Uncertainty assessment of quantifying spatially concentrated groundwater discharge to small streams by distributed temperature sensing

Lauer, Florian; Frede, Hans‐Georg

doi:10.1002/wrcr.20060

Cited by 6 publications

(17 citation statements)

References 24 publications

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“…[] discussed spatial‐scale‐induced errors, uncertainties and limitations of different techniques for estimating specific fluxes. There also exists detection noises of temperatures via the DTS technique [e.g., Lauer et al ., ; Rose et al ., ]. Although the temperature data in the EnKF and EnKS assimilation schemes in the current study are limited to separate points and vertical thermal exchanges in a control volume, the empirical thermal‐mixing model considers longitudinal heat transport and mixing processes.…”

Section: Discussionmentioning

confidence: 99%

Assimilation of temperature and hydraulic gradients for quantifying the spatial variability of streambed hydraulics

Xiang

Andrews

Liu

et al. 2016

Water Resources Research

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Understanding the spatial and temporal characteristics of water flux into or out of shallow aquifers is imperative for water resources management and eco-environmental conservation. In this study, the spatial variability in the vertical specific fluxes and hydraulic conductivities in a streambed were evaluated by integrating distributed temperature sensing (DTS) data and vertical hydraulic gradients into an ensemble Kalman filter (EnKF) and smoother (EnKS) and an empirical thermal-mixing model. The formulation of the EnKF/EnKS assimilation scheme is based on a discretized 1D advection-conduction equation of heat transfer in the streambed. We first systematically tested a synthetic case and performed quantitative and statistical analyses to evaluate the performance of the assimilation schemes. Then a real-world case was evaluated to calculate assimilated specific flux. An initial estimate of the spatial distributions of the vertical hydraulic gradients was obtained from an empirical thermal-mixing model under steady-state conditions using a constant vertical hydraulic conductivity. Then, this initial estimate was updated by repeatedly dividing the assimilated specific flux by estimates of the vertical hydraulic gradients to obtain a refined spatial distribution of vertical hydraulic gradients and vertical hydraulic conductivities.Our results indicate that optimal parameters can be derived with fewer iterations but greater simulation effort using the EnKS compared with the EnKF. For the field application in a stream segment of the Heihe River Basin in northwest China, the average vertical hydraulic conductivities in the streambed varied over three orders of magnitude (5 3 10 21 to 5 3 10 2 m/d). The specific fluxes ranged from near zero (q z < 60.05 m/d) to 61.0 m/d, while the vertical hydraulic gradients were within the range of 20.2 to 0.15 m/m. The highest and most variable fluxes occurred adjacent to a debris-dam and bridge pier. This phenomenon is very likely the result of heterogeneous streambed hydraulic characteristics in these areas. Our results have significant implications for hyporheic micro-habitats, fish spawning and other wildlife incubation, regional flow and hyporheic solute transport models in the Heihe River Basin, as well as in other similar hydrologic settings. (2016), Assimilation of temperature and hydraulic gradients for quantifying the spatial variability of streambed hydraulics, Water Resour. PUBLICATIONS measurements and differential stream gauging in series of synoptic surveys [Becker et al., 2004] can provide estimations over relatively large reaches. The most commonly used methods, seepage meters and piezometers can measure and/or estimate the seepage flux directly. Admittedly, these instruments only provide point-in-space measurements, but they can also provide localized estimates through averaging a relatively small representative area of a streambed.

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Section: Discussionmentioning

confidence: 99%

Assimilation of temperature and hydraulic gradients for quantifying the spatial variability of streambed hydraulics

Xiang

Andrews

Liu

et al. 2016

Water Resources Research

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“…noise levels and precision), but are also influenced by the physical conditions of the system, predominantly the velocity ratio and the temperature difference, but perhaps environmental conditions such as degree of mixing and the vertical velocity profile in the stream may play a larger role for field applications and raise the threshold for field conditions. In the study by Lauer et al (2013), a 2 % ratio of groundwater to surface water flow rates is identified as the limit in which the correct ratio can be extracted from temperature data for temperature differences from 1.2 to 4.2…”

Section: Discussionmentioning

confidence: 99%

“…• C. In contrast, the results of this study demonstrates that the limit of detection is at a ATR/STD of 0.02 which equals a 1 % velocity ratio (or 0.4 % flow ratio compared to 2 % flow ratio identified by Lauer and co-workers) for a 2 • C temperature difference. In the work of Lauer et al (2013) complete mixing of groundwater and surface water was assumed and used in the heatmass balance equation to estimate the groundwater discharge. Different assumptions may have contributed to the difference in the identified discharge detection limit in the two studies.…”

Section: Discussionmentioning

confidence: 99%

“…They assessed that the quality of results obtained with DTS were comparable to those obtained with geochemical tracers. For another stream-groundwater system (a natural first-order stream), Lauer et al (2013) investigated the limit of flow estimation from temperature data of DTS. They tested their system for ratios of groundwater to surface water flow of < 1 to 19 % and con-cluded that ratios above 2 % can be determined from the measured DTS temperature response using the energy balance equation.…”

Section: Introductionmentioning

confidence: 99%

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

Roshan

Young

Andersen

et al. 2014

Preprint

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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.

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“…The climate is temperate. Further information particularly about the hydrology of the catchment are described in Lauer et al (2013) andOrlowski et al (2014).…”

Section: Studienlandschaft Schwingbachtal: An Out-door Full Scale Leamentioning

confidence: 99%

Studienlandschaft Schwingbachtal: an out-door full-scale learning tool newly equipped with augmented reality

Aubert

Schnepel

Kraft

et al. 2015

Preprint

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Abstract. This paper addresses education and communication in hydrology and geosciences. Many approaches can be used, such as the well-known seminars, modelling exercises and practical field work but out-door learning in our discipline is a must, and this paper focuses on the recent development of a new out-door learning tool at the landscape scale. To facilitate improved teaching and hands-on experience, we designed the Studienlandschaft Schwingbachtal. Equipped with field instrumentation, education trails, and geocache, we now implemented an augmented reality App, adding virtual teaching objects on the real landscape. The App development is detailed, to serve as methodology for people wishing to implement such a tool. The resulting application, namely the Schwingbachtal App, is described as an example. We conclude that such an App is useful for communication and education purposes, making learning pleasant, and offering personalized options.

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Uncertainty assessment of quantifying spatially concentrated groundwater discharge to small streams by distributed temperature sensing

Cited by 6 publications

References 24 publications

Assimilation of temperature and hydraulic gradients for quantifying the spatial variability of streambed hydraulics

Assimilation of temperature and hydraulic gradients for quantifying the spatial variability of streambed hydraulics

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

Studienlandschaft Schwingbachtal: an out-door full-scale learning tool newly equipped with augmented reality

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