounds defined by the extreme 95% confidence intervals reported for coarse-textured soil materials assuming an even parameter distribution. Each parameter was then varied independently consistent with the Morris method. Model results for the new parameter set were then compared to the ideal simulated data for each soil texture, i.e., RSSE. Of the five parameters evaluated, SA indicated that n and ?sat were the most sensitive parameters, and ? was found to be the least.

Seaman, J. C.; Singer, J. H.; Radcliffe, D. E.

2009-12-01

180

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.

181

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...

182

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

183

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 ...

184

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

185

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

E-print Network

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

186

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

187

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

188

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

189

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

Microsoft Academic Search

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

Hans-Holger Liste; Jason C. White

2008-01-01

190

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

191

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

192

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

193

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...

194

CONVERGING PATTERNS OF UPTAKE AND HYDRAULIC REDISTRIBUTION OF SOIL WATER IN CONTRASTING WOODY VEGETATION TYPES  

EPA Science Inventory

We used concurrent measurements of soil water content and soil water potential (Ysoil) to assess the effects of Ysoil on uptake and hydraulic redistribution (HR) of soil water by roots during seasonal drought cycles in six sites characterized by different types and amounts of woo...

195

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

EPA Science Inventory

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

196

Effect of exchangeable Mg on saturated hydraulic conductivity, disaggregation and clay dispersion of disturbed soils  

NASA Astrophysics Data System (ADS)

Different opinions exist regarding the specific effect of Mg on soil physical and chemical properties. We hypothesized that Mg 2+, compared with Ca 2+, reduces saturated hydraulic conductivity ( Ks) via promoting clay swelling, disaggregation, and clay dispersion. Two soils (mixed, mesic Typic Hapludalfs) in packed soil columns were leached with either Ca- or Mg-containing solutions at the successive concentrations of 250, 10, 2, 0.5, and 0 mM. Critical flocculation concentration (CFC) in either Ca or Mg systems was determined with flocculation series tests. Aggregate stability and mean weight diameter (MWD) were assessed by wet-sieving. The CFCs were higher in Mg than in Ca for both soils, indicating that Mg is more dispersive than Ca. The MWDs measured using 1-2 mm aggregates of both soils were significantly larger for Ca-soils than for Mg-soils ( P=0.05). The Ksr (normalized with initial Ks) started to decline at higher concentrations for Mg than for Ca, and the reduction was much greater in Mg than in Ca above 0.5 mM. The Ksr and percent transmittance (inversely related to turbidity) of leachate at a given eluted pore volume following 'steady state' were higher in Ca than in Mg for both soils ( P=0.1), indicating lower permeability and more clay dispersion with the Mg treatment. Swelling and disaggregation, which reduced large pores, appeared to be the dominant process causing the rapid initial decline of Ksr. Clay dispersion and subsequent pore plugging became progressively important when electrolyte concentration was reduced to below CFCs.

Zhang, X. C.; Norton, L. D.

2002-03-01

197

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

198

BIOMASS GROWTH IN UNSATURATED POROUS MEDIA: HYDRAULIC PROPERTIES CHANGES  

Microsoft Academic Search

We present a model to describe the biomass growth process taking place in an unsaturated porous medium during a bioremediation process. We focus on the so-called column experiment. At the initial time biomass and polluted water is inoculated in the column. The subsequent changes of hydraulic properties are analyzed. We also show some preliminary simulations.

I. BORSI; A. FARINA; A. FASANO; M. PRIMICERIO

2006-01-01

199

Laboratory analysis of hydraulic properties of volcanic tuff samples  

SciTech Connect

Daniel B. Stephens and Associates, Inc. (DBS&A) was requested by LANL to perform laboratory analysis for properties of Tuff samples, as outlined in Subcontract No. 9-XT1-X1785-1. The scope of work included conducting the following tasks Sample preparation; Dry bulk density and calculated porosity; Saturated hydraulic conductivity; Moisture characteristics; Air permeability; and Particle density.

NONE

1991-12-04

200

Spatial variability of soil saturated hydraulic conductivity in paddy field in accordance to subsurface percolation  

Microsoft Academic Search

Insufficient puddling with inappropriate implements or imprecise time\\/intensity may alter saturated water flow in paddy soil\\u000a spatially or temporary due to change in aggregate size distribution, dry bulk density, saturated hydraulic conductivity, and\\u000a percolation rate of the soil. In this study, spatial variability of saturated hydraulic conductivity (K\\u000a s), a key parameter of the saturated water flow, in Fuchu Honmachi

K. Wijaya; T. Nishimura; B. I. Setiawan; S. K. Saptomo

2010-01-01

201

Soil water availability and rooting depth as determinants of hydraulic architecture of Patagonian woody species  

Microsoft Academic Search

Adaptations of species to capture limiting resources is central for understanding structure and function of ecosystems. We\\u000a studied the water economy of nine woody species differing in rooting depth in a Patagonian shrub steppe from southern Argentina\\u000a to understand how soil water availability and rooting depth determine their hydraulic architecture. Soil water content and\\u000a potentials, leaf water potentials (?Leaf), hydraulic

Sandra J. Bucci; Fabian G. Scholz; Guillermo Goldstein; Frederick C. Meinzer; Maria E. Arce

2009-01-01

202

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

203

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.

204

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

205

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

PubMed Central

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

Carminati, Andrea; Vetterlein, Doris

2013-01-01

206

Considerations for Modeling Bacterial-Induced Changes in Hydraulic Properties of Variably Saturated Porous Media  

SciTech Connect

Bacterial-induced changes in the hydraulic properties of porous media are important in a variety of disciplines. Most of the pervious research on this topic has focused on liquid-saturated porous media systems that are representative of aquifer sediments. Unsaturated or variably saturated systems such as soils require additional considerations that have not been fully addressed in the literature. This paper reviews some of the earlier studies on bacterial-induced changes in the hydraulic properties of saturated porous media, and discusses characteristics of unsaturated or variably saturated porous media that may be important to consider when modeling such phenomena in these systems. New data are presented from experiments conducted in sand-packed columns with initially steady unsaturated flow conditions that show significant biomass-induced changes in pressure heads and water contents and permeability reduction during growth of a Pseudomonas fluorescens bacterium.

Rockhold, Mark L.; Yarwood, R. R.; Niemet, Michael R.; Bottomley, Peter J.; Selker, John S.

2002-07-26

207

Considerations for modeling bacterial-induced changes in hydraulic properties of variably saturated porous media  

NASA Astrophysics Data System (ADS)

Bacterial-induced changes in the hydraulic properties of porous media are important in a variety of disciplines. Most of the previous research on this topic has focused on liquid-saturated porous media systems that are representative of aquifer sediments. Unsaturated or variably saturated systems such as soils require additional considerations that have not been fully addressed in the literature. This paper reviews some of the earlier studies on bacterial-induced changes in the hydraulic properties of saturated porous media, and discusses characteristics of unsaturated or variably saturated porous media that may be important to consider when modeling such phenomena in these systems. New data are presented from experiments conducted in sand-packed columns with initially steady unsaturated flow conditions that show significant biomass-induced changes in pressure heads and water contents and permeability reduction during growth of a Pseudomonas fluorescens bacterium.

Rockhold, M. L.; Yarwood, R. R.; Niemet, M. R.; Bottomley, P. J.; Selker, J. S.

208

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

E-print Network

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

Paris-Sud XI, Université de

209

Systemic ozone effects on root hydraulic properties in pima cotton  

SciTech Connect

Ambient ozone concentrations have become problematic even in rural, agricultural areas such as the San Joaquin Valley of California. Pima cotton (cv. S6) has been shown to be relatively sensitive to ozone air pollution, at levels occurring in this production area. In this semi-arid area acquisition of water and nutrients may limit yield and biological productivity. Therefore maximal proliferation, exploration, and efficiency of root systems is desirable. Hydraulic conductance provides a parameter to characterize the efficiency of roots and shoots and their interaction. The authors have used a variety of transpiration and pressure vessel techniques to document ozone-induced reduction of root hydraulic conductance in cotton. They hypothesized that these effects are caused by reduced carbohydrate supply due to reduction of photosynthetic capacity of the shoot associated with direct oxidant damage to foliage. However, the authors simulated this reduced photosynthetic capacity by continuously removing leaf area to match that of ozone treated plants. This resulted in a reduction of whole plant biomass similar to ozone-treated plants, but a root/shoot biomass ratio and root hydraulic properties similar to control plants and contrasting with ozone-treated plants. Thus leaf removal did not simulate effects of ozone on root hydraulic properties. A systematic effect of ozone on whole plant function is indicated, perhaps mediated by direct effects on carbohydrate translocation throughout the plant.

Grantz, D.A.; Yang, S. [Univ. of California, Riverside, CA (United States); [Kearney Agricultural Center, Parlier, CA (United States)

1995-12-31

210

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

E-print Network

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

Boyer, Edmond

211

Hydraulic charcterization of carbonatic rock  

Microsoft Academic Search

The hydraulic conductivity, K(theta), and the water retention, theta(h), are needed to predict the flow of water and solute transport in unsaturated porous media. During recent decades methods have been developed to determine these hydraulic properties for rock. We have developed a methodology, based on Wind's evaporation method for soils, to measure in the laboratory the water retention and hydraulic

M. C. Caputo; A. Basile; R. de Mascellis; J. R. Nimmo; M. Vurro; N. Walsh

2003-01-01

212

A combined parameter scaling and inverse technique to upscale the unsaturated hydraulic parameters for heterogeneous soils  

Microsoft Academic Search

Determining a large number of soil hydraulic parameters for heterogeneous soils remains a challenge because inverting for too many parameters can lead to parameter values that are nonunique. Furthermore, such inversions may need very long simulation times, for example, months or more when inverting field-scale problems. In this research, a combined parameter scaling and inverse technique (CPSIT) is proposed to

Z. Fred Zhang; Andy L. Ward; Glendon W. Gee

2004-01-01

213

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

E-print Network

for harvesting most of the soil water, which then flows within the plant vascular system up to the leaves whereOnset of water stress, hysteresis in plant conductance, and hydraulic lift: Scaling soil water] Estimation of water uptake by plants and subsequent water stress are complicated by the need to resolve

Katul, Gabriel

214

Hydraulic redistribution of soil water by roots affects whole-stand evapotranspiration and net ecosystem  

E-print Network

sap flow, soil water content, understory, water potential. Summary � Hydraulic redistribution (HR) of water via roots from moist to drier portions of the soil occurs in many ecosystems, potentially the water potential gradient required for HR is passive, the roots may not passively lose water, as HR

Noormets, Asko

215

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

EPA Science Inventory

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

216

Relating Streamflow Recession to Soil and Watershed Properties  

NASA Astrophysics Data System (ADS)

By exploring the empirical relationship between streamflow recession data from USGS streamgauges and soils data from the Soil Survey Geographic (SSURGO) Database, we test the general hypothesis that a relationship exists between soil properties derived from soil data integrated across a watershed and streamflow recession parameters. This empirical study provides a background for developing a priori parameters with SSURGO soil survey data for parameterizing watersheds for distributed hydrologic modeling and streamflow prediction. Using a random sample of 48 watersheds from across the continental United States, we found a significant correlation between streamflow recession parameters and soil sensitivity, which we define as a combination of hydraulic conductivity, porosity, and soil depth. Our work improves the understanding of streamflow generation processes by exploring how this correlation changes between different geographic regions and climate regimes.

