Theoretical analysis and considerations of the main parameters used to evaluate intrinsic karst groundwater vulnerability to surface pollution.

Karst aquifers are highly susceptible to surface pollution scenarios due to exokarst features allowing a fast infiltration regime, bypassing the unsaturated zone. Intrinsic vulnerability maps are a visual interpretation of different levels of vulnerability estimated from multiple arrays of natural characteristics of the aquifer. However, for karst aquifers, this type of analysis is affected by the high subjectivity and personal interpretations of some karst features from hydrological or geological points of view.

An approach for quantification of the heterogeneity of DNAPL source zone geometries.

Many studies have investigated the migration and entrapment processes of source zones from dense non-aqueous phase liquid (DNAPL) contamination under different conditions. However, the characterization of occupying area by source zone (or source shape) in water-saturated aquifers is still rudimentarily considered. In this study, we demonstrated this issue (1) by providing a brief review of existing approaches for source shape consideration, (2) by proposing an approach with simple shape parameters based on the non-uniformity of source widths, and (3) by providing exemplary applications of our proposed approach on shapes already published in previous research works.

An Approach for Selecting a Model for the Assessment of Potentially Contaminated Sites.

Assessment of potentially contaminated sites (PCS) can be expensive; hence, simple and less demanding methods and models are required. This work attempts to provide an approach that can aid in selecting the most appropriate model for the PCS. The developed method uses over 100 field site data to evaluate four test models (analytical/empirical) that provide the maximum plume length (L ), which is used as a principal model ranking quantity in this work.

Determining the impact of flow velocities on reactive processes associated with Enterococcus faecalis JH2-2.

This study focuses on the impact of infiltration rates on colloidal transport and reactive processes associated with Enterococcus faecalis JH2-2 using water-saturated sediment columns. The infiltration rates influence the physical transport of bacteria by controlling the mean flow velocity. This, in turn, impacts biological processes in pore water owing to the higher or lower residence time of the bacteria in the column.

Contamination Assessment and Site-Management Tool (CAST): A Browser-Based Tool for Site Assessment.

Groundwater dependency is increasing globally, while millions of potentially contaminated sites are yet to be characterized for contamination levels. In particular, groundwater contamination due to light nonaqueous phase liquids (LNAPLs) continues to be a global challenge. Mathematical approaches (i.

Biological and Physical Clogging in Infiltration Wells: Effects of Well Diameter and Gravel Pack.

Gravity-driven infiltration into the shallow subsurface via small-diameter wells (SDWs), i.e., wells with an inner diameter smaller than 7.

Reactive-transport modelling of Enterococcus faecalis JH2-2 passage through water saturated sediment columns.

The reuse of treated wastewater (e.g. for irrigation) is a common practice to combat water scarcity problems world-wide.

Influence of recharge rates on steady-state plume lengths.

A large number of potentially contaminated sites reported worldwide require cost- and time-effective assessment of the extent of contamination and the threats posed to the water resources. A significant risk assessment metric for these sites can be the determination of the maximum (i.e.

An Approximation of Inner Boundary Conditions for Wells Intersecting Highly Conductive Structures.

Inner boundary conditions describe the interaction of groundwater wells with the surrounding aquifer during pumping and are associated with well-skin damage that limits water production and water derived from wellbore storage. Pumping test evaluations of wells during immediate and early time flow require assignment of inner boundary conditions. Originally, these concepts were developed for vertical well screens, and later transferred to wellbores intersecting highly conductive structures, such as preferential flow zones in fractured and karstic systems.

Hydrogeochemical and mixing processes controlling groundwater chemistry in a wastewater irrigated agricultural system of India.

In many parts of the world, wastewater irrigation has become a common practice because of freshwater scarcity and to increase resource reuse efficiency. Wastewater irrigation has positive impacts on livelihoods and at the same time, it has adverse impacts related to environmental pollution. Hydrochemical processes and groundwater behaviour need to be analyzed for a thorough understanding of the geochemical evolution in the wastewater irrigated systems.

