Around 3000 families of about 50 villages under eight unions of the upazila were marooned in flood waters.
The floods also damaged fields of Aman paddy seeds, roads, ponds, trees and houses.
Kalmakanda Upazila Agriculture official Md Faruk Ahmed said 55mm rain was recorded till Sunday morning in the upazila.
Around 14 acre fields of Aman paddy seeds have been inundated, the official added.
Upazila Nirbahi Officer Md Sohel Rana and the upazila chairman Abdul Khalek Talukder visited the flood-hit areas.
They said cash money and rice are being distributed among the flood-hit people and the upazila administration has all kind of preparation to overcome the disaster.