Urban Flooding

Tackling the challenge of drowning cities

M. Atif Sheikh

It’s morning time and there is a lot of hustle and bustle in the house; kids have to go to school and men to work, but the street outside is looking like a canal due to the heavy rain last night. Suddenly, a mobile phone bell rings; the person on the other side tells that the rainwater has entered your shop and warehouse. Upon hearing this, the head of the family gets worried. His condition deteriorates and he needs immediate treatment. But, reaching a hospital seems impossible as street is flooded with rainwater and not even a motorbike can be waded through, let alone a car.

There has been no electricity for the past two days due to heavy rain. The owner of a famous restaurant seems distressed as no customers could come to the restaurant due to inundated roads; even home delivery is not possible. In such a situation, how the edibles can be stored in freezers as the generator has run out of fuel and re-fuelling is not possible due to blocked roads.

There is ‘operation day’ in a famous hospital in the city. But, most surgeons and the auxiliary staff could not reach the hospital as the roads are clogged due to excessive rainwater.

A daily wager has to reach his workplace but there is no transport on the road due to urban flooding. He seems perplexed how he would arrange bread for his kids. Moreover, if he doesn’t reach the workplace, his salary will be deducted.

Rain-caused electricity outages have interrupted the supply of drinking water to the city. Furthermore, due to outdated and dilapidated supply lines, rain- and sewerage water is getting mixed with the clean water.

Although the rain has stopped, but the stagnant water hasn’t been drained out yet due to which mosquitoes and other vectors of various diseases are now in abundance. Kids are catching ailments. Rainwater has been drained out yet mud and odour have inflicted misery to common people. Mud has dried and there is dust all around that has made breathing difficult.

These are some examples of the crises caused by urban flooding—a situation where the inundation of property is caused by rainfall on increased amounts of impervious surfaces and overwhelming the capacity of drainage systems. Whether it falls from the sky or springs from land, water makes its way. We find this natural phenomenon of water flow in the form of rivers, streams and other waterways. Moreover, humans can channel water to suit their needs with an apt use of technology and system. Even these systems are established keeping in view the natural flow of water. A glaring example of it is canals in rural areas and sewerage system in urban ones.

And, when both these systems get filled to their capacity, or their natural flow gets disrupted, the excess water flows out and starts running downslope. Experts call this phenomenon “urban flooding.” Such floods can hit both rural and urban areas and the major difference between the two types is that the flood in rural areas inundates vast swathes of land and affects mostly the poor people while the urban flooding results mainly due to poor drainage infrastructure because shrinking open spaces hamper the capacity of the soil to absorb water. So, when it pours down, the rainwater either submerges roads or enters the sewerage system. Heavy or torrential rains are the biggest cause of urban flooding. When the sewerage system is overfilled and is rendered unable to drain the rainwater out, it gets choked. In other words, it can be said that the urban flooding results when landscape of the city cannot absorb or otherwise manage rainfall.

A big example of this phenomenon is the city of Quetta. Karez once flowed around this beautiful city. The water from rainfall in Quetta and the surrounding hills flowed into these Karez, thus, keeping the city’s water table intact. But, later, when Quetta started expanding and its inhabited areas reached the hills in the suburbs of the city, the land inside and in the suburbs of the city—found mainly in the form of Karez, gardens, fields and empty spaces—which once regulated the absorption and flow of water beneath the soil, got covered with built infrastructure, e.g. concrete houses, buildings, commercial plazas and roads. Resultantly, today, even a little rainfall causes inundation of roads and the city looks like an overflowed stream. Since the sewerage system in Quetta consists of open sewers that were made for a limited population, in case of a heavy rain, these sewers overflow, resulting in urban flooding. Hence, the water which once recharged the city’s water table gets wasted.

Experts split the definition of urban flooding into three separate components: it is (1) caused by rain that (2) falls on impervious surfaces and (3) overwhelms local stormwater drainage capacity. This distribution points to three different factors: (1) heavy precipitation which is expected to become more frequent due to climate change, (2) increased urbanization and growing population of cities, and (3) insufficient or outdated stormwater infrastructure. Urban flooding sits at the intersection of all three.

Now, let’s analyze these three factors separately in the context of Pakistan.

Climate change is a global trend and its effects are more profound on developing countries like Pakistan. Over-reliance on natural resources, limited technical capabilities and insufficient financial resources to cope with the climate change-induced changes render the country prone to multifarious dangers and threats. Pakistan makes a tiny contribution to total global greenhouse gas (GHG) emissions, but it is among the countries most vulnerable to climate change. According to the Global Climate Risk Index 2020, Pakistan is fifth on the list of countries most affected by extreme weather events between 1999 and 2018. This is also substantiated by the figures presented by Centre for Research on the Epidemiology of Disasters, as per which floods killed 7,301 people in Pakistan between 2001 and 2020, leaving 12,022 people injured, affecting 46,0545,90 people and rendering 18,155 homeless, besides causing a financial loss of more than US$ 18 billion. Experts believe that rising temperatures is one of the effects of climatic changes owing to which there is all likelihood that the frequency and intensity of rain will rise in the coming years. Devastating rains and frequent heat waves in Karachi bear testimony to this fact.

According to a research study by UK Government Office for Science, climate change is adding an impetus to migration from rural to urban areas and the trend is expected to continue in future as well. At present, cities are facing a dual threat; on one hand, they are facing the challenge of migration from rural to urban areas while climate change is also a looming danger for them, on the other. Coming threats will multiply current vulnerabilities because climate change and rapid urbanization will lead to more instances of urban flooding. Urbanization is a complex process as it involves political, environmental, demographic, economic and social factors.  In Pakistan’s context, when we view urbanization in the backdrop of environmental and socioeconomic factors, we find that climate change-induced depletion of water resources in most parts of the country is spurring this phenomenon. In addition, changing weather patterns and increasing intensity and longevity of seasons are having adverse impacts on agricultural produce as well.

