Danube

Europe’s largest transboundary watercourse, the Danube, covers a catchment area of 817,000 sq km. Its headwaters lie in Germany. Other riparians, all countries contributing to the runoff of the catchment on its way to the Black Sea, include Austria, Slovakia, Hungary, Croatia, Serbia, Romania, Bulgaria, Moldova, Ukraine, Switzerland, Czech Republic, Italy, Slovenia, BosniaHerzegovina, Macedonia and Albania. It has been a major navigation watercourse since ancient times and is approximately five times larger in size and discharge than the Rhine, another European basin. Since 1992, these two basins have been interlinked for navigational purposes through the RhineMain-Danube channel, connecting the two main European waterways and their ports between Rotterdam in the Netherlands and the Black Sea. Early human interventions in the natural flow regime of the Danube date

back to the 15th century, when dikes were constructed to control floods. Over the centuries, objectives and infrastructural measures evolved and resulted in control weirs, drainage channels and pumping stations until the 19th century. With the advent of hydropower plants and dredging activities to meet the interests of the Habsburg empire ruling in the middle and lower reaches of the basin, the hydrologic flow regime of the stream changed drastically. Causes for this are the trapping of sediments in reservoirs, and the deepening of the river bed and its lining; the effects were more frequent flood events in what today are the Danube plains of Slovakia and Hungary. The infrastructural activities designed to enable navigation and hydropower generation resulted in considerable decline of the Danube aquifer, Europe’s largest natural freshwater reservoir underlying an area between the Slovak capital of Bratislava and Nagymaros in Hungary, and led to degradation of adjoining freshwater ecosystems. However, environmental and economic concerns also gave birth to plans dating back to the 1950s, when, under the Warsaw Pact, plans were proposed mutually to develop hydropower infrastructure. The approval of such a plan in the 1960s was accompanied by increased concerns about the environmental impact of power generation by fossil sources of energy in the socialist republics of Czechoslovakia and Hungary. An agreement on the specifics, objectives and the sharing of costs of the project, the GabcikovoNagymaros project (GNP), was signed in 1977, stating joint financing, investment and benefit-sharing and its single and indivisible character as the pillars of co-operation. However, political and economic challenges during the 1980s and early 1990s significantly altered formerly envisaged outcomes.