Bandaragoda, C.; Tarboton, D.; Woods, R.; Boettinger, J.

2007-12-01

217

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

218

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

219

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

E-print Network

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

Paris-Sud XI, Université de

220

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

221

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

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

222

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

NASA Astrophysics Data System (ADS)

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

Jana, Raghavendra B.; Mohanty, Binayak P.

2012-02-01

223

MODIFICACIONES DE LA CONDUCTIVIDAD HIDRÁULICA Y POROSIDAD DEL SUELO ESTIMADAS MEDIANTE INFILTRÓMETRO DE DISCO A TENSIÓN Modifications of the hydraulic conductivity and porosity of soil estimated by a tension disc infiltrometer  

Microsoft Academic Search

A B S T R A C T Tension disc infiltrometers are being widely used for determining in situ saturated and near-saturated soil hydraulic properties. The objective of this paper was to characterize modifications of the hydraulic conduc- tivity (K0) and the porosity because of tillage and environmental factors effects, by means of a disc infiltrometer, on a typic Haplustoll

Antonio M. Aoki; Roberto Sereno

224

Microwave Remote Sensing of Soil Moisture for Estimation of Soil Properties  

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

225

From spatial-continuous electrical resistivity measurements to the soil hydraulic functioning at the field scale  

NASA Astrophysics Data System (ADS)

The aim of this article is to present a strategy to interpret the hydraulic functioning of a small field area by using measurements of the soil electrical resistivity. The spatial soil electrical resistivity was recorded at a high resolution on a 2 ha area by the MultiContinous Electrical Profiling (MuCEP) device at two dates. These apparent electrical resistivity measurements were firstly interpreted in terms of local electrical resistivity by 1D inverse modelling to estimate the real resistivity of the soil. These interpreted electrical resistivity data were then transformed into soil water content values and soil water potential values by the use of independent punctual data of water content and the use of the water retention curve determined by laboratory data. Our analysis has permitted us to describe the spatial variability and temporal evolution of the hydraulic functioning at high resolution from electrical resistivity data. The interpretation of the water content and matric potential maps demonstrated that some soil hydraulic processes, such as lateral overland flow, can occur in the studied zone. They would never have been detected by local measurements of soil characteristics or by the use of the soil map.

Cousin, Isabelle; Besson, Arlène; Bourennane, Hocine; Pasquier, Catherine; Nicoullaud, Bernard; King, Dominique; Richard, Guy

2009-10-01

226

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

227

A Particle Smoother with Sequential Importance Resampling for soil hydraulic parameter estimation: A lysimeter experiment  

NASA Astrophysics Data System (ADS)

An adequate description of soil hydraulic properties is essential for a good performance of hydrological forecasts. So far, several studies showed that data assimilation could reduce the parameter uncertainty by considering soil moisture observations. However, these observations and also the model forcings were recorded with a specific measurement error. It seems a logical step to base state updating and parameter estimation on observations made at multiple time steps, in order to reduce the influence of outliers at single time steps given measurement errors and unknown model forcings. Such outliers could result in erroneous state estimation as well as inadequate parameters. This has been one of the reasons to use a smoothing technique as implemented for Bayesian data assimilation methods such as the Ensemble Kalman Filter (i.e. Ensemble Kalman Smoother). Recently, an ensemble-based smoother has been developed for state update with a SIR particle filter. However, this method has not been used for dual state-parameter estimation. In this contribution we present a Particle Smoother with sequentially smoothing of particle weights for state and parameter resampling within a time window as opposed to the single time step data assimilation used in filtering techniques. This can be seen as an intermediate variant between a parameter estimation technique using global optimization with estimation of single parameter sets valid for the whole period, and sequential Monte Carlo techniques with estimation of parameter sets evolving from one time step to another. The aims are i) to improve the forecast of evaporation and groundwater recharge by estimating hydraulic parameters, and ii) to reduce the impact of single erroneous model inputs/observations by a smoothing method. In order to validate the performance of the proposed method in a real world application, the experiment is conducted in a lysimeter environment.

Montzka, Carsten; Hendricks Franssen, Harrie-Jan; Moradkhani, Hamid; Pütz, Thomas; Han, Xujun; Vereecken, Harry

2013-04-01

228

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

Microsoft Academic Search

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

J. J. Drewry; R. J. Paton

2000-01-01

229

Spatial Bias in Field-Estimated Unsaturated Hydraulic Properties  

SciTech Connect

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

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

2000-12-21

230

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

231

Column-scale unsaturated hydraulic conductivity estimates in coarse-textured homogeneous and layered soils derived under steady-state evaporation from a water table  

NASA Astrophysics Data System (ADS)

Steady-state evaporation from a water table has been extensively studied for both homogeneous and layered porous media. For layered media it is of interest to find an equivalent homogeneous medium and define “effective” hydraulic properties. In this paper a new solution for steady-state evaporation from coarse-textured porous media is presented. Based on this solution, the evaporation rate represents a macroscopic (column-scale) measure of unsaturated hydraulic conductivity at the pressure head equal to the maximum extent of the hydraulically connected region above the water table. The presented approach offers an alternative method for determination of unsaturated hydraulic conductivity of homogeneous coarse-textured soils and a new solution for prediction of the effective unsaturated hydraulic conductivity of layered coarse-textured soils. The solution was evaluated with both experimental data and numerical simulations. Comparison with experimental data and numerical results for hypothetically layered soil profiles demonstrate the applicability of the proposed approach for coarse-textured soils.

Sadeghi, Morteza; Tuller, Markus; Gohardoust, Mohammad R.; Jones, Scott B.

2014-11-01

232

Effect of interaggregate capillary cracks on the hydraulic conductivity of swelling clay soils  

NASA Astrophysics Data System (ADS)

Clay soils, as a result of shrinking-swelling, usually have a capillary crack network. The objective of this presentation is to develop a physically based model of the hydraulic conductivity of a swelling clay matrix with interaggregate capillary cracks only. It is based on a number of assumptions relating in the main to the geometrical characteristics of the capillary crack network and the use of the cubic law for water flow in a water-filled slit. The key assumption speaks about the contraction of the interaggregate capillary crack volume in a drying but saturated clay matrix. The expression for vertical hydraulic conductivity of the network of cracks of width hydraulic conductivity of an Israeli clay soil with model predictions of the hydraulic conductivity of an interaggregate capillary crack network in combination with the independent predictions of hydraulic conductivity of the soil matrix available in literature. This comparison demonstrated satisfactory agreement.

Chertkov, V. Y.; Ravina, I.

2001-05-01

233

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

E-print Network

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

Sailhac, Pascal

234

Mechanical and hydraulic properties of rocks related to induced seismicity  

USGS Publications Warehouse

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

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

1977-01-01

235

Effect of Leaching and Gypsum Content on Properties of Gypseous Soil  

E-print Network

Abstract- Gypseous soil is one of problematic soils to be used as foundation of road, building and other structures. It is considerably strong and has good properties when it is dry. The problem appears when constructing heavy buildings or hydraulic structures on these soils after wetted by water from rainfall or from the raising of water table level from any source and leaching the salts from the soil. The primary objective of this paper is to presents the current state of the gypseous soil subject to leaching. A review is provided aiming to discuss the effect of gypsum content and leaching on gypseous soil. T Index Terms- Gypseous soil, Gypsum content, Leaching

Fauziah Ahmad; Md Azlin; Md Said; Lamyaa Najah

236

From spatial-continuous electrical resistivity measurements to the soil hydraulic functioning at the field scale  

Microsoft Academic Search

The aim of this article is to present a strategy to interpret the hydraulic functioning of a small field area by using measurements of the soil electrical resistivity. The spatial soil electrical resistivity was recorded at a high resolution on a 2ha area by the MultiContinous Electrical Profiling (MuCEP) device at two dates. These apparent electrical resistivity measurements were firstly

Isabelle Cousin; Arlène Besson; Hocine Bourennane; Catherine Pasquier; Bernard Nicoullaud; Dominique King; Guy Richard

2009-01-01

237

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

NASA Astrophysics Data System (ADS)

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

Romero, Enrique; Jommi, Cristina

2008-05-01

238

Field-Measured Infiltration Properties of Mojave Desert Soils  

NASA Astrophysics Data System (ADS)

