In the report published on Wednesday, no exact figures were given for the number of those killed or injured.
However, preliminary data indicate that up to 7,500 homes have been damaged or destroyed.
OCHA warned that protection risks in flood-affected areas have risen sharply; more than 14,000 people are at risk of gender-based violence. In addition, the movement of unexploded ordnance and mines by floodwaters is threatening the lives of around 2.7 million people in contaminated areas.
The agency added that from 17 April to 26 April this year, large areas of agricultural land were destroyed by flooding, putting the livelihoods of thousands of rural families at risk.
The report said the floods have deepened humanitarian needs and increased the risk of food insecurity, the spread of diseases and homelessness.
According to OCHA, immediate priorities include emergency shelter, safe water, healthcare services and food assistance.
The agency said humanitarian partners are responding, with the delivery of rescue equipment and services, temporary shelter, and water and sanitation support under way.
At the same time, assessment teams have been deployed to various provinces to provide more accurate estimates of casualties, damage and needs, so that continued aid can be planned based on field data.
OCHA said that urgent needs for 56,900 people have so far been confirmed; aid teams have reached around 31,000 people with emergency assistance, including food, cash, temporary shelter and health services. Assessments in 34 districts are still ongoing, and the number of people in need is expected to rise.
Critics and experts say the Taliban’s excessive focus on social restrictions has sidelined crisis management and the rebuilding of deteriorating infrastructure.
While seasonal floods have long threatened lives and livelihoods, Taliban authorities have, instead of investing in infrastructure, allocated a large share of Afghanistan’s resources to their security and propaganda apparatus. Critics say the lack of disaster preparedness is now imposing heavy costs on the poorest segments of society, who have been left stranded in floodwaters and mud.
Meanwhile, restrictions imposed by the Taliban on women’s participation in aid organisations have reportedly affected the effectiveness of assessment teams in disaster-hit areas.