Tundzha River References Tundzha River river, Bulgaria Ask Anything Homework Help Written by The Information Architects of Encyclopaedia Britannica The Information Architects maintain a master list of the topics included in the corpus of Encyclopædia Britannica, and create and manage the relationships between them. The Information Architects of Encyclopaedia Britannica Britannica AI Ask Anything Learn about this topic in these articles: Bulgaria/ DrainageArda, Tundzha, and Yantra. Overall, more than half of the runoff drains to the Black Sea, and the rest flows to the Aegean Sea. Read MoreArda, Tundzha, and Yantra. Overall, more than half of the runoff drains to the Black Sea, and the rest flows to the Aegean Sea. Read More