Abstract Groundwater flows through contaminated mine sites are a major concern in many parts of the world. In this study, a variety of instrumentation was used to locate and quantify groundwater inflows into an acid lake on an abandoned mine site in Brandenburg, Germany. While previously-installed piezometers and seepage meters had identified several points of groundwater influx into the lake, such techniques are spatially limited to the point of installation. To address this limitation, a fiber optic distributed temperature sensor (DTS) was deployed across the lake bottom and in vertical profilers to confirm and expand the previously generated data sets. Fiber optic DTS, a relatively new technology, provides the opportunity to measure temperature on very high spatial and temporal scales using Raman spectra scattering of pulsed light within a glass fiber. A 1000 meter cable was deployed spatially along the sediment-water interface to identify spatially scattered areas of groundwater inflow, while two high-resolution probes (which return temperature readings every 2.4 vertical cm) were installed vertically near existing seepage meters. Preliminary analysis of the vertical deployments showed substantial groundwater upwelling, confirming the results of previous seepage meter measurements which showed significant vertical flux into the lake. Ongoing analysis of the lateral deployment is expected to identify areas in which there are anomalies in the diurnal temperature cycle at the lake bottom; such anomalies may indicate groundwater influx into the lake. These areas will be used to locate future seepage meter and piezometers installations. Using Fiber-Optic Distributed Temperature Sensing to Assess Groundwater-Lake Exchange in an Acid Mine Lake in Eastern Germany Mark B. Hausner 1 , Jan H. Fleckenstein 2 , Christiane Neumann 2 , and Scott W. Tyler 3 1. Graduate Program of Hydrologic Sciences, University of Nevada Reno, [email protected] · 2. Department of Hydrology, University of Bayreuth, Bayreuth, Germany · 3. Department of Geological Science and Engineering, University of Nevada Reno, Reno, Nevada Background Lake 77 is an acid mine lake in Eastern Germany where previous studies have found strong influences of groundwater inflow on biogeochemical processes at the lake-groundwater interface. In this study, we: • Deploy a fiber-optic DTS cable laterally along the lake bottom and vertically in the lake substrate to continuously measure temperatures in these areas • Use anomalies in the diurnal temperature wave at the sediment-water interface to identify likely points of groundwater influx to the lake Methods Using Temperature as a Groundwater Tracer Field Deployment AGU Poster OS51D-1284 Results and Discussion after Stonestrom and Constantz, 2003 The high heat capacity of water makes temperature an excellent tool for examining the interactions between groundwater and surface water. Groundwater and surface water have distinct thermal signatures. While surface water shows a high-amplitude temperature cycle (in both annual and diurnal cycling), groundwater tends to be more constant and exhibits dampened temperature cycles on a daily and seasonal basis. These differences can be used to identify and quantify regions of groundwater-surface water interactions. Anti-Stokes Stokes shifts with temperature Brillouin in frequency Raman (Anti-Stokes) in amplitude Rayleigh Scattering Brillouin Raman (Stokes) Frequency Amplitude/ Intensity Hatch, 2008 Fiber optic distributed temperature sensing (DTS) relies on the scattering of light in a glass fiber to measure temperatures at very high spatial and temporal resolutions along a fiber-optic cable. The ratio of the Raman spectra scattered components (the temperature-independent Stokes and temperature-dependent Anti-Stokes signals) and the two-way travel time from the instrument to the point of reflection and back are used to determine the temperature and the location of the point of scattering. Spatial resolutions up to every 2 meters and temporal resolution as fine as 15 seconds can be achieved with this technology. Hatch, C.E., S. Tyler, T. Cluff, M. Hausner, W. Miller, E. Carroll- Moore, and J. Davison (2008), Using distributed temperature sensing to assess soil moisture in agricultural settings, Geological Society of America 2008 Fall Meeting, Houston, Texas. Stonestrom, D.A. and J. Constantz, ed., (2003), Heat as a tool for studying the movement of groundwater near streams, USGS Circular 1260, USGS. Tyler, S.W., J.S. Selker, M.B. Hausner, C.E. Hatch, T. Torgersen, and S.G. Schladow (2007), Environmental temperature sensing using Raman spectra DTS fiber optic methods, Water Resour. Res., in press. Volze, N., C. Neumanne, and J. Fleckenstein (2008), Quantifying the spatial and temporal variability of groundwater – lake exchange. Three fiber optic cables were deployed at the study site – one laterally along the sediment-water interface, and two vertical profilers. The lateral deployment utilized a loose-tube cable with teflon strength members and protective insulation, while the vertical deployments relied on delicate tight-buffered fibers encased in PVC insulation. Volze et al., 2008 Lake 77, with the study area indicated by the gold box. The daily amplitude of the temperature signal (calculated as the difference between the maximum and minimum daily mean temperatures at the lake bottom) is shown below for the length of the cable. Daily amplitude is affected by the depth of water and exposure to sunlight, as well as the potential influence of groundwater fluxes. Areas with localized groundwater influxes will have reduced amplitude when compared to other points of similar depth. Three amplitude phenomena are highlighted on the plots below. Conclusions References • Fiber optic DTS is a feasible technology for use in identifying spatially-scattered temperature anomalies that may be associated with groundwater influxes into a lake. • Additional measurement methods will likely be required to quantify fluxes between surface waters and groundwaters • Fiber-optic cable used in environmental monitoring must be robust and durable to survive the deployment and return reliable data. Fiber-Optic Distributed Temperature Sensing (DTS) • Lateral deployment: cable laid at the sediment-water interface along the lake bottom. 