Research Center of Post-Mining

The question of how sustainable digitalisation can be achieved in post-mining was the focus of the symposium “Nachbergbauzeit NRW 2025 – Digitalisation meets tradition” held on 20th March 2025 at the Student Centre of the TH Georg Agricola University (THGA) in Bochum/Germany (Figure 1). Around 250 participants were able to experience in a variety of presentations and direct exchanges how much and what is already technically possible and successfully in use. The post-mining era in North Rhine-Westphalia thus built a thematic bridge from the traditional and historically immensely influential mining industry to the future and to state-of-the-art digital technologies.

Organised by the Research Center of Post-Mining (FZN) and the Department of Mining and Energy of the Arnsberg District Government, the event offered a nationally and internationally unique platform to show how digitalisation and traditional methods work together to sustainably master the challenges of post-mining.

The open and technically diverse structure of the post-mining era in North Rhine-Westphalia was addressed right at the start of the conference. In his welcome address, Prof. Christian Melchers, head of the FZN, aptly stated in line with the conference motto: “We have a treasure in the Ruhr region. And it is no longer hard coal. It is data.” Prof. ­Melchers not only emphasised the high value of geodata and the opportunities its digitalisation offers us, but also ventured a positive regional outlook for the coming decades: “The Ruhr region has the opportunity to become the greenest industrial region in the world!”

Post-mining is more than a regional issue – it is a project for the future with global relevance. Prof. Susanne Lengyel, President of the THGA, made this unmistakably clear. Her focus is on the young professionals who will help shape this change. “Together with our students and future graduates, we want to tackle the tasks that post-mining in particular brings with it,” emphasised Lengyel. For her, one thing is certain: cutting-edge research alone is not enough. We need people who are willing to take responsibility and break new ground. “The demand for raw materials is growing worldwide. We need to deal with this in a sustainable and responsible manner. These are all important issues that will occupy us today – and in the future.”

Heinrich Böckelühr, District President of the Arnsberg District Government, followed with a brief insight into the historical dimension of mining, the development of post-mining in North Rhine-Westphalia and the resulting challenges. He emphasised the importance of the Post-Mining Period in North Rhine-Westphalia, which is now taking place for the eighth time, describing it as a “genuine traditional event”. Heinrich Böckelühr also pointed out the enormous opportunities offered by digital technologies, e. g. in hazard prevention. According to the District President, the further digitalisation of the mining authority is indispensable and remains a key priority.

Bärbel Bergerhoff-Wodopia, member of the Executive Board of the RAG-Stiftung, spoke in her speech about sustainable financing and coping with perpetual obligations after the end of German coal mining. She particularly highlighted the FZN’s path to becoming a transformation centre for georesources and ecology (TGÖ). This development is a decisive step towards linking science, transfer and innovation more closely and providing forward-looking impetus for the sustainable use of georesources. Bergerhoff-Wodopia: “We are committed to supporting and accompanying the TGÖ on its journey, because we are certain that knowledge creates the basis for shaping a sustainable and liveable future!”

North Rhine-Westphalia, once an important mining region, has long since developed into a post-mining region. Today, the region uses its extensive experience and innovative knowledge to record and manage the traces of intensive raw material extraction. The symposium impressively demonstrated how historical legacy data and modern geodata can be combined to promote the sustainable management of post-mining landscapes.

The use of drones in post-mining, 3D modelling, improvements in digital maps for risk management, automation in geomonitoring, digitised water management, the use of AI and open data systems: the speakers were able to shed light on post-mining from a variety of topics and perspectives, visualise science in their presentations and explore potential.

The combination of lectures, discussions and networking opportunities, as well as the multi-perspective approach to the topic, once again proved to be a great asset to the eighth Post-Mining Period, as Prof. Melchers noted: “The Nachbergbauzeit NRW 2025 was a complete success. The concept has once again proven its worth. Comprehensive content, interesting presentations and great encounters already have me looking forward to the next Nachbergbauzeit NRW 2027.” (THGA/Si.)

