Thomas Kalbacher

Helmholtz Centre for Environmental Research | UFZ · Department of Environmental Informatics

Regional groundwater modelling can provide decision-makers and scientists with valuable information required for the sustainable use and protection of groundwater resources in the future. In order to assess and manage the impact of climate change on regional aquifer systems, numerical groundwater models are required which represent the subsurface s...

Introduction: Pressure on groundwater resources is increasing rapidly by population growth and climate change effects. Thus, it is urgent to quantify their availability and determine their dynamics at a global scale to assess the impacts of climate change or anthropogenically induced pressure, and to support water management strategies. In this con...

Geoscientific data analysis has to face some challenges regarding seamless data analysis chains, reuse of methods and tools, interdisciplinary approaches and digitalization. Computer science and data science offer concepts to face these challenges. We took the concepts of scientific workflows and component-based software engineering and adapted it...

Reliable data are the base of all scientific analyses, interpretations and conclusions. Evaluating data in a smart way speeds up the process of interpretation and conclusion and highlights where, when and how additionally acquired data in the field will support knowledge gain. An extended SMART monitoring concept is introduced which includes SMART...

The Digital Earth project aims at a strong interrelation between Data and Earth Science and a step-change in implementing data science methods within Earth science research. During the project, the progress of interdisciplinary collaboration and adoption of data science methods has been measured and assessed with the goal to trace the success of th...

Large‐scale and high‐resolution groundwater models are currently becoming increasingly important in order to clarify the extent to which climate trends and extreme weather affect the groundwater balance regionally. As a result, the parameterization of groundwater models is becoming more detailed and more complex, making conventional calibration met...

Large‐scale groundwater models are required to estimate groundwater availability and to inform water management strategies on the national scale. However, parameterization of large‐scale groundwater models covering areas of major river basins and more is challenging due to the lack of observational data and the mismatch between the scales of modeli...

We propose a framework for the 3D exploration of heterogeneous environmental data within a geographical region of interest. Based on Unity, the system can be built for a variety of platforms and works both on regular machines as well as in virtual reality environments, where it can be considered a basis for a virtual geographic environment. Focussi...

Planning an event-based monitoring campaign on the regional scale is challenging, e.g. the timing and location of monitoring visits can dramatically impact monitoring efficacy and depends on the optimal environmental conditions required by the measurement parameters and the overarching monitoring goal. Therefore we developed a generic campaign plan...

Recent discussions in many scientific disciplines stress the necessity of “FAIR” data. FAIR data, however, does not necessarily include information on data trustworthiness, where trustworthiness comprises reliability, validity and provenience/provenance. This opens up the risk of misinterpreting scientific data, even though all criteria of “FAIR” a...

OpenGeoSys (OGS) is a scientific open-source initiative for the numerical simulation of thermo-hydro-mechanical/chemical (THMC) processes in porous and fractured media. The basic concept of OGS consist on providing a flexible numerical framework, using primarily the Finite Element Method (FEM) for solving multi-field coupled processes with applicat...

First workflows to build up hydrogeological 3D Models from GIS data sets are ready.

First workflows to build up hydrogeological 3D Models from GIS data sets are ready.

A risk‐based decision‐making mechanism capable of accounting for uncertainty regarding local conditions is crucial to water resources management, regulation, and policy making. Despite the great potential of hydrogeological models in supporting water resources decisions, challenges remain due to the many sources of uncertainty as well as making and...

By its very nature, research into multi-physical processes occurring in porous and fractured media requires a collaborative approach. An interdisciplinary approach has led to the adoption of collaborative software development paradigms in this field relying on software for scientific computing as research infrastructures. The development of open-so...

Aerated treatment wetlands are an increasingly recognized nature-based technology for wastewater treatment that relies heavily on mechanical aeration. Although aeration-mediated oxygen transfer into the wastewater can be impeded by wastewater pollutants, little is known about the link between the volumetric oxygen mass transfer coefficient kLa and...

Despite recent developments in process-based modeling of treatment wetlands (TW), the dynamic response of horizontal flow (HF) aerated wetlands to interruptions of aeration has not yet been modeled. In this study, the dynamic response of organic carbon and nitrogen removal to interruptions of aeration in an HF aerated wetland was investigated using...

