Rapid and precise measurement of infiltration in situ is important for characterizing soil proper... more Rapid and precise measurement of infiltration in situ is important for characterizing soil properties. We describe an automated, selfregulating, single-ring infiltrometer useful for measuring infiltration rates between 1 x 10~8 and 3.7 x 10--' m s~'. The infiltrometer limits to ± 1 mm fluctuations in the height of water ponded in a containment ring. Flow rates are calculated from changes in water height in a Mariotte reservoir with time. Water height changes are measured as the difference in pressure between two pressure transducers, one at the top of the Mariotte reservoir and one at the base.
Soil hydraulic properties are quite variable, and characterization of field sites usually require... more Soil hydraulic properties are quite variable, and characterization of field sites usually requires many measurements. One way to collect the data needed for field site characterization is to use multiple infiltrometers with automated data collection capabilities. Automated infiltrometers use pressure transducers connected to a dataiogger to measure cumulative infiltration over time. The FLOWDATA soRware was developed to reformat, graphically display, and analyze the large well-structured data sets collected with automated infiltrometers. Program features include interactive editing, graphing, statistical summaries for each infiltration data set, and pooling of estimates from multiple data sets. Inputs required are identification codes, times, transducer voltage readings, and transducer calibration files. Outputs are infiltration rates, and saturated and unsaturated hydraulic conductivities. Program performance is demonstrated with data from a typical field data file.
The Ruby Gulch repository at the Gilt Edge Mine Superfund site is a capped waste rock repository.... more The Ruby Gulch repository at the Gilt Edge Mine Superfund site is a capped waste rock repository. Early in the system design EPA and its subcontractor, Bureau of Reclamation, recognized the need for long-term monitoring system to provide information on the repository behavior with the following objectives: 1 Provide information on the integrity of the newly constructed surface cover and diversion system 2 Continually assess the waste's hydrological and geochemical behavior, such that rational decisions can be made for the operation of this cover and liner system 3 Easily access of information pertaining to the system performance to stakeholders 4 Integration of a variety of data sources to produce information which could be used to enhance future cover designs. Through discussions between EPA, the Bureau of Reclamation and Idaho National Laboratory a long-term monitoring system was designed and implemented allowing EPA to meet these objectives. This system was designed to provide a cost effective way to deal with massive amounts of data and information, subject to the following specifications: 1 Data acquisition should occur autonomously and automatically, 2 Data management, processing and presentation should be automated as much as possible, 3 Users should be able to access all data and information remotely through a web browser. The INL long-term monitoring system integrates the data from a set of 522 electrodes resistivity electrodes consisting of 462 surface electrodes and 60 borehole electrodes (in 4 wells with 15 electrodes each), an outflow meter at the toe of the repository, an autonomous, remotely accessible weather station, and four wells (average depths of 250 feet) with thermocouples, pressure transducers and sampling ports for water and air. The monitoring system has currently been in operation for over a year, and has collected data continuously over this period. Results from this system have shown both the diurnal variation in rockmass behavior, movement of water through the waste (allowing estimated in residence time) and are leading to a comprehensive model of the repository behavior. Due to the sheer volume of data, a user driven interface allows users to create their own views of the different datasets.
Spatial variability of surface hydraulic properties and the extrinsic (e.g., traffic, cropping, e... more Spatial variability of surface hydraulic properties and the extrinsic (e.g., traffic, cropping, etc.) and intrinsic (e.g., soil type, pore size distribution, etc.) factors associated with these properties are important for infiltration and runoff processes in agricultural fields. Disc infiltrometers measured infiltration at 296 sites arranged on two parallel transects. To examine and differentiate the factors contributing to spatial structure under different field conditions these measurements were made in the corn rows, no-track interrows, and wheel track interrows of the field using four different soil water tensions * (0, 30, 60, and 150 mm). Unsaturated hydraulic conductivity (K) and saturated hydraulic conductivity (K,) were maximum in the corn rows and minimum in wheel track inter-rows, with no-track interrows intermediate. Exponents (CZ parameters) of K, and K relationships (K = K, exp -aV) for corn rows and no-track interrows were not significantly different from each other but were significantly different from Q for the wheel track interrows at P = 0.01 level. Spatial variability of K and K, values showed some pseudoproportional effect in nugget variance for all three field conditions. No-track interrows clearly showed an inverse trend for semivariogram of K with changing tension (q) values, whereas differences were found for corn rows and wheel traffic interrows. The spatial structure of (Y for all three field conditions were mostly white noise. Under corn rows, in addition to random variation, a small five-row periodic variation at the P = 0.20 level, matching the five-row traffic configuration, was discovered. The spatial structure of a was influenced by soil type for the no-track interrows. Spatial structure was absent in wheel track interrows, indicating the destruction of pore structure due to compaction. and Luxmoore, 1986; Wilson and Luxmoore, 1988] revealed that more than 70% of water flux can move through the macropores. Meek et al. [ 1989] found 2 to 3 times increase in the infiltration rates over a 3-year period for a field under flood irrigation practice planted to alfalfa. The authors attributed the increase to flow through root channels. Shirmohammadi and Skaggs [1984] conducted experiments to determine the effects of different factors including plant cover on infiltration into columns of fine sand. They found that fescue roots loosened the soil and increased the hydraulic conductivity by an average of 40% over soybeans and 80% over bare soil. Surface soil conditions, resulting from different tillage practices and/or wheel traffic compaction, likely will contribute to spatial variation of the soil macroporosity, thereby altering the hydraulic properties. Disregarding these factors may confound the interpretation of infiltration and runoff results.
