Twin Lake Tracer Tests: Setting, methodology, and hydraulic conductivity distribution

1988 ◽  
Vol 24 (10) ◽  
pp. 1585-1612 ◽  
Author(s):  
R. W. D. Killey ◽  
G. L. Moltyaner
2020 ◽  
Vol 28 (8) ◽  
pp. 2657-2674
Author(s):  
Markus Theel ◽  
Peter Huggenberger ◽  
Kai Zosseder

AbstractThe favorable overall conditions for the utilization of groundwater in fluvioglacial aquifers are impacted by significant heterogeneity in the hydraulic conductivity, which is related to small-scale facies changes. Knowledge of the spatial distribution of hydraulically relevant hydrofacies types (HF-types), derived by sedimentological analysis, helps to determine the hydraulic conductivity distribution and thus contribute to understanding the hydraulic dynamics in fluvioglacial aquifers. In particular, the HF-type “open framework gravel (OW)”, which occurs with the HF-type “bimodal gravel (BM)” in BM/OW couplings, has an intrinsically high hydraulic conductivity and significantly impacts hydrogeological challenges such as planning excavation-pit drainage or the prognosis of plumes. The present study investigates the properties and spatial occurrence of HF-types in fluvioglacial deposits at regional scale to derive spatial distribution trends of HF-types, by analyzing 12 gravel pits in the Munich gravel plain (southern Germany) as analogues for outwash plains. The results are compared to the reevaluation of 542 pumping tests. Analysis of the HF-types and the pumping test data shows similar small-scale heterogeneities of the hydraulic conductivity, superimposing large-scale trends. High-permeability BM/OW couples and their dependence on recognizable discharge types in the sedimentary deposits explain sharp-bounded small-scale heterogeneities in the hydraulic conductivity distribution from 9.1 × 10−3 to 2.2 × 10−4 m/s. It is also shown that high values of hydraulic conductivity can be interpolated on shorter distance compared to lower values. While the results of the HF-analysis can be transferred to other fluvioglacial settings (e.g. braided rivers), regional trends must be examined with respect to the surrounding topography.


2021 ◽  
Author(s):  
Claus Haslauer ◽  
Bo Xiao ◽  
András Bárdossy ◽  
Olaf Cirpka ◽  
Geoffrey Bohling

<div> <p><span>The incentive of this presentation is the age-old quest of stochastic hydrogeology: Are we able to better match observed long-tailed breakthrough curves by an improved description of the spatial dependence of saturated hydraulic conductivity (<em>K</em>)?</span></p> </div><div> <p><span> </span></p> </div><div> <p><span>This contribution considers two innovations: We include more information than usual by incorporating multiple types of observations at non-collocated locations (<em>data fusion</em>), and we extract more information than usual from the available measurements by analysing statistical properties that go further than typical second-order moments-based analyses (<em>non-Gaussian geostatistics</em>).</span></p> </div><div> <p><span> </span></p> </div><div> <p><span>The evaluation of these innovations in geostatistical simulation methodologies of spatially distributed fields of <em>K</em> is performed against real-world tracer-tests that were performed at the site of the <em>K</em> measurements. The hypothesis is that fields that contain the most information match the observed solute spreading best.</span></p> </div><div> <p><span> </span></p> </div><div> <p><span>The spatially distributed <em>K</em>- fields were geostatistically simulated using the multi-objective phase annealing (<em>PA</em>) method. To accelerate the asymmetry updating during the PA iterations, a Fourier transform based algorithm is integrated into the three-dimensional PA method. Multiple types of objective functions are included to match the value and/or the order of observations as well as the degree of the “non-Gausianness” (asymmetry). Additionally, “censored measurements” (e.g., high-K measurements above the sensitivity of the device that measures <em>K</em>) are considered.</span></p> </div><div> <p><span> </span></p> </div><div> <p><span>The MAcroDispersion Experiment (MADE) site is considered the holy grail of stochastic hydrogeology as among the well instrumented sites in the world, the variance of the hydraulic conductivity measurements at the MADE site is fairly large and detailed observations of solute spreading are available. In addition to the classic <em>K</em>-measurements obtained via 2611 flowmeter measurements, recently a large set of 31123 <em>K</em>‑measurements obtained via direct push injection logging (DPIL), are available, although not at the same locations where the flowmeter measurements were taken.</span></p> </div><div> <p><span> </span></p> </div><div> <p><span>The influence of including different types of information on the simulated spatially-distributed fields of <em>K</em> are evaluated by analyzing the ensemble spatial moments and the dispersivity of numerical conservative solute tracer tests performed using particle tracking. The improved dependence structure of <em>K</em> with all of the above knowledge contains more information than fields simulated by traditional geostatistical algorithms and expected as a more realistic realization of <em>K</em> at the MADE site and at many other sites where such data-fusion approaches are necessary.</span></p> </div>


2006 ◽  
Vol 18 (4) ◽  
pp. 487-495 ◽  
Author(s):  
Erica H. Hofstee ◽  
Dave I. Campbell ◽  
Megan R. Balks ◽  
Jackie Aislabie

Seabee Hook is a low lying gravel spit adjacent to Cape Hallett, northern Victoria Land, in the Ross Sea region of Antarctica and hosts an Adélie penguin (Pygoscelis adeliae) rookery. Dipwells were inserted to monitor changes in depth to, and volume of, groundwater and tracer tests were conducted to estimate aquifer hydraulic conductivity and groundwater velocity. During summer (November–February), meltwater forms a shallow, unconfined, aquifer perched on impermeable ice cemented soil. Groundwater extent and volume depends on the amount of snowfall as meltwater is primarily sourced from melting snow drifts. Groundwater velocity through the permeable gravel and sand was up to 7.8 m day−1, and hydraulic conductivities of 4.7 × 10−4 m s−1 to 3.7 × 10−5 m s−1 were measured. The presence of the penguin rookery, and the proximity of the sea, affects groundwater chemistry with elevated concentrations of salts (1205 mg L−1 sodium, 332 mg L−1 potassium) and nutrients (193 mg L−1 nitrate, 833 mg L−1 ammonia, 10 mg L−1 total phosphorus) compared with groundwater sourced away from the rookery, and with other terrestrial waters in Antarctica.


Geosciences ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 462
Author(s):  
Emilio Sánchez-León ◽  
Carsten Leven ◽  
Daniel Erdal ◽  
Olaf A. Cirpka

Pumping and tracer tests are site-investigation techniques frequently used to determine hydraulic conductivity. Tomographic test layouts, in which multiple tests with different combinations of injection and observation wells are performed, gain a better insight into spatial variability. While hydraulic tomography has repeatedly been applied in the field, tracer tomography lags behind. In a previous publication, we presented a synthetic study to investigate whether the ensemble Kalman Filter (EnKF) or the Kalman Ensemble Generator (KEG) performs better in inverting hydraulic- and tracer-tomographic data. In this work, we develop an experimental method for solute-tracer tomography using fluorescein as a conservative tracer. We performed hydraulic- and tracer-tomographic tests at the Lauswiesen site in Germany. We analyzed transient drawdown and concentration data with the EnKF and steady-state hydraulic heads and mean tracer arrival times with the KEG, obtaining more stable results with the KEG at lower computational costs. The spatial distribution of the estimated hydraulic conductivity field agreed with earlier descriptions of the aquifer at the site. This study narrows the gap between numerical studies and field applications for aquifer characterization at high resolution, showing the potential of combining ensemble-Kalman filter based methods with data collected from hydraulic and solute-tracer tomographic experiments.


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