Faduwar ruwan Blue Nile ruwa ne dake kan kogin Blue Nile a Habasha. An san shi da Tis Abay a cikin Amharic, ma'ana "babban hayaƙi". Ya kasance a saman kwarin kogin, kimanin kilomita 30 (19 mi) zuwa ƙasa daga garin Bahir Dar da Lake. Faduwar ruwa na daya daga cikin sanannun wuraren shakatawa na Habasha. Ruwayen suna da mita 42 (kafa 138), wanda ya kunshi rafuka huɗu waɗanda asalinsu ya bambanta daga abin gudu a lokacin rani zuwa fiye da mita 400 faɗi a lokacin damina. Dokar Tafkin Tana yanzu ta rage bambancin kadan, kuma tun daga 2003 tashar ruwa mai amfani da lantarki ta kwashe yawancin kwararar daga faduwar sai dai lokacin damina. Faduwar ruwan Blue Nile ya keɓe yanayin halittar Tafkin Tana daga na sauran halittun na Kogin Nilu, kuma wannan keɓewar ya taka rawa wajen ci gaban dabbobin da ke cikin teku. Shortan nesa kaɗan daga faɗuwa ya zauna gadar dutse ta farko da aka gina a Habasha, wanda aka gina bisa umarnin Emperor Susenyos a 1626.