Danube-Auen National Park on both land and water, and other invertebrates, the total number of species in Donau-Auen National Park is estimated to be at least 5,000. Danube-Auen National Park Donau-Auen National Park () covers 93 square kilometres in Vienna and Lower Austria and is one of the largest remaining floodplains of the Danube in Middle Europe. The German word Aue (variant Au) means "river island, wetland, floodplain, riparian woodland", i.e. a cultivated landscape in a riparian zone. The words Aue and Au occur in a large number of German place names—including Donau, the German word for the Danube River—and refer to forests,
Danube–Tisa–Danube Canal 1895 and 1899. István Türr participated in the compilation and implementation of the plans. The dam locks are powered by electricity. The electrical power required for operation is provided by the lock-built hydroelectric power generator. According to the official records, delegations arrived from as far as Japan for the inauguration ceremony. At the time of its construction, it was one of the most sophisticated dam-locks in the world. Danube–Tisa–Danube Canal Danube–Tisa–Danube Canal (DTD) () is a canal system in Serbia. It is a unique hydro-engineering system for flood control and hydrotechnical management, amelioration, forestry, water supply, waste water evacuation, navigation,