BERLIN—The German government agreed Tuesday to provide 30 billion euros ($35 billion) to help rebuild regions hit by devastating floods last month. Chancellor Angela Merkel and the heads of Germany’s 16 states approved the state flood aid package, which still needs parliament’s endorsement. “This is significantly more than we had for previous floods,” Merkel told reporters in Berlin. More than 180 people died in Germany and hundreds more were injured in the July 14–15 floods, which also claimed lives in neighboring Belgium. Heavy rainfall turned small streams into raging torrents, sweeping away houses, bridges, and cars. The cost of the German aid package—agreed just weeks before the country’s national election on Sept. 26—will be shared more or less evenly by the federal government and states, with the latter’s payments spread over 30 years. The two sides also agreed to establish a nationwide siren network and introduce a system that will …