Biological Responses to Physical-chemical Pressures in River-coastal Basins – (Ph.D.)

We build and apply conceptual and mathematical models in cooperation with laboratory and field experts. Our students are trained to become professionals in research, management and consultancy on environmental, nature and water issues. As we are both interested in and dedicated to solving environmental problems, we develop scientific knowledge and implement it in society. The research is organized in 4 main themes:

Theme 1: Reconstruction and pollution in the Rhine-Meuse basin
Western Europe in general, and the Rhine and Meuse delta in particular, have changed dramatically in the last centuries. In the past, this area consisted of natural wetlands with rivers that transported water freely from the land to the sea. Nowadays, land is intensively cultivated, heavily industrialized, densely populated, and consequently protected against flooding by dikes and dams. As a result of land use changes and high water levels, possibly enforced by climate changes in the future, the whole basin is under reconstruction. Dikes are raised and moved, summer and winter beds are excavated, obstacles are removed and emergency spillways are created. Reconstruction changes the flow of water and the level and type of the substrate altering the species composition and ecosystem functioning. Emissions of toxicants and nutrients from agriculture, industry and households cause pollution of water, sediment and air, leading to concentrations that affect plants, animals and man. Traditional pollutants are banned but new, largely unknown, chemicals are used and released instead. Nijmegen is located at a narrow of the rivers Rhine and Meuse, between the large German and Belgian catchments areas and the Dutch delta.As a consequence, problems throughout the whole basin are magnified in the vicinity of Nijmegen, giving good opportunities for research and education. Transitions between dry and wet, fresh and salt, pristine and heavily modified systems are nearby for detailed case studies. Students find a broad set of environmental, nature and water issues to learn from.

Theme 2: Conceptual and mathematical models to integrate fragmented data from lab and field studies
While the above-mentioned problems are inherently complex, information needed to derive solutions is scattered. Data are collected by various disciplines, in laboratory experiments and field surveys, carried out at different conditions, measuring different physical-chemical pressures and biological responses. To allow diagnosis and prognosis, coherent frameworks are indispensible. We therefore focus on the development and application of conceptual and mathematical models and databases that allow: (1) scattered information to become consistent knowledge, (2) qualitative judgements to be replaced by quantitative assessments, (3) causes to be linked mechanistically to consequences, (4) understanding to be followed by predicting. The models are in between an exact and an abstract description of reality. They should be sufficiently abstract to allow application to many cases and at the same time allow calibration and validation with data. The data needed are often collected in collaboration with other departments and organizations. In research, it allows modelling, laboratory and field experts to help each other. In education, students get the opportunity to link their own case studies to issues that they will have to deal with in their working life later. Examples of these models include BIOSAFE, USES-LCA and OMEGA.

Theme 3: Applied research from science to management
We are both curious about and commited to investigate solutions to environmental problems. Our efforts are therefore not only directed to developing scientific knowledge. We collaborate closely with organizations for environmental, nature and water management in the field of both physical and social sciences (see partners). In our assessment of environmental and ecological indicators, we include society-oriented aspects such as the perception of nature by people and the restrictions imposed by EU-directives. So far, management has been able to solve easy problems by reacting afterwards. Our models will help to anticipate and solve problems of a more complex nature.