WASSENBURG, Germany/BRUSSELS—Rescue workers searched flood-ravaged parts of Germany and Belgium for survivors on Saturday after burst rivers and flash floods this week collapsed houses and claimed at least 157 lives. Some 133 people have died in the flooding in western Germany, in the country’s worst natural disaster in more than half a century. That included about 90 in the Ahrweiler district south of Cologne, according to police. Hundreds of people are still missing. Around 700 residents were evacuated late on Friday after a dam broke in the town of Wassenberg near Cologne, authorities said. “Water levels have been stabilizing since last night, one can say the situation is stable,” Wassenberg mayor Marcel Maurer said. “It’s too early to give the all-clear but we are cautiously optimistic.” In Belgium, the death toll rose to 24, according to the national crisis center, which is coordinating the rescue effort. “Unfortunately, we have to …