Recent Floods in Pakistan
On September 2, 2021, life in Karachi was brought to a standstill by heavy rainfall and urban flooding. Before that, two people in Islamabad lost their lives to urban floods on July 28th. Urban floods, especially during the monsoon season have become somewhat of a regular phenomenon in Pakistan for several years now and the situation is getting worse by the day.
Getty Images/AFP/R. Tabassum
Causes of Urban Flooding in Pakistan
While discussing the causes of urban flooding, the most obvious that comes to mind is climate change. One can hear things like excessive rainfall with a high intensity almost immediately after the floods start unraveling the cities' infrastructure, often from those responsible for the administration of the cities hit by these floods. The issue to be discussed is whether climate change and change in rainfall patterns are the only things responsible for these floods or are there some deeper structural issues in our governance model that expose us to the deadly effect of urban floods year after year.
There is no denying the fact that climate change is responsible for at least a portion of the problem. However, by blaming only climate change for urban floods politicians from across the political spectrum try to find an easy way out and relieve themselves from the responsibility of solving the structural governance issues. These issues include institutional lethargy, lack of proper planning, and receding vegetation in the urban areas of Pakistan.
On the institutional front, municipal workers aren't fulfilling their duties, most of the stormwater drains are clogged due to lack of cleaning for months on end. There is no proper solid waste management system. Usually, some open space is used for dumping the solid waste of the whole city. This gives rise to an unhealthy and dangerous situation and contributes further to the worsening urban floods as it blocks the pathways for rainwater to flow out into flood plains outside the city.
Unplanned urban sprawl has resulted in the proliferation of ghetto communities and Katchi Abadis that are usually built on drainage pathways. The E11 flood in Islamabad in July 2021 was caused due to blockage of the drains by unauthorized construction. This situation increases the chances of flooding and enhances the risk to life and property as people live directly in the path of flood streams.
Big cities in Pakistan are increasingly transforming into concrete jungles. There are hardly any trees or green areas in the major urban centers of Pakistan. Concrete cannot absorb stormwater, the infiltration capacity of land becomes zero. Consequently, total rainfall converts into surface runoff that exceeds the capacity of the "non-functioning" storm drain in our cities. The runoff thus flows out into the streets and houses resulting in urban flooding.
How to Control Urban Flooding in Pakistan?
Urban floods can cause immense devastation to the life and property of the people. Thus, it is of paramount importance that measures are taken to control these floods. Floods can be controlled by developing Sponge cities, separating storm drains from the sewer lines, and creating more floodplains surrounding the city.
Sponge Cities
The idea of Sponge cities was proposed by Chinese researchers from Peking University in 2014. As the name suggests, sponge cities absorb and trap rainwater to be utilized for domestic and irrigation purposes. Stormwater can be trapped in underground tanks or through vegetation and can be used at the time of need for watering of trees in parks and on green belts of roads or for bathroom flush systems and maybe even for drinking after proper treatment. This system further helps in the recharging of the depleting groundwater aquifers. Work has been started on the implementation of this idea as the government of Punjab developed an underground storm tank in Lahore last year. However, a single underground tank cannot solve the problem of urban flooding. A lot more needs to be done before we can develop sponge cities.
Daisy Gill (Earth.org)
Separation of Storm Water Drains from Sewer Lines
Another method of controlling urban floods is by separating stormwater drains from the sewer lines to reduce pressure on the stormwater. Sewer lines carry the wastewater throughout the year and thus have a high chance of getting clogged by unfiltered solid waste from the sewage. In addition, separation of the two will reduce water load on the stormwater as well as the sewage is taken by a separate system.
Rohit Gujjar (Medium.com)
Development of Floodplains Outside the City
Cities need to be surrounded by low-lying floodplains where all the stormwater from the cities can be drained. Unplanned urban sprawl has resulted in the reduction of available floodplains for cities to drain their stormwater off to. Masterplans need to be developed for all the cities to accommodate people living in the ghetto communities on floodplains and streamlines and to free those spaces for floodwater drainage.
Yamuna Floodplain Delhi (times of India)