Links Release page on www.opengeosys.org 3 GitHub Release Zenodo Release Jenkins build

New processes A thermo-hydro-mechanical (THM) process, monolithic implementation for Newton non-linear solver. #2446 Other process’ changes Non-equilibrium initial state in the small deformation, HM, and TM processes. #2501, #2561, and #2544 A reactive transport process, integrated IPhreeqc Module 3.5.0 for reactive transport modeling. #2494, #251...

Mechanical aeration is commonly used to improve the overall treatment efficacy of constructed wetlands. However, the quantitative relationships of air flow rate (AFR), water temperature, field oxygen transfer and treatment performance have not been analyzed in detail until today. In this study, a reactive transport model based on dual–permeability...

Groundwater travel time distributions (TTDs) provide a robust description of the subsurface mixing behavior and hydrological response of a subsurface system. Lagrangian particle tracking is often used to derive the groundwater TTDs. The reliability of this approach is subjected to the uncertainty of external forcings, internal hydraulic properties,...

The overall objective of the project was the development of water management system solutions for a sustainable improvement of water quality in the city of Chaohu and in the Chao Lake. The Urban Water Resources Management (UWRM) concept is the innovative approach, which includes both efficient urban water management in urban and suburban areas, as...

In this chapter, the structure and content of the input files for setting up reactive transport models are described. First, OGS input file description will be presented (Sect. 4.1), and then, a short description of the PHREEQC input file will be followed (Sect. 4.2).

This tutorial provides the application of the coupling interface OGS#IPhreeqc (open-source scientific software) to model reactive mass transport processes in environmental subsurface systems. It contains general information regarding reactive transport modeling and step-by-step model set-up with OGS#IPhreeqc and related components such as GINA and...

Geological heterogeneity, i.e. the spatial variability of discrete hydrogeological units, is investigated in an aquifer analog of glacio-fluvial sediments to determine how such a geological structure can be simplified for characterization needs. The aquifer analog consists of ten hydrofacies whereas the scarcity of measurements in typical field stu...

Nitrate reduction reactions in groundwater systems are strongly influenced by various aquifer heterogeneity factors that affect the transport of chemical species, spatial distribution of redox reactive substances and, as a result, the overall nitrate reduction efficiency. In this study, we investigated the influence of physical and chemical aquifer...

This benchmark problem is based on the reactive transport example presented in Sect. 15.6 of benchmark book volume I (Kolditz et al. 2012c), which was originally described in van Breukelen et al. (2005).

The hillslope scale is an important transition between the field scale and the catchment scale. The water flow in the unsaturated zone of a hillslope can be highly dynamic, which can lead to dynamic changes of groundwater flow or stream outflow. Additionally, interactions among host rock formation, soil properties and recharge water from precipitat...

Nitrate reduction reactions, as one of the most important redox reactions in a subsurface system, are strongly influenced by various heterogeneity factors which influence transport of chemical species and spatial distribution of redox substances and consequently have an effect on overall nitrate reduction capacity. In this presented work, the influ...

The open-source scientific software packages OpenGeoSys and IPhreeqc have been coupled to set up and simulate thermo-hydro-mechanical-chemical coupled processes with simultaneous consideration of aqueous geochemical reactions faster and easier on high-performance computers. In combination with the elaborated and extendable chemical database of IPhr...

This technical paper presents an efficient and performance-oriented method to model reactive mass transport processes in environmental and geotechnical subsurface systems. The open source scientific software packages OpenGeoSys and IPhreeqc have been coupled, to combine their individual strengths and features to simulate thermo-hydro-mechanical-che...

Introduced by Richards [1], the Richards’ equation is used to mathematically describe water movement in the unsaturated zone. Theoretically, the equation is also a sort of simplification of the two-phase flow equations of water-air processes in porous media under the constant gas pressure condition.

Civilization and in particular agriculture worldwide depends on the availability of clean freshwater resources stored in the underlying soil and aquifer systems. Unfortunately, water quality is often deteriorating, which is e.g. due to the extensive use of fertilizers or pesticides in agriculture or infiltrating waste water from cities and industri...

Nitrate contamination in shallow groundwater is still one of the common problems in many countries. Because of its high solubility and anionic nature, nitrate can easily leach through soil and persist in groundwater for decades. High nitrate concentration has been suggested as a major cause of accelerated eutrophication, methemoglobinemia and gastr...