Characteristics typical of alluvial desert soils, such as depositional stratification, desert pavement, biotic crusts, and vesicular horizons strongly influence soil moisture and its variability. Knowledge of infiltration capacity, water retention, and unsaturated hydraulic conductivity is central to the assessment of water availability to plants and animals after infiltration events. These hydraulic parameters are directly related to the degree of soil development. The frequency and magnitude of storm events in conjunction with degree of soil development also affect runoff and erosion. Our purpose is to examine field soil-water behavior and determine unsaturated hydraulic properties needed for large-scale modeling of soil moisture. The results of this study will be used in conjunction with surficial geologic mapping of the Mojave Desert in evaluations of ecological habitat quality. We conducted infiltration/redistribution experiments on three different-aged deposits in the Mojave National Preserve: (1) recently deposited wash sediments, (2) a soil of early Holocene age, and (3) a highly developed soil of late Pleistocene age. In each experiment we ponded water in a 1-m-diameter infiltration ring for 2.3 hr. For several weeks we monitored water content and matric pressure to depths of 1.5 m, and distances of 6 m from the infiltration ring. Measuring techniques included surface electrical resistance tomography, dielectric-constant probes, heat-dissipation probes, and tensiometers. Analysis of the subsurface measurements using an instantaneous-profile technique gives the retention and K properties that will be used in predictive modeling. In each experiment the infiltration rate was nearly constant in time, with infiltration capacity 4 times greater in the youngest than in the oldest soil. Average infiltration flux densities within the ring during the period of ponding were 0.80 m/hr in the active wash, 0.45 m/hr in the Holocene soil, and 0.21 m/hr in the Pleistocene soil. All three deposits have significant gravel (30-70% within the uppermost 1.5 m) with the percentage of silt and clay increasing with deposit age. The low infiltration capacity in the oldest soil is consistent with the presence of the more highly developed vesicular horizon and accumulation of illuvial silt. Depositional stratification in the active wash did not impede downward flow to the same degree as in the early Holocene-age soil, which has some soil horizon development and sparse biotic crust. Infiltrated water spread laterally to at least 1 m beyond the ring perimeter at all sites; the presence of a buried clay-rich horizon in the active wash enhanced spreading at depth to 2 m.

Perkins, K. S.; Nimmo, J. R.; Winfield, K. A.; Schmidt, K. M.; Miller, D. M.; Stock, J. D.; Singha, K.

2005-12-01

239

Estimating hydraulic conductivity of crusted soils using disc infiltrometers and minitensiometers  

Microsoft Academic Search

Although soil crusting has long been recognized as a crucial runoff factor in the Sahel, very few field methods have been developed for the measurement of the crust hydraulic conductivity, which is difficult to achieve because of the small thickness of most surface crusts. A field method, based on the simultaneous use of disc infiltrometers and minitensiometers is proposed for

J.-P. Vandervaere; C. Peugeot; M. Vauclin; R. Angulo Jaramillo; T. Lebel

1997-01-01

240

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 ...

241

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...

242

Field determination of hydraulic conductivity of Norwood silt loam soil  

E-print Network

0) Lal 24 X X I 4. 56 UJ Ci R 48 cLav SILT SAND 60 TABLE 2. Soil-water content (cm /cm ) of Norwood silt loam in equilibrium with several 3 3 applied suctions. Soil depth inches 12 60 103 185 335 517 1034 cm cm cm cm cm cm cm 2 5 15... at the 6, 12, 24, 36, and 48-inch depths, following the initiation of the first 2. 723-inch water appli- cation. The soil surface was not covered with polyethylene film. 44 -50 cP 40 IJI CO Co ICJ -30 CI. K LCI I- & -~0 O th -I 0 5 FIRST...

Saffaf, Adham Yassin

2012-06-07

243

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

244

Terrain attribute soil mapping for predictive continuous soil property maps  

Microsoft Academic Search

The current U.S. Soil Survey information is provided in polygon map units with soil property attributes represented with overlapping ranges between map units. The polygon maps do not represent the soil continuum that conforms to the actual landscape and the soil scientist expert knowledge accumulated during the field survey. Geographic Information System (GIS) technologies and software in combination with high

Zamir Libohova

2010-01-01

245

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

246

Reforesting severely degraded grassland in the Lesser Himalaya of Nepal: Effects on soil hydraulic conductivity and overland flow production  

NASA Astrophysics Data System (ADS)

degraded hillslopes in the Lesser Himalaya challenge local communities as a result of the frequent occurrence of overland flow and erosion during the rainy season and water shortages during the dry season. Reforestation is often perceived as an effective way of restoring predisturbance hydrological conditions but heavy usage of reforested land in the region has been shown to hamper full recovery of soil hydraulic properties. This paper investigates the effect of reforestation and forest usage on field-saturated soil hydraulic conductivities (Kfs) near Dhulikhel, Central Nepal, by comparing degraded pasture, a footpath within the pasture, a 25 year old pine reforestation, and little disturbed natural forest. The hillslope hydrological implications of changes in Kfs with land-cover change were assessed via comparisons with measured rainfall intensities over different durations. High surface and near-surface Kfs in natural forest (82-232 mm h-1) rule out overland flow occurrence and favor vertical percolation. Conversely, corresponding Kfs for degraded pasture (18-39 mm h-1) and footpath (12-26 mm h-1) were conducive to overland flow generation during medium- to high-intensity storms and thus to local flash flooding. Pertinently, surface and near-surface Kfs in the heavily used pine forest remained similar to those for degraded pasture. Estimated monsoonal overland flow totals for degraded pasture, pine forest, and natural forest were 21.3%, 15.5%, and 2.5% of incident rainfall, respectively, reflecting the relative ranking of surface Kfs. Along with high water use by the pines, this lack of recovery of soil hydraulic properties under pine reforestation is shown to be a critical factor in the regionally observed decline in base flows following large-scale planting of pines and has important implications for regional forest management.

Ghimire, Chandra Prasad; Bonell, Mike; Bruijnzeel, L. Adrian; Coles, Neil A.; Lubczynski, Maciek W.

2013-12-01

247

Effect of spatial variability of soil properties on infiltration  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

248

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

249

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

250

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

251

Impact of harvesting and site preparation on physical properties of Piedmont forest soils  

SciTech Connect

The impact of intensive forest management practices on soil bulk density, aeration porosity, and saturated hydraulic conductivity was examined to a depth of 0.3 m before harvest, after harvest, and after site preparation. Harvesting caused significant changes in soil physical properties to an average depth of 0.17 m in whole tree harvest plots and 0.22 m in skid trail plots. Disking was effective in restoring soil physical properties to preharvest levels in the upper 0.07 to 0.12 m of soil. Soil compaction in chop/burn plots may result in reduced root growth because of mechanical impedance, reduced aeration, or both. 21 references.

Gent, J.A. Jr.; Ballard, R.; Hassan, A.E.; Cassel, D.K.

1984-01-01

252

Soil water availability and rooting depth as determinants of hydraulic architecture of Patagonian woody species.  

PubMed

Adaptations of species to capture limiting resources is central for understanding structure and function of ecosystems. We studied the water economy of nine woody species differing in rooting depth in a Patagonian shrub steppe from southern Argentina to understand how soil water availability and rooting depth determine their hydraulic architecture. Soil water content and potentials, leaf water potentials (Psi(Leaf)), hydraulic conductivity, wood density (rho(w)), rooting depth, and specific leaf area (SLA) were measured during two summers. Water potentials in the upper soil layers during a summer drought ranged from -2.3 to -3.6 MPa, increasing to -0.05 MPa below 150 cm. Predawn Psi(Leaf) was used as a surrogate of weighted mean soil water potential because no statistical differences in Psi(Leaf) were observed between exposed and covered leaves. Species-specific differences in predawn Psi(Leaf) were consistent with rooting depths. Predawn Psi(Leaf) ranged from -4.0 MPa for shallow rooted shrubs to -1.0 MPa for deep-rooted shrubs, suggesting that the roots of the latter have access to abundant moisture, whereas shallow-rooted shrubs are adapted to use water deposited mainly by small rainfall events. Wood density was a good predictor of hydraulic conductivity and SLA. Overall, we found that shallow rooted species had efficient water transport in terms of high specific and leaf specific hydraulic conductivity, low rho(w), high SLA and a low minimum Psi(Leaf) that exhibited strong seasonal changes, whereas deeply rooted shrubs maintained similar minimum Psi(Leaf) throughout the year, had stems with high rho(w) and low hydraulic conductivity and leaves with low SLA. These two hydraulic syndromes were the extremes of a continuum with several species occupying different portions of a gradient in hydraulic characteristics. It appears that the marginal cost of having an extensive root system (e.g., high rho(w) and root hydraulic resistance) contributes to low growth rates of the deeply rooted species. PMID:19330355

Bucci, Sandra J; Scholz, Fabian G; Goldstein, Guillermo; Meinzer, Frederick C; Arce, Maria E

2009-07-01

253

Systematic Variability of Soil Hydraulic Conductivity Across Three Vertisol Catenas  

E-print Network

, and conventional iv tillage row crop). Measurement locations were selected to account for variation in terrain attributes. Overall, Ks values were not significantly different across different landscape positions; however, in fields under similar land... Page 1 Soil Apparent Electrical Conductivity (ECa) Maps and Measurements Points of the a.) Improved Pasture, b.) Native Prairie, and c.) Conventional Tillage Catenas ................................................................ 17 2 Elevation...

Rivera, Leonardo Daniel

2011-10-21

254

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

255

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

256

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

E-print Network

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

Holbrook, N. Michele

257

Soil property effects on wind erosion of organic soils  

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

258

Soil fauna, soil properties and geo-ecosystem functioning  

NASA Astrophysics Data System (ADS)

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

Cammeraat, L. H.

