scholarly journals Determining the Relation between Groundwater Flow Velocities and Measured Temperature Differences Using Active Heating-Distributed Temperature Sensing

Water ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1619 ◽  
Author(s):  
Bakx ◽  
Doornenbal ◽  
Weesep ◽  
Bense ◽  
Essink ◽  
...  
Keyword(s):  
Groundwater Flow ◽  
Flow Velocity ◽  
Temperature Response ◽  
Flow Equation ◽  
Absolute Temperature ◽  
Temperature Sensing ◽  
Measured Temperature ◽  
Distributed Temperature Sensing ◽  
Plan View ◽  
Flow Velocities

Active Heating-Distributed Temperature Sensing (AH-DTS) has the potential to allow for the measurement of groundwater flow velocities in situ. We placed DTS fiber-optic cables combined with a heating wire in direct contact with aquifer sediments in a laboratory scale groundwater flow simulator. Using this setup, we empirically determined the relationship between ΔT, the temperature difference by constant and uniform heating of the DTS cable and the background temperature of the groundwater system, and horizontal groundwater flow velocity. Second, we simulated the observed temperature response of the system using a plan-view heat transfer flow model to calibrate for the thermal properties of the sediment and to optimize cable setup for sensitivity to variation in groundwater flow velocities. Additionally, we derived an analytical solution based on the heat flow equation that can be used to explicitly calculate flow velocity from measured ΔT for this specific AH-DTS cable setup. We expect that this equation, after calibration for cable constitution, is valid for estimating groundwater flow velocity based on absolute temperature differences measured in field applications using this cable setup.

Investigating Taylor’s frozen turbulence hypothesis in the surface layer at an ideal desert field site using fibre-optic distributed temperature sensing

2021 ◽  
Author(s):  
Rainer Hilland ◽  
Andreas Christen ◽  
Roland Vogt
Keyword(s):  
Boundary Layer ◽  
Sonic Anemometer ◽  
Field Work ◽  
Field Investigation ◽  
Temperature Sensing ◽  
Temperature Fields ◽  
Fibre Optic ◽  
Distributed Temperature Sensing ◽  
Plan View ◽  
Wide Range

<p>Taylor’s frozen turbulence hypothesis is the most critical assumption through which time-resolving sensors may be used to derive statistics of the turbulent spatial field. Namely, it relates temporal autocorrelation to spatial correlation via the mean wind speed and is invoked in almost all boundary layer field work. Nevertheless, the conditions and scales over which Taylor’s hypothesis is valid remain poorly understood in the atmospheric boundary layer.</p> <p>As part of the Namib Turbulence Experiment (NamTEX) campaign in March 2020, a pseudo-3D fibre-optic distributed temperature sensing (DTS) array was installed within a 300 x 300 m area in the Namib desert. The array is X-shaped in plan view and contains 16 measurement heights from 0.45 m to 2.85 m. Fibre-optic sensing provides air temperature measurements at unprecedented spatio-temporal density (0.25 m horizontally, 0.17 m vertically, and 1 Hz) and was coupled with a vertical array of traditional sonic anemometer point measurements to investigate the relationship between spatial and temporal temperature fields. The Namib provides an ideal location for fundamental boundary layer research: homogenous flat surfaces, no vegetation, little moisture, strong solar forcing, regular and repeated clear-sky conditions, and a wide range of atmospheric stabilities.</p> <p>Using the NamTEX DTS array we present the first field investigation of Taylor’s hypothesis that considers boundary layer stability and is independent of wind direction. A novel method of 2d horizontal cross-correlation between all possible points of a single height of the DTS is employed to produce spatial ‘maps’ of the turbulent flow, whose velocity, direction, and size may be tracked through time.</p>

scholarly journals Monitoring the Hydraulic Performance of Sewers Using Fibre Optic Distributed Temperature Sensing

Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2451
Author(s):  
Cedric Kechavarzi ◽  
Philip Keenan ◽  
Xiaomin Xu ◽  
Yi Rui
Keyword(s):  
Flow Velocity ◽  
Treatment Plant ◽  
Heavy Rain ◽  
Water Treatment Plant ◽  
Hydraulic Performance ◽  
Temperature Sensing ◽  
Fibre Optic ◽  
Distributed Temperature Sensing ◽  
Water Flow Velocity ◽  
Sewer Network

The hydraulic performance of sewers is a major public concern in industrialised countries. In this study, fibre optic distributed temperature sensing (DTS) is used to monitor the discharge of wastewater for three months to assess the performance of a long underground foul sewer in a village in the UK. DTS cables were installed in the invert of sewer pipes to obtain distributed temperature change data along the sewer network. DTS generates a series of two-dimensional data sets (temperature against distance) that can be visualised in waterfall plots to help identify anomalies. The spatial and temperature resolutions are 2 m and 0.2–0.3 °C, respectively. The monitoring data clearly identify high-temperature plumes, which represent the flow of household wastewater in the sewer. Based on the analysis of the waterfall plots, it is found that the flow velocity is about 0.14 m/s under normal conditions. When continuous moderate rain or heavy rain occurs, water backs up from the water treatment plant to upstream distances of up to 400 m and the water flow velocity in the sewer decreases sharply to about 0.03 m/s, which demonstrates the ability of the DTS to localise anomalies in the sewer network.