ph: (865) 576-8401 fax: (865) 576-5728 email: reports@adonis.osti.gov Available to the public fro... more ph: (865) 576-8401 fax: (865) 576-5728 email: reports@adonis.osti.gov Available to the public from the National Technical Information Service, U.S. Department of Commerce, 5285 Port Royal Rd., Springfield, VA 22161 ph: (800) 553-6847 fax: (703) 605-6900 email: orders@ntis.fedworld.gov online ordering: http://www.ntis.gov/ordering.htm
Information on subsurface processes is required for a broad range of applications, including site... more Information on subsurface processes is required for a broad range of applications, including site remediation, groundwater management, fossil fuel production and CO2 sequestration. Data on these processes is obtained from diverse sensor networks, includes physical, hydrological and chemical sensors and semi permanent geophysical sensors (mainly seismic and resistivity). Currently, processing is done by specialists through the use of commercial and research software packages such as numerical inverse and forward models, statistical data analysis software and visualization and data presentation packages. Information is presented to stakeholders as tables, images and reports. Processing steps, data and assumptions used for information generation are mostly opaque to endusers. As data migrates between applications the steps taken in each application (e.g. in data reduction)are often only partly documented, resulting in irreproducible results. In this approach, interactive tuning of data processing in a systematic way (e.g. changing model parameters, visualization parameters or data used) or using data processing as a discovery tool is de facto impossible. We implemented a web accessible scientific workflow system for subsurface performance monitoring. This system integrates distributed, automated data acquisition from autonomous sensor networks with server side data management and information visualization through flexible browser based data access tools. Webservices are used for communication with the sensor networks and interaction with applications. This system was originally developed for a monitoring network at the Gilt Edge Mine Superfund site, but has now been implemented for a range of different sensor networks of different complexity. The workflow framework allows for rapid and easy integration in a modular, transparent and reproducible manner of a multitude of existing applications for data analysis and processes. By embedding applications in webservice wrappers existing applications can be used without any recoding. Webservices are used for application configuration, resource allocation and communication of data and parameters. We implemented both the statistical package R as well as geophysical inverse codes and hydrological forward models as webservices. This framework and implementation allows for reproducible, transparent result generation by a diverse user base through an easy to use web interface. The use of webservices allows this system to integrate seamlessly with current and future efforts in distributed computing.
An automated tension infiltrometer useful for a range of water tensions from 0.02 to 0.50 m and f... more An automated tension infiltrometer useful for a range of water tensions from 0.02 to 0.50 m and for infiltration rates of 1 x 10 8 to 5 x 1(H m s ' is described. Infiltration rates are calculated from the change in water height in a Mariotte column. Water height is automatically measured by using the difference in tension between two pressure transducers, one installed at the top, and the other at the bottom, of the Mariotte column. Precision of water height measurement using two transducers (SD = 2.2 mm) is increased as compared with height measurements made with only one transducer (SD = 6.2 mm). With only one transducer, much of the measurement error is due to tension fluctuations or "noise" caused by bubbling in the Mariotte column. The new design also incorporates several features used or suggested by other workers. A bubble tower is used for tension regulation, and interchangeable Mariotte columns of different diameters are used to match column volume with expected cumulative infiltration. Advantages of the new device include (i) quick and accurate tension control at low tensions, (ii) improved measurement precision at low flow rates, and (iii) automatic measurement and data collection, which increases measurement speed and eliminates bubbling-induced variability.
Spatial variability of surface hydraulic properties and the extrinsic (e.g., traffic, cropping, e... more Spatial variability of surface hydraulic properties and the extrinsic (e.g., traffic, cropping, etc.) and intrinsic (e.g., soil type, pore size distribution, etc.) factors associated with these properties are important for infiltration and runoff processes in agricultural fields. Disc infiltrometers measured infiltration at 296 sites arranged on two parallel transects. To examine and differentiate the factors contributing to spatial structure under different field conditions these measurements were made in the corn rows, no-track interrows, and wheel track interrows of the field using four different soil water tensions * (0, 30, 60, and 150 mm). Unsaturated hydraulic conductivity (K) and saturated hydraulic conductivity (K,) were maximum in the corn rows and minimum in wheel track inter-rows, with no-track interrows intermediate. Exponents (CZ parameters) of K, and K relationships (K = K, exp -aV) for corn rows and no-track interrows were not significantly different from each other but were significantly different from Q for the wheel track interrows at P = 0.01 level. Spatial variability of K and K, values showed some pseudoproportional effect in nugget variance for all three field conditions. No-track interrows clearly showed an inverse trend for semivariogram of K with changing tension (q) values, whereas differences were found for corn rows and wheel traffic interrows. The spatial structure of (Y for all three field conditions were mostly white noise. Under corn rows, in addition to random variation, a small five-row periodic variation at the P = 0.20 level, matching the five-row traffic configuration, was discovered. The spatial structure of a was influenced by soil type for the no-track interrows. Spatial structure was absent in wheel track interrows, indicating the destruction of pore structure due to compaction. and Luxmoore, 1986; Wilson and Luxmoore, 1988] revealed that more than 70% of water flux can move through the macropores. Meek et al. [ 1989] found 2 to 3 times increase in the infiltration rates over a 3-year period for a field under flood irrigation practice planted to alfalfa. The authors attributed the increase to flow through root channels. Shirmohammadi and Skaggs [1984] conducted experiments to determine the effects of different factors including plant cover on infiltration into columns of fine sand. They found that fescue roots loosened the soil and increased the hydraulic conductivity by an average of 40% over soybeans and 80% over bare soil. Surface soil conditions, resulting from different tillage practices and/or wheel traffic compaction, likely will contribute to spatial variation of the soil macroporosity, thereby altering the hydraulic properties. Disregarding these factors may confound the interpretation of infiltration and runoff results.
