Classen and Schüttrumpf Environ Sci Eur (2018) 30:18 https://doi.org/10.1186/s12302-018-0146-0

COMMENTARY Open Access Institute of hydraulic engineering and water resources management (RWTH Aachen University): an overview of research focus and training Elisa Classen and Holger Schüttrumpf*

Abstract Water is an essential element and highly valuable resource in life. Between the priorities of environment, people and economy, it is of increasing importance to fully understand the fundamental force of water to be capable of han‑ dling waterborne events—such as fooding—manage and ensure water quality and availability, and utilize hydraulic energy. The Institute of Hydraulic Engineering and Water Resources Management (IWW) at RWTH Aachen University has a long research tradition in this feld. Going back to the founding year of the university in 1870, the chair is based on the work of civil engineer Otto Intze, who is best known for his pioneering contributions in construction of dams and elevated water tanks. Ever since then, the institute has broadened its research spectrum and is today focusing on food protection structures, hydraulic engineering design, integrated coastal zone management, morphodynamics and ethohydraulics. In a comprehensive approach, physical model experiments are combined with feld measure‑ ments and numerical simulations to investigate a wide range of projects. With its annually organized International Symposium on Hydraulic Engineering (IWASA), the institute also ofers information to a wide audience on highly topi‑ cal aspects in the feld of water engineering works and water management, while at the same time bridging the gap between science and industry. The institute is part of the “Project House Water”, a research network at RWTH Aachen University that was established within the framework of the German excellence initiative. Here, scientifc competen‑ cies from the felds of ecotoxicology, process engineering, geography, sociology, economy and hydraulic engineering are focussed to allow for an interdisciplinary, holistic assessment of fooding events and their impacts. Keywords: Engineering, Flooding, Coasts, Sediments, Hydraulic energy, Hydrodynamics, Ethohydraulics, Morphodynamics

Background fundamental and applied research in the feld of water About 150 years of hydraulic engineering in Aachen— engineering, food control and dam construction in beginning and development of the IWW Aachen. Te name of the Institute of Hydraulic Engineer- In the late nineteenth century, civil engineer Otto Intze ing and Water Resources Management (IWW) and its started the long tradition of engineering at RWTH professoriate changed in the following decades, but the Aachen University—at that time still called the First research focus was always kept. In 2013, the chair was Prussian Institute of Technology: With his frst lectures provided with a new ofce building and experimental in hydraulic engineering, Intze prepared the ground for laboratory hall: a foor area of 2250 m2 housing perma- nently installed tilting, stepped and annular fumes and a water circulation system with fow rates of up to 1500 l/ *Correspondence: [email protected]‑aachen.de min and a volume of 400 m3 provide excellent opportuni- Institute of Hydraulic Engineering and Water Resources Management, RWTH Aachen University, Mies‑van‑der‑Rohe‑Strasse 17, 52074 Aachen, ties for large-scale model experiments. Apart from that, Germany the hall is equipped with a modular 30 m fow channel,

