Please describe your professional (and/or personal) experience relating to water and space technologies.

For people who, like me, come from a region of the world where rain is seen more as a nuisance than a benefit, the importance of water is often rather secondary. For a long time, I took it for granted that clean drinking water was always and everywhere available and that neither agriculture nor forestry had to struggle with drought. Although experienced as a child and thus not yet aware of its impact, summers with extreme temperatures like 2003, especially in Western and Central Europe, made the abstract concept of water shortage a reality in traditionally water-abundant countries like Austria for me the first time. As years went by and the discussion about climate change and environmental destruction became increasingly intense, I started to realize that many of the things I had taken for granted growing up with would no longer exist in the near future, or had never existed for other people.

It was during the same period in which my awareness of the immanent importance of water resources has developed, that I began to become enthusiastic about everything that has to do with space and space travel. I suppose this was initially a child's enthusiasm, but in the second semester of my geography studies at the latest, I realized that space technologies - especially remote sensing - could be used to explore many of the pressing topics I had been keen to explore deeper. So I started to learn the methods of remote sensing (especially optical sensors, but also Radar and Lidar). Due to my passion for coding, which also started during this time, I was able to participate in research projects that used remote sensing methods to study the effects of global change on ecosystems and especially water availability. This allowed me to contribute my personal interest and skills to work on important issues such as sustainable development in agriculture, food security and hydrology.

Are you curious where my enthusiasm for space technologies and water comes from?

It may sound idealistic, but I think the biggest challenges of the future will be to maintain our groundwater aquifers, inland waters and oceans as intact ecosystems, and space technologies - especially remote sensing - will play a key role. Only remote sensing allows the standardized acquisition of data in repeated time intervals for large areas up to a global scale, which can be transformed into information using sophisticated algorithms. Especially the algorithmic part is an essential part of my work as a programmer. I am especially interested in the transfer of machine learning methods, since the statistical models used there, together with our physical process understanding, allow for an ever more precise investigation of the ever-growing data streams in ever shorter time.

At this point, it is important for me to mention that I adhere to the conviction that technology should never represent the goal alone but should always serve a specific purpose. In the case of water, it is not only a matter of understanding, mapping and quantifying water as a resource, but also of better understanding the forms and processes of water on Earth using these technologies in order to enable sustainable management.

How can space contribute to water resource management, hydrology or any water related field?

The global water cycle is a complex part of the Earth system and includes the cryosphere, atmosphere, oceans and inland waters, soils and vegetation. It thus encompasses all aggregate states of water and includes processes on various spatial and temporal scales. Space technologies can be used both to record the status quo and to deepen the understanding of the processes of the water cycle. Examples include meteorological remote sensing to map global weather patterns and atmospheric water vapour flows, or observing the oceans, where differences in the colour of water are an important factor. On land surfaces, optical, thermal and RADAR sensors can detect e.g. plant populations and can determine their mass and energy flows which relates to water evaporation and retention rates.

By coupling space-borne systems with in-situ measurements and physical models of the Earth system, changes in water quality, quantity and availability can be modelled on a global to local scale with high temporal resolution. By using open-access satellite data such as the American Landsat programme or the European Earth Observation Programme Copernicus the establishment of transparent and reproducible workflows and services becomes a realistic ambition. In addition to the "classical" water disciplines (e.g., hydrology, hydro-geology, oceanography, and meteorology), areas such as economics, urban planning and social sciences also benefit from these services. The reason for the potential benefits of space technologies in so many other sectors or research disciplines results from the sectoral and interdisciplinary influence of global water flows, since neither economic production nor living conditions are decoupled from the availability of water. Concepts such as "virtual water", which includes water used for the production and transformation of goods, can also be implemented operationally.