Tillage and wheel-traffic compaction alter pore structure and hydraulic properties of agricultura... more Tillage and wheel-traffic compaction alter pore structure and hydraulic properties of agricultural soils. These alterations will affect root growth and movement of water and solutes. This study was conducted to develop new methods needed to characterize the effects of wheel traffic and tillage on pore structure as measured by water flow through macropores. Unconfined (three-dimensional) saturated and unsaturated infiltration measurements (0-, 30-, 60-, and 150mm water tension) at the soil surface were taken sequentially at field sites to determine the steady-state rate of water flow through different pore-size classes on a Tama silty clay loam (fine-silty, mixed, mesic Typic Argiudoll). A tension infiltrometer was used to obtain the unsaturated infiltration rates. Sites were selected on trafficked and untrafficked interrow positions in two tillage systems (chisel plow and no-till). Steady-state infiltration rates from 2 to 300 ion s" 1 were measured. Increasing the tension of applied water resulted in decreasing infiltration rates for both tillages and traffic treatments because, as tensions increased, larger pores emptied. Wheel traffic reduced infiltration rates in both tillages, but caused a greater decrease in infiltration rates in the chisel-plow system than in no-till. Increasing tension caused proportionately smaller decreases in infiltration rates for wheel-trafficked positions. This suggests that larger macropores were transporting a greater proportion of the total water flow in untrafficked soil than in trafficked soil and reinforces the concept that larger, as opposed to smaller, pores are more easily destroyed by wheel traffic. Unconfined infiltration measurements were shown to be useful in quantifying the effects of tillage and compaction on soil macropores.
Spatial variability of surface hydraulic properties and the extrinsic (e.g., traffic, cropping, e... more Spatial variability of surface hydraulic properties and the extrinsic (e.g., traffic, cropping, etc.) and intrinsic (e.g., soil type, pore size distribution, etc.) factors associated with these properties are important for infiltration and runoff processes in agricultural fields. Disc infiltrometers measured infiltration at 296 sites arranged on two parallel transects. To examine and differentiate the factors contributing to spatial structure under different field conditions these measurements were made in the corn rows, no-track interrows, and wheel track interrows of the field using four different soil water tensions Ψ (0, 30, 60, and 150 mm). Unsaturated hydraulic conductivity (K) and saturated hydraulic conductivity (Ks) were maximum in the corn rows and minimum in wheel track interrows, with no-track interrows intermediate. Exponents (α parameters) of Ks and K relationships (K = Ks exp-αΨ) for corn rows and no-track interrows were not significantly different from each other but were significantly different from a for the wheel track interrows at P = 0.01 level. Spatial variability of K and Ks values showed some pseudoproportional effect in nugget variance for all three field conditions. No-track interrows clearly showed an inverse trend for semivariogram of K with changing tension (Ψ) values, whereas differences were found for corn rows and wheel traffic interrows. The spatial structure of a for all three field conditions were mostly white noise. Under corn rows, in addition to random variation, a small five-row periodic variation at the P = 0.20 level, matching the five-row traffic configuration, was discovered. The spatial structure of α was influenced by soil type for the no-track interrows. Spatial structure was absent in wheel track interrows, indicating the destruction of pore structure due to compaction.
Long-term performance of a waste-containment facility liner system can be simply and inexpensivel... more Long-term performance of a waste-containment facility liner system can be simply and inexpensively monitored in dry climates by relative humidity measurements. An increase in humidity as atmospheric air is circulated through a dry coarse layer within the liner system indicates imminent movement of water into the layer. Continued airflow will evaporate and remove water, thereby restoring the coarse layer to
A new method is proposed for determining in situ unsaturated hydraulic conductivities from unsatu... more A new method is proposed for determining in situ unsaturated hydraulic conductivities from unsaturated infiltration measurements made at several tensions on the same infiltration surface. Wooding's equation for steady-state unconfined infiltration rates is used in calculating hydraulic conductivities. Hydraulic conductivities calculated with the new method are consistent with unit gradient laboratory measurements of saturated and unsaturated hydraulic conductivity. This simple field method is potentially valuable because it is faster than unit gradient laboratory methods, and it is less disruptive of pore continuity than other field infiltration techniques.
