A) Schematic diagram of an infiltrometer. I) Main reservoir (Mariotte), II) rubber stoppers, III) bubbling tubing, IV) water outlet, V) stop valve, VI) metallic ring, VII) purge and measurement of hydraulic load, VIII) stand base, IX) constant hydraulic load, X) insertion depth, XI) pressure sensor access to air chamber, XII) data logger, XII) pressure sensor access to the water column. B) Classical infiltration data results showing the transient and steady state phases of the infiltration process. acknowledge the need for instrumentation and data recording devices (infiltrometer and permeameter) to automate the data acquisition, minimize human errors and reduce the time spent in taking measurements (Amezketa-Lizarraga et al., 2002; Johnson et al., 2005). Therefore many devices have been reported and patented since the 1940s (Bull, 1949) to try to automate the data acquisition process. Automated devices rely on data recording units (data loggers). However the main constraint is the local availability of such equipment, followed by cost. In many cases researchers implement their own devices without automation, such as a double ring infiltrometer (Carlon-Allende, 2006). Automating an infiltrometer requires accurate measurement of the change of height of the water column over time, as the water is allowed to exit the container. Some of the methods used for measuring the column height are the use of paired infrared sensors in a plastic cylinder (Wilson et al., 2000), float valve system with meter spool ring infiltrometer (Amezketa-Lizárraga et al., 2002), Time domain reflectometry (TDR) infrared detectors and float sensor or pressure sensors (Ankeny et al., 1988). The use of pressure transducers is probably the most common choice because of low-cost, simplicity, easy implementation and reliability. Overman et al. (1968) reported the application of pressure transducers since the mid 60s, to implement a variable load laboratory infiltrometer, designed specifically for low-permeability materials. Constanz & Murphy (1987) generated a system that could measure the height of a column of water from pressure changes in a Mariotte reservoir and thus infer the infiltration data. Their instrument used Transamerica CEC 4-312 pressure transducers, with pressure range ± 12.5 psi. The automated device allowed rapid data acquisition with minimal supervision. Ankeny et al. (1988) reported that the use of one transducer produced measurement errors due to bubbling inside the container and adapted the design of Constanz & Murphy (1987) to a tension infiltrometer (disc) with two PX-136 

A) Schematic diagram of an infiltrometer. I) Main reservoir (Mariotte), II) rubber stoppers, III) bubbling tubing, IV) water outlet, V) stop valve, VI) metallic ring, VII) purge and measurement of hydraulic load, VIII) stand base, IX) constant hydraulic load, X) insertion depth, XI) pressure sensor access to air chamber, XII) data logger, XII) pressure sensor access to the water column. B) Classical infiltration data results showing the transient and steady state phases of the infiltration process. acknowledge the need for instrumentation and data recording devices (infiltrometer and permeameter) to automate the data acquisition, minimize human errors and reduce the time spent in taking measurements (Amezketa-Lizarraga et al., 2002; Johnson et al., 2005). Therefore many devices have been reported and patented since the 1940s (Bull, 1949) to try to automate the data acquisition process. Automated devices rely on data recording units (data loggers). However the main constraint is the local availability of such equipment, followed by cost. In many cases researchers implement their own devices without automation, such as a double ring infiltrometer (Carlon-Allende, 2006). Automating an infiltrometer requires accurate measurement of the change of height of the water column over time, as the water is allowed to exit the container. Some of the methods used for measuring the column height are the use of paired infrared sensors in a plastic cylinder (Wilson et al., 2000), float valve system with meter spool ring infiltrometer (Amezketa-Lizárraga et al., 2002), Time domain reflectometry (TDR) infrared detectors and float sensor or pressure sensors (Ankeny et al., 1988). The use of pressure transducers is probably the most common choice because of low-cost, simplicity, easy implementation and reliability. Overman et al. (1968) reported the application of pressure transducers since the mid 60s, to implement a variable load laboratory infiltrometer, designed specifically for low-permeability materials. Constanz & Murphy (1987) generated a system that could measure the height of a column of water from pressure changes in a Mariotte reservoir and thus infer the infiltration data. Their instrument used Transamerica CEC 4-312 pressure transducers, with pressure range ± 12.5 psi. The automated device allowed rapid data acquisition with minimal supervision. Ankeny et al. (1988) reported that the use of one transducer produced measurement errors due to bubbling inside the container and adapted the design of Constanz & Murphy (1987) to a tension infiltrometer (disc) with two PX-136 

Contexts in source publication

Context 1
... measurements ( Dudley et al., 2003;Seyfried & Murdock, 2004), radiation-based measurements (Simpson, 2006) image analysis ( Gimmi & Ursino, 2004) and multimodal instruments (Pedro Vaz et al., 2001;Schwartz & Evett, 2003) that permit measurement of several variables simultaneously. The infiltrometer is a very popular instrument among researchers (Fig. 1A), because knowledge of soil hydraulic properties is a key factor in understanding their impact on hydrological processes such as infiltration ( Esteves et al., 2005) the superficial flow and aquifer recharge. Basic infiltrometers are relatively simple devices, which essentially consist of a reservoir (fitted with a graduated scale), a ...