2012-04-01

259

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

260

Prediction of Near-Saturated Hydraulic Conductivity in Three Podzolic Boreal Forest Soils  

Microsoft Academic Search

Hintikka, 1972), decrease the density of the surface layers and together with the root channels, increase the Steady-state infiltration fluxes into the soil were measured with a number of large pores. These processes result in the tension infiltrometer at supply potentials of 20.35, 20.70, and 21.10 kPa, and the near-saturated hydraulic conductivities (K ) were calcu- pore system being separated

M. Mecke; C. J. Westman; H. Ilvesniemi

2000-01-01

261

Influence of root mass on saturated hydraulic conductivity in arid soils of central Tunisia  

Microsoft Academic Search

Saturated hydraulic conductivity, Kfs,measured with the inversed auger hole method was related to root mass (living and dead roots) in the uppermost 30 cm of the soil. The studies were carried out in mountain, piedmont and plain areas. Acacia cyanophylla, Eucalyptus occidentals, Pinus halepensis, Atriplex numularia and Opuntia ficus?indica as well as irrigated and non?irrigated almond and olive orchards were

Håkan Petersson; Ingmar Messing; Eliel Steen

1987-01-01

262

Soil Properties That Distinguish Ecological Sites  

E-print Network

Soil Properties That Distinguish Ecological Sites Mike Duniway USGS-Southwest Biological Science of vegetation? Why do sites differ in response to disturbance & management? #12;Ecological Sites & Soil Properties · Within a climatic zone (e.g. MLRA), differentiation of ecological sites based on soil

263

A combined parameter scaling and inverse technique to upscale the unsaturated hydraulic parameters for heterogeneous soils  

NASA Astrophysics Data System (ADS)

Determining a large number of soil hydraulic parameters for heterogeneous soils remains a challenge because inverting for too many parameters can lead to parameter values that are nonunique. Furthermore, such inversions may need very long simulation times, for example, months or more when inverting field-scale problems. In this research, a combined parameter scaling and inverse technique (CPSIT) is proposed to upscale hydraulic parameters from the local scale to the field scale. The CPSIT approach includes two steps: (1) parameter scaling and (2) inverse modeling. In step 1 the number of parameters to be estimated at field scale (FS) is reduced by applying parameter scaling whereby a heterogeneous soil is treated as a composition of multiple equivalent homogeneous media (EHMs). In step 2 the FS parameters for the reference EHM are determined using the inverse technique and observations from well-designed field experiments. The advantages of the CPSIT approach are that the number of parameters to be inverted is reduced by a factor of the number (M) of EHMs, and the simulation time is reduced by a factor of about M2. The CPSIT approach was tested by upscaling the hydraulic parameters using a field injection experiment at the Hanford Site. Results show that when the CPSIT upscaled parameters were used to simulated flow, the mean squared residual was reduced by 83.2% relative to that when the local-scale parameters were used.

Zhang, Z. Fred; Ward, Andy L.; Gee, Glendon W.

2004-08-01

264

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

265

Engineering Properties of NPK Fertilizer Modified Soil  

E-print Network

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

Ezeokonkwo J. C

266

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

E-print Network

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

Adams, Amy Lynn

2011-01-01

267

Hydraulic properties of sphagnum peat moss and tuff (scoria) and their potential effects on water availability  

Microsoft Academic Search

The potential rate of water and nutrient supply to plant roots depends on the hydraulic properties of the container medium (growth medium, substrate), primarily on its unsaturated hydraulic conductivity, which is a measure of the medium's resistance to water flow. Water availability to plants grown in containers is usually being evaluated using criteria based exclusively on water characteristic curves of

F. F. Silva; R. Wallach; Y. Chen

1993-01-01

268

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

269

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

SciTech Connect

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

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

1989-01-01

270

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

NASA Astrophysics Data System (ADS)

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

Khoury, Charbel N.

271

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

272

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

273

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

PubMed

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

Gonzalez-Dugo, Victoria

2010-08-01

274

An iterative calculation for determining formation and fracture properties in hydraulically fractured reservoirs  

E-print Network

AN ITERATIVE CALCULATION FOR DETERMINING FORMATION AND FRACTURE PROPERTIES IN HYDRAULICALLY FRACTURED RESERVOIRS A Thesis by STEPHEN RHETT GIST Submitted to the Graduate College of Texas A R M University In Partial Fulfillment... of the Requirement for the Degree of Master of Science May 1984 Major Subject: Petroleum Engineering AN ITERATIVE CALCULATION FOR DETERMINING FORMATION AND FRACTURE PROPERTIES IN HYDRAULICALLY FRACTURED RESERVOIRS A Thesis by STEPHEN RHETT GIST Approved...

Gist, Stephen Rhett

2012-06-07

275

Estimating the water retention curve from soil properties: comparison of linear, nonlinear and concomitant variable methods  

Microsoft Academic Search

The unsaturated soil hydraulic functions involving the soil–water retention curve (SWRC) and the hydraulic conductivity provide useful integrated indices of soil quality. Existing and newly devised methods were used to formulate pedotransfer functions (PTFs) that predict the SWRC from readily available soil data. The PTFs were calibrated using a large soils database from Hungary. The database contains measured soil–water retention

Kálmán Rajkai; Sándor Kabos; M. Th. van Genuchten

2004-01-01

276

PROPRIEDADES FÍSICAS DO SOLO, INFLUENCIADAS PELA DISTRIBUIÇÃO DE POROS, DE SEIS CLASSES DE SOLOS DA REGIÃO DE LAVRAS-MG 1 Soil physical properties, influenced by pores distribution, of six soil classes in the region of Lavras-MG  

Microsoft Academic Search

The soil pores distribution conditions its physical-hydraulic behavior. Therefore, it influences the dynamic processes of air and solution of the soil, and also its agricultural potentiality. This work aimed at evaluating the influence of pores distribution on physical properties of six classes of soil, under natural vegetation, located in the region of Lavras (MG). Disturbed and undisturbed samples were collected

Kátia Daniela Ribeiro; Stélio Maia Menezes; Maria da Glória; Bastos de Freitas Mesquita; Fabrício de Menezes

277

Effects of surfactants and electrolyte solutions on the properties of soil  

Microsoft Academic Search

Biosurfactants are frequently used in petroleum hydrocarbon and dense non-aqueous phase liquids (DNAPLs) remediation. The\\u000a applicability of biosurfactant use in clayey soils requires an understanding and characterization of their interaction. Comprehensive\\u000a effects of surfactants and electrolyte solutions on kaolinite clay soil were investigated for index properties, compaction,\\u000a strength characteristics, hydraulic conductivities, and adsorption characteristics. Sodium dodecyl sulfate (SDS) and NaPO3

Cumaraswamy Vipulanandan; Jee Woong Kim; Myoung Hak Oh

2006-01-01

278

Estimating hydraulic conductivity of a sandy soil under different plant covers using minidisk infiltrometer and a dye tracer experiment  

Microsoft Academic Search

The objective of this study was to estimate the hydraulic conductivity of sandy soil under different plant cover at the locality\\u000a Mláky II at Sekule (southwest Slovakia). Two sites were demarcated at the locality, with mainly moss species at glade site,\\u000a and pine forest at forest site. The estimation of unsaturated hydraulic conductivity was conducted by (a) minidisk infiltrometer\\u000a and

Marián Homolák; Jozef Capuliak; Viliam Pichler; ?ubomír Lichner

2009-01-01

279

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

SciTech Connect

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

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

2008-01-01

280

Distributed Soil Moisture Estimation in a Mountainous Semiarid Basin: Constraining Soil Parameter Uncertainty through Field Studies  

Microsoft Academic Search

A common practice in distributed hydrological modeling is to assign soil hydraulic properties based on coarse textural datasets. For semiarid regions with poor soil information, the performance of a model can be severely constrained due to the high model sensitivity to near-surface soil characteristics. Neglecting the uncertainty in soil hydraulic properties, their spatial variation and their naturally-occurring horizonation can potentially

S. Yatheendradas; E. Vivoni

2007-01-01

281

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

282

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

283

A Statistical Model for Predicting Unsaturated Hydraulic Properties of Deep Sediments at the Idaho National Engineering and Environmental Laboratory  

NASA Astrophysics Data System (ADS)

The development and application of property-transfer functions is an important approach for predicting unsaturated hydraulic properties from more easily measured bulk properties. At the Idaho National Engineering and Environmental Laboratory (INEEL), the unsaturated zone is comprised of thick basalt flow sequences interbedded with thinner sedimentary layers. Buried hazardous waste in the surficial soil is a possible source of contamination to the underlying Snake River Plain aquifer, which can be as deep as 200 m below land surface. Determining the unsaturated hydraulic properties of the sedimentary layers is one step in understanding water flow and solute transport processes through this complex unsaturated system. This study uses multiple linear regression analysis to construct simple property-transfer functions for estimating the water retention curve for deep sediments at the INEEL. The regression models were developed using laboratory measurements on 109 sediment core samples collected at depths of 9 m to 175 m at two facilities within the southwestern portion of the INEEL. These data included water retention measurements, the curve fit parameters for which are the dependent variables of the property-transfer functions, and bulk properties (such as bulk density and various representations of the particle-size distribution), which are the potential independent variables. The Rossi-Nimmo junction model was used to represent the water retention measurements. Three parameters define this retention curve model: 1) saturated water content (? sat), 2) a scaling parameter for matric pressure (? o), and 3) a curve shape parameter (? ). The bulk property data and optimized hydraulic parameter values were used to develop a separate regression model for each parameter. The predicted parameters were then used to calculate the water retention curve from saturation to oven dryness. A selection process for the independent variables, referred to as "all possible subsets regression," was used to determine the best predictive model for each hydraulic parameter. Preliminary regression results show that textural class percentages were consistently better able to explain the hydraulic parameters than were other potential representations of the particle-size distribution. The adjusted coefficient of determination (adjusted R2) for the best models, which consisted of some linear combination of textural class percentages and bulk density, ranged between 0.2 and 0.5 when all observations were included in the regression analyses. The residuals were close to normally distributed and were fairly homoscedastic when plotted versus the predicted dependent variable values. The low adjusted R2 values may indicate that the bulk property data used in calibrating the models are not sufficient to completely predict the hydraulic parameters or may indicate significant measurement errors in the dependent or independent variables. Other bulk property data not available for calibrating the property-transfer functions, such as mineralogy, specific surface areas, or adsorption capacities, might correlate more strongly with the hydraulic parameters, and thus may be useful in future regression analyses. The property-transfer functions from this study provide a basis for development of a theoretical model that relies on physical relationships between the pore-size distribution and the bulk properties of the media and that should be more universal in its application throughout the INEEL and other geographic locations.

Winfield, K. A.; Nimmo, J. R.

2003-12-01

284

High-quality unsaturated zone hydraulic property data for hydrologic applications  

USGS Publications Warehouse

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

Perkins, K.; Nimmo, J.