Traffic effects on pore structure and hydraulic properties of soils may be affected by site-speci... more Traffic effects on pore structure and hydraulic properties of soils may be affected by site-specific factors. The objective of this study was to determine if the effects of wheel traffic on infiltration rates in chisel-plow and no-till tillage systems differed among five Midwestern locations. Ponded and unsaturated (30-, 60-, and 150-nun water tension head) infiltration rates were measured sequentially using infiltrometers after removing surface residues and the upper 2 cm of soil. Wheel traffic reduced ponded infiltration rates in both tillage systems at all locations, ranging from 95% in the chisel-plow system in Iowa to approximately 55% in the chisel-plow system in Missouri. Tillage systems significantly affected ponded infiltration rates at only two of the locations. At the Minnesota and Nebraska locations, no-till reduced ponded infiltration rates in untrafficked interrows by 33 and 64%, respectively, compared with those in the chisel-plow system. Ponded infiltration rates of trafficked interrows did not differ between tillage systems at any location. At the Iowa and Nebraska locations, the decrease in infiltration rate with an increase in tension head was greater for untrafficked interrows than for trafficked interrows in the chisel-plow system. The large pores that drain at 30 mm of tension head accounted for a lower percentage of the water flow with ponding in trafficked interrows (73%) than in untrafficked interrows (88%). Infiltration rate comparisons between tillage systems should consider wheel traffic patterns.
Effective porosity in solute-transport analyses is usually estimated rather than calculated from... more Effective porosity in solute-transport analyses is usually estimated rather than calculated from tracer tests in the field or laboratory. Calculated values of effective porosity in the laboratory on three different textured samples were compared to estimates derived from particle-size distributions and soil–water characteristic curves. The agreement was poor and it seems that no clear relationships exist between effective porosity calculated from laboratory tracer tests and effective porosity estimated from particle-size distributions and soil–water characteristic curves. A field tracer test in a sand-and-gravel aquifer produced a calculated effective porosity of approximately 0.17. By comparison, estimates of effective porosity from textural data, moisture retention, and published values were approximately 50–90% greater than the field calibrated value. Thus, estimation of effective porosity for chemical transport is highly dependent on the chosen transport model and is best obtained by laboratory or field tracer tests. La porosité effective dans les analyses de transport de soluté est habituellement estimée, plutôt que calculée à partir d'expériences de traçage sur le terrain ou au laboratoire. Les valeurs calculées de la porosité effective au laboratoire sur trois échantillons de textures différentes ont été comparées aux estimations provenant de distributions de taille de particules et de courbes caractéristiques sol-eau. La concordance était plutôt faible et il semble qu'il n'existe aucune relation claire entre la porosité effective calculée à partir des expériences de traçage au laboratoire et la porosité effective estimée à partir des distributions de taille de particules et de courbes caractéristiques sol-eau. Une expérience de traçage de terrain dans un aquifère de sables et de graviers a fourni une porosité effective calculée d'environ 0,17. En comparaison, les estimations de porosité effective de données de texture, de teneur en eau et les valeurs publiées étaient environ 50 à 90% plus fortes que la valeur calibrée sur le terrain. Ainsi, l'estimation de la porosité effective pour le transport en solution dépend fortement du modèle de transport utilisé et est préférable lorsqu'elle est obtenue à partir d'expériences de traçage de laboratoire ou de terrain. La porosidad efectiva en el análisis del transporte de solutos se suele estimar, en lugar de calcularse a partir de ensayos de trazadores en el campo o el laboratorio. Los valores calculados de la porosidad efectiva en el laboratorio en tres muestras de distintas texturas se compararon con las estimaciones realizadas a partir de las distribuciones de tamaño de partículas y de las curvas características suelo-agua. El ajuste fue bastante pobre y parece que no existe una relación clara entre los valores de la porosidad efectiva calculados mediante los tres métodos. Un ensayo de trazadores en el campo, en un acuífero formado por arenas y gravas, dio lugar a un valor de porosidad efectiva calculado de 0.17. Las estimaciones realizadas a partir de los datos de textura, humedad retenida y valores publicados eran entre un 50–90 por ciento mayores que el valor calibrado en el ensayo de campo. Así, la estimación del valor de la porosidad efectiva para el transporte químico depende mucho del modelo de transporte seleccionado y es mejor si se obtiene a partir de ensayos de laboratorio o de campo.
Automated and autonomous monitoring of environmental conditions can be used to improve operationa... more Automated and autonomous monitoring of environmental conditions can be used to improve operational efficiency, verify remedial action decisions, and promote confidence in the monitoring process by making data and associated derived information readily accessible to regulators and stakeholders. Ultimately autonomous monitoring systems can reduce overall costs associated with regulatory compliance of performance and long- term monitoring. As part of a joint decision between DOE and the WA Department of Ecology to put on "cold standby" a pump and treat system that has been operating on the Department of Energy's Hanford site in Washington State since 1995, a web site was developed to display the automated water level network around the pump and treat system. The automated water level network consists of nineteen wells with water level transducers and temperature and conductivity probes for selected wells. Data from this network will be used to evaluate the impacts of the pump-and-treat system and the response of the aquifer to shutdown of the system. The website will provide access to data from the automated network along with additional information pertaining to the shutdown of the pump and treat system to the various stakeholders in a convenient and timely fashion. This will allow the various stakeholders to observe the impacts of the shutdown as the aquifer responds. There are future plans to expand this web-based data reporting platform to other environmental data that pertains to the various remedial actions planned at the Hanford site. The benefits of the web site application for monitoring and stewardship are: consistency of data processing and analyses with automated and on demand data and information delivery. The system and data access is password controlled and access to various data or fields can be restricted to specified users. An important feature is that the stakeholders have access to the data in near-real time providing a checks-and-balance system that can potentially increase confidence in the remedy selection.