scholarly journals A distributed heat pulse sensor network for thermo-hydraulic monitoring of the soil subsurface

2020 ◽  
Vol 53 (3) ◽  
pp. 352-365 ◽  
Author(s):  
Corinna Abesser ◽  
Francesco Ciocca ◽  
John Findlay ◽  
David Hannah ◽  
Philip Blaen ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Temporal Dynamics ◽  
Temperature Response ◽  
Soil Disturbance ◽  
Temperature Sensing ◽  
Soil Parameters ◽  
Spatial And Temporal Variability ◽  
Fibre Optic ◽  
Distributed Temperature Sensing ◽  
Content Type

Fibre optic distributed temperature sensing (DTS) is used increasingly for environmental monitoring and subsurface characterization. Combined with heating of metal elements embedded within the fibre optic cable, the temperature response of the soil provides valuable information from which soil parameters such as thermal conductivity and soil moisture can be derived at high spatial and temporal resolution, and over long distances.We present a novel active distributed temperature sensing (A-DTS) system and its application to characterize spatial and temporal dynamics in soil thermal conductivity along a recently forested hillslope in Central England, UK. Compared with conventional techniques (needle probe surveys), A-DTS provided values with a similar spread although lower on average. The larger number of measurement points that A-DTS provides at higher spatial and temporal resolutions and the ability to repeat surveys under different meteorological or hydrological conditions allow for a more detailed examination of the spatial and temporal variability of thermal conductivities at the study site. Although system deployment time and costs are higher than with needle probes, A-DTS can be extremely appealing for applications requiring long-term monitoring, at high temporal repeatability, over long (kilometres) distances and with minimum soil disturbance, compared with one-off spatial surveys.Thematic collection: This article is part of the Measurement and monitoring collection available at: https://www.lyellcollection.org/cc/measurement-and-monitoring

Detection of Small Leaks in Liquid Pipelines Utilizing Distributed Temperature Sensing

2012 ◽  
Author(s):  
Shane P. Siebenaler ◽  
Gary R. Walter
Keyword(s):  
Near Field ◽  
Temperature Response ◽  
Temperature Sensing ◽  
Transient Temperature ◽  
False Alarms ◽  
Distributed Temperature Sensing ◽  
Sensitivity Testing ◽  
Alarm Systems ◽  
Integrity Management ◽  
The Impact

Leaks from hazardous liquid pipelines can have significant impacts on safety and the environment. The detection of such leaks in their infancy is important to the overall integrity management of pipelines. The traditional means of detecting leaks on this infrastructure typically involve visual inspection or computational monitoring. However, such methods are often inadequate for detecting and locating small discharges that can result in damage to the environment. One potential alternative technology is distributed temperature sensing (DTS). The analytical work in this paper details near-field thermal effects surrounding the pipeline, seasonal and diurnal impacts on temperature as a function of buried depth, and the impact of transient temperature response from batch product operations. The analysis demonstrated that DTS employed on a buried transmission line would be immune from many of these effects and would not generate numerous false alarms due to these conditions. Laboratory testing was conducted on both Brillouin and Raman-based DTS systems; a total of four different manufacturer’s products were utilized. The testing characterized any limitations of such systems as a function of wetted length. The testing demonstrated that such technology could accurately detect small temperature fluctuations over distances exceeding 12 km (7.5 mi) to a location with a resolution of one meter. In addition to sensitivity testing of the systems, the automated alarm systems were tested to ensure that the systems could detect leaks without generating numerous false alarms.

scholarly journals Limitations of fibre optic distributed temperature sensing for quantifying surface water groundwater interactions

2014 ◽  
Vol 11 (7) ◽  
pp. 8167-8190 ◽  
Author(s):  
H. Roshan ◽  
M. Young ◽  
M. S. Andersen ◽  
R. I. Acworth
Keyword(s):  
Surface Water ◽  
Temperature Difference ◽  
Groundwater Discharge ◽  
Water Injection ◽  
Temperature Response ◽  
Temperature Sensing ◽  
Hot Water ◽  
Apparent Temperature ◽  
Distributed Temperature Sensing ◽  
Simulated Surface

Abstract. Studies of surface water–groundwater interactions using fiber optic distributed temperature sensing (FO-DTS) has increased in recent years. However, only a few studies to date have explored the limitations of FO-DTS in detecting groundwater discharge to streams. A FO_DTS system was therefore tested in a flume under controlled laboratory conditions for its ability to accurately measure the discharge of hot or cold groundwater into a simulated surface water flow. In the experiment the surface water (SW) and groundwater (GW) velocities, expressed as ratios (vgw/vsw), were varied from 0.21% to 61.7%; temperature difference between SW-GW were varied from 2 to 10 °C; the direction of temperature gradient were varied with both cold and-hot water injection; and two different bed materials were used to investigate their effects on FO_DTS's detection limit of groundwater discharge. The ability of the FO_DTS system to detect the discharge of groundwater of a different temperature in the laboratory environment was found to be mainly dependent upon the surface and groundwater flow velocities and their temperature difference. A correlation was proposed to estimate the groundwater discharge from temperature. The correlation is valid when the ratio of the apparent temperature response to the source temperature difference is above 0.02.

