It’ll flood again
“Water, water everywhere Nor any drop to drink” — Samuel Taylor Coleridge
THE National Disaster Management Authority, the Sindh government, and Karachi’s local government institutions have widened the nullahs of the city and built embankments along some of them to prevent buildings from being constructed within the nullahs and to prevent soil erosion within them.
In the process, they have removed 15,000 houses that were considered ‘encroachments’, and which were supposedly preventing the flow of water through the nullahs. As a result, numerous families have become homeless and destitute, and that too in a poor country which already has huge housing shortages.
All this was done so that Karachi should not flood again. Meanwhile, some of the embankments have already collapsed, defeating the purpose for which they were built.
People like me have consistently predicted that none of this alone would stop Karachi from flooding again and that some recent road work would increase its propensity to flood. It has now rained again — but not heavily. Yet the roads have been turned into raging rivers, and low-lying areas along the newly constructed roads have become lakes with no disposal points. Water from some of these low-lying areas cannot drain into the sea. There are huge traffic jams, and Karachiites spend hours waiting in cars and rickshaws for traffic to ease. Motorcyclists and individuals have to wade through the water to reach their destination. More often than not, this water is mixed with the rising level of sewage in the sewer trunks.
The reasons for this continued flooding are simple. The roofs and compounds of all Karachi residential and commercial buildings and of real estate colonies discharge their rainwater onto the roads on which they are located. From there, the rainwater finds its way along the roads to the nearest disposal points, which is usually a nullah or a depression.
Karachi’s roads have been turned into rivers.
In many Karachi settlements and commercial areas, the roads have now become higher than the compounds of buildings, and so the water flows off them into the settlements, which, in many cases, have no exit points for it. Some roads that the government has constructed recently are also higher than the areas they pass through, leading to flooding.
In their journey from the Kirthar foothills to the sea, the floodwaters encounter various obstacles in the shape of built-over torrents, high roads without sufficient culverts in them for the passage of water (such as the Northern Bypass), debris, and piles of solid waste.
Also, some sections of Karachi are so low that the water cannot drain out into the sea, and at high tide there is often a backwash from the sea, as in the case of certain sections of Defence Housing Authority (DHA), Lyari and Keamari.
In addition, the outfalls to the sea are also encroached upon, but government agencies have done nothing substantial to remove the encroachments so that floodwaters can enter the ocean without encountering obstacles. Maybe, this is because many of the outfall encroachments have been created by elite developments. The Nehr-i-Khayyam in Clifton and the Soldier Bazaar and City Railway Station drains have had their outfalls considerably constricted because of the reclamation of land from the Chinna Creek backwaters for the construction of the KPT Officers Housing Society.
Meanwhile, the Mehmoodabad nullah estuary, which was part of the Gizri Creek, has also been reduced from over a kilometre wide to less than 18 metres by the residential and commercial developments of DHA Phase 7. As a result, water from the 34 settlements that drain into the Mehmoodabad nullah are not only prevented from falling into the sea but receive a backwash from it at high tide.
From what has been discussed here, Karachi requires several collection points for low-lying areas from where water can be pumped into the sea. Alternatively, deep sea conduits can be constructed to dispose of water 10-12km away from the low-water mark. This process has been extensively used for disposal of waste water in many countries.
To take care of the flooding of roads, it is necessary to build storm-water drains on either side of them. At present, storm water uses the sewerage system for drainage (where it exists). This is insufficient to take the water of even moderately heavy rainfall. Each section of the storm-water drains should terminate at the nearest disposal point such as a nullah or depression that can be turned into lakes for recreational purposes. This can take place over time so as not to disrupt the functioning of the city. In addition, new road construction should not be higher than the level of the adjacent settlements.
These steps by themselves will not solve the problem entirely, but will lay the foundations for improving conditions substantially. Ultimately, it’s a matter of effective functioning of institutions of monitoring and management.
Published in Dawn, By Arif Hasan July 9th, 2022