Rapid and precise measurement of infiltration in situ is important for characterizing soil proper... more Rapid and precise measurement of infiltration in situ is important for characterizing soil properties. We describe an automated, selfregulating, single-ring infiltrometer useful for measuring infiltration rates between 1 x 10~8 and 3.7 x 10--' m s~'. The infiltrometer limits to ± 1 mm fluctuations in the height of water ponded in a containment ring. Flow rates are calculated from changes in water height in a Mariotte reservoir with time. Water height changes are measured as the difference in pressure between two pressure transducers, one at the top of the Mariotte reservoir and one at the base.
Soil hydraulic properties are quite variable, and characterization of field sites usually require... more Soil hydraulic properties are quite variable, and characterization of field sites usually requires many measurements. One way to collect the data needed for field site characterization is to use multiple infiltrometers with automated data collection capabilities. Automated infiltrometers use pressure transducers connected to a dataiogger to measure cumulative infiltration over time. The FLOWDATA soRware was developed to reformat, graphically display, and analyze the large well-structured data sets collected with automated infiltrometers. Program features include interactive editing, graphing, statistical summaries for each infiltration data set, and pooling of estimates from multiple data sets. Inputs required are identification codes, times, transducer voltage readings, and transducer calibration files. Outputs are infiltration rates, and saturated and unsaturated hydraulic conductivities. Program performance is demonstrated with data from a typical field data file.
The Ruby Gulch repository at the Gilt Edge Mine Superfund site is a capped waste rock repository.... more The Ruby Gulch repository at the Gilt Edge Mine Superfund site is a capped waste rock repository. Early in the system design EPA and its subcontractor, Bureau of Reclamation, recognized the need for long-term monitoring system to provide information on the repository behavior with the following objectives: 1 Provide information on the integrity of the newly constructed surface cover and diversion system 2 Continually assess the waste's hydrological and geochemical behavior, such that rational decisions can be made for the operation of this cover and liner system 3 Easily access of information pertaining to the system performance to stakeholders 4 Integration of a variety of data sources to produce information which could be used to enhance future cover designs. Through discussions between EPA, the Bureau of Reclamation and Idaho National Laboratory a long-term monitoring system was designed and implemented allowing EPA to meet these objectives. This system was designed to provide a cost effective way to deal with massive amounts of data and information, subject to the following specifications: 1 Data acquisition should occur autonomously and automatically, 2 Data management, processing and presentation should be automated as much as possible, 3 Users should be able to access all data and information remotely through a web browser. The INL long-term monitoring system integrates the data from a set of 522 electrodes resistivity electrodes consisting of 462 surface electrodes and 60 borehole electrodes (in 4 wells with 15 electrodes each), an outflow meter at the toe of the repository, an autonomous, remotely accessible weather station, and four wells (average depths of 250 feet) with thermocouples, pressure transducers and sampling ports for water and air. The monitoring system has currently been in operation for over a year, and has collected data continuously over this period. Results from this system have shown both the diurnal variation in rockmass behavior, movement of water through the waste (allowing estimated in residence time) and are leading to a comprehensive model of the repository behavior. Due to the sheer volume of data, a user driven interface allows users to create their own views of the different datasets.
Spatial variability of surface hydraulic properties and the extrinsic (e.g., traffic, cropping, e... more Spatial variability of surface hydraulic properties and the extrinsic (e.g., traffic, cropping, etc.) and intrinsic (e.g., soil type, pore size distribution, etc.) factors associated with these properties are important for infiltration and runoff processes in agricultural fields. Disc infiltrometers measured infiltration at 296 sites arranged on two parallel transects. To examine and differentiate the factors contributing to spatial structure under different field conditions these measurements were made in the corn rows, no-track interrows, and wheel track interrows of the field using four different soil water tensions * (0, 30, 60, and 150 mm). Unsaturated hydraulic conductivity (K) and saturated hydraulic conductivity (K,) were maximum in the corn rows and minimum in wheel track inter-rows, with no-track interrows intermediate. Exponents (CZ parameters) of K, and K relationships (K = K, exp -aV) for corn rows and no-track interrows were not significantly different from each other but were significantly different from Q for the wheel track interrows at P = 0.01 level. Spatial variability of K and K, values showed some pseudoproportional effect in nugget variance for all three field conditions. No-track interrows clearly showed an inverse trend for semivariogram of K with changing tension (q) values, whereas differences were found for corn rows and wheel traffic interrows. The spatial structure of (Y for all three field conditions were mostly white noise. Under corn rows, in addition to random variation, a small five-row periodic variation at the P = 0.20 level, matching the five-row traffic configuration, was discovered. The spatial structure of a was influenced by soil type for the no-track interrows. Spatial structure was absent in wheel track interrows, indicating the destruction of pore structure due to compaction. and Luxmoore, 1986; Wilson and Luxmoore, 1988] revealed that more than 70% of water flux can move through the macropores. Meek et al. [ 1989] found 2 to 3 times increase in the infiltration rates over a 3-year period for a field under flood irrigation practice planted to alfalfa. The authors attributed the increase to flow through root channels. Shirmohammadi and Skaggs [1984] conducted experiments to determine the effects of different factors including plant cover on infiltration into columns of fine sand. They found that fescue roots loosened the soil and increased the hydraulic conductivity by an average of 40% over soybeans and 80% over bare soil. Surface soil conditions, resulting from different tillage practices and/or wheel traffic compaction, likely will contribute to spatial variation of the soil macroporosity, thereby altering the hydraulic properties. Disregarding these factors may confound the interpretation of infiltration and runoff results.
