The Host Organisation for the Middle Rhine Supersite will be the German Federal Waterways Engineering and Research Institute (BAW) at Karlsruhe, in collaboration with the Federal Institute of Hydrology (BfG, Koblenz).
The Rhine rises from two source rivers in the Gotthard massif at 2,344 m above sea level. The catchment area of around 185,000 km² comprises nine states and with a total length of about 1,233 km and a mean runoff of 2,300 m³/s at the German-Dutch border the Rhine is one of the largest rivers in Europe. From Basel to Rotterdam, over a distance of about 800 km, the Rhine is navigable. The Supersite Middle Rhine will cover the entire free-flowing section of the river in Germany, about 530 km from the last barrage at Iffezheim all the way to the Dutch border, where somewhat further downstream, it connects to the Rhine-Meuse-Delta Supersite, hosted preliminary by Deltares (Netherlands).
Throughout the 19th century the Rhine was subject to significant anthropogenic change, including river rectification and implementation of flood defences to increase cultivated land area and reduce the extension of inundated areas during floods. These measures significantly reduced the flow length of the main channel while, at the same time, confining its cross section. Consequently, these changes caused riverbed incision of up to >4 m within less than 100 years. The 20th century saw further substantial regulation of the Rhine. Upstream of Iffezheim a total of 10 barrages were constructed, primarily with the aim of hydropower generation. Downstream, the implementation of groynes and longitudinal works ensures the navigability of the stream to date. These regulations increased river bed incision even further during the 20th century, accelerating it about tenfold within the last 200 years. However, the Rhine is a bedload-deficient system, which requires permanent artificial gravel supply, totalling >350,000 m3 each year to mitigate the corresponding negative effects. The aforementioned river regulations and other anthropogenic measures throughout almost two centuries dramatically reduced river continuity and lateral connectivity with negative impacts on the distribution and abundance of species. Together with these effects, substantial pollution since the beginning of industrialization until the 1970s resulted in a collapse of biodiversity. Diversity has largely recovered since, due to improved water quality, however, faunal communities differ greatly from the historic original.
Today the River Rhine is by far the most important waterway in Europe and is subject to a wide range of uses. About 60 million people live in its catchment area. In addition to its role as a transport route, numerous sectors such as the water supply for households, industry and trade, irrigation for agricultural needs, wastewater disposal, energy generation, flood drainage and recreation each have their own specific demands on the Rhine.
Against this background, the Supersite Middle Rhine is a very well suited ‘living lab’ to conduct research on today’s challenges of a high-traffic, hugely modified and regulated waterway. BAW will contribute modelling and river engineering expertise, focusing on the support of sustainable solution development for sediment management, water sufficiency and eco-friendly river training structures, to improve ecosystem diversity and ensure the continuance of ecosystem services. Besides support on sustainable solution development, BfG will cover biological and chemical parameters as well as the measurement and analysis of parameters affecting water and sediment quality, including nutrients and (emerging) pollutants.
On this basis and participating in DANUBIUS-RI the vision is to develop strategies, which meet set goals like:
- Re-establish biological river continuity in all dimensions, improved habitat quality and quantity as well as higher habitat diversity
- Shift towards a more natural connectivity between river channel, cut-offs, abandoned river courses, oxbow lakes and floodplains without negatively affecting important uses
- Improved hydromorphologic conditions
- Balance of ecological functionality and value, socio-economy, a balanced portfolio of ecosystem services and satisfaction of societal needs along large and extensively used rivers.
These strategies shall be largely transferable to other large rivers in Europe and even worldwide.