North Rhine-Westphalia is a post-mining state: intensive raw material mining has left its mark especially in the Ruhr region and the Rhenish mining area. “When mining goes, what remains are challenges such as ground movements, large opencast mining lakes, disused sites of industrial culture or the so-called eternity tasks. At the same time, however, there are also many opportunities to reshape the region,” says Prof. Christian Melchers, head of the Research Center of Post-Mining (FZN) at TH Georg Agricola University (THGA), Bochum/Germany. How to deal responsibly with the legacy of mining was the focus of the specialist conference “NACHBergbauzeit in NRW” on 30th March 2023 at the THGA (Figure 1). Under the title “Geomonitoring – on water, on land and from the air”, around 300 experts came together in Bochum to exchange innovative methods.

Because when it comes to monitoring mining impacts, a lot of high-tech comes into play: from deep-sea probes underground to special drones in the air to satellites that can make ground movements or changes in the water balance and vegetation visible. “In this way, we are also making an important contribution to better understanding climate change in detail and to sensibly designing the so-called “blue-green infrastructure” – with knowledge from post-mining,” says Prof. Melchers. In the lecture programme, the speakers addressed which monitoring methods are best suited and how they can be combined in a meaningful way.

Bärbel Bergerhoff-Wodopia, member of the board of the RAG-Stiftung and chairwoman of the THGA’s university council, addressed the students in the hall in particular in her welcoming speech: “I am particularly pleased about your participation in the conference. Your interest in the topic of post-mining is for us as the RAG-Stiftung, but also for me personally, an incentive and motivation for the many years of promotion and support of the THGA and the FZN. We will continue to need well-trained experts for the topics we are discussing at today’s conference. The fact that you have chosen to study engineering shows that you want to help shape a new, green future. When it comes to the sustainable use of geo-resources and water management in former mining regions, know-how from post-mining is immensely important and will also be in great demand in the future.”

“However, we do not only want to reach experts with our joint series of events. We have the declared goal of informing politicians, administrators and the public about issues related to post-mining in North Rhine-Westphalia and to actively involve them in ongoing discussion processes,” says Andreas Welz, Head of the Mining and Energy Department in NRW of the Arnsberg District Government, when welcoming the participants. As the competent mining authority, the Arnsberg district government is responsible for a large number of mining consequences and takes care of risk management in affected areas – in NRW alone, more than half of all municipalities have to deal with the legacy of mining.

Ralf Groß-Holtick from the city of Gronau presented a special municipal project in which many citizens were also involved: The city planning officer presented the results from the research cooperation “Monitoring Epe”, in which the FZN, the city of Gronau and the local citizens’ initiative, among others, have worked closely together over the past two years. Their common goal: the establishment of long-term and accurate monitoring in the geologically special region around Gronau.

“Salt has been mined here intensively for almost 50 years. In the process, large cavities, the so-called caverns, have been created underground,” explains Prof. Tobias Rudolph from FZN. In the meantime, natural gas, crude oil or helium is stored in most of them. Right next door is a moorland, the Amtsvenn. “This special location leads to ground movements and also repeatedly to tensions – not only in the geological structures themselves, but also between the residents, the city and the various operating companies.” The research cooperation has now provided more transparency between science and society and is to be continued in the coming years. An enduring challenge is the communication of scientific results. Especially in an environment that is often emotional due to personal involvement.

For the eighth time, the Arnsberg District Government, Department of Mining and Energy in NRW and the FZN of the THGA jointly organised the conference “NACHBergbauzeit in NRW”. The next event in the series will take place in March 2025. (THGA/Si.)

Drone pilot Bodo Bernsdorf sees the world through different eyes. When he lets his special copter soar high above the grounds of the Zollverein coking plant in Essen/Germany, he not only encounters the chimneys and pipelines at flying height – he also finds damaged areas that are not even visible to the naked eye (Figure 1). The drone’s high-resolution images reveal how the industrial monument is really doing and where remediation is needed. That is at least the theoretical approach. Bernsdorf and his team from the Research Center of Post-Mining (FZN) at the TH Georg Agricola University (THGA), Bochum/Germany, want to detect material damage without leaving any traces themselves. In the new research cooperation “KoKo Zollverein” (short for “Copter flights on the Zollverein coking plant”), the FZN is developing and testing this new methodology. To this end, the experts are working closely with the Zollverein Foundation and the Materials Science Research Department of the German Mining Museum Bochum (DBM) in Bochum. Satellite images and non-destructive lasers will also be used in the troubleshooting process. Ultimately, the aim is to carry out a detailed examination of the building fabric and damage assessment for the first time.