2 meter spatial resolution, 15 minute temporal resolution • Two vertical deployments: fine fiber wrapped around a 2” PVC pipe and installed vertically in the lakebed sediments. 2.2 centimeter vertical resolution, 15 minute temporal resolution The cables used on this site included: Diurnal Lakebed Temperature Profile Increasing Temperature Afternoon Dawn Lake Downward Flux Upward Flux The highlighted points on the above plots show the following phenomena: funding for this research was provided by the: Bavaria California Technology Center (BaCaTeC) http://www.bacatec.de/ The fiber used in the vertical profilers was not robust enough to stand up to the rigors of the field. The laterally- deployed cable returned two days worth of data, presented below. However, peak temperature measurements were affected by an unknown source of interference. As a result, the data presented below will require further investigation. 200 300 400 500 600 700 800 900 1 2 3 4 5 6 7 Distance Along Cable Daily Temperature Amplitude (C) Daily Temperature Amplitude Western Array East-West Transects Northern Array 0 1 2 3 4 5 6 7 0 20 40 60 80 100 120 Daily Temperature Amplitude (C) Water Depth (cm) Temperature Amplitude vs. Depth 200 300 400 500 700 800 900 Daily Temperature Amplitudes Amplitude (°C) Depth of Water (cm) Amplitude (°C) Temperature Amplitude vs. Depth Temperature Amplitude and Water Depth Amplitude (°C) 1.6 6.8 Scale (m) 600 Distance along Cable (m) The field work for this study was conducted in August, 2008. The groundwater flow data collected during this project is one component of a larger study examining the hydrological and geochemical processes at work in the entire mine complex. C:\MBH\DTS Projects\Lake 77, Germany\lake77_1.bmp •Gold Circle: A likely area of groundwater intrusion that requires further investigation. •Red Circle: a quick transition from deeper to shallow water, resulting in an isolated high amplitude point. •Magenta Circle: a shallow, high amplitude area likely affected by solar heating.
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AbstractGroundwater flows through contaminated mine sites are a major concern in many parts of the world. In this study, a variety of instrumentation was used to locate and quantify groundwater inflows into an acid lake on an abandoned mine site in Brandenburg, Germany. While previously-installed piezometers and seepage meters had identified several points of groundwater influx into the lake, such techniques are spatially limited to the point of installation. To address this limitation, a fiber optic distributed temperature sensor (DTS) was deployed across the lake bottom and in vertical profilers to confirm and expand the previously generated data sets. Fiber optic DTS, a relatively new technology, provides the opportunity to measure temperature on very high spatial and temporal scales using Raman spectra scattering of pulsed light within a glass fiber. A 1000 meter cable was deployed spatially along the sediment-water interface to identify spatially scattered areas of groundwater inflow, while two high-resolution probes (which return temperature readings every 2.4 vertical cm) were installed vertically near existing seepage meters. Preliminary analysis of the vertical deployments showed substantial groundwater upwelling, confirming the results of previous seepage meter measurements which showed significant vertical flux into the lake. Ongoing analysis of the lateral deployment is expected to identify areas in which there are anomalies in the diurnal temperature cycle at the lake bottom; such anomalies may indicate groundwater influx into the lake. These areas will be used to locate future seepage meter and piezometers installations.
Using Fiber-Optic Distributed Temperature Sensing t o Assess Groundwater-Lake Exchange in an Acid Mine Lake in Eastern GermanyMark B. Hausner 1, Jan H. Fleckenstein 2, Christiane Neumann 2, and Scott W. Tyler 3
1. Graduate Program of Hydrologic Sciences, University of Nevada Reno, [email protected] · 2. Department of Hydrology, University of Bayreuth, Bayreuth, Germany · 3. Department of Geological Science and Engineering, University of Nevada Reno, Reno, Nevada
BackgroundLake 77 is an acid mine lake in Eastern Germany where previous studies have found strong influences of groundwater inflow on biogeochemical processes at the lake-groundwater interface. In this study, we:
• Deploy a fiber-optic DTS cable laterally along the lake bottom and vertically in the lake substrate to continuously measure temperatures in these areas
• Use anomalies in the diurnal temperature wave at the sediment-water interface to identify likely points of groundwater influx to the lake
Methods
Using Temperature as a Groundwater Tracer
Field Deployment
AGU PosterOS51D-1284
Results and Discussion
after Stonestrom and Constantz, 2003
The high heat capacity of water makes temperature an excellent tool for examining the interactions between groundwater and surface water. Groundwater and surface water have distinct thermal signatures. While surface water shows a high-amplitude temperature cycle (in both annual and diurnal cycling), groundwater tends to be more constant and exhibits dampened temperature cycles on a daily and seasonal basis. These differences can be used to identify and quantify regions of groundwater-surface water interactions.