ph: (865) 576-8401 fax: (865) 576-5728 email: reports@adonis.osti.gov Available to the public fro... more ph: (865) 576-8401 fax: (865) 576-5728 email: reports@adonis.osti.gov Available to the public from the National Technical Information Service, U.S. Department of Commerce, 5285 Port Royal Rd., Springfield, VA 22161 ph: (800) 553-6847 fax: (703) 605-6900 email: orders@ntis.fedworld.gov online ordering: http://www.ntis.gov/ordering.htm
Information on subsurface processes is required for a broad range of applications, including site... more Information on subsurface processes is required for a broad range of applications, including site remediation, groundwater management, fossil fuel production and CO2 sequestration. Data on these processes is obtained from diverse sensor networks, includes physical, hydrological and chemical sensors and semi permanent geophysical sensors (mainly seismic and resistivity). Currently, processing is done by specialists through the use of commercial and research software packages such as numerical inverse and forward models, statistical data analysis software and visualization and data presentation packages. Information is presented to stakeholders as tables, images and reports. Processing steps, data and assumptions used for information generation are mostly opaque to endusers. As data migrates between applications the steps taken in each application (e.g. in data reduction)are often only partly documented, resulting in irreproducible results. In this approach, interactive tuning of data processing in a systematic way (e.g. changing model parameters, visualization parameters or data used) or using data processing as a discovery tool is de facto impossible. We implemented a web accessible scientific workflow system for subsurface performance monitoring. This system integrates distributed, automated data acquisition from autonomous sensor networks with server side data management and information visualization through flexible browser based data access tools. Webservices are used for communication with the sensor networks and interaction with applications. This system was originally developed for a monitoring network at the Gilt Edge Mine Superfund site, but has now been implemented for a range of different sensor networks of different complexity. The workflow framework allows for rapid and easy integration in a modular, transparent and reproducible manner of a multitude of existing applications for data analysis and processes. By embedding applications in webservice wrappers existing applications can be used without any recoding. Webservices are used for application configuration, resource allocation and communication of data and parameters. We implemented both the statistical package R as well as geophysical inverse codes and hydrological forward models as webservices. This framework and implementation allows for reproducible, transparent result generation by a diverse user base through an easy to use web interface. The use of webservices allows this system to integrate seamlessly with current and future efforts in distributed computing.
An automated tension infiltrometer useful for a range of water tensions from 0.02 to 0.50 m and f... more An automated tension infiltrometer useful for a range of water tensions from 0.02 to 0.50 m and for infiltration rates of 1 x 10 8 to 5 x 1(H m s ' is described. Infiltration rates are calculated from the change in water height in a Mariotte column. Water height is automatically measured by using the difference in tension between two pressure transducers, one installed at the top, and the other at the bottom, of the Mariotte column. Precision of water height measurement using two transducers (SD = 2.2 mm) is increased as compared with height measurements made with only one transducer (SD = 6.2 mm). With only one transducer, much of the measurement error is due to tension fluctuations or "noise" caused by bubbling in the Mariotte column. The new design also incorporates several features used or suggested by other workers. A bubble tower is used for tension regulation, and interchangeable Mariotte columns of different diameters are used to match column volume with expected cumulative infiltration. Advantages of the new device include (i) quick and accurate tension control at low tensions, (ii) improved measurement precision at low flow rates, and (iii) automatic measurement and data collection, which increases measurement speed and eliminates bubbling-induced variability.
Spatial variability of surface hydraulic properties and the extrinsic (e.g., traffic, cropping, e... more Spatial variability of surface hydraulic properties and the extrinsic (e.g., traffic, cropping, etc.) and intrinsic (e.g., soil type, pore size distribution, etc.) factors associated with these properties are important for infiltration and runoff processes in agricultural fields. Disc infiltrometers measured infiltration at 296 sites arranged on two parallel transects. To examine and differentiate the factors contributing to spatial structure under different field conditions these measurements were made in the corn rows, no-track interrows, and wheel track interrows of the field using four different soil water tensions * (0, 30, 60, and 150 mm). Unsaturated hydraulic conductivity (K) and saturated hydraulic conductivity (K,) were maximum in the corn rows and minimum in wheel track inter-rows, with no-track interrows intermediate. Exponents (CZ parameters) of K, and K relationships (K = K, exp -aV) for corn rows and no-track interrows were not significantly different from each other but were significantly different from Q for the wheel track interrows at P = 0.01 level. Spatial variability of K and K, values showed some pseudoproportional effect in nugget variance for all three field conditions. No-track interrows clearly showed an inverse trend for semivariogram of K with changing tension (q) values, whereas differences were found for corn rows and wheel traffic interrows. The spatial structure of (Y for all three field conditions were mostly white noise. Under corn rows, in addition to random variation, a small five-row periodic variation at the P = 0.20 level, matching the five-row traffic configuration, was discovered. The spatial structure of a was influenced by soil type for the no-track interrows. Spatial structure was absent in wheel track interrows, indicating the destruction of pore structure due to compaction. and Luxmoore, 1986; Wilson and Luxmoore, 1988] revealed that more than 70% of water flux can move through the macropores. Meek et al. [ 1989] found 2 to 3 times increase in the infiltration rates over a 3-year period for a field under flood irrigation practice planted to alfalfa. The authors attributed the increase to flow through root channels. Shirmohammadi and Skaggs [1984] conducted experiments to determine the effects of different factors including plant cover on infiltration into columns of fine sand. They found that fescue roots loosened the soil and increased the hydraulic conductivity by an average of 40% over soybeans and 80% over bare soil. Surface soil conditions, resulting from different tillage practices and/or wheel traffic compaction, likely will contribute to spatial variation of the soil macroporosity, thereby altering the hydraulic properties. Disregarding these factors may confound the interpretation of infiltration and runoff results.