The gap between expenses and incomes is also widening day by day due to which the provision of civic amenities has been affected. Employment opportunities and other such factors in rural and urban areas have left people with no option but to abandon agriculture as a profession and move to urban areas.

Although increase in urban population can be witnessed in all cities of the country, as many as 15 districts are, however, most affected from this pressure. Our urban population has increased by 32,548,000 people between 1998 and 2017 but almost 56% of that occurred in 15 districts including 6 Karachi districts and Lahore, Faisalabad, Rawalpindi, Gujranwala, Peshawar, Multan, Hyderabad, Islamabad and Quetta.

Rapid urbanization is causing an unbridled growth and sprawl of cities which points to the expansion of the built infrastructure that will cause urban flooding. Urban development leads to destruction of ecological cover and impedes the natural flow of water. For instance, cemented roofs, paved streets and roads hamper the earth’s capacity to absorb water due to which that water enters sewers and drains and when they are filled, water spills out. Hence, we find rainwater or floodwater inundating roads and streets. A research study suggests that 40% of water after rainfall on open spaces evaporates, 10% flows on the surface whereas 50% is absorbed by the earth to recharge the underground water table. On the other hand, in built areas, only 25% of such water evaporates, 30% gets absorbed by earth while 15% becomes part of the sewerage system; it means only 30% of water enters the natural drainage system. Hence, our drainage systems have to bear an additional 45% burden of wastewater. In case of more rains, this share also gets increased.

A recent study on effects of climate change of Norway’s urban drainage system has found that if there is an increase of 20% in the rainfall, the ratio of urban flooding increases by 365% while the number of vulnerable buildings increases by 120%. However, when we look at Pakistan, we find that during the period between fifth and sixth population and housing censuses, i.e. in 1998 and 2017, the number of houses in the country’s urban areas rose from 6.03 million to 12.19 million—an increase of 102%. At present, 58% of houses in urban areas are concentrated in 15 abovementioned districts only and the increase in those during the inter-census period was 78.71% while their population grew by 60.6%— growth in number of houses was more than that in population.

When urban population increases, available resources and basic infrastructure comes under pressure. To make up for the shortage of houses, lands on the peripheries of the cities are converted into housing schemes, leading also to construction of more built infrastructure, e.g. shopping plazas, shops, roads, schools, hospitals, marriage halls, worship places, petrol pumps, and so on. It means the soil gets more concrete cover. This also leads to higher prices of land which, ultimately, affects poop stratum of the society as they have no option but to build their abodes on illegally occupied land or areas that are prone to many hazards and risks. In many instances, such settlements have been made on natural waterways or drainage systems, effecting a decline in their drainage capacity. In this state of affairs, even a little rainfall sometimes becomes a colossal problem.

Although urban flooding is caused by some manmade factors, it represents the incapacity of our sewerage systems to drain water out in time. Our ineptness is manifested in sheer negligence in maintenance and repair as well as timely cleaning of an already dilapidated drainage infrastructure. An overwhelming part of this system is still in the form of open and closed sewers and ducts which usually overflow even if there is little rain.

Public also have limited access to drainage and waste management systems. Pakistan Social and Living Measurement Survey 2018-19 reports that 35% of households in Pakistan have no drainage facility, 22% are attached to  underground sewerage system whereas 37% release wastewater in open and 5% in open sewers. In urban areas, 8% households have absolutely no sewerage facility, 50% release sewerage water in underground ducts, 32% in open sewers and 10 in closed ones. Owing to growing urban population, these systems have been overwhelmed. Our broken solid waste management system further adds insult to injury as 75% of houses in Pakistan have no access to such a system; this ratio is 41% in urban areas. Only 49% of urban houses have access to municipal services in this regard whereas 5% have hired people to do this task. The waster produced by houses that do not have access to a proper disposal system, throw it out on open spaces like streets, vacant plots, etc. polluting the environment continuously. According to a study by Japan International Cooperation Agency (JICA), the amount of solid waste generated in urban Pakistan is more than 55,000 tons per day, and waste collection in cities currently averages only 50% of waste generation. Similarly, a presentation titled as “Waste-to-Energy Potential on Pakistan” given before “Expert Group Meeting on Sustainable Application of Waste-to-Energy in Asian Region,” held in Busan, Korea, mentions that 71,000 tons of solid waste is generated per day in Pakistan, mostly from major metropolitan areas. It also mentions that about 60-70% of solid waste generated in the cities is collected. The remaining waste does go in our drainage system further hampering its ability to work properly.

Environmental and socio-economic impacts of urban flooding on individuals as well as the society are profound, and these may lead to a huge urban crisis. Since urban residents make an important part of a country’s population owing to their civic and economic impact, urban flooding disrupts civic life, leading to social and economic losses. Cities are playing a critical role in our national economy as they share 78% of trade and commercial activities; the metropolitan city of Karachi singularly handles 95% of foreign trade and contributes 20% to the national GDP and 30% to the manufacturing sector. Lahore, the second biggest city of the country, contributes 13.2% to national economy while Faisalabad generates 25% of the national revenue. Water that stagnates after urban flooding causes the spread of garbage, human and industrial waste, and mud all around the city due to which seasonal diseases, e.g. malaria, dengue, cholera, diarrhoea, asthma, etc. break out, further burdening the health system of the country, and for that matter the national exchequer.

 

The writer can be contacted at: misteratif@yahoo.com