Ana Margarida Bento, Editor of Newsflash Europe interviews  Vice Chair of IAHR Regional Division of Europe Prof. Anastasios I. Stamou, National Technical University of Athens (NTUA) in Greece and Keynote Speaker at the 8th IAHR Europe Congress.

The interview of Professor Stamou navigates hydro-environmental research and climate change adaptation in water infrastructure, revealing critical insights. He highlights acute climate hazards such as precipitation shifts, floods and wildfires, and underlines the importance of the European Commission's guidelines for climate-proofing infrastructure. The proposed Climate Risk and Vulnerability Assessment (CRVA) methodology outlines key steps in vulnerability assessment and adaptation. It advocates Computational Fluid Dynamics (CFD) modeling as a key tool for understanding climate impacts and optimizing design, with applications ranging from wastewater treatment plants to flood studies. The discourse compares CFD models with General Circulation Models (GCMs) and addresses the challenges of infrastructure adaptation. It highlights international collaborations such as the TRITON project, outlines policy recommendations and emerging trends, and advocates interdisciplinary solutions to combat climate change in water management.

Can you give us an overview of your keynote presentation on "Hydro-environmental research on climate change adaptation of water infrastructure"?

The presentation deals with the hydro-environmental research that is relevant to the adaptation of water infrastructure, which encompasses drinking water, wastewater, and stormwater to climate change. Water infrastructure is one of the most important sectors of critical infrastructure; it is vulnerable to acute climate change hazards, such as precipitation decrease and droughts, increased frequency of heavy precipitation events and river floods, storm surges, coastal floods and erosion, extreme winds, landslides and sediment erosion, wildfires, and heat waves, as well to chronic hazards, such as temperature increase and sea level rise. These hazards that can disrupt the functionality of water infrastructure are expected to intensify during the 21st century.

Aiming at fostering the development of resilient, climate-proof infrastructure, the European Commission released in 2021 the Technical Guidelines on “Climate-proofing Infrastructure” for the period 2021-2027. These guidelines, which incorporate both climate change mitigation and adaptation strategies and mainstream climate considerations in future investment and development, are principally designed for project developers and experts involved in the infrastructure preparation. Additionally, they serve as a valuable resource for public agencies, implementation partners, investors, stakeholders, and others. Moreover, they unveil new research areas.

The presentation focuses on climate change adaptation. From now on, we must develop every important individual infrastructure project incorporating a methodology for its climate proofing that is practically a Climate Risk and Vulnerability Assessment (CRVA). Very recently, we published a paper entitled “Proposed Methodology for Climate Change Adaptation of Water Infrastructures in the Mediterranean Region”. In this paper we present (i) the development of a Climate Risk and Vulnerability Assessment (CVRA) methodology based on a literature survey and the relevant European Commission guidelines and (ii) its indicative application to a wastewater system in Greece. The relevant research work is part of the emblematic national research project CLIMPACT in Greece.

The proposed CRVA is structured around the following 5 key steps:

(1) Description of the specific water infrastructure under study, in which we identify its main components, the potential hazards and the corresponding indicators for each hazard.

(2) Climate change assessment that is based on appropriate climate change scenarios allowing for the projection and evaluation of potential future climatic and socio-economic conditions.

(3) Vulnerability assessment to pinpoint the potential significant hazards that may impact the water infrastructure; it comprises four analyses for exposure, sensitivity, adaptive capacity and vulnerability.

(4) Risk assessment to identify the significant hazards, which consists of the likelihood, the impacts and the risk analyses.

(5) Assessment of adaptation measures to manage the risks identified in the previous step and reduce them to acceptable level.

The presentation follows this CRVA procedure; for each of these steps indicative hydro-environmental research areas with examples are presented and suggestions for future research are discussed.

With your extensive experience in computational fluid dynamics (CFD) modelling, could you elaborate on how these models are being used to understand and address the impacts of climate change on water infrastructure?

CFD models solve the 3D conservation equations for fluid mass, momentum, energy, and scalar quantities, such as temperature, water quality and biological variables, using numerical methods and algorithms, to determine the fluid hydrodynamics and scalar behaviour in various flow problems. In water engineering, these problems refer mainly to water flows in natural water bodies, such as streams, rivers, and lakes, man-made water structures, such as channels and reservoirs, and water flows interacting with structures. Using CFD models we can investigate various design or operation scenarios of water structures to optimize their design or performance virtually, i.e. without implementing these scenarios in the real structures. Regarding climate change impacts, we use CFD models to investigate a series of climate change scenarios, to determine their effects on the behaviour of water structures.

