Transfer processes in the chalk critical zone – Multidisciplinary study of the undergound quarry of Saint Martin le Noeud

2020 ◽  
Author(s):  
Danièle Valdés ◽  
Ningxin Chen ◽  
Marc Dumont ◽  
Christelle Marlin ◽  
Hélène Blanchoud ◽  
...  
Keyword(s):  
Time Series ◽  
Water Table ◽  
Vadose Zone ◽  
Variable Thickness ◽  
Critical Zone ◽  
Geochemical Data ◽  
Clay Layer ◽  
Transfer Processes ◽  
Multidisciplinary Study ◽  
Saint Martin

<p>The Chalk aquifer is a crucial, vital resource for water supply in France, Belgium and England. However, since several decades, this resource is threatened by high anthropogenic pressures: inducing a degradation of the groundwater’s quality.</p><p>The aim of our multidisciplinary study is to understand the transfer processes of the water and associated elements - solutes and contaminants (nitrate, pesticides) - throughout the critical zone (CZ) of chalk from the topsoil to the water table.</p><p>This study is focused on the underground quarry of Saint Martin le Noeud which is located in the Upper Cretaceous chalk layer of the Paris Basin. A layer of clay-with-flints covers the chalk of the quarry with a variable thickness. At a depth from 16 to 30m, the quarry is about 1200 m long and 150 m wide, giving a direct access to different groundwater compartments: (1) the Chalk water table through a series of 16 underground lakes, and (2) the vadose zone thanks to infiltration water percolating at the ceiling of the quarry. The set-up of this site allows to study the behaviors of both compartments.</p><p>Surface geophysical measurements: electrical resistivity tomography  and electromagnetic induction  mapping, have allowed to describe precisely the structure of the critical zone: in particular the geometry of the clay layer which has a variable thickness from 0 to about 5m.</p><p>The hydrodynamic and the quality of the groundwaters of both compartments (vadose zone and Chalk water table) have been characterized in time and space: (1) time series of flow percolation, water level, electrical conductivity and temperature, (2) geochemical analyses (major elements, nitrate, pesticides). The hydrodynamic and geochemical properties of the groundwaters vary spatially along the quarry highlighting different transfer processes.</p><p>Time series analysis and geochemical data allow to estimate the transfer velocities of the water and the contaminants and to precise the biogeochemical reactions (degradation, adsorption/desorption, storage …) that occurs in the CZ. These processes vary spatially depending on the properties of the CZ. The precise description of the clay layer compared to the groundwater behaviors allows to better characterize the infiltration processes. (1) a thin layer of clay induces a “diffuse infiltration”, low velocities, and low degradation of the pesticides in the subsurface, (2) a thick layer of clay induces a perched groundwater in the near-surface, degradation processes, concentrated infiltration and higher velocities.</p>

scholarly journals Real-time monitoring of nitrate transport in the deep vadose zone under a crop field – implications for groundwater protection

2016 ◽  
Vol 20 (8) ◽  
pp. 3099-3108 ◽  
Author(s):  
Tuvia Turkeltaub ◽  
Daniel Kurtzman ◽  
Ofer Dahan
Keyword(s):  
Real Time ◽  
Water Table ◽  
Vadose Zone ◽  
Land Surface ◽  
Agricultural Land ◽  
Root Zone ◽  
Isotopic Signature ◽  
Nitrate Transport ◽  
Mass Migration ◽  
Crop Field