The fate of DNAPL contaminants in non-consolidated subsurface systems - Discussion on the relevance of effective source zone geometries for plume propagation.

Dense non-aqueous phase liquids, i.e., DNAPLs and the evolving contaminant plumes in aquifers provide significant potential to pose hazards affecting both environment and human health.

Collected Rain Water as Cost-Efficient Source for Aquifer Tracer Testing.

Locally collected precipitation water can be actively used as a groundwater tracer solution based on four inherent tracer signals: electrical conductivity, stable isotopic signatures of deuterium [δ H], oxygen-18 [δ O], and heat, which all may strongly differ from the corresponding background values in the tested groundwater. In hydrogeological practice, a tracer test is one of the most important methods for determining subsurface connections or field parameters, such as porosity, dispersivity, diffusion coefficient, groundwater flow velocity, or flow direction. A common problem is the choice of tracer and the corresponding permission by the appropriate authorities.

Spatio-temporal distribution and chemical characterization of groundwater quality of a wastewater irrigated system: A case study.

Wastewater irrigation is a common livelihood practice in many parts of the developing world. With the continuous irrigation supply, groundwater systems in these regions perceive adverse impacts due to inadequate infrastructure to treat the wastewater. The current study area, Musi River irrigation system, is one such case study located in the peri-urban Hyderabad of South India.

Description and verification of a novel flow and transport model for silicate-gel emplacement.

We present a novel approach for the numerical simulation of the gelation of silicate solutions under density-dependent flow conditions. The method utilizes an auxiliary, not density-dependent solute that is subject to a linear decay function to provide temporal information that is used to describe the viscosity change of the fluid. By comparing the modeling results to experimental data, we are able to simulate the behavior and the gelation process of the injected solute for three different compositions, including long-term stability of the gelated area, and non-gelation of low concentrations due to hydro-dynamic dispersion.

Model-based prediction of long-term leaching of contaminants from secondary materials in road constructions and noise protection dams.

In this study, contaminant leaching from three different secondary materials (demolition waste, municipal solid waste incineration ash, and blast furnace slag) to groundwater is assessed by numerical modeling. Reactive transport simulations for a noise protection dam and a road dam (a typical German autobahn), in which secondary materials are reused as base layers, were performed to predict the breakthrough of a conservative tracer (i.e.

Multitracer test approach to characterize reactive transport in karst aquifers.

A method to estimate reactive transport parameters as well as geometric conduit parameters from a multitracer test in a karst aquifer is provided. For this purpose, a calibration strategy was developed applying the two-region nonequilibrium model CXTFIT. The ambiguity of the model calibration was reduced by first calibrating the model with respect to conservative tracer breakthrough and later transferring conservative transport parameters to the reactive model calibration.

Karst spring responses examined by process-based modeling.

Ground water in karst terrains is highly vulnerable to contamination due to the rapid transport of contaminants through the highly conductive conduit system. For contamination risk assessment purposes, information about hydraulic and geometric characteristics of the conduits and their hydraulic interaction with the fissured porous rock is an important prerequisite. The relationship between aquifer characteristics and short-term responses to recharge events of both spring discharge and physicochemical parameters of the discharged water was examined using a process-based flow and transport model.

Process-based interpretation of tracer tests in carbonate aquifers.

A tracer test in a carbonate aquifer is analyzed using the method of moments and two analytical advection-dispersion models (ADMs) as well as a numerical model. The numerical model is a coupled continuum-pipe flow and transport model that accounts for two different flow components in karstified carbonate aquifers, i.e.

Modelling of diffusion-limited retardation of contaminants in hydraulically and lithologically nonuniform media.

A new reactive transport modelling approach and examples of its application are presented, dealing with the impact of sorption/desorption kinetics on the spreading of solutes, e.g. organic contaminants, in groundwater.