For more than 30 years, coke, gas and other by-products were produced at the Zollverein coking plant in Essen. During peak operation, it was considered one of the most modern coking plants in Europe. Today, the plant is an architectural monument that, together with the neighboring Zollverein coal mine, has been declared a UNESCO World Heritage Site. “In addition to the cultural play and development of Zollverein, the preservation, safeguarding and protection of the UNESCO World Heritage Site is our top priority,” says Prof. Hans-Peter Noll, Chairman of the Board of the Zollverein Foundation. “Zollverein is a place of change and the future, so it is a perfect fit that a research cooperation is now testing cutting-edge technology in this huge real laboratory, which will soon open up new possibilities for other industrial-cultural sites.”

“The Zollverein World Heritage Site is a breath-taking landmark and an important witness to industrial innovation in our region” says Prof. Tobias Rudolph, project manager at FZN. “Every time we are on site with our scientific team, we get completely new perspectives. We are now expanding that with a sensor view from above and inside.” Indeed, it’s not just the outdoor facilities that are coming under the microscope; the interiors will also be evaluated. To do this, the drones take optical, thermal and multispectral resolution images that allow conclusions to be drawn about the condition of the materials. Where can rust be found? Where is verdigris or spalling? What is the overall condition of the objects? “At best, we can visualize all of this and then make a recommendation as to where the need for renovation is most urgent,” Bernsdorf explains.

For a holistic picture, FZN experts fuse drone data with satellite images from the European Copernicus program, which provide important information about the daytime surface. In addition, they combine the information from the air with on-site measurements in which a laser scanner scans the individual objects centimeter by centimeter. “For the first time, we are thus bringing together expertise from the fields of geomonitoring and materials science at a cultural and historical site. The idea of detecting material damage by interpreting and correlating various drone-mounted sensors together in a network is thereby a completely new approach in the field of historic preservation,” explains Prof. Rudolph enthusiastically. If successfully applied, the method will be transferred to other industrial heritage sites. (THGA/Si.)

Resources are becoming scarcer, energy prices are rising. In addition, dependence on third countries has led to a global rethink when it comes to extracting raw materials. New ways must be found to extract valuable materials ecologically and economically. That these ways also follow unusual ideas is shown by a new project that has now started at the Research Center of Post-Mining (FZN) at the TH Georg Agricola University (THGA), Bochum/Germany: Over the next two years, the scientists in the “IAW3³” project will investigate whether strategic raw materials can still be extracted from mine water and which methods are best suited for this. With the help of new processing technologies, critical metals in particular are to be extracted. The experts not only look at the mine water itself, but also examine its precipitation products and treatment residues. They conduct their investigations at various mines in the Ruhr, Saar and Ibbenbüren regions.

The research project is initially funded by the RAG-Stiftung, Essen/Germany, until 2024. The full project title is: Innovative processing technologies and their potential for recovering valuable materials from mine water, precipitation products and processing residues at Ruhr, Saar and Ibbenbüren with special consideration of critical metal resources, in short: IAW3³.

“For us, post-mining does not only mean dealing with the challenges that the coal industry has left us. In the field of post-mining, it is also a matter of developing new possibilities and opportunities in the former coalfields,” says Bärbel Bergerhoff-Wodopia, Member of the Board of Executives of the RAG-Stiftung. “The new research project around the extraction of strategic raw materials from mine water is a highly exciting field of the future that is geared towards sustainability. It can contribute to reducing dependencies in raw material extraction. Just how important independence can be in this field is particularly evident to us these days. That is why we as the RAG-Stiftung are very happy to support this special project.”

“We see mine water as a potential stream of valuable materials,” says Prof. Christian Melchers, who heads the project at FZN. “The innovative thing about our idea is that we not only look at the mine water itself, but also examine the residues from treatment and its precipitation products. Precipitation refers to the separation of a dissolved substance from a solution.” What is sludge and silt for the layman is a real treasure trove for the experts at the FZN: “Recent investigations have shown that it contains, e. g., magnesium, which is used in engine construction. In the past, there have already been supply bottlenecks with the Chinese market leader. At best, we want to counteract these dependencies,” explains project member Bastian Reker (Figure 1). Rare earths, which can drive the expansion of renewable energies, or lithium, which is crucial for e-mobility, are also found.

