Such maps exist (called "Hochwassergefahrenkarte" in Germany), but comparing the picture of Altenburg linked elsewhere in this topic and the map, the flooding h

Such maps exist (called "Hochwassergefahrenkarte" in Germany), but comparing the picture of Altenburg linked elsewhere in this topic and the map, the flooding has significantly exceeded even the "HQ extrem" (= extreme flooding, defined as a 200-year-or-rarer flood) level. And officially designated flood plains with associated legal restrictions are usually based on a 100-year flood.