Ambaliyar kogin Nilu ya kasance muhimmin zagayowar yanayi a ƙasarMasar tun a zamanin da . Masarawa suna bikin ne a matsayin hutu na shekara-shekara na makonni biyu daga kimanin 15 ga Agusta, wanda aka fi sani da Wafaa El-Nil . Hakanan ana yin bikin a cikin Cocin 'yan Koftik ta hanyar biki ta jefar da shahidi a cikin kogin, don haka sunan, Shahidai ( Coptic ⲡⲓⲧⲏⲃ , Larabci: Esba` al-shahīd‎ ). Masarawa na dā sun gaskata cewa kogin Nilu yana ambaliya kowace shekara domin Isis ya yi hawaye na baƙin ciki ga mijinta da ya mutu, Osiris. Ambaliyar kogin Nilu sakamakon damina ne na shekara tsakanin watan Mayu da Agusta wanda ya haifar da hazo mai yawa a kan tsaunukan Habasha wanda kolinsu ya kai tsayin mita kusan 4550 (14,928). ft). Mafi yawan wannan ruwan sama da kogin Nilu ne da kuma kogin Atbarah ya shiga cikin kogin Nilu, yayin da wani abin da ba shi da muhimmanci ya ratsa ta cikin kogin Sobat da farin Nilu zuwa cikin kogin Nilu.