The scientists are also examining the quantities of the critical element germanium in the mine water. “This is a by-product that is otherwise only produced during zinc extraction and is essential for the coating of fibre optic cables and thus for the expansion of the network,” says Reker. “Currently, all of these raw materials are being extracted worldwide under sometimes dubious environmental standards that affect people and the environment equally,” adds Prof. Melchers. “This simply no longer fits in with the spirit of the times and the growing ecological awareness in our society. We therefore want to initiate a rethink, accompany the processes scientifically and thus look for new possibilities on our own doorstep.”

The mine waters that are lifted from great depths with pumps in the former coalfields of the Ruhr, Saar and Ibbenbüren show a wide range of different mineralisations and enrichments – depending on the regional geology, hydrogeology and other influencing factors left behind by mining, explains expert Prof. Melchers: “We are now examining the extent to which it is also economically worthwhile to collect and process these valuable substances.”

To this end, the scientists will be setting up their own precipitation reactors at suitable locations in the coming months. In them, iron and other metals will be separated in a targeted manner by adding oxygen. They want to transfer the knowledge they gain from designing the plants on a laboratory scale to experimental plants on a large scale. In the IAW3³ project, the scientific team is also testing completely new processing technologies. Hyperspectral sensors, e. g., could help to directly detect the critical metals in mine water and co. and assess their mineralogical composition in a matter of seconds. The most promising methods are to be further developed at the FZN. (THGA/Si.)

Coldewey, W. G. (2022): Handbuch Hydrogeologie. Das Standardwerk für Lehre und Praxis. First edition. 713 pages, 104 tables, 178 figures and 42 appendices. Vulkan Verlag GmbH Essen (Figure 1).

The importance of water as a geo-resource for the people and the environment has been emphatically brought to the attention of the public in recent years. The orderly handling of water must be the focus of all professionals who are responsible for processes that influence the natural water cycle. This involves the extraction, use, purification and discharge of water, but also the protection of the public from the power of water, its retention and availability. Hydrogeology provides the basis for an understanding of the processes surrounding the geo-resource water.

The Handbook of Hydrogeology lives up to this requirement and undoubtedly offers benefit for all hydro geologically interested professionals in the sense of a standard work for teaching and practice. Thus, already when opening the book, which is widely illustrated with figures, tables and appendices, the competence of the author, who has been known for decades in wide circles as a proven expert in hydrogeology, becomes clear. Indeed, one very quickly feels literally “at home” in the topic and hardly wants to put it down.

The book is divided into the major chapters “General Hydrogeology”, “Applied Hydrogeology” and “Groundwater Characteristics”. From a scientific-technical point of view, the physical-chemical basics covered in this work are very welcome. This includes the numerous definitions of terms used throughout from standards, guidelines and guidance documents. Formula symbols are abbreviated with the letters that are also used internationally, equations are documented by figures that explain the corresponding formula designations and substantiate them with example calculations.

The present work is characterized by an extensive bibliography and a comprehensive compilation of relevant DIN standards. Literature has been compiled according to the usual citation specifications in geology, allows a good overview of the scope and facilitates the finding, even of unusual titles. The appendix contains various thematic maps from the fields of geology, hydrogeology and water management, which are very clearly illustrated in color in the form of a model landscape.

The book facilitates the user’s entry into and in-depth study of all aspects of hydrogeology through its very thoughtful and descriptive layout in terms of graphics and topics. The quality standard of the author, who has a profound experience in the field of hydrogeology, both in practice and in teaching, is evident. Both experienced professionals and young people will certainly be attracted to the work in their interest in hydrogeology. From the point of view of the depth of content, the scope and the elaborate design of the book, the price of 149 € is reasonable.

In the sense of creating transparency and understanding for the manifold questions that arise in view of the complexity of the georesource water, this standard work can be recommended for reading and use by all experts and students dealing with the subject, but also by all other interested parties.

Prof. Dr.-Ing. Peter Goerke-Mallet, Research Center of Post-Mining (FZN), TH Georg Agricola University (THGA), Bochum/Germany

Mining leaves its mark – water in particular as a resource in the former mining regions is affected by the consequences of intensive raw material extraction, some of which has been ongoing for centuries. The key issues in this year’s “NACHBergbauzeit in NRW” conference (Figure 1) looked at the challenges involving the long-term management of water and the resulting effects from the planned increase in pit water levels. The District Government of Arnsberg as the mining authority for North Rhine-Westphalia and the TH Georg Agricola University (THGA), Bochum/Germany, held the joint specialist conference for the sixth time on 10th March 2022. The 250 or so participants exchanged their professional views online on the subject of “Pit water – planned on paper, discussed online”.

