Determination Of Hydraulic Conductivity Research Articles

New automatic minidisk infiltrometer: design and testing

Abstract Soil hydraulic conductivity is a key parameter to predict water flow through the soil profile. We have developed an automatic minidisk infiltrometer (AMI) to enable easy measurement of unsaturated hydraulic conductivity using the tension infiltrometer method in the field. AMI senses the cumulative infiltration by recording change in buoyancy force acting on a vertical solid bar fixed in the reservoir tube of the infiltrometer. Performance of the instrument was tested in the laboratory and in two contrasting catchments at three sites with different land use. Hydraulic conductivities determined using AMI were compared with earlier manually taken readings. The results of laboratory testing demonstrated high accuracy and robustness of the AMI measurement. Field testing of AMI proved the suitability of the instrument for use in the determination of sorptivity and near saturated hydraulic conductivity

Back-analysis approach for the determination of hydraulic conductivity in rock caverns

Water seepage related problem is often the major geological hazard in underground rock excavation. In order to reduce the risk associated with extensive seepage, a reliable hydro-geological model should be established based on the in-situ investigation data. One of the challenges for establishing a reliable hydro-geological model is on how to determine the hydraulic conductivities of the fractured rock masses using the limited in-situ investigation data. In this study, a back-analysis approach for the determination of the hydraulic conductivities along a rock cavern is presented. To take the advantages of both the analytical solutions and the numerical methods, this paper proposed a semi-analytical approach for prediction of the water inflow into caverns with the horseshoe section, and the semi-analytical solution is used for the back-analysis of the hydraulic conductivity around a rock cavern based on the in-situ monitoring data. The hydraulic conductivities are obtained by using the EXCEL spreadsheet’s build-in optimization routine SOLVER to minimize the error function. The computed water inflow into the cavern is compared with the in-situ measured data. The results indicate that the derived hydraulic conductivity is acceptable.

Modification of sandy soil hydrophysical environment through bagasse additive under laboratory experiment

Abstract Until now sandy soils can be considered as one roup having common hydrophysical problems. Therefore, a laboratory experiment was conducted to evaluate the influence of bagasse as an amendment to improve hydrophysical properties of sandy soil, through the determination of bulk density, aggregatesize distribution, total porosity, hydraulic conductivity, pore-space structure and water retention. To fulfil this objective, sandy soils were amended with bagasse at the rate of 0, 0.5, 1, 2, 3 and 4% on the dry weight basis. The study results demonstrated that the addition of bagasse to sandy soils in between 3 to 4% on the dry weight basis led to a significant decrease in bulk density, hydraulic conductivity, and rapid-drainable pores, and increase in the total porosity, water-holding pores, fine capillary pores, water retained at field capacity, wilting point, and soil available water as compared with the control treatment

Influence of Soil Cracking on the Soil-Water Characteristic Curve of Clay Soil

The hydraulic conductivity for unsaturated soil conditions is more difficult to estimate than for the saturated condition. In addition, as the soil transitions from intact to cracked, the difficulty in estimating the unsaturated hydraulic conductivity increases. One critical step in the determination of unsaturated flow hydraulic conductivity is the evaluation of the Soil-Water Characteristic Curve (SWCC). In this paper, a series of laboratory studies of direct measurements of cracked soil SWCCs is presented, including challenges associated with the control of very low suction levels associated with crack dewatering. An oedometer-type SWCC apparatus, capable of suction and net normal stress control, and volume change measurement, was used in these experimental studies. It is common that SWCCs are comprised of matric suction values below about 1500 kPa, and total suction values for suctions higher than about 1500 kPa (Fredlund et al., 2012). In this study, all measured or controlled suction values were less than 1500 kPa and obtained using the axis translation method, and the curve in the higher suction range was projected by forcing the SWCC through 106 kPa for completely dried conditions (Fredlund et al., 2012). Volume change corrections were made to the reported volumetric water contents, which is of particular importance when the soil under consideration undergoes volume change in response to wetting or drying. A technique for the determination of the SWCC for cracked clay soils is presented. Test results validated the fact that the SWCC of a cracked soil can be represented by a bimodal function due to the Air Entry Value (AEV) of the cracks being much lower than the AEV of the soil matrix. It was also found that differences between the SWCC for cracked and intact soil appears only in the very low suction range.