Worldwide, sustainable water resource management becomes an increasingly challenging task due to the growth of population and extensive applications of fertilizer in agriculture. Moreover, climate change causes further stresses to both water quantity and quality. Reactive transport modeling in the coupled soil-aquifer system is a viable approach to...

Reactive transport simulations within subsurface systems are an essential modeling approach to assess e.g. the impacts of different land use on water resources. Many fundamental coupling methods and interfaces have been developed and tested within OGS over the last years. Even the code has been successfully benchmarked, some applications and case s...

Two distinct MPI (Message Passing Interface) groups and relevant inter- and intra-communicators are created. The CPUs of the first group MPI_Group1 take part in the simulation of both domain decomposition related processes (flow, mass transport) and chemical reactions, while the second group MPI_Group2 only participate in the simulation of chemical...

The International Water Research Alliance Saxony (IWAS) is addressing the global challenges concerning water quality in the areas of drinking water and sanitation, agricultural irrigation and the quality of surface and ground waters, as well as developing specific ecosystem-relevant services to be implemented on an exemplary basis in selected model...

A general description of the mathematical and numerical formulations used in modern numerical reactive transport codes relevant for subsurface environmental simu-lations is presented. The formulations are followed by short descriptions of commonly used and available subsurface simulators that consider continuum representations of flow, transport, a...

Agricultural practices impact soils and the wider environment (groundwater, receiving water courses and ponds, etc.) with various feedback loops. For instance, groundwater extraction may increase infiltration rates and nitrate leaching from the plant root zone. To assess such inter-compartment feedbacks with a numerical model, the object-oriented m...

This poster presents an open-source framework designed to assist water scientists in the study of catchment hydraulic functions with associated chemical processes, e.g. contaminant degradation, plant nutrient turnover. The model successfully calculates the feedbacks between surface water, subsurface water and air in standard benchmarks. In specific...

This paper presents an inter-compartment boundary condition for the simulation of surface runoff, soil moisture, and soil air as a coupled system of partial differential equations. The boundary condition is based on a classic leakance approach to balance water between differently mobile regions such as the land surface and subsurface. Present work...

This work introduces the soil air system into integrated hydrology by simulating the flow processes and interactions of surface runoff, soil moisture and air in the shallow subsurface. The numerical model is formulated as a coupled system of partial differential equations for hydrostatic (diffusive wave) shallow flow and two-phase flow in a porous...

Sustainable water quality management requires a profound understanding of water fluxes (precipitation, run-off, recharge, etc.) and solute turnover such as retention, reaction, transformation, etc. at the catchment or landscape scale. The Water and Earth System Science competence cluster (WESS, http://www.wess.info/) aims at a holistic analysis of...

OpenGeoSys solves the balance equations for mass, momentum, and energy conservation in a coupled manner. The porous medium approach represents multi-phase, multi-component systems. A large variety of equations-of-state and constitutive laws allow for different environmental applications

State-of-the-art computational models used for integrated water resources management are rapidly developing instruments. Advances in computational mathematics have revolutionized the variety and the nature of the problems that can be addressed by environmental scientists and engineers. For each hydro-compartment, from precipitation and surface run-...

The idea of this paper is twofold. On one hand, we propose a general systematic for benchmarking of CO 2 modelling. On the other hand, we integrate material from the CLEAN project into this framework to demonstrate its applicability (Kühn et al. in Environ Earth Sci, this issue 2011). Benchmarks are an important instrument to gain a better understa...

In this paper we describe the OpenGeoSys (OGS) project, which is a scientific open-source initiative for numerical simulation of thermo-hydro-mechanical-chemical processes in porous media. The basic concept is to provide a flexible numerical framework (using primarily the Finite Element Method (FEM)) for solving multifield problems in porous and fr...

The paper presents a modeling strategy as well as simulation results of a designed conservative tracer test in the depleted Altensalzwedel natural gas reservoir in order to know the tracer concentration and breakthrough time at the production wells. Krypton is considered as a suitable tracer. The production wells are located in several hundred mete...

Benchmarking coupled surface-subsurface flow models becomes more important as they are increasingly used for operational purposes (e.g. in water management) and long-term analysis (e.g. in climate change research). For this reason we inter-compare the hydrogeological models HydroGeoSphere and OpenGeoSys and present results with emphasis on the para...

Surface runoff models employ the Richards' approach to reproduce streamflow generation mechanisms (e.g. Horton, Dunne, subsurface stormflow) in the nearsurface environment. By design, they implicitly assume that the air phase is infinitely mobile and at atmospheric pressure in the entire soil compartment. To relax this assumption and numerically st...