In his welcoming address, Hans-Josef Vogel, District President of the District Government of Arnsberg, emphasised the vital cooperation of universities and public administration: “This innovation partnership guarantees the scientific basis for problem solving in the economy, in communities and in civil society. The research into post-mining is a very tangible example of how we can open up new vistas together, with a view to climate protection.”

Bärbel Bergerhoff-Wodopia, Member of the Board of Executives of the RAG-Stiftung, Essen/Germany, added: “In times of a recycling economy, but also with the increased use of georesources, among other things, for electric mobility, it is important to think about post-mining. For only with our post-mining experience can we succeed in using georesources sustainably today and in the future – this will only be the case if post-mining is considered right from the start in every mining process.” New ideas and innovations are needed to resolve the challenges of the future together and to unlock brand new potential.

The presentations of the conference primarily addressed the effects of the planned increase in pit water on the mining districts in North Rhine-Westphalia and in the Saarland. The speaker, Thomas Im-grund from DMT GmbH & Co. KG, explained the possible effects of rising water levels on pit gas extraction. He also estimated the overall possible impacts of the process on the emission of methane on the ground surface. He concluded with a positive outcome. With targeted extraction and utilisation of the pit gas, uncontrolled emissions would decrease considerably. The rising pit water would also cause flooding of flow paths and a lower gas output overall in the long term.

Manuela Nie and Mario Sommerhäuser from the Emschergenossenschaft/Lippeverband (EGLV), Essen/Germany, offered a very different view on the pit water. In their pre-sentation, they addressed the significance it currently has and will have on the flora, fauna and water quality in the Emscher-Lippe region. Overall, they acknowledged that the region demonstrated good ecological development. The impacts of pit water discharge are currently very low due to fast and heavy dilution in the river waters, which is perhaps why the salt concentration is well below the limit – and they continue to decrease. According to the EGLV’s plans, the whole Emscher will be completely free of pit water from September 2022.

The presentations in the second part of the event covered the challenges faced regarding the responsible handling of PCBs. This abbreviation stands for polychlorinated biphenyls; chemical chlorine compounds which were used in the coal mining industry, e. g., in hydraulic systems, transformers and gearboxes. The fact that PCBs are potentially harmful to human health and the environment was not known for some time. The use of this substance was not forbidden until the mid 1980s – traces can still be detected in pit water today, albeit in very low levels.

In his speech, Michael Denneborg presented a report commissioned by the North Rhine-Westphalian regional government to assess possible risks for ground waters and surface waters. In it, the qualified geologist from ahu GmbH, Aachen/Germany, looked at the possible effects of rising pit water on the discharge of PCB and other residual materials. His conclusion: Overall, higher pit water levels reduced the flow of PCB and the pit water volume in bodies of water over the long term.

Following this, Joachim Löchte from RAG Aktiengesellschaft, Essen/Germany, presented the intensive monitoring programmes developed by the company in order to constantly check and systematically record the flow of PCB into pit water. He covered the technical challenges faced during monitoring in particular. He also presented current projects the RAG is working on, with scientific support from the Research Center for Post-Mining (FZN) at the THGA, with the aim of further minimising contaminants, e. g., using special filters and treatment plants.
(Carmen Tomlik (THGA)/Si.)

At the Research Center of Post-Mining (FZN) at TH Georg Agricola University (THGA), Bochum/Germany, Julia Tiganj (Figure 1) is studying the socio-economic aspects of post-mining. In times of raw material scarcity and the energy transition, the economics researcher’s attention is especially drawn to China. Will the world’s second-largest economy manage the transition to renewable energy? What are the greatest challenges they face and what will the rest of the world gain? There’s not much research yet but the topic is super hot right now, says Julia Tiganj being interviewed by Carmen Tomlik from the FZN.

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Carmen Tomlik: In your expert opinion, where does China stand on the energy transition and on post-mining?