Let me try to illustrate this difference with an example of the components of a wastewater treatment plant (WWTP).

Let us assume that we want to optimize the design of the inlet configuration of the secondary settling tanks of the WWTP. We may use a CFD model to determine the buoyant flow in these tanks due to temperature differences and design the inlet in order to minimize short circuiting and thus to achieve maximum solids removal efficiency. With the CFD model we can test several inlet configurations and based on the results to select the optimum. In climate change conditions, we may need to investigate the effect of the climate hazard “temperature increase” on these tanks. In this case, we perform CFD computations for the current and the “future” wastewater temperature to determine the efficiency of these tanks, to compare them and decide whether the effect of this climate hazard is significant or not. If we conclude that this effect is significant, then we need to adapt these tanks to this hazard, probably by modifying further the inlet configuration. Similarly, we can investigate the effect of the same hazard on the efficiency of the biochemical processes, such as in the aeration tanks of the WWTP, and if this is found to be significant to perform the required adaptation measures, such as to increase the capacity of the aeration system.

Also, we can apply CFD models to study the climate effects in water infrastructure that include structures, such as buildings. For example, if we need to consider the climate hazard “floods” in the case of a WWTP, we use a CFD model to determine the water depths and velocities in the inundated areas of the WWTP including the buildings, where equipment is installed. We perform CFD computations for the current and future design flood discharges, compare them and decide on the effect of the “floods hazard”; if this is significant, then we propose specific adaptation measures, such to raise the flood protection levees of the WWTP, to raise the ground elevation in specific areas of the WWTP or in the buildings to protect the equipment.

Moreover, as water engineers we may need to apply CFD models to determine the climate change impacts not only on water structures, but also on infrastructures that are affected by climate hazards, which are “water-related” to use the EU taxonomy, such as “floods” and “storms”. For example, we can perform CFD computations to determine the behaviour of an old bridge in a river during floods, i.e. for the hazard “floods”, and eventually propose measures to reduce the scour potential near the piers of the bridge, or to determine the protection of new buildings near the coast against future storms or tsunamis. In some of these cases, CFD models may need to be more complicated to describe accurately the water-structure interactions (FSI).

To summarize, CFD models are extremely useful tools to help us understanding and addressing the impacts of climate change on water infrastructure; we can use them to design new infrastructures or to modify the design of existing infrastructure to “be ready for climate change”.

In any case, CFD models in their most complex formulation, which are the General Circulation Models (GCMs), are used to simulate the response of global climate to the increasing greenhouse gas emission estimations. Luckily, in most of the water problems we expect to face, the CFD models are not that complicated and do not require that large computational resources.

What are some of the key challenges and complexities involved in adapting water infrastructure to a changing climate?

One of the most important challenges is to improve our ability to predict the changes of extreme whether events that are related to climate change and thus to reduce the associated uncertainly. For example, to design a stormwater infrastructure under climate change conditions, we need to know the design floods in the specific catchment area. To acquire this knowledge, we need to know how the projections of the GCMs after downscaling are linked to the observed extreme rainfalls in the specific area that we use in the design. Currently, this linkage is not well determined due to the high uncertainty in climate projections by different GCMs and downscaling approaches. Thus, we need innovative and more effective modelling approaches to describe the behaviour of extreme whether events at local scale, where the infrastructure of interest is sited.

The current lack of the proper design regulations and specifications of water infrastructure that consider climate change is certainly an important challenge. Nowadays, most of the relevant design norms and regulations do not specify the exact way, such as the methodology, engineers should consider climate change in the design of water infrastructure, but they state generally that climate change should be considered. The Technical Guidelines issued by the European Commission is a very important step on climate-proofing infrastructure; however, our knowledge on all adaptation aspects of water infrastructure is not sufficient and detailed. Thus, we need more detailed scientific and practical knowledge on the procedure of climate proofing of our water infrastructure, especially on aspects such as sensitivity and exposure assessment.