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used for ethohydraulic studies, overfow and dike experi- the Exploratory Research Space (ERS) at RWTH Aachen ments. Te open space can be used for temporary instal- University and aims to promote interdisciplinary projects lations and smaller physical model experiments (Fig. 1). under one roof by combining expertise from diferent Te Institute operates an own model building depart- faculties. Including, but not limited to the project house, ment and is assisted by metrologists to support the indi- the following research felds are currently in focus of the vidual research projects in-house and during feldwork; institute IWW. as of beginning 2017, 43 scientifc and non-scientifc staf members are employed. Flood risk management Te institute is associated with a non-proft friends High water events recurrently pose an existential threat association to support teaching and research activities. to life and property of individuals, infrastructure, agri- Te association also provides assistance in funding con- culture and industry in food-prone regions. Within ference attendances, lectures and feld trips and fnan- minimal time, personal and cultural assets can be dam- cially contributes to the publication of scientifc work. aged or irretrievably destroyed during a food disaster. To promote the contact between academia and industry, Tese events have lasting efects for human and nature the International Symposium on Hydraulic Engineer- and echo for a long time, such as the disastrous fooding ing, Aachen (IWASA) is held every January, for almost alongside Elbe and Danube in 2013 or the fooding of the 50 years. It is renowned among experts and gives the Oder river in 2010. opportunity to discuss highly topical water themes as Yet, fooding risks are not limited to inland waters but well as to establish contacts for future ventures. also occur at open waters as a result of weather phenom- ena such as Hurricane Matthew in the Western Atlantic Main text (2016) or the tsunami in Japan in 2011, which also led to Research in the feld of hydraulic engineering at IWW a nuclear disaster at the Fukushima plant. While the pri- Te research area of the IWW is broadly based and vate, non-material loss can hardly be quantifed, fooding includes key topics from the felds of high water risk events cause substantial costs amounting to billions, such management, hydraulic engineering structures, navi- as hurricane Katrina in the US (2005) which killed more gable waterway constructions, hydroelectric power, than 1800 people and caused damage of over 80 billion pumped-storage plants, fsh protection elements, sedi- US$. Tese numbers clearly emphasize the importance ment transport and morphodynamics, coastal engineer- for the development of food protection and food man- ing and water quality improvement. Projects are typically agement tools. Due to human intervention, like river reg- assessed both in fundamental and applied research, ulations and land sealing, as well as an increasing dense to not just give an understanding of the involved pro- settlement in food-prone regions, the need for research cesses but recommend options for tailor-made solutions. in this feld is also underlined. Within its projects, the institute is working in close coop- For about 20 years, high water risk management is a eration with research facilities and administrative boards core topic at IWW: as an important element in food con- in Germany and worldwide, such as the Federal Water- trol is the technical protection by construction measures, ways Engineering and Research Institute (BAW), the IWW is evaluating the physical processes of fooding German Federal Institute of Hydrology (BfG), the Min- to identify weak points, which lead to structural break- istry for Climate Protection, Environment, Agriculture, downs upon food events. Trough this, suggestions for Conservation and Consumer Protection of the State of improvement of existing and new food defence systems NRW (MKULNV) or the Israel Institute of Technology. are defned [2]. For instance, food polders are used to Te IWW is further integrated into the Project House improve water retention and thus attenuate food peaks Water [1], a joint venture of six RWTH institutes with a in the course of small-scale and average food events. research focus on water. Te project house is funded by Breach formation processes and their infuencing factors

Fig. 1 Experimental hall at IWW Classen and Schüttrumpf Environ Sci Eur (2018) 30:18 Page 3 of 9

are still subject to a number of uncertainties. Within the towards food risk management have to be critically BfG commissioned project “Physical Model Tests of Dike reviewed [6]. Breaches” within the framework of the “National Flood Protection Program for Optimization of Havel Polder”, Hydraulic engineering design the targeted flling of food polders through dike breaches Hydraulic structures cover a variety of waterside build- is assessed and technically optimized. In that context, ings that can basically be categorized into two groups: physical model tests of dike breaches will be performed the frst set comprises constructions with a protective in the hydraulic laboratory at IWW to quantify the infu- function, like retention reservoirs, dikes, bank reinforce- ence of geometric, hydraulic and geotechnical boundary ment structures or food barriers. Te second group conditions on dike breach formation (Fig. 2). includes constructions that enable the personal and Further current projects at IWW address issues industrial use of water, such as drinking water networks, related to revetment stability during swell load (project irrigation facilities, waterways, wastewater treatment sys- HYGEDE, supported by BMBF). In addition, coupling tems or hydropower stations. Against the background mechanisms of high and ground water are analysed [3] to of the European Water Framework Directive of 2000, minimize food damage in underground buildings such as which aims to ensure a good chemical and ecological tunnels and car parks. quality of water bodies, hydraulic engineering is set in a While the aforementioned topics relate to the immedi- sense between conficting priorities, namely the require- ate efects of fooding, a consequential problem originates ments of engineering itself and those of sustainability and from pollutants (soluble as well as sediment associated) environmental protection. In accordance with the direc- that are spread during high waters and which can impair tive, alternative fsh protection structures up- and down- entire ecosystems. Whereas the hazardous potential of stream of water facilities are developed and optimized to chemicals is mostly known, the long-term efects of so- allow for a safe fsh passage. In this context, studies are called emerging pollutants (e.g., pharmaceuticals, per- performed at IWW, to analyse the orientation and search sonal care products, biocides) is not fully understood yet behaviour of fsh in front of bar racks that are typically and, for this reason, is investigated at IWW in interdisci- used to prevent fotsam and animals from entering pipes plinary projects [4, 5] (Fig. 3). and turbines (Fig. 4). In general, it is observed that high water models and By understanding the movement habits of fsh at such surveys from past decades have to be adapted to take barriers, alternative solutions can be engineered to into account the ongoing infuence of the global cli- improve animal welfare without signifcant loss in value mate change. In consequence, related recommendations for the afected companies.

