When our cities flood

Published August 10, 2015
The writer is professor and chairman, department of architecture and planning, NED University Karachi.
The writer is professor and chairman, department of architecture and planning, NED University Karachi.

CITIES in Pakistan have braved devastating monsoon rains during the previous month. Urban flooding has paralysed many towns, cities, peripheral settlements and neighbourhoods, especially in the north of the country.

Low-lying housing clusters were swiftly inundated with hapless residents struggling to save themselves and their basic household articles from washing away. Nullah Budhni, a major waterway in Peshawar, overflowed causing the adjoining residents to run for life. Rawalpindi’s dwellers also experienced heavy rains that made the water level in Nullah Lai rise to a dangerous extent. Lahore faced torrential rains as well that virtually submerged low-lying areas.

While Karachi received drizzle and less intense showers, the situation may have become serious in the wake of any heavy downpour.

Inadvertent developments and encroachments — some even in the river or nullah beds — hinder the smooth removal of rainwater.

Rains and consequent urban flooding is a recurring phenomenon. The meteorological department had warned that under the climate change regime endured locally and globally, the frequency of heavy but erratic rains shall increase. Little preparation was done to brace for this calamity that caused a number of casualties as well as losses to private and public assets.

A cursory review of our urban contexts is vital to understand flooding and related issues. Most of our cities have evolved and built upon the historic footprint. A walled city with traditional organic morphology, British-led grid-based organised new city with civil quarters and cantonments, and postcolonial additions of very large scale constitute the common denominators of medium- and large-sized cities. The British enforced a municipal system to plan and develop urban infrastructure, swiftly responding to emerging needs. Storm-water drains were an essential ingredient of this approach.

Utilising the available methods of land surveying, estimation of precipitation, topographical studies and assessment of surrounding terrain/catchments, the cities were reinforced for effective rainwater drainage and made capable to withstand torrential rains also. The sewerage system was planned in consonance with drainage, though the two components functioned independently. Periodic maintenance, cyclic repairs and an effective monitoring process made the system and its performance dependable.

Manuals, standards, operating procedures, estimations and projections were diligently prepared to make the staff function efficiently. Scientific utilisation of engineering wisdom and urban planning logic enabled the Raj administration to manage our cities well. The same work was continued after independence by the cadres trained during the Raj. The systems became warped when these practices could not be institutionalised.

Rapid experimentation and changeovers in local government systems left cities without a management structure and democratic decision-making process. Unplanned land conversion for commercial gains, rise of informal settlements due to absence of low-cost housing options and gradual replacement of rational planning with isolated projects played havoc with the urban infrastructure, including storm drains.

Most of the urban settlements are located along the banks of the Indus, its tributaries, lakes, smaller river systems, canals and other water bodies. Till perhaps three decades ago, a system of storm drains, natural and man-made, used to mitigate flooding. But inadvertent developments and encroachments — some even in the river or nullah beds — hinder the smooth removal of rainwater. The banks of Nullah Budhni in Peshawar, Nullah Lai in Rawalpindi, Nullah Bhed in Sialkot, Phuleli Canal in Hyderabad and more than 13 major nullahs, as well as the Malir and Lyari rivers in Karachi, are cases in point.

The hydrology of drains is also impacted by illegal sand mining that continues relentlessly along natural watercourses. A recent report by Arif Hasan, the well-known architect and researcher, reveals that about 60 billion cubic feet of sand and gravel has been removed during the past few years from the Gadap/Malir riverbed alone. Unrestricted dumping of solid waste directly into the nullahs or channels impedes the flow of water and reduces the carrying capacity. Almost all cities in the country are without a practical and sustainable solid waste management system.

A thriving informal sector uses nullahs and urban rivers as sites of waste recycling enterprises. With the connivance of municipal staff, much of this waste is regularly brought to the nullah sites where recyclable items are separated and organic or worthless waste is made to settle in riverbeds. Thus the content of silt continues to expand. The Lasbela area in Karachi along the Lyari river houses an informal location linked to recycling. When Karachi faced the torrential rains of 2009 and 2010, locations along river and nullahs were severely flooded as the water could not find an appropriate path for outward flow.

Unpredictable weather patterns are now to be expected. Cities and fringe settlements need physical reconfiguring with respect to urban drainage and land-use management. Mandatory construction and cleaning of roadside drainage channels, ensuring gravity-based adjustments of existing drains and nullahs (to allow water to automatically discharge), preventing solid waste dumping into drains/water bodies, consolidating embankments and dredging beds of urban rivers/nullahs, rehabilitating urban sewerage schemes and separating them from drainage, the procurement of cost-effective hardware for de-silting, creating voluntary resettlement options for nullah dwellers and accelerating natural absorption or recharge of water through appropriate floodwater retention strategies are some vital prerequisites.

These tasks correspond to municipal functions. Thus provincial governments will do well to pass on this responsibility to municipalities and help build their capacities.

The writer is professor and chairman, department of architecture and planning, NED University Karachi.

Published in Dawn, August 10th, 2015

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