2009-01-01

285

High-quality unsaturated zone hydraulic property data for hydrologic applications  

NASA Astrophysics Data System (ADS)

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

Perkins, Kim; Nimmo, John

2009-07-01

286

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

287

Physical and hydraulic properties of volcanic rocks from Yucca Mountain, Nevada  

USGS Publications Warehouse

A database of physical and hydraulic properties was developed for rocks in the unsaturated zone at Yucca Mountain, Nevada, a site under consideration as a geologic repository for high-level radioactive waste. The 5320 core samples were collected from 23 shallow (<100 m) and 10 deep (500-1000 m) vertical boreholes. Hydrogeologic units have been characterized in the unsaturated zone [Flint, 1998] that represent rocks with ranges of welding, lithophysae, and high and low temperature alteration (as a result of the depositional, cooling, and alterational history of the lithostratigraphic layers). Lithostratigraphy, the hydrogeologic unit, and the corresponding properties are described. In addition, the physical properties of bulk density, porosity, and particle density; the hydraulic properties of saturated hydraulic conductivity and moisture retention characteristics; and the field water content were measured and compiled for each core sample.

Flint, L. E.

2003-01-01

288

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

PubMed

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

Kuráz, V

2001-01-01

289

Nitrogen Dynamics in the Soil-Root-Plant Continuum: Competitive and Mutualistic Dependencies through Hydraulic Redistribution  

NASA Astrophysics Data System (ADS)

Below ground processes occurring in natural ecosystems such as root water uptake and hydraulic redistribution (HR) have significant influence on the water dynamics. However, the real implications of these processes in the cycling of biogeochemical elements as N or P remain unknown. HR is a process by which plant roots are able to transport water passively in the soil column. Due to the capacity of HR to influence soil moisture and soil temperature it is believed that the presence of HR influences the rates of mineralization and ion diffusion in the soil enhancing nutrient uptake by plants. Furthermore, there is experimental evidence that HR enhances the interaction between species by facilitation of water from deeper to shallow rooted plants. Thus HR could also influence plant nutrient uptake in some species by facilitating a pathway from other species. In this study we use a numerical model to analyze the effects of HR on the N dynamics in the soil. We examine the effect of HR in decomposition of organic matter and passive transport of nitrogen in the soil column including plant uptake and leaching. We analyze the dynamics under two different cases of species composition (single or multiple species) to understand the nitrogen cycling in the presence of multiple plant species that coexist and the capacity of HR to enhance these dynamics. The model used in this study is multi species MLCan which is a multi-layer above- and below-ground soil-root-canopy model that is able to simulate species interaction using a "shared resource" conceptualization. MLCan is coupled with a C:N model (1) where only two pools of soil carbon, namely soil organic matter and microorganisms, are considered and soil N dynamics are calculated based on C:N ratio formulations. The forcing data is obtained from the Ameriflux Tower located in Blodgett Forest, Sierra Nevada, California. Three plant species are considered. We found that HR enhances the mineralization of organic matter at the surface. However in deeper layers the increment in soil moisture is compensated by the increment in soil temperature when HR is absent producing a higher mineralization in the absence of HR. Thus, apart from the near-surface there is a higher content of organic matter in the presence of HR. In the absence of HR, nitrogen uptake occurs mainly in deeper layers leading to an accumulation of nitrate at the bottom of the soil column that enhance leaching. In the presence of HR the uptake of nitrate occurs in shallower layers and leaching of nitrogen is reduced. When understory species were present the nitrogen uptake in the overstory species increased because the C:N ratio from litter of the understory vegetation that fix nitrogen was smaller. Further, the nitrogen uptake in the understory species was facilitated by overstory species that enhance water uptake through HR and, therefore, nitrate transport. (1) Manzoni, S., and A. Porportato. A theoretical analysis of nonlinearities and feedbacks in soil carbon and nitrogen cycles. Soil Biology & Biochemistry. 2007

Quijano, J. C.; Kumar, P.; Drewry, D. T.

2011-12-01

290

Prediction of soil properties using fuzzy membership values  

Microsoft Academic Search

Detailed information on the spatial variation of soils is desirable for many agricultural and environmental applications. This research explores three approaches that use soil fuzzy membership values to predict detailed spatial variation of soil properties. The first two are weighted average models with which the soil property value at a location is the average of the typical soil property values

A-Xing Zhu; Feng Qi; Amanda Moore; James E. Burt

2010-01-01

291

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

292

New Conceptual Model for Soil Treatment Units: Formation of Multiple Hydraulic Zones during Unsaturated Wastewater Infiltration.  

PubMed

Onsite wastewater treatment systems are commonly used in the United States to reclaim domestic wastewater. A distinct biomat forms at the infiltrative surface, causing resistance to flow and decreasing soil moisture below the biomat. To simulate these conditions, previous modeling studies have used a two-layer approach: a thin biomat layer (1-5 cm thick) and the native soil layer below the biomat. However, the effect of wastewater application extends below the biomat layer. We used numerical modeling supported by experimental data to justify a new conceptual model that includes an intermediate zone (IZ) below the biomat. The conceptual model was set up using Hydrus 2D and calibrated against soil moisture and water flux measurements. The estimated hydraulic conductivity value for the IZ was between biomat and the native soil. The IZ has important implications for wastewater treatment. When the IZ was not considered, a loading rate of 5 cm d resulted in an 8.5-cm ponding. With the IZ, the same loading rate resulted in a 9.5-cm ponding. Without the IZ, up to 3.1 cm d of wastewater could be applied without ponding; with the IZ, only up to 2.8 cm d could be applied without ponding. The IZ also plays a significant role in soil moisture distribution. Without the IZ, near-saturation conditions were observed only within the biomat, whereas near-saturation conditions extended below the biomat with the IZ. Accurate prediction of ponding is important to prevent surfacing of wastewater. The degree of water and air saturation influences pollutant treatment efficiency through residence time, volatility, and biochemical reactions. PMID:24216371

Geza, Mengistu; Lowe, Kathryn S; Huntzinger, Deborah N; McCray, John E

2013-07-01

293

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

Microsoft Academic Search

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

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

1995-01-01

294

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

295

Soil Properties as Influenced by Dust Emissions  

NASA Astrophysics Data System (ADS)

Wind erosion selectively removes the most fertile portion of the soil. When sediment balance from wind erosion is negative, soil quality is impoverished. Our objective was to determine the change in selected soil properties that are measures of soil quality as influenced by dust emissions from wind erosion. We sampled saltation drifts and near surface bulk soil from several recently eroded fields, measured selected soil properties, and compared results from the eroded saltation drifts with the non-eroded bulk soil. We found that sandy loams became loamy sands and loamy sands became sands with 10 to 30% increase of sand in the saltation drift with a corresponding decrease in organic matter and cation exchange capacity. Whereas the texture, organic matter, and cation exchange is not benefited by the millions of tons of nutrient and organic matter enriched soil that is deposited in the road ditches, reservoirs, and oceans. In general, wind erosion degrades soil and lowers its capacity to produce food and fiber needed to sustain an increasing population.

Skidmore, E. L.; Tatarko, J.

2003-12-01

296

Tropical residual soil as compacted soil liners  

Microsoft Academic Search

A series of laboratory tests was conducted on a tropical residual soil, which is widespread and readily available over a considerable part of Peninsular Malaysia, to assess whether it could be compacted as hydraulic barriers in waste disposal landfills. Index properties, swelling potential, cation exchange capacity (CEC), compaction characteristics, and hydraulic conductivity of the soil indicate that it is inorganic,

M. R. Taha; M. H. Kabir

2005-01-01

297

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

298

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

299

The capacity for nitrate regulation of root hydraulic properties correlates with species’ nitrate uptake rates  

Microsoft Academic Search

A mechanism whereby water flow towards root surfaces is stimulated when exposed to nutrient patches may be evolutionarily\\u000a desirable in environments with heterogeneous soils. Indeed, the presence of nitrate has been shown to increase root hydraulic\\u000a conductance in a few agricultural species characterized by high nitrate demand. Does a similar stimulation of root conductivity\\u000a in response to external nitrate addition

Anna Górska; Jillian W. Lazor; Anna K. Zwieniecka; Christopher Benway; Maciej A. Zwieniecki

2010-01-01

300

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

301

UNSATURATED SOIL HYDRAULIC PROPERTIES FROM REDISTRIBUTION OF INJECTED WATER  

EPA Science Inventory

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

302

Outflow methods for evaluating the soil hydraulic functional relationships between NAPL pressure and saturation in porous media  

SciTech Connect

Remediation and cleanup of petroleum product contaminated ground water often require modeling of fluid transport processes when immiscible liquid phases are present. Modeling of such multiphase transport systems requires knowledge of the functional relationships between fluid pressures, saturations, and permeabilities. The authors evaluated the applicability of the multistep outflow method used in soil science to determine these functions for two porous media (loam and sand) using Soltrol 130 and water as wetting fluids. The analytical retention and permeability functions of van Genuchten and Mualem were used, with an inverse method that has been shown to be reliable in estimating water retention and unsaturated hydraulic conductivity in soils, to estimate soil hydraulic function parameters for Soltrol 130 and water. The water and Soltrol 130 cumulative drainage as a function of time and the equilibrium saturations were used as input to a numerical model (MLSTPM) to optimize, through an inverse solution of the Richards equation, the parameters needed for the hydraulic functions. Optimizations were carried out for saturation paths corresponding to monotonically decreasing wetting phase saturations only. The functional relationships between oil pressures, saturations, and permeabilities in Oso-Flaco fine sand were accurately predicted from the optimized water retention curve parameters based on scaling by the ratio of interfacial tensions. However, this scaling procedure was inadequate to predict oil hydraulic function parameters from those of water in Yolo loam.

Bali, K.M. [Univ. of California Desert Research and Extension Center, Holtville, CA (United States); Grismer, M.E.; Hopmans, J.W. [Univ. of California, Davis, CA (United States). Dept. of Land, Air, and Water Resources

1996-12-31

303

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...