A very important step towards sustainable use of water resources is to understand two aspects: On the one hand, it must be clear how many water resources are available in a region and what role they play, for example, in ecosystem services. On the other hand, the water demand - e.g. from urban areas, industry and agriculture - must be known. For both aspects, space technologies offer a wide range of possibilities for the timely recording and presentation of spatio-temporal patterns. With this information well-informed decisions on water resource management can be made (decision making support) and the management metrics can be continuously monitored.

How does space technology contribute to water related aspects of the SDGs? Provide example(s) from your community and experience, preferably related, but not limited to SDG 6.

An essential concept for recording global water flows, not only at the hydrological level, is the concept of "virtual water". This is the amount of water required for the production of economic goods and food. In the mining of rare earths, for example, which are needed for the production of semiconductors, large quantities of water are required to extract the ores from the rock. If semiconductors are installed on a chip for a smartphone, the water used for this is allocated to the virtual water budget of the product (i.e. smartphone).
In the ViWA research project, in which I was involved in land surface time series modelling of vegetation, the global fluxes of water in agriculture are being investigated. The project didn’t only deal with quantifying water flows, but also addressed the efficiency and sustainability of water use in agricultural production. One example is the production of beef, which requires a very high amount of virtual water. In regions where renewable water resources are available in such large quantities that this water demand can be met without causing deficits elsewhere, the rearing of cattle for meat production can be sustainable, but in regions with water shortages it is unlikely to be. Therefore, the geography of virtual water plays an important role, which has not yet been sufficiently researched. Of course, such an approach can only be successful if, in addition to the natural science perspective, the economy and sociology are also taken into account. Such studies can also only be successful if there is a comprehensive data basis with repeated and repeatable measurements: space technologies, in which optical remote sensing and physical modelling in particular play an important role.

Another project was the research on gold mining in Ghana and its impact on water quality in rural areas using satellite data, carried out within the "Regional Academy on the United Nations" (RAUN). An analysis of freely available data and algorithms revealed a major challenge that has so far hindered the use of space technologies in developing countries: On the one hand, countries in the global South often lack the scientific data and surveys for the calibration and validation of workflows based on space technologies, and on the other hand, bureaucracy and contradictory policies hinder the effective use of the tools mentioned above. In the course of our research, we were able to show that technology alone does not guarantee a more sustainable use and management of water resources, although potential was identified in discussions with experts in research and application. For example, the co-founder of the oxeo start-up, Lucas Kruitwagen (personal communication), recently told me that there is great interest on the part of financial service providers in the risks of mining activities with regard to water availability and quality. This is due to sustainability constraints that are becoming increasingly important for portfolio managers.

While the previous two projects had a strong direct relation to water, my research activities in the MedHycon project focused on the quantification of sediment flows in Mediterranean catchments, which is important for sustainable settlement development and soil conservation. Thus, SDG #6 as well as SDGs 11 and 15 were addressed at least indirectly within the research. In my master thesis I am trying to map irrigation centre pivots in different geographical regions characterised by water shortage and to make statements about their irrigation status by means of means of deep learning and Sentinel-2 data. The resulting algorithm could be potentially used to map irrigated agricultural areas on a continental scale (e.g. Africa). This will allow better estimation of water demand and water availability, as well as estimation of current and potential water use conflicts. The same applies to a multi-temporal approach for estimating the increase or decrease in irrigation. This could be an important indicator for large-scale land grappling, since large-scale irrigation practices are usually not practised by local communities, but by large agricultural conglomerates characterized by foreign direct subsidies and multilateral economic and ownership structures.

How could these examples be built upon and expanded in the future?

Many of the studies presented are approaches for a later large-scale operational application, which for example are conceivable for the monitoring of policy implementation or can contribute directly to SDG #6 or SDG #2 (in agriculture and food security). It is important to note that while the technologies as such offer great potential, the technology should never be an end in itself, but should always be embedded in larger frameworks. These frameworks should reflect the realities of stakeholders' lives and provide relevant information in an understandable and accessible form. This is currently a major challenge, to be met by means of a more intensive, mutual transfer from science to society and policy making.