Julia Tiganj: That depends on where you look. There are many provinces in China which vary greatly, e. g. in their reliance on coal. There are regions which are already working sustainably. On the other hand, there are provinces whose economies rely heavily on mining. Here, coal secures a lot of jobs, taxes, pensions and, of course, supports national economic growth – which is one of China’s primary goals. As you can see, the gulf between them is massive. For this reason, it will be difficult in future to meet the many different economic requirements and the needs of the people in the different regions. There are interesting pilot projects, e. g., some people are thinking of using old, disused mines to create “underground cities” to compensate for the demand for space in the cities. Of course, the idea is controversial – but it is quite an innovative one and begins to face the issues of post-mining. China is also a global leader in satellite technology. Here the question is how far this expertise is being used to monitor the legacy left by mining.

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Tomlik: China without CO₂? What are the greatest challenges on the way to carbon neutrality?

Tiganj: Coal is still the easiest and safest way to secure a stable energy supply. China intends to become carbon neutral by 2060. However, this also means that the highest CO₂ emissions peak needs to be behind them by 2030. At the moment, they are therefore still building new coal power plants which are designed to run for 40 years. These power stations, however, meet the latest environmental standards and are intended to replace out-dated, inefficient plants. At the same time, China is already a market leader in renewable energy. Around 90 % of the energy concentrates used in solar panels, silicon batteries or wind power are made here. Until now, preventing climate change had no priority within China itself. The latest five-year-plan, however, demonstrates that China wants to become “greener” and has recognised the urgency of this.

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Tomlik: What does “greener” mean in this case?

Tiganj: That’s the next big challenge. After all, renewable alternatives also produce CO₂ and are not yet 100 % recyclable. The rotary blades of wind turbines, e. g., are disposed of as hazardous waste after being in use for only 20 years. Air pollution or poisonous wastewater threatens certain areas of land and the people who live there so that clean energy can be produced in a different part of the world. This is not sustainability, this is a displacement of climate problems from A to B under the smokescreen of a green future. As you can see, the whole setting is far from ideal – and now we haven’t even talked about the labour market and the long-term challenges that structural change would bring to Chinese coal-mining areas. Nevertheless, it is an important step to say: We are reorienting ourselves, we are doing research and we want this transformation.

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Tomlik: What would the rest of the world gain if China becomes carbon neutral?

Tiganj: When large, influential players like China pay more attention to sustainability and protecting the climate, this has a positive impact on everyone else. Direct neighbour states often orient themselves in accordance with dominant China and its approach. Depending on import and export dependencies, other countries may also find it necessary to reorient themselves in order to keep up. Also, China is an important trade partner in rare earths and is highly influential on the advances of e-mobility in Europe or the USA. This and many other aspects are factors which are helping processes to become more sustainable globally. Generally, a lot of research and development is still needed in order for the energy transition to be successful. Here too, a “green” China could become an international driver of innovation. (THGA/Si.)

The ground below Gronau and the surrounding area is a challenge, even for geologists: Salt has been mined here intensively for almost 50 years. This has created large cavities, known as caverns, at depths of between 1,000 and 1,500 m. Most of them are now used to store natural gas, crude oil or helium, and are important to the economy of the entire region. Right next to this cavern field is Amtsvenn nature reserve, spanning 9 km² of moorlands.

This special place has been the frequent source of tension over the years – not only in the geological structures themselves, but also between residents, the city and the various operating companies. The main cause of this tension is the ground motion, which in the long term could lead to subsidence in the area and consequently cause damage to buildings and alter the water balance. But what is actually caused by mining? And what is caused by nature? This is where a new, unique research cooperation, formed to investigate Epe cavern field, comes in. The new cooperation includes the City of Gronau, the citizens’ group Bürgerinitiative Kavernenfeld Epe e.V. (BIK), EFTAS Fernerkundung Technologietransfer GmbH and the Research Center of Post-Mining (FZN) at TH Georg Agricola University (THGA) in Bochum (Figure 1). Together, they want to find a solution to determine where the ground motion in the cavern field is coming from. “In order to understand the processes in detail, it is crucial to carry out tailored, extensive monitoring of all factors that are having an impact on ground motion in the region,” explains Prof. Peter Goerke-Mallet from the FZN. This includes satellite data from Copernicus, the EU’s space programme, as well as the use of local infor-mation and the knowledge of residents.