304

A Network Modeling Approach to Derive Unsaturated Hydraulic Properties of a Rough-Walled Fracture  

Microsoft Academic Search

The hydraulic properties of a rough-walled fracture in a limestone sample are estimated using a network model based on three-dimensional representations of the fracture apertures. Two different scenarios are considered: drainage of water out of a fracture and infiltration of water into a fracture. Besides capillary effects, the model takes into account an accessibility criterion (invasion percolation) and, in the

Katrijn Vandersteen; Jan Carmeliet; Jan Feyen

2003-01-01

305

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

E-print Network

in fluid flow and chemical transport is critical for the oil and gas, waste disposal and deep storage a major influence on deep flow systems. Fault hydraulic properties vary considerably over both space associated with (1) structural architecture of faults and (2) confining pressure. We then model flow through

Cowie, Patience

306

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

307

Quasi-steady centrifuge method for unsaturated hydraulic properties  

NASA Astrophysics Data System (ADS)

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.

Caputo, Maria C.; Nimmo, John R.

2005-11-01

308

Crop Productivity and Surface Soil Properties of a Severely Wind-Eroded Soil  

Microsoft Academic Search

Wind erosion degrades soil quality by modifying soil properties important for optimum plant growth and productivity. In this study we evaluated soil properties and plant productivity of an Amarillo fine sandy loam soil that had been severely wind-eroded for 9 years, causing a loss of about 10 cm (over 1300 mt ha -1 ) of the soil surface. Cotton, kenaf,

T. M. Zobeck; J. D. Bilbro

309

Estimating the Effective Soil Temperature at L-Band as a Function of Soil Properties  

Microsoft Academic Search

To retrieve soil moisture from L-band microwave radiometry, it is necessary to account for the effects of temperature within both vegetation and soil media. To compute the effective soil temperature TG, several simple formulations accounting for soil temperatures at the surface and at depth and surface soil moisture have been developed. However, the effects of the soil physical properties in

Jean-Pierre Wigneron; André Chanzy; Patricia de Rosnay; Christoph Rudiger; Jean-Christophe Calvet

2008-01-01

310

Comprehensive experimental studies were conducted as part of this project in order to evaluate the unsaturated hydraulic and shear strength properties of Eagle Ford clay. The clay was subjected to cycles of wetting and  

E-print Network

softened shear strength is also applicable to compacted slopes of high plasticity clays and shales exposed a series of evaporation and infiltration experiments conducted to determine the effect of cracking program to determine the effect of cracking on the hydraulic properties of the soil. Additional tests were

Zornberg, Jorge G.

311

ALTERNA TIVA P ARA CARACTERIZAÇÃO DA CONDUTIVIDADE HIDRÁULICA SATURADA DO SOLO UTILIZANDO PROBABILIDADE DE OCORRÊNCIA Alternative of characterization to the soil hydraulic conductivity utilizing probability of occurrence  

Microsoft Academic Search

The Saturated Hydraulic Conductivity of the soil (Ksat) due to its importance in inform about the capacity of transport of water, solutes and chemical substances in the soil should be well characterized, since in general, this value is used in calculations of flows in the soil. Aiming at proposing an alternative to characterize the Ksat, starting from a series of

Maria da Glória; Bastos de Freitas Mesquita; Sérgio Oliveira Moraes; Fernanda Peruchi; Maria de Carvalho Terez

312

Mineralogical and physical properties of residual soils developed on basalts and limestones in temperate and tropical climatic regions  

Microsoft Academic Search

The weathering of rocks under temperate and tropical climatic conditions produces marked differences in mineralogy and in a number of other physical and engineering properties of the residual soils. These include features such as the hydraulic conductivity, bulk density, Atterberg Limits, grain size distribution, and surface area of the respective clay phases. The more intensive weathering (laterization) that takes place

W. C. Isphording; R. B. Jackson

1994-01-01

313

Estimating the saturated hydraulic conductivity in a spatially variable soil with different permeameters: a stochastic Kozeny–Carman relation  

Microsoft Academic Search

The spatial variability of the saturated hydraulic conductivity (Ks) of a greenhouse banana plantation volcanic soil was investigated with three different permeameters: (a) the Philip-Dunne field permeameter, an easy to implement and low cost device; (b) the Guelph field permeameter; (c) the constant head laboratory permeameter. Ks was measured on a 14×5 array of 2.5m×5m rectangles at 0.15m depth using

Carlos M. Regalado; Rafael Muñoz-Carpena

2004-01-01

314

Beyond Plants Indicators and Soil Surface Properties in  

E-print Network

­ Liaison to ARS USDA-NRCS Las Cruces, NM #12;Soil degradation can affect: · Plant production, reproductionBeyond Plants ­ Indicators and Soil Surface Properties in STM's Arlene Tugel Soil Scientist degradation · Indicator: "A soil or plant property that is sensitive to change." · Reflects complex processes

315

Relating Streamflow Recession to Soil and Watershed Properties  

Microsoft Academic Search

By exploring the empirical relationship between streamflow recession data from USGS streamgauges and soils data from the Soil Survey Geographic (SSURGO) Database, we test the general hypothesis that a relationship exists between soil properties derived from soil data integrated across a watershed and streamflow recession parameters. This empirical study provides a background for developing a priori parameters with SSURGO soil

C. Bandaragoda; D. Tarboton; R. Woods; J. Boettinger

2007-01-01

316

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

E-print Network

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

Boyer, Edmond

317

Numerical evaluation of effective unsaturated hydraulic properties for fractured rocks  

SciTech Connect

To represent a heterogeneous unsaturated fractured rock by its homogeneous equivalent, Monte Carlo simulations are used to obtain upscaled (effective) flow properties. In this study, we present a numerical procedure for upscaling the van Genuchten parameters of unsaturated fractured rocks by conducting Monte Carlo simulations of the unsaturated flow in a domain under gravity-dominated regime. The simulation domain can be chosen as the scale of block size in the field-scale modeling. The effective conductivity is computed from the steady-state flux at the lower boundary and plotted as a function of the averaging pressure head or saturation over the domain. The scatter plot is then fitted using van Genuchten model and three parameters, i.e., the saturated conductivity K{sub s}, the air-entry parameter {alpha}, the pore-size distribution parameter n, corresponding to this model are considered as the effective K{sub s}, effective {alpha}, and effective n, respectively.

Lu, Zhiming [Los Alamos National Laboratory; Kwicklis, Edward M [Los Alamos National Laboratory

2009-01-01

318

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

319

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

Microsoft Academic Search

A hydrostructural domain approach was tested and validated in fractured bedrock aquifers of the Gulf Islands, British Columbia\\u000a (BC), Canada. Relative potential hydraulic properties for three hydrostructural domains in folded and faulted sedimentary\\u000a rocks were derived using stochastically generated fracture data and hybrid discrete fracture network-equivalent porous media\\u000a (DFN-EPM) modelling. Model-derived relative potential transmissivity values show good spatial agreement with

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

2008-01-01

320

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...

321

Inverse Method for Estimating the Spatial Variability of Soil Particle Size Distribution from Observed Soil Moisture  

E-print Network

Observed Soil Moisture Feifei Pan1 ; Christa D. Peters-Lidard2 ; and Anthony W. King3 Abstract: Soil.g., drainage, runoff, soil moisture, evaporation, and evapo- transpiration. With information about soil PSD, we can estimate almost all soil hydraulic properties e.g., saturated soil moisture, field capacity

Pan, Feifei

322

Impact of Sub-grid Soil Textural Properties on Simulations of Hydrological Fluxes at the Continental Scale Mississippi River Basin  

NASA Astrophysics Data System (ADS)

Knowledge of soil hydraulic properties such as porosity and saturated hydraulic conductivity is required to accurately model the dynamics of near-surface hydrological processes (e.g. evapotranspiration and root-zone soil moisture dynamics) and provide reliable estimates of regional water and energy budgets. Soil hydraulic properties are commonly derived from pedo-transfer functions using soil textural information recorded during surveys, such as the fractions of sand and clay, bulk density, and organic matter content. Typically large scale land-surface models are parameterized using a relatively coarse soil map with little or no information on parametric sub-grid variability. In this study we analyze the impact of sub-grid soil variability on simulated hydrological fluxes over the Mississippi River Basin (?3,240,000 km2) at multiple spatio-temporal resolutions. A set of numerical experiments were conducted with the distributed mesoscale hydrologic model (mHM) using two soil datasets: (a) the Digital General Soil Map of the United States or STATSGO2 (1:250 000) and (b) the recently collated Harmonized World Soil Database based on the FAO-UNESCO Soil Map of the World (1:5 000 000). mHM was parameterized with the multi-scale regionalization technique that derives distributed soil hydraulic properties via pedo-transfer functions and regional coefficients. Within the experimental framework, the 3-hourly model simulations were conducted at four spatial resolutions ranging from 0.125° to 1°, using meteorological datasets from the NLDAS-2 project for the time period 1980-2012. Preliminary results indicate that the model was able to capture observed streamflow behavior reasonably well with both soil datasets, in the major sub-basins (i.e. the Missouri, the Upper Mississippi, the Ohio, the Red, and the Arkansas). However, the spatio-temporal patterns of simulated water fluxes and states (e.g. soil moisture, evapotranspiration) from both simulations, showed marked differences; particularly at a shorter time scale (hours to days) in regions with coarse texture sandy soils. Furthermore, the partitioning of total runoff into near-surface interflows and baseflow components was also significantly different between the two simulations. Simulations with the coarser soil map produced comparatively higher baseflows. At longer time scales (months to seasons) where climatic factors plays a major role, the integrated fluxes and states from both sets of model simulations match fairly closely, despite the apparent discrepancy in the partitioning of total runoff.

Kumar, R.; Samaniego, L. E.; Livneh, B.

