Sunrise on the Omo River. The Omo River rises in the Ethiopian Highlands and flows for over 600 miles before discharging its waters through a delta into the northern end of Lake Turkana. It is one of the largest inland deltas in the world. Once a year following rains in the highlands, the river rises and bursts its banks, flooding the low-lying plains. After the water has subsided, the people living along its banks plant crops in the fertile soil.