“Above all, we want to use this new research cooperation to establish a foundation of trust,” says Prof. Goerke-Mallet. “Today, all mining projects require transparency and the extensive sharing of expertise with society and vice versa. In this project, we can benefit from the knowledge of local people in a really special way,” says the experienced mine surveyor and mining expert. “After all, the residents know best where the challenges lie in their local area and can observe and document the changes in the landscape and buildings, sometimes even over years and decades. The research cooperation for Epe cavern field therefore offers a highly innovative approach to conflict resolution through active participation.”

Holger Perrevort, chair of the citizens’ group, also hopes that the cooperation will improve the flow of information and create more opportunities for involvement. “Above all, we want more accurate information about what is happening right below our very feet.” A lot has gone wrong here in the past, according to the resident. Not enough attention was paid to the potential risks and impact of ground motion, Perrevort says. “As a citizens’ group, we have been fighting for our concerns to be taken seriously for years already. Politicians must also fulfil their duty of care towards residents, e. g., if cellars get wet or cracks appear in walls.”

The experts at the FZN in Bochum also want to get to the bottom of this damage. Over the next twelve months, they will perform specific measurements to investigate the issue – using drones, which can detect changes in vegetation, e. g., and satellite data, which the specialists from EFTAS in Münster will analyse. “But we will also make a deliberate effort to visit the locals, to conduct building inspections and measure buildings and properties that may have been affected by ground motion,” explains Prof. Tobias Rudolph, a geomonitoring expert at the FZN. “Close cooperation with local residents is vital for us to be able to complete this work, so we are extremely grateful that new doors have been opened to us in this respect – in the truest sense of the word.”

The scientists are likely to spend most of their time analysing the large volume of data: “We will examine information on the groundwater and the surrounding bodies of water, on the ground, the subsurface and the caverns, among other things.” Their contact with members of the citizens’ group and the city also gives them access to many other important sources of information, such as private measuring points, springs and municipal geodata, which they plan to link together and analyse. Naturally, this will not all be done behind closed doors, but rather – in keeping with the pursued aim of transparency – alongside regular information events, where the results will be freely disclosed and discussed.

This planned approach also convinced Rainer Doetkotte, the Mayor of Gronau, to add his signature. Most importantly, he can envisage the positive effects this cooperation will have on the region in the long term: “This research cooperation marks the start of an important project, and I am delighted that we have the FZN, EFTAS and BIK on board for it. Ultimately, we want to provide the interested public with detailed information using the results obtained, in order to resolve any concerns, dispel any prejudices and increase acceptance within society. The results can also be used to create other concepts in the future, bringing further scientific progress to Gronau.” (THGA/Si.)

Intensive mining has caused the terrain and surface to sink so substantially in some areas in the Ruhr area that large depressions have formed – referred to as polder areas. In these areas, waterways cannot always flow freely anymore. The “lower” areas therefore need to be continuously artificially drained to prevent the accumulation of water from rivers and lakes. These processes have a big impact on the overall water balance in the region. In a new project, the Research Center of Post-Mining (FZN) at TH Georg Agricola University (THGA), Bochum/Germany, is therefore investigating how water management in the Ruhr area can be made more sustainable. Any resulting measures could particularly benefit the farmers and the forests in the region. The planned environmental monitoring should also improve the management of extreme events, such as heavy rainfall or long periods of drought. This is where the “MuSE” project (Multi-sensor geomonitoring for sustainable polder management) comes in.

MuSE is being funded by RAG-Stiftung until 2024. Bärbel Bergerhoff-Wodopia, Member of the Board of Management at RAG-Stiftung, stresses: “At RAG-Stiftung, we believe we have a responsibility to find solutions to the challenges that mining has left behind. With this in mind, we are working closely with THGA and the Research Center of Post-Mining and are supporting the “MuSE” project with firm conviction.”

“In areas where the land has sunk as a result of coal mining, that is where large depressions have formed in the ground, the soil moisture has also changed,” explains Prof. Tobias Rudolph from the FZN. In some cases, entirely new bodies of water have been created, like Weihnachtssee lake or Ewaldsee lake in Herten (Figure 1). “This naturally has an impact on the use of land and resources for agriculture, forestry and water management. This has far-reaching consequences – particularly because of climate change,” says the geomonitoring expert. The lower levels of precipitation and increased periods of drought over recent years have made this clear: “The Ruhr area needs more water in order to cope with the effects of climate change in the long term – even if the events of the last few weeks may cause you to think otherwise.”

