Heavy flooding in Niger over the past few weeks has killed up to 65 people and left 125,000 homeless.
The UN says the southern Dosso region is the worst affected, with 14,000 homes destroyed.
The capital Niamey was also hit when the River Niger burst its banks, flooding the city's suburbs.
Plan International Niger director Rheal Drisdalle said the river on 18-19 August reached levels not seen since the 1920s.
"As the river has not been this high for a very, very long time, people built their houses near the river and all the rice paddies along the river have been flooded," he told the BBC.
Niger already has severe food shortages caused by recent drought.
President Mahamadou Issou pledged 1400 tonnes of food and 900,000 euros in aid for people affected by the flooding, but said that would not be enough and called for international help.
The BBC reports 35 tonnes of supplies on a plane chartered by Ireland arrived on Sunday.
Sierra Leone, Burkina Faso and Ghana have also experienced higher than average rainfall and flooding this season.