2019, Duisburg-Bearl & Tönisvorst), and a minimum of (February 1929, in Pfaffenhofen an der Ilm). Examples Land use of Germany Germany covers a total of , of which is irrigated land and is covered by water, the largest lakes being Lake Constance (total area of , with 62% of the shore being German; international borders are not defined on the lake itself), Müritz () and Chiemsee (). The majority of Germany is covered by either arable land (33.95%); permanent crops cover 0.57% of the land. Germany has a total of of coastline, and borders totaling (clockwise from north: Denmark , Poland , Czech Republic , Austria , Switzerland , France , Luxembourg , Belgium , Netherlands ). The German-Austrian border crosses itself near Jungholz. The border with Belgium includes 5 German exclaves because the Vennbahn railway is on Belgian territory crossing in and out of Germany. Rivers The main rivers in Germany are: The Rhine (Rhein in German) with a German section extending (main tributaries including the Neckar, the Main and the Moselle (Mosel)); The Elbe with a German section of (also drains into the North Sea); and The Danube (Donau) with a German length of . Further important rivers include the Saale and the Main in central Germany, the Neckar in the southwest, the Weser in the North and the Oder at the eastern border. Caves Throughout the Karst rocks many caves were formed especially in the valley of the Hönne. The biggest culture cave of Europe is located in Balve. Tidal Flats A recent global remote sensing analysis suggested that there were 2,783 km2 of tidal flats in Germany, making it the 11th ranked country in terms of how much tidal flat occurs there. Natural resources Iron ore, coal, potash, timber, lignite, uranium, copper, petroleum, natural gas, salt, nickel, and water. Environment Current issues Emissions from coal-burning utilities and industries contribute to air pollution; acid rain, resulting from sulphur dioxide emissions, is damaging forests in Germany; pollution in the Baltic Sea from raw sewage and industrial effluents from rivers in eastern Germany; hazardous waste disposal; government (under Chancellor Schröder, SPD) announced intent to end the use of nuclear power for producing electricity; government working to meet EU commitment to identify nature preservation areas in line with the EU's Flora, Fauna, and Habitat directive. Germany's last glacier is disappearing. International agreements Party to: Air Pollution, Air Pollution-Nitrogen oxides, Air