Abstract. Nitrate is considered the most common non-point pollutant in groundwater. It is often attributed to agricultural management, when excess application of nitrogen fertilizer leaches below the root zone and is eventually transported as nitrate through the unsaturated zone to the water table. A lag time of years to decades between processes occurring in the root zone and their final imprint on groundwater quality prevents proper decision-making on land use and groundwater-resource management. This study implemented the vadose-zone monitoring system (VMS) under a commercial crop field. Data obtained by the VMS for 6 years allowed, for the first time known to us, a unique detailed tracking of water percolation and nitrate migration from the surface through the entire vadose zone to the water table at 18.5 m depth. A nitrate concentration time series, which varied with time and depth, revealed – in real time – a major pulse of nitrate mass propagating down through the vadose zone from the root zone toward the water table. Analysis of stable nitrate isotopes indicated that manure is the prevalent source of nitrate in the deep vadose zone and that nitrogen transformation processes have little effect on nitrate isotopic signature. The total nitrogen mass calculations emphasized the nitrate mass migration towards the water table. Furthermore, the simulated pore-water velocity through analytical solution of the convection–dispersion equation shows that nitrate migration time from land surface to groundwater is relatively rapid, approximately 5.9 years. Ultimately, agricultural land uses, which are constrained to high nitrogen application rates and coarse soil texture, are prone to inducing substantial nitrate leaching.

Predicting preferential flow and water table fluctuations in karst systems using film-flow theory and source-responsive models

2021 ◽  
Author(s):  
Torsten Noffz ◽  
Jannes Kordilla ◽  
Alireza Kavousi ◽  
Thomas Reimann ◽  
Martin Sauter ◽  
...  
Keyword(s):  
Water Table ◽  
Vadose Zone ◽  
Water Resource Management ◽  
Preferential Flow ◽  
Film Flow ◽  
Dry Valleys ◽  
Diffuse Infiltration ◽  
Water Table Fluctuations ◽  
Aquifer Systems ◽  
Karst Systems

<p>The locally focused dissolution of the rock material (e.g., below dolines and dry valleys) in karst systems and in general percolating clusters of fractures in consolidated aquifer systems trigger the development of preferential flow paths in the vadose zone. Rainfall events may initiate rapid mass fluxes via macropores and fractures (e.g., as gravitationally-driven films) that lead to source-responsive water table fluctuations and comparably short residence times within the vadose zone. The degree of partitioning into a slow diffuse infiltration component and a rapid localized part depends, amongst others, on the hydraulic interaction of porous matrix and fracture domain as well as the geometrical characteristics of the fracture systems (e.g., persistence, connectivity) that are often difficult to obtain or unknown under most field conditions. Given their importance in water-resource management, specifically in arid and semi-arid regions (e.g., Mediterranean), it is desirable to recover such infiltration dynamics in porous-fractured systems with physically-based yet not overparameterized models. Here, we simulate water table fluctuations in a karst catchment in southwest Germany (Gallusquelle) using a source-responsive film flow model based on borehole and precipitation data. The model takes into account interfacial connectivity between slow and fast domain as well as phreatic zone discharge via classical recession analysis. This case study shows the potential importance of preferential flows while modeling water table responses in karst systems and recognizes the need for formulations other than those applied for a diffuse bulk fractured domain where infiltration patterns are assumed to be homogeneous without formation of infiltration instabilities along preferential pathways.</p>

Application of Kalman filter to reproduce displacement pattern along with the unknown soil properties of slow-moving landslides

2021 ◽  
Author(s):  
Mohit Mishra ◽  
Gildas Besançon ◽  
Guillaume Chambon ◽  
Laurent Baillet ◽  
Arnaud Watlet ◽  
...  
Keyword(s):  
Time Series ◽  
Kalman Filter ◽  
Water Table ◽  
Field Data ◽  
Friction Angle ◽  
Early Warning Systems ◽  
Economic Losses ◽  
Slide Block ◽  
Slow Moving ◽  
Parameter Values

