scholarly journals Modelling Water Dynamics, Transport Processes and Biogeochemical Reactions in Soil Vadose Zone

10.5772/63496 ◽  
2016 ◽  
Author(s):  
Vilim Filipović ◽  
Gabrijel Ondrašek ◽  
Lana Filipović
Keyword(s):  
Vadose Zone ◽  
Transport Processes ◽  
Water Dynamics

scholarly journals A vadose zone Transport Processes Investigation within the glacial till at the Fernald Environmental Management Project.

2007 ◽  
Author(s):  
J. Schwing ◽  
Craig Senninger Roepke ◽  
James Robert Brainard ◽  
Robert John, Jr. Glass ◽  
Michael J. A. Mann ◽  
...  
Keyword(s):  
Environmental Management ◽  
Vadose Zone ◽  
Transport Processes ◽  
Glacial Till ◽  
Management Project

Characterization of hydraulic properties in the upper vadose zone for two aquifers in Slovenia

2021 ◽  
Author(s):  
Vesna Zupanc ◽  
Matjaž Glavan ◽  
Miha Curk ◽  
Urša Pečan ◽  
Michael Stockinger ◽  
...  
Keyword(s):  
Stable Isotopes ◽  
Soil Water ◽  
Water Flow ◽  
Vadose Zone ◽  
Hydraulic Properties ◽  
Isotope Composition ◽  
Transport Processes ◽  
Precipitation Event ◽  
Water Fluxes ◽  
Flow And Transport

<p>Environmental tracers, present in the environment and provided by nature, provide integrative information about both water flow and transport. For studying water flow and solute transport, the hydrogen and oxygen isotopes are of special interest, as their ratios provide a tracer signal with every precipitation event and are seasonally distributed. In order to follow the seasonal distribution of stable isotopes in the soil water and use this information for identifying hydrological processes and hydraulic properties, soil was sampled three times in three profiles, two on Krško polje aquifer in SE Slovenia and one on Ljubljansko polje in central Slovenia. Isotope composition of soil water was measured with the water-vapor-equilibration method. Based on the isotope composition of soil water integrative information about water flow and transport processes with time and depth below ground were assessed. Porewater isotopes were in similar range as precipitation for all three profiles.  Variable isotope ratios in the upper 60 cm for the different sampling times indicated dynamic water fluxes in this upper part of the vadose zone. Results also showed more evaporation at one sampling location, Brege. The information from stable isotopes will be of importance for further analyzing the water fluxes in the vadose zone of the study sties. <br>This research was financed by the ARRS BIAT 20-21-32 and IAEA CRP 1.50.18 Multiple isotope fingerprints to identify sources and transport of agro-contaminants.  </p>

Vadose Zone, Part I : Characterization and Flow Processes

2003 ◽  
Author(s):  
Yoram Rubin
Keyword(s):  
Porous Media ◽  
Water Flow ◽  
Governing Equation ◽  
Vadose Zone ◽  
Stochastic Analysis ◽  
Transport Processes ◽  
Richards Equation ◽  
Saturated Porous Media ◽  
Flow And Transport ◽  
Flow Processes

Many of the principles guiding stochastic analysis of flow and transport processes in the vadose zone are those which we also employ in the saturated zone, and which we have explored in earlier chapters. However, there are important considerations and simplifications to be made, given the nature of the flow and of the governing equations, which we explore here and in chapter 12. The governing equation for water flow in variably saturated porous media at the smallest scale where Darcy’s law is applicable (i.e., no need for upscaling of parameters) is Richards’ equation (cf. Yeh, 1998)

scholarly journals Numerical Modeling on Fate and Transport of Pollutants in the Vadose Zone

2020 ◽  
Vol 2 (1) ◽  
pp. 34 ◽  
Author(s):  
Giacomo Viccione ◽  
Maria Grazia Stoppiello ◽  
Silvia Lauria ◽  
Leonardo Cascini
Keyword(s):  
Vadose Zone ◽  
Contaminated Soils ◽  
Fate And Transport ◽  
Transport Processes ◽  
Saturated Soils ◽  
Saturated Porous Media ◽  
Campania Region ◽  
Partially Saturated ◽  
Partially Saturated Soils ◽  
Method Approach