Context 2
... inserted into the soil, and a stop valve. A test is conducted by allowing the liquid to exit the container, either directly or through a pipe into the ring, measuring the rate of water infiltration while maintaining a small positive pressure on the fluid. The infiltration process consists of two main parts: the transient and steady state (Fig. 1B). The transient state occurs from the beginning of the experiment up to the time when a constant rate of water infiltration is ...
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... amplifiers are a type of differential amplifier with high input impedance and adjustable gain that constitute essential building blocks in analogue electronics. One of the classical configurations of instrumentation amplifiers uses three operational amplifiers to form a two-stage amplifying circuit ( Figure 10). The differential input signal feeds the first amplifying stage formed by op-amp 1 and op- amp 2. The output between both op-amp 1 and op-amp 2 (Va and Vb respectively) is differential weighted version of the input voltage. ...
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... of instrumentation amplifiers have resulted in multiple versatile commercial integrated circuits, with impressive operating characteristics, that allow gain adjustment using a single variable resistor and/or digital signals. One particular integrated circuit that is suitable for portable applications is the INA125 from Texas Instruments© (Fig. 11). The INA125 also incorporates a selectable voltage reference circuit, which will be used to supply the reference voltage to the pressure transducer (Fig. 12). The INA125 is a low power device (quiescent current 460 µA) and can operate over a wide range of voltages from a single power supply (2.7V to 36V) or dual supply (±1.35V to ...
Context 5
... gain adjustment using a single variable resistor and/or digital signals. One particular integrated circuit that is suitable for portable applications is the INA125 from Texas Instruments© (Fig. 11). The INA125 also incorporates a selectable voltage reference circuit, which will be used to supply the reference voltage to the pressure transducer (Fig. 12). The INA125 is a low power device (quiescent current 460 µA) and can operate over a wide range of voltages from a single power supply (2.7V to 36V) or dual supply (±1.35V to ±18V), which makes it suitable for battery powered applications. The voltage reference value can be adjusted using the jumper J5, to provide 10V, 5V, 2.5 V or ...
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... complete circuit is shown in Figure 13. The design includes an on-off switch and connectors to calibrate and monitor the output voltage using a multimeter. ...
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... there is tap water available nearby. However, carrying all the necessary materials in field tests may be a difficult task. Therefore the size of the reservoir and metallic ring is a compromise. The infiltrometer described here uses a 1 metre long, 6.35 cm diameter perpex pipe; the ring is made of an iron pipe (8.0 cm long and 8.8 cm diameter) . Fig. 14 shows the infiltrometer design and assembly, including instrumentation circuitry. Fig. 13. Instrumentation circuit for measuring infiltration data using a pressure transducer. Fig. 14. A) Designed infiltrometer. B) close-up of the pressure sensor assembly. C) The single-sided circuit is fitted into a small (2.6" X 2.2") printed circuit ...
Context 8
... tests may be a difficult task. Therefore the size of the reservoir and metallic ring is a compromise. The infiltrometer described here uses a 1 metre long, 6.35 cm diameter perpex pipe; the ring is made of an iron pipe (8.0 cm long and 8.8 cm diameter) . Fig. 14 shows the infiltrometer design and assembly, including instrumentation circuitry. Fig. 13. Instrumentation circuit for measuring infiltration data using a pressure transducer. Fig. 14. A) Designed infiltrometer. B) close-up of the pressure sensor assembly. C) The single-sided circuit is fitted into a small (2.6" X 2.2") printed circuit board fits into the plastic ...
