SD/CL/03 SUDEMCLL.

Impact of climate change on river hydrology and ecology: A case study for interdisciplinary policy oriented research by: Prof. Patrick Meire, Universiteit Antwerpen - Ecosystem Management Research Group Prof. Patrick Willems, K.U.Leuven Hydraulics Section Prof. Jean-Pascal van Ypersele, Université Catholique de Louvain. Institut dAstronomie et Géophysique G Lemaître The impact of climate change on river hydrology and ecology is a subject that receives increasing attention and has strong implication for hydrological, ecological, economic and social policy. Because climate change affects such wide variety of disciplines, pursuing research in this field requires an interdisciplinary approach. This need to simultaneously understand and project the climate change, and to project and effectively deal with its impacts on the present and future aquatic ecosystem, presents a great challenge to the global research community. Climatologic research is very important for climate prediction, since knowledge of climate, including its statistical structure in space and time, is of importance to the environment. Only a modest change in the average of temperature or precipitation may imply changes in the statistical distribution of extremes and its consequences on the ecosystem. One of the variables of main interest is the chemical river water quality. It is a function of the chemical load applied to the river, the water temperature, and the volume of flow. Changes in the intensity, duration and frequency of rainfall events can alter paved runoff contribution, nutrient leaching and the occurrence of sewage overflow events. Therefore changes in river flows may alter the oxygen levels, organic pollutant and nutrient loads which are primary factors for species composition and biodiversity in aquatic ecosystems (especially fish population). Furthermore, altered flood regimes by changes in river flow regimes can also have impacts on the species composition and biodiversity of river valley and floodplain habitats. In the framework of the ADAPT project and in synergy with CCI-HYDR project, the impact of flood scenarios (frequency, duration, water height and season) on floodplain vegetation communities (habitats) and aquatic ecosystem is already under investigation with application to the ecological impacts. However, due to focus, time and budget limitations, the water quality of flooded water is not considered in details in the work plan of these projects. From the literature survey and from the first results of the ecological impacts, it was found that the absence of water quality information seriously hampered the impact assessment of certain changes in flood regimes. This also came forward in the questions raised by the audience during the Kick-off meeting of the BelSPO SSD projects on 26 March 2007 in Brussels. Furthermore, when integrating climatologic, hydrologic and ecologic information a lot of discussions emerge regarding the adequate space and time scales, use of indicators, environment friendly adaptations measures. There is a clear gap between what climatologists offer to the impact research community (in terms of variables and scales), and the starting point of the hydrological impact research, as well as the variables and demands by the ecological impact researchers. Experience in the CCI-HYDR and ADAPT projects indicated a need of communication and mutual understanding of offers and demands between the three disciplines. The interdisciplinary focus of the on-going research projects remains too limited. ADAPT brings together experts from hydrologic, sociologic, economic and ecologic research communities. The CCI-HYDR project brings together experts from hydrological and hydroclimatological research communities. The ABC Impacts project deals with impacts of aviation on climate, in particular at the regional scale over Europe, while the ASTER project focuses on long term climatological change at the global scale. However while it is important to understand sources and magnitudes of climate change uncertainty, there is also need to understand how and in what form policy makers can deal with uncertainties. The question arising here is how to address in both communication and decision making the uncertainties associated with regional climate change projections. The aim of this research is bringing together key experts from the climatological, hydrological and ecological research communities, as well as water managers and policy makers, in order to improve the decision making regarding the impact of climate change on aquatic and floodplain ecosystems. The first aim is to discuss relevant research issues in an open, interdisciplinary team. The focus on a case study Nete will allow us to adapt these relevant issues, while focusing on the combined information from climate projections (e.g. from the RCM simulation results from the EU PRUDENCE and ENSEMBLE projects, the CLM model run at UCL within ABC Impacts, or GCM results made available by the IPCC), changes in flow regimes (CCI-HYDR project), associated water quality (limited focus in CCI-HYDR project), and ecology/biodiversity (limited focus in ADAPT), with the final aim to allow far better projections of habitat quality and diversity. The objectives of this cluster project are: take stock of what is known in pertinent fields and identify the connections between them; foster communication across the disciplinary and academic lines that divide us so as to push forward the research to an efficient and fruitful ways; based on the case study specific focus, delineate the state-of-the-art from which we then can develop both a research and action agenda within the context of climate change in Belgium, with a view on assessing other impacted sectors; asses the impact of climate change on the aquatic river valley and floodplains biodiversity; integration of technical outcomes in subbasin management policy and plans.

Keywords:Ecology, Hydrology, Climate change impact

Disciplines:Geology, Aquatic sciences, challenges and pollution, Physical geography and environmental geoscience, Construction engineering, Earthquake engineering, Geotechnical and environmental engineering, Water engineering, Wind engineering