Modified SCS-CN and Green-Ampt Methods in Surface Runoff Modelling for the Kundahpallam Watershed, Nilgiris, Western Ghats, India

Kundapallam watershed is located in Nilgiris District of south India. This ungauged watershed has an areal extension of 14.37 km2. There are increasing numbers of rainfall induced landslide occurrences in this area. The causes of rainfall induced landslides require a thorough understanding of runoff characteristics of the watershed. In this respect, the runoff of the study area is estimated with two approaches such as modified Soil Conservation Curve Number (SCS-CN) and Green-Ampt loss method. By these approaches, the related thematic factors on runoff characteristics are prepared with satellite images by using ARCGIS and IDRISI image processing software. The catchment delineation is generated for the Kundapallam watershed to get watershed parameters by using HEC-GeoHMS extension in ARCGIS. Curve number is assigned based on Soil Wetness Index (SWI). Sixteen soil samples were collected from different localities for the determination of hydraulic conductivity, moisture content, wetting front capillary pressure, bulk density, porosity etc. The infiltration rate of sample locations is determined by using double ring infiltrometer. Then all the parameters are assigned to models applied in this study to determine runoff characteristics of the study area. The accuracy and goodness of fit of the model are tested by determining the correlation coefficient (SCS-CN = 0.979 and Green-Ampt = 0.985) and coefficient determination (SCS-CN = 0.958 and Green-Ampt = 0.97) and it indicates statically positive correlations and perfect fit between the results of the study. The results showed that the modified SCS-CN provides low runoff estimation compared than Green-Ampt loss method.

Prediction of Hydraulic Conductivity of Soil Bentonite Mixture Using Hybrid-ANN Approach

Due to its low hydraulic conductivity compacted soil-bentonite mixture is widely used as a barrier material at waste disposal site. The experimental determination of hydraulic conductivity of soil-bentonite mixture, which depends on the various physical and chemical and mineralogical factors, requires expensive and time consuming setup. Thus, a hybrid neural network model (combining genetic algorithm with neural network) is presented here as a complementary tool to model hydraulic conductivity of soil-bentonite mixture. The prediction capability of the model has been found to be satisfactory. The developed model yielded correlation coefficients of 0.98 and 0.97 for training and testing data sets, respectively. The proposed model was compared with conventional neural network models by using different statistical indicators such as Nash-Sutcliffe model efficiency and discrepancy ratio with standard deviation. It was found that the predictions obtained from developed model agreed well with experimental observations. Identification of important parameters and ranking their order of influence on hydraulic conductivity has been discussed by using input significance test.

Determination of hydraulic conductivity of fractured rock masses: A case study for a rock cavern project in Singapore

In order to reduce the risk associated with water seepage in an underground rock cavern project in Singapore, a reliable hydro-geological model should be established based on the in situ investigation data. The key challenging issue in the hydro-geological model building is how to integrate limited geological and hydro-geological data to determine the hydraulic conductivity of the fractured rock masses. Based on the data obtained from different stages (feasibility investigation stage, construction stage, and post-construction stage), suitable models and methods are proposed to determine the hydraulic conductivities at different locations and depths, which will be used at other locations in the future.