Fig. 2 Construction work on a physical model of Havel polder. A base frame with a length of 34 m and width of 11 m is set up with concrete build‑ ing blocks to form a basin; afterwards, a model dike with a breach will be constructed inside. Flooding this structure will give insight into the flling characteristics, so that constructional measures for an intended flling of the polder can be concluded Classen and Schüttrumpf Environ Sci Eur (2018) 30:18 Page 4 of 9

Fig. 3 Hydro-toxic studies on sediment-bound pollutants in the circular fume at IWW. Rainbow trouts (Oncorhynchus mykiss) were exposed to clear water (negative control, left) and water–sediment-mixtures (right) that were artifcially spiked with environmental pollutants, e.g., polycyclic aromatic hydrocarbons

Fig. 4 Behavioural studies on fsh within the fow channel. Diferent types of bar racks are tested on common roaches (Rutilus rutilus, left) and com‑ mon breams (Abramis brama, right)

Te combination of hydraulic engineering and environ- to a higher elevated reservoir. Once, energy is needed, mental sustainability is approached in further projects at the water is released to a lower basin using the difer- IWW: with phasing out nuclear energy in Germany until ence in altitude to drive generators. As this operating 2022, alternative energy sources have to be exploited. mode requires special topological conditions (large-scale An overall challenge with renewable energies is their basins at diferent heights), the construction of such volatility: for instance, solar power is limited by day/ plants has not only a high environmental impact but is night cycles and wind farms are dependent on weather limited to mountainous landscapes. To overcome these conditions. Terefore, an important aspect in promot- restrictions, pumped-storage plants should be developed ing alternative energy concepts is the development of to work underground using for example existing caverns reliable energy storage systems. Overground pumped- from former ore or coal mining. Tus, the main disad- storage plants have been used for this purpose for over vantages of overground pump storage reservoirs (topog- 100 years: in a frst step, electricity is used to pump water raphy, nature conservation and often large distances Classen and Schüttrumpf Environ Sci Eur (2018) 30:18 Page 5 of 9

between place of energy production and place over are endangered; about 20% of the European coastline energy consumption) can be bridged. A major challenge is seriously afected by erosion. In addition, frequency of this new type of pump storage plant is the flling and and intensity of storm surges have increased in the past emptying process of the underground caverns to ensure while at the same time a rise of sea-level by up to 80 cm energy storage and energy production in a given time is predicted for this century due to global warming [8]. interval. Terefore, researchers from IWW numerically Protection of coastal habitats has, therefore, become a and experimentally analyse hydrodynamic processes dur- fundamental future challenge: in terms of engineering, ing flling and draining of cavities, to defne requirements it is important to understand static loads and mechani- for the underground reservoirs (Fig. 5). Tese specifca- cal stresses on hydraulic structures upon extreme water- tions can be used either to characterize existing caverns related events. At IWW, this topic is addressed, for according to their usability or to create completely new example, in the BMBF-funded project EarlyDike, which underground storage plants. Nowadays, the develop- focuses on the development of early warning systems to ment of underground pumped-storage plants is in a very detect sea dike failures at a very early stage: at present, early stage. Several ideas were developed but no under- dike monitoring typically includes annual inspection of ground pump storage reservoir was realized so far. Tis viewable dike areas, such as controlling height and cover is due to the uncertainty of the geological conditions, the condition to detect any weak points (e.g., signs of ero- unknown processes during flling and emptying including sion, changes in vegetation, burrowing animals). Exist- interaction with the geological properties, operation and ing warning systems, however, only take into account placement of turbines and pumps in several hundreds of observed and forecasted changes in water level; there meter depth below the surface and other reasons. Any- is no system yet to monitor structural properties inside way, the idea of placing a pump storage reservoir in the sea dikes. Tis is the starting point for project EarlyDike, underground is promising and implementation might be which uses sensors-equipped geotextiles to detect water possible after more research is carried out and open gaps intrusion inside dikes (Fig. 6). are solved. Yarn-like carbon sensor fbres are attached to a geo- textile in parallel strands and the fabric is then placed Coastal engineering between the sand core and the clay layer of a dike, fac- Coastal regions have always had an attraction to people ing landwards. With two types of sensor fbres, this setup and business: some of the most infuential cities reside at allows for monitoring humidity and structural stability waterside, where they represent gateways to the world; of the dike: if water is intruding the structure, it will be enormous values have accumulated there in the past cen- signalled by a change in conductivity between two par- turies. Moreover, coastal habitats also pose a high ecolog- allel sensor strands. A strain of the fabric, as caused by ical value as they substantially contribute to the overall deformation of the dike, can also be detected through ecosystem services (up to 40%) [7]. Yet, these landscapes the specifc sensor fbres. Both parameters are captured