Often our traditional design and management of water infrastructures fail to meet the stakeholders’ expectations; sometimes we develop our water infrastructure too soon resulting in unnecessary and expensive irreversible investments, and sometimes we wait too long putting in danger the reliability of the infrastructure. This is due to the fact that we design and manage our water infrastructures assuming that the design and the management conditions are “steady state”; however, this is not true due to climate

change. Thus, we need to develop new methods for the adaptive design and management of our water infrastructure, for example using systems thinking and flexibility.

Your research covers a range of areas, including surface water pollution, thermal pollution, and dam brakes. How do these different aspects intersect in the context of climate change adaptation and resilience of water infrastructure?

The above-mentioned areas that are surface water pollution, thermal pollution and dam break are three important environmental impacts, which may be caused by a wastewater treatment plant (WWTP), a thermal power plant and a dam, respectively. Typically, these impacts are investigated during the design of these projects and more specifically during their Environmental Impact Study (EIS); they can be created due to their malfunction or failure due to various hazards, including climate hazards, such as floods.

One of the common features of this research was that in all cases we used numerical models to simulate the effect of potential failures. In the case of the WWTP we combined a simple hydrodynamic model with a water quality model involving a number of quality variables, in the thermal power plant we used an in-house layered coastal hydrodynamics model coupled with a temperature dispersion model and in the dam we performed computations combining a breach-model, a 1D hydrodynamic model for flood propagation in the mountainous region, and a 2D hydrodynamic model to describe the flow in the downstream potentially inundated area.

The research on these projects is connected to the first stage of the procedure for climate proofing that is climate change “mitigation”; then, it is followed by the second stage that is “adaptation”. To perform the adaptation of these infrastructure projects, we need to follow a CRVA procedure, like the one we discussed in the first question, and eventually use the same or similar mathematical models to determine the impacts of the most important climate hazards.

As Director of the Laboratory of Applied Hydraulics and Director of the Interdepartmental Master's Programme "Water Resources Science and Technology", what innovative approaches or strategies do you advocate for educating the next generation of water resources professionals on climate change?

Firstly, we need to inform and educate our students on climate change and its effects, for example via the modification of the curriculum of our programme. This is what we (the Management Committee of the Master's Programme "Water Resources Science and Technology") have performed in the years 2020-2022. We made the required updates of the Programme following a detailed report, which was formulated based on discussions in meetings with the tutors and the students; also, we took into account the proposals by consulting firms. We did not add new courses specifically for climate change, but we simply provided the main information of climate change in one of the prerequisite courses and included specific climate change aspects in our existing engineering courses, in which this was necessary and/or useful for the whole Programme.

We need to update our Master's Programmes when it is needed to adjust the content of their courses to the progress of water science and technology in the face of climate change; however, these need to be performed carefully and in an integrated way that takes into account all important factors and avoids the omission of the required basic knowledge that should be provided to our students. After all, we do not need to teach all our knowledge on climate change and climate uncertainly to our students. There are also other approaches to inform them, for example via invited lectures, seminars by experts, study projects and theses.

The regular and careful update of our Master’s Programmes is not the sole strategy; it should be accompanied by other education activities, such as the ones mentioned before, as well as via the internationalization of the Programme and the proper teaching methods.

The internationalization of our Programmes is very important. During the period of the recent update of our Programme, we had a cooperation with the Technical University of Munich (TUM) within a DAAD project entitled “WaTer Resources Management for Climate Change AdapTatiON (TRITON)"; the objectives of TRITON were to extend the existing educational cooperation between TUM and NTUA, and to develop a Double Degree or 1-1 Programme in “Water Resources Management (WRM) for Climate Change Adaptation” that includes research focusing on “Flood Management in a Changing Climate" and cooperation with consulting firms from Germany and Greece. Within TRITON, we had performed several activities that can be applied in a modern Master’s Programme. These activities included the exchange of German and Greek graduates and young researchers, a Workshop, a Summer Course, and a Conference, exchange of short stays and guest lectures of TUM and NTUA professors, and the development and maintenance of webpage & e-learning platform. The Summer Course entitled “Nature Based Solutions to confront water extremes in Europe: design and modelling tools” was one of the pre-congress activities of the IAHR Europe Congress in Athens in 2022. We continue the cooperation NTUA-TUM via the Erasmus + programme that is an easy and efficient approach towards internationalization of Master’s Programmes.

