A few suggestions.

THIS refers to the recent spell of heavy rains in Karachi. The residents of Defence Housing Authority (DHA) braved similar rains in 2020 and expected better results this time. However, little has changed as far as water accumulation is concerned.

Though the DHA and the Cantonment Board Clifton (CBC) have done some repairs and arranged a number of generator-driven pumps near low-lying areas, the magnitude of rainwater remains beyond their capacity to handle.

I have some observations and suggestions for the DHA and CBC. There are many areas where sewerage is diverted into storm water drains. The design velocity of sewerage and storm water is different.

Storm water drains have huge cross-sectional areas, while a higher cross-sectional area slows down the velocity of sewerage, which results in the solids settling down in storm water drains. The soil and the sand blown into the storm water drains also settle at the bottom.

All this, in turn, drastically reduces the depth and capacity of the drains. The designed gravity flow alone fails to drain rainwater, and...