Numerical modeling of interacting flow and transport processes between different hydrological compartments, such as the atmosphere/land surface/vegetation/soil/groundwater systems, is essential for understanding the comprehensive processes, especially if quantity and quality of water resources are in acute danger, like e.g. in semi-arid areas and r...

Hydrological research projects for integrated water resources management such as the IWAS initiative often accumulate large amounts of heterogeneous data from different sources. Given the number of partners taking part in such projects, surveying and accessing the available data sets, as well as searching for a defined subset, becomes increasingly...

The upper parts of the ground usually belong to the vadose zone, i.e. the zone between land surface and the top of the upper aquifer. This zone is a transition section between the atmosphere, biosphere, lithosphere and hydrosphere and connects the neighboring compartments via air, water and solids including biomass and organic matter. The vadose zo...

In this paper we describe the OpenGeoSys (OGS) project, which is a scientific open-source initiative for numerical simulation of thermo-hydro-mechanicalchemical processes in porous media. The basic concept is to provide a flexible numerical framework (using primarily the Finite Element Method (FEM)) for solving multifield problems in porous and fra...

Water shortage and groundwater pollution have become two primary environmental concerns to Beijing since the 1990s. The local aquifers, as the dominant sources for domestic and agricultural water supply, are depleting due to groundwater abstraction and continuous drought in recent years with rapid urbanization and increasing water consumption. Ther...

As part of a project which deals with a large scale groundwater study aimed at simulating the available groundwater resources in the Upper Mega Aquifer system in the eastern part of Saudi Arabia, an interactive visualization has been created in order to show the simulation results, together with the original borehole data from which the input model...

Numerical modeling of interacting flow processes between roots and the soil is essential for understanding the influence of different root geometries and types on the hydrosystem. The coupling of two software tools enables the analysis of water uptake of plant communities, one modeling the water flow along a network of resistances from the bulk soi...

As part of a project which deals with a large scale groundwater study aimed at simulating the available groundwater resources in the Upper Mega Aquifer system in the eastern part of Saudi Arabia, an interactive visualization has been created in order to show the simulation results, together with the original borehole data from which the input model...

Benchmarking hydrological models becomes more important as they are increasingly used for operational purposes e.g. in water management and long-term analysis e.g. in climate change research. We verify and compare the simulation platforms HydroGeoSphere and OpenGeoSys regarding flow and solute transport in coupled surface-soil hydrosystems. The num...

Numerical modelling of interacting flow processes between roots and soil is essential for understanding the influence of different root geometries and types on the hydro-system. This technical contribution will describe the coupling of two software tools to enable the analysis of water uptake of plant communities, one modelling the water flow along...

Virtual Hydrologic Environment (VHE) is an integrated approach where two major data systems are included: integration of different types of GIS and water resources data, integration of data and modeling. The Unified Modeling Language (UML) facilitates the design of GIS based relational database model GeoHydro/DataBase(GH/DB) and is used to create a...

Numerical analysis of thermo-hydro-mechanical coupled finite element problems in fractured or porous media involves significant computational resources and parallel computing is a way to enable the use of the necessary computer power of SMP machines or clusters. An interdisciplinary collaboration is essential to port large scale and complex softwar...

Ongoing developments in geological and hydrogeological investigation techniques, especially direct-push methods, have led to an increase in the quality, density and spatial resolution of data available from such investigations. This has created new challenges in the development of numerical models in terms of accurately and efficiently translating...

Discrete fracture network simulations are computationally intensive and usually time-consuming to construct and configure. This paper presents a case study with techniques for building a 3D finite element model of an inhomogeneous fracture network for modelling flow and tracer transport, combining deterministic and stochastic information on fractur...

The implementation of numerical methods involving geometrical description of geosystems with the application of numerical meshes is of vital importance for investigation and modelling of complex, coupled, natural, or man-induced processes. Innovative application of CAD-Systems in combination with computer aided modeling of such systems provides a u...

A GIS based hydrosystem is used for groundwater modeling. The system takes advantage of GIS capabilities, such as image georeferencing, feature creation, data modification, and data thematic organization to assemble hydrogeological data with computer accuracy and a minimal risk of human error. Shape files from ArcGIS, like points, polylines and pol...