Hydraulic conductivity in response to exchangeable sodium percentage and solution salt concentration

Hydraulic conductivity is determined in laboratory assays to estimate the flow of water in saturated soils. However, the results of this analysis, when using distilled or deionized water, may not correspond to field conditions in soils with high concentrations of soluble salts. This study therefore set out to determine the hydraulic conductivity in laboratory conditions using solutions of different electrical conductivities in six soils representative of the State of Pernambuco, with the exchangeable sodium percentage adjusted in the range of 5-30%. The results showed an increase in hydraulic conductivity with both decreasing exchangeable sodium percentage and increasing electrical conductivity in the solution. The response to the treatments was more pronounced in soils with higher proportion of more active clays. Determination of hydraulic conductivity in laboratory is routinely performed with deionized or distilled water. However, in salt affected soils, these determinations should be carried out using solutions of electrical conductivity different from 0 dS m-1, with values close to those determined in the saturation extracts.

Discussion of papers: determination of hydraulic conductivity from grain-size distribution for different depositional environments.

Discussion of papers: determination of hydraulic conductivity from grain-size distribution for different depositional environments.

"Determination of hydraulic conductivity from grain-size distribution for different depositional environments,": authors’ reply.

"Determination of hydraulic conductivity from grain-size distribution for different depositional environments,": authors’ reply.

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

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.

Book Review: “Hydraulic Conductivity—Issues, Determination and Applications”, L. Elango (ed.), InTech, Croatia

Hydraulic conductivity is probably the most important hydrogeological parameter, as it governs, along with other parameters, the flow of fluids and migration of contaminants beneath the ground surface, especially in soils and aquifers. There are already many books on broad aspects of hydrogeology and groundwater hydraulics that briefly review the determination of hydraulic conductivity. However, over the past several decades, due to the rapid development of science and technology and the ever-increasing groundwater extraction and contamination, many new theories, methodologies and applications regarding hydraulic conductivity have emerged. As a result, a book is needed to provide a useful collection of the current state of knowledge on the topic. Hydraulic Conductivity—Issues, Determination and Applications, edited by L. Elango (ISBN 978-953-307-288-3, 446p.) was recently published by InTech, an open access publisher based in Croatia (Elango 2011). Just 7 months before the publication of this book, another book entitled “Developments in Hydraulic Conductivity Research”, edited by Oagile Dikinya (2011), was published by the same publisher. Both these books report the latest advances of research within the hydraulic conductivity field of study and are worth reading, but the book by Elango (2011) is more extensive in content and has a more applied focus than the former one. It was published as open access, which enables everyone interested in this topic to read it free of charge, benefitting readers, authors, as well as science in general. Contributing authors come from around the world including Turkey, India, Brazil, Nigeria, Poland, Spain, USA, Iran, Germany, Canada, Mexico, Taiwan, Italy, France, Bolivia, Thailand and Australia. This book is organized into five clustered themes, and comprises a total of 21 chapters. A reference list is appended at the end of each chapter, which includes several recent references that allow readers to gain further information on specific topics. However, a shortcoming is the lack of an abstract for each chapter, thus readers are unable to get a quick glance at the main findings of each chapter. Environ. Process. (2014) 1:613–616 DOI 10.1007/s40710-014-0033-7

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

• A new solution for steady-state evaporation from coarse-textured porous media is presented. • The solution is not restricted to a specific form of the unsaturated hydraulic conductivity function. • The solution offers an alternative method for determination of unsaturated hydraulic conductivity. • Based on this theory, “effective” hydraulic properties of layered soils can be estimated. 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.

Experimental measurement on the hydraulic conductivity of deep low-permeability rock

Hydraulic conductivity is an important hydrogeological parameter and is difficultly measured by laboratory experiments. In order to obtain the effective hydraulic conductivity of deep low-permeability rock and to study the water flow behavior within the rocks, in situ water injection experiments were employed in a deep underground tunnel. The applicability of Darcy’s law is discussed as well. The study results show that Darcy’s law may still be applicable for the initial determination of hydraulic conductivity for a partial transitional flow of water injection experiments, which retains linear relationship between pressure and flow rate. Water flow behavior in the rock experiences the initial stable phase, the increase phase, and the late stable phase in general but also has distinct flow properties due to the different characters of rocks. Hydraulic conductivity change with differential injection pressure can be divided into two phases, i.e., approximated constant hydraulic conductivity values which can be considered as the hydraulic conductivity of the rock in the initial flow phase and its effective value jump in the flow mutation phase caused by hydraulic fracturing.