Finally, teaching methods are decisive for the success of a Master’s Programme. We want our teaching methods to be effective; to achieve this, we encourage interactive teaching, teamwork and case-study learning, and project-oriented teaching. In some of our common NTUA-TUM courses we applied research-oriented teaching. This teaching method is described in one of our common publications entitled “How can we link teaching with research in our engineering courses? The case of an ecological modelling course in two European Universities”.

Could you share with us a specific case study or project where computational modelling has played a key role in informing climate change adaptation strategies for water infrastructure?

In one of our recent projects entitled “Assessment of Earthquake, Fire and Flood Risks in the District of Attica” financed by the Prefecture of Attica, we cooperated with two research groups from the National and Kapodistrian University of Athens and the National Observatory of Athens to study the implementation of Nature Based Solutions (NBS) to reduce flood risk in two river basins upstream of the historic town of Marathon in Attica.

NBS are very important for climate change adaptation. The European Environment Agency states “NBS for climate adaptation and disaster risk reduction can contribute to the EU nature restoration agenda. Applied at scale, they would enhance biodiversity in both urban and rural landscapes. Accelerating and scaling NBS across Europe is key to achieving EU policy targets”.

We proposed NBS that included the land use change of bushland area to forest land and the development of flood basins in the main streams and their floodplains. We applied a methodology using an integrated modelling approach in climate change conditions to determine the effects of the NBS. This methodology was based on the EU “Floods Directive” and included an innovative approach for vulnerability assessment for buildings.

The integrated model consisted of the hydrologic model HEC-HMS and the hydrodynamic model HEC-RAS 1D/2D. The effect of climate change in the integrated model was considered via calculations with GCMs for various scenarios to determine the design extreme rainfall. We used daily data from the state-of-the-art CMIP6 and EURO-CORDEX data covering the period 1971-2100, incorporating the new emission scenarios (Shared Socioeconomic Pathways) SSP2-4.5 and SSP5-8.5 for CMIP6 and RCPs 4.5 and 8.5 for EURO-CORDEX. Since the horizontal spatial resolution of CMIP6 models is at least 100 km, climate data of higher spatial resolution (of the order 1-9 km) were produced via statistical downscaling using the ERA5-Land reanalysis.

We performed calculations to determine the NBS effects under climate change on the peak flow rates and the flood volumes of the hydrographs, and the extent of the inundation areas, the maximum water depths and velocities, the flood hazard, and the flood risk in the main streets of the town of Marathon.

Given your involvement in numerous research projects and consulting activities, what are some of the key lessons learned or best practices identified in integrating scientific research into practical solutions for climate-resilient water management?

I believe that the close cooperation between academia and practicing engineers is of major importance. Our engineers face many practical problems dealing with the design, construction, and operation of water infrastructure. These problems require solutions using advanced and sometimes innovative methods, such as modern modelling tools, that are not common to engineers in consulting firms. Specialized and experienced researchers are familiar with the required technology; thus, they can solve these problems and then explain clearly to engineers the solution methods and their results. Usually, in this applied research, postgraduate students and young researchers are involved.

Moreover, teachers who are also researchers, need to communicate these problems to our students, the future water engineers, as part of their studies, in the form of case study teaching, project-based learning, research-oriented teaching, study projects and theses.

This academia-practicing engineers relationship bridge the gaps between engineering education and practice; it should be regular, continuous and at an international level, when this is feasible. It can be enhanced by common activities, including presentations of case-studies in conferences by both consulting engineers and academia, and organization of common meetings and workshops, where experiences can be exchanged.

Other activities include the organization of continuing education programmes or specialized seminars, where innovative methods are presented to practicing engineers, provision of scholarships for engineers in the public and private sector to participate in Master’s Programmes and invited lectures in conferences organized by consulting firms.

At this point, I would like to emphasize the importance of workshops in the adaptation procedure of infrastructures to climate change. More specifically, the step of risk assessment often involves the organization of “risk identification workshops” to identify hazards, consequences, and key climate-related risks. In these workshops, the opinion of experts, mainly practicing engineers, is extremely important.

