In the current state of rapid urbanization rate around the world, functioning of infrastructure is necessary to ensure the wellbeing of residences in the cities. Drainage system is one of such structures whose failure can put a whole city on hold. Municipal drainage system constitutes artificial network of open or closed ditches or pipes with the main purpose of conveying storm water from the city. In Nigeria, many cities suffer from poorly designed as well as poorly maintained drainage networks.
Poor drainage system contributes greatly to the most of the flash floods in our cities. With most extreme rainfall events as a result of climate change being expected to largely affect African continent, effective drainage system would play a significant role in mitigating flood disasters that may occur.
Planning and Management
For most cities in Nigeria, the issue traces back to the planning and maintenance of the drainage systems. A well planned city shall have an efficient drainage network system that ensures the effectiveness and performance of other infrastructures. Unfortunately, even where there is a proper city plan, sticking to it becomes a huge challenge. The main reasons for that being lack of coordination between development/planning authorities and other sectors as well as apathy of the general public towards proper city planning.
Considering Abuja as an example, there have been complaints of many buildings being developed without proper drainage provisions. In some cases, developments are approved at locations blocking sewage lines and waterways. In addition to rendering the sewage and drainage networks inefficient, such buildings are also susceptible to foundation failures that result to collapse.
Similarly, a 2011 study conducted by Akukwe Thecla, a lecturer at the University of Nigeria Nsukka, on the causes of flooding in Port Harcourt revealed that most part of the city do not have adequate drainage facilities. This is despite the fact that Rivers State Government proposed a robust Greater Port Harcourt Development Plan in 2008 that could have transformed the city.
Maintenance of structures is as important as putting them in place. It is even more important for drainage system because failure or blockage at a single point renders the whole network ineffective. The dreadful state of drainages in Nigerian cities makes it seem as if there is no agency in charge of managing them or that the agency is not discharging its responsibility.
The most unfortunate plight surrounding our drainage systems is blockage from indiscriminate dumping of solid waste. This can partly be blamed on the absence of proper waste collection system as well as our collective lack of good sanitary attitude. Most people throw away trash in open areas without any second thought of the consequences. Such refuse gets transported by wind into the drains and becomes a source of blockage with time thereby undermining smooth water flow.
Disposal of waste in the open area has become a culture such that people do not even take notice of trash bins where they are provided. Street vending, especially of sachet water, other drinks and foodstuff is a contributing factor to the problem. Providing trash cans to accommodate such would require the cans be placed all over our cities. The menace of plastic waste in drainages does not stop at drain blockage. It usually ends up at large water bodies causing serious pollution and putting aquatic lives in danger.
As if that is not enough, household waste is often disposed by the road side in most neighborhoods. Instead of waste collection trucks taking garbage from houses, it is a common practice in most Nigerian cities for people to dispose it at certain locations while the trucks haul it to the landfill after it accumulates over a period of time. Unfortunately, some of these temporary disposal spots end up becoming permanent landfills.
A study carried out in 2013 by A. W. Butu and B. R. Ageda (Nigerian Defence Academy Kaduna) and A. A. Bichi (Federal College of Euducation Kano) in 2013 discovered several heaps of municipal waste across Abuja environs. Most of the refuse dumps were found to cause blockage to the drainages making them incapable of conveying runoff. When stagnation occurs, a dump can become a source of air pollution discharging heavy smell. Some of the materials contained in the solid waste are toxic with harmful chemicals that may pollute surface and groundwater in the area.
In addition to flood and pollution, poor drainage system is also responsible for road failures in many cases. The biggest enemy of tarred roads, which are commonly used in Nigeria, is water that does not quickly drain away. Poor drainage leads to road failure long before it reaches its design life.
The problems surrounding the drainage systems in Nigerian cities are evidently not the fault of few but we all play a role. It is therefore necessary for us to collectively work toward maintaining the valuable infrastructure. My next post will discuss what is required of a sustainable city with respect to drainage system.
Written by Sada.
Sada Haruna is the IT strategist at Green Habitat and a contributor to the blog. He is a PhD student in the department of Environmental Engineering at the University of Ottawa. His current research focuses on safe disposal of toxic mine wastes and remains an ardent advocate of environmental sustainability. He enjoys reading and coding at his leisure time. Follow him on Twitter @H_Sadah