Tillage and wheel-traffic compaction alter pore structure and hydraulic properties of agricultura... more Tillage and wheel-traffic compaction alter pore structure and hydraulic properties of agricultural soils. These alterations will affect root growth and movement of water and solutes. This study was conducted to develop new methods needed to characterize the effects of wheel traffic and tillage on pore structure as measured by water flow through macropores. Unconfined (three-dimensional) saturated and unsaturated infiltration measurements (0-, 30-, 60-, and 150mm water tension) at the soil surface were taken sequentially at field sites to determine the steady-state rate of water flow through different pore-size classes on a Tama silty clay loam (fine-silty, mixed, mesic Typic Argiudoll). A tension infiltrometer was used to obtain the unsaturated infiltration rates. Sites were selected on trafficked and untrafficked interrow positions in two tillage systems (chisel plow and no-till). Steady-state infiltration rates from 2 to 300 ion s" 1 were measured. Increasing the tension of applied water resulted in decreasing infiltration rates for both tillages and traffic treatments because, as tensions increased, larger pores emptied. Wheel traffic reduced infiltration rates in both tillages, but caused a greater decrease in infiltration rates in the chisel-plow system than in no-till. Increasing tension caused proportionately smaller decreases in infiltration rates for wheel-trafficked positions. This suggests that larger macropores were transporting a greater proportion of the total water flow in untrafficked soil than in trafficked soil and reinforces the concept that larger, as opposed to smaller, pores are more easily destroyed by wheel traffic. Unconfined infiltration measurements were shown to be useful in quantifying the effects of tillage and compaction on soil macropores.
Spatial variability of surface hydraulic properties and the extrinsic (e.g., traffic, cropping, e... more Spatial variability of surface hydraulic properties and the extrinsic (e.g., traffic, cropping, etc.) and intrinsic (e.g., soil type, pore size distribution, etc.) factors associated with these properties are important for infiltration and runoff processes in agricultural fields. Disc infiltrometers measured infiltration at 296 sites arranged on two parallel transects. To examine and differentiate the factors contributing to spatial structure under different field conditions these measurements were made in the corn rows, no-track interrows, and wheel track interrows of the field using four different soil water tensions Ψ (0, 30, 60, and 150 mm). Unsaturated hydraulic conductivity (K) and saturated hydraulic conductivity (Ks) were maximum in the corn rows and minimum in wheel track interrows, with no-track interrows intermediate. Exponents (α parameters) of Ks and K relationships (K = Ks exp-αΨ) for corn rows and no-track interrows were not significantly different from each other but were significantly different from a for the wheel track interrows at P = 0.01 level. Spatial variability of K and Ks values showed some pseudoproportional effect in nugget variance for all three field conditions. No-track interrows clearly showed an inverse trend for semivariogram of K with changing tension (Ψ) values, whereas differences were found for corn rows and wheel traffic interrows. The spatial structure of a for all three field conditions were mostly white noise. Under corn rows, in addition to random variation, a small five-row periodic variation at the P = 0.20 level, matching the five-row traffic configuration, was discovered. The spatial structure of α was influenced by soil type for the no-track interrows. Spatial structure was absent in wheel track interrows, indicating the destruction of pore structure due to compaction.
Long-term performance of a waste-containment facility liner system can be simply and inexpensivel... more Long-term performance of a waste-containment facility liner system can be simply and inexpensively monitored in dry climates by relative humidity measurements. An increase in humidity as atmospheric air is circulated through a dry coarse layer within the liner system indicates imminent movement of water into the layer. Continued airflow will evaporate and remove water, thereby restoring the coarse layer to
A new method is proposed for determining in situ unsaturated hydraulic conductivities from unsatu... more A new method is proposed for determining in situ unsaturated hydraulic conductivities from unsaturated infiltration measurements made at several tensions on the same infiltration surface. Wooding's equation for steady-state unconfined infiltration rates is used in calculating hydraulic conductivities. Hydraulic conductivities calculated with the new method are consistent with unit gradient laboratory measurements of saturated and unsaturated hydraulic conductivity. This simple field method is potentially valuable because it is faster than unit gradient laboratory methods, and it is less disruptive of pore continuity than other field infiltration techniques.