For example, when we (researchers) want to assess the sensitivity of a WWTP, we analyse the relevant references and the characteristics of the specific WWTP and performed the sensitivity assessment at a preliminary level. However, this assessment needs to be detailed and complete; to achieve this it requires the experience of expert engineers, who design and operate WWTPS for every significant component of the WWTP. Very recently, a document was published by a well-known organization on the climate proofing of water infrastructure that describes a very useful and systematic methodology based on the Technical Guidelines of the European Commission. In this document the sensitivity of the WWTP is assessed in detail using 32 climate hazards, while the WWTP is practically considered as a single component infrastructure; thus, the assessment is not expected to be complete. This example shows clearly that the adaptation of our infrastructure to climate change requires the participation and cooperation of specialized engineers and other scientists of many disciplines.

Finally, the integration of scientific research into practical solutions requires its communication to all actors of water management, including politicians, government officials, organizations working in the water and climate sectors, NGOs, and the public, via activities including meetings, and simplified publications and presentations in the mass media.

How do you see the role of international collaboration and knowledge exchange in advancing research and innovation in water and environmental engineering, particularly in the context of climate change adaptation?

International collaboration itself can be a knowledge transfer strategy that supports innovation; it has been adopted by prestigious universities and research institutes that collaborate with each other via international projects to perform applied research. Often, this collaboration involves the active participation of the private sector, such as companies, which benefit from the results of these projects. Such projects include activities, such as consulting for companies, life-long learning, workshops, and webinars.

Frameworks that facilitate the mobilization of students among universities for studying and research purposes, such as the Erasmus+ programme, are also very important for knowledge exchange, especially for students and young researchers.

The number of international collaborations in water and environmental engineering, particularly in the context of climate change adaptation is continuously increasing. Nowadays, there are organized and integrated ways to streamline the dissemination and implementation of research and innovation activities globally, such as platforms and databases that are produced within international projects. CAKE and PLACARD are indicative examples of such projects. CAKE (Climate Adaptation Knowledge Exchange) is a joint project of the non-profit organization EcoAdapt and the publishing company Island Press; it is aimed at building a shared knowledge base for managing natural systems in the face of rapid climate change and it is intended to help build a community of practice. PLACARD (PLAtform for Climate Adaptation and Risk reDuction) is a platform for dialogue, knowledge exchange and collaboration between the Climate Change Adaptation and Disaster Risk Reduction communities. Both CAKE and PLACARD include valuable resources on climate adaptation case that are related to water infrastructure.

Based on your experience as Vice Dean of the School of Civil Engineering and your involvement in various professional bodies, what policy recommendations would you make to policy makers and stakeholders to enhance climate resilience in water infrastructure planning and management?

The most decisive policy makers in infrastructure planning and management are the governments, which formulate long-term development plans and regulations at national, sectoral, or municipal level, which impact the planning and implementation of climate-resilient infrastructure. These should address climate resilience in all critical infrastructure sectors, including water.

One of these frameworks is spatial planning, which should include climate resilience aspects. Also, it should be formulated in such a way to allow municipalities to account directly for climate change aspects. For example, a municipality should be able to decide to forbid the development of water infrastructure in areas, which are sensitive to climate hazards. In this way infrastructure adaptation is promoted at a municipal level.

Another two frameworks are the Strategic Environmental Assessment (SEA) and the Environmental Impact Assessment (EIA). The SEA assesses the extent to which a given policy, plan or programme provides an adequate response to environmental and climate change–related challenges, may adversely affect the environment and climate resilience, and offers opportunities to enhance the state of the environment and contribute to climate-resilient and low-carbon development. SEA gives recommendations at a strategic level and allows a better control over interactions or cumulative effects, while the EIA assesses the impacts on the environment of a project, such as an infrastructure. The Technical Guidelines on climate-proofing by the European Commission include recommendations for the integration of infrastructure climate proofing in the SEA and EIA during the stages of their design.

Technical codes, norms and standards are also of great importance. Traditionally, these focused on minimum requirements for the basic performance under normal operating conditions taking into account hazards, like earthquakes, wind and snow. Nowadays, these normal conditions are not valid, because climate change altered them. Thus, these codes should be updated to account for and promote climate resilience, including new climate hazards and multi-hazard assessment. These updates should be performed whenever it is needed by specialized Committees composed of community members and experts from the private sector and the academia. In this updating procedure, the relevant information produced by major international standardisation organisations, such as CEN that issues the Eurocodes, and ISO, should be taken into account.