Anti-StokesStokes
shifts with temperature
Brillouinin frequency
Raman(Anti-Stokes)in amplitude
Rayleigh Scattering
BrillouinRaman(Stokes)
Frequency
Am
plitu
de/ I
nten
sity
Hatch, 2008
Fiber optic distributed temperature sensing (DTS) relies on the scattering of light in a glass fiber to measure temperatures at very high spatial and temporal resolutions along a fiber-optic cable. The ratio of the Raman spectra scattered components (the temperature-independent Stokes and temperature-dependent Anti-Stokes signals) and the two-way travel time from the instrument to the point of reflection and back are used to determine the temperature and the location of the point of scattering. Spatial resolutions up to every 2 meters and temporal resolution as fine as 15 seconds can be achieved with this technology.
Hatch, C.E., S. Tyler, T. Cluff, M. Hausner, W. Miller, E. Carroll-Moore, and J. Davison (2008), Using distributed temperature sensing to assess soil moisture in agricultural settings, Geological Society of America 2008 Fall Meeting, Houston, Texas.
Stonestrom, D.A. and J. Constantz, ed., (2003), Heat as a tool for studying the movement of groundwater near streams, USGS Circular 1260, USGS.
Tyler, S.W., J.S. Selker, M.B. Hausner, C.E. Hatch, T. Torgersen, and S.G. Schladow (2007), Environmental temperature sensing using Raman spectra DTS fiber optic methods, Water Resour. Res., in press.
Volze, N., C. Neumanne, and J. Fleckenstein (2008), Quantifying the spatial and temporal variability of groundwater – lake exchange.
Three fiber optic cables were deployed at the study site – one laterally along the sediment-water interface, and two vertical profilers. The lateral deployment utilized a loose-tube cable with teflon strength members and protective insulation, while the vertical deployments relied on delicate tight-buffered fibers encased in PVC insulation.
Volze et al., 2008
Lake 77, with the study area indicated by the gold box.
The daily amplitude of the temperature signal (calculated as the difference between the maximum and minimum daily mean temperatures at the lake bottom) is shown below for the length of the cable. Daily amplitude is affected by the depth of water and exposure to sunlight, as well as the potential influence of groundwater fluxes. Areas with localized groundwater influxes will have reduced amplitude when compared to other points of similar depth. Three amplitude phenomena are highlighted on the plots below.
Conclusions References• Fiber optic DTS is a feasible technology for use in identifying
spatially-scattered temperature anomalies that may be associated with groundwater influxes into a lake.
• Additional measurement methods will likely be required to quantify fluxes between surface waters and groundwaters
• Fiber-optic cable used in environmental monitoring must be robust and durable to survive the deployment and return reliable data.
Fiber-Optic Distributed Temperature Sensing (DTS)
• Lateral deployment: cable laid at the sediment-water interface along the lake bottom. 2 meter spatial resolution, 15 minute temporal resolution
• Two vertical deployments: fine fiber wrapped around a 2” PVC pipe and installed vertically in the lakebed sediments. 2.2 centimeter vertical resolution, 15 minute temporal resolution
The cables used on this site included:
Diurnal Lakebed Temperature Profile
Increasing Temperature
AfternoonDawn
Lake
Downward FluxUpward Flux
The highlighted points on the above plots show the following phenomena:
funding for this research was provided by the:
Bavaria California Technology Center (BaCaTeC)http://www.bacatec.de/
The fiber used in the vertical profilers was not robust enough to stand up to the rigors of the field. The laterally-deployed cable returned two days worth of data, presented below. However, peak temperature measurements were affected by an unknown source of interference. As a result, the data presented below will require further investigation.
200 300 400 500 600 700 800 9001
2
3
4
5
6
7
Distance Along Cable
Dai
ly T
empe
ratu
re A
mpl
itude
(C
)
Daily Temperature Amplitude
Western Array
East-West Transects
Northern Array
0 1 2 3 4 5 6 7
0
20
40
60
80
100
120
Daily Temperature Amplitude (C)
Wat
er D
epth
(cm
)
Temperature Amplitude vs. Depth
200 300 400 500 700 800 900
Daily Temperature Amplitudes
Am
plitu
de (
°C)
Dep
th o
f Wat
er (
cm)
Amplitude (°C)
Temperature Amplitude vs. DepthTemperature Amplitude and Water Depth
Amplitude (°C)1.6 6.8Scale (m)
600Distance along Cable (m)
The field work for this study was conducted in August, 2008. The groundwater flow data collected during this project is one component of a larger study examining the hydrological and geochemical processes at work in the entire mine complex.
C:\MBH\DTS Projects\Lake 77, Germany\lake77_1.bmp
•Gold Circle: A likely area of groundwater intrusion that requires further investigation.•Red Circle: a quick transition from deeper to shallow water, resulting in an isolated high amplitude point.•Magenta Circle: a shallow, high amplitude area likely affected by solar heating.
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