Registros de alta resolución de la conductividad hidráulica saturada en testigos de perforaciones usando mediciones de permeabilidad al aire

Saturated hydraulic conductivity (K s) is one of the most important parameters determining groundwater flow and contaminant transport in both unsaturated and saturated porous media. The hand-held air permeameter technique was investigated for high-resolution hydraulic conductivity determination on borehole cores using a spatial resolution of ∼0.05 m. The suitability of such air permeameter measurements on friable to poorly indurated sediments was tested to improve the spatial prediction of classical laboratory-based K s measurements obtained at a much lower spatial resolution (∼2 m). In total, 368 K s measurements were made on ∼350 m of borehole cores originating from the Campine basin, northern Belgium, while ∼5,230 air permeability measurements were performed on the same cores, resulting in a K s range of seven orders of magnitude. Cross-validation demonstrated that, using air permeameter data as the secondary variable for laboratory based K s measurements, the performance increased from R 2 = 0.35 for ordinary kriging (laboratory K s only) to R 2 = 0.61 for co-kriging. The separate treatment of horizontal and vertical hydraulic conductivity revealed considerable anisotropy in certain lithostratigraphical units, while others were clearly isotropic at the sample scale. Air permeameter measurements on borehole cores provide a cost-effective way to improve spatial predictions of traditional laboratory based K s.

Effect of mouldboard ploughing and shallow tillage on sub-soil physical properties and crop performance

This study was conducted in spring 2011 in a long-term field experiment with the objective of assessing the effect of shallow tillage (ST) and mouldboard ploughing (MP) on important soil physical properties and crop performance. Undisturbed soil samples were taken before sowing from depths of 15–20, 25–30 and 35–40 cm for the determination of saturated hydraulic conductivity (Ks), bulk density (Bd), and water retention capacity in laboratory conditions. Penetrometer resistance (PR) was measured in the field after 1 month of sowing. Plant density of barley (Hordeum vulgare) was also counted after 1 month of sowing. Field water content was significantly higher for MP than ST at 15–20 cm (MP = 27%, ST = 22.5%) and 25–30 cm depth (MP = 29.3%, ST = 24.8). Water retention at 1 m suction was also significantly higher in the treatment with MP at the depth of 25–30 cm (31%) than in the ST treatment (27.7%). Significantly higher Ks value was found for ST at depths of 15–20 (13.09 cm h−1) and 25–30 cm (5.10 cm h−1) than for MP (11.15 and 3.52 cm h−1, respectively). Soil Bd was significantly lower in MP treatments for the first two investigated depths (1.43 and 1.44 g cm−3, respectively) than in the ST (1.54 and 1.53 g cm−3). Significant higher PR value was found for ST, especially at the depth of 5–35 cm, but the result was not so high as to reduce the root growth. Water content determined parallel with PR measurement was not significantly different for the two treatments. Plant density as well as crop yield in the ST treatment was higher (3840 kg ha−1) than in the MP treatment (2490 kg ha−1). Therefore, we concluded that long-term ST treatment markedly influenced crop performance and yield by facilitating soil physical properties.

Water Uptake along the Length of Grapevine Fine Roots: Developmental Anatomy, Tissue-Specific Aquaporin Expression, and Pathways of Water Transport

