The Danube, with a length of c. 2850 km, is the second largest river inEurope. It rises in the Black Forest (Germany), discharges into the BlackSea (Romania, former USSR) and crosses five other countries: Austria,Czechoslovakia, Hungary, former Yugoslavia, and Bulgaria (Fig. 1). Nearly90 million people live in its catchment area of c. 805 300 km². Includingits tributaries, twelve countries and about 447 million people are linked tothe Danube. These figures show the extraordinary internationalimportance of this river