Fig. 5 Model of underground pumped-storage plant. With a length of about 36 m, the model is used to assess fow conditions in cavities Classen and Schüttrumpf Environ Sci Eur (2018) 30:18 Page 6 of 9

Fig. 6 Dike models used in project EarlyDike. A Small-scale model, equipped with intelligent geotextile (B) for detection of water; C overfow of large-scale dike model

real-time and allow for quick protective and action meas- sediment fuxes on various timescales, ranging between ures in case of an impending dike failure [9]. Te studies minutes and centuries. Here, the morphology of riv- at IWW are supported by numerical analysis and aim to ers is afected not only by natural factors, such as a rise develop a fooding simulation software to predict food- in precipitation levels but also ecological processes and ing-afected areas, resulting consequences and mechani- anthropogenic interventions can have major infuences cal durability of protective structures. (e.g., glacial melting due to global warming). Te steady Another extreme water-related incident that afects growth of waterway transport increases the demand coastlines are tsunamis, which originate from storms or for improved inland waterways and ports, resulting in seaquakes. Due to their infrequent, but sudden occur- substantial changes of river morphology due to dredg- rence, the data situation is limited and it is rather difcult ing activities at riverbeds, straightening of watercourses to determine physical parameters from recent events. For and building of hydraulic structures. In a comprehen- this reason, researchers at IWW take a look back in his- sive approach, covering the complete river course from tory: large boulders have been found close and distant to spring to estuary, the sediment balance of the river Rhine coastal regions, covered by marine sediments, indicating was analysed over a period of 20 years as a collaborative that they originate from open waters. Tese rocks and work of IWW and BfG [10]. It showed that the Rhine their position in relation to the sea are used in a numeri- can be divided into four sections, namely the alpine, cal, inverse approach to calculate forces necessary to move impounded, free-fowing and delta section, each of which the boulders to the mainland (Fig. 7). Results are validated displays characteristic morphodynamics and sediment by model experiments and can be used afterwards as basis fuxes (Fig. 8). Sources and sinks of diferent sediment for designing protective structures at coastlines. types were identifed and balanced, taking into account data from previous studies using echo soundings and Morphodynamics sediment transport data. River systems are dynamic structures, shaped by move- Gathered information from the Federal Waterways and ment of water and sediments; the riverbed is thereby Shipping Administration as well as the federal provinces subject to a continuous accumulation and erosion of geo- has been merged with own data collected at IWW. Tis logical and biological materials. Te feld of morphody- includes, for example, measurements to assess the trans- namics focuses on these changes in river structure and port of fne and medium sand, as the bed-load collectors Classen and Schüttrumpf Environ Sci Eur (2018) 30:18 Page 7 of 9

Fig. 7 Analyses on boulders. a Perspective view and mesh model of a boulder deposited on the Island of Bonaire, Lesser Antilles, Caribbean Sea; b comparison between the original photograph and the numerical model

Fig. 8 Anterior Rhine in the Ruinaulta in canton Grisons, Switzerland

used in the included studies have a mesh size larger than Based on these results, a correction factor was deter- those particles. To estimate the amount of sand that was mined to allow for adjusting previously acquired data to not captured in the previous studies, bed-load collec- display the actual amount of transported sand. tors identical in construction were installed in the tilted As an overall result, the sediment balance study of the fume at IWW and fushed with water and a defned sedi- river Rhine ofers a baseline for future research on the ment mixture, representative of the Rhine bed. Compar- river Rhine as well as concepts for technical and con- ing the dry weights of the sediments accumulated in the structional measures, including sediment management. collector and those initially applied revealed average sand While the mere relocation of sand, gravel or clay is a losses between 10 and 50% depending on the type of col- visible sign of sediment fux, an associated issue is not lector used and the composition of the bed-load sample. noticeable at frst sight: as noted before, sediments are Classen and Schüttrumpf Environ Sci Eur (2018) 30:18 Page 8 of 9