Context 9
... compromise. The infiltrometer described here uses a 1 metre long, 6.35 cm diameter perpex pipe; the ring is made of an iron pipe (8.0 cm long and 8.8 cm diameter) . Fig. 14 shows the infiltrometer design and assembly, including instrumentation circuitry. Fig. 13. Instrumentation circuit for measuring infiltration data using a pressure transducer. Fig. 14. A) Designed infiltrometer. B) close-up of the pressure sensor assembly. C) The single-sided circuit is fitted into a small (2.6" X 2.2") printed circuit board fits into the plastic ...
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... infiltrometer was tested in two different test locations around the Cuitzeo Lake watershed (19º58' N, 101º08' W): sandy loam (Fig. 15A) and sandy soil (Fig. 15B). The results from the automated measurement data acquisition system are much more consistent throughout the test, improving the quality of information compared to visual observations. Table 2 shows a summary of hydraulic conductivity results, using the Wu2 method and data from the steady state region. The ...
Context 11
... infiltrometer was tested in two different test locations around the Cuitzeo Lake watershed (19º58' N, 101º08' W): sandy loam (Fig. 15A) and sandy soil (Fig. 15B). The results from the automated measurement data acquisition system are much more consistent throughout the test, improving the quality of information compared to visual observations. Table 2 shows a summary of hydraulic conductivity results, using the Wu2 method and data from the steady state region. The automated infiltrometer can ...
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... test has been concluded. Higher resolution may also be required for correct in-situ characterization of different types of soils. Moreover, since measurements are not taken continuously (i. e. the lowest sampling rate may be 1 second) it may be desirable to be able to shutdown the analogue circuitry in between measurements to extend battery life. Fig. 16 shows the schematic diagram of the proposed data acquisition system. Fig. 16. Schematic diagram of a data acquisition system based on a low power microcontroller, specially designed for hydraulic infiltration ...
Context 13
... characterization of different types of soils. Moreover, since measurements are not taken continuously (i. e. the lowest sampling rate may be 1 second) it may be desirable to be able to shutdown the analogue circuitry in between measurements to extend battery life. Fig. 16 shows the schematic diagram of the proposed data acquisition system. Fig. 16. Schematic diagram of a data acquisition system based on a low power microcontroller, specially designed for hydraulic infiltration ...
Context 14
... powerful microcontrollers are available from multiple companies that can be used to perform all the necessary data acquisition and signal processing operations. One particularly useful family of powerful microcontrollers suitable for low power operation is the MSP430 series from Texas Instruments© (Fig. 17). Case study 2 is based on MSP430F149IPAG microcontroller from Texas Instruments©. The MSP430 is a 16-bit RISC, ultra-low-power device with five power-saving modes, two built-in 16-bit timers, a fast 12- bit A/D converter, two universal serial synchronous/asynchronous communication interfaces (USART), 48 Input/Output pins, 60 kB of ...
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... memory block 0x3F. Before each test, the microcontroller detects which memory blocks are used and starts saving data in the next empty block. Thus, up to 90 tests can be conducted in- situ. The user can also select which memory block to erase, (i.e. which experiment) instead of erasing the entire memory, also contributing to saving battery life. Fig. 18A shows the double-sided printed circuit board. The board, keyboard and display and battery are fitted into a plastic enclosure (Fig 18B, 18C). In a similar manner to case study one, the pressure transducer is located below the reservoir and the wires carrying the voltage supply and signals are connected to the data logger. Fig. 18. A) ...
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... 18A shows the double-sided printed circuit board. The board, keyboard and display and battery are fitted into a plastic enclosure (Fig 18B, 18C). In a similar manner to case study one, the pressure transducer is located below the reservoir and the wires carrying the voltage supply and signals are connected to the data logger. ...
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... battery life. Fig. 18A shows the double-sided printed circuit board. The board, keyboard and display and battery are fitted into a plastic enclosure (Fig 18B, 18C). In a similar manner to case study one, the pressure transducer is located below the reservoir and the wires carrying the voltage supply and signals are connected to the data logger. Fig. 18. A) Data Logger Printed Circuit Board (PCB). B) The PCB, C) keyboard and display and interface connections are also fitted in the plastic ...
