The wadis in the Tibesti are called enneris. The water originates from the storms that periodically rage over the mountains. Their flow is highly variable. For example, the largest wadi, named Bardagué (or Enneri Zoumeri on its upstream portion) and located in the northern part of the range, recorded a flow of in 1954, yet over the next nine years it experienced four years of total drought, four years of flow less than and one year where three different flow rates were measured: . This variability is partly due to the irregularity of the monsoon that can bring rainfall from the southwest up to 20 degrees north latitude, but in some years may retreat before it reaches this latitude. Two other significant rivers cut into the mountains: the Enneri Yebige flows northward until its riverbed disappears on the Sarir Tibesti plateau, while Enneri Touaoul joins the south-flowing Enneri Ke to form Enneri Miski, which then disappears in the plains of Borkou. Their basins are separated by an high watershed that runs from Tarso Tieroko in the west to Tarso Mohi in the east. The Enneri Tijitinga is the longest wadi in the range, flowing some southward. It forms in the west of the range and peters out in the Bodélé Depression, as does Enneri Miski a little further to the east, along with other wadis such as the Enneri Korom and Enneri Aouei. The Enneri Douanré also flows southward. The Enneri Torku and Enneri Ofoundoui lie to the north; the Enneri Uri, Enneri Binem and Enneri Modiounga are in the east; the Enneri Yeo, Enneri Mamar, Enneri Tao, Enneri Woudoui and Enneri Dooze are to the west. Several rivers flow radially on the southern slopes of the Emi Koussi before seeping into the sands of Borkou and then reemerging at escarpments up to south of the summit, near the Ennedi Plateau.