koblenz, germany - 09 06 2021: muddy rhine side arm at niederwerth

river cloud landscape sky tree reflection horizon hill reservoir plain wetland waterway lake skyline coast marsh sea koblenz germany 2021: view niederwerth island bridge city rhine mosel small marks north unesco world heritage mittelrheintal deutsches eck estuary 2000 years history name confluentes roman times writing coblenz centuries muddy side arm