Context 18
... C++ program interface was implemented to allow the user to transfer the data to a host PC for permanent storage, off-line results visualization and analysis (Fig. 19). Prior to each test the user can set the time, date and sampling rate for the experiment. The test information is stored at the beginning of each memory block, followed by the column height measurements. Once the experiment (or several experiments) has been completed, the user can review the measured data in-situ. Alternatively the ...
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... memory block, followed by the column height measurements. Once the experiment (or several experiments) has been completed, the user can review the measured data in-situ. Alternatively the user can transfer the results to a host PC, through the RS232 connection or with RS232-USB adaptors, to allow compatibility with current PC configuration ports. Fig. 19. A) The C++ software B) analyses the measurements using the Wu1 and Wu2 methods and C) plots the ...
Context 20
... software processes the data and allows inspection of each value ( Figure 18B). The program calculates hydraulic conductivity using the WU1 and WU2 methods, thus allowing result comparison. ...

Citations

... van Genuchten (1980); Durner (1994); Durner and Flühler (2006)). Hydraulic conductivity can be considered as an indispensable parameter for soil characterization, simulation of water and mass transport in vadose and saturated zone, management of soil organic matter and sustainable development of regional water resources (Gutierrez Gnecchi et al., 2011). ...
... Empirical methods based on systematic data collection are used as to correlate K s with soil properties like particle size, soil texture, pore size and relative effective porosity (Gootman et al., 2020;Gupta et al., 2020;Huang et al., 2019;Hwang et al., 2017;Picciafuoco et al., 2019;Vereecken et al., 2010Vereecken et al., , 1992Wösten et al., 1999). Experimental methods are distinguished in laboratory and field methods (Durner and Flühler, 2006;Gutierrez Gnecchi et al., 2011;Morbidelli et al., 2017). However, the adequacy and cost-effectiveness of these methods can often be a limiting factor in soil-water modeling applications. ...
... However, the adequacy and cost-effectiveness of these methods can often be a limiting factor in soil-water modeling applications. In this concept, although the number of methods and apparatuses used is quite large, it is still a need to elaborate new methodological approaches and instrumentation technologies to enhance the quality and quantity of reliable information and to provide alternative options to address the uncertainty of hydraulic parameters estimations (Gamie and De Smedt, 2018;Gutierrez Gnecchi et al., 2011;Zhang et al., 2007). A physical analogue for soil water movement can be modelled with the Hele-Shaw (Hele-Shaw, 1898) apparatus. ...
Article
The estimation of saturated hydraulic conductivity is a key parameter for studying the water flow in the unsaturated zone of the soil. In this work, a combined modelling approach of the waterfront movement is elaborated, integrating a physical analogue type device with image analysis. A customized Hele-Shaw apparatus is designed for the wetting process visual inspection, while an optical flow algorithm is used for the numerical calculation of flow velocity and saturated hydraulic conductivity values at a pixel level of the image processing. Saturated hydraulic conductivity values estimated by the proposed method are in close agreement with values found in the literature under similar soil conditions. Also, the proposed method seems to be a useful tool for a comprehensive analysis of the waterfront movement in the vadose zone.
Article
Permeability is a vital parameter for the design and construction of structures involving ocean engineering. Based on the steady-state heat transfer theory and Darcy's law, a novel in-situ test method for permeability in saturated sandy porous media is introduced in this work. This approach aims to obtain permeability through the inversion of the measured temperatures. Temperatures measuring device with a constant heater was installed in an insulating experimental tank filled with sandy sediments of different permeability. Further, a numerical model based on the Finite Element method was simulated to validate the feasibility of the proposed method and accuracy of the experimental data. Besides, the results obtained by the constant head test were compared with those calculated by the novel in-situ test method, considering different surface temperatures of the heater and different sediments’ permeability. It shows that the permeability obtained by in-situ method are reliable and accurate (the accuracy is within one order of magnitude) in both numerical simulations and experimental tests. The effects of different surface temperatures of the heater and permeability of porous media on permeability calculation results were also discussed. The surface temperature was found that has little influence on permeability. And the proposed method is applicable when the permeability is higher than 10⁻¹² m². The findings can provide some reference to the in-situ measurement of submarine sediments' permeability.