Traffic effects on pore structure and hydraulic properties of soils may be affected by site-speci... more Traffic effects on pore structure and hydraulic properties of soils may be affected by site-specific factors. The objective of this study was to determine if the effects of wheel traffic on infiltration rates in chisel-plow and no-till tillage systems differed among five Midwestern locations. Ponded and unsaturated (30-, 60-, and 150-nun water tension head) infiltration rates were measured sequentially using infiltrometers after removing surface residues and the upper 2 cm of soil. Wheel traffic reduced ponded infiltration rates in both tillage systems at all locations, ranging from 95% in the chisel-plow system in Iowa to approximately 55% in the chisel-plow system in Missouri. Tillage systems significantly affected ponded infiltration rates at only two of the locations. At the Minnesota and Nebraska locations, no-till reduced ponded infiltration rates in untrafficked interrows by 33 and 64%, respectively, compared with those in the chisel-plow system. Ponded infiltration rates of trafficked interrows did not differ between tillage systems at any location. At the Iowa and Nebraska locations, the decrease in infiltration rate with an increase in tension head was greater for untrafficked interrows than for trafficked interrows in the chisel-plow system. The large pores that drain at 30 mm of tension head accounted for a lower percentage of the water flow with ponding in trafficked interrows (73%) than in untrafficked interrows (88%). Infiltration rate comparisons between tillage systems should consider wheel traffic patterns.
Effective porosity in solute-transport analyses is usually estimated rather than calculated from... more Effective porosity in solute-transport analyses is usually estimated rather than calculated from tracer tests in the field or laboratory. Calculated values of effective porosity in the laboratory on three different textured samples were compared to estimates derived from particle-size distributions and soil–water characteristic curves. The agreement was poor and it seems that no clear relationships exist between effective porosity calculated from laboratory tracer tests and effective porosity estimated from particle-size distributions and soil–water characteristic curves. A field tracer test in a sand-and-gravel aquifer produced a calculated effective porosity of approximately 0.17. By comparison, estimates of effective porosity from textural data, moisture retention, and published values were approximately 50–90% greater than the field calibrated value. Thus, estimation of effective porosity for chemical transport is highly dependent on the chosen transport model and is best obtained by laboratory or field tracer tests. La porosité effective dans les analyses de transport de soluté est habituellement estimée, plutôt que calculée à partir d'expériences de traçage sur le terrain ou au laboratoire. Les valeurs calculées de la porosité effective au laboratoire sur trois échantillons de textures différentes ont été comparées aux estimations provenant de distributions de taille de particules et de courbes caractéristiques sol-eau. La concordance était plutôt faible et il semble qu'il n'existe aucune relation claire entre la porosité effective calculée à partir des expériences de traçage au laboratoire et la porosité effective estimée à partir des distributions de taille de particules et de courbes caractéristiques sol-eau. Une expérience de traçage de terrain dans un aquifère de sables et de graviers a fourni une porosité effective calculée d'environ 0,17. En comparaison, les estimations de porosité effective de données de texture, de teneur en eau et les valeurs publiées étaient environ 50 à 90% plus fortes que la valeur calibrée sur le terrain. Ainsi, l'estimation de la porosité effective pour le transport en solution dépend fortement du modèle de transport utilisé et est préférable lorsqu'elle est obtenue à partir d'expériences de traçage de laboratoire ou de terrain. La porosidad efectiva en el análisis del transporte de solutos se suele estimar, en lugar de calcularse a partir de ensayos de trazadores en el campo o el laboratorio. Los valores calculados de la porosidad efectiva en el laboratorio en tres muestras de distintas texturas se compararon con las estimaciones realizadas a partir de las distribuciones de tamaño de partículas y de las curvas características suelo-agua. El ajuste fue bastante pobre y parece que no existe una relación clara entre los valores de la porosidad efectiva calculados mediante los tres métodos. Un ensayo de trazadores en el campo, en un acuífero formado por arenas y gravas, dio lugar a un valor de porosidad efectiva calculado de 0.17. Las estimaciones realizadas a partir de los datos de textura, humedad retenida y valores publicados eran entre un 50–90 por ciento mayores que el valor calibrado en el ensayo de campo. Así, la estimación del valor de la porosidad efectiva para el transporte químico depende mucho del modelo de transporte seleccionado y es mejor si se obtiene a partir de ensayos de laboratorio o de campo.
Automated and autonomous monitoring of environmental conditions can be used to improve operationa... more Automated and autonomous monitoring of environmental conditions can be used to improve operational efficiency, verify remedial action decisions, and promote confidence in the monitoring process by making data and associated derived information readily accessible to regulators and stakeholders. Ultimately autonomous monitoring systems can reduce overall costs associated with regulatory compliance of performance and long- term monitoring. As part of a joint decision between DOE and the WA Department of Ecology to put on "cold standby" a pump and treat system that has been operating on the Department of Energy's Hanford site in Washington State since 1995, a web site was developed to display the automated water level network around the pump and treat system. The automated water level network consists of nineteen wells with water level transducers and temperature and conductivity probes for selected wells. Data from this network will be used to evaluate the impacts of the pump-and-treat system and the response of the aquifer to shutdown of the system. The website will provide access to data from the automated network along with additional information pertaining to the shutdown of the pump and treat system to the various stakeholders in a convenient and timely fashion. This will allow the various stakeholders to observe the impacts of the shutdown as the aquifer responds. There are future plans to expand this web-based data reporting platform to other environmental data that pertains to the various remedial actions planned at the Hanford site. The benefits of the web site application for monitoring and stewardship are: consistency of data processing and analyses with automated and on demand data and information delivery. The system and data access is password controlled and access to various data or fields can be restricted to specified users. An important feature is that the stakeholders have access to the data in near-real time providing a checks-and-balance system that can potentially increase confidence in the remedy selection.
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