2013-12-01

323

Field Measurement of Saturated Hydraulic Conductivity at the Hillslope Scale under different Soil Series and Management Practices  

NASA Astrophysics Data System (ADS)

Heterogeneity of saturated hydraulic conductivity (Ksat) was investigated at the hillslope scale in the South Amana Subwatershed (SAS), IA. Three fields of different soil series, and management practices (tilled, no-till, CRP) were examined at the SAS. Ksat was measured using 30 semi-automated double ring infiltrometer. Soil cores were also collected in the vicinity of the Ksat measurements via a truck-mounted Giddings Probe. Core sample analysis suggests that the spatial variability in Ksat very much reflects the overall soil texture variability found in the tested fields. The spatial variability of Ksat was log-normally distributed, which closely follows the distribution of the surface microroughness. Ksat varied over 3-orders of magnitude within the tested fields. The high sensitivity of Ksat was a good index to identify soil heterogeneity. Comparison between the published soil maps and observed soil series of the collected cores shows that erosion to varying degrees has occurred along the hillslope. Along the sides of the hillslope as we move downhill, the loam layer was found much deeper than along the centerline of the hillslope. This finding was indicative that significant erosion has occurred along the centerline of the hillslope. An outcome of the severe erosion was that the soil texture differed between the centerline and the sides. This different texture was found to affect Ksat at similar slope positions and land cover.

Elhakeem, M.; Chang, Y.; Wilson, C. G.; Papanicolaou, T.

2009-12-01

324

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

325

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

326

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

NASA Astrophysics Data System (ADS)

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

Hjerne, Calle; Nordqvist, Rune

2014-09-01

327

Rheological Properties of Wet Soils and Clays under Steady and Oscillatory Stresses  

Microsoft Academic Search

In engineering soil mechanics, it is very common to determine stress-strain relationship of soils (under equi- Tilled agricultural soils are in a constant state of change induced librium conditions) empirically from simultaneous mea- by variations in soil strength due to wetting and drying and compaction by farm implements. Changes in soil structure affect many hydraulic surements of stress and strain,

Teamrat A. Ghezzehei; Dani

2001-01-01

328

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

NASA Astrophysics Data System (ADS)

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

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

2009-04-01

329

Comparison of empirical, semi-empirical and physically based models of soil hydraulic functions derived for bi-modal soils  

Microsoft Academic Search

The accelerated flow in soil pores is responsible for a rapid transport of pollutants from the soil surface to deeper layers up to groundwater. The term preferential flow is used for this type of transport. Our study was aimed at the preferential flow realized in the structural porous domain in bi-modal soils. We compared equations describing the soil water retention

M. Kutílek; L. Jendele; M. Krejca

2009-01-01

330

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

331

Hydraulic and mechanical properties of young Norway spruce clones related to growth and wood structure  

PubMed Central

Summary Stem segments of eight five-year-old Norway spruce (Picea abies (L.) Karst.) clones differing in growth characteristics were tested for maximum specific hydraulic conductivity (ks100), vulnerability to cavitation and behavior under mechanical stress. The vulnerability of the clones to cavitation was assessed by measuring the applied air pressure required to cause 12 and 50% loss of conductivity (?12, ?50) and the percent loss of conductivity at 4 MPa applied air pressure (PLC4MPa). The bending strength and stiffness and the axial compression strength and stiffness of the same stem segments were measured to characterize wood mechanical properties. Growth ring width, wood density, latewood percentage, lumen diameter, cell wall thickness, tracheid length and pit dimensions of earlywood cells, spiral grain and microfibril angles were examined to identify structure–function relationships. High ks100 was strongly and positively related to spiral grain angle, which corresponded positively to tracheid length and pit dimensions. Spiral grain may reduce flow resistance of the bordered pits of the first earlywood tracheids, which are characterized by rounded tips and an equal distribution of pits along the entire length. Wood density was unrelated to hydraulic vulnerability parameters. Traits associated with higher hydraulic vulnerability were long tracheids, high latewood percentage and thick earlywood cell walls. The positive relationship between earlywood cell wall thickness and vulnerability to cavitation suggest that air seeding through the margo of bordered pits may occur in earlywood. There was a positive phenotypic and genotypic relationship between ks100 and PLC4MPa, and both parameters were positively related to tree growth rate. Variability in mechanical properties depended mostly on wood density, but also on the amount of compression wood. Accordingly, hydraulic conductivity and mechanical strength or stiffness showed no tradeoff. PMID:17472942

ROSNER, SABINE; KLEIN, ANDREA; MULLER, ULRICH; KARLSSON, BO

2011-01-01

332

Hydraulic and mechanical properties of young Norway spruce clones related to growth and wood structure.  

PubMed

Stem segments of eight five-year-old Norway spruce (Picea abies (L.) Karst.) clones differing in growth characteristics were tested for maximum specific hydraulic conductivity (k(s100)), vulnerability to cavitation and behavior under mechanical stress. The vulnerability of the clones to cavitation was assessed by measuring the applied air pressure required to cause 12 and 50% loss of conductivity (Psi(12), Psi(50)) and the percent loss of conductivity at 4 MPa applied air pressure (PLC(4MPa)). The bending strength and stiffness and the axial compression strength and stiffness of the same stem segments were measured to characterize wood mechanical properties. Growth ring width, wood density, latewood percentage, lumen diameter, cell wall thickness, tracheid length and pit dimensions of earlywood cells, spiral grain and microfibril angles were examined to identify structure-function relationships. High k(s100) was strongly and positively related to spiral grain angle, which corresponded positively to tracheid length and pit dimensions. Spiral grain may reduce flow resistance of the bordered pits of the first earlywood tracheids, which are characterized by rounded tips and an equal distribution of pits along the entire length. Wood density was unrelated to hydraulic vulnerability parameters. Traits associated with higher hydraulic vulnerability were long tracheids, high latewood percentage and thick earlywood cell walls. The positive relationship between earlywood cell wall thickness and vulnerability to cavitation suggest that air seeding through the margo of bordered pits may occur in earlywood. There was a positive phenotypic and genotypic relationship between k(s100) and PLC(4MPa), and both parameters were positively related to tree growth rate. Variability in mechanical properties depended mostly on wood density, but also on the amount of compression wood. Accordingly, hydraulic conductivity and mechanical strength or stiffness showed no tradeoff. PMID:17472942

Rosner, Sabine; Klein, Andrea; Müller, Ulrich; Karlsson, Bo

2007-08-01

333

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

USGS Publications Warehouse

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

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

1989-01-01

334

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

NASA Astrophysics Data System (ADS)

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 are highly complex in soil-based systems but such systems provide a self-sustainable microcosm that potentially offers compactness, low energy demand, near-ambient reactor temperatures and pressure, reliability, forgiveness of operational errors or neglect, and a rich biodiversity of microorganisms, all features which are fundamental for the sustainability and reliability of long-term manned space missions. However, the hydraulics and biogeochemical functioning of soil systems exposed to gravities lower than the Earth’s are still unknown. Since gravity is crucial in driving water flow, hypogravity will affect nutrient and oxygen transport in the liquid and gaseous phases, and could lead to suffocation of microorganisms and roots, and emissions of toxic gases. A highly mechanistic model coupling soil hydraulics and nutrient biogeochemistry previously tested on soils on Earth (g = 9.806 m s-2) is used to highlight the effects of gravity on the functioning of cropping units on Mars (0.38g), the Moon (0.16g), and in the international space station (ISS, nearly 0g). For each scenario, we have compared the net leaching of water, the leaching of NH3, NH4+, NO2- and NO3- solutes, the emissions of NH3, CO2, N2O, NO and N2 gases, the concentrations profiles of O2, CO2 and dissolved organic carbon (DOC) in soil, the pH, and the dynamics of various microbial functional groups within the root zone against the same control variables in the soil under terrestrial gravity. The tested hypo- and micro-gravity resulted in 90-100% lower water leaching rates than the Earth’s, 95-100% lower nutrient leaching rates, and lower emissions of NH3 and NO gases (80-95% and 30-40%, respectively). Lower N loss through leaching resulted in 60-100% higher concentration of microbial biomass, but did not alter the vertical stratification of the microorganisms with respect to the stratification on Earth. However, the higher biomass concentration produced higher emissions of N2O (80%), N2 (200%), and CO2 gases (40%), respectively.

Maggi, F.; Pallud, C. E.

2010-12-01

335

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. PMID:22031578

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

2013-01-01

336

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

337

Soil Properties, Surveys, and Applications GEOG 3220 Fall 2009  

E-print Network

Soil Properties, Surveys, and Applications GEOG 3220 Fall 2009 Dr. Scott Lecce Office: A-235, Elements of the Nature and Properties of Soils Course Description: The purpose of this course is to provide a general introduction to soil science for students interested in environmental studies. It is taught from

Lecce, Scott A.

338

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

Microsoft Academic Search

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

J. H. Richards; M. M. Caldwell

1987-01-01

339

Applied Soil Ecology 14 (2000) 89101 Relationships between abiotic and biotic soil properties during fallow  

E-print Network

. Introduction Chemical fertility and physical stability of sandy soils in West Africa are low (Sanchez and LoganApplied Soil Ecology 14 (2000) 89­101 Relationships between abiotic and biotic soil properties 2000; accepted 9 February 2000 Abstract Relationships between soil characteristics, various forms

Thioulouse, Jean

340

Field scale soil characterization using pedostructural properties  

Microsoft Academic Search

Accurate soil characterization is crucial for understanding soil-water interactions and allow for better on-farm agricultural and environmental management. Current soil characterization methods lack quantitative attributes that integrate the soil mapping units with environmental and agronomical models. In this research we propose a methodology to physically characterize the soil water medium using quantitative parameters. We incorporated the continuously measured soil water

Mohammed Ali Salahat

2006-01-01

341

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

342

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

SciTech Connect

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

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

1992-12-01

343

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

PubMed Central

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

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

2014-01-01

344

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

PubMed

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

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

2014-08-01

345

Photoinhibition of stem elongation by blue and red light. Effects on hydraulic and cell wall properties  

SciTech Connect

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 (lay 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. (Hebrew Univ., Jerusalem (Israel) Pennsylvania State Univ., University Park (USA))

1991-04-01

346

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

347

Fractal And Multi-fractal Analysis Of The Hydraulic Property Variations Of Karst Aquifers  

NASA Astrophysics Data System (ADS)

