Pakistan: Lahore’s flooding is not just an infrastructure problem, it’s a climate change issue
By Dawar Nauman, policy analyst and communications consultant
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In the 17 hour-long rain spell on July 16, Lahore’s famous Lakshmi Chowk received more than 250mm of rainfall. To put things into perspective, the average rainfall for the whole month of July (mean from 1961-1990) was 202mm. In 1996, the city received 496mm of rain in 36 hours during a monsoon rain spell, breaking all records in recent memory. The Ravi – which at the time was not hindered on the Indian side – overflowed and most of the city flooded. It was an anomaly, which has not been repeated, because the water flows massively declined in the last two decades. But Ravi does not need overflow to have Lahore flooded. A combination of above-average rainfall and ‘over-development’ has made Lahore regularly witness pluvial flooding, for which no cure or mitigation seems to have been developed.
As Lahore’s urban sprawl kept growing, the city-managers have largely failed to cater to its drainage needs. This simply means that while housing societies, concrete boulevards, flyovers, underpasses, high-rises and signal-free corridors have popped up all over the city, green spaces and the urban tree canopy has had to bear the brunt of these developments. At the same time, the capacity of Lahore’s drainage system has been declining.
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The eight main drains had always been vulnerable to siltation. Surface runoff deposited large amounts of sediment into these drains. A Japan International Cooperation Agency project study in 2004 revealed that nearly 400,000 cubic meters of sediment deposits had gathered in these drains, which were gradually removed by assistance from the Japanese Aid Agency to the Water and Sanitation Authority (WASA). The sediment deposits, in effect, reduce the carrying capacity of the drains, making them less and less effective in times of heavy rainfall. With reductions in green-cover and water absorption into the soil, and increased surface run-off of sediment into the drains, Lahore can no longer deal with the yearly episodes of monsoon rainfall.
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