often contaminated with harmful substances arising Deutsche Forschungsgemeinschaft (German Research Foundation); HYGEDE: Hydraulisch gebundene Deckwerke (hydraulically bound revetments); IWASA: from pharmaceuticals, chemically loaded wastewaters Internationales Wasserbausymposium Aachen (International Symposium on or fertilisers. By movement of these sediments, the con- Hydraulic Engineering, Aachen); IWW: Institut für Wasserbau und Wasser‑ taminants are further spread and constitute an ecologi- wirtschaft (Institute of Hydraulic Engineering and Water Resources Manage‑ ment); MKULNV: Ministerium für Klimaschutz, Umwelt, Landwirtschaft, Natur- cal hazard. Tis last aspect is leading back to the research und Verbraucherschutz des Landes Nordrhein-Westfalen (Ministry for Climate feld of food risk management presented at the very Protection, Environment, Agriculture, Conservation and Consumer Protection beginning of this article and nicely demonstrates the of the State of North Rhine-Westphalia). cross-linking of research projects at IWW. Authors’ contributions HS was responsible for the concept of the manuscript; EC drafted the manu‑ Teaching script. Both authors read and approved the fnal manuscript.

Te Institute of Hydraulic Engineering and Water Authors’ information Resources Management is a member of the faculty of HS studied civil engineering in Braunschweig/Germany and Grenoble/ civil engineering at RWTH Aachen University. It ofers France and obtained his doctorate in 2001 with a thesis on wave overtop‑ ping at dikes. Following his dissertation, he worked at the Federal Waterways lectures and seminars as part of the study programs civil Engineering and Research Institute in Hamburg. Since 2007, HS is director engineering, business administration and engineering, of the Institute of Hydraulic Engineering and Water Resources Management environmental engineering, and mobility and transport. at RWTH Aachen University. In 2015 HS was elected the new president of the BWK executive board. EC has a professional background in biology; she Te institute also provides interdisciplinary and cross- obtained her doctorate in 2011 with a thesis on structural and functional stud‑ faculty teaching in the felds of ecotoxicology, wastewater ies on plant receptors. Following additional training in project management, management and georesources management. Te range she worked for the biotechnology company QIAGEN before she joined IWW in 2016 as scientifc coordinator of the RWTH Aachen Universities’ research of courses includes not only basic subjects such as hydro- network “Project House Water”. mechanics, hydrology and hydropower, but also allows specialization in the disciplines of navigable waterway Acknowledgements construction, water management and surface mining, We thank Catrina Brüll, Christiane Eichmanns, Roy M. Frings, Elena-Maria and risk management. Te course portfolio is expanded Klopries, Verena Krebs, Jan Oetjen, Elena Pummer and Martha Wingen for by domestic and international feld trips, internships at providing photos of IWW research projects. engineering consultancies and in the construction indus- Competing interests try and gives the opportunity to work on topical research The authors declare that they have no competing interests. projects at the institute. With its experimental hall and Availability of data and materials its teaching equipment—e.g., a mobile, modular labora- Not applicable; presented information is based on previously published data tory system to demonstrate operating modes of hydrau- only. lic tubes and turbines—IWW allows students to study Consent for publication hydraulic engineering not only from a fundamental per- Not applicable. spective but also from an applied point of view. Ethics approval and consent to participate Conclusion Not applicable. Te importance of water-focussed research is expected Funding to further increase in the next years: changes in climate This project has generously been supported by a Project House of the Explora‑ tory Research Space (ERS) at RWTH Aachen University, as part of the German conditions as well as population growth will provoke an Excellence Initiative via the German Research Foundation (DFG) and the active confrontation with these topics to not only ensure Federal Ministry of Education and Research (BMBF). availability and quality of drinking water but also to pro- tect nature and human beings from water-borne events. Publisher’s Note Resource-preserving action is also required to protect Springer Nature remains neutral with regard to jurisdictional claims in pub‑ lished maps and institutional afliations. water bodies on one hand and to foster a rethinking in terms of energy production on the other hand. Te work Received: 9 January 2018 Accepted: 3 May 2018 of hydraulic engineering institutes—such as IWW—will contribute to these challenges by investigating related processes and developing efective tools and measures. References Abbreviations 1. Crawford SE, Cofalla C, Aumeier B et al (2017) Project house water: a novel BAW: Bundesanstalt für Wasserbau (Federal Waterways Engineering and interdisciplinary framework to assess the environmental and socioeco‑ Research Institute); BfG: Bundesanstalt für Gewässerkunde (The German nomic consequences of food-related impacts. Environ Sci Eur 29(1):23. Federal Institute of Hydrology); BMBF: Bundesministeriums für Bildung und https​://doi.org/10.1186/s1230​2-017-0121-1 Forschung (Federal Ministry of Education and Research); BWK: Bund der Ingenieure für Wasserwirtschaft, Abfallwirtschaft und Kulturbau e.V; DFG: Classen and Schüttrumpf Environ Sci Eur (2018) 30:18 Page 9 of 9

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