DAR ES SALAAM, Sept. 25 -- WHEN dark clouds gather over Dar es Salaam, residents in low-lying neighbourhoods do not only watch the sky; they watch the drains, rivers and roads, knowing that a few hours of heavy rain can quickly turn familiar routes into waterways.

For a city whose population and built-up areas have expanded rapidly, flooding has become more than a seasonal inconvenience. It raises a fundamental question: When rain falls on Dar es Salaam, where does the water go?

The question is becoming more urgent as the Tanzania Meteorological Authority (TMA) forecasts a strong El Niño influence during the October, December 2026 rainfall season, with above-normal to normal rainfall expected in many parts of the Northern Coast, in...