Prof. Rudolph and his team are therefore investigating alternative solutions for the management of polder water drainage, namely: “What can we do to make better use of this water? And how can we optimise irrigation planning in general?” In the new MuSE research project, the experts at the FZN are investigating how to redesign polder management so that it is efficient and sustainable. Higher groundwater levels and the economic and technical use of elevated groundwater and surface water, e. g.,  could help to minimise drought damage in agriculture and forestry. Targeted monitoring can also help ensure that polder areas are better set up to cope with heavy rainfall and flooding.

To this end, not only are the experts at the FZN analysing the historic data available, they are also using modern satellite data and performing their own measurements in selected test areas: “We use various sensors to measure the soil moisture. We also analyse water level data and survey the vegetation using our drones, examining the health of the plants at the same time. We combine this information that we have gathered locally with remote sensing data supplied by the European satellite programme Copernicus and evaluated for the first time with regard to this issue,” explains Xiaoxuan Yin, a specialist in radar interferometry and remote sensing who joined the FZN in order to work on the project.

Then it gets a bit trickier: “We combine all the different pieces of information in a 4D model using time as the fourth dimension,” explains Yin. This enables the scientists to track the changes in the water balance over the decades and model these changes digitally. “Ideally, this will enable us to make recommendations on long-term land and resource usage and help to improve the environmental conditions in agriculture, forestry and water management.” (THGA/Si.)

The history of mining is long – but the history of post-mining will be much longer. For five years now the Research Center of Post-Mining (FZN) at the TH Georg Agricola University (THGA) in Bochum/Germany has been attending to the issues that emerge as mining activity ceases. As the world’s first institution, it takes a comprehensive look at the post-mining era. The scientists are examining not only the tasks that mine water or former mining areas leave behind. They are also developing modern monitoring methods, advising affected regions on the structural transformation and trying to preserve the industry culture.

“The challenges of post-mining are complex, that’s why we are also becoming increasingly complex”, says Prof. Ulrich Paschedag, Head of FZN (Figure 1). “Since October 2015 we have been pooling the necessary know-how to shape the consequences of mining in a technically, economically and environmentally friendly manner.” In the interdisciplinary team around 40 independent experts in mining, geology and geo-technology, hydrogeology, chemistry, electrical engineering, materials science, land development, mine surveying and economics, all work closely together. This is the core around which a broad network has been established, nationally and internationally.

In the beginning the focus was still on researching the so-called perpetual tasks of the coal mining industry, but the FZN has been expanding its focus to this day. From the integrative approach come the four research areas: perpetual tasks and mine water management, geomonitoring in post-mining, materials science for the preservation of the industrial heritage, as well as reactivation and transition.

The experts are currently developing the scientific bases for an ecologically and economically compatible mine water ascent. The experiences from other European territories, in which such processes have already taken place wholly or partly also help. “The mine water rise is technically controllable”, says Prof. Christian Melchers. “Now it is about designing sustainable water management systems within the closed mines. Only then can the water resources in the former mining landscapes be reshaped in a near-natural way”, states the expert. The findings can also be transferred to other mining activities such as lignite or the gas and oil industry.

In the future geomonitoring will be about monitoring the impacts of mining over the long term using modern technology. “For this we must skilfully connect lots of information – like with a puzzle”, states Prof. Tobias Rudolph describing his area of research. Satellite data, historical maps, soil samples or multispectral aerial views with the drone are used here. “From these we can draw conclusions, e. g., about soil changes and detect changes in the vegetation.” In close cooperation with materiaIs scientists at the German Mining Museum (DBM) in Bochum, new methods are also being developed at the THGA to slow down or ideally stop ageing processes. The post-mining experts are helping to preserve the industry culture such as old winding towers or blast furnaces.

The cutting-edge research in the area of post-mining is in demand worldwide. More and more countries are interested in a far-sighted approach for handling active and former mining sites. The knowledge from Bochum also helps to make future mining processes more environmentally friendly. The FZN is in constant dialogue with its many international partners. It will also remain challenging in the future. “We are concerned with highly complex questions and interrelationships that take place in locations that are frequently still difficult to access. Underground, e. g., in places most people have never been to, and which will soon become inaccessible to all of us”, says Prof. Paschedag. “This is the reason why we, as scientists, have to make a special effort to formulate our post-mining findings in a way that can be generally understood by everyone.”
(THGA/Si.)