On the technological side, the approaches described above will certainly increasingly rely on methods of machine and deep learning, as the amount of available data is growing exponentially, and conventional methods are reaching their limits. I see great potential for artificial intelligence, especially in data related to the control and management of (virtual) water resources, which can detect irregularities in water flows early and trigger alerts. Thus, an early detection of water shortages such as misuse of resources (or their pollution) becomes visible. A further component will be the integrated use of various space technologies, such as the fusion of optical and radar data or the integration of satellite-based measurements of the earth's gravity field.

On the scientific side, interdisciplinary approaches should be deepened since virtual water resources cannot be investigated otherwise. However, this requires platforms of mutual exchange and harmonization efforts so that scientists from different disciplines can communicate with each other and share their results in a usable form. The same applies to the transfer from and into society, such as the mutual dialogue with stakeholders, which has so far been conducted only marginally in many projects, but should definitely be given more importance.

How would your ideal working environment look like?

I personally always take a somewhat critical view of the term "ideal", since an ideal state implies that no more changes are necessary, since everything already corresponds to the final objectives. However, I think that these objectives - whether on a personal or social level - are always changing and are subject to a constant process of negotiation. Therefore, I do not like to talk about ideal working conditions or a working environment, but rather wish that my working environment would enable me to approach these changing objectives. It is therefore important to me to have the personal freedom to try things out without pressure to succeed or expectations, and to discuss concepts such as results critically. To this end, I find it important to deal with colleagues and mentors at eye level. Also, the passing on of knowledge and the critical reflection of it is very important for me since it helped me a lot during my studies to steadily question observations and theories and kept me open-minded.

How could space technology benefit the WASH sector (groundwater detection is the most common approach, do any other examples, ideas, approaches come to your mind)?

The WASH sector stands like no other for the importance of SDG #6, which makes the contribution of space technologies in this area the more important: Personally, I see much more potential in this contribution than just the detection of groundwater resources or the mapping of surface water. Especially the quality - and not only the quantity - of water seems to me to be an important field of application for space technologies, whereby optical remote sensing in particular seems promising. On the one hand, the water quality indicators derived from it can provide an assessment of whether water from rivers or lakes can be drunk without health risks. On the other hand, remote sensing can be used to determine the effectiveness of wastewater treatment - for example in sewage treatment plants. Moreover, remote sensing offers the possibility of integrated monitoring with high spatiotemporal resolution. Thus, for example, the effectiveness and implementation of wastewater policies can be constantly assessed and a valuable contribution to the monitoring of water pollution can be made.

By means of this approach it seems to be possible to limit or even identify the polluters. In addition, in-situ probes can be sampled more precisely using the information gained from remote sensing and can help to deploy limited monetary and human resources at critical points. Thus, several contributions can be made to the WASH sector at the same time. Although, it must be clear, that remote sensing alone is not sufficient to cover all aspects - it is only a tool to make certain things visible and monitor them.

Machine learning has great potential for the processing of satellite imagery and generation of knowledge derived from space technologies. A common problem of professionals researching water is missing training and verification data. What do you think is missing in order to collect and share in-situ data on water bodies?

With regard to inland waters, data on water quality is certainly the greatest challenge: Various indicators (e.g. turbidity) can be derived from satellite data, but calibration and validation of the models used is often not possible on an aerial basis due to a lack of in-situ reference data. Both, the high spatiotemporal variability of water quality indicators and the high costs associated with measurement campaigns for sure are among the challenges leading to a lack of in-situ water quality data.

Another important point is the determination of the optical depth of water, i.e. to determine where the ground of a water body is still visible. In these areas, where the water is so shallow that the bottom is visible, it is actually not possible to make any statements about the water quality, because the spectral signature of the water column cannot be separated from that of the ground. The optical depth of the water itself can only be determined with high accuracy in-situ measurements and thus requires extensive mapping. Here too, temporal variations such as changes in shorelines as a result of floods and low water pose a further challenge.

