Karachi, the capital of Sindh province, is the economic hub of Pakistan with a population of over 20 million people. It requires special attention. Though it has many problems, I will discuss only stormwater drainage, non-existence or inefficiency of which creates havoc, resulting in damaged roads, disruption of traffic, etc.
Being a civil engineer with diversified experience involved in drainage projects design and construction and having worked on senior positions in Pakistan and Australia, including Karachi, I am of the view that the available resources should be utilised to cater to increased population requirements by utilising rainwater while considering environmental protection.
Karachi enjoys the presence of two natural drainage outlets; Lyari and Malir rivers, which can be utilised efficiently. Hydraulics estimate water discharge conduit, by area, width and depth, and velocity which determines how much water can flow. By increasing both, water can be drained out efficiently without allowing it to accumulate anywhere.
Area can be increased by digging deeper as more width is not possible in cities. Velocity of water can be increased by converting riverbeds into half-pipes, like the London underground drainage system, with grooves on concrete floor, to create whirling force, which throws forward water to the location of storage or diversion.
The two rivers in Karachi are many kilometres long — Lyari 50km, and Malir 20km — and, therefore, many reservoirs can be built at appropriate locations, by excavation, say 100 meters deep and 5km-long, where water can be stored and from there it can be pumped out for parks, car-cleaning or can even be used after due treatment for milk-producing animals.
From the environmental point of view, some water must go into the sea. But these rivers are being used as sewerage outlets and will continue that way. Therefore, before letting water go into the sea, it
has to be treated professionally. This way we can utilise the rivers in increased capacity to drain water, utilise most rainwater, as well save sea environment.
SHAFIQ MUSAVI
AUSTRALIA
