Bangladesh, July 16 -- Heavy rain has once again exposed the fragile drainage systems of Dhaka and Chattogram, leaving large parts of Bangladesh's two biggest cities under water.

Experts say the flooding was not caused by rain alone. They blame a chain of man-made failures. Among them are poor waste management, filled-up water bodies, blocked canals, unplanned sluice gates, disconnected drains, and the loss of natural channels that once carried rainwater into rivers.

In both cities, water that should have flowed into rivers and canals either could not move fast enough or flowed back into the streets.

Waist-deep water accumulated on Arambagh Road after continuous rain in Dhaka. Waist-deep water accumulated on Arambagh Road after conti...