Δ-ENIGMA: The Dutch Delta on the Intensive-Care monitor Deltas and coastal plains are attractive places to live: fertile, flat, open to the sea. These lowlands are, however, also vulnerable to climate-change and sea-level rise. To better predict how deltas develop in the future we need a thorough understanding of how organisms, currents, waves, water&sand discharge shape the delta-landscape. This so-called biogeomorphology lies at the heart of Δ-ENIGMA, which provides infrastructure for intensive observational and experimental research of the Dutch Delta. This will improve our ability to predict future development, and help us live on happily in a changing Delta.

The NCR days are the annual scientific meeting of the Netherlands Centre for River studies (NCR). The NCR is a formal cooperation between several Dutch institutions, and its objective is to establish cooperation between the major knowledge suppliers and knowledge users in the Netherlands in the field of river studies. The ultimate aim is to reinforce the knowledge potential and thereby promote the international position of Dutch river research, and strengthen the education and scientific research at Dutch universities, to better design and manage Dutch rivers.

Since the Industrial Revolution humans have increasingly altered the composition of the atmosphere by emitting carbon dioxide, aerosol particles and trace gases. This has fundamentally changed atmospheric processes on many levels, but we do not yet fully understand how these emissions modify weather patterns, climate and air quality. The atmospheric system is complex and dynamic. Dust particles modify cloud systems, influencing precipitation, the transfer of radiation, and thereby the productivity of vegetation. Vegetation in turn alters the moisture input to the atmosphere and greenhouse gas concentrations, coupling back to atmospheric radiation. Cities accumulate heat and are hotspots of air pollution. Changes in atmospheric composition impact the atmosphere on various time scales. Greenhouse gases modify the radiative properties of the Earth’s atmosphere, heating our climate. Aerosol particle act more locally, reflecting solar radiation and modifying cloud properties. We have at present no adequate understanding of how the atmosphere might evolve in the future. The weather forecast is limited to days – partly due to the chaotic nature of weather itself – but also because we lack sufficient insight into the chemistry and physics of small scale processes and how they are coupled to larger scale phenomena in the atmosphere. Apart from the daily weather forecast, we also need to know the long-term trends of mean weather, its variability and its extremes. How is the changing atmosphere affecting our climate, and consequently: our living environment? The science to address these issues requires data at different spatial and temporal scales in different environments, ranging from urban centres to forests or grass lands. With the increasing availability of computational power and observational tools the atmospheric community is now at the brink of a new revolution. With the coupling of large flows of detailed observations to atmospheric models and simulations we are getting close to the realm of first principles: characterizing and predicting the state of the atmosphere based on the laws of nature with a minimized need for approximations of small scale phenomena. Atmospheric science encompasses many different disciplines from weather prediction to climatology, from air quality and greenhouse gas budgets to water cycle research and large-scale circulation. However, important breakthroughs in the most pressing scientific questions in many of these diverse disciplines require similar methodological advances: • long-term detailed observations of coupled land-atmosphere processes, • integrating micro- and macroscopic scales using observations (from microphysical observations to large scale measurements) and models (from cloud resolving to global models). The Ruisdael Observatory will provide the facilities to meet this goal. It will be operational in rural and urban areas to investigate the interaction between heterogeneous (urban) landscapes and the atmosphere. Observations and models will be merged in real time, integrating a wide range of spatial and temporal scales, to form a virtual laboratory for studying multi-scale processes in atmospheric chemistry and physics, and by doing so improve the accuracy of climate, weather and air quality models. These key advances will lead to • new knowledge of fundamental processes, such as the aerosol-cloud-turbulence interaction and land-atmosphere coupling in a heterogeneous setting, which will further allow to • develop an accurate representation of small-scale variability of atmospheric processes in climate, weather and air quality models, advancing our understanding of some of the most pressing challenges in atmospheric science: • attribution of the spatial and temporal variability of greenhouse and other trace gases to sources and sinks • enhanced understanding, detection, and prediction of climate and weather extremes We will create an unprecedented three-dimensional picture of the great “skies over Holland”, pioneered in canvas and paint by the famous 17th-century artist Jacob Ruisdael, and study the atmospheric processes using a combination of advanced sensors and high-resolution models. The location of Ruisdael Observatory – in a coastal climate and amidst major European industrial areas and cities - implies that a large variety of air masses and weather types are available for research. The Dutch landscape and human activities in it are well documented and intensively monitored. This unique combination of features makes the Ruisdael Observatory particularly attractive to international researchers working on improvement of both observational capabilities and modelling tools for climate change predictions for regions around the world. This will give us the novel insights we need to understand the atmosphere of today, predict that of tomorrow and of the decades to come. The Ruisdael Observatory is an integral part of the ESFRI infrastructures ICOS and ACTRIS in Europe, and will be associated to the US ARM network and program.

India and The Netherlands both face increasing flood and drought risks due to urbanization and climate change, while current water disaster management strategies are inadequate. This project aims to develop the knowledge and tools to mitigate future water disasters through an integrated understanding and multi-scale modeling of droughts and floods. Remote sensing, artificial intelligence, and machine learning are used to improve predictions. Socio-economic impacts will be assessed, adaptation measures co-created with stakeholder input, and guidelines provided to decision-makers. Study sites will demonstrate new approaches to disaster management and support acceleration and replication through knowledge sharing and peer learning.