The infrastructure policies and regulations set by governments often refer to aspects, such as the characteristics of the areas where infrastructure is developed, methods for the construction, operation, and management of this infrastructure, as well as its financial structures and revenues. These regulations should be followed by another important player that is the private sector, including infrastructure providers; thus, they should encourage the private sector’s efforts towards climate resilience and greater participation in the financing, operation and management of public infrastructure and services. Moreover, infrastructure providers should be encouraged to report on their exposure to climate risks. An interesting challenge is how to transform infrastructure’s climate risk information in financial terms to include it in its financial reporting systems.

One of the major deficiencies in many countries is the lack of high quality and consistent data that are required by decision makers, who can be the government themselves, the project developers, or the investors. These players need to know and evaluate the uncertainties, including these due to climate change, to take them into account in their decisions. Governments should develop open data platforms and online tools that can provide these data. In these activities the participation of academia can be very decisive.

Also, there are other players whose contribution towards climate resilience in water infrastructure planning and management can be significant, including national engineering associations, like ICE in the UK and ASCE in the USA, NGOs, the engineering community, and the public. It is important that data and information on water infrastructure planning and management are disclosed and reported to all relevant actors.

Looking ahead, what emerging trends or research directions do you foresee in the field of hydro-environmental research, and how can IAHR’s Committees and Congresses contribute to fostering interdisciplinary dialogue and collaboration in addressing global water challenges?

We address global water challenges via research that is generally driven by policies and decisions by our policy makers at different levels, such as at world level, EU level, or country level. Usually, these policies are influenced by goals that are set internationally at high-level, for example the 2030 Agenda for Sustainable Development and the Paris Agreement, such as the 17 Sustainable Development Goals (SDGs). One of the most important SDGs for water is SDG6 “Ensure access to water and sanitation for all”, while climate change undermines nearly all SDGs. SDG6 aims at safer drinking water, better water quality, better wastewater treatment, safer reuse, better water-use efficiency, adequate freshwater supply, integrated water resources management, protection and restoration of water-related ecosystems and others.

The emerging trends in hydro-environmental research aim at achieving these global water goals in an integrated way, considering links and relationships, for example the water-energy-food nexus, and the climate change hazard-infrastructure. In many cases, they combine innovative advanced modelling methods based on data science, such as AI and digital twins, with innovative technologies using new materials, such as membranes and nanotechnology.

Some of these research areas are: smart water management systems using data analytics, innovative sensors, machine learning algorithms and internet of things, efficient monitoring and early warning systems using AI and other data science tools, smart solutions and tools to improve infrastructure’s resilience to climate change, advanced technologies in water reuse and desalination combining innovative treatment methods and advanced modelling tools, such as machine learning and digital twins, habitat restoration via ecosystem based river management, innovative technologies for sustainable urban infrastructure, such as green and nature based infrastructure.

The IAHR members have specializations that cover practically all emerging research directions; one can very easily realize this by just looking at the Technical Committees, the Working Groups of Experts, the papers published in its journals and the publications in its Congresses, as well many other IAHR activities. Subsequently, the IAHR plays a very important role in performing and disseminating the research and other relevant activities that address global water challenges.

IAHR Congresses are very important hubs for knowledge exchange and motivation for innovation; thus, they contribute significantly to foster the interdisciplinary dialogue and international collaboration in addressing global water challenges. The papers presented in the IAHR Congresses are generally of very good quality and cover many general and specialized research areas, as shown in the general themes or key topics and the special sessions of the Congresses, respectively; the latter are often driven by the Technical Committees and/or the Working Groups.

Nowadays, there are research areas that are very interdisciplinary, such as the adaptation of water infrastructure to climate change, which is relevant to the subjects of most of the IAHR Technical Committees; moreover, it is of practical interest and requires interaction with all the actors involved in water infrastructure and climate change including decision makers. I believe that for such interdisciplinary and cutting-edge subjects a stronger cooperation and interaction between the Technical Committees of the IAHR is needed, as well as a high-level dissemination of the relevant applied research results, activities, and reports, such as the relevant IAHR’s white papers, in global forums.