A senior official in South Omo region said 1,800 people had been moved to safety so far since hundreds of families were surrounded when the Wotio River burst its banks last week.
"The flood covered Erbor locality, which is flat, and formed a lake encircling the inhabitants," deputy administrator Negatu Dansa told Reuters by telephone. No one had died, he said.
Local disaster relief officials were providing the displaced with food and shelter, he said. Some 48,000 Ethiopians were uprooted by flooding last year, according to U.N. estimates.
Floods typically hit lowland areas after heavy rains between June and September drench the country's highlands.
©Reuters