<p><span>Landslides display heterogeneity in movement types and rates, ranging from creeping motion to catastrophic acceleration. In most of the catastrophic events, rocks, debris, or soil can travel at several tens of meters per year speed, causing significant cost in life losses, infrastructure, economy, and ecosystem of the region. In contrast, slow-moving landslides display typical velocities scaling from few centimeters to several meters per year. Although slow-moving landslides rarely claim life losses, they can still cause considerable damage to public and private infrastructure. Sometimes these slow, persistent landslides eventually lead to catastrophic acceleration, e.g., clayey landslides are prone to these transitions. Such events need to be detected by Early Warning Systems (EWS) in advance to take timely actions to reduce life and economic losses. Several approaches are proposed to forecast the time of failure; still, there is a need to improve prediction strategies and EWS’s. </span></p><p><span>Here we present state and parameter estimation for a simplified viscoplastic sliding model of a landslide using a Kalman filter approach, which is termed as an observer problem in control theory. The model under investigation is based on underlying mechanics (physics-based model) that portray a landslide behavior. In this model, a slide block is assumed to be placed on an inclined surface, where landslide (slide block) motion is regulated by basal pore fluid pressure and opposed by sliding resistance governed by friction, cohesion, and viscosity. This model is described by an Ordinary Differential Equation (ODE) with displacement as a state and landslide material and geometrical properties as parameters. In this approach, known parameter values (landslide geometrical parameters and some material properties) and water table height time-series are provided as input. Finally, two illustrative examples validate the presented approach: i) a synthetic case study and ii) Hollin hill landslide (Uhlemann et al., 2016) field data. </span></p><p><span>In both examples, displacement, friction angle, and viscosity are well estimated from known parameter values, water table height time-series, and displacement measurements. In the simulation results for the Hollin Hill field data, it is observed that friction angle almost remains constant while viscosity varies significantly through time.</span></p><p> </p><p><span>Uhlemann, S., Smith, A., Chambers, J., Dixon, N., Dijkstra, T., Haslam, E., Meldrum P., Merritt, A., Gunn, D., and Mackay, J., (2016). Assessment of ground-based monitoring techniques applied to landslide investigations. </span><em><span>Geomorphology</span></em><span>, 253, 438-451. doi:10.1016/j.geomorph.2015.10.027.</span></p>

Monitoring of water table dynamics in peatlands with OPTRAM: Towards globally applicable algorithms in Google Earth Engine using Landsat and Sentinel-2

2021 ◽  
Author(s):  
Iuliia Burdun ◽  
Michel Bechtold ◽  
Viacheslav Komisarenko ◽  
Annalea Lohila ◽  
Elyn Humphreys ◽  
...  
Keyword(s):  
Time Series ◽  
Water Table ◽  
Input Data ◽  
Short Wave ◽  
Google Earth ◽  
Google Earth Engine ◽  
Short Wave Infrared ◽  
Northern Peatlands ◽  
Sentinel 2

<p>Fluctuations of water table depth (WTD) affect many processes in peatlands, such as vegetation development and emissions of greenhouse gases. Here, we present the OPtical TRApezoid Model (OPTRAM) as a new method for satellite-based monitoring of the temporal variation of WTD in peatlands. OPTRAM is based on the response of short-wave infrared reflectance to the vegetation water status. For five northern peatlands with long-term in-situ WTD records, and with diverse vegetation cover and hydrological regimes, we generate a suite of OPTRAM index time series using (a) different procedures to parametrise OPTRAM (peatland-specific manual vs. globally applicable automatic parametrisation in Google Earth Engine), and (b) different satellite input data (Landsat vs. Sentinel-2). The results based on the manual parametrisation of OPTRAM indicate a high correlation with in-situ WTD time-series for pixels with most suitable vegetation for OPTRAM application (mean Pearson correlation of 0.7 across sites), and we will present the performance differences when moving from a manual to an automatic procedure. Furthermore, for the overlap period of Landsat and Sentinel-2, which have different ranges and widths of short-wave infrared bands used for OPTRAM calculation, the impact of the satellite input data to OPTRAM will be analysed. Eventually, the challenge of merging different satellite missions in the derivation of OPTRAM time series will be explored as an important step towards a global application of OPTRAM for the monitoring of WTD dynamics in northern peatlands.</p>

Predicting water table depths in space and time using a regionalised time series model

Geoderma ◽  
2001 ◽  
Vol 103 (1-2) ◽  
pp. 51-77 ◽  
Author(s):  
Martin Knotters ◽  
Marc F.P. Bierkens
Keyword(s):  
Time Series ◽  
Water Table ◽  
Time Series Model ◽  
Space And Time

