Urban flooding

06 Aug 2020


The writer is chairman, Department of Architecture & Planning, NED University, Karachi.
The writer is chairman, Department of Architecture & Planning, NED University, Karachi.

SOME days after Karachi braved a bout of devastating urban flooding in late July, the federal government swung into action. Prime Minister Imran Khan directed the chief of the National Disaster Management Authority (NDMA) to begin action with military assistance.

Unfortunately, the provincial government has continued as before. Even the Karachi Metropolitan Corporation has not changed course. The mayor continues to lament the unavailability of funds, the provincial government’s non-cooperation and his limited powers. A blame game has begun between the leadership of the three tiers of government. As Karachi is likely to receive more torrential downpours this month, it is time for swift action, and not a war of words.

None of the causes of flooding should be ignored. Real estate development — including in areas which city plans had recommended for rearing livestock, urban agriculture, forestation etc — has severely altered the topography of the natural terrain. The Karachi Development Plan, 1973-85, with its series of meticulously developed maps, shows the reality of this.

The July rain episode was less in terms of intensity, duration and measurement when compared to earlier downpours in the city. But the many evictions and ‘anti-encroachment drives’ proved ineffective in enabling the water to drain effectively.

Karachi should prepare for the next torrential downpour.

British grid-based development had established civil quarters and cantonments. Visible distance was kept between the native city close to Lyari and the new settlements following a rectilinear pattern. The British enforced a municipal system to plan and develop the urban infrastructure, responding to emerging needs. Storm-water drains were an essential ingredient of this approach. Land surveying, estimation of precipitation and implementing the findings of topographical studies enabled rainwater drainage and ensured Karachi could withstand torrential rains.

The sewerage system was planned in sync with the drainage system though both functioned independently. Periodic maintenance, repairs and proper monitoring ensured reliable performance. Manuals, SOPs, estimations and projections were diligently prepared so that the staff could function efficiently. Science, engineering wisdom and urban planning enabled the Raj administration to manage Karachi well. The system deteriorated when these practices could not be institutionalised after independence.

Rapid experimentation and changeovers in local government systems left Karachi without a management structure and democratic decision-making process. Unplanned land conversions for commercial gains, the rise of informal settlements, many situated dangerously on the edge of nullahs, and the gradual replacement of proper planning with isolated projects played havoc with the urban infrastructure, including storm-water drains.

Until three decades ago, Karachi’s system of storm-water drains, natural and manmade, used to mitigate flooding. But encroachments and other developments have hindered the proper drainage of rainwater. The hydrology of drains is also impacted by illegal sand mining that continues relentlessly along natural water courses. Many formal outfits have also encroached upon these nullahs, hindering the free flow of water. The parking lot of a major judicial office is apparently constructed over a drain. Unrestricted dumping of solid waste directly into the nullahs also restricts the flow of water. Poor road repair raises the level of main roads, allowing rainwater to gush into lanes and streets.

A thriving informal sector uses waterways as sites of waste-recycling enterprises. With the connivance of municipal staff, much of the waste is brought to nullah sites where recyclable items are separated and organic or worthless waste allowed to settle in riverbeds. Thus, silt content continues to expand. Lasbela area, along the Lyari river, houses an informal enterprise linked to recycling. When Karachi faced torrential rains some 10 years ago, locations along the river and nullah edges were severely flooded as the water could not find an appropriate path for outward flow.

With more predictions of heavy rain, the local and provincial government — with NDMA’s assistance — must identify unsafe locations all across the city. People should be asked to take precautionary measures. Deployment of government personnel to assist them in safeguarding life and property must be ensured.

The authorities should no longer waste time: roadside drainage channels must be cleaned immediately, solid waste removed from water bodies, riverbeds dredged, and embankments strengthened. Equally important is rehabilitating urban sewerage schemes and separating them from drainage schemes, as well as procuring cost-effective hardware for desilting water channels and creating voluntary resettlement options for those dwelling near nullahs. The natural absorption of water through appropriate strategies must be expedited.

The writer is chairman, Department of Architecture & Planning, NED University, Karachi.

Published in Dawn, August 6th, 2020