To better understand water uptake patterns in root systems of woody perennial crops, we detailed the developmental anatomy and hydraulic physiology along the length of grapevine (Vitis berlandieri × Vitis rupestris) fine roots from the tip to secondary growth zones. Our characterization included the localization of suberized structures and aquaporin gene expression and the determination of hydraulic conductivity (Lpr) and aquaporin protein activity (via chemical inhibition) in different root zones under both osmotic and hydrostatic pressure gradients. Tissue-specific messenger RNA levels of the plasma membrane aquaporin isogenes (VvPIPs) were quantified using laser-capture microdissection and quantitative polymerase chain reaction. Our results highlight dramatic changes in structure and function along the length of grapevine fine roots. Although the root tip lacked suberization altogether, a suberized exodermis and endodermis developed in the maturation zone, which gave way to the secondary growth zone containing a multilayer suberized periderm. Longitudinally, VvPIP isogenes exhibited strong peaks of expression in the root tip that decreased precipitously along the root length in a pattern similar to Arabidopsis (Arabidopsis thaliana) roots. In the radial orientation, expression was always greatest in interior tissues (i.e. stele, endodermis, and/or vascular tissues) for all root zones. High Lpr and aquaporin protein activity were associated with peak VvPIP expression levels in the root tip. This suggests that aquaporins play a limited role in controlling water uptake in secondary growth zones, which contradicts existing theoretical predictions. Despite having significantly lower Lpr, woody roots can constitute the vast majority of the root system surface area in mature vines and thus provide for significant water uptake potential.

A study on unsaturated hydraulic conductivity of hill soil of north-east India

Hill slope hydrology in terms of surface drainage and infiltration is important for analysing its stability and understanding the possibility of landslides. The infiltrating water during rainfall is found to cause instability to the slope. The location of water table will be low in such hill slopes and the soil will be mostly unsaturated. Therefore, the subsurface drainage of infiltrating water in a slope is influenced by the unsaturated hydraulic conductivity (ku ) of soil. The hill slopes of north-east India mainly constitute unsaturated red soil. There are not many studies related to the determination of unsaturated hydraulic conductivity of this soil. Direct experimental determination of ku is a challenging task and requires costly and skilled experimentation. Therefore, the normal practice is to obtain ku based on water retention characteristic (WRC) and saturated hydraulic conductivity (ks ) of the soil. In this study, an equitensiometer, a matric potential sensor and a relative humidity sensor have been used to measure WRCs of hilly red soil. The study indicates that the measurement methodologies have significant influence on the uniqueness of WRC of red soil and, hence, the estimation of ku .

Determination of vertical hydraulic conductivity of aquitards in a multilayered leaky system using water-level signals in adjacent aquifers

Summary This paper presents a methodology for determining the vertical hydraulic conductivity ( K v ) of an aquitard, in a multilayered leaky system, based on the harmonic analysis of arbitrary water-level fluctuations in aquifers. As a result, K v of the aquitard is expressed as a function of the phase-shift of water-level signals measured in the two adjacent aquifers. Based on this expression, we propose a robust method to calculate K v by employing linear regression analysis of logarithm transformed frequencies and phases. The frequencies, where the K v is calculated, are identified by coherence analysis. The proposed methods are validated by a synthetic case study and are then applied to the Westbourne and Birkhead aquitards, which form part of a five-layered leaky system in the Eromanga Basin, Australia.

Determination of saturated and unsaturated hydraulic conductivity using diviner 2000 capacitance probe

The estimation of hydraulic conductivity indicates how fluids flow through a substance and thus determine the water balance in the soil profile. In determining the saturated and unsaturated hydraulic conductivity of soil, five plots of 5.0 x 4.0 m were prepared with a PVC access tube installed in each plot. The plots were ponded profusely and surface covered with grass to prevent water loss by evaporation or water input by rain. The readings were taken twice daily for over a period of 5 days using capacitance probe with trade name Diviner 2000. The Diviner 2000 uses the method that utilizes the high dielectric constant of water compare to soil and air to determine water content of the soil. The trend lines of hydraulic conductivity has its linear regression r = 0.8296 - 0.9273 and its saturated hydraulic conductivity in the range of 5.09 cmh-1 – 14.03cmh-1 and unsaturated hydraulic conductivity in the range of 0.700 cmh-1 – 0.785 cmh-1. This reveals that soil water content can be obtained reasonably well from a capacitance probe which will allow for a determination of the pattern and use of the referred soil.