Distributed fibre-optic temperature sensing in a 1 km borehole drilled on a fast-flowing glacier in Greenland

2020 ◽  
Author(s):  
Robert Law ◽  
Poul Christoffersen ◽  
Bryn Hubbard ◽  
Samuel Doyle ◽  
Thomas Chudley ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Temperature Drop ◽  
Greenland Ice Sheet ◽  
Absolute Temperature ◽  
Temperature Sensing ◽  
Hot Water ◽  
Fibre Optic ◽  
Distributed Temperature Sensing ◽  
High Deformation ◽  
Lower Magnitude

<p>Whilst marine-terminating glaciers in Greenland are significant contributors to global sea level rise, their thermodynamics are poorly constrained by observations. Conventional discrete thermistor borehole sensing studies go some way to addressing this but lack the spatial resolution to effectively resolve key processes. Here, we detail results from fibre optic distributed temperature sensing equipment installed in a 1040 m hot water drilled borehole 28 km inland of the calving front of Store Glacier, Greenland. Surface ice velocity at the borehole is 550 m a<sup>-1</sup> with convergent ice flow into a bedrock trough. Spatial resolution of 0.25 m, temperature differences of 0.03 °C, and an absolute temperature accuracy of 0.15 °C were achieved. 0.5 °C warm anomalies were observed between 0-30 and 220-45 m depth with a central cold section down to -22 °C . We interpret the former anomaly to be a result of cryo-hydrologic warming, although of lower magnitude than in slow-flowing sectors of the Greenland Ice Sheet. The latter is theorised to be strain heating, supported by deformation observed in the cable at this point. The record also reveals a 75 m thick section of temperate basal ice and the nature of the cold-temperate transition as a sharp temperature drop of 0.45 °C over 1.5 m at the top of the temperate layer, with notable temperature changes in the vicinity of the transition. Warming of 0.06 °C is observed over the basal 6 m of the profile. The cable lasted 6 weeks before failure, demonstrating the feasibility of using  fibre optic sensing to study thermal processes in a glacier environment with high deformation rates.</p>

scholarly journals Characterizing groundwater flow and heat transport in fractured rock using fiber-optic distributed temperature sensing

2013 ◽  
Vol 40 (10) ◽  
pp. 2055-2059 ◽  
Author(s):  
T. Read ◽  
O. Bour ◽  
V. Bense ◽  
T. Le Borgne ◽  
P. Goderniaux ◽  
...  
Keyword(s):  
Groundwater Flow ◽  
Heat Transport ◽  
Fiber Optic ◽  
Fractured Rock ◽  
Temperature Sensing ◽  
Distributed Temperature Sensing

Groundwater Flow Quantification in Fractured Rock Boreholes Using Active Distributed Temperature Sensing Under Natural Gradient Conditions

2019 ◽  
Vol 55 (4) ◽  
pp. 3285-3306 ◽  
Author(s):  
Carlos H. Maldaner ◽  
Jonathan D. Munn ◽  
Thomas I. Coleman ◽  
John W. Molson ◽  
Beth L. Parker
Keyword(s):  
Groundwater Flow ◽  
Fractured Rock ◽  
Temperature Sensing ◽  
Flow Quantification ◽  
Natural Gradient ◽  
Distributed Temperature Sensing

A possible modification of groundwater flow equation using coordinate transformations

2014 ◽  
Vol 15 (2) ◽  
pp. 278-287 ◽  
Author(s):  
Abdon Atangana ◽  
Ernestine Alabaraoye
Keyword(s):  
Groundwater Flow ◽  
Prolate Spheroid ◽  
Flow Equation ◽  
Time Space ◽  
Adomian Decomposition ◽  
Iteration Methods ◽  
Groundwater Flow Equation ◽  
Factor Α ◽  
Modified Equation ◽  
Good Agreement

We described a groundwater model with prolate spheroid coordinates, and introduced a new parameter, namely τ the silhouette influence of the geometric under which the water flows. At first, we supposed that the silhouette influence approaches zero; under this assumption, the modified equation collapsed to the ordinary groundwater flow equation. We proposed an analytical solution to the standard version of groundwater as a function of time, space and uncertainty factor α. Our proposed solution was in good agreement with experimental data. We presented a good approximation to the exponential integral. We obtained an asymptotic special solution to the modified equation by means of the Adomian decomposition and variational iteration methods.

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