In my opinion, it is not so much a lack of monetary or human capacity, but rather due to the complexity of water bodies and aquatic ecosystems that many in-situ data are missing or not available in the required resolution. I therefore think that the (further) development of physical models based on open-source software should be prioritized.

What do you consider as the biggest challenge in international collaboration on water?

Inland waters and oceans do not know about administrative borders or national affiliations. Many river basins comprise several states and a large part of the oceans are considered international waters. Ultimately, I see the biggest challenge in two main points: On the research side, while there is an awareness of the need for integrative approaches to studies based on natural units, such as catchments, this awareness is not always reflected in research funding. National donors have a justified interest in research on their own waters, but often do not take into account the natural spatial relationships, which can extend far beyond their own national territory. Global studies, on the other hand, which overcome this limitation, often have too low spatial or temporal resolution to provide accurate, relevant information for decision makers in individual smaller hydrological units. Therefore, I see the intertwining of regional and global approaches in research with appropriate funding as the first challenge.

The second challenge is closely related to the first one: This concerns legislation, which includes many things like water rights and regulations for the use of inland waters and oceans but is also limited to national entities in many cases. In my opinion, there is a need for more international agreements and minimum standards, which should be incorporated into national legislation in the form of laws. Institutions would then also be necessary to comply with these agreements at a higher, international level. For international waters, I also see the need to strengthen the existing institutions in order to ensure a sustainable use of these waters. At this point, political will is crucial, but examples such as the Water Framework Directive of the European Union show that agreements at the multinational level are possible.

As a young professional, what do you feel is missing in the current scientific debate and management of water resources?

Research projects often provide important findings, but too often I do not see the step of deriving relevant, lasting initiatives from scientific approaches currently receiving sufficient attention. A project that leads to virtually no action after the end of the funding period is usually of little relevance for decision making and monitoring, as the scales of the global water balance and trade in water resources are not limited to finite time periods. For example, changes in water management schemes have long-term effects, but these are often not immediately visible. I therefore see the problem that many projects produce very promising show cases, but the decisive step towards operational services and continuous development and use is often missing. Scientific papers are important means of communication - but who are the actors to pick up scientific publications and enter a dialogue with stakeholders? What is left, is often very little relevance for the management of water resources, and finally for society. In my opinion, research projects must therefore focus much more on public relations work and present the results in an open and generally understandable way. This should also make it easier to reach sections of society that have hitherto been little informed by science, and knowledge about the management of water resources and the use of space technologies should not be reserved for a privileged (expert) group.

Furthermore, I often see a strong conceptual and substantive decoupling of natural and social science approaches. In my opinion, this is another point which, although discussed in the scientific debate under the concept of trans- and interdisciplinarity, too often does not provide any tangible output in terms of genuine interdisciplinary research in relation to water. The term "space technologies" also indicates that the technological aspect comes first, although I firmly believe that technology alone has little value.

What do you need to innovate?

Innovation is not necessarily synonymous with progress, but I can think of one important point in which innovation, or let’s say progress is definitely needed. It is about the energy and resource consumption of IT infrastructure needed for the analysis of remote sensing data. It is only a recent development that the energy requirements of servers and data centres have become a matter of public awareness, and we have only started to break down the resource requirements of chips or other components have. Currently, I would say, hardly any IT system can be called sustainable, because the demand for energy and non-renewable resources is far too high. Thus, it is ironic that the very same IT that enables us to address many of the challenges of sustainable development, itself is diametrically opposed to sustainability.

Therefore, I see a great and urgent need for so-called "green IT", i.e. more sustainable hardware and software solutions - not only in the field of space technologies. We urgently need innovation that leads to a reduction of the need for resources, enable more recycling and place greater emphasis on ecological and social aspects. Being a software developer, these also affect me personally.