Karst aquifers are very heterogeneous systems with hydraulic property variations acting at several continuous and discrete scales, as a result of the fact that macro- structural elements, such as faults and karst channels, and fractures are intertwined in a complex, and largely unknown, manner. Many experimental studies on karst springs showed that the recession limb of the typical storm hydrograph can be divided into several regions with different decreasing rate, suggesting that the discharge is com- posed of contributions experiencing different travel times. Despite the importance of karst aquifers as a source of fresh water for most Mediterranean countries fostered the attention of scientists and practitioners, the mechanisms controlling runoff production in such a complex subsurface environment need to be further explored. A detailed sur- vey, lasting for one year and conducted by the Museo Tridentino di Scienze Naturali of Trento, represents a unique opportunity to analyze the imprint of hydraulic prop- erty variations on the hydrological signal recorded at the spring of Prese Val, located in the Dolomiti group near Trento. Data include water discharge (Q), temperature (T) and electric conductivity of water (E). Analysis of the data revealed that the power spectrum of E scales as 1/f, with slightly, but significantly, smaller than 1. The scaling nature of the E-signal has been confirmed by rescaled range analysis of the time series. Since the electric conductivity is proportional to the concentration of ions in the spring water, which increases with the residence time, one may conclude that the fractal structure of the E signal is the consequence of a similar structure in the hydraulic property variations. This finding confirms previous results of Kirchner et al. (2000), who reported a similar behavior for chloride concentration in the streamflow of three small Welsh catchments. A more detailed analysis revealed that E and T are both multifractal signals suggesting that transport is controlled by hydraulic property variations interesting several scales of variability. However, the travel time distribution is also shaped by the spatial variability of the dissolution rate and of the rainfall, as well as by the occurrence of rate limited dissolution processes. These phenomena may conspire to hide the imprint of the hydraulic property variations on the observed signal, complicating the inference of the geostatistical model of hydraulic property variations from the E signal. The discharge at Prese Val shows a multiscale power spectrum with convexity directed upward, such that the low frequency, long range, contributions to discharge are characterized by a much smaller slope than the high frequency contri- butions, which are characterized by much shorter travel times. This interpretation is consistent with the overall structure of the karst aquifers which is composed of the intertwined arrangement of macro-structures, such as faults and karstic channels, and small-scale diffused fractures, the latter showing a fractal dimension much smaller than that of the former.

Majone, B.; Bellin, A.; Borsato, A.

348

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

349

Impact of harvesting and site preparation on the physical properties of lower coastal plain forest soils  

SciTech Connect

The impact of intensive forest management practices on soil physical properties was examined by collecting intact, 7.6 cm diameter soil core samples to a depth of 30 cm before harvest, after harvest, and after site preparation in plots established in primary skid trails and areas receiving whole-tree and conventional tree-length harvesting treatments. Site preparation for all plots was shear, burn, chop, and bed. Harvesting increased bulk density and decreased aeration porosity in all samples areas. Significant changes in these properties were detected to the 30-cm depth in the skid trail plots. However, significant changes in the whole-tree and tree-length plots were limited to the upper 15 cm of soil. Harvesting also significantly decreased saturated hydraulic conductivity to a depth of 8 cm in the skid trail plots and 15 cm in the tree-length plots but had no significant effect in the whole-tree plots. Bedding proved to be effective in offsetting soil compaction in the whole-tree and tree-length plots by forming a new soil surface, 19 cm in height, over the surface which was trafficed during harvest. Bedding may not be as effective in the skid trail plots because the soil found at the original surface under the bed was compacted to the extent that root growth may be inhibited.

Gent, J.A. Jr.; Ballard, R.; Hassan, A.E.

1983-01-01

350

Influence of Soil Chemical Properties on Adsorption and Oxidation of Phenolic Acids in Soil Suspension  

Microsoft Academic Search

Relationships between abiotic oxidation and adsorption of phenolic acids added to soils and soil chemical properties were investigated by using 32 soil samples and ferulic, vanillic, and p-hydroxybenzoic acids. Soil properties studied were as follows: (as adsorption factors) contents of acid oxalate extractable Al (Alo), Fe (Feo), dithionite-citrate-bicarbonate (DCB) extractable Fe (Fed), total carbon and clay, and (as oxidation factors)

Tomoyuki Makino; Yoshiaki Takahashi; Yasuhiro Sakurai; Masami Nanzyo

1996-01-01

351

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

352

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

Microsoft Academic Search

The authors undertook the task of determining whether base flow alkalinity of surface waters in the northeastern United States is related to indices of soil contact time and flow path partitioning that are derived from topographic and soils information. The influence of topography and soils on catchment hydrology has been incorporated previously in the variable source area model TOPMODEL as

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

1989-01-01

353

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

354

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

355

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

356

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

NASA Astrophysics Data System (ADS)

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

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

2003-12-01

357

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

NASA Astrophysics Data System (ADS)

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

Cappa, F.; Guglielmi, Y.

2010-12-01

358

Artificial neural networks for predicting unsaturated soil hydraulic characteristics at different applied tensions  

Microsoft Academic Search

Direct measurement of unsaturated hydraulic parameters that are crucial inputs in any modeling of water flow or solute transport through the vadose zone is costly and time-consuming. Therefore, indirect methods like artificial neural networks (ANNs) can be used to estimate these parameters. Different ANNs conditions [two training algorithms (Trainlm and Traingd), two transfer functions (Tansig and Logsig), and different combinations

Ali Akbar Moosavi; Ali Sepaskhah

2011-01-01

359

Artificial neural networks for predicting unsaturated soil hydraulic characteristics at different applied tensions  

Microsoft Academic Search

Direct measurement of unsaturated hydraulic parameters that are crucial inputs in any modeling of water flow or solute transport through the vadose zone is costly and time-consuming. Therefore, indirect methods like artificial neural networks (ANNs) can be used to estimate these parameters. Different ANNs conditions [two training algorithms (Trainlm and Traingd), two transfer functions (Tansig and Logsig), and different combinations

Ali Akbar Moosavi; Ali Sepaskhah

2012-01-01

360

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

PubMed Central

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

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

2003-01-01

361

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

SciTech Connect

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

Sklarew, D.S.

1985-05-01

362

Studying soil properties using visible and near infrared spectral analysis  

Microsoft Academic Search

This research is carried out inside the DIGISOIL Project, whose purposes are the integration and improvement of in situ and proximal measurement technologies, for the assessment of soil properties and soil degradation indicators, going form the sensing technologies to their integration and their application in digital soil mapping. The study area is located in the Virginio river basin, about 30

S. Moretti; F. Garfagnoli; L. Innocenti; L. Chiarantini

2009-01-01

363

Greywater reuse for irrigation: effect on soil properties.  

PubMed

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

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

2010-05-15

364

Physicochemical Properties of Soil from Five Villages in Botswana with Respect to Soil Degradation  

Microsoft Academic Search

A field study was conducted at five villages of Botswana namely, Tsabong, Tshane, Mathathane, Motlhabaneng and Tsetsejwe during the periods of June to August 1999 and June to August 2000. The objective of the study was to assess and compare the soil physicochemical properties of soils at the five villages and to study the effect of cultivation on some soil

F. Pule-Meulenberg; B. Moganane

2005-01-01

365

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

366

Properties of Stabilized Peat by Soil-Cement Column Method  

Microsoft Academic Search

A field model study has been carried out to stabilise peat soil using various types of binder by deep mixing method and to investigate its effect on engineering properties. Some soil-cement model columns have been constructed at site and different mechanical properties of stabilised peat, like undrained shear strength, unconfined compressive strength and shear strength was determined after 14 days

Roslan Hashim; Shahidul Islam

367

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

NASA Astrophysics Data System (ADS)

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

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

368

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

USGS Publications Warehouse

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

Schaap, Bryan D.

2000-01-01

369

Hydrologic characterization of desert soils with varying degrees of pedogenesis: 2. Inverse modeling for eff ective properties  

USGS Publications Warehouse

To understand their relation to pedogenic development, soil hydraulic properties in the Mojave Desert were investi- gated for three deposit types: (i) recently deposited sediments in an active wash, (ii) a soil of early Holocene age, and (iii) a highly developed soil of late Pleistocene age. Eff ective parameter values were estimated for a simplifi ed model based on Richards' equation using a fl ow simulator (VS2D), an inverse algorithm (UCODE-2005), and matric pressure and water content data from three ponded infi ltration experiments. The inverse problem framework was designed to account for the eff ects of subsurface lateral spreading of infi ltrated water. Although none of the inverse problems converged on a unique, best-fi t parameter set, a minimum standard error of regression was reached for each deposit type. Parameter sets from the numerous inversions that reached the minimum error were used to develop probability distribu tions for each parameter and deposit type. Electrical resistance imaging obtained for two of the three infi ltration experiments was used to independently test fl ow model performance. Simulations for the active wash and Holocene soil successfully depicted the lateral and vertical fl uxes. Simulations of the more pedogenically developed Pleistocene soil did not adequately replicate the observed fl ow processes, which would require a more complex conceptual model to include smaller scale heterogeneities. The inverse-modeling results, however, indicate that with increasing age, the steep slope of the soil water retention curve shitis toward more negative matric pressures. Assigning eff ective soil hydraulic properties based on soil age provides a promising framework for future development of regional-scale models of soil moisture dynamics in arid environments for land-management applications. ?? Soil Science Society of America.

Mirus, B. B.; Perkins, K. S.; Nimmo, J. R.; Singha, K.

2009-01-01

370

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

PubMed Central

Mesophyll conductance (g m) has been shown to impose significant limitations to net CO2 assimilation (A) in various species during water stress. Net CO2 assimilation is also limited by stomatal conductance to water (g sw), both having been shown to co-vary with leaf hydraulic conductance (K leaf). Lately, several studies have suggested a close functional link between K leaf, g sw, and g m. However, such relationships could only be circumstantial since a recent study has shown that the response of g m to drought could merely be an artefactual consequence of a reduced intercellular CO2 mole fraction (C i). Experiments were conducted on 8-week-old hybrid poplar cuttings to determine the relationship between K leaf, g sw, and g m in clones of contrasting drought tolerance. It was hypothesized that changes in g sw and K leaf in response to drought would not impact on g m over most of its range. The results show that K leaf decreased in concert with g sw as drought procee