Correlation between the Fluctuations in Worldwide Seismicity and in Atmospheric Carbon Pollution

Sci ◽  
2018 ◽  
Vol 1 (1) ◽  
pp. 2
Author(s):  
Alberto Carpinteri ◽  
Gianni Niccolini
Keyword(s):  
Growth Rate ◽  
Time Series ◽  
Seismic Activity ◽  
Active Faults ◽  
Earth’S Crust ◽  
Atmospheric Co2 ◽  
Geochemical Evolution ◽  
Geochemical Data ◽  
Anthropogenic Emissions ◽  
Earth's Crust

The crucial stages in the geochemical evolution of the Earth’s crust, ocean, and atmosphere could be explained by the assumed low-energy nuclear reactions (LENR) that are triggered by seismic activity. LENR result in the fission of medium-weight elements accompanied by neutron emissions, involving Fe and Ni as starting elements, and C, N, O as resultants. Geochemical data and experimental evidences support the LENR hypothesis. The time series analysis highlighted significant correlation between the atmospheric CO2 growth rate and the global seismic-moment release rate, whereas the trending behavior was in response to the anthropogenic emissions. The fluctuations in the atmospheric CO2 growth rate time series were inexplicable in terms of anthropogenic emissions, but could be explained by the cycles of worldwide seismicity, which massively trigger LENR in the Earth’s crust. In this framework, LENR from active faults must be considered as a relevant cause of carbon formation and degassing of freshly-formed CO2 during seismic activity.

Evaluating the Impact of Nonisothermal Flow on Vadose Zone Processes in Presence of a Water Table

Soil Science ◽  
2014 ◽  
Vol 179 (2) ◽  
pp. 57-67 ◽  
Author(s):  
Jiangbo Han ◽  
Zhifang Zhou ◽  
Zhimin Fu ◽  
Jinguo Wang
Keyword(s):  
Water Table ◽  
Vadose Zone ◽  
Nonisothermal Flow ◽  
The Impact

scholarly journals Self-potential investigations of a gravel bar in a restored river corridor

2011 ◽  
Vol 15 (3) ◽  
pp. 729-742 ◽  
Author(s):  
N. Linde ◽  
J. Doetsch ◽  
D. Jougnot ◽  
O. Genoni ◽  
Y. Dürst ◽  
...  
Keyword(s):  
Water Table ◽  
Vadose Zone ◽  
Time Varying ◽  
Concentration Gradients ◽  
Electrode Potentials ◽  
Source Contributions ◽  
Influence Of Water ◽  
Potential Mapping ◽  
Gravel Bar ◽  
Self Potential

Abstract. Self-potentials (SP) are sensitive to water fluxes and concentration gradients in both saturated and unsaturated geological media, but quantitative interpretations of SP field data may often be hindered by the superposition of different source contributions and time-varying electrode potentials. Self-potential mapping and close to two months of SP monitoring on a gravel bar were performed to investigate the origins of SP signals at a restored river section of the Thur River in northeastern Switzerland. The SP mapping and subsequent inversion of the data indicate that the SP sources are mainly located in the upper few meters in regions of soil cover rather than bare gravel. Wavelet analyses of the time-series indicate a strong, but non-linear influence of water table and water content variations, as well as rainfall intensity on the recorded SP signals. Modeling of the SP response with respect to an increase in the water table elevation and precipitation indicate that the distribution of soil properties in the vadose zone has a very strong influence. We conclude that the observed SP responses on the gravel bar are more complicated than previously proposed semi-empiric relationships between SP signals and hydraulic head or the thickness of the vadose zone. We suggest that future SP monitoring in restored river corridors should either focus on quantifying vadose zone processes by installing vertical profiles of closely spaced SP electrodes or by installing the electrodes within the river to avoid signals arising from vadose zone processes and time-varying electrochemical conditions in the vicinity of the electrodes.

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