How do you keep abreast the fast-paced developments (image processing and machine learning, space technologies, natural resource management, what did I miss)? Would you share your secret with other young professionals?

I think there is no special secret how to keep up with the fast-paced developments that we currently experience in many topics related to space technologies, algorithms, and research in general. It very important for me that the topics my work is concerned with somehow match my personnel interests. Thus, I have the willingness to learn new tools and rethink traded workflows and research paradigms. Not because I have to, but because I want to. This intrinsic rather than extrinsic motivation makes me denote a fairly large portion of my time to learning and discussing these developments. I really enjoy reading about advances in scientific studies, checking out new software and discussing with peers about data, workflows, theories, and concepts.

Usually, I do not restrict myself to any specific topic or discipline. I also enjoy reading books about history, the development of human societies and languages or books about astrophysics. The point I would like to make here is about my personal necessity not only to study articles, books and reviews which concern my professional topics but also to read about completely different things. I think this helps me a lot to keep open-minded and to critically reflect developments and innovations made within those disciplines I am most familiar with. Since these fast-paced developments already imply that is hard to keep up-to-date all the time, it is even more important to have the ability to critically reflect about these developments as development alone not necessarily leads to progress in terms of sustainability.

Last, one very personal hint: Life is not only about studying and working! Spending time with friends and family, doing sports and even doing absolutely nothing are – in my opinion – the most valuable source of inspiration and creativity.

What do you see as key areas for capacity-building in developing countries and least developed countries with regards to space technologies for water management and in which areas do you see the greatest potential of the generation of young professionals?

A very first point is about raising awareness – not only about emerging global problems with local impacts but also about the value of traded knowledge and practices. While many traditional small-scale societies had a very profound understanding of the importance of local water sources and developed life styles that sustained their way of living for many decades or even hundreds of years, the process of what is often called “westernisation” lead to abandon traditional cultivation measures and practices. My point here is not to idealize these societies, but as the famous geographer Jared Diamond emphasized, there is a lot we can learn today from our ancestors and those societies still maintaining traditional lives. Thus, I think it is essential to raise the awareness about the importance of traditional knowledge (which is often endangered) and local environmental, economic and social problems. At this point it is important to build capacity that not only involves local communities but also builds upon their traded knowledge and experiences. Of course, this aspect not only holds true in developing countries but especially in these parts of the world where societal and economic pattern changed rapidly over the last decades with unpredictable consequences for local livelihoods and ecosystems.

Second, education of girls and boys and equal access to educational resources and the possibility to learn (and practice) a profession or study at the university are essential milestones for acquiring new talents for the space and water sectors from these countries. Currently, I think that the space sector is dominated by players from western countries and China, but I also see a lot of promising prospects arising in western Africa (especially Ghana and Nigeria) where governmental and private initiatives show an impressing incentive to use space technologies for water related topics. To let these initiatives grow and generate lasting impacts researchers, engineers and developers are required. Sharing knowledge in a reciprocal manner with these young professionals is therefore another essential bullet item of capacity building. For me as a young professional from the West I see a great potential in here not only to share my own knowledge and experiences but also to learn from peers from these countries and to better understand their way of solving problems and generating development and progress.

Past generations of researchers and professionals often saw the need to bring tools and methods to developing countries or advised local communities to act in a specific manner. Nowadays, I hope that we can overcome this (post-)colonial way of thinking and work in a respectful, reciprocal way where the flow of knowledge is not only aligned in one direction and the value of local knowledge is not constantly undervalued.

Last, but not least, what is your favourite aggregate state of water?

As a natural scientist, the triple point of water is very interesting for me: at this point, all three phases (i.e. solid, liquid and gaseous) exist in thermodynamic equilibrium.  However, even slight changes in pressure or temperature are sufficient for the water to assume one of the three states. At the triple point, the amazing mutability of the chemical compound water is most impressively demonstrated.