Soil contamination is an issue of paramount importance to assess human health (HHRA) as well as ecological (ERA) risk assessment. To analyze risk scenarios related to contaminated soils, the identification of sources, either of primary or secondary type, as well as the assessment of propagation and fate processes is needed. Although many studies refer to the transport of pollutants in fully saturated porous media, little efforts have been made concerning the case of partially saturated soils so far. The matter is of interest as the contamination in the fully saturated region may take place as a result of the percolation in the vadose zone. Governing equations ruling fate and transport processes in partially saturated soils are here solved numerically by means of a finite element method approach. Richards equations are adopted to describe flow dynamics through the hydraulic conductivity coefficient Ks, while contaminant fate is mainly described by the sorption coefficient Kp. As for the boundary conditions, we consider a local and continuous spill of contaminant at the upper ground of variable thickness. Precipitations are given as step functions whose intensity is derived by considering pluviometric data at the station of Gròmola, Campania Region, Italy. Benzene and tetrachloroethylene (PCE) are taken into account. A comparative analysis is carried out for permeability Ks and distribution Kd coefficients in the range [10−6, 10−4] m/s and [10−5, 10−3] m3/kg. Results are then compared and discussed.

Integrated Systems-Based Approach to Monitoring Environmental Remediation

2013 ◽  
Author(s):  
Michael J. Truex ◽  
Amoret L. Bunn ◽  
Mart Oostrom ◽  
K. C. Carroll ◽  
Dawn M. Wellman
Keyword(s):  
Surface Water ◽  
Vadose Zone ◽  
Environmental Remediation ◽  
Unsaturated Flow ◽  
Transport Processes ◽  
Department Of Energy ◽  
Integrated Systems ◽  
Monitoring Design ◽  
Contaminant Flux

The U.S. Department of Energy is responsible for risk reduction and cleanup of its nuclear weapons complex. Remediation strategies for some of the contamination may include techniques that mitigate risk, but leave contaminants in place. Monitoring to verify remedy performance and long-term mitigation of risk is key to implementing these strategies and can be a large portion of the total cost of remedy implementation. Especially in these situations, there is a need for innovative monitoring approaches that move away from the cost- and labor-intensive point-source monitoring. In this paper, alternative approaches for monitoring are presented for vadose zone, groundwater, groundwater/surface water interface, and surface water. To illustrate integrated, systems-based monitoring, this paper focuses on vadose zone contaminant remediation to mitigate impact to groundwater. In this context, vadose zone contamination is a source, or potential source, to groundwater plumes. The monitoring design uses a systems-based approach focused on developing a conceptual site model that highlights key features that control contaminant flux to groundwater. These features are derived considering the unsaturated flow and contaminant transport processes in the vadose zone and the nature of the waste discharge. Diagnostic properties and/or parameters related to both short- and long-term contaminant flux to groundwater can be identified and targeted for monitoring. The resolution of monitoring data needed to correspond to a functionally useful indicator of flux to groundwater can be estimated using quantitative analyses and the associated unsaturated flow properties relevant to the targeted site and vadose zone features. This monitoring design approach follows the process of developing a quantitative conceptual model suitable for supporting projections of future flux to groundwater. Support for such projections is important because it is likely that, in many cases, remediation decisions for the vadose zone will need to be made based all or in part on projected impacts to groundwater, and monitoring will then be applied to verify that remedy goals are being met.

scholarly journals A Decentralized Framework for Parameter and State Estimation of Infiltration Processes

Mathematics ◽  
2020 ◽  
Vol 8 (5) ◽  
pp. 681
Author(s):  
Song Bo ◽  
Jinfeng Liu
Keyword(s):  
Parameter Estimation ◽  
State Estimation ◽  
Vadose Zone ◽  
Three Dimensional ◽  
Water Dynamics ◽  
Richards Equation ◽  
Soil Water Dynamics ◽  
Decentralized Estimation ◽  
Gravitational Forces ◽  
Estimation Scheme

The Richards’ equation is widely used in the modeling soil water dynamics driven by the capillary and gravitational forces in the vadose zone. Its state and parameter estimation based on field soil moisture measurements is important and challenging for field applications of the Richards’ equation. In this work, we consider simultaneous state and parameter estimation of systems described by the three dimensional Richards’ equation with multiple types of soil. Based on a study on the interaction between subsystems, we propose to use decentralized estimation schemes to reduce the complexity of the estimation problem. Guidelines for subsystem decomposition are discussed and a decentralized estimation scheme developed in the framework of moving horizon state estimation is proposed. Extensive simulation results are presented to show the performance of the proposed decentralized approach.

Dynamic Characteristics of Polymer Electrolyte Fuel Cell and Hydrogen Tank

2010 ◽  
Author(s):  
Yun Wang
Keyword(s):  
Fuel Cell ◽  
Polymer Electrolyte ◽  
Dynamic Characteristics ◽  
Dynamic Models ◽  
Reaction Rates ◽  
Transport Processes ◽  
Water Dynamics ◽  
Polymer Electrolyte Fuel Cell ◽  
Limiting Factors ◽  
Electrochemical Double Layer

In this paper, we develop 3D dynamic models for polymer electrolyte fuel cells (PEFCs) and hydrogen tanks, respectively. The PEFC model considers the key components of a single PEFC and couples the various mechanisms that govern fuel cell transient including the electrochemical double-layer behavior, species transport, heat transfer, liquid water dynamics, and membrane water uptake. The hydrogen tank model includes a 3D description of the hydrogen discharging kinetics coupled with mass/heat transport in a LaNi5–based hydrogen tank. Efforts are made to discuss the dynamic characteristics of the PEFC and hydrogen tank together with the possible coupling of the two systems. Local electrochemical and hydride reaction rates, transport processes and associated limiting factors are investigated.

scholarly journals Modeling subsurface transport in extensive glaciofluvial and littoral sediments to remediate a municipal drinking water aquifer

2011 ◽  
Vol 8 (1) ◽  
pp. 1729-1764
Author(s):  
M. Bergvall ◽  
H. Grip ◽  
J. Sjöström ◽  
H. Laudon
Keyword(s):  
Drinking Water ◽  
Hydraulic Conductivity ◽  
Contaminant Transport ◽  
Vadose Zone ◽  
Transport Processes ◽  
Zone Model ◽  
Macropore Flow ◽  
Subsurface Transport ◽  
Littoral Sediments ◽  
Sandy Aquifers

Abstract. Few studies have been carried out that cover the entire transport process of pesticides, from application at the soil surface, through subsurface transport, to contamination of drinking water in esker aquifers. In formerly glaciated areas, such as Scandinavia, many of the most important groundwater resources are situated in glaciofluvial eskers. The purpose of the present study was to model and identify significant processes that govern subsurface transport of pesticides in extensive glaciofluvial and littoral sediments. To simulate the transport processes, we coupled a vadose zone model at the point scale to a regional groundwater flow model. The model was applied to a municipal drinking-water aquifer, contaminated with the pesticide-metabolite BAM (2,6-dichlorobenzoamide). A sensitivity analysis revealed that hydraulic conductivity and infiltration rate accounted for almost half of the model uncertainty. For a ten-meter-deep vadose zone of coarse texture, macropore flow was found to be of minor importance for contaminant transport. The calibrated model was applied to optimize the location of extraction wells for remediation, which were used to verify the predictive modeling. Running a worst-case scenario, the model showed that the establishment of two remediation wells would clean the aquifer in four years, compared to nine years without them. Further development of the model would require additional field measurements to assess the importance of macropore flow in deep, sandy aquifers. We also suggest that future research should focus on characterization of the variability of